From fe95cd2f4b3a722e023dc7bba8ff65136be441ca Mon Sep 17 00:00:00 2001
From: Mazdak Farrokhzad <twingoow@gmail.com>
Date: Wed, 30 Oct 2019 16:38:16 +0100
Subject: revamp pre-expansion gating infra

---
 src/libsyntax/parse/parser/item.rs | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

(limited to 'src/libsyntax/parse/parser/item.rs')

diff --git a/src/libsyntax/parse/parser/item.rs b/src/libsyntax/parse/parser/item.rs
index 5b60e7e6dba..51e96b55c72 100644
--- a/src/libsyntax/parse/parser/item.rs
+++ b/src/libsyntax/parse/parser/item.rs
@@ -147,9 +147,7 @@ impl<'a> Parser<'a> {
                 let unsafety = self.parse_unsafety();
 
                 if self.check_keyword(kw::Extern) {
-                    self.sess.gated_spans.const_extern_fn.borrow_mut().push(
-                        lo.to(self.token.span)
-                    );
+                    self.sess.gated_spans.gate(sym::const_extern_fn, lo.to(self.token.span));
                 }
                 let abi = self.parse_extern_abi()?;
                 self.bump(); // `fn`
@@ -830,7 +828,7 @@ impl<'a> Parser<'a> {
                     .emit();
             }
 
-            self.sess.gated_spans.trait_alias.borrow_mut().push(whole_span);
+            self.sess.gated_spans.gate(sym::trait_alias, whole_span);
 
             Ok((ident, ItemKind::TraitAlias(tps, bounds), None))
         } else {
@@ -1712,7 +1710,7 @@ impl<'a> Parser<'a> {
         let span = lo.to(self.prev_span);
 
         if !def.legacy {
-            self.sess.gated_spans.decl_macro.borrow_mut().push(span);
+            self.sess.gated_spans.gate(sym::decl_macro, span);
         }
 
         Ok(Some(self.mk_item(span, ident, ItemKind::MacroDef(def), vis.clone(), attrs.to_vec())))
-- 
cgit 1.4.1-3-g733a5


From eea6f23a0ed67fd8c6b8e1b02cda3628fee56b2f Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <nnethercote@mozilla.com>
Date: Thu, 24 Oct 2019 06:33:12 +1100
Subject: Make doc comments cheaper with `AttrKind`.

`AttrKind` is a new type with two variants, `Normal` and `DocComment`. It's a
big performance win (over 10% in some cases) because `DocComment` lets doc
comments (which are common) be represented very cheaply.

`Attribute` gets some new helper methods to ease the transition:
- `has_name()`: check if the attribute name matches a single `Symbol`; for
  `DocComment` variants it succeeds if the symbol is `sym::doc`.
- `is_doc_comment()`: check if it has a `DocComment` kind.
- `{get,unwrap}_normal_item()`: extract the item from a `Normal` variant;
  panic otherwise.

Fixes #60935.
---
 src/librustc/hir/lowering.rs                |  16 ++--
 src/librustc/ich/impls_syntax.rs            |  25 +++----
 src/librustc_lint/builtin.rs                |   6 +-
 src/librustc_metadata/link_args.rs          |   2 +-
 src/librustc_passes/ast_validation.rs       |   2 +-
 src/librustc_resolve/build_reduced_graph.rs |   6 +-
 src/librustc_resolve/macros.rs              |   2 +-
 src/librustc_save_analysis/lib.rs           |   4 +-
 src/librustc_typeck/collect.rs              |   4 +-
 src/librustdoc/clean/mod.rs                 |  47 ++++++------
 src/libsyntax/ast.rs                        |  19 ++++-
 src/libsyntax/attr/builtin.rs               |   8 +-
 src/libsyntax/attr/mod.rs                   | 110 ++++++++++++++++++++--------
 src/libsyntax/config.rs                     |   9 +--
 src/libsyntax/feature_gate/check.rs         |   3 +-
 src/libsyntax/mut_visit.rs                  |  12 ++-
 src/libsyntax/parse/mod.rs                  |  22 +++---
 src/libsyntax/parse/parser/attr.rs          |   7 +-
 src/libsyntax/parse/parser/item.rs          |  12 +--
 src/libsyntax/parse/tests.rs                |   2 +-
 src/libsyntax/print/pprust.rs               |  21 +++---
 src/libsyntax/visit.rs                      |   5 +-
 src/libsyntax_expand/expand.rs              |  18 +++--
 src/libsyntax_expand/proc_macro.rs          |   4 +-
 src/libsyntax_ext/proc_macro_harness.rs     |  14 ++--
 25 files changed, 233 insertions(+), 147 deletions(-)

(limited to 'src/libsyntax/parse/parser/item.rs')

diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index 067fefd3210..230fbb16b87 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -997,14 +997,20 @@ impl<'a> LoweringContext<'a> {
         // Note that we explicitly do not walk the path. Since we don't really
         // lower attributes (we use the AST version) there is nowhere to keep
         // the `HirId`s. We don't actually need HIR version of attributes anyway.
+        let kind = match attr.kind {
+            AttrKind::Normal(ref item) => {
+                AttrKind::Normal(AttrItem {
+                    path: item.path.clone(),
+                    tokens: self.lower_token_stream(item.tokens.clone()),
+                })
+            }
+            AttrKind::DocComment(comment) => AttrKind::DocComment(comment)
+        };
+
         Attribute {
-            item: AttrItem {
-                path: attr.item.path.clone(),
-                tokens: self.lower_token_stream(attr.item.tokens.clone()),
-            },
+            kind,
             id: attr.id,
             style: attr.style,
-            is_sugared_doc: attr.is_sugared_doc,
             span: attr.span,
         }
     }
diff --git a/src/librustc/ich/impls_syntax.rs b/src/librustc/ich/impls_syntax.rs
index 304735fb1c7..aa147462e3d 100644
--- a/src/librustc/ich/impls_syntax.rs
+++ b/src/librustc/ich/impls_syntax.rs
@@ -177,7 +177,7 @@ impl<'a> HashStable<StableHashingContext<'a>> for [ast::Attribute] {
         let filtered: SmallVec<[&ast::Attribute; 8]> = self
             .iter()
             .filter(|attr| {
-                !attr.is_sugared_doc &&
+                !attr.is_doc_comment() &&
                 !attr.ident().map_or(false, |ident| hcx.is_ignored_attr(ident.name))
             })
             .collect();
@@ -207,19 +207,16 @@ impl<'a> HashStable<StableHashingContext<'a>> for ast::Attribute {
     fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
         // Make sure that these have been filtered out.
         debug_assert!(!self.ident().map_or(false, |ident| hcx.is_ignored_attr(ident.name)));
-        debug_assert!(!self.is_sugared_doc);
-
-        let ast::Attribute {
-            ref item,
-            id: _,
-            style,
-            is_sugared_doc: _,
-            span,
-        } = *self;
-
-        item.hash_stable(hcx, hasher);
-        style.hash_stable(hcx, hasher);
-        span.hash_stable(hcx, hasher);
+        debug_assert!(!self.is_doc_comment());
+
+        let ast::Attribute { kind, id: _, style, span } = self;
+        if let ast::AttrKind::Normal(item) = kind {
+            item.hash_stable(hcx, hasher);
+            style.hash_stable(hcx, hasher);
+            span.hash_stable(hcx, hasher);
+        } else {
+            unreachable!();
+        }
     }
 }
 
diff --git a/src/librustc_lint/builtin.rs b/src/librustc_lint/builtin.rs
index 5bc8a0e16a2..d40af615eb1 100644
--- a/src/librustc_lint/builtin.rs
+++ b/src/librustc_lint/builtin.rs
@@ -706,7 +706,7 @@ impl EarlyLintPass for DeprecatedAttr {
             }
         }
         if attr.check_name(sym::no_start) || attr.check_name(sym::crate_id) {
-            let path_str = pprust::path_to_string(&attr.item.path);
+            let path_str = pprust::path_to_string(&attr.get_normal_item().path);
             let msg = format!("use of deprecated attribute `{}`: no longer used.", path_str);
             lint_deprecated_attr(cx, attr, &msg, None);
         }
@@ -736,7 +736,7 @@ impl UnusedDocComment {
         let mut sugared_span: Option<Span> = None;
 
         while let Some(attr) = attrs.next() {
-            if attr.is_sugared_doc {
+            if attr.is_doc_comment() {
                 sugared_span = Some(
                     sugared_span.map_or_else(
                         || attr.span,
@@ -745,7 +745,7 @@ impl UnusedDocComment {
                 );
             }
 
-            if attrs.peek().map(|next_attr| next_attr.is_sugared_doc).unwrap_or_default() {
+            if attrs.peek().map(|next_attr| next_attr.is_doc_comment()).unwrap_or_default() {
                 continue;
             }
 
diff --git a/src/librustc_metadata/link_args.rs b/src/librustc_metadata/link_args.rs
index 1b10cff5689..b40d58a6819 100644
--- a/src/librustc_metadata/link_args.rs
+++ b/src/librustc_metadata/link_args.rs
@@ -11,7 +11,7 @@ crate fn collect(tcx: TyCtxt<'_>) -> Vec<String> {
     tcx.hir().krate().visit_all_item_likes(&mut collector);
 
     for attr in tcx.hir().krate().attrs.iter() {
-        if attr.item.path == sym::link_args {
+        if attr.has_name(sym::link_args) {
             if let Some(linkarg) = attr.value_str() {
                 collector.add_link_args(&linkarg.as_str());
             }
diff --git a/src/librustc_passes/ast_validation.rs b/src/librustc_passes/ast_validation.rs
index e625334040e..d1a801b3006 100644
--- a/src/librustc_passes/ast_validation.rs
+++ b/src/librustc_passes/ast_validation.rs
@@ -328,7 +328,7 @@ impl<'a> AstValidator<'a> {
                 let arr = [sym::allow, sym::cfg, sym::cfg_attr, sym::deny, sym::forbid, sym::warn];
                 !arr.contains(&attr.name_or_empty()) && is_builtin_attr(attr)
             })
-            .for_each(|attr| if attr.is_sugared_doc {
+            .for_each(|attr| if attr.is_doc_comment() {
                 let mut err = self.err_handler().struct_span_err(
                     attr.span,
                     "documentation comments cannot be applied to function parameters"
diff --git a/src/librustc_resolve/build_reduced_graph.rs b/src/librustc_resolve/build_reduced_graph.rs
index 4849ec25560..55f054d0be3 100644
--- a/src/librustc_resolve/build_reduced_graph.rs
+++ b/src/librustc_resolve/build_reduced_graph.rs
@@ -1229,8 +1229,10 @@ impl<'a, 'b> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b> {
     }
 
     fn visit_attribute(&mut self, attr: &'b ast::Attribute) {
-        if !attr.is_sugared_doc && is_builtin_attr(attr) {
-            self.r.builtin_attrs.push((attr.item.path.segments[0].ident, self.parent_scope));
+        if !attr.is_doc_comment() && is_builtin_attr(attr) {
+            self.r.builtin_attrs.push(
+                (attr.get_normal_item().path.segments[0].ident, self.parent_scope)
+            );
         }
         visit::walk_attribute(self, attr);
     }
diff --git a/src/librustc_resolve/macros.rs b/src/librustc_resolve/macros.rs
index f4338d24629..3d5a7f26eda 100644
--- a/src/librustc_resolve/macros.rs
+++ b/src/librustc_resolve/macros.rs
@@ -179,7 +179,7 @@ impl<'a> base::Resolver for Resolver<'a> {
 
         let (path, kind, derives, after_derive) = match invoc.kind {
             InvocationKind::Attr { ref attr, ref derives, after_derive, .. } =>
-                (&attr.item.path,
+                (&attr.get_normal_item().path,
                  MacroKind::Attr,
                  self.arenas.alloc_ast_paths(derives),
                  after_derive),
diff --git a/src/librustc_save_analysis/lib.rs b/src/librustc_save_analysis/lib.rs
index 7592df57fc6..9408bbe557a 100644
--- a/src/librustc_save_analysis/lib.rs
+++ b/src/librustc_save_analysis/lib.rs
@@ -885,7 +885,7 @@ impl<'l, 'tcx> SaveContext<'l, 'tcx> {
         for attr in attrs {
             if attr.check_name(sym::doc) {
                 if let Some(val) = attr.value_str() {
-                    if attr.is_sugared_doc {
+                    if attr.is_doc_comment() {
                         result.push_str(&strip_doc_comment_decoration(&val.as_str()));
                     } else {
                         result.push_str(&val.as_str());
@@ -1195,7 +1195,7 @@ fn null_id() -> rls_data::Id {
 fn lower_attributes(attrs: Vec<Attribute>, scx: &SaveContext<'_, '_>) -> Vec<rls_data::Attribute> {
     attrs.into_iter()
     // Only retain real attributes. Doc comments are lowered separately.
-    .filter(|attr| attr.item.path != sym::doc)
+    .filter(|attr| !attr.has_name(sym::doc))
     .map(|mut attr| {
         // Remove the surrounding '#[..]' or '#![..]' of the pretty printed
         // attribute. First normalize all inner attribute (#![..]) to outer
diff --git a/src/librustc_typeck/collect.rs b/src/librustc_typeck/collect.rs
index 09e372ac830..71a7b52a27b 100644
--- a/src/librustc_typeck/collect.rs
+++ b/src/librustc_typeck/collect.rs
@@ -2706,7 +2706,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
     }
 
     codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
-        if attr.item.path != sym::inline {
+        if !attr.has_name(sym::inline) {
             return ia;
         }
         match attr.meta().map(|i| i.kind) {
@@ -2746,7 +2746,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
     });
 
     codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
-        if attr.item.path != sym::optimize {
+        if !attr.has_name(sym::optimize) {
             return ia;
         }
         let err = |sp, s| span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s);
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index e7f76155252..32c8ca234a0 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -26,7 +26,7 @@ use rustc::ty::{self, DefIdTree, TyCtxt, Region, RegionVid, Ty, AdtKind};
 use rustc::ty::fold::TypeFolder;
 use rustc::ty::layout::VariantIdx;
 use rustc::util::nodemap::{FxHashMap, FxHashSet};
-use syntax::ast::{self, Attribute, AttrStyle, AttrItem, Ident};
+use syntax::ast::{self, Attribute, AttrStyle, AttrKind, Ident};
 use syntax::attr;
 use syntax::parse::lexer::comments;
 use syntax::source_map::DUMMY_SP;
@@ -859,31 +859,32 @@ impl Attributes {
         let mut cfg = Cfg::True;
         let mut doc_line = 0;
 
-        /// Converts `attr` to a normal `#[doc="foo"]` comment, if it is a
-        /// comment like `///` or `/** */`. (Returns `attr` unchanged for
-        /// non-sugared doc attributes.)
-        pub fn with_desugared_doc<T>(attr: &Attribute, f: impl FnOnce(&Attribute) -> T) -> T {
-            if attr.is_sugared_doc {
-                let comment = attr.value_str().unwrap();
-                let meta = attr::mk_name_value_item_str(
-                    Ident::with_dummy_span(sym::doc),
-                    Symbol::intern(&comments::strip_doc_comment_decoration(&comment.as_str())),
-                    DUMMY_SP,
-                );
-                f(&Attribute {
-                    item: AttrItem { path: meta.path, tokens: meta.kind.tokens(meta.span) },
-                    id: attr.id,
-                    style: attr.style,
-                    is_sugared_doc: true,
-                    span: attr.span,
-                })
-            } else {
-                f(attr)
+        /// If `attr` is a doc comment, strips the leading and (if present)
+        /// trailing comments symbols, e.g. `///`, `/**`, and `*/`. Otherwise,
+        /// returns `attr` unchanged.
+        pub fn with_doc_comment_markers_stripped<T>(
+            attr: &Attribute,
+            f: impl FnOnce(&Attribute) -> T
+        ) -> T {
+            match attr.kind {
+                AttrKind::Normal(_) => {
+                    f(attr)
+                }
+                AttrKind::DocComment(comment) => {
+                    let comment =
+                        Symbol::intern(&comments::strip_doc_comment_decoration(&comment.as_str()));
+                    f(&Attribute {
+                        kind: AttrKind::DocComment(comment),
+                        id: attr.id,
+                        style: attr.style,
+                        span: attr.span,
+                    })
+                }
             }
         }
 
         let other_attrs = attrs.iter().filter_map(|attr| {
-            with_desugared_doc(attr, |attr| {
+            with_doc_comment_markers_stripped(attr, |attr| {
                 if attr.check_name(sym::doc) {
                     if let Some(mi) = attr.meta() {
                         if let Some(value) = mi.value_str() {
@@ -892,7 +893,7 @@ impl Attributes {
                             let line = doc_line;
                             doc_line += value.lines().count();
 
-                            if attr.is_sugared_doc {
+                            if attr.is_doc_comment() {
                                 doc_strings.push(DocFragment::SugaredDoc(line, attr.span, value));
                             } else {
                                 doc_strings.push(DocFragment::RawDoc(line, attr.span, value));
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index df1fb5d97d7..2392b809150 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -2190,18 +2190,31 @@ pub struct AttrItem {
 }
 
 /// Metadata associated with an item.
-/// Doc-comments are promoted to attributes that have `is_sugared_doc = true`.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Attribute {
-    pub item: AttrItem,
+    pub kind: AttrKind,
     pub id: AttrId,
     /// Denotes if the attribute decorates the following construct (outer)
     /// or the construct this attribute is contained within (inner).
     pub style: AttrStyle,
-    pub is_sugared_doc: bool,
     pub span: Span,
 }
 
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
+pub enum AttrKind {
+    /// A normal attribute.
+    Normal(AttrItem),
+
+    /// A doc comment (e.g. `/// ...`, `//! ...`, `/** ... */`, `/*! ... */`).
+    /// Doc attributes (e.g. `#[doc="..."]`) are represented with the `Normal`
+    /// variant (which is much less compact and thus more expensive).
+    ///
+    /// Note: `self.has_name(sym::doc)` and `self.check_name(sym::doc)` succeed
+    /// for this variant, but this may change in the future.
+    /// ```
+    DocComment(Symbol),
+}
+
 /// `TraitRef`s appear in impls.
 ///
 /// Resolution maps each `TraitRef`'s `ref_id` to its defining trait; that's all
diff --git a/src/libsyntax/attr/builtin.rs b/src/libsyntax/attr/builtin.rs
index e77d9ef326a..787d69f5e99 100644
--- a/src/libsyntax/attr/builtin.rs
+++ b/src/libsyntax/attr/builtin.rs
@@ -228,7 +228,7 @@ fn find_stability_generic<'a, I>(sess: &ParseSess,
             sym::stable,
             sym::rustc_promotable,
             sym::rustc_allow_const_fn_ptr,
-        ].iter().any(|&s| attr.item.path == s) {
+        ].iter().any(|&s| attr.has_name(s)) {
             continue // not a stability level
         }
 
@@ -236,10 +236,10 @@ fn find_stability_generic<'a, I>(sess: &ParseSess,
 
         let meta = attr.meta();
 
-        if attr.item.path == sym::rustc_promotable {
+        if attr.has_name(sym::rustc_promotable) {
             promotable = true;
         }
-        if attr.item.path == sym::rustc_allow_const_fn_ptr {
+        if attr.has_name(sym::rustc_allow_const_fn_ptr) {
             allow_const_fn_ptr = true;
         }
         // attributes with data
@@ -778,7 +778,7 @@ pub fn find_repr_attrs(sess: &ParseSess, attr: &Attribute) -> Vec<ReprAttr> {
 
     let mut acc = Vec::new();
     let diagnostic = &sess.span_diagnostic;
-    if attr.item.path == sym::repr {
+    if attr.has_name(sym::repr) {
         if let Some(items) = attr.meta_item_list() {
             mark_used(attr);
             for item in items {
diff --git a/src/libsyntax/attr/mod.rs b/src/libsyntax/attr/mod.rs
index 0c46c501be9..c663995eb8f 100644
--- a/src/libsyntax/attr/mod.rs
+++ b/src/libsyntax/attr/mod.rs
@@ -9,7 +9,7 @@ pub use StabilityLevel::*;
 pub use crate::ast::Attribute;
 
 use crate::ast;
-use crate::ast::{AttrItem, AttrId, AttrStyle, Name, Ident, Path, PathSegment};
+use crate::ast::{AttrItem, AttrId, AttrKind, AttrStyle, Name, Ident, Path, PathSegment};
 use crate::ast::{MetaItem, MetaItemKind, NestedMetaItem};
 use crate::ast::{Lit, LitKind, Expr, Item, Local, Stmt, StmtKind, GenericParam};
 use crate::mut_visit::visit_clobber;
@@ -145,12 +145,17 @@ impl NestedMetaItem {
 }
 
 impl Attribute {
+    pub fn has_name(&self, name: Symbol) -> bool {
+        match self.kind {
+            AttrKind::Normal(ref item) => item.path == name,
+            AttrKind::DocComment(_) => name == sym::doc,
+        }
+    }
+
     /// Returns `true` if the attribute's path matches the argument. If it matches, then the
     /// attribute is marked as used.
-    ///
-    /// To check the attribute name without marking it used, use the `path` field directly.
     pub fn check_name(&self, name: Symbol) -> bool {
-        let matches = self.item.path == name;
+        let matches = self.has_name(name);
         if matches {
             mark_used(self);
         }
@@ -159,10 +164,15 @@ impl Attribute {
 
     /// For a single-segment attribute, returns its name; otherwise, returns `None`.
     pub fn ident(&self) -> Option<Ident> {
-        if self.item.path.segments.len() == 1 {
-            Some(self.item.path.segments[0].ident)
-        } else {
-            None
+        match self.kind {
+            AttrKind::Normal(ref item) => {
+                if item.path.segments.len() == 1 {
+                    Some(item.path.segments[0].ident)
+                } else {
+                    None
+                }
+            }
+            AttrKind::DocComment(_) => Some(Ident::new(sym::doc, self.span)),
         }
     }
     pub fn name_or_empty(&self) -> Symbol {
@@ -170,18 +180,32 @@ impl Attribute {
     }
 
     pub fn value_str(&self) -> Option<Symbol> {
-        self.meta().and_then(|meta| meta.value_str())
+        match self.kind {
+            AttrKind::Normal(ref item) => {
+                item.meta(self.span).and_then(|meta| meta.value_str())
+            }
+            AttrKind::DocComment(comment) => Some(comment),
+        }
     }
 
     pub fn meta_item_list(&self) -> Option<Vec<NestedMetaItem>> {
-        match self.meta() {
-            Some(MetaItem { kind: MetaItemKind::List(list), .. }) => Some(list),
-            _ => None
+        match self.kind {
+            AttrKind::Normal(ref item) => {
+                match item.meta(self.span) {
+                    Some(MetaItem { kind: MetaItemKind::List(list), .. }) => Some(list),
+                    _ => None
+                }
+            }
+            AttrKind::DocComment(_) => None,
         }
     }
 
     pub fn is_word(&self) -> bool {
-        self.item.tokens.is_empty()
+        if let AttrKind::Normal(item) = &self.kind {
+            item.tokens.is_empty()
+        } else {
+            false
+        }
     }
 
     pub fn is_meta_item_list(&self) -> bool {
@@ -275,17 +299,49 @@ impl AttrItem {
 }
 
 impl Attribute {
+    pub fn is_doc_comment(&self) -> bool {
+        match self.kind {
+            AttrKind::Normal(_) => false,
+            AttrKind::DocComment(_) => true,
+        }
+    }
+
+    pub fn get_normal_item(&self) -> &AttrItem {
+        match self.kind {
+            AttrKind::Normal(ref item) => item,
+            AttrKind::DocComment(_) => panic!("unexpected sugared doc"),
+        }
+    }
+
+    pub fn unwrap_normal_item(self) -> AttrItem {
+        match self.kind {
+            AttrKind::Normal(item) => item,
+            AttrKind::DocComment(_) => panic!("unexpected sugared doc"),
+        }
+    }
+
     /// Extracts the MetaItem from inside this Attribute.
     pub fn meta(&self) -> Option<MetaItem> {
-        self.item.meta(self.span)
+        match self.kind {
+            AttrKind::Normal(ref item) => item.meta(self.span),
+            AttrKind::DocComment(comment) =>
+                Some(mk_name_value_item_str(Ident::new(sym::doc, self.span), comment, self.span)),
+        }
     }
 
     pub fn parse_meta<'a>(&self, sess: &'a ParseSess) -> PResult<'a, MetaItem> {
-        Ok(MetaItem {
-            path: self.item.path.clone(),
-            kind: parse::parse_in_attr(sess, self, |p| p.parse_meta_item_kind())?,
-            span: self.span,
-        })
+        match self.kind {
+            AttrKind::Normal(ref item) => {
+                Ok(MetaItem {
+                    path: item.path.clone(),
+                    kind: parse::parse_in_attr(sess, self, |parser| parser.parse_meta_item_kind())?,
+                    span: self.span,
+                })
+            }
+            AttrKind::DocComment(comment) => {
+                Ok(mk_name_value_item_str(Ident::new(sym::doc, self.span), comment, self.span))
+            }
+        }
     }
 }
 
@@ -327,10 +383,9 @@ crate fn mk_attr_id() -> AttrId {
 
 pub fn mk_attr(style: AttrStyle, path: Path, tokens: TokenStream, span: Span) -> Attribute {
     Attribute {
-        item: AttrItem { path, tokens },
+        kind: AttrKind::Normal(AttrItem { path, tokens }),
         id: mk_attr_id(),
         style,
-        is_sugared_doc: false,
         span,
     }
 }
@@ -345,18 +400,11 @@ pub fn mk_attr_outer(item: MetaItem) -> Attribute {
     mk_attr(AttrStyle::Outer, item.path, item.kind.tokens(item.span), item.span)
 }
 
-pub fn mk_sugared_doc_attr(text: Symbol, span: Span) -> Attribute {
-    let style = doc_comment_style(&text.as_str());
-    let lit_kind = LitKind::Str(text, ast::StrStyle::Cooked);
-    let lit = Lit::from_lit_kind(lit_kind, span);
+pub fn mk_doc_comment(comment: Symbol, span: Span) -> Attribute {
     Attribute {
-        item: AttrItem {
-            path: Path::from_ident(Ident::with_dummy_span(sym::doc).with_span_pos(span)),
-            tokens: MetaItemKind::NameValue(lit).tokens(span),
-        },
+        kind: AttrKind::DocComment(comment),
         id: mk_attr_id(),
-        style,
-        is_sugared_doc: true,
+        style: doc_comment_style(&comment.as_str()),
         span,
     }
 }
diff --git a/src/libsyntax/config.rs b/src/libsyntax/config.rs
index 682c8f71dc8..5f89ed36e2a 100644
--- a/src/libsyntax/config.rs
+++ b/src/libsyntax/config.rs
@@ -93,10 +93,10 @@ impl<'a> StripUnconfigured<'a> {
     /// is in the original source file. Gives a compiler error if the syntax of
     /// the attribute is incorrect.
     fn process_cfg_attr(&mut self, attr: ast::Attribute) -> Vec<ast::Attribute> {
-        if attr.item.path != sym::cfg_attr {
+        if !attr.has_name(sym::cfg_attr) {
             return vec![attr];
         }
-        if attr.item.tokens.is_empty() {
+        if attr.get_normal_item().tokens.is_empty() {
             self.sess.span_diagnostic
                 .struct_span_err(
                     attr.span,
@@ -136,10 +136,9 @@ impl<'a> StripUnconfigured<'a> {
             //  `#[cfg_attr(false, cfg_attr(true, some_attr))]`.
             expanded_attrs.into_iter()
             .flat_map(|(item, span)| self.process_cfg_attr(ast::Attribute {
-                item,
+                kind: ast::AttrKind::Normal(item),
                 id: attr::mk_attr_id(),
                 style: attr.style,
-                is_sugared_doc: false,
                 span,
             }))
             .collect()
@@ -212,7 +211,7 @@ impl<'a> StripUnconfigured<'a> {
                                       GateIssue::Language,
                                       EXPLAIN_STMT_ATTR_SYNTAX);
 
-            if attr.is_sugared_doc {
+            if attr.is_doc_comment() {
                 err.help("`///` is for documentation comments. For a plain comment, use `//`.");
             }
 
diff --git a/src/libsyntax/feature_gate/check.rs b/src/libsyntax/feature_gate/check.rs
index c19ed774507..b7e75ff3a7e 100644
--- a/src/libsyntax/feature_gate/check.rs
+++ b/src/libsyntax/feature_gate/check.rs
@@ -329,7 +329,8 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             // `rustc_dummy` doesn't have any restrictions specific to built-in attributes.
             Some((name, _, template, _)) if name != sym::rustc_dummy =>
                 check_builtin_attribute(self.parse_sess, attr, name, template),
-            _ => if let Some(TokenTree::Token(token)) = attr.item.tokens.trees().next() {
+            _ => if let Some(TokenTree::Token(token)) =
+                    attr.get_normal_item().tokens.trees().next() {
                 if token == token::Eq {
                     // All key-value attributes are restricted to meta-item syntax.
                     attr.parse_meta(self.parse_sess).map_err(|mut err| err.emit()).ok();
diff --git a/src/libsyntax/mut_visit.rs b/src/libsyntax/mut_visit.rs
index 60ee17d09b7..7261601e144 100644
--- a/src/libsyntax/mut_visit.rs
+++ b/src/libsyntax/mut_visit.rs
@@ -550,10 +550,14 @@ pub fn noop_visit_local<T: MutVisitor>(local: &mut P<Local>, vis: &mut T) {
 }
 
 pub fn noop_visit_attribute<T: MutVisitor>(attr: &mut Attribute, vis: &mut T) {
-    let Attribute { item: AttrItem { path, tokens }, id: _, style: _, is_sugared_doc: _, span }
-        = attr;
-    vis.visit_path(path);
-    vis.visit_tts(tokens);
+    let Attribute { kind, id: _, style: _, span } = attr;
+    match kind {
+        AttrKind::Normal(AttrItem { path, tokens }) => {
+            vis.visit_path(path);
+            vis.visit_tts(tokens);
+        }
+        AttrKind::DocComment(_) => {}
+    }
     vis.visit_span(span);
 }
 
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index 6cfa0dfad82..b688dce87c1 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -287,7 +287,7 @@ pub fn parse_in_attr<'a, T>(
 ) -> PResult<'a, T> {
     let mut parser = Parser::new(
         sess,
-        attr.item.tokens.clone(),
+        attr.get_normal_item().tokens.clone(),
         None,
         false,
         false,
@@ -393,18 +393,22 @@ fn prepend_attrs(
 
         let source = pprust::attribute_to_string(attr);
         let macro_filename = FileName::macro_expansion_source_code(&source);
-        if attr.is_sugared_doc {
-            let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span));
-            builder.push(stream);
-            continue
-        }
+
+        let item = match attr.kind {
+            ast::AttrKind::Normal(ref item) => item,
+            ast::AttrKind::DocComment(_) => {
+                let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span));
+                builder.push(stream);
+                continue
+            }
+        };
 
         // synthesize # [ $path $tokens ] manually here
         let mut brackets = tokenstream::TokenStreamBuilder::new();
 
         // For simple paths, push the identifier directly
-        if attr.item.path.segments.len() == 1 && attr.item.path.segments[0].args.is_none() {
-            let ident = attr.item.path.segments[0].ident;
+        if item.path.segments.len() == 1 && item.path.segments[0].args.is_none() {
+            let ident = item.path.segments[0].ident;
             let token = token::Ident(ident.name, ident.as_str().starts_with("r#"));
             brackets.push(tokenstream::TokenTree::token(token, ident.span));
 
@@ -415,7 +419,7 @@ fn prepend_attrs(
             brackets.push(stream);
         }
 
-        brackets.push(attr.item.tokens.clone());
+        brackets.push(item.tokens.clone());
 
         // The span we list here for `#` and for `[ ... ]` are both wrong in
         // that it encompasses more than each token, but it hopefully is "good
diff --git a/src/libsyntax/parse/parser/attr.rs b/src/libsyntax/parse/parser/attr.rs
index 188a144cac9..1c292661f24 100644
--- a/src/libsyntax/parse/parser/attr.rs
+++ b/src/libsyntax/parse/parser/attr.rs
@@ -43,7 +43,7 @@ impl<'a> Parser<'a> {
                     just_parsed_doc_comment = false;
                 }
                 token::DocComment(s) => {
-                    let attr = attr::mk_sugared_doc_attr(s, self.token.span);
+                    let attr = attr::mk_doc_comment(s, self.token.span);
                     if attr.style != ast::AttrStyle::Outer {
                         let mut err = self.fatal("expected outer doc comment");
                         err.note("inner doc comments like this (starting with \
@@ -150,10 +150,9 @@ impl<'a> Parser<'a> {
         };
 
         Ok(ast::Attribute {
-            item,
+            kind: ast::AttrKind::Normal(item),
             id: attr::mk_attr_id(),
             style,
-            is_sugared_doc: false,
             span,
         })
     }
@@ -229,7 +228,7 @@ impl<'a> Parser<'a> {
                 }
                 token::DocComment(s) => {
                     // We need to get the position of this token before we bump.
-                    let attr = attr::mk_sugared_doc_attr(s, self.token.span);
+                    let attr = attr::mk_doc_comment(s, self.token.span);
                     if attr.style == ast::AttrStyle::Inner {
                         attrs.push(attr);
                         self.bump();
diff --git a/src/libsyntax/parse/parser/item.rs b/src/libsyntax/parse/parser/item.rs
index 5b60e7e6dba..cc6235c6fc7 100644
--- a/src/libsyntax/parse/parser/item.rs
+++ b/src/libsyntax/parse/parser/item.rs
@@ -3,8 +3,8 @@ use super::diagnostics::{Error, dummy_arg, ConsumeClosingDelim};
 
 use crate::maybe_whole;
 use crate::ptr::P;
-use crate::ast::{self, DUMMY_NODE_ID, Ident, Attribute, AttrStyle, AnonConst, Item, ItemKind};
-use crate::ast::{ImplItem, ImplItemKind, TraitItem, TraitItemKind, UseTree, UseTreeKind};
+use crate::ast::{self, DUMMY_NODE_ID, Ident, Attribute, AttrKind, AttrStyle, AnonConst, Item};
+use crate::ast::{ItemKind, ImplItem, ImplItemKind, TraitItem, TraitItemKind, UseTree, UseTreeKind};
 use crate::ast::{PathSegment, IsAuto, Constness, IsAsync, Unsafety, Defaultness};
 use crate::ast::{Visibility, VisibilityKind, Mutability, FnHeader, ForeignItem, ForeignItemKind};
 use crate::ast::{Ty, TyKind, Generics, GenericBounds, TraitRef, EnumDef, VariantData, StructField};
@@ -483,12 +483,14 @@ impl<'a> Parser<'a> {
     /// Emits an expected-item-after-attributes error.
     fn expected_item_err(&mut self, attrs: &[Attribute]) -> PResult<'a,  ()> {
         let message = match attrs.last() {
-            Some(&Attribute { is_sugared_doc: true, .. }) => "expected item after doc comment",
-            _ => "expected item after attributes",
+            Some(&Attribute { kind: AttrKind::DocComment(_), .. }) =>
+                "expected item after doc comment",
+            _ =>
+                "expected item after attributes",
         };
 
         let mut err = self.diagnostic().struct_span_err(self.prev_span, message);
-        if attrs.last().unwrap().is_sugared_doc {
+        if attrs.last().unwrap().is_doc_comment() {
             err.span_label(self.prev_span, "this doc comment doesn't document anything");
         }
         Err(err)
diff --git a/src/libsyntax/parse/tests.rs b/src/libsyntax/parse/tests.rs
index 3bdb9227b4e..169eb954efa 100644
--- a/src/libsyntax/parse/tests.rs
+++ b/src/libsyntax/parse/tests.rs
@@ -246,7 +246,7 @@ let mut fflags: c_int = wb();
         let source = "/// doc comment\r\n/// line 2\r\nfn foo() {}".to_string();
         let item = parse_item_from_source_str(name_2, source, &sess)
             .unwrap().unwrap();
-        let docs = item.attrs.iter().filter(|a| a.path == sym::doc)
+        let docs = item.attrs.iter().filter(|a| a.has_name(sym::doc))
                     .map(|a| a.value_str().unwrap().to_string()).collect::<Vec<_>>();
         let b: &[_] = &["/// doc comment".to_string(), "/// line 2".to_string()];
         assert_eq!(&docs[..], b);
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 74ab5c79019..c8afe8a1ff4 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -622,16 +622,19 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
             self.hardbreak_if_not_bol();
         }
         self.maybe_print_comment(attr.span.lo());
-        if attr.is_sugared_doc {
-            self.word(attr.value_str().unwrap().to_string());
-            self.hardbreak()
-        } else {
-            match attr.style {
-                ast::AttrStyle::Inner => self.word("#!["),
-                ast::AttrStyle::Outer => self.word("#["),
+        match attr.kind {
+            ast::AttrKind::Normal(ref item) => {
+                match attr.style {
+                    ast::AttrStyle::Inner => self.word("#!["),
+                    ast::AttrStyle::Outer => self.word("#["),
+                }
+                self.print_attr_item(&item, attr.span);
+                self.word("]");
+            }
+            ast::AttrKind::DocComment(comment) => {
+                self.word(comment.to_string());
+                self.hardbreak()
             }
-            self.print_attr_item(&attr.item, attr.span);
-            self.word("]");
         }
     }
 
diff --git a/src/libsyntax/visit.rs b/src/libsyntax/visit.rs
index 64393a295de..117787d08c7 100644
--- a/src/libsyntax/visit.rs
+++ b/src/libsyntax/visit.rs
@@ -846,7 +846,10 @@ pub fn walk_vis<'a, V: Visitor<'a>>(visitor: &mut V, vis: &'a Visibility) {
 }
 
 pub fn walk_attribute<'a, V: Visitor<'a>>(visitor: &mut V, attr: &'a Attribute) {
-    visitor.visit_tts(attr.item.tokens.clone());
+    match attr.kind {
+        AttrKind::Normal(ref item) => visitor.visit_tts(item.tokens.clone()),
+        AttrKind::DocComment(_) => {}
+    }
 }
 
 pub fn walk_tt<'a, V: Visitor<'a>>(visitor: &mut V, tt: TokenTree) {
diff --git a/src/libsyntax_expand/expand.rs b/src/libsyntax_expand/expand.rs
index 392563587ba..7dbc7787010 100644
--- a/src/libsyntax_expand/expand.rs
+++ b/src/libsyntax_expand/expand.rs
@@ -419,7 +419,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                     }
 
                     let mut item = self.fully_configure(item);
-                    item.visit_attrs(|attrs| attrs.retain(|a| a.item.path != sym::derive));
+                    item.visit_attrs(|attrs| attrs.retain(|a| !a.has_name(sym::derive)));
                     let mut helper_attrs = Vec::new();
                     let mut has_copy = false;
                     for ext in exts {
@@ -634,9 +634,10 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                         | Annotatable::Variant(..)
                             => panic!("unexpected annotatable"),
                     })), DUMMY_SP).into();
-                    let input = self.extract_proc_macro_attr_input(attr.item.tokens, span);
+                    let item = attr.unwrap_normal_item();
+                    let input = self.extract_proc_macro_attr_input(item.tokens, span);
                     let tok_result = expander.expand(self.cx, span, input, item_tok);
-                    self.parse_ast_fragment(tok_result, fragment_kind, &attr.item.path, span)
+                    self.parse_ast_fragment(tok_result, fragment_kind, &item.path, span)
                 }
                 SyntaxExtensionKind::LegacyAttr(expander) => {
                     match attr.parse_meta(self.cx.parse_sess) {
@@ -974,7 +975,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                        -> Option<ast::Attribute> {
         let attr = attrs.iter()
                         .position(|a| {
-                            if a.item.path == sym::derive {
+                            if a.has_name(sym::derive) {
                                 *after_derive = true;
                             }
                             !attr::is_known(a) && !is_builtin_attr(a)
@@ -982,7 +983,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                         .map(|i| attrs.remove(i));
         if let Some(attr) = &attr {
             if !self.cx.ecfg.custom_inner_attributes() &&
-               attr.style == ast::AttrStyle::Inner && attr.item.path != sym::test {
+               attr.style == ast::AttrStyle::Inner && !attr.has_name(sym::test) {
                 emit_feature_err(&self.cx.parse_sess, sym::custom_inner_attributes,
                                  attr.span, GateIssue::Language,
                                  "non-builtin inner attributes are unstable");
@@ -1032,7 +1033,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
             feature_gate::check_attribute(attr, self.cx.parse_sess, features);
 
             // macros are expanded before any lint passes so this warning has to be hardcoded
-            if attr.item.path == sym::derive {
+            if attr.has_name(sym::derive) {
                 self.cx.struct_span_warn(attr.span, "`#[derive]` does nothing on macro invocations")
                     .note("this may become a hard error in a future release")
                     .emit();
@@ -1547,11 +1548,12 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
 
             let meta = attr::mk_list_item(Ident::with_dummy_span(sym::doc), items);
             *at = attr::Attribute {
-                item: AttrItem { path: meta.path, tokens: meta.kind.tokens(meta.span) },
+                kind: ast::AttrKind::Normal(
+                    AttrItem { path: meta.path, tokens: meta.kind.tokens(meta.span) },
+                ),
                 span: at.span,
                 id: at.id,
                 style: at.style,
-                is_sugared_doc: false,
             };
         } else {
             noop_visit_attribute(at, self)
diff --git a/src/libsyntax_expand/proc_macro.rs b/src/libsyntax_expand/proc_macro.rs
index 53cd4d3519f..1f4c481e3ea 100644
--- a/src/libsyntax_expand/proc_macro.rs
+++ b/src/libsyntax_expand/proc_macro.rs
@@ -181,7 +181,7 @@ impl<'a> Visitor<'a> for MarkAttrs<'a> {
 crate fn collect_derives(cx: &mut ExtCtxt<'_>, attrs: &mut Vec<ast::Attribute>) -> Vec<ast::Path> {
     let mut result = Vec::new();
     attrs.retain(|attr| {
-        if attr.item.path != sym::derive {
+        if !attr.has_name(sym::derive) {
             return true;
         }
         if !attr.is_meta_item_list() {
@@ -196,7 +196,7 @@ crate fn collect_derives(cx: &mut ExtCtxt<'_>, attrs: &mut Vec<ast::Attribute>)
         }
 
         let parse_derive_paths = |attr: &ast::Attribute| {
-            if attr.item.tokens.is_empty() {
+            if attr.get_normal_item().tokens.is_empty() {
                 return Ok(Vec::new());
             }
             parse::parse_in_attr(cx.parse_sess, attr, |p| p.parse_derive_paths())
diff --git a/src/libsyntax_ext/proc_macro_harness.rs b/src/libsyntax_ext/proc_macro_harness.rs
index bef91399927..792c97d8508 100644
--- a/src/libsyntax_ext/proc_macro_harness.rs
+++ b/src/libsyntax_ext/proc_macro_harness.rs
@@ -249,9 +249,11 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> {
         for attr in &item.attrs {
             if is_proc_macro_attr(&attr) {
                 if let Some(prev_attr) = found_attr {
-                    let path_str = pprust::path_to_string(&attr.item.path);
-                    let msg = if attr.item.path.segments[0].ident.name ==
-                                 prev_attr.item.path.segments[0].ident.name {
+                    let prev_item = prev_attr.get_normal_item();
+                    let item = attr.get_normal_item();
+                    let path_str = pprust::path_to_string(&item.path);
+                    let msg = if item.path.segments[0].ident.name ==
+                                 prev_item.path.segments[0].ident.name {
                         format!(
                             "only one `#[{}]` attribute is allowed on any given function",
                             path_str,
@@ -261,7 +263,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> {
                             "`#[{}]` and `#[{}]` attributes cannot both be applied
                             to the same function",
                             path_str,
-                            pprust::path_to_string(&prev_attr.item.path),
+                            pprust::path_to_string(&prev_item.path),
                         )
                     };
 
@@ -290,7 +292,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> {
         if !is_fn {
             let msg = format!(
                 "the `#[{}]` attribute may only be used on bare functions",
-                pprust::path_to_string(&attr.item.path),
+                pprust::path_to_string(&attr.get_normal_item().path),
             );
 
             self.handler.span_err(attr.span, &msg);
@@ -304,7 +306,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> {
         if !self.is_proc_macro_crate {
             let msg = format!(
                 "the `#[{}]` attribute is only usable with crates of the `proc-macro` crate type",
-                pprust::path_to_string(&attr.item.path),
+                pprust::path_to_string(&attr.get_normal_item().path),
             );
 
             self.handler.span_err(attr.span, &msg);
-- 
cgit 1.4.1-3-g733a5


From beddf67a4b1ce5f1e14a67690644690c4b1bcfaa Mon Sep 17 00:00:00 2001
From: Mazdak Farrokhzad <twingoow@gmail.com>
Date: Sun, 27 Oct 2019 23:14:35 +0100
Subject: parser: don't hardcode ABIs into grammar

---
 src/librustc/error_codes.rs                        |   1 +
 src/librustc/hir/lowering.rs                       |   2 +-
 src/librustc/hir/lowering/item.rs                  |  25 +-
 src/librustc_save_analysis/sig.rs                  |  26 +-
 src/libsyntax/ast.rs                               |  24 +-
 src/libsyntax/error_codes.rs                       |   1 -
 src/libsyntax/feature_gate/check.rs                |  63 ++---
 src/libsyntax/parse/parser.rs                      |  38 +--
 src/libsyntax/parse/parser/item.rs                 |  21 +-
 src/libsyntax/print/pprust.rs                      |  13 +-
 src/libsyntax/print/pprust/tests.rs                |   7 +-
 src/libsyntax_ext/deriving/generic/mod.rs          |  31 +--
 src/libsyntax_pos/symbol.rs                        |   1 +
 .../ui/feature-gated-feature-in-macro-arg.stderr   |   8 +-
 .../feature-gate-abi-msp430-interrupt.stderr       |   4 +-
 src/test/ui/feature-gates/feature-gate-abi.stderr  | 272 ++++++++++-----------
 .../feature-gate-abi_unadjusted.stderr             |   8 +-
 .../feature-gates/feature-gate-intrinsics.stderr   |  12 +-
 ...ature-gate-unboxed-closures-manual-impls.stderr |  16 +-
 .../feature-gate-unboxed-closures.stderr           |   8 +-
 20 files changed, 296 insertions(+), 285 deletions(-)

(limited to 'src/libsyntax/parse/parser/item.rs')

diff --git a/src/librustc/error_codes.rs b/src/librustc/error_codes.rs
index f5ff92e69bc..cf892127a30 100644
--- a/src/librustc/error_codes.rs
+++ b/src/librustc/error_codes.rs
@@ -2336,6 +2336,7 @@ the future, [RFC 2091] prohibits their implementation without a follow-up RFC.
     E0657, // `impl Trait` can only capture lifetimes bound at the fn level
     E0687, // in-band lifetimes cannot be used in `fn`/`Fn` syntax
     E0688, // in-band lifetimes cannot be mixed with explicit lifetime binders
+    E0703, // invalid ABI
 //  E0707, // multiple elided lifetimes used in arguments of `async fn`
     E0708, // `async` non-`move` closures with parameters are not currently
            // supported
diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index 230fbb16b87..6344c7a233c 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -1216,7 +1216,7 @@ impl<'a> LoweringContext<'a> {
                                     ImplTraitContext::disallowed(),
                                 ),
                                 unsafety: this.lower_unsafety(f.unsafety),
-                                abi: f.abi,
+                                abi: this.lower_abi(f.abi),
                                 decl: this.lower_fn_decl(&f.decl, None, false, None),
                                 param_names: this.lower_fn_params_to_names(&f.decl),
                             }))
diff --git a/src/librustc/hir/lowering/item.rs b/src/librustc/hir/lowering/item.rs
index f1b999cdd6f..5fe463d783f 100644
--- a/src/librustc/hir/lowering/item.rs
+++ b/src/librustc/hir/lowering/item.rs
@@ -12,6 +12,7 @@ use crate::hir::def::{Res, DefKind};
 use crate::util::nodemap::NodeMap;
 
 use rustc_data_structures::thin_vec::ThinVec;
+use rustc_target::spec::abi;
 
 use std::collections::BTreeSet;
 use smallvec::SmallVec;
@@ -735,7 +736,7 @@ impl LoweringContext<'_> {
 
     fn lower_foreign_mod(&mut self, fm: &ForeignMod) -> hir::ForeignMod {
         hir::ForeignMod {
-            abi: fm.abi,
+            abi: self.lower_abi(fm.abi),
             items: fm.items
                 .iter()
                 .map(|x| self.lower_foreign_item(x))
@@ -1291,10 +1292,30 @@ impl LoweringContext<'_> {
             unsafety: self.lower_unsafety(h.unsafety),
             asyncness: self.lower_asyncness(h.asyncness.node),
             constness: self.lower_constness(h.constness),
-            abi: h.abi,
+            abi: self.lower_abi(h.abi),
         }
     }
 
+    pub(super) fn lower_abi(&mut self, abi: Abi) -> abi::Abi {
+        abi::lookup(&abi.symbol.as_str()).unwrap_or_else(|| {
+            self.error_on_invalid_abi(abi);
+            abi::Abi::Rust
+        })
+    }
+
+    fn error_on_invalid_abi(&self, abi: Abi) {
+        struct_span_err!(
+            self.sess,
+            abi.span,
+            E0703,
+            "invalid ABI: found `{}`",
+            abi.symbol
+        )
+        .span_label(abi.span, "invalid ABI")
+        .help(&format!("valid ABIs: {}", abi::all_names().join(", ")))
+        .emit();
+    }
+
     pub(super) fn lower_unsafety(&mut self, u: Unsafety) -> hir::Unsafety {
         match u {
             Unsafety::Unsafe => hir::Unsafety::Unsafe,
diff --git a/src/librustc_save_analysis/sig.rs b/src/librustc_save_analysis/sig.rs
index 203bd4d4167..019e92717b5 100644
--- a/src/librustc_save_analysis/sig.rs
+++ b/src/librustc_save_analysis/sig.rs
@@ -32,7 +32,7 @@ use rls_data::{SigElement, Signature};
 use rustc::hir::def::{Res, DefKind};
 use syntax::ast::{self, NodeId};
 use syntax::print::pprust;
-
+use syntax_pos::sym;
 
 pub fn item_signature(item: &ast::Item, scx: &SaveContext<'_, '_>) -> Option<Signature> {
     if !scx.config.signatures {
@@ -157,6 +157,12 @@ fn text_sig(text: String) -> Signature {
     }
 }
 
+fn push_abi(text: &mut String, abi: ast::Abi) {
+    if abi.symbol != sym::Rust {
+        text.push_str(&format!("extern \"{}\" ", abi.symbol));
+    }
+}
+
 impl Sig for ast::Ty {
     fn make(&self, offset: usize, _parent_id: Option<NodeId>, scx: &SaveContext<'_, '_>) -> Result {
         let id = Some(self.id);
@@ -231,11 +237,7 @@ impl Sig for ast::Ty {
                 if f.unsafety == ast::Unsafety::Unsafe {
                     text.push_str("unsafe ");
                 }
-                if f.abi != rustc_target::spec::abi::Abi::Rust {
-                    text.push_str("extern");
-                    text.push_str(&f.abi.to_string());
-                    text.push(' ');
-                }
+                push_abi(&mut text, f.abi);
                 text.push_str("fn(");
 
                 let mut defs = vec![];
@@ -385,11 +387,7 @@ impl Sig for ast::Item {
                 if header.unsafety == ast::Unsafety::Unsafe {
                     text.push_str("unsafe ");
                 }
-                if header.abi != rustc_target::spec::abi::Abi::Rust {
-                    text.push_str("extern");
-                    text.push_str(&header.abi.to_string());
-                    text.push(' ');
-                }
+                push_abi(&mut text, header.abi);
                 text.push_str("fn ");
 
                 let mut sig = name_and_generics(text, offset, generics, self.id, self.ident, scx)?;
@@ -948,11 +946,7 @@ fn make_method_signature(
     if m.header.unsafety == ast::Unsafety::Unsafe {
         text.push_str("unsafe ");
     }
-    if m.header.abi != rustc_target::spec::abi::Abi::Rust {
-        text.push_str("extern");
-        text.push_str(&m.header.abi.to_string());
-        text.push(' ');
-    }
+    push_abi(&mut text, m.header.abi);
     text.push_str("fn ");
 
     let mut sig = name_and_generics(text, 0, generics, id, ident, scx)?;
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 2392b809150..f761c35cd5c 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -38,7 +38,6 @@ use rustc_data_structures::sync::Lrc;
 use rustc_data_structures::thin_vec::ThinVec;
 use rustc_index::vec::Idx;
 use rustc_serialize::{self, Decoder, Encoder};
-use rustc_target::spec::abi::Abi;
 
 #[cfg(target_arch = "x86_64")]
 use rustc_data_structures::static_assert_size;
@@ -2358,6 +2357,27 @@ impl Item {
     }
 }
 
+/// A reference to an ABI.
+///
+/// In AST our notion of an ABI is still syntactic unlike in `rustc_target::spec::abi::Abi`.
+#[derive(Clone, Copy, RustcEncodable, RustcDecodable, Debug, PartialEq)]
+pub struct Abi {
+    pub symbol: Symbol,
+    pub span: Span,
+}
+
+impl Abi {
+    pub fn new(symbol: Symbol, span: Span) -> Self {
+        Self { symbol, span }
+    }
+}
+
+impl Default for Abi {
+    fn default() -> Self {
+        Self::new(sym::Rust, DUMMY_SP)
+    }
+}
+
 /// A function header.
 ///
 /// All the information between the visibility and the name of the function is
@@ -2376,7 +2396,7 @@ impl Default for FnHeader {
             unsafety: Unsafety::Normal,
             asyncness: dummy_spanned(IsAsync::NotAsync),
             constness: dummy_spanned(Constness::NotConst),
-            abi: Abi::Rust,
+            abi: Abi::default(),
         }
     }
 }
diff --git a/src/libsyntax/error_codes.rs b/src/libsyntax/error_codes.rs
index 941df5ea570..c23c8d65a7f 100644
--- a/src/libsyntax/error_codes.rs
+++ b/src/libsyntax/error_codes.rs
@@ -540,6 +540,5 @@ equivalent in Rust would be to use macros directly.
     E0630,
     E0693, // incorrect `repr(align)` attribute format
 //  E0694, // an unknown tool name found in scoped attributes
-    E0703, // invalid ABI
     E0717, // rustc_promotable without stability attribute
 }
diff --git a/src/libsyntax/feature_gate/check.rs b/src/libsyntax/feature_gate/check.rs
index b7e75ff3a7e..213e9680524 100644
--- a/src/libsyntax/feature_gate/check.rs
+++ b/src/libsyntax/feature_gate/check.rs
@@ -18,7 +18,6 @@ use crate::tokenstream::TokenTree;
 
 use errors::{Applicability, DiagnosticBuilder, Handler};
 use rustc_data_structures::fx::FxHashMap;
-use rustc_target::spec::abi::Abi;
 use syntax_pos::{Span, DUMMY_SP, MultiSpan};
 use log::debug;
 
@@ -192,62 +191,70 @@ macro_rules! gate_feature_post {
 }
 
 impl<'a> PostExpansionVisitor<'a> {
-    fn check_abi(&self, abi: Abi, span: Span) {
-        match abi {
-            Abi::RustIntrinsic => {
+    fn check_abi(&self, abi: ast::Abi) {
+        let ast::Abi { symbol, span } = abi;
+
+        match &*symbol.as_str() {
+            // Stable
+            "Rust" |
+            "C" |
+            "cdecl" |
+            "stdcall" |
+            "fastcall" |
+            "aapcs" |
+            "win64" |
+            "sysv64" |
+            "system" => {}
+            "rust-intrinsic" => {
                 gate_feature_post!(&self, intrinsics, span,
                                    "intrinsics are subject to change");
             },
-            Abi::PlatformIntrinsic => {
+            "platform-intrinsic" => {
                 gate_feature_post!(&self, platform_intrinsics, span,
                                    "platform intrinsics are experimental and possibly buggy");
             },
-            Abi::Vectorcall => {
+            "vectorcall" => {
                 gate_feature_post!(&self, abi_vectorcall, span,
                                    "vectorcall is experimental and subject to change");
             },
-            Abi::Thiscall => {
+            "thiscall" => {
                 gate_feature_post!(&self, abi_thiscall, span,
                                    "thiscall is experimental and subject to change");
             },
-            Abi::RustCall => {
+            "rust-call" => {
                 gate_feature_post!(&self, unboxed_closures, span,
                                    "rust-call ABI is subject to change");
             },
-            Abi::PtxKernel => {
+            "ptx-kernel" => {
                 gate_feature_post!(&self, abi_ptx, span,
                                    "PTX ABIs are experimental and subject to change");
             },
-            Abi::Unadjusted => {
+            "unadjusted" => {
                 gate_feature_post!(&self, abi_unadjusted, span,
                                    "unadjusted ABI is an implementation detail and perma-unstable");
             },
-            Abi::Msp430Interrupt => {
+            "msp430-interrupt" => {
                 gate_feature_post!(&self, abi_msp430_interrupt, span,
                                    "msp430-interrupt ABI is experimental and subject to change");
             },
-            Abi::X86Interrupt => {
+            "x86-interrupt" => {
                 gate_feature_post!(&self, abi_x86_interrupt, span,
                                    "x86-interrupt ABI is experimental and subject to change");
             },
-            Abi::AmdGpuKernel => {
+            "amdgpu-kernel" => {
                 gate_feature_post!(&self, abi_amdgpu_kernel, span,
                                    "amdgpu-kernel ABI is experimental and subject to change");
             },
-            Abi::EfiApi => {
+            "efiapi" => {
                 gate_feature_post!(&self, abi_efiapi, span,
                                    "efiapi ABI is experimental and subject to change");
             },
-            // Stable
-            Abi::Cdecl |
-            Abi::Stdcall |
-            Abi::Fastcall |
-            Abi::Aapcs |
-            Abi::Win64 |
-            Abi::SysV64 |
-            Abi::Rust |
-            Abi::C |
-            Abi::System => {}
+            abi => {
+                self.parse_sess.span_diagnostic.delay_span_bug(
+                    span,
+                    &format!("unrecognized ABI not caught in lowering: {}", abi),
+                )
+            }
         }
     }
 
@@ -373,7 +380,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
     fn visit_item(&mut self, i: &'a ast::Item) {
         match i.kind {
             ast::ItemKind::ForeignMod(ref foreign_module) => {
-                self.check_abi(foreign_module.abi, i.span);
+                self.check_abi(foreign_module.abi);
             }
 
             ast::ItemKind::Fn(..) => {
@@ -503,7 +510,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
     fn visit_ty(&mut self, ty: &'a ast::Ty) {
         match ty.kind {
             ast::TyKind::BareFn(ref bare_fn_ty) => {
-                self.check_abi(bare_fn_ty.abi, ty.span);
+                self.check_abi(bare_fn_ty.abi);
             }
             ast::TyKind::Never => {
                 gate_feature_post!(&self, never_type, ty.span,
@@ -597,7 +604,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             // Stability of const fn methods are covered in
             // `visit_trait_item` and `visit_impl_item` below; this is
             // because default methods don't pass through this point.
-            self.check_abi(header.abi, span);
+            self.check_abi(header.abi);
         }
 
         if fn_decl.c_variadic() {
@@ -631,7 +638,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
         match ti.kind {
             ast::TraitItemKind::Method(ref sig, ref block) => {
                 if block.is_none() {
-                    self.check_abi(sig.header.abi, ti.span);
+                    self.check_abi(sig.header.abi);
                 }
                 if sig.decl.c_variadic() {
                     gate_feature_post!(&self, c_variadic, ti.span,
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 7652c730e51..382c1a517aa 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -12,7 +12,7 @@ mod diagnostics;
 use diagnostics::Error;
 
 use crate::ast::{
-    self, DUMMY_NODE_ID, AttrStyle, Attribute, CrateSugar, Ident,
+    self, Abi, DUMMY_NODE_ID, AttrStyle, Attribute, CrateSugar, Ident,
     IsAsync, MacDelimiter, Mutability, StrStyle, Visibility, VisibilityKind, Unsafety,
 };
 use crate::parse::{PResult, Directory, DirectoryOwnership};
@@ -28,7 +28,6 @@ use crate::tokenstream::{self, DelimSpan, TokenTree, TokenStream, TreeAndJoint};
 use crate::ThinVec;
 
 use errors::{Applicability, DiagnosticBuilder, DiagnosticId, FatalError};
-use rustc_target::spec::abi::{self, Abi};
 use syntax_pos::{Span, BytePos, DUMMY_SP, FileName};
 use log::debug;
 
@@ -1208,48 +1207,27 @@ impl<'a> Parser<'a> {
 
     /// Parses `extern` followed by an optional ABI string, or nothing.
     fn parse_extern_abi(&mut self) -> PResult<'a, Abi> {
-        if self.eat_keyword(kw::Extern) {
-            Ok(self.parse_opt_abi()?.unwrap_or(Abi::C))
+        Ok(if self.eat_keyword(kw::Extern) {
+            let ext_sp = self.prev_span;
+            self.parse_opt_abi()?.unwrap_or_else(|| Abi::new(sym::C, ext_sp))
         } else {
-            Ok(Abi::Rust)
-        }
+            Abi::default()
+        })
     }
 
-    /// Parses a string as an ABI spec on an extern type or module. Consumes
-    /// the `extern` keyword, if one is found.
+    /// Parses a string as an ABI spec on an extern type or module.
     fn parse_opt_abi(&mut self) -> PResult<'a, Option<Abi>> {
         match self.token.kind {
             token::Literal(token::Lit { kind: token::Str, symbol, suffix }) |
             token::Literal(token::Lit { kind: token::StrRaw(..), symbol, suffix }) => {
                 self.expect_no_suffix(self.token.span, "an ABI spec", suffix);
                 self.bump();
-                match abi::lookup(&symbol.as_str()) {
-                    Some(abi) => Ok(Some(abi)),
-                    None => {
-                        self.error_on_invalid_abi(symbol);
-                        Ok(None)
-                    }
-                }
+                Ok(Some(Abi::new(symbol, self.prev_span)))
             }
             _ => Ok(None),
         }
     }
 
-    /// Emit an error where `symbol` is an invalid ABI.
-    fn error_on_invalid_abi(&self, symbol: Symbol) {
-        let prev_span = self.prev_span;
-        struct_span_err!(
-            self.sess.span_diagnostic,
-            prev_span,
-            E0703,
-            "invalid ABI: found `{}`",
-            symbol
-        )
-        .span_label(prev_span, "invalid ABI")
-        .help(&format!("valid ABIs: {}", abi::all_names().join(", ")))
-        .emit();
-    }
-
     /// We are parsing `async fn`. If we are on Rust 2015, emit an error.
     fn ban_async_in_2015(&self, async_span: Span) {
         if async_span.rust_2015() {
diff --git a/src/libsyntax/parse/parser/item.rs b/src/libsyntax/parse/parser/item.rs
index cc6235c6fc7..76411e7cf13 100644
--- a/src/libsyntax/parse/parser/item.rs
+++ b/src/libsyntax/parse/parser/item.rs
@@ -3,7 +3,7 @@ use super::diagnostics::{Error, dummy_arg, ConsumeClosingDelim};
 
 use crate::maybe_whole;
 use crate::ptr::P;
-use crate::ast::{self, DUMMY_NODE_ID, Ident, Attribute, AttrKind, AttrStyle, AnonConst, Item};
+use crate::ast::{self, Abi, DUMMY_NODE_ID, Ident, Attribute, AttrKind, AttrStyle, AnonConst, Item};
 use crate::ast::{ItemKind, ImplItem, ImplItemKind, TraitItem, TraitItemKind, UseTree, UseTreeKind};
 use crate::ast::{PathSegment, IsAuto, Constness, IsAsync, Unsafety, Defaultness};
 use crate::ast::{Visibility, VisibilityKind, Mutability, FnHeader, ForeignItem, ForeignItemKind};
@@ -17,7 +17,6 @@ use crate::ThinVec;
 
 use log::debug;
 use std::mem;
-use rustc_target::spec::abi::Abi;
 use errors::{Applicability, DiagnosticBuilder, DiagnosticId, StashKey};
 use syntax_pos::BytePos;
 
@@ -111,7 +110,7 @@ impl<'a> Parser<'a> {
                 return Ok(Some(self.parse_item_extern_crate(lo, vis, attrs)?));
             }
 
-            let opt_abi = self.parse_opt_abi()?;
+            let abi = self.parse_opt_abi()?.unwrap_or_else(|| Abi::new(sym::C, extern_sp));
 
             if self.eat_keyword(kw::Fn) {
                 // EXTERN FUNCTION ITEM
@@ -120,12 +119,12 @@ impl<'a> Parser<'a> {
                     unsafety: Unsafety::Normal,
                     asyncness: respan(fn_span, IsAsync::NotAsync),
                     constness: respan(fn_span, Constness::NotConst),
-                    abi: opt_abi.unwrap_or(Abi::C),
+                    abi,
                 };
                 return self.parse_item_fn(lo, vis, attrs, header);
             } else if self.check(&token::OpenDelim(token::Brace)) {
                 return Ok(Some(
-                    self.parse_item_foreign_mod(lo, opt_abi, vis, attrs, extern_sp)?,
+                    self.parse_item_foreign_mod(lo, abi, vis, attrs, extern_sp)?,
                 ));
             }
 
@@ -201,7 +200,7 @@ impl<'a> Parser<'a> {
                     unsafety,
                     asyncness,
                     constness: respan(fn_span, Constness::NotConst),
-                    abi: Abi::Rust,
+                    abi: Abi::new(sym::Rust, fn_span),
                 };
                 return self.parse_item_fn(lo, vis, attrs, header);
             }
@@ -238,7 +237,7 @@ impl<'a> Parser<'a> {
                 unsafety: Unsafety::Normal,
                 asyncness: respan(fn_span, IsAsync::NotAsync),
                 constness: respan(fn_span, Constness::NotConst),
-                abi: Abi::Rust,
+                abi: Abi::new(sym::Rust, fn_span),
             };
             return self.parse_item_fn(lo, vis, attrs, header);
         }
@@ -1115,15 +1114,13 @@ impl<'a> Parser<'a> {
     fn parse_item_foreign_mod(
         &mut self,
         lo: Span,
-        opt_abi: Option<Abi>,
+        abi: Abi,
         visibility: Visibility,
         mut attrs: Vec<Attribute>,
         extern_sp: Span,
     ) -> PResult<'a, P<Item>> {
         self.expect(&token::OpenDelim(token::Brace))?;
 
-        let abi = opt_abi.unwrap_or(Abi::C);
-
         attrs.extend(self.parse_inner_attributes()?);
 
         let mut foreign_items = vec![];
@@ -1801,7 +1798,7 @@ impl<'a> Parser<'a> {
     ) -> PResult<'a, Option<P<Item>>> {
         let (ident, decl, generics) = self.parse_fn_sig(ParamCfg {
             is_self_allowed: false,
-            allow_c_variadic: header.abi == Abi::C && header.unsafety == Unsafety::Unsafe,
+            allow_c_variadic: header.abi.symbol == sym::C && header.unsafety == Unsafety::Unsafe,
             is_name_required: |_| true,
         })?;
         let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
@@ -1930,7 +1927,7 @@ impl<'a> Parser<'a> {
         let asyncness = respan(self.prev_span, asyncness);
         let unsafety = self.parse_unsafety();
         let (constness, unsafety, abi) = if is_const_fn {
-            (respan(const_span, Constness::Const), unsafety, Abi::Rust)
+            (respan(const_span, Constness::Const), unsafety, Abi::default())
         } else {
             let abi = self.parse_extern_abi()?;
             (respan(self.prev_span, Constness::NotConst), unsafety, abi)
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index c8afe8a1ff4..1d59c13a9d0 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -14,7 +14,6 @@ use crate::sess::ParseSess;
 use crate::symbol::{kw, sym};
 use crate::tokenstream::{self, TokenStream, TokenTree};
 
-use rustc_target::spec::abi::{self, Abi};
 use syntax_pos::{self, BytePos};
 use syntax_pos::{FileName, Span};
 
@@ -1230,7 +1229,7 @@ impl<'a> State<'a> {
             }
             ast::ItemKind::ForeignMod(ref nmod) => {
                 self.head("extern");
-                self.word_nbsp(nmod.abi.to_string());
+                self.print_abi(nmod.abi);
                 self.bopen();
                 self.print_foreign_mod(nmod, &item.attrs);
                 self.bclose(item.span);
@@ -2823,7 +2822,7 @@ impl<'a> State<'a> {
     }
 
     crate fn print_ty_fn(&mut self,
-                       abi: abi::Abi,
+                       abi: ast::Abi,
                        unsafety: ast::Unsafety,
                        decl: &ast::FnDecl,
                        name: Option<ast::Ident>,
@@ -2884,14 +2883,18 @@ impl<'a> State<'a> {
         self.print_asyncness(header.asyncness.node);
         self.print_unsafety(header.unsafety);
 
-        if header.abi != Abi::Rust {
+        if header.abi.symbol != sym::Rust {
             self.word_nbsp("extern");
-            self.word_nbsp(header.abi.to_string());
+            self.print_abi(header.abi);
         }
 
         self.s.word("fn")
     }
 
+    fn print_abi(&mut self, abi: ast::Abi) {
+        self.word_nbsp(format!("\"{}\"", abi.symbol));
+    }
+
     crate fn print_unsafety(&mut self, s: ast::Unsafety) {
         match s {
             ast::Unsafety::Normal => {},
diff --git a/src/libsyntax/print/pprust/tests.rs b/src/libsyntax/print/pprust/tests.rs
index faa70edbfa2..2c6dd0fb1c6 100644
--- a/src/libsyntax/print/pprust/tests.rs
+++ b/src/libsyntax/print/pprust/tests.rs
@@ -34,12 +34,7 @@ fn test_fun_to_string() {
         assert_eq!(
             fun_to_string(
                 &decl,
-                ast::FnHeader {
-                    unsafety: ast::Unsafety::Normal,
-                    constness: source_map::dummy_spanned(ast::Constness::NotConst),
-                    asyncness: source_map::dummy_spanned(ast::IsAsync::NotAsync),
-                    abi: Abi::Rust,
-                },
+                ast::FnHeader::default(),
                 abba_ident,
                 &generics
             ),
diff --git a/src/libsyntax_ext/deriving/generic/mod.rs b/src/libsyntax_ext/deriving/generic/mod.rs
index 2e5ae235893..b18fd50ae76 100644
--- a/src/libsyntax_ext/deriving/generic/mod.rs
+++ b/src/libsyntax_ext/deriving/generic/mod.rs
@@ -182,8 +182,7 @@ use std::iter;
 use std::vec;
 
 use rustc_data_structures::thin_vec::ThinVec;
-use rustc_target::spec::abi::Abi;
-use syntax::ast::{self, BinOpKind, EnumDef, Expr, Generics, Ident, PatKind};
+use syntax::ast::{self, Abi, BinOpKind, EnumDef, Expr, Generics, Ident, PatKind};
 use syntax::ast::{VariantData, GenericParamKind, GenericArg};
 use syntax::attr;
 use syntax::source_map::respan;
@@ -738,7 +737,7 @@ impl<'a> TraitDef<'a> {
                                          self,
                                          type_ident,
                                          generics,
-                                         Abi::Rust,
+                                         sym::Rust,
                                          explicit_self,
                                          tys,
                                          body)
@@ -793,7 +792,7 @@ impl<'a> TraitDef<'a> {
                                          self,
                                          type_ident,
                                          generics,
-                                         Abi::Rust,
+                                         sym::Rust,
                                          explicit_self,
                                          tys,
                                          body)
@@ -919,7 +918,7 @@ impl<'a> MethodDef<'a> {
                      trait_: &TraitDef<'_>,
                      type_ident: Ident,
                      generics: &Generics,
-                     abi: Abi,
+                     abi: Symbol,
                      explicit_self: Option<ast::ExplicitSelf>,
                      arg_types: Vec<(Ident, P<ast::Ty>)>,
                      body: P<Expr>)
@@ -949,23 +948,27 @@ impl<'a> MethodDef<'a> {
             ast::Unsafety::Normal
         };
 
+        let trait_lo_sp = trait_.span.shrink_to_lo();
+
+        let sig = ast::MethodSig {
+            header: ast::FnHeader {
+                unsafety,
+                abi: Abi::new(abi, trait_lo_sp),
+                ..ast::FnHeader::default()
+            },
+            decl: fn_decl,
+        };
+
         // Create the method.
         ast::ImplItem {
             id: ast::DUMMY_NODE_ID,
             attrs: self.attributes.clone(),
             generics: fn_generics,
             span: trait_.span,
-            vis: respan(trait_.span.shrink_to_lo(), ast::VisibilityKind::Inherited),
+            vis: respan(trait_lo_sp, ast::VisibilityKind::Inherited),
             defaultness: ast::Defaultness::Final,
             ident: method_ident,
-            kind: ast::ImplItemKind::Method(ast::MethodSig {
-                                                header: ast::FnHeader {
-                                                    unsafety, abi,
-                                                    ..ast::FnHeader::default()
-                                                },
-                                                decl: fn_decl,
-                                            },
-                                            body_block),
+            kind: ast::ImplItemKind::Method(sig, body_block),
             tokens: None,
         }
     }
diff --git a/src/libsyntax_pos/symbol.rs b/src/libsyntax_pos/symbol.rs
index 3f7b3e5b3d8..2bdd8eacd11 100644
--- a/src/libsyntax_pos/symbol.rs
+++ b/src/libsyntax_pos/symbol.rs
@@ -563,6 +563,7 @@ symbols! {
         rust_2018_preview,
         rust_begin_unwind,
         rustc,
+        Rust,
         RustcDecodable,
         RustcEncodable,
         rustc_allocator,
diff --git a/src/test/ui/feature-gated-feature-in-macro-arg.stderr b/src/test/ui/feature-gated-feature-in-macro-arg.stderr
index 5ee05154c3a..218e0292776 100644
--- a/src/test/ui/feature-gated-feature-in-macro-arg.stderr
+++ b/src/test/ui/feature-gated-feature-in-macro-arg.stderr
@@ -1,10 +1,8 @@
 error[E0658]: intrinsics are subject to change
-  --> $DIR/feature-gated-feature-in-macro-arg.rs:8:9
+  --> $DIR/feature-gated-feature-in-macro-arg.rs:8:16
    |
-LL | /         extern "rust-intrinsic" {
-LL | |             fn atomic_fence();
-LL | |         }
-   | |_________^
+LL |         extern "rust-intrinsic" {
+   |                ^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(intrinsics)]` to the crate attributes to enable
 
diff --git a/src/test/ui/feature-gates/feature-gate-abi-msp430-interrupt.stderr b/src/test/ui/feature-gates/feature-gate-abi-msp430-interrupt.stderr
index 0d2e355535d..d58a2d91b2b 100644
--- a/src/test/ui/feature-gates/feature-gate-abi-msp430-interrupt.stderr
+++ b/src/test/ui/feature-gates/feature-gate-abi-msp430-interrupt.stderr
@@ -1,8 +1,8 @@
 error[E0658]: msp430-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi-msp430-interrupt.rs:4:1
+  --> $DIR/feature-gate-abi-msp430-interrupt.rs:4:8
    |
 LL | extern "msp430-interrupt" fn foo() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38487
    = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
diff --git a/src/test/ui/feature-gates/feature-gate-abi.stderr b/src/test/ui/feature-gates/feature-gate-abi.stderr
index 0f2622f1065..6db6cb49cef 100644
--- a/src/test/ui/feature-gates/feature-gate-abi.stderr
+++ b/src/test/ui/feature-gates/feature-gate-abi.stderr
@@ -1,591 +1,591 @@
 error[E0658]: intrinsics are subject to change
-  --> $DIR/feature-gate-abi.rs:13:1
+  --> $DIR/feature-gate-abi.rs:13:8
    |
 LL | extern "rust-intrinsic" fn f1() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(intrinsics)]` to the crate attributes to enable
 
 error[E0658]: platform intrinsics are experimental and possibly buggy
-  --> $DIR/feature-gate-abi.rs:15:1
+  --> $DIR/feature-gate-abi.rs:15:8
    |
 LL | extern "platform-intrinsic" fn f2() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/27731
    = help: add `#![feature(platform_intrinsics)]` to the crate attributes to enable
 
 error[E0658]: vectorcall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:17:1
+  --> $DIR/feature-gate-abi.rs:17:8
    |
 LL | extern "vectorcall" fn f3() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^
    |
    = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
 
 error[E0658]: rust-call ABI is subject to change
-  --> $DIR/feature-gate-abi.rs:18:1
+  --> $DIR/feature-gate-abi.rs:18:8
    |
 LL | extern "rust-call" fn f4() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/29625
    = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
 
 error[E0658]: msp430-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:19:1
+  --> $DIR/feature-gate-abi.rs:19:8
    |
 LL | extern "msp430-interrupt" fn f5() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38487
    = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
 
 error[E0658]: PTX ABIs are experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:20:1
+  --> $DIR/feature-gate-abi.rs:20:8
    |
 LL | extern "ptx-kernel" fn f6() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38788
    = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
 
 error[E0658]: x86-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:21:1
+  --> $DIR/feature-gate-abi.rs:21:8
    |
 LL | extern "x86-interrupt" fn f7() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/40180
    = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
 
 error[E0658]: thiscall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:22:1
+  --> $DIR/feature-gate-abi.rs:22:8
    |
 LL | extern "thiscall" fn f8() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^
    |
    = help: add `#![feature(abi_thiscall)]` to the crate attributes to enable
 
 error[E0658]: amdgpu-kernel ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:23:1
+  --> $DIR/feature-gate-abi.rs:23:8
    |
 LL | extern "amdgpu-kernel" fn f9() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/51575
    = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
 
 error[E0658]: efiapi ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:24:1
+  --> $DIR/feature-gate-abi.rs:24:8
    |
 LL | extern "efiapi" fn f10() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/65815
    = help: add `#![feature(abi_efiapi)]` to the crate attributes to enable
 
 error[E0658]: intrinsics are subject to change
-  --> $DIR/feature-gate-abi.rs:28:5
+  --> $DIR/feature-gate-abi.rs:28:12
    |
 LL |     extern "rust-intrinsic" fn m1();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(intrinsics)]` to the crate attributes to enable
 
 error[E0658]: platform intrinsics are experimental and possibly buggy
-  --> $DIR/feature-gate-abi.rs:30:5
+  --> $DIR/feature-gate-abi.rs:30:12
    |
 LL |     extern "platform-intrinsic" fn m2();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/27731
    = help: add `#![feature(platform_intrinsics)]` to the crate attributes to enable
 
 error[E0658]: vectorcall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:32:5
+  --> $DIR/feature-gate-abi.rs:32:12
    |
 LL |     extern "vectorcall" fn m3();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^
    |
    = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
 
 error[E0658]: rust-call ABI is subject to change
-  --> $DIR/feature-gate-abi.rs:33:5
+  --> $DIR/feature-gate-abi.rs:33:12
    |
 LL |     extern "rust-call" fn m4();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/29625
    = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
 
 error[E0658]: msp430-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:34:5
+  --> $DIR/feature-gate-abi.rs:34:12
    |
 LL |     extern "msp430-interrupt" fn m5();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38487
    = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
 
 error[E0658]: PTX ABIs are experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:35:5
+  --> $DIR/feature-gate-abi.rs:35:12
    |
 LL |     extern "ptx-kernel" fn m6();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38788
    = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
 
 error[E0658]: x86-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:36:5
+  --> $DIR/feature-gate-abi.rs:36:12
    |
 LL |     extern "x86-interrupt" fn m7();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/40180
    = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
 
 error[E0658]: thiscall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:37:5
+  --> $DIR/feature-gate-abi.rs:37:12
    |
 LL |     extern "thiscall" fn m8();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^
    |
    = help: add `#![feature(abi_thiscall)]` to the crate attributes to enable
 
 error[E0658]: amdgpu-kernel ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:38:5
+  --> $DIR/feature-gate-abi.rs:38:12
    |
 LL |     extern "amdgpu-kernel" fn m9();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/51575
    = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
 
 error[E0658]: efiapi ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:39:5
+  --> $DIR/feature-gate-abi.rs:39:12
    |
 LL |     extern "efiapi" fn m10();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/65815
    = help: add `#![feature(abi_efiapi)]` to the crate attributes to enable
 
 error[E0658]: vectorcall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:41:5
+  --> $DIR/feature-gate-abi.rs:41:12
    |
 LL |     extern "vectorcall" fn dm3() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^
    |
    = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
 
 error[E0658]: rust-call ABI is subject to change
-  --> $DIR/feature-gate-abi.rs:42:5
+  --> $DIR/feature-gate-abi.rs:42:12
    |
 LL |     extern "rust-call" fn dm4() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/29625
    = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
 
 error[E0658]: msp430-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:43:5
+  --> $DIR/feature-gate-abi.rs:43:12
    |
 LL |     extern "msp430-interrupt" fn dm5() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38487
    = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
 
 error[E0658]: PTX ABIs are experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:44:5
+  --> $DIR/feature-gate-abi.rs:44:12
    |
 LL |     extern "ptx-kernel" fn dm6() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38788
    = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
 
 error[E0658]: x86-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:45:5
+  --> $DIR/feature-gate-abi.rs:45:12
    |
 LL |     extern "x86-interrupt" fn dm7() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/40180
    = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
 
 error[E0658]: thiscall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:46:5
+  --> $DIR/feature-gate-abi.rs:46:12
    |
 LL |     extern "thiscall" fn dm8() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^
    |
    = help: add `#![feature(abi_thiscall)]` to the crate attributes to enable
 
 error[E0658]: amdgpu-kernel ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:47:5
+  --> $DIR/feature-gate-abi.rs:47:12
    |
 LL |     extern "amdgpu-kernel" fn dm9() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/51575
    = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
 
 error[E0658]: efiapi ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:48:5
+  --> $DIR/feature-gate-abi.rs:48:12
    |
 LL |     extern "efiapi" fn dm10() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/65815
    = help: add `#![feature(abi_efiapi)]` to the crate attributes to enable
 
 error[E0658]: intrinsics are subject to change
-  --> $DIR/feature-gate-abi.rs:55:5
+  --> $DIR/feature-gate-abi.rs:55:12
    |
 LL |     extern "rust-intrinsic" fn m1() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(intrinsics)]` to the crate attributes to enable
 
 error[E0658]: platform intrinsics are experimental and possibly buggy
-  --> $DIR/feature-gate-abi.rs:57:5
+  --> $DIR/feature-gate-abi.rs:57:12
    |
 LL |     extern "platform-intrinsic" fn m2() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/27731
    = help: add `#![feature(platform_intrinsics)]` to the crate attributes to enable
 
 error[E0658]: vectorcall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:59:5
+  --> $DIR/feature-gate-abi.rs:59:12
    |
 LL |     extern "vectorcall" fn m3() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^
    |
    = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
 
 error[E0658]: rust-call ABI is subject to change
-  --> $DIR/feature-gate-abi.rs:60:5
+  --> $DIR/feature-gate-abi.rs:60:12
    |
 LL |     extern "rust-call" fn m4() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/29625
    = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
 
 error[E0658]: msp430-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:61:5
+  --> $DIR/feature-gate-abi.rs:61:12
    |
 LL |     extern "msp430-interrupt" fn m5() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38487
    = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
 
 error[E0658]: PTX ABIs are experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:62:5
+  --> $DIR/feature-gate-abi.rs:62:12
    |
 LL |     extern "ptx-kernel" fn m6() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38788
    = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
 
 error[E0658]: x86-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:63:5
+  --> $DIR/feature-gate-abi.rs:63:12
    |
 LL |     extern "x86-interrupt" fn m7() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/40180
    = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
 
 error[E0658]: thiscall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:64:5
+  --> $DIR/feature-gate-abi.rs:64:12
    |
 LL |     extern "thiscall" fn m8() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^
    |
    = help: add `#![feature(abi_thiscall)]` to the crate attributes to enable
 
 error[E0658]: amdgpu-kernel ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:65:5
+  --> $DIR/feature-gate-abi.rs:65:12
    |
 LL |     extern "amdgpu-kernel" fn m9() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/51575
    = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
 
 error[E0658]: efiapi ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:66:5
+  --> $DIR/feature-gate-abi.rs:66:12
    |
 LL |     extern "efiapi" fn m10() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/65815
    = help: add `#![feature(abi_efiapi)]` to the crate attributes to enable
 
 error[E0658]: intrinsics are subject to change
-  --> $DIR/feature-gate-abi.rs:71:5
+  --> $DIR/feature-gate-abi.rs:71:12
    |
 LL |     extern "rust-intrinsic" fn im1() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(intrinsics)]` to the crate attributes to enable
 
 error[E0658]: platform intrinsics are experimental and possibly buggy
-  --> $DIR/feature-gate-abi.rs:73:5
+  --> $DIR/feature-gate-abi.rs:73:12
    |
 LL |     extern "platform-intrinsic" fn im2() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/27731
    = help: add `#![feature(platform_intrinsics)]` to the crate attributes to enable
 
 error[E0658]: vectorcall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:75:5
+  --> $DIR/feature-gate-abi.rs:75:12
    |
 LL |     extern "vectorcall" fn im3() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^
    |
    = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
 
 error[E0658]: rust-call ABI is subject to change
-  --> $DIR/feature-gate-abi.rs:76:5
+  --> $DIR/feature-gate-abi.rs:76:12
    |
 LL |     extern "rust-call" fn im4() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/29625
    = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
 
 error[E0658]: msp430-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:77:5
+  --> $DIR/feature-gate-abi.rs:77:12
    |
 LL |     extern "msp430-interrupt" fn im5() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38487
    = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
 
 error[E0658]: PTX ABIs are experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:78:5
+  --> $DIR/feature-gate-abi.rs:78:12
    |
 LL |     extern "ptx-kernel" fn im6() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38788
    = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
 
 error[E0658]: x86-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:79:5
+  --> $DIR/feature-gate-abi.rs:79:12
    |
 LL |     extern "x86-interrupt" fn im7() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/40180
    = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
 
 error[E0658]: thiscall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:80:5
+  --> $DIR/feature-gate-abi.rs:80:12
    |
 LL |     extern "thiscall" fn im8() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^
    |
    = help: add `#![feature(abi_thiscall)]` to the crate attributes to enable
 
 error[E0658]: amdgpu-kernel ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:81:5
+  --> $DIR/feature-gate-abi.rs:81:12
    |
 LL |     extern "amdgpu-kernel" fn im9() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/51575
    = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
 
 error[E0658]: efiapi ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:82:5
+  --> $DIR/feature-gate-abi.rs:82:12
    |
 LL |     extern "efiapi" fn im10() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/65815
    = help: add `#![feature(abi_efiapi)]` to the crate attributes to enable
 
 error[E0658]: intrinsics are subject to change
-  --> $DIR/feature-gate-abi.rs:86:11
+  --> $DIR/feature-gate-abi.rs:86:18
    |
 LL | type A1 = extern "rust-intrinsic" fn();
-   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                  ^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(intrinsics)]` to the crate attributes to enable
 
 error[E0658]: platform intrinsics are experimental and possibly buggy
-  --> $DIR/feature-gate-abi.rs:87:11
+  --> $DIR/feature-gate-abi.rs:87:18
    |
 LL | type A2 = extern "platform-intrinsic" fn();
-   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                  ^^^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/27731
    = help: add `#![feature(platform_intrinsics)]` to the crate attributes to enable
 
 error[E0658]: vectorcall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:88:11
+  --> $DIR/feature-gate-abi.rs:88:18
    |
 LL | type A3 = extern "vectorcall" fn();
-   |           ^^^^^^^^^^^^^^^^^^^^^^^^
+   |                  ^^^^^^^^^^^^
    |
    = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
 
 error[E0658]: rust-call ABI is subject to change
-  --> $DIR/feature-gate-abi.rs:89:11
+  --> $DIR/feature-gate-abi.rs:89:18
    |
 LL | type A4 = extern "rust-call" fn();
-   |           ^^^^^^^^^^^^^^^^^^^^^^^
+   |                  ^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/29625
    = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
 
 error[E0658]: msp430-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:90:11
+  --> $DIR/feature-gate-abi.rs:90:18
    |
 LL | type A5 = extern "msp430-interrupt" fn();
-   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                  ^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38487
    = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
 
 error[E0658]: PTX ABIs are experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:91:11
+  --> $DIR/feature-gate-abi.rs:91:18
    |
 LL | type A6 = extern "ptx-kernel" fn ();
-   |           ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                  ^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38788
    = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
 
 error[E0658]: x86-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:92:11
+  --> $DIR/feature-gate-abi.rs:92:18
    |
 LL | type A7 = extern "x86-interrupt" fn();
-   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                  ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/40180
    = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
 
 error[E0658]: thiscall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:93:11
+  --> $DIR/feature-gate-abi.rs:93:18
    |
 LL | type A8 = extern "thiscall" fn();
-   |           ^^^^^^^^^^^^^^^^^^^^^^
+   |                  ^^^^^^^^^^
    |
    = help: add `#![feature(abi_thiscall)]` to the crate attributes to enable
 
 error[E0658]: amdgpu-kernel ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:94:11
+  --> $DIR/feature-gate-abi.rs:94:18
    |
 LL | type A9 = extern "amdgpu-kernel" fn();
-   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                  ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/51575
    = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
 
 error[E0658]: efiapi ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:95:12
+  --> $DIR/feature-gate-abi.rs:95:19
    |
 LL | type A10 = extern "efiapi" fn();
-   |            ^^^^^^^^^^^^^^^^^^^^
+   |                   ^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/65815
    = help: add `#![feature(abi_efiapi)]` to the crate attributes to enable
 
 error[E0658]: intrinsics are subject to change
-  --> $DIR/feature-gate-abi.rs:98:1
+  --> $DIR/feature-gate-abi.rs:98:8
    |
 LL | extern "rust-intrinsic" {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(intrinsics)]` to the crate attributes to enable
 
 error[E0658]: platform intrinsics are experimental and possibly buggy
-  --> $DIR/feature-gate-abi.rs:99:1
+  --> $DIR/feature-gate-abi.rs:99:8
    |
 LL | extern "platform-intrinsic" {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/27731
    = help: add `#![feature(platform_intrinsics)]` to the crate attributes to enable
 
 error[E0658]: vectorcall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:100:1
+  --> $DIR/feature-gate-abi.rs:100:8
    |
 LL | extern "vectorcall" {}
-   | ^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^
    |
    = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
 
 error[E0658]: rust-call ABI is subject to change
-  --> $DIR/feature-gate-abi.rs:101:1
+  --> $DIR/feature-gate-abi.rs:101:8
    |
 LL | extern "rust-call" {}
-   | ^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/29625
    = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
 
 error[E0658]: msp430-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:102:1
+  --> $DIR/feature-gate-abi.rs:102:8
    |
 LL | extern "msp430-interrupt" {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38487
    = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
 
 error[E0658]: PTX ABIs are experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:103:1
+  --> $DIR/feature-gate-abi.rs:103:8
    |
 LL | extern "ptx-kernel" {}
-   | ^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/38788
    = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
 
 error[E0658]: x86-interrupt ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:104:1
+  --> $DIR/feature-gate-abi.rs:104:8
    |
 LL | extern "x86-interrupt" {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/40180
    = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
 
 error[E0658]: thiscall is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:105:1
+  --> $DIR/feature-gate-abi.rs:105:8
    |
 LL | extern "thiscall" {}
-   | ^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^
    |
    = help: add `#![feature(abi_thiscall)]` to the crate attributes to enable
 
 error[E0658]: amdgpu-kernel ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:106:1
+  --> $DIR/feature-gate-abi.rs:106:8
    |
 LL | extern "amdgpu-kernel" {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/51575
    = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
 
 error[E0658]: efiapi ABI is experimental and subject to change
-  --> $DIR/feature-gate-abi.rs:107:1
+  --> $DIR/feature-gate-abi.rs:107:8
    |
 LL | extern "efiapi" {}
-   | ^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/65815
    = help: add `#![feature(abi_efiapi)]` to the crate attributes to enable
diff --git a/src/test/ui/feature-gates/feature-gate-abi_unadjusted.stderr b/src/test/ui/feature-gates/feature-gate-abi_unadjusted.stderr
index 4954a7d1f71..1757befec35 100644
--- a/src/test/ui/feature-gates/feature-gate-abi_unadjusted.stderr
+++ b/src/test/ui/feature-gates/feature-gate-abi_unadjusted.stderr
@@ -1,10 +1,8 @@
 error[E0658]: unadjusted ABI is an implementation detail and perma-unstable
-  --> $DIR/feature-gate-abi_unadjusted.rs:1:1
+  --> $DIR/feature-gate-abi_unadjusted.rs:1:8
    |
-LL | / extern "unadjusted" fn foo() {
-LL | |
-LL | | }
-   | |_^
+LL | extern "unadjusted" fn foo() {
+   |        ^^^^^^^^^^^^
    |
    = help: add `#![feature(abi_unadjusted)]` to the crate attributes to enable
 
diff --git a/src/test/ui/feature-gates/feature-gate-intrinsics.stderr b/src/test/ui/feature-gates/feature-gate-intrinsics.stderr
index 101a10e8df7..8f943d357ce 100644
--- a/src/test/ui/feature-gates/feature-gate-intrinsics.stderr
+++ b/src/test/ui/feature-gates/feature-gate-intrinsics.stderr
@@ -1,18 +1,16 @@
 error[E0658]: intrinsics are subject to change
-  --> $DIR/feature-gate-intrinsics.rs:1:1
+  --> $DIR/feature-gate-intrinsics.rs:1:8
    |
-LL | / extern "rust-intrinsic" {
-LL | |     fn bar();
-LL | | }
-   | |_^
+LL | extern "rust-intrinsic" {
+   |        ^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(intrinsics)]` to the crate attributes to enable
 
 error[E0658]: intrinsics are subject to change
-  --> $DIR/feature-gate-intrinsics.rs:5:1
+  --> $DIR/feature-gate-intrinsics.rs:5:8
    |
 LL | extern "rust-intrinsic" fn baz() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(intrinsics)]` to the crate attributes to enable
 
diff --git a/src/test/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.stderr b/src/test/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.stderr
index c05379c71ee..657bf13c873 100644
--- a/src/test/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.stderr
+++ b/src/test/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.stderr
@@ -1,35 +1,35 @@
 error[E0658]: rust-call ABI is subject to change
-  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:11:5
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:11:12
    |
 LL |     extern "rust-call" fn call(self, args: ()) -> () {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/29625
    = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
 
 error[E0658]: rust-call ABI is subject to change
-  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:17:5
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:17:12
    |
 LL |     extern "rust-call" fn call_once(self, args: ()) -> () {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/29625
    = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
 
 error[E0658]: rust-call ABI is subject to change
-  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:23:5
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:23:12
    |
 LL |     extern "rust-call" fn call_mut(&self, args: ()) -> () {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/29625
    = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
 
 error[E0658]: rust-call ABI is subject to change
-  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:29:5
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:29:12
    |
 LL |     extern "rust-call" fn call_once(&self, args: ()) -> () {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |            ^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/29625
    = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
diff --git a/src/test/ui/feature-gates/feature-gate-unboxed-closures.stderr b/src/test/ui/feature-gates/feature-gate-unboxed-closures.stderr
index 723c6619887..f343a42eb8f 100644
--- a/src/test/ui/feature-gates/feature-gate-unboxed-closures.stderr
+++ b/src/test/ui/feature-gates/feature-gate-unboxed-closures.stderr
@@ -1,10 +1,8 @@
 error[E0658]: rust-call ABI is subject to change
-  --> $DIR/feature-gate-unboxed-closures.rs:9:5
+  --> $DIR/feature-gate-unboxed-closures.rs:9:12
    |
-LL | /     extern "rust-call" fn call_once(self, (a, b): (u32, u32)) -> u32 {
-LL | |         a + b
-LL | |     }
-   | |_____^
+LL |     extern "rust-call" fn call_once(self, (a, b): (u32, u32)) -> u32 {
+   |            ^^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/29625
    = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
-- 
cgit 1.4.1-3-g733a5


From 1db4d607e7621a7d813743e83125859a47970f79 Mon Sep 17 00:00:00 2001
From: Mazdak Farrokhzad <twingoow@gmail.com>
Date: Mon, 28 Oct 2019 00:29:23 +0100
Subject: parser: allow ABIs from literal macro fragments

---
 src/libsyntax/parse/parser.rs                      | 40 +++++++++++++++-------
 src/libsyntax/parse/parser/expr.rs                 |  6 +++-
 src/libsyntax/parse/parser/item.rs                 |  2 +-
 src/libsyntax/parse/token.rs                       |  7 ----
 src/test/ui/parser/bad-lit-suffixes.rs             |  4 +--
 src/test/ui/parser/bad-lit-suffixes.stderr         |  4 +--
 .../ui/parser/extern-abi-from-mac-literal-frag.rs  | 26 ++++++++++++++
 7 files changed, 63 insertions(+), 26 deletions(-)
 create mode 100644 src/test/ui/parser/extern-abi-from-mac-literal-frag.rs

(limited to 'src/libsyntax/parse/parser/item.rs')

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 382c1a517aa..0c358b1caaf 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -1205,27 +1205,41 @@ impl<'a> Parser<'a> {
         Ok(())
     }
 
-    /// Parses `extern` followed by an optional ABI string, or nothing.
+    /// Parses `extern string_literal?`.
+    /// If `extern` is not found, the Rust ABI is used.
+    /// If `extern` is found and a `string_literal` does not follow, the C ABI is used.
     fn parse_extern_abi(&mut self) -> PResult<'a, Abi> {
         Ok(if self.eat_keyword(kw::Extern) {
-            let ext_sp = self.prev_span;
-            self.parse_opt_abi()?.unwrap_or_else(|| Abi::new(sym::C, ext_sp))
+            self.parse_opt_abi()?
         } else {
             Abi::default()
         })
     }
 
-    /// Parses a string as an ABI spec on an extern type or module.
-    fn parse_opt_abi(&mut self) -> PResult<'a, Option<Abi>> {
-        match self.token.kind {
-            token::Literal(token::Lit { kind: token::Str, symbol, suffix }) |
-            token::Literal(token::Lit { kind: token::StrRaw(..), symbol, suffix }) => {
-                self.expect_no_suffix(self.token.span, "an ABI spec", suffix);
-                self.bump();
-                Ok(Some(Abi::new(symbol, self.prev_span)))
+    /// Parses a string literal as an ABI spec.
+    /// If one is not found, the "C" ABI is used.
+    fn parse_opt_abi(&mut self) -> PResult<'a, Abi> {
+        let span = if self.token.can_begin_literal_or_bool() {
+            let ast::Lit { span, kind, .. } = self.parse_lit()?;
+            match kind {
+                ast::LitKind::Str(symbol, _) => return Ok(Abi::new(symbol, span)),
+                ast::LitKind::Err(_) => {}
+                _ => {
+                    self.struct_span_err(span, "non-string ABI literal")
+                        .span_suggestion(
+                            span,
+                            "specify the ABI with a string literal",
+                            "\"C\"".to_string(),
+                            Applicability::MaybeIncorrect,
+                        )
+                        .emit();
+                }
             }
-            _ => Ok(None),
-        }
+            span
+        } else {
+            self.prev_span
+        };
+        Ok(Abi::new(sym::C, span))
     }
 
     /// We are parsing `async fn`. If we are on Rust 2015, emit an error.
diff --git a/src/libsyntax/parse/parser/expr.rs b/src/libsyntax/parse/parser/expr.rs
index 97b1092452a..80ea8f380fb 100644
--- a/src/libsyntax/parse/parser/expr.rs
+++ b/src/libsyntax/parse/parser/expr.rs
@@ -1116,7 +1116,11 @@ impl<'a> Parser<'a> {
                 Err(self.span_fatal(token.span, &msg))
             }
             Err(err) => {
-                let (lit, span) = (token.expect_lit(), token.span);
+                let span = token.span;
+                let lit = match token.kind {
+                    token::Literal(lit) => lit,
+                    _ => unreachable!(),
+                };
                 self.bump();
                 self.error_literal_from_token(err, lit, span);
                 // Pack possible quotes and prefixes from the original literal into
diff --git a/src/libsyntax/parse/parser/item.rs b/src/libsyntax/parse/parser/item.rs
index 76411e7cf13..ebb1cf12996 100644
--- a/src/libsyntax/parse/parser/item.rs
+++ b/src/libsyntax/parse/parser/item.rs
@@ -110,7 +110,7 @@ impl<'a> Parser<'a> {
                 return Ok(Some(self.parse_item_extern_crate(lo, vis, attrs)?));
             }
 
-            let abi = self.parse_opt_abi()?.unwrap_or_else(|| Abi::new(sym::C, extern_sp));
+            let abi = self.parse_opt_abi()?;
 
             if self.eat_keyword(kw::Fn) {
                 // EXTERN FUNCTION ITEM
diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index ea82aad0eae..6f3da344ccf 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -402,13 +402,6 @@ impl Token {
         }
     }
 
-    crate fn expect_lit(&self) -> Lit {
-        match self.kind {
-            Literal(lit) => lit,
-            _ => panic!("`expect_lit` called on non-literal"),
-        }
-    }
-
     /// Returns `true` if the token is any literal, a minus (which can prefix a literal,
     /// for example a '-42', or one of the boolean idents).
     pub fn can_begin_literal_or_bool(&self) -> bool {
diff --git a/src/test/ui/parser/bad-lit-suffixes.rs b/src/test/ui/parser/bad-lit-suffixes.rs
index 9f301db0995..7db83674efc 100644
--- a/src/test/ui/parser/bad-lit-suffixes.rs
+++ b/src/test/ui/parser/bad-lit-suffixes.rs
@@ -1,9 +1,9 @@
 extern
-    "C"suffix //~ ERROR suffixes on an ABI spec are invalid
+    "C"suffix //~ ERROR suffixes on a string literal are invalid
     fn foo() {}
 
 extern
-    "C"suffix //~ ERROR suffixes on an ABI spec are invalid
+    "C"suffix //~ ERROR suffixes on a string literal are invalid
 {}
 
 fn main() {
diff --git a/src/test/ui/parser/bad-lit-suffixes.stderr b/src/test/ui/parser/bad-lit-suffixes.stderr
index 208fcf43d91..6b0049298ff 100644
--- a/src/test/ui/parser/bad-lit-suffixes.stderr
+++ b/src/test/ui/parser/bad-lit-suffixes.stderr
@@ -1,10 +1,10 @@
-error: suffixes on an ABI spec are invalid
+error: suffixes on a string literal are invalid
   --> $DIR/bad-lit-suffixes.rs:2:5
    |
 LL |     "C"suffix
    |     ^^^^^^^^^ invalid suffix `suffix`
 
-error: suffixes on an ABI spec are invalid
+error: suffixes on a string literal are invalid
   --> $DIR/bad-lit-suffixes.rs:6:5
    |
 LL |     "C"suffix
diff --git a/src/test/ui/parser/extern-abi-from-mac-literal-frag.rs b/src/test/ui/parser/extern-abi-from-mac-literal-frag.rs
new file mode 100644
index 00000000000..cb23f2c808c
--- /dev/null
+++ b/src/test/ui/parser/extern-abi-from-mac-literal-frag.rs
@@ -0,0 +1,26 @@
+// check-pass
+
+// In this test we check that the parser accepts an ABI string when it
+// comes from a macro `literal` fragment as opposed to a hardcoded string.
+
+fn main() {}
+
+macro_rules! abi_from_lit_frag {
+    ($abi:literal) => {
+        extern $abi {
+            fn _import();
+        }
+
+        extern $abi fn _export() {}
+
+        type _PTR = extern $abi fn();
+    }
+}
+
+mod rust {
+    abi_from_lit_frag!("Rust");
+}
+
+mod c {
+    abi_from_lit_frag!("C");
+}
-- 
cgit 1.4.1-3-g733a5


From 3667e6248ec18740ce57db7997333a30c991929b Mon Sep 17 00:00:00 2001
From: Mazdak Farrokhzad <twingoow@gmail.com>
Date: Fri, 11 Oct 2019 13:06:36 +0200
Subject: move PResult to librustc_errors

---
 src/librustc_driver/lib.rs                 |  3 ++-
 src/librustc_errors/lib.rs                 | 10 +++++++++-
 src/librustc_interface/passes.rs           |  3 ++-
 src/libsyntax/attr/mod.rs                  |  3 ++-
 src/libsyntax/parse/lexer/tokentrees.rs    |  3 ++-
 src/libsyntax/parse/mod.rs                 | 11 +----------
 src/libsyntax/parse/parser/attr.rs         |  4 +++-
 src/libsyntax/parse/parser/diagnostics.rs  |  8 +++-----
 src/libsyntax/parse/parser/expr.rs         |  4 ++--
 src/libsyntax/parse/parser/generics.rs     |  4 +++-
 src/libsyntax/parse/parser/item.rs         |  4 ++--
 src/libsyntax/parse/parser/mod.rs          |  4 ++--
 src/libsyntax/parse/parser/module.rs       |  4 +++-
 src/libsyntax/parse/parser/pat.rs          |  4 ++--
 src/libsyntax/parse/parser/path.rs         |  4 ++--
 src/libsyntax/parse/parser/stmt.rs         |  4 ++--
 src/libsyntax/parse/parser/ty.rs           |  4 ++--
 src/libsyntax/tests.rs                     |  4 ++--
 src/libsyntax_expand/expand.rs             |  4 ++--
 src/libsyntax_expand/mbe/macro_parser.rs   |  4 ++--
 src/test/ui-fulldeps/ast_stmt_expr_attr.rs |  3 ++-
 21 files changed, 52 insertions(+), 44 deletions(-)

(limited to 'src/libsyntax/parse/parser/item.rs')

diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index 6e8bc11162f..611b891d99a 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -42,6 +42,7 @@ use rustc::ty::TyCtxt;
 use rustc::util::common::{set_time_depth, time, print_time_passes_entry, ErrorReported};
 use rustc_metadata::locator;
 use rustc_codegen_utils::codegen_backend::CodegenBackend;
+use errors::PResult;
 use rustc_interface::interface;
 use rustc_interface::util::get_codegen_sysroot;
 use rustc_data_structures::sync::SeqCst;
@@ -64,7 +65,7 @@ use std::time::Instant;
 use syntax::ast;
 use syntax::source_map::FileLoader;
 use syntax::feature_gate::{GatedCfg, UnstableFeatures};
-use syntax::parse::{self, PResult};
+use syntax::parse;
 use syntax::symbol::sym;
 use syntax_pos::{DUMMY_SP, FileName};
 
diff --git a/src/librustc_errors/lib.rs b/src/librustc_errors/lib.rs
index 67c180a05e9..fb5cccf61a7 100644
--- a/src/librustc_errors/lib.rs
+++ b/src/librustc_errors/lib.rs
@@ -15,7 +15,8 @@ use Level::*;
 
 use emitter::{Emitter, EmitterWriter, is_case_difference};
 use registry::Registry;
-
+#[cfg(target_arch = "x86_64")]
+use rustc_data_structures::static_assert_size;
 use rustc_data_structures::sync::{self, Lrc, Lock};
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_data_structures::stable_hasher::StableHasher;
@@ -48,6 +49,13 @@ use syntax_pos::{
     SpanSnippetError,
 };
 
+pub type PResult<'a, T> = Result<T, DiagnosticBuilder<'a>>;
+
+// `PResult` is used a lot. Make sure it doesn't unintentionally get bigger.
+// (See also the comment on `DiagnosticBuilderInner`.)
+#[cfg(target_arch = "x86_64")]
+static_assert_size!(PResult<'_, bool>, 16);
+
 /// Indicates the confidence in the correctness of a suggestion.
 ///
 /// All suggestions are marked with an `Applicability`. Tools use the applicability of a suggestion
diff --git a/src/librustc_interface/passes.rs b/src/librustc_interface/passes.rs
index 52332744d1a..ce34caee6fa 100644
--- a/src/librustc_interface/passes.rs
+++ b/src/librustc_interface/passes.rs
@@ -22,6 +22,7 @@ use rustc_codegen_utils::codegen_backend::CodegenBackend;
 use rustc_codegen_utils::link::filename_for_metadata;
 use rustc_data_structures::{box_region_allow_access, declare_box_region_type, parallel};
 use rustc_data_structures::sync::{Lrc, ParallelIterator, par_iter};
+use rustc_errors::PResult;
 use rustc_incremental;
 use rustc_metadata::cstore;
 use rustc_mir as mir;
@@ -36,7 +37,7 @@ use syntax::{self, ast, visit};
 use syntax::early_buffered_lints::BufferedEarlyLint;
 use syntax_expand::base::{NamedSyntaxExtension, ExtCtxt};
 use syntax::mut_visit::MutVisitor;
-use syntax::parse::{self, PResult};
+use syntax::parse;
 use syntax::util::node_count::NodeCounter;
 use syntax::symbol::Symbol;
 use syntax_pos::FileName;
diff --git a/src/libsyntax/attr/mod.rs b/src/libsyntax/attr/mod.rs
index 1534d2723c8..d609225a54f 100644
--- a/src/libsyntax/attr/mod.rs
+++ b/src/libsyntax/attr/mod.rs
@@ -16,7 +16,6 @@ use crate::mut_visit::visit_clobber;
 use crate::source_map::{BytePos, Spanned};
 use crate::parse::lexer::comments::doc_comment_style;
 use crate::parse;
-use crate::parse::PResult;
 use crate::token::{self, Token};
 use crate::ptr::P;
 use crate::sess::ParseSess;
@@ -25,6 +24,8 @@ use crate::ThinVec;
 use crate::tokenstream::{DelimSpan, TokenStream, TokenTree, TreeAndJoint};
 use crate::GLOBALS;
 
+use errors::PResult;
+
 use log::debug;
 use syntax_pos::Span;
 
diff --git a/src/libsyntax/parse/lexer/tokentrees.rs b/src/libsyntax/parse/lexer/tokentrees.rs
index 3c15a5e1dae..2b056434d4d 100644
--- a/src/libsyntax/parse/lexer/tokentrees.rs
+++ b/src/libsyntax/parse/lexer/tokentrees.rs
@@ -4,10 +4,11 @@ use syntax_pos::Span;
 use super::{StringReader, UnmatchedBrace};
 
 use crate::print::pprust::token_to_string;
-use crate::parse::PResult;
 use crate::token::{self, Token};
 use crate::tokenstream::{DelimSpan, IsJoint::{self, *}, TokenStream, TokenTree, TreeAndJoint};
 
+use errors::PResult;
+
 impl<'a> StringReader<'a> {
     crate fn into_token_trees(self) -> (PResult<'a, TokenStream>, Vec<UnmatchedBrace>) {
         let mut tt_reader = TokenTreesReader {
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index 7db0ca0b78d..badf8bcba57 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -7,9 +7,7 @@ use crate::tokenstream::{self, TokenStream, TokenTree};
 use crate::print::pprust;
 use crate::sess::ParseSess;
 
-use errors::{FatalError, Level, Diagnostic, DiagnosticBuilder};
-#[cfg(target_arch = "x86_64")]
-use rustc_data_structures::static_assert_size;
+use errors::{PResult, FatalError, Level, Diagnostic};
 use rustc_data_structures::sync::Lrc;
 use syntax_pos::{Span, SourceFile, FileName};
 
@@ -29,13 +27,6 @@ pub mod lexer;
 crate mod classify;
 crate mod literal;
 
-pub type PResult<'a, T> = Result<T, DiagnosticBuilder<'a>>;
-
-// `PResult` is used a lot. Make sure it doesn't unintentionally get bigger.
-// (See also the comment on `DiagnosticBuilderInner`.)
-#[cfg(target_arch = "x86_64")]
-static_assert_size!(PResult<'_, bool>, 16);
-
 #[derive(Clone)]
 pub struct Directory<'a> {
     pub path: Cow<'a, Path>,
diff --git a/src/libsyntax/parse/parser/attr.rs b/src/libsyntax/parse/parser/attr.rs
index aa0542a09a9..2f1b87da7e9 100644
--- a/src/libsyntax/parse/parser/attr.rs
+++ b/src/libsyntax/parse/parser/attr.rs
@@ -1,10 +1,12 @@
-use super::{SeqSep, PResult, Parser, TokenType, PathStyle};
+use super::{SeqSep, Parser, TokenType, PathStyle};
 use crate::attr;
 use crate::ast;
 use crate::token::{self, Nonterminal, DelimToken};
 use crate::tokenstream::{TokenStream, TokenTree};
 use crate::source_map::Span;
 
+use errors::PResult;
+
 use log::debug;
 
 #[derive(Debug)]
diff --git a/src/libsyntax/parse/parser/diagnostics.rs b/src/libsyntax/parse/parser/diagnostics.rs
index 09f0b9b74b2..26d7f48025e 100644
--- a/src/libsyntax/parse/parser/diagnostics.rs
+++ b/src/libsyntax/parse/parser/diagnostics.rs
@@ -1,7 +1,4 @@
-use super::{
-    BlockMode, PathStyle, SemiColonMode, TokenType, TokenExpectType,
-    SeqSep, PResult, Parser
-};
+use super::{BlockMode, PathStyle, SemiColonMode, TokenType, TokenExpectType, SeqSep, Parser};
 use crate::ast::{
     self, Param, BinOpKind, BindingMode, BlockCheckMode, Expr, ExprKind, Ident, Item, ItemKind,
     Mutability, Pat, PatKind, PathSegment, QSelf, Ty, TyKind,
@@ -12,7 +9,8 @@ use crate::ptr::P;
 use crate::symbol::{kw, sym};
 use crate::ThinVec;
 use crate::util::parser::AssocOp;
-use errors::{Applicability, DiagnosticBuilder, DiagnosticId, pluralize};
+
+use errors::{PResult, Applicability, DiagnosticBuilder, DiagnosticId, pluralize};
 use rustc_data_structures::fx::FxHashSet;
 use syntax_pos::{Span, DUMMY_SP, MultiSpan, SpanSnippetError};
 use log::{debug, trace};
diff --git a/src/libsyntax/parse/parser/expr.rs b/src/libsyntax/parse/parser/expr.rs
index 4b962201e85..9faa4aefbb6 100644
--- a/src/libsyntax/parse/parser/expr.rs
+++ b/src/libsyntax/parse/parser/expr.rs
@@ -1,4 +1,4 @@
-use super::{Parser, PResult, Restrictions, PrevTokenKind, TokenType, PathStyle, BlockMode};
+use super::{Parser, Restrictions, PrevTokenKind, TokenType, PathStyle, BlockMode};
 use super::{SemiColonMode, SeqSep, TokenExpectType};
 use super::pat::{GateOr, PARAM_EXPECTED};
 use super::diagnostics::Error;
@@ -18,7 +18,7 @@ use crate::ptr::P;
 use crate::source_map::{self, Span};
 use crate::util::parser::{AssocOp, Fixity, prec_let_scrutinee_needs_par};
 
-use errors::Applicability;
+use errors::{PResult, Applicability};
 use syntax_pos::symbol::{kw, sym};
 use syntax_pos::Symbol;
 use std::mem;
diff --git a/src/libsyntax/parse/parser/generics.rs b/src/libsyntax/parse/parser/generics.rs
index cfc3768cac5..ae9ecd8fe39 100644
--- a/src/libsyntax/parse/parser/generics.rs
+++ b/src/libsyntax/parse/parser/generics.rs
@@ -1,4 +1,4 @@
-use super::{Parser, PResult};
+use super::Parser;
 
 use crate::ast::{self, WhereClause, GenericParam, GenericParamKind, GenericBounds, Attribute};
 use crate::token;
@@ -6,6 +6,8 @@ use crate::source_map::DUMMY_SP;
 
 use syntax_pos::symbol::{kw, sym};
 
+use errors::PResult;
+
 impl<'a> Parser<'a> {
     /// Parses bounds of a lifetime parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
     ///
diff --git a/src/libsyntax/parse/parser/item.rs b/src/libsyntax/parse/parser/item.rs
index 9d543055f23..3c618d75d34 100644
--- a/src/libsyntax/parse/parser/item.rs
+++ b/src/libsyntax/parse/parser/item.rs
@@ -1,4 +1,4 @@
-use super::{Parser, PResult, PathStyle};
+use super::{Parser, PathStyle};
 use super::diagnostics::{Error, dummy_arg, ConsumeClosingDelim};
 
 use crate::maybe_whole;
@@ -17,7 +17,7 @@ use crate::ThinVec;
 
 use log::debug;
 use std::mem;
-use errors::{Applicability, DiagnosticBuilder, DiagnosticId, StashKey};
+use errors::{PResult, Applicability, DiagnosticBuilder, DiagnosticId, StashKey};
 use syntax_pos::BytePos;
 
 /// Whether the type alias or associated type is a concrete type or an opaque type.
diff --git a/src/libsyntax/parse/parser/mod.rs b/src/libsyntax/parse/parser/mod.rs
index 6498b674a3b..f7f7b0e83d4 100644
--- a/src/libsyntax/parse/parser/mod.rs
+++ b/src/libsyntax/parse/parser/mod.rs
@@ -15,7 +15,7 @@ use crate::ast::{
     self, Abi, DUMMY_NODE_ID, AttrStyle, Attribute, CrateSugar, Ident,
     IsAsync, MacDelimiter, Mutability, StrStyle, Visibility, VisibilityKind, Unsafety,
 };
-use crate::parse::{PResult, Directory, DirectoryOwnership};
+use crate::parse::{Directory, DirectoryOwnership};
 use crate::parse::lexer::UnmatchedBrace;
 use crate::parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
 use crate::token::{self, Token, TokenKind, DelimToken};
@@ -27,7 +27,7 @@ use crate::symbol::{kw, sym, Symbol};
 use crate::tokenstream::{self, DelimSpan, TokenTree, TokenStream, TreeAndJoint};
 use crate::ThinVec;
 
-use errors::{Applicability, DiagnosticBuilder, DiagnosticId, FatalError};
+use errors::{PResult, Applicability, DiagnosticBuilder, DiagnosticId, FatalError};
 use syntax_pos::{Span, BytePos, DUMMY_SP, FileName};
 use log::debug;
 
diff --git a/src/libsyntax/parse/parser/module.rs b/src/libsyntax/parse/parser/module.rs
index 70e0dfc3e88..72049daaed3 100644
--- a/src/libsyntax/parse/parser/module.rs
+++ b/src/libsyntax/parse/parser/module.rs
@@ -1,4 +1,4 @@
-use super::{Parser, PResult};
+use super::Parser;
 use super::item::ItemInfo;
 use super::diagnostics::Error;
 
@@ -9,6 +9,8 @@ use crate::token::{self, TokenKind};
 use crate::source_map::{SourceMap, Span, DUMMY_SP, FileName};
 use crate::symbol::sym;
 
+use errors::PResult;
+
 use std::path::{self, Path, PathBuf};
 
 /// Information about the path to a module.
diff --git a/src/libsyntax/parse/parser/pat.rs b/src/libsyntax/parse/parser/pat.rs
index c4a983188fa..f347300da71 100644
--- a/src/libsyntax/parse/parser/pat.rs
+++ b/src/libsyntax/parse/parser/pat.rs
@@ -1,4 +1,4 @@
-use super::{Parser, PResult, PathStyle};
+use super::{Parser, PathStyle};
 
 use crate::{maybe_recover_from_interpolated_ty_qpath, maybe_whole};
 use crate::ptr::P;
@@ -10,7 +10,7 @@ use crate::print::pprust;
 use crate::source_map::{respan, Span, Spanned};
 use crate::ThinVec;
 use syntax_pos::symbol::{kw, sym};
-use errors::{Applicability, DiagnosticBuilder};
+use errors::{PResult, Applicability, DiagnosticBuilder};
 
 type Expected = Option<&'static str>;
 
diff --git a/src/libsyntax/parse/parser/path.rs b/src/libsyntax/parse/parser/path.rs
index 2659e0c680e..9ceb3ba1eb4 100644
--- a/src/libsyntax/parse/parser/path.rs
+++ b/src/libsyntax/parse/parser/path.rs
@@ -1,4 +1,4 @@
-use super::{Parser, PResult, TokenType};
+use super::{Parser, TokenType};
 
 use crate::{maybe_whole, ThinVec};
 use crate::ast::{self, QSelf, Path, PathSegment, Ident, ParenthesizedArgs, AngleBracketedArgs};
@@ -9,7 +9,7 @@ use syntax_pos::symbol::{kw, sym};
 
 use std::mem;
 use log::debug;
-use errors::{Applicability, pluralize};
+use errors::{PResult, Applicability, pluralize};
 
 /// Specifies how to parse a path.
 #[derive(Copy, Clone, PartialEq)]
diff --git a/src/libsyntax/parse/parser/stmt.rs b/src/libsyntax/parse/parser/stmt.rs
index 010fd9c37fd..2a3d6b05bb9 100644
--- a/src/libsyntax/parse/parser/stmt.rs
+++ b/src/libsyntax/parse/parser/stmt.rs
@@ -1,4 +1,4 @@
-use super::{Parser, PResult, Restrictions, PrevTokenKind, SemiColonMode, BlockMode};
+use super::{Parser, Restrictions, PrevTokenKind, SemiColonMode, BlockMode};
 use super::expr::LhsExpr;
 use super::path::PathStyle;
 use super::pat::GateOr;
@@ -14,7 +14,7 @@ use crate::source_map::{respan, Span};
 use crate::symbol::{kw, sym};
 
 use std::mem;
-use errors::Applicability;
+use errors::{PResult, Applicability};
 
 impl<'a> Parser<'a> {
     /// Parses a statement. This stops just before trailing semicolons on everything but items.
diff --git a/src/libsyntax/parse/parser/ty.rs b/src/libsyntax/parse/parser/ty.rs
index 4183416e628..a891634e611 100644
--- a/src/libsyntax/parse/parser/ty.rs
+++ b/src/libsyntax/parse/parser/ty.rs
@@ -1,4 +1,4 @@
-use super::{Parser, PResult, PathStyle, PrevTokenKind, TokenType};
+use super::{Parser, PathStyle, PrevTokenKind, TokenType};
 use super::item::ParamCfg;
 
 use crate::{maybe_whole, maybe_recover_from_interpolated_ty_qpath};
@@ -10,7 +10,7 @@ use crate::token::{self, Token};
 use crate::source_map::Span;
 use crate::symbol::{kw};
 
-use errors::{Applicability, pluralize};
+use errors::{PResult, Applicability, pluralize};
 
 /// Returns `true` if `IDENT t` can start a type -- `IDENT::a::b`, `IDENT<u8, u8>`,
 /// `IDENT<<u8 as Trait>::AssocTy>`.
diff --git a/src/libsyntax/tests.rs b/src/libsyntax/tests.rs
index e73c8b43bcc..ed457c3627f 100644
--- a/src/libsyntax/tests.rs
+++ b/src/libsyntax/tests.rs
@@ -1,5 +1,5 @@
 use crate::ast;
-use crate::parse::{PResult, source_file_to_stream};
+use crate::parse::source_file_to_stream;
 use crate::parse::new_parser_from_source_str;
 use crate::parse::parser::Parser;
 use crate::sess::ParseSess;
@@ -8,7 +8,7 @@ use crate::tokenstream::TokenStream;
 use crate::with_default_globals;
 
 use errors::emitter::EmitterWriter;
-use errors::Handler;
+use errors::{PResult, Handler};
 use rustc_data_structures::sync::Lrc;
 use syntax_pos::{BytePos, Span, MultiSpan};
 
diff --git a/src/libsyntax_expand/expand.rs b/src/libsyntax_expand/expand.rs
index 6d1f0abe49e..e91dd2aba15 100644
--- a/src/libsyntax_expand/expand.rs
+++ b/src/libsyntax_expand/expand.rs
@@ -12,7 +12,7 @@ use syntax::configure;
 use syntax::config::StripUnconfigured;
 use syntax::feature_gate::{self, Features, GateIssue, is_builtin_attr, emit_feature_err};
 use syntax::mut_visit::*;
-use syntax::parse::{DirectoryOwnership, PResult};
+use syntax::parse::DirectoryOwnership;
 use syntax::parse::parser::Parser;
 use syntax::print::pprust;
 use syntax::ptr::P;
@@ -23,7 +23,7 @@ use syntax::tokenstream::{TokenStream, TokenTree};
 use syntax::visit::{self, Visitor};
 use syntax::util::map_in_place::MapInPlace;
 
-use errors::{Applicability, FatalError};
+use errors::{PResult, Applicability, FatalError};
 use smallvec::{smallvec, SmallVec};
 use syntax_pos::{Span, DUMMY_SP, FileName};
 
diff --git a/src/libsyntax_expand/mbe/macro_parser.rs b/src/libsyntax_expand/mbe/macro_parser.rs
index 950e7c0f286..80bf27e1a94 100644
--- a/src/libsyntax_expand/mbe/macro_parser.rs
+++ b/src/libsyntax_expand/mbe/macro_parser.rs
@@ -77,7 +77,7 @@ use TokenTreeOrTokenTreeSlice::*;
 use crate::mbe::{self, TokenTree};
 
 use syntax::ast::{Ident, Name};
-use syntax::parse::{Directory, PResult};
+use syntax::parse::Directory;
 use syntax::parse::parser::{Parser, PathStyle};
 use syntax::print::pprust;
 use syntax::sess::ParseSess;
@@ -85,7 +85,7 @@ use syntax::symbol::{kw, sym, Symbol};
 use syntax::token::{self, DocComment, Nonterminal, Token};
 use syntax::tokenstream::{DelimSpan, TokenStream};
 
-use errors::FatalError;
+use errors::{PResult, FatalError};
 use smallvec::{smallvec, SmallVec};
 use syntax_pos::Span;
 
diff --git a/src/test/ui-fulldeps/ast_stmt_expr_attr.rs b/src/test/ui-fulldeps/ast_stmt_expr_attr.rs
index 6277e2e7ea9..ac864e76784 100644
--- a/src/test/ui-fulldeps/ast_stmt_expr_attr.rs
+++ b/src/test/ui-fulldeps/ast_stmt_expr_attr.rs
@@ -6,14 +6,15 @@
 #![feature(rustc_private)]
 
 extern crate syntax;
+extern crate rustc_errors;
 
+use rustc_errors::PResult;
 use syntax::ast::*;
 use syntax::attr::*;
 use syntax::ast;
 use syntax::sess::ParseSess;
 use syntax::source_map::{FilePathMapping, FileName};
 use syntax::parse;
-use syntax::parse::PResult;
 use syntax::parse::new_parser_from_source_str;
 use syntax::parse::parser::Parser;
 use syntax::token;
-- 
cgit 1.4.1-3-g733a5


From 2cd48e8a3b71256d7db1ac61e8994c06620238b6 Mon Sep 17 00:00:00 2001
From: Mazdak Farrokhzad <twingoow@gmail.com>
Date: Thu, 7 Nov 2019 13:11:59 +0100
Subject: ast::MethodSig -> ast::FnSig

---
 src/librustc/hir/lowering/item.rs          |  2 +-
 src/librustc/hir/map/def_collector.rs      |  2 +-
 src/librustc_interface/util.rs             |  4 ++--
 src/librustc_save_analysis/dump_visitor.rs |  2 +-
 src/librustc_save_analysis/sig.rs          |  4 ++--
 src/libsyntax/ast.rs                       | 10 +++++-----
 src/libsyntax/mut_visit.rs                 |  2 +-
 src/libsyntax/parse/parser/item.rs         |  6 +++---
 src/libsyntax/print/pprust.rs              |  2 +-
 src/libsyntax/visit.rs                     |  2 +-
 src/libsyntax_ext/deriving/generic/mod.rs  |  2 +-
 11 files changed, 19 insertions(+), 19 deletions(-)

(limited to 'src/libsyntax/parse/parser/item.rs')

diff --git a/src/librustc/hir/lowering/item.rs b/src/librustc/hir/lowering/item.rs
index a01f59eea0b..861130f0c69 100644
--- a/src/librustc/hir/lowering/item.rs
+++ b/src/librustc/hir/lowering/item.rs
@@ -1255,7 +1255,7 @@ impl LoweringContext<'_> {
     fn lower_method_sig(
         &mut self,
         generics: &Generics,
-        sig: &MethodSig,
+        sig: &FnSig,
         fn_def_id: DefId,
         impl_trait_return_allow: bool,
         is_async: Option<NodeId>,
diff --git a/src/librustc/hir/map/def_collector.rs b/src/librustc/hir/map/def_collector.rs
index 57c1421bde6..d705737cc93 100644
--- a/src/librustc/hir/map/def_collector.rs
+++ b/src/librustc/hir/map/def_collector.rs
@@ -228,7 +228,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
 
     fn visit_impl_item(&mut self, ii: &'a ImplItem) {
         let def_data = match ii.kind {
-            ImplItemKind::Method(MethodSig {
+            ImplItemKind::Method(FnSig {
                 ref header,
                 ref decl,
             }, ref body) if header.asyncness.node.is_async() => {
diff --git a/src/librustc_interface/util.rs b/src/librustc_interface/util.rs
index d0c15073f16..cd7af3be9b5 100644
--- a/src/librustc_interface/util.rs
+++ b/src/librustc_interface/util.rs
@@ -802,7 +802,7 @@ impl<'a> MutVisitor for ReplaceBodyWithLoop<'a> {
     fn flat_map_trait_item(&mut self, i: ast::TraitItem) -> SmallVec<[ast::TraitItem; 1]> {
         let is_const = match i.kind {
             ast::TraitItemKind::Const(..) => true,
-            ast::TraitItemKind::Method(ast::MethodSig { ref decl, ref header, .. }, _) =>
+            ast::TraitItemKind::Method(ast::FnSig { ref decl, ref header, .. }, _) =>
                 header.constness.node == ast::Constness::Const || Self::should_ignore_fn(decl),
             _ => false,
         };
@@ -812,7 +812,7 @@ impl<'a> MutVisitor for ReplaceBodyWithLoop<'a> {
     fn flat_map_impl_item(&mut self, i: ast::ImplItem) -> SmallVec<[ast::ImplItem; 1]> {
         let is_const = match i.kind {
             ast::ImplItemKind::Const(..) => true,
-            ast::ImplItemKind::Method(ast::MethodSig { ref decl, ref header, .. }, _) =>
+            ast::ImplItemKind::Method(ast::FnSig { ref decl, ref header, .. }, _) =>
                 header.constness.node == ast::Constness::Const || Self::should_ignore_fn(decl),
             _ => false,
         };
diff --git a/src/librustc_save_analysis/dump_visitor.rs b/src/librustc_save_analysis/dump_visitor.rs
index 5c5fbcc07de..883d8964564 100644
--- a/src/librustc_save_analysis/dump_visitor.rs
+++ b/src/librustc_save_analysis/dump_visitor.rs
@@ -272,7 +272,7 @@ impl<'l, 'tcx> DumpVisitor<'l, 'tcx> {
 
     fn process_method(
         &mut self,
-        sig: &'l ast::MethodSig,
+        sig: &'l ast::FnSig,
         body: Option<&'l ast::Block>,
         id: ast::NodeId,
         ident: ast::Ident,
diff --git a/src/librustc_save_analysis/sig.rs b/src/librustc_save_analysis/sig.rs
index 019e92717b5..887aeb03b89 100644
--- a/src/librustc_save_analysis/sig.rs
+++ b/src/librustc_save_analysis/sig.rs
@@ -72,7 +72,7 @@ pub fn method_signature(
     id: NodeId,
     ident: ast::Ident,
     generics: &ast::Generics,
-    m: &ast::MethodSig,
+    m: &ast::FnSig,
     scx: &SaveContext<'_, '_>,
 ) -> Option<Signature> {
     if !scx.config.signatures {
@@ -932,7 +932,7 @@ fn make_method_signature(
     id: NodeId,
     ident: ast::Ident,
     generics: &ast::Generics,
-    m: &ast::MethodSig,
+    m: &ast::FnSig,
     scx: &SaveContext<'_, '_>,
 ) -> Result {
     // FIXME code dup with function signature
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 18151a1586c..86a353cdfd2 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -1501,10 +1501,10 @@ pub struct MutTy {
     pub mutbl: Mutability,
 }
 
-/// Represents a method's signature in a trait declaration,
-/// or in an implementation.
+/// Represents a function's signature in a trait declaration,
+/// trait implementation, or free function.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
-pub struct MethodSig {
+pub struct FnSig {
     pub header: FnHeader,
     pub decl: P<FnDecl>,
 }
@@ -1528,7 +1528,7 @@ pub struct TraitItem {
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub enum TraitItemKind {
     Const(P<Ty>, Option<P<Expr>>),
-    Method(MethodSig, Option<P<Block>>),
+    Method(FnSig, Option<P<Block>>),
     Type(GenericBounds, Option<P<Ty>>),
     Macro(Mac),
 }
@@ -1552,7 +1552,7 @@ pub struct ImplItem {
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub enum ImplItemKind {
     Const(P<Ty>, P<Expr>),
-    Method(MethodSig, P<Block>),
+    Method(FnSig, P<Block>),
     TyAlias(P<Ty>),
     OpaqueTy(GenericBounds),
     Macro(Mac),
diff --git a/src/libsyntax/mut_visit.rs b/src/libsyntax/mut_visit.rs
index 0c90652526d..f2ad7dea73b 100644
--- a/src/libsyntax/mut_visit.rs
+++ b/src/libsyntax/mut_visit.rs
@@ -357,7 +357,7 @@ pub fn visit_bounds<T: MutVisitor>(bounds: &mut GenericBounds, vis: &mut T) {
 }
 
 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
-pub fn visit_method_sig<T: MutVisitor>(MethodSig { header, decl }: &mut MethodSig, vis: &mut T) {
+pub fn visit_method_sig<T: MutVisitor>(FnSig { header, decl }: &mut FnSig, vis: &mut T) {
     vis.visit_fn_header(header);
     vis.visit_fn_decl(decl);
 }
diff --git a/src/libsyntax/parse/parser/item.rs b/src/libsyntax/parse/parser/item.rs
index 3c618d75d34..500e70ae8e5 100644
--- a/src/libsyntax/parse/parser/item.rs
+++ b/src/libsyntax/parse/parser/item.rs
@@ -8,7 +8,7 @@ use crate::ast::{ItemKind, ImplItem, ImplItemKind, TraitItem, TraitItemKind, Use
 use crate::ast::{PathSegment, IsAuto, Constness, IsAsync, Unsafety, Defaultness};
 use crate::ast::{Visibility, VisibilityKind, Mutability, FnHeader, ForeignItem, ForeignItemKind};
 use crate::ast::{Ty, TyKind, Generics, GenericBounds, TraitRef, EnumDef, VariantData, StructField};
-use crate::ast::{Mac, MacDelimiter, Block, BindingMode, FnDecl, MethodSig, SelfKind, Param};
+use crate::ast::{Mac, MacDelimiter, Block, BindingMode, FnDecl, FnSig, SelfKind, Param};
 use crate::parse::token;
 use crate::tokenstream::{TokenTree, TokenStream};
 use crate::symbol::{kw, sym};
@@ -1897,14 +1897,14 @@ impl<'a> Parser<'a> {
     fn parse_method_sig(
         &mut self,
         is_name_required: fn(&token::Token) -> bool,
-    ) -> PResult<'a, (Ident, MethodSig, Generics)> {
+    ) -> PResult<'a, (Ident, FnSig, Generics)> {
         let header = self.parse_fn_front_matter()?;
         let (ident, decl, generics) = self.parse_fn_sig(ParamCfg {
             is_self_allowed: true,
             allow_c_variadic: false,
             is_name_required,
         })?;
-        Ok((ident, MethodSig { header, decl }, generics))
+        Ok((ident, FnSig { header, decl }, generics))
     }
 
     /// Parses all the "front matter" for a `fn` declaration, up to
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 4ca4bdeb046..e7335a00cb0 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -1541,7 +1541,7 @@ impl<'a> State<'a> {
     crate fn print_method_sig(&mut self,
                             ident: ast::Ident,
                             generics: &ast::Generics,
-                            m: &ast::MethodSig,
+                            m: &ast::FnSig,
                             vis: &ast::Visibility)
                             {
         self.print_fn(&m.decl,
diff --git a/src/libsyntax/visit.rs b/src/libsyntax/visit.rs
index cfd160fd577..e2983db4318 100644
--- a/src/libsyntax/visit.rs
+++ b/src/libsyntax/visit.rs
@@ -25,7 +25,7 @@ pub enum FnKind<'a> {
     ItemFn(Ident, &'a FnHeader, &'a Visibility, &'a Block),
 
     /// E.g., `fn foo(&self)`.
-    Method(Ident, &'a MethodSig, Option<&'a Visibility>, &'a Block),
+    Method(Ident, &'a FnSig, Option<&'a Visibility>, &'a Block),
 
     /// E.g., `|x, y| body`.
     Closure(&'a Expr),
diff --git a/src/libsyntax_ext/deriving/generic/mod.rs b/src/libsyntax_ext/deriving/generic/mod.rs
index b18fd50ae76..b24306def74 100644
--- a/src/libsyntax_ext/deriving/generic/mod.rs
+++ b/src/libsyntax_ext/deriving/generic/mod.rs
@@ -950,7 +950,7 @@ impl<'a> MethodDef<'a> {
 
         let trait_lo_sp = trait_.span.shrink_to_lo();
 
-        let sig = ast::MethodSig {
+        let sig = ast::FnSig {
             header: ast::FnHeader {
                 unsafety,
                 abi: Abi::new(abi, trait_lo_sp),
-- 
cgit 1.4.1-3-g733a5


From b4c6abcf9e6c1d2710e7ad6a9ce44b3ca6b10d52 Mon Sep 17 00:00:00 2001
From: Mazdak Farrokhzad <twingoow@gmail.com>
Date: Thu, 7 Nov 2019 13:33:37 +0100
Subject: ast::ItemKind::Fn: use ast::FnSig

---
 src/librustc/hir/lowering/item.rs          |  2 +-
 src/librustc/hir/map/def_collector.rs      | 13 ++++---------
 src/librustc_interface/util.rs             | 13 +++++++------
 src/librustc_passes/ast_validation.rs      |  8 ++++----
 src/librustc_resolve/late.rs               |  2 +-
 src/librustc_save_analysis/dump_visitor.rs |  4 ++--
 src/librustc_save_analysis/lib.rs          |  4 ++--
 src/librustc_save_analysis/sig.rs          |  2 +-
 src/libsyntax/ast.rs                       |  2 +-
 src/libsyntax/mut_visit.rs                 | 11 +++++------
 src/libsyntax/parse/parser/item.rs         |  2 +-
 src/libsyntax/print/pprust.rs              |  6 +++---
 src/libsyntax/visit.rs                     |  9 ++++-----
 src/libsyntax_ext/global_allocator.rs      | 15 +++++----------
 src/libsyntax_ext/test.rs                  | 14 +++++++-------
 src/libsyntax_ext/test_harness.rs          |  7 +++----
 16 files changed, 51 insertions(+), 63 deletions(-)

(limited to 'src/libsyntax/parse/parser/item.rs')

diff --git a/src/librustc/hir/lowering/item.rs b/src/librustc/hir/lowering/item.rs
index 861130f0c69..7aa1aa8bb51 100644
--- a/src/librustc/hir/lowering/item.rs
+++ b/src/librustc/hir/lowering/item.rs
@@ -306,7 +306,7 @@ impl LoweringContext<'_> {
                     self.lower_const_body(e)
                 )
             }
-            ItemKind::Fn(ref decl, header, ref generics, ref body) => {
+            ItemKind::Fn(FnSig { ref decl, header }, ref generics, ref body) => {
                 let fn_def_id = self.resolver.definitions().local_def_id(id);
                 self.with_new_scopes(|this| {
                     this.current_item = Some(ident.span);
diff --git a/src/librustc/hir/map/def_collector.rs b/src/librustc/hir/map/def_collector.rs
index d705737cc93..d858e00a2e9 100644
--- a/src/librustc/hir/map/def_collector.rs
+++ b/src/librustc/hir/map/def_collector.rs
@@ -100,7 +100,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
 
         // Pick the def data. This need not be unique, but the more
         // information we encapsulate into, the better
-        let def_data = match i.kind {
+        let def_data = match &i.kind {
             ItemKind::Impl(..) => DefPathData::Impl,
             ItemKind::Mod(..) if i.ident.name == kw::Invalid => {
                 return visit::walk_item(self, i);
@@ -109,19 +109,14 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) |
             ItemKind::OpaqueTy(..) | ItemKind::ExternCrate(..) | ItemKind::ForeignMod(..) |
             ItemKind::TyAlias(..) => DefPathData::TypeNs(i.ident.name),
-            ItemKind::Fn(
-                ref decl,
-                ref header,
-                ref generics,
-                ref body,
-            ) if header.asyncness.node.is_async() => {
+            ItemKind::Fn(sig, generics, body) if sig.header.asyncness.node.is_async() => {
                 return self.visit_async_fn(
                     i.id,
                     i.ident.name,
                     i.span,
-                    header,
+                    &sig.header,
                     generics,
-                    decl,
+                    &sig.decl,
                     body,
                 )
             }
diff --git a/src/librustc_interface/util.rs b/src/librustc_interface/util.rs
index cd7af3be9b5..a74ea4bca39 100644
--- a/src/librustc_interface/util.rs
+++ b/src/librustc_interface/util.rs
@@ -786,14 +786,17 @@ impl<'a> ReplaceBodyWithLoop<'a> {
             false
         }
     }
+
+    fn is_sig_const(sig: &ast::FnSig) -> bool {
+        sig.header.constness.node == ast::Constness::Const || Self::should_ignore_fn(&sig.decl)
+    }
 }
 
 impl<'a> MutVisitor for ReplaceBodyWithLoop<'a> {
     fn visit_item_kind(&mut self, i: &mut ast::ItemKind) {
         let is_const = match i {
             ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => true,
-            ast::ItemKind::Fn(ref decl, ref header, _, _) =>
-                header.constness.node == ast::Constness::Const || Self::should_ignore_fn(decl),
+            ast::ItemKind::Fn(ref sig, _, _) => Self::is_sig_const(sig),
             _ => false,
         };
         self.run(is_const, |s| noop_visit_item_kind(i, s))
@@ -802,8 +805,7 @@ impl<'a> MutVisitor for ReplaceBodyWithLoop<'a> {
     fn flat_map_trait_item(&mut self, i: ast::TraitItem) -> SmallVec<[ast::TraitItem; 1]> {
         let is_const = match i.kind {
             ast::TraitItemKind::Const(..) => true,
-            ast::TraitItemKind::Method(ast::FnSig { ref decl, ref header, .. }, _) =>
-                header.constness.node == ast::Constness::Const || Self::should_ignore_fn(decl),
+            ast::TraitItemKind::Method(ref sig, _) => Self::is_sig_const(sig),
             _ => false,
         };
         self.run(is_const, |s| noop_flat_map_trait_item(i, s))
@@ -812,8 +814,7 @@ impl<'a> MutVisitor for ReplaceBodyWithLoop<'a> {
     fn flat_map_impl_item(&mut self, i: ast::ImplItem) -> SmallVec<[ast::ImplItem; 1]> {
         let is_const = match i.kind {
             ast::ImplItemKind::Const(..) => true,
-            ast::ImplItemKind::Method(ast::FnSig { ref decl, ref header, .. }, _) =>
-                header.constness.node == ast::Constness::Const || Self::should_ignore_fn(decl),
+            ast::ImplItemKind::Method(ref sig, _) => Self::is_sig_const(sig),
             _ => false,
         };
         self.run(is_const, |s| noop_flat_map_impl_item(i, s))
diff --git a/src/librustc_passes/ast_validation.rs b/src/librustc_passes/ast_validation.rs
index d1a801b3006..6151fc58d89 100644
--- a/src/librustc_passes/ast_validation.rs
+++ b/src/librustc_passes/ast_validation.rs
@@ -575,12 +575,12 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                         .note("only trait implementations may be annotated with default").emit();
                 }
             }
-            ItemKind::Fn(ref decl, ref header, ref generics, _) => {
-                self.visit_fn_header(header);
-                self.check_fn_decl(decl);
+            ItemKind::Fn(ref sig, ref generics, _) => {
+                self.visit_fn_header(&sig.header);
+                self.check_fn_decl(&sig.decl);
                 // We currently do not permit const generics in `const fn`, as
                 // this is tantamount to allowing compile-time dependent typing.
-                if header.constness.node == Constness::Const {
+                if sig.header.constness.node == Constness::Const {
                     // Look for const generics and error if we find any.
                     for param in &generics.params {
                         match param.kind {
diff --git a/src/librustc_resolve/late.rs b/src/librustc_resolve/late.rs
index 58af4b817d2..a23684ea649 100644
--- a/src/librustc_resolve/late.rs
+++ b/src/librustc_resolve/late.rs
@@ -731,7 +731,7 @@ impl<'a, 'b> LateResolutionVisitor<'a, '_> {
         match item.kind {
             ItemKind::TyAlias(_, ref generics) |
             ItemKind::OpaqueTy(_, ref generics) |
-            ItemKind::Fn(_, _, ref generics, _) => {
+            ItemKind::Fn(_, ref generics, _) => {
                 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes),
                                             |this| visit::walk_item(this, item));
             }
diff --git a/src/librustc_save_analysis/dump_visitor.rs b/src/librustc_save_analysis/dump_visitor.rs
index 883d8964564..92c391fb4a3 100644
--- a/src/librustc_save_analysis/dump_visitor.rs
+++ b/src/librustc_save_analysis/dump_visitor.rs
@@ -1334,8 +1334,8 @@ impl<'l, 'tcx> Visitor<'l> for DumpVisitor<'l, 'tcx> {
                     );
                 }
             }
-            Fn(ref decl, ref header, ref ty_params, ref body) => {
-                self.process_fn(item, &decl, &header, ty_params, &body)
+            Fn(ref sig, ref ty_params, ref body) => {
+                self.process_fn(item, &sig.decl, &sig.header, ty_params, &body)
             }
             Static(ref typ, _, ref expr) => self.process_static_or_const_item(item, typ, expr),
             Const(ref typ, ref expr) => self.process_static_or_const_item(item, &typ, &expr),
diff --git a/src/librustc_save_analysis/lib.rs b/src/librustc_save_analysis/lib.rs
index a2f8837c581..424d57c8fe7 100644
--- a/src/librustc_save_analysis/lib.rs
+++ b/src/librustc_save_analysis/lib.rs
@@ -180,7 +180,7 @@ impl<'l, 'tcx> SaveContext<'l, 'tcx> {
 
     pub fn get_item_data(&self, item: &ast::Item) -> Option<Data> {
         match item.kind {
-            ast::ItemKind::Fn(ref decl, .., ref generics, _) => {
+            ast::ItemKind::Fn(ref sig, .., ref generics, _) => {
                 let qualname = format!("::{}",
                     self.tcx.def_path_str(self.tcx.hir().local_def_id_from_node_id(item.id)));
                 filter!(self.span_utils, item.ident.span);
@@ -190,7 +190,7 @@ impl<'l, 'tcx> SaveContext<'l, 'tcx> {
                     span: self.span_from_span(item.ident.span),
                     name: item.ident.to_string(),
                     qualname,
-                    value: make_signature(decl, generics),
+                    value: make_signature(&sig.decl, generics),
                     parent: None,
                     children: vec![],
                     decl_id: None,
diff --git a/src/librustc_save_analysis/sig.rs b/src/librustc_save_analysis/sig.rs
index 887aeb03b89..d1b9b8ff44d 100644
--- a/src/librustc_save_analysis/sig.rs
+++ b/src/librustc_save_analysis/sig.rs
@@ -376,7 +376,7 @@ impl Sig for ast::Item {
 
                 Ok(extend_sig(ty, text, defs, vec![]))
             }
-            ast::ItemKind::Fn(ref decl, header, ref generics, _) => {
+            ast::ItemKind::Fn(ast::FnSig { ref decl, header }, ref generics, _) => {
                 let mut text = String::new();
                 if header.constness.node == ast::Constness::Const {
                     text.push_str("const ");
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 86a353cdfd2..b57d2238991 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -2433,7 +2433,7 @@ pub enum ItemKind {
     /// A function declaration (`fn`).
     ///
     /// E.g., `fn foo(bar: usize) -> usize { .. }`.
-    Fn(P<FnDecl>, FnHeader, Generics, P<Block>),
+    Fn(FnSig, Generics, P<Block>),
     /// A module declaration (`mod`).
     ///
     /// E.g., `mod foo;` or `mod foo { .. }`.
diff --git a/src/libsyntax/mut_visit.rs b/src/libsyntax/mut_visit.rs
index f2ad7dea73b..7696ea48f93 100644
--- a/src/libsyntax/mut_visit.rs
+++ b/src/libsyntax/mut_visit.rs
@@ -357,7 +357,7 @@ pub fn visit_bounds<T: MutVisitor>(bounds: &mut GenericBounds, vis: &mut T) {
 }
 
 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
-pub fn visit_method_sig<T: MutVisitor>(FnSig { header, decl }: &mut FnSig, vis: &mut T) {
+pub fn visit_fn_sig<T: MutVisitor>(FnSig { header, decl }: &mut FnSig, vis: &mut T) {
     vis.visit_fn_header(header);
     vis.visit_fn_decl(decl);
 }
@@ -878,9 +878,8 @@ pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
             vis.visit_ty(ty);
             vis.visit_expr(expr);
         }
-        ItemKind::Fn(decl, header, generics, body) => {
-            vis.visit_fn_decl(decl);
-            vis.visit_fn_header(header);
+        ItemKind::Fn(sig, generics, body) => {
+            visit_fn_sig(sig, vis);
             vis.visit_generics(generics);
             vis.visit_block(body);
         }
@@ -938,7 +937,7 @@ pub fn noop_flat_map_trait_item<T: MutVisitor>(mut item: TraitItem, vis: &mut T)
             visit_opt(default, |default| vis.visit_expr(default));
         }
         TraitItemKind::Method(sig, body) => {
-            visit_method_sig(sig, vis);
+            visit_fn_sig(sig, vis);
             visit_opt(body, |body| vis.visit_block(body));
         }
         TraitItemKind::Type(bounds, default) => {
@@ -970,7 +969,7 @@ pub fn noop_flat_map_impl_item<T: MutVisitor>(mut item: ImplItem, visitor: &mut
             visitor.visit_expr(expr);
         }
         ImplItemKind::Method(sig, body) => {
-            visit_method_sig(sig, visitor);
+            visit_fn_sig(sig, visitor);
             visitor.visit_block(body);
         }
         ImplItemKind::TyAlias(ty) => visitor.visit_ty(ty),
diff --git a/src/libsyntax/parse/parser/item.rs b/src/libsyntax/parse/parser/item.rs
index 500e70ae8e5..531ad532a54 100644
--- a/src/libsyntax/parse/parser/item.rs
+++ b/src/libsyntax/parse/parser/item.rs
@@ -1800,7 +1800,7 @@ impl<'a> Parser<'a> {
             is_name_required: |_| true,
         })?;
         let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
-        let kind = ItemKind::Fn(decl, header, generics, body);
+        let kind = ItemKind::Fn(FnSig { decl, header }, generics, body);
         self.mk_item_with_info(attrs, lo, vis, (ident, kind, Some(inner_attrs)))
     }
 
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index e7335a00cb0..2203e8d9d06 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -1199,11 +1199,11 @@ impl<'a> State<'a> {
                 self.s.word(";");
                 self.end(); // end the outer cbox
             }
-            ast::ItemKind::Fn(ref decl, header, ref param_names, ref body) => {
+            ast::ItemKind::Fn(ref sig, ref param_names, ref body) => {
                 self.head("");
                 self.print_fn(
-                    decl,
-                    header,
+                    &sig.decl,
+                    sig.header,
                     Some(item.ident),
                     param_names,
                     &item.vis
diff --git a/src/libsyntax/visit.rs b/src/libsyntax/visit.rs
index e2983db4318..ea2dc357e6e 100644
--- a/src/libsyntax/visit.rs
+++ b/src/libsyntax/visit.rs
@@ -244,12 +244,11 @@ pub fn walk_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a Item) {
             visitor.visit_ty(typ);
             visitor.visit_expr(expr);
         }
-        ItemKind::Fn(ref declaration, ref header, ref generics, ref body) => {
+        ItemKind::Fn(ref sig, ref generics, ref body) => {
             visitor.visit_generics(generics);
-            visitor.visit_fn_header(header);
-            visitor.visit_fn(FnKind::ItemFn(item.ident, header,
-                                            &item.vis, body),
-                             declaration,
+            visitor.visit_fn_header(&sig.header);
+            visitor.visit_fn(FnKind::ItemFn(item.ident, &sig.header, &item.vis, body),
+                             &sig.decl,
                              item.span,
                              item.id)
         }
diff --git a/src/libsyntax_ext/global_allocator.rs b/src/libsyntax_ext/global_allocator.rs
index 90d2ea38bc3..dc29e057455 100644
--- a/src/libsyntax_ext/global_allocator.rs
+++ b/src/libsyntax_ext/global_allocator.rs
@@ -1,7 +1,7 @@
 use crate::util::check_builtin_macro_attribute;
 
 use syntax::ast::{ItemKind, Mutability, Stmt, Ty, TyKind, Unsafety};
-use syntax::ast::{self, Param, Attribute, Expr, FnHeader, Generics, Ident};
+use syntax::ast::{self, Param, Attribute, Expr, FnSig, FnHeader, Generics, Ident};
 use syntax::expand::allocator::{AllocatorKind, AllocatorMethod, AllocatorTy, ALLOCATOR_METHODS};
 use syntax::ptr::P;
 use syntax::symbol::{kw, sym, Symbol};
@@ -73,15 +73,10 @@ impl AllocFnFactory<'_, '_> {
             .collect();
         let result = self.call_allocator(method.name, args);
         let (output_ty, output_expr) = self.ret_ty(&method.output, result);
-        let kind = ItemKind::Fn(
-            self.cx.fn_decl(abi_args, ast::FunctionRetTy::Ty(output_ty)),
-            FnHeader {
-                unsafety: Unsafety::Unsafe,
-                ..FnHeader::default()
-            },
-            Generics::default(),
-            self.cx.block_expr(output_expr),
-        );
+        let decl = self.cx.fn_decl(abi_args, ast::FunctionRetTy::Ty(output_ty));
+        let header = FnHeader { unsafety: Unsafety::Unsafe, ..FnHeader::default() };
+        let sig = FnSig { decl, header };
+        let kind = ItemKind::Fn(sig, Generics::default(), self.cx.block_expr(output_expr));
         let item = self.cx.item(
             self.span,
             self.cx.ident_of(&self.kind.fn_name(method.name), self.span),
diff --git a/src/libsyntax_ext/test.rs b/src/libsyntax_ext/test.rs
index b0da413d63a..8656100c921 100644
--- a/src/libsyntax_ext/test.rs
+++ b/src/libsyntax_ext/test.rs
@@ -310,15 +310,15 @@ fn test_type(cx: &ExtCtxt<'_>) -> TestType {
 fn has_test_signature(cx: &ExtCtxt<'_>, i: &ast::Item) -> bool {
     let has_should_panic_attr = attr::contains_name(&i.attrs, sym::should_panic);
     let ref sd = cx.parse_sess.span_diagnostic;
-    if let ast::ItemKind::Fn(ref decl, ref header, ref generics, _) = i.kind {
-        if header.unsafety == ast::Unsafety::Unsafe {
+    if let ast::ItemKind::Fn(ref sig, ref generics, _) = i.kind {
+        if sig.header.unsafety == ast::Unsafety::Unsafe {
             sd.span_err(
                 i.span,
                 "unsafe functions cannot be used for tests"
             );
             return false
         }
-        if header.asyncness.node.is_async() {
+        if sig.header.asyncness.node.is_async() {
             sd.span_err(
                 i.span,
                 "async functions cannot be used for tests"
@@ -329,13 +329,13 @@ fn has_test_signature(cx: &ExtCtxt<'_>, i: &ast::Item) -> bool {
 
         // If the termination trait is active, the compiler will check that the output
         // type implements the `Termination` trait as `libtest` enforces that.
-        let has_output = match decl.output {
+        let has_output = match sig.decl.output {
             ast::FunctionRetTy::Default(..) => false,
             ast::FunctionRetTy::Ty(ref t) if t.kind.is_unit() => false,
             _ => true
         };
 
-        if !decl.inputs.is_empty() {
+        if !sig.decl.inputs.is_empty() {
             sd.span_err(i.span, "functions used as tests can not have any arguments");
             return false;
         }
@@ -361,10 +361,10 @@ fn has_test_signature(cx: &ExtCtxt<'_>, i: &ast::Item) -> bool {
 }
 
 fn has_bench_signature(cx: &ExtCtxt<'_>, i: &ast::Item) -> bool {
-    let has_sig = if let ast::ItemKind::Fn(ref decl, _, _, _) = i.kind {
+    let has_sig = if let ast::ItemKind::Fn(ref sig, _, _) = i.kind {
         // N.B., inadequate check, but we're running
         // well before resolve, can't get too deep.
-        decl.inputs.len() == 1
+        sig.decl.inputs.len() == 1
     } else {
         false
     };
diff --git a/src/libsyntax_ext/test_harness.rs b/src/libsyntax_ext/test_harness.rs
index 33d41a7f53e..1492f6f575f 100644
--- a/src/libsyntax_ext/test_harness.rs
+++ b/src/libsyntax_ext/test_harness.rs
@@ -306,10 +306,9 @@ fn mk_main(cx: &mut TestCtxt<'_>) -> P<ast::Item> {
         ecx.block(sp, vec![call_test_main])
     };
 
-    let main = ast::ItemKind::Fn(ecx.fn_decl(vec![], ast::FunctionRetTy::Ty(main_ret_ty)),
-                           ast::FnHeader::default(),
-                           ast::Generics::default(),
-                           main_body);
+    let decl = ecx.fn_decl(vec![], ast::FunctionRetTy::Ty(main_ret_ty));
+    let sig = ast::FnSig { decl, header: ast::FnHeader::default() };
+    let main = ast::ItemKind::Fn(sig, ast::Generics::default(), main_body);
 
     // Honor the reexport_test_harness_main attribute
     let main_id = match cx.reexport_test_harness_main {
-- 
cgit 1.4.1-3-g733a5


From 4ae2728fa8052915414127dce28245eb8f70842a Mon Sep 17 00:00:00 2001
From: Mazdak Farrokhzad <twingoow@gmail.com>
Date: Tue, 15 Oct 2019 22:48:13 +0200
Subject: move syntax::parse -> librustc_parse

also move MACRO_ARGUMENTS -> librustc_parse
---
 Cargo.lock                                         |   26 +-
 src/librustc_driver/Cargo.toml                     |    1 +
 src/librustc_driver/lib.rs                         |   17 +-
 src/librustc_interface/Cargo.toml                  |    1 +
 src/librustc_interface/interface.rs                |    2 +-
 src/librustc_interface/passes.rs                   |   15 +-
 src/librustc_interface/util.rs                     |    1 +
 src/librustc_lexer/src/lib.rs                      |    2 +-
 src/librustc_metadata/Cargo.toml                   |    1 +
 src/librustc_metadata/rmeta/decoder/cstore_impl.rs |    4 +-
 src/librustc_parse/Cargo.toml                      |   21 +
 src/librustc_parse/error_codes.rs                  |  174 ++
 src/librustc_parse/lexer/mod.rs                    |  643 ++++++
 src/librustc_parse/lexer/tokentrees.rs             |  280 +++
 .../lexer/unescape_error_reporting.rs              |  215 ++
 src/librustc_parse/lexer/unicode_chars.rs          |  392 ++++
 src/librustc_parse/lib.rs                          |  423 ++++
 src/librustc_parse/parser/attr.rs                  |  351 +++
 src/librustc_parse/parser/diagnostics.rs           | 1549 ++++++++++++++
 src/librustc_parse/parser/expr.rs                  | 1963 +++++++++++++++++
 src/librustc_parse/parser/generics.rs              |  308 +++
 src/librustc_parse/parser/item.rs                  | 2238 ++++++++++++++++++++
 src/librustc_parse/parser/mod.rs                   | 1393 ++++++++++++
 src/librustc_parse/parser/module.rs                |  316 +++
 src/librustc_parse/parser/pat.rs                   | 1015 +++++++++
 src/librustc_parse/parser/path.rs                  |  497 +++++
 src/librustc_parse/parser/stmt.rs                  |  482 +++++
 src/librustc_parse/parser/ty.rs                    |  460 ++++
 src/librustc_parse/validate_attr.rs                |  111 +
 src/librustc_passes/Cargo.toml                     |    5 +-
 src/librustc_passes/ast_validation.rs              |    4 +-
 src/librustc_save_analysis/Cargo.toml              |    1 +
 src/librustc_save_analysis/span_utils.rs           |    6 +-
 src/librustdoc/html/highlight.rs                   |    4 +-
 src/librustdoc/lib.rs                              |    1 +
 src/librustdoc/passes/check_code_block_syntax.rs   |    2 +-
 src/librustdoc/test.rs                             |    5 +-
 src/libsyntax/ast.rs                               |    6 +-
 src/libsyntax/attr/builtin.rs                      |    6 +-
 src/libsyntax/attr/mod.rs                          |    2 +-
 src/libsyntax/error_codes.rs                       |  165 --
 src/libsyntax/lib.rs                               |    7 +-
 src/libsyntax/parse/lexer/mod.rs                   |  643 ------
 src/libsyntax/parse/lexer/tokentrees.rs            |  280 ---
 .../parse/lexer/unescape_error_reporting.rs        |  215 --
 src/libsyntax/parse/lexer/unicode_chars.rs         |  392 ----
 src/libsyntax/parse/mod.rs                         |  420 ----
 src/libsyntax/parse/parser/attr.rs                 |  358 ----
 src/libsyntax/parse/parser/diagnostics.rs          | 1547 --------------
 src/libsyntax/parse/parser/expr.rs                 | 1964 -----------------
 src/libsyntax/parse/parser/generics.rs             |  309 ---
 src/libsyntax/parse/parser/item.rs                 | 2237 -------------------
 src/libsyntax/parse/parser/mod.rs                  | 1391 ------------
 src/libsyntax/parse/parser/module.rs               |  315 ---
 src/libsyntax/parse/parser/pat.rs                  | 1016 ---------
 src/libsyntax/parse/parser/path.rs                 |  497 -----
 src/libsyntax/parse/parser/stmt.rs                 |  480 -----
 src/libsyntax/parse/parser/ty.rs                   |  458 ----
 src/libsyntax/parse/validate_attr.rs               |  112 -
 src/libsyntax/print/pprust.rs                      |   14 +-
 src/libsyntax/sess.rs                              |    4 +-
 src/libsyntax/token.rs                             |   44 +-
 src/libsyntax/util/comments.rs                     |    4 +-
 src/libsyntax/util/literal.rs                      |   10 +-
 src/libsyntax/util/parser.rs                       |    4 +-
 src/libsyntax_expand/Cargo.toml                    |    5 +-
 src/libsyntax_expand/base.rs                       |    8 +-
 src/libsyntax_expand/config.rs                     |    6 +-
 src/libsyntax_expand/expand.rs                     |    6 +-
 src/libsyntax_expand/mbe/macro_parser.rs           |    6 +-
 src/libsyntax_expand/mbe/macro_rules.rs            |   10 +-
 src/libsyntax_expand/parse/lexer/tests.rs          |    4 +-
 src/libsyntax_expand/parse/tests.rs                |    2 +-
 src/libsyntax_expand/proc_macro.rs                 |    9 +-
 src/libsyntax_expand/proc_macro_server.rs          |   10 +-
 src/libsyntax_expand/tests.rs                      |    2 +-
 src/libsyntax_ext/Cargo.toml                       |    1 +
 src/libsyntax_ext/assert.rs                        |    4 +-
 src/libsyntax_ext/cmdline_attrs.rs                 |    3 +-
 src/libsyntax_ext/source_util.rs                   |   10 +-
 src/libsyntax_ext/util.rs                          |    2 +-
 src/test/ui-fulldeps/ast_stmt_expr_attr.rs         |    7 +-
 src/test/ui-fulldeps/mod_dir_path_canonicalized.rs |    3 +-
 src/test/ui-fulldeps/pprust-expr-roundtrip.rs      |    3 +-
 84 files changed, 12993 insertions(+), 12937 deletions(-)
 create mode 100644 src/librustc_parse/Cargo.toml
 create mode 100644 src/librustc_parse/error_codes.rs
 create mode 100644 src/librustc_parse/lexer/mod.rs
 create mode 100644 src/librustc_parse/lexer/tokentrees.rs
 create mode 100644 src/librustc_parse/lexer/unescape_error_reporting.rs
 create mode 100644 src/librustc_parse/lexer/unicode_chars.rs
 create mode 100644 src/librustc_parse/lib.rs
 create mode 100644 src/librustc_parse/parser/attr.rs
 create mode 100644 src/librustc_parse/parser/diagnostics.rs
 create mode 100644 src/librustc_parse/parser/expr.rs
 create mode 100644 src/librustc_parse/parser/generics.rs
 create mode 100644 src/librustc_parse/parser/item.rs
 create mode 100644 src/librustc_parse/parser/mod.rs
 create mode 100644 src/librustc_parse/parser/module.rs
 create mode 100644 src/librustc_parse/parser/pat.rs
 create mode 100644 src/librustc_parse/parser/path.rs
 create mode 100644 src/librustc_parse/parser/stmt.rs
 create mode 100644 src/librustc_parse/parser/ty.rs
 create mode 100644 src/librustc_parse/validate_attr.rs
 delete mode 100644 src/libsyntax/parse/lexer/mod.rs
 delete mode 100644 src/libsyntax/parse/lexer/tokentrees.rs
 delete mode 100644 src/libsyntax/parse/lexer/unescape_error_reporting.rs
 delete mode 100644 src/libsyntax/parse/lexer/unicode_chars.rs
 delete mode 100644 src/libsyntax/parse/mod.rs
 delete mode 100644 src/libsyntax/parse/parser/attr.rs
 delete mode 100644 src/libsyntax/parse/parser/diagnostics.rs
 delete mode 100644 src/libsyntax/parse/parser/expr.rs
 delete mode 100644 src/libsyntax/parse/parser/generics.rs
 delete mode 100644 src/libsyntax/parse/parser/item.rs
 delete mode 100644 src/libsyntax/parse/parser/mod.rs
 delete mode 100644 src/libsyntax/parse/parser/module.rs
 delete mode 100644 src/libsyntax/parse/parser/pat.rs
 delete mode 100644 src/libsyntax/parse/parser/path.rs
 delete mode 100644 src/libsyntax/parse/parser/stmt.rs
 delete mode 100644 src/libsyntax/parse/parser/ty.rs
 delete mode 100644 src/libsyntax/parse/validate_attr.rs

(limited to 'src/libsyntax/parse/parser/item.rs')

diff --git a/Cargo.lock b/Cargo.lock
index 0f770f3eadb..7e51f96cfb8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3504,6 +3504,7 @@ dependencies = [
  "rustc_lint",
  "rustc_metadata",
  "rustc_mir",
+ "rustc_parse",
  "rustc_plugin",
  "rustc_plugin_impl",
  "rustc_save_analysis",
@@ -3571,6 +3572,7 @@ dependencies = [
  "rustc_lint",
  "rustc_metadata",
  "rustc_mir",
+ "rustc_parse",
  "rustc_passes",
  "rustc_plugin_impl",
  "rustc_privacy",
@@ -3648,6 +3650,7 @@ dependencies = [
  "rustc_data_structures",
  "rustc_errors",
  "rustc_index",
+ "rustc_parse",
  "rustc_target",
  "serialize",
  "smallvec 1.0.0",
@@ -3691,6 +3694,21 @@ dependencies = [
  "core",
 ]
 
+[[package]]
+name = "rustc_parse"
+version = "0.0.0"
+dependencies = [
+ "bitflags",
+ "log",
+ "rustc_data_structures",
+ "rustc_errors",
+ "rustc_lexer",
+ "rustc_target",
+ "smallvec 1.0.0",
+ "syntax",
+ "syntax_pos",
+]
+
 [[package]]
 name = "rustc_passes"
 version = "0.0.0"
@@ -3700,6 +3718,7 @@ dependencies = [
  "rustc_data_structures",
  "rustc_errors",
  "rustc_index",
+ "rustc_parse",
  "rustc_target",
  "syntax",
  "syntax_pos",
@@ -3762,6 +3781,7 @@ dependencies = [
  "rustc",
  "rustc_codegen_utils",
  "rustc_data_structures",
+ "rustc_parse",
  "serde_json",
  "syntax",
  "syntax_pos",
@@ -4371,14 +4391,11 @@ dependencies = [
 name = "syntax_expand"
 version = "0.0.0"
 dependencies = [
- "bitflags",
- "lazy_static 1.3.0",
  "log",
  "rustc_data_structures",
  "rustc_errors",
- "rustc_index",
  "rustc_lexer",
- "scoped-tls",
+ "rustc_parse",
  "serialize",
  "smallvec 1.0.0",
  "syntax",
@@ -4393,6 +4410,7 @@ dependencies = [
  "log",
  "rustc_data_structures",
  "rustc_errors",
+ "rustc_parse",
  "rustc_target",
  "smallvec 1.0.0",
  "syntax",
diff --git a/src/librustc_driver/Cargo.toml b/src/librustc_driver/Cargo.toml
index a9e4e6db1c7..19726d6aff2 100644
--- a/src/librustc_driver/Cargo.toml
+++ b/src/librustc_driver/Cargo.toml
@@ -21,6 +21,7 @@ rustc_data_structures = { path = "../librustc_data_structures" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
 rustc_metadata = { path = "../librustc_metadata" }
 rustc_mir = { path = "../librustc_mir" }
+rustc_parse = { path = "../librustc_parse" }
 rustc_plugin = { path = "../librustc_plugin/deprecated" } # To get this in the sysroot
 rustc_plugin_impl = { path = "../librustc_plugin" }
 rustc_save_analysis = { path = "../librustc_save_analysis" }
diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index 611b891d99a..380cbed4b21 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -65,7 +65,6 @@ use std::time::Instant;
 use syntax::ast;
 use syntax::source_map::FileLoader;
 use syntax::feature_gate::{GatedCfg, UnstableFeatures};
-use syntax::parse;
 use syntax::symbol::sym;
 use syntax_pos::{DUMMY_SP, FileName};
 
@@ -1096,14 +1095,16 @@ pub fn handle_options(args: &[String]) -> Option<getopts::Matches> {
 }
 
 fn parse_crate_attrs<'a>(sess: &'a Session, input: &Input) -> PResult<'a, Vec<ast::Attribute>> {
-    match *input {
-        Input::File(ref ifile) => {
-            parse::parse_crate_attrs_from_file(ifile, &sess.parse_sess)
+    match input {
+        Input::File(ifile) => {
+            rustc_parse::parse_crate_attrs_from_file(ifile, &sess.parse_sess)
         }
-        Input::Str { ref name, ref input } => {
-            parse::parse_crate_attrs_from_source_str(name.clone(),
-                                                     input.clone(),
-                                                     &sess.parse_sess)
+        Input::Str { name, input } => {
+            rustc_parse::parse_crate_attrs_from_source_str(
+                name.clone(),
+                input.clone(),
+                &sess.parse_sess,
+            )
         }
     }
 }
diff --git a/src/librustc_interface/Cargo.toml b/src/librustc_interface/Cargo.toml
index 35b93db1d65..de59882bbdf 100644
--- a/src/librustc_interface/Cargo.toml
+++ b/src/librustc_interface/Cargo.toml
@@ -16,6 +16,7 @@ smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 syntax = { path = "../libsyntax" }
 syntax_ext = { path = "../libsyntax_ext" }
 syntax_expand = { path = "../libsyntax_expand" }
+rustc_parse = { path = "../librustc_parse" }
 syntax_pos = { path = "../libsyntax_pos" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 rustc = { path = "../librustc" }
diff --git a/src/librustc_interface/interface.rs b/src/librustc_interface/interface.rs
index 61f30392e06..02068b2ce38 100644
--- a/src/librustc_interface/interface.rs
+++ b/src/librustc_interface/interface.rs
@@ -11,11 +11,11 @@ use rustc_codegen_utils::codegen_backend::CodegenBackend;
 use rustc_data_structures::OnDrop;
 use rustc_data_structures::sync::Lrc;
 use rustc_data_structures::fx::{FxHashSet, FxHashMap};
+use rustc_parse::new_parser_from_source_str;
 use std::path::PathBuf;
 use std::result;
 use std::sync::{Arc, Mutex};
 use syntax::ast::{self, MetaItemKind};
-use syntax::parse::new_parser_from_source_str;
 use syntax::token;
 use syntax::source_map::{FileName, FileLoader, SourceMap};
 use syntax::sess::ParseSess;
diff --git a/src/librustc_interface/passes.rs b/src/librustc_interface/passes.rs
index c874e94124d..0e38de9a0ed 100644
--- a/src/librustc_interface/passes.rs
+++ b/src/librustc_interface/passes.rs
@@ -26,6 +26,7 @@ use rustc_errors::PResult;
 use rustc_incremental;
 use rustc_metadata::cstore;
 use rustc_mir as mir;
+use rustc_parse::{parse_crate_from_file, parse_crate_from_source_str};
 use rustc_passes::{self, ast_validation, hir_stats, layout_test};
 use rustc_plugin as plugin;
 use rustc_plugin::registry::Registry;
@@ -37,7 +38,6 @@ use syntax::{self, ast, visit};
 use syntax::early_buffered_lints::BufferedEarlyLint;
 use syntax_expand::base::{NamedSyntaxExtension, ExtCtxt};
 use syntax::mut_visit::MutVisitor;
-use syntax::parse;
 use syntax::util::node_count::NodeCounter;
 use syntax::symbol::Symbol;
 use syntax_pos::FileName;
@@ -60,12 +60,11 @@ pub fn parse<'a>(sess: &'a Session, input: &Input) -> PResult<'a, ast::Crate> {
     let krate = time(sess, "parsing", || {
         let _prof_timer = sess.prof.generic_activity("parse_crate");
 
-        match *input {
-            Input::File(ref file) => parse::parse_crate_from_file(file, &sess.parse_sess),
-            Input::Str {
-                ref input,
-                ref name,
-            } => parse::parse_crate_from_source_str(name.clone(), input.clone(), &sess.parse_sess),
+        match input {
+            Input::File(file) => parse_crate_from_file(file, &sess.parse_sess),
+            Input::Str { input, name } => {
+                parse_crate_from_source_str(name.clone(), input.clone(), &sess.parse_sess)
+            }
         }
     })?;
 
@@ -484,7 +483,7 @@ pub fn lower_to_hir(
 ) -> Result<hir::map::Forest> {
     // Lower AST to HIR.
     let hir_forest = time(sess, "lowering AST -> HIR", || {
-        let nt_to_tokenstream = syntax::parse::nt_to_tokenstream;
+        let nt_to_tokenstream = rustc_parse::nt_to_tokenstream;
         let hir_crate = lower_crate(sess, &dep_graph, &krate, resolver, nt_to_tokenstream);
 
         if sess.opts.debugging_opts.hir_stats {
diff --git a/src/librustc_interface/util.rs b/src/librustc_interface/util.rs
index c02e5b9ae28..1cdb0ac87c5 100644
--- a/src/librustc_interface/util.rs
+++ b/src/librustc_interface/util.rs
@@ -50,6 +50,7 @@ pub fn diagnostics_registry() -> Registry {
     // FIXME: need to figure out a way to get these back in here
     // all_errors.extend_from_slice(get_codegen_backend(sess).diagnostics());
     all_errors.extend_from_slice(&rustc_metadata::error_codes::DIAGNOSTICS);
+    all_errors.extend_from_slice(&rustc_parse::error_codes::DIAGNOSTICS);
     all_errors.extend_from_slice(&rustc_passes::error_codes::DIAGNOSTICS);
     all_errors.extend_from_slice(&rustc_plugin::error_codes::DIAGNOSTICS);
     all_errors.extend_from_slice(&rustc_mir::error_codes::DIAGNOSTICS);
diff --git a/src/librustc_lexer/src/lib.rs b/src/librustc_lexer/src/lib.rs
index c50808adec1..3cecb4317b1 100644
--- a/src/librustc_lexer/src/lib.rs
+++ b/src/librustc_lexer/src/lib.rs
@@ -1,7 +1,7 @@
 //! Low-level Rust lexer.
 //!
 //! Tokens produced by this lexer are not yet ready for parsing the Rust syntax,
-//! for that see `libsyntax::parse::lexer`, which converts this basic token stream
+//! for that see `librustc_parse::lexer`, which converts this basic token stream
 //! into wide tokens used by actual parser.
 //!
 //! The purpose of this crate is to convert raw sources into a labeled sequence
diff --git a/src/librustc_metadata/Cargo.toml b/src/librustc_metadata/Cargo.toml
index 5bc047e001b..b1431563f21 100644
--- a/src/librustc_metadata/Cargo.toml
+++ b/src/librustc_metadata/Cargo.toml
@@ -23,4 +23,5 @@ rustc_serialize = { path = "../libserialize", package = "serialize" }
 stable_deref_trait = "1.0.0"
 syntax = { path = "../libsyntax" }
 syntax_expand = { path = "../libsyntax_expand" }
+rustc_parse = { path = "../librustc_parse" }
 syntax_pos = { path = "../libsyntax_pos" }
diff --git a/src/librustc_metadata/rmeta/decoder/cstore_impl.rs b/src/librustc_metadata/rmeta/decoder/cstore_impl.rs
index 6eacfc28de2..19cfdeac57e 100644
--- a/src/librustc_metadata/rmeta/decoder/cstore_impl.rs
+++ b/src/librustc_metadata/rmeta/decoder/cstore_impl.rs
@@ -18,6 +18,8 @@ use rustc::hir::map::{DefKey, DefPath, DefPathHash};
 use rustc::hir::map::definitions::DefPathTable;
 use rustc::util::nodemap::DefIdMap;
 use rustc_data_structures::svh::Svh;
+use rustc_parse::source_file_to_stream;
+use rustc_parse::parser::emit_unclosed_delims;
 
 use smallvec::SmallVec;
 use std::any::Any;
@@ -27,8 +29,6 @@ use std::sync::Arc;
 use syntax::ast;
 use syntax::attr;
 use syntax::source_map;
-use syntax::parse::source_file_to_stream;
-use syntax::parse::parser::emit_unclosed_delims;
 use syntax::source_map::Spanned;
 use syntax::symbol::Symbol;
 use syntax_pos::{Span, FileName};
diff --git a/src/librustc_parse/Cargo.toml b/src/librustc_parse/Cargo.toml
new file mode 100644
index 00000000000..4579f9d472d
--- /dev/null
+++ b/src/librustc_parse/Cargo.toml
@@ -0,0 +1,21 @@
+[package]
+authors = ["The Rust Project Developers"]
+name = "rustc_parse"
+version = "0.0.0"
+edition = "2018"
+
+[lib]
+name = "rustc_parse"
+path = "lib.rs"
+doctest = false
+
+[dependencies]
+bitflags = "1.0"
+log = "0.4"
+syntax_pos = { path = "../libsyntax_pos" }
+syntax = { path = "../libsyntax" }
+errors = { path = "../librustc_errors", package = "rustc_errors" }
+rustc_data_structures = { path = "../librustc_data_structures" }
+rustc_lexer = { path = "../librustc_lexer" }
+rustc_target = { path = "../librustc_target" }
+smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/librustc_parse/error_codes.rs b/src/librustc_parse/error_codes.rs
new file mode 100644
index 00000000000..cf74e09a377
--- /dev/null
+++ b/src/librustc_parse/error_codes.rs
@@ -0,0 +1,174 @@
+// Error messages for EXXXX errors.
+// Each message should start and end with a new line, and be wrapped to 80
+// characters.  In vim you can `:set tw=80` and use `gq` to wrap paragraphs. Use
+// `:set tw=0` to disable.
+syntax::register_diagnostics! {
+
+E0178: r##"
+In types, the `+` type operator has low precedence, so it is often necessary
+to use parentheses.
+
+For example:
+
+```compile_fail,E0178
+trait Foo {}
+
+struct Bar<'a> {
+    w: &'a Foo + Copy,   // error, use &'a (Foo + Copy)
+    x: &'a Foo + 'a,     // error, use &'a (Foo + 'a)
+    y: &'a mut Foo + 'a, // error, use &'a mut (Foo + 'a)
+    z: fn() -> Foo + 'a, // error, use fn() -> (Foo + 'a)
+}
+```
+
+More details can be found in [RFC 438].
+
+[RFC 438]: https://github.com/rust-lang/rfcs/pull/438
+"##,
+
+E0583: r##"
+A file wasn't found for an out-of-line module.
+
+Erroneous code example:
+
+```ignore (compile_fail not working here; see Issue #43707)
+mod file_that_doesnt_exist; // error: file not found for module
+
+fn main() {}
+```
+
+Please be sure that a file corresponding to the module exists. If you
+want to use a module named `file_that_doesnt_exist`, you need to have a file
+named `file_that_doesnt_exist.rs` or `file_that_doesnt_exist/mod.rs` in the
+same directory.
+"##,
+
+E0584: r##"
+A doc comment that is not attached to anything has been encountered.
+
+Erroneous code example:
+
+```compile_fail,E0584
+trait Island {
+    fn lost();
+
+    /// I'm lost!
+}
+```
+
+A little reminder: a doc comment has to be placed before the item it's supposed
+to document. So if you want to document the `Island` trait, you need to put a
+doc comment before it, not inside it. Same goes for the `lost` method: the doc
+comment needs to be before it:
+
+```
+/// I'm THE island!
+trait Island {
+    /// I'm lost!
+    fn lost();
+}
+```
+"##,
+
+E0585: r##"
+A documentation comment that doesn't document anything was found.
+
+Erroneous code example:
+
+```compile_fail,E0585
+fn main() {
+    // The following doc comment will fail:
+    /// This is a useless doc comment!
+}
+```
+
+Documentation comments need to be followed by items, including functions,
+types, modules, etc. Examples:
+
+```
+/// I'm documenting the following struct:
+struct Foo;
+
+/// I'm documenting the following function:
+fn foo() {}
+```
+"##,
+
+E0586: r##"
+An inclusive range was used with no end.
+
+Erroneous code example:
+
+```compile_fail,E0586
+fn main() {
+    let tmp = vec![0, 1, 2, 3, 4, 4, 3, 3, 2, 1];
+    let x = &tmp[1..=]; // error: inclusive range was used with no end
+}
+```
+
+An inclusive range needs an end in order to *include* it. If you just need a
+start and no end, use a non-inclusive range (with `..`):
+
+```
+fn main() {
+    let tmp = vec![0, 1, 2, 3, 4, 4, 3, 3, 2, 1];
+    let x = &tmp[1..]; // ok!
+}
+```
+
+Or put an end to your inclusive range:
+
+```
+fn main() {
+    let tmp = vec![0, 1, 2, 3, 4, 4, 3, 3, 2, 1];
+    let x = &tmp[1..=3]; // ok!
+}
+```
+"##,
+
+E0704: r##"
+This error indicates that a incorrect visibility restriction was specified.
+
+Example of erroneous code:
+
+```compile_fail,E0704
+mod foo {
+    pub(foo) struct Bar {
+        x: i32
+    }
+}
+```
+
+To make struct `Bar` only visible in module `foo` the `in` keyword should be
+used:
+```
+mod foo {
+    pub(in crate::foo) struct Bar {
+        x: i32
+    }
+}
+# fn main() {}
+```
+
+For more information see the Rust Reference on [Visibility].
+
+[Visibility]: https://doc.rust-lang.org/reference/visibility-and-privacy.html
+"##,
+
+E0743: r##"
+C-variadic has been used on a non-foreign function.
+
+Erroneous code example:
+
+```compile_fail,E0743
+fn foo2(x: u8, ...) {} // error!
+```
+
+Only foreign functions can use C-variadic (`...`). It is used to give an
+undefined number of parameters to a given function (like `printf` in C). The
+equivalent in Rust would be to use macros directly.
+"##,
+
+;
+
+}
diff --git a/src/librustc_parse/lexer/mod.rs b/src/librustc_parse/lexer/mod.rs
new file mode 100644
index 00000000000..5de63cb39d1
--- /dev/null
+++ b/src/librustc_parse/lexer/mod.rs
@@ -0,0 +1,643 @@
+use syntax::token::{self, Token, TokenKind};
+use syntax::sess::ParseSess;
+use syntax::symbol::{sym, Symbol};
+use syntax::util::comments;
+
+use errors::{FatalError, DiagnosticBuilder};
+use syntax_pos::{BytePos, Pos, Span};
+use rustc_lexer::Base;
+use rustc_lexer::unescape;
+
+use std::char;
+use std::convert::TryInto;
+use rustc_data_structures::sync::Lrc;
+use log::debug;
+
+mod tokentrees;
+mod unicode_chars;
+mod unescape_error_reporting;
+use unescape_error_reporting::{emit_unescape_error, push_escaped_char};
+
+#[derive(Clone, Debug)]
+pub struct UnmatchedBrace {
+    pub expected_delim: token::DelimToken,
+    pub found_delim: Option<token::DelimToken>,
+    pub found_span: Span,
+    pub unclosed_span: Option<Span>,
+    pub candidate_span: Option<Span>,
+}
+
+pub struct StringReader<'a> {
+    sess: &'a ParseSess,
+    /// Initial position, read-only.
+    start_pos: BytePos,
+    /// The absolute offset within the source_map of the current character.
+    // FIXME(#64197): `pub` is needed by tests for now.
+    pub pos: BytePos,
+    /// Stop reading src at this index.
+    end_src_index: usize,
+    /// Source text to tokenize.
+    src: Lrc<String>,
+    override_span: Option<Span>,
+}
+
+impl<'a> StringReader<'a> {
+    pub fn new(sess: &'a ParseSess,
+               source_file: Lrc<syntax_pos::SourceFile>,
+               override_span: Option<Span>) -> Self {
+        if source_file.src.is_none() {
+            sess.span_diagnostic.bug(&format!("cannot lex `source_file` without source: {}",
+                                              source_file.name));
+        }
+
+        let src = (*source_file.src.as_ref().unwrap()).clone();
+
+        StringReader {
+            sess,
+            start_pos: source_file.start_pos,
+            pos: source_file.start_pos,
+            end_src_index: src.len(),
+            src,
+            override_span,
+        }
+    }
+
+    pub fn retokenize(sess: &'a ParseSess, mut span: Span) -> Self {
+        let begin = sess.source_map().lookup_byte_offset(span.lo());
+        let end = sess.source_map().lookup_byte_offset(span.hi());
+
+        // Make the range zero-length if the span is invalid.
+        if begin.sf.start_pos != end.sf.start_pos {
+            span = span.shrink_to_lo();
+        }
+
+        let mut sr = StringReader::new(sess, begin.sf, None);
+
+        // Seek the lexer to the right byte range.
+        sr.end_src_index = sr.src_index(span.hi());
+
+        sr
+    }
+
+
+    fn mk_sp(&self, lo: BytePos, hi: BytePos) -> Span {
+        self.override_span.unwrap_or_else(|| Span::with_root_ctxt(lo, hi))
+    }
+
+    /// Returns the next token, including trivia like whitespace or comments.
+    ///
+    /// `Err(())` means that some errors were encountered, which can be
+    /// retrieved using `buffer_fatal_errors`.
+    pub fn next_token(&mut self) -> Token {
+        let start_src_index = self.src_index(self.pos);
+        let text: &str = &self.src[start_src_index..self.end_src_index];
+
+        if text.is_empty() {
+            let span = self.mk_sp(self.pos, self.pos);
+            return Token::new(token::Eof, span);
+        }
+
+        {
+            let is_beginning_of_file = self.pos == self.start_pos;
+            if is_beginning_of_file {
+                if let Some(shebang_len) = rustc_lexer::strip_shebang(text) {
+                    let start = self.pos;
+                    self.pos = self.pos + BytePos::from_usize(shebang_len);
+
+                    let sym = self.symbol_from(start + BytePos::from_usize("#!".len()));
+                    let kind = token::Shebang(sym);
+
+                    let span = self.mk_sp(start, self.pos);
+                    return Token::new(kind, span);
+                }
+            }
+        }
+
+        let token = rustc_lexer::first_token(text);
+
+        let start = self.pos;
+        self.pos = self.pos + BytePos::from_usize(token.len);
+
+        debug!("try_next_token: {:?}({:?})", token.kind, self.str_from(start));
+
+        // This could use `?`, but that makes code significantly (10-20%) slower.
+        // https://github.com/rust-lang/rust/issues/37939
+        let kind = self.cook_lexer_token(token.kind, start);
+
+        let span = self.mk_sp(start, self.pos);
+        Token::new(kind, span)
+    }
+
+    /// Report a fatal lexical error with a given span.
+    fn fatal_span(&self, sp: Span, m: &str) -> FatalError {
+        self.sess.span_diagnostic.span_fatal(sp, m)
+    }
+
+    /// Report a lexical error with a given span.
+    fn err_span(&self, sp: Span, m: &str) {
+        self.sess.span_diagnostic.struct_span_err(sp, m).emit();
+    }
+
+
+    /// Report a fatal error spanning [`from_pos`, `to_pos`).
+    fn fatal_span_(&self, from_pos: BytePos, to_pos: BytePos, m: &str) -> FatalError {
+        self.fatal_span(self.mk_sp(from_pos, to_pos), m)
+    }
+
+    /// Report a lexical error spanning [`from_pos`, `to_pos`).
+    fn err_span_(&self, from_pos: BytePos, to_pos: BytePos, m: &str) {
+        self.err_span(self.mk_sp(from_pos, to_pos), m)
+    }
+
+    fn struct_span_fatal(&self, from_pos: BytePos, to_pos: BytePos, m: &str)
+        -> DiagnosticBuilder<'a>
+    {
+        self.sess.span_diagnostic.struct_span_fatal(self.mk_sp(from_pos, to_pos), m)
+    }
+
+    fn struct_fatal_span_char(&self, from_pos: BytePos, to_pos: BytePos, m: &str, c: char)
+        -> DiagnosticBuilder<'a>
+    {
+        let mut m = m.to_string();
+        m.push_str(": ");
+        push_escaped_char(&mut m, c);
+
+        self.sess.span_diagnostic.struct_span_fatal(self.mk_sp(from_pos, to_pos), &m[..])
+    }
+
+    /// Turns simple `rustc_lexer::TokenKind` enum into a rich
+    /// `libsyntax::TokenKind`. This turns strings into interned
+    /// symbols and runs additional validation.
+    fn cook_lexer_token(
+        &self,
+        token: rustc_lexer::TokenKind,
+        start: BytePos,
+    ) -> TokenKind {
+        match token {
+            rustc_lexer::TokenKind::LineComment => {
+                let string = self.str_from(start);
+                // comments with only more "/"s are not doc comments
+                let tok = if comments::is_line_doc_comment(string) {
+                    self.forbid_bare_cr(start, string, "bare CR not allowed in doc-comment");
+                    token::DocComment(Symbol::intern(string))
+                } else {
+                    token::Comment
+                };
+
+                tok
+            }
+            rustc_lexer::TokenKind::BlockComment { terminated } => {
+                let string = self.str_from(start);
+                // block comments starting with "/**" or "/*!" are doc-comments
+                // but comments with only "*"s between two "/"s are not
+                let is_doc_comment = comments::is_block_doc_comment(string);
+
+                if !terminated {
+                    let msg = if is_doc_comment {
+                        "unterminated block doc-comment"
+                    } else {
+                        "unterminated block comment"
+                    };
+                    let last_bpos = self.pos;
+                    self.fatal_span_(start, last_bpos, msg).raise();
+                }
+
+                let tok = if is_doc_comment {
+                    self.forbid_bare_cr(start,
+                                        string,
+                                        "bare CR not allowed in block doc-comment");
+                    token::DocComment(Symbol::intern(string))
+                } else {
+                    token::Comment
+                };
+
+                tok
+            }
+            rustc_lexer::TokenKind::Whitespace => token::Whitespace,
+            rustc_lexer::TokenKind::Ident | rustc_lexer::TokenKind::RawIdent => {
+                let is_raw_ident = token == rustc_lexer::TokenKind::RawIdent;
+                let mut ident_start = start;
+                if is_raw_ident {
+                    ident_start = ident_start + BytePos(2);
+                }
+                // FIXME: perform NFKC normalization here. (Issue #2253)
+                let sym = self.symbol_from(ident_start);
+                if is_raw_ident {
+                    let span = self.mk_sp(start, self.pos);
+                    if !sym.can_be_raw() {
+                        self.err_span(span, &format!("`{}` cannot be a raw identifier", sym));
+                    }
+                    self.sess.raw_identifier_spans.borrow_mut().push(span);
+                }
+                token::Ident(sym, is_raw_ident)
+            }
+            rustc_lexer::TokenKind::Literal { kind, suffix_start } => {
+                let suffix_start = start + BytePos(suffix_start as u32);
+                let (kind, symbol) = self.cook_lexer_literal(start, suffix_start, kind);
+                let suffix = if suffix_start < self.pos {
+                    let string = self.str_from(suffix_start);
+                    if string == "_" {
+                        self.sess.span_diagnostic
+                            .struct_span_warn(self.mk_sp(suffix_start, self.pos),
+                                              "underscore literal suffix is not allowed")
+                            .warn("this was previously accepted by the compiler but is \
+                                   being phased out; it will become a hard error in \
+                                   a future release!")
+                            .note("for more information, see issue #42326 \
+                                   <https://github.com/rust-lang/rust/issues/42326>")
+                            .emit();
+                        None
+                    } else {
+                        Some(Symbol::intern(string))
+                    }
+                } else {
+                    None
+                };
+                token::Literal(token::Lit { kind, symbol, suffix })
+            }
+            rustc_lexer::TokenKind::Lifetime { starts_with_number } => {
+                // Include the leading `'` in the real identifier, for macro
+                // expansion purposes. See #12512 for the gory details of why
+                // this is necessary.
+                let lifetime_name = self.str_from(start);
+                if starts_with_number {
+                    self.err_span_(
+                        start,
+                        self.pos,
+                        "lifetimes cannot start with a number",
+                    );
+                }
+                let ident = Symbol::intern(lifetime_name);
+                token::Lifetime(ident)
+            }
+            rustc_lexer::TokenKind::Semi => token::Semi,
+            rustc_lexer::TokenKind::Comma => token::Comma,
+            rustc_lexer::TokenKind::Dot => token::Dot,
+            rustc_lexer::TokenKind::OpenParen => token::OpenDelim(token::Paren),
+            rustc_lexer::TokenKind::CloseParen => token::CloseDelim(token::Paren),
+            rustc_lexer::TokenKind::OpenBrace => token::OpenDelim(token::Brace),
+            rustc_lexer::TokenKind::CloseBrace => token::CloseDelim(token::Brace),
+            rustc_lexer::TokenKind::OpenBracket => token::OpenDelim(token::Bracket),
+            rustc_lexer::TokenKind::CloseBracket => token::CloseDelim(token::Bracket),
+            rustc_lexer::TokenKind::At => token::At,
+            rustc_lexer::TokenKind::Pound => token::Pound,
+            rustc_lexer::TokenKind::Tilde => token::Tilde,
+            rustc_lexer::TokenKind::Question => token::Question,
+            rustc_lexer::TokenKind::Colon => token::Colon,
+            rustc_lexer::TokenKind::Dollar => token::Dollar,
+            rustc_lexer::TokenKind::Eq => token::Eq,
+            rustc_lexer::TokenKind::Not => token::Not,
+            rustc_lexer::TokenKind::Lt => token::Lt,
+            rustc_lexer::TokenKind::Gt => token::Gt,
+            rustc_lexer::TokenKind::Minus => token::BinOp(token::Minus),
+            rustc_lexer::TokenKind::And => token::BinOp(token::And),
+            rustc_lexer::TokenKind::Or => token::BinOp(token::Or),
+            rustc_lexer::TokenKind::Plus => token::BinOp(token::Plus),
+            rustc_lexer::TokenKind::Star => token::BinOp(token::Star),
+            rustc_lexer::TokenKind::Slash => token::BinOp(token::Slash),
+            rustc_lexer::TokenKind::Caret => token::BinOp(token::Caret),
+            rustc_lexer::TokenKind::Percent => token::BinOp(token::Percent),
+
+            rustc_lexer::TokenKind::Unknown => {
+                let c = self.str_from(start).chars().next().unwrap();
+                let mut err = self.struct_fatal_span_char(start,
+                                                          self.pos,
+                                                          "unknown start of token",
+                                                          c);
+                // FIXME: the lexer could be used to turn the ASCII version of unicode homoglyphs,
+                // instead of keeping a table in `check_for_substitution`into the token. Ideally,
+                // this should be inside `rustc_lexer`. However, we should first remove compound
+                // tokens like `<<` from `rustc_lexer`, and then add fancier error recovery to it,
+                // as there will be less overall work to do this way.
+                let token = unicode_chars::check_for_substitution(self, start, c, &mut err)
+                    .unwrap_or_else(|| token::Unknown(self.symbol_from(start)));
+                err.emit();
+                token
+            }
+        }
+    }
+
+    fn cook_lexer_literal(
+        &self,
+        start: BytePos,
+        suffix_start: BytePos,
+        kind: rustc_lexer::LiteralKind
+    ) -> (token::LitKind, Symbol) {
+        match kind {
+            rustc_lexer::LiteralKind::Char { terminated } => {
+                if !terminated {
+                    self.fatal_span_(start, suffix_start,
+                                     "unterminated character literal".into())
+                        .raise()
+                }
+                let content_start = start + BytePos(1);
+                let content_end = suffix_start - BytePos(1);
+                self.validate_char_escape(content_start, content_end);
+                let id = self.symbol_from_to(content_start, content_end);
+                (token::Char, id)
+            },
+            rustc_lexer::LiteralKind::Byte { terminated } => {
+                if !terminated {
+                    self.fatal_span_(start + BytePos(1), suffix_start,
+                                     "unterminated byte constant".into())
+                        .raise()
+                }
+                let content_start = start + BytePos(2);
+                let content_end = suffix_start - BytePos(1);
+                self.validate_byte_escape(content_start, content_end);
+                let id = self.symbol_from_to(content_start, content_end);
+                (token::Byte, id)
+            },
+            rustc_lexer::LiteralKind::Str { terminated } => {
+                if !terminated {
+                    self.fatal_span_(start, suffix_start,
+                                     "unterminated double quote string".into())
+                        .raise()
+                }
+                let content_start = start + BytePos(1);
+                let content_end = suffix_start - BytePos(1);
+                self.validate_str_escape(content_start, content_end);
+                let id = self.symbol_from_to(content_start, content_end);
+                (token::Str, id)
+            }
+            rustc_lexer::LiteralKind::ByteStr { terminated } => {
+                if !terminated {
+                    self.fatal_span_(start + BytePos(1), suffix_start,
+                                     "unterminated double quote byte string".into())
+                        .raise()
+                }
+                let content_start = start + BytePos(2);
+                let content_end = suffix_start - BytePos(1);
+                self.validate_byte_str_escape(content_start, content_end);
+                let id = self.symbol_from_to(content_start, content_end);
+                (token::ByteStr, id)
+            }
+            rustc_lexer::LiteralKind::RawStr { n_hashes, started, terminated } => {
+                if !started {
+                    self.report_non_started_raw_string(start);
+                }
+                if !terminated {
+                    self.report_unterminated_raw_string(start, n_hashes)
+                }
+                let n_hashes: u16 = self.restrict_n_hashes(start, n_hashes);
+                let n = u32::from(n_hashes);
+                let content_start = start + BytePos(2 + n);
+                let content_end = suffix_start - BytePos(1 + n);
+                self.validate_raw_str_escape(content_start, content_end);
+                let id = self.symbol_from_to(content_start, content_end);
+                (token::StrRaw(n_hashes), id)
+            }
+            rustc_lexer::LiteralKind::RawByteStr { n_hashes, started, terminated } => {
+                if !started {
+                    self.report_non_started_raw_string(start);
+                }
+                if !terminated {
+                    self.report_unterminated_raw_string(start, n_hashes)
+                }
+                let n_hashes: u16 = self.restrict_n_hashes(start, n_hashes);
+                let n = u32::from(n_hashes);
+                let content_start = start + BytePos(3 + n);
+                let content_end = suffix_start - BytePos(1 + n);
+                self.validate_raw_byte_str_escape(content_start, content_end);
+                let id = self.symbol_from_to(content_start, content_end);
+                (token::ByteStrRaw(n_hashes), id)
+            }
+            rustc_lexer::LiteralKind::Int { base, empty_int } => {
+                if empty_int {
+                    self.err_span_(start, suffix_start, "no valid digits found for number");
+                    (token::Integer, sym::integer(0))
+                } else {
+                    self.validate_int_literal(base, start, suffix_start);
+                    (token::Integer, self.symbol_from_to(start, suffix_start))
+                }
+            },
+            rustc_lexer::LiteralKind::Float { base, empty_exponent } => {
+                if empty_exponent {
+                    let mut err = self.struct_span_fatal(
+                        start, self.pos,
+                        "expected at least one digit in exponent"
+                    );
+                    err.emit();
+                }
+
+                match base {
+                    Base::Hexadecimal => {
+                        self.err_span_(start, suffix_start,
+                                       "hexadecimal float literal is not supported")
+                    }
+                    Base::Octal => {
+                        self.err_span_(start, suffix_start,
+                                       "octal float literal is not supported")
+                    }
+                    Base::Binary => {
+                        self.err_span_(start, suffix_start,
+                                       "binary float literal is not supported")
+                    }
+                    _ => ()
+                }
+
+                let id = self.symbol_from_to(start, suffix_start);
+                (token::Float, id)
+            },
+        }
+    }
+
+    #[inline]
+    fn src_index(&self, pos: BytePos) -> usize {
+        (pos - self.start_pos).to_usize()
+    }
+
+    /// Slice of the source text from `start` up to but excluding `self.pos`,
+    /// meaning the slice does not include the character `self.ch`.
+    fn str_from(&self, start: BytePos) -> &str
+    {
+        self.str_from_to(start, self.pos)
+    }
+
+    /// Creates a Symbol from a given offset to the current offset.
+    fn symbol_from(&self, start: BytePos) -> Symbol {
+        debug!("taking an ident from {:?} to {:?}", start, self.pos);
+        Symbol::intern(self.str_from(start))
+    }
+
+    /// As symbol_from, with an explicit endpoint.
+    fn symbol_from_to(&self, start: BytePos, end: BytePos) -> Symbol {
+        debug!("taking an ident from {:?} to {:?}", start, end);
+        Symbol::intern(self.str_from_to(start, end))
+    }
+
+    /// Slice of the source text spanning from `start` up to but excluding `end`.
+    fn str_from_to(&self, start: BytePos, end: BytePos) -> &str
+    {
+        &self.src[self.src_index(start)..self.src_index(end)]
+    }
+
+    fn forbid_bare_cr(&self, start: BytePos, s: &str, errmsg: &str) {
+        let mut idx = 0;
+        loop {
+            idx = match s[idx..].find('\r') {
+                None => break,
+                Some(it) => idx + it + 1
+            };
+            self.err_span_(start + BytePos(idx as u32 - 1),
+                           start + BytePos(idx as u32),
+                           errmsg);
+        }
+    }
+
+    fn report_non_started_raw_string(&self, start: BytePos) -> ! {
+        let bad_char = self.str_from(start).chars().last().unwrap();
+        self
+            .struct_fatal_span_char(
+                start,
+                self.pos,
+                "found invalid character; only `#` is allowed \
+                 in raw string delimitation",
+                bad_char,
+            )
+            .emit();
+        FatalError.raise()
+    }
+
+    fn report_unterminated_raw_string(&self, start: BytePos, n_hashes: usize) -> ! {
+        let mut err = self.struct_span_fatal(
+            start, start,
+            "unterminated raw string",
+        );
+        err.span_label(
+            self.mk_sp(start, start),
+            "unterminated raw string",
+        );
+
+        if n_hashes > 0 {
+            err.note(&format!("this raw string should be terminated with `\"{}`",
+                                "#".repeat(n_hashes as usize)));
+        }
+
+        err.emit();
+        FatalError.raise()
+    }
+
+    fn restrict_n_hashes(&self, start: BytePos, n_hashes: usize) -> u16 {
+        match n_hashes.try_into() {
+            Ok(n_hashes) => n_hashes,
+            Err(_) => {
+                self.fatal_span_(start,
+                                 self.pos,
+                                 "too many `#` symbols: raw strings may be \
+                                  delimited by up to 65535 `#` symbols").raise();
+            }
+        }
+    }
+
+    fn validate_char_escape(&self, content_start: BytePos, content_end: BytePos) {
+        let lit = self.str_from_to(content_start, content_end);
+        if let Err((off, err)) = unescape::unescape_char(lit) {
+            emit_unescape_error(
+                &self.sess.span_diagnostic,
+                lit,
+                self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
+                unescape::Mode::Char,
+                0..off,
+                err,
+            )
+        }
+    }
+
+    fn validate_byte_escape(&self, content_start: BytePos, content_end: BytePos) {
+        let lit = self.str_from_to(content_start, content_end);
+        if let Err((off, err)) = unescape::unescape_byte(lit) {
+            emit_unescape_error(
+                &self.sess.span_diagnostic,
+                lit,
+                self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
+                unescape::Mode::Byte,
+                0..off,
+                err,
+            )
+        }
+    }
+
+    fn validate_str_escape(&self, content_start: BytePos, content_end: BytePos) {
+        let lit = self.str_from_to(content_start, content_end);
+        unescape::unescape_str(lit, &mut |range, c| {
+            if let Err(err) = c {
+                emit_unescape_error(
+                    &self.sess.span_diagnostic,
+                    lit,
+                    self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
+                    unescape::Mode::Str,
+                    range,
+                    err,
+                )
+            }
+        })
+    }
+
+    fn validate_raw_str_escape(&self, content_start: BytePos, content_end: BytePos) {
+        let lit = self.str_from_to(content_start, content_end);
+        unescape::unescape_raw_str(lit, &mut |range, c| {
+            if let Err(err) = c {
+                emit_unescape_error(
+                    &self.sess.span_diagnostic,
+                    lit,
+                    self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
+                    unescape::Mode::Str,
+                    range,
+                    err,
+                )
+            }
+        })
+    }
+
+    fn validate_raw_byte_str_escape(&self, content_start: BytePos, content_end: BytePos) {
+        let lit = self.str_from_to(content_start, content_end);
+        unescape::unescape_raw_byte_str(lit, &mut |range, c| {
+            if let Err(err) = c {
+                emit_unescape_error(
+                    &self.sess.span_diagnostic,
+                    lit,
+                    self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
+                    unescape::Mode::ByteStr,
+                    range,
+                    err,
+                )
+            }
+        })
+    }
+
+    fn validate_byte_str_escape(&self, content_start: BytePos, content_end: BytePos) {
+        let lit = self.str_from_to(content_start, content_end);
+        unescape::unescape_byte_str(lit, &mut |range, c| {
+            if let Err(err) = c {
+                emit_unescape_error(
+                    &self.sess.span_diagnostic,
+                    lit,
+                    self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
+                    unescape::Mode::ByteStr,
+                    range,
+                    err,
+                )
+            }
+        })
+    }
+
+    fn validate_int_literal(&self, base: Base, content_start: BytePos, content_end: BytePos) {
+        let base = match base {
+            Base::Binary => 2,
+            Base::Octal => 8,
+            _ => return,
+        };
+        let s = self.str_from_to(content_start + BytePos(2), content_end);
+        for (idx, c) in s.char_indices() {
+            let idx = idx as u32;
+            if c != '_' && c.to_digit(base).is_none() {
+                let lo = content_start + BytePos(2 + idx);
+                let hi = content_start + BytePos(2 + idx + c.len_utf8() as u32);
+                self.err_span_(lo, hi,
+                               &format!("invalid digit for a base {} literal", base));
+
+            }
+        }
+    }
+}
diff --git a/src/librustc_parse/lexer/tokentrees.rs b/src/librustc_parse/lexer/tokentrees.rs
new file mode 100644
index 00000000000..1353591308b
--- /dev/null
+++ b/src/librustc_parse/lexer/tokentrees.rs
@@ -0,0 +1,280 @@
+use rustc_data_structures::fx::FxHashMap;
+use syntax_pos::Span;
+
+use super::{StringReader, UnmatchedBrace};
+
+use syntax::print::pprust::token_to_string;
+use syntax::token::{self, Token};
+use syntax::tokenstream::{DelimSpan, IsJoint::{self, *}, TokenStream, TokenTree, TreeAndJoint};
+
+use errors::PResult;
+
+impl<'a> StringReader<'a> {
+    crate fn into_token_trees(self) -> (PResult<'a, TokenStream>, Vec<UnmatchedBrace>) {
+        let mut tt_reader = TokenTreesReader {
+            string_reader: self,
+            token: Token::dummy(),
+            joint_to_prev: Joint,
+            open_braces: Vec::new(),
+            unmatched_braces: Vec::new(),
+            matching_delim_spans: Vec::new(),
+            last_unclosed_found_span: None,
+            last_delim_empty_block_spans: FxHashMap::default()
+        };
+        let res = tt_reader.parse_all_token_trees();
+        (res, tt_reader.unmatched_braces)
+    }
+}
+
+struct TokenTreesReader<'a> {
+    string_reader: StringReader<'a>,
+    token: Token,
+    joint_to_prev: IsJoint,
+    /// Stack of open delimiters and their spans. Used for error message.
+    open_braces: Vec<(token::DelimToken, Span)>,
+    unmatched_braces: Vec<UnmatchedBrace>,
+    /// The type and spans for all braces
+    ///
+    /// Used only for error recovery when arriving to EOF with mismatched braces.
+    matching_delim_spans: Vec<(token::DelimToken, Span, Span)>,
+    last_unclosed_found_span: Option<Span>,
+    last_delim_empty_block_spans: FxHashMap<token::DelimToken, Span>
+}
+
+impl<'a> TokenTreesReader<'a> {
+    // Parse a stream of tokens into a list of `TokenTree`s, up to an `Eof`.
+    fn parse_all_token_trees(&mut self) -> PResult<'a, TokenStream> {
+        let mut buf = TokenStreamBuilder::default();
+
+        self.real_token();
+        while self.token != token::Eof {
+            buf.push(self.parse_token_tree()?);
+        }
+
+        Ok(buf.into_token_stream())
+    }
+
+    // Parse a stream of tokens into a list of `TokenTree`s, up to a `CloseDelim`.
+    fn parse_token_trees_until_close_delim(&mut self) -> TokenStream {
+        let mut buf = TokenStreamBuilder::default();
+        loop {
+            if let token::CloseDelim(..) = self.token.kind {
+                return buf.into_token_stream();
+            }
+
+            match self.parse_token_tree() {
+                Ok(tree) => buf.push(tree),
+                Err(mut e) => {
+                    e.emit();
+                    return buf.into_token_stream();
+                }
+            }
+        }
+    }
+
+    fn parse_token_tree(&mut self) -> PResult<'a, TreeAndJoint> {
+        let sm = self.string_reader.sess.source_map();
+        match self.token.kind {
+            token::Eof => {
+                let msg = "this file contains an un-closed delimiter";
+                let mut err = self.string_reader.sess.span_diagnostic
+                    .struct_span_err(self.token.span, msg);
+                for &(_, sp) in &self.open_braces {
+                    err.span_label(sp, "un-closed delimiter");
+                    self.unmatched_braces.push(UnmatchedBrace {
+                        expected_delim: token::DelimToken::Brace,
+                        found_delim: None,
+                        found_span: self.token.span,
+                        unclosed_span: Some(sp),
+                        candidate_span: None,
+                    });
+                }
+
+                if let Some((delim, _)) = self.open_braces.last() {
+                    if let Some((_, open_sp, close_sp)) = self.matching_delim_spans.iter()
+                        .filter(|(d, open_sp, close_sp)| {
+                            if let Some(close_padding) = sm.span_to_margin(*close_sp) {
+                                if let Some(open_padding) = sm.span_to_margin(*open_sp) {
+                                    return delim == d && close_padding != open_padding;
+                                }
+                            }
+                            false
+                        }).next()  // these are in reverse order as they get inserted on close, but
+                    {              // we want the last open/first close
+                        err.span_label(
+                            *open_sp,
+                            "this delimiter might not be properly closed...",
+                        );
+                        err.span_label(
+                            *close_sp,
+                            "...as it matches this but it has different indentation",
+                        );
+                    }
+                }
+                Err(err)
+            },
+            token::OpenDelim(delim) => {
+                // The span for beginning of the delimited section
+                let pre_span = self.token.span;
+
+                // Parse the open delimiter.
+                self.open_braces.push((delim, self.token.span));
+                self.real_token();
+
+                // Parse the token trees within the delimiters.
+                // We stop at any delimiter so we can try to recover if the user
+                // uses an incorrect delimiter.
+                let tts = self.parse_token_trees_until_close_delim();
+
+                // Expand to cover the entire delimited token tree
+                let delim_span = DelimSpan::from_pair(pre_span, self.token.span);
+
+                match self.token.kind {
+                    // Correct delimiter.
+                    token::CloseDelim(d) if d == delim => {
+                        let (open_brace, open_brace_span) = self.open_braces.pop().unwrap();
+                        let close_brace_span = self.token.span;
+
+                        if tts.is_empty() {
+                            let empty_block_span = open_brace_span.to(close_brace_span);
+                            self.last_delim_empty_block_spans.insert(delim, empty_block_span);
+                        }
+
+                        if self.open_braces.len() == 0 {
+                            // Clear up these spans to avoid suggesting them as we've found
+                            // properly matched delimiters so far for an entire block.
+                            self.matching_delim_spans.clear();
+                        } else {
+                            self.matching_delim_spans.push(
+                                (open_brace, open_brace_span, close_brace_span),
+                            );
+                        }
+                        // Parse the close delimiter.
+                        self.real_token();
+                    }
+                    // Incorrect delimiter.
+                    token::CloseDelim(other) => {
+                        let mut unclosed_delimiter = None;
+                        let mut candidate = None;
+                        if self.last_unclosed_found_span != Some(self.token.span) {
+                            // do not complain about the same unclosed delimiter multiple times
+                            self.last_unclosed_found_span = Some(self.token.span);
+                            // This is a conservative error: only report the last unclosed
+                            // delimiter. The previous unclosed delimiters could actually be
+                            // closed! The parser just hasn't gotten to them yet.
+                            if let Some(&(_, sp)) = self.open_braces.last() {
+                                unclosed_delimiter = Some(sp);
+                            };
+                            if let Some(current_padding) = sm.span_to_margin(self.token.span) {
+                                for (brace, brace_span) in &self.open_braces {
+                                    if let Some(padding) = sm.span_to_margin(*brace_span) {
+                                        // high likelihood of these two corresponding
+                                        if current_padding == padding && brace == &other {
+                                            candidate = Some(*brace_span);
+                                        }
+                                    }
+                                }
+                            }
+                            let (tok, _) = self.open_braces.pop().unwrap();
+                            self.unmatched_braces.push(UnmatchedBrace {
+                                expected_delim: tok,
+                                found_delim: Some(other),
+                                found_span: self.token.span,
+                                unclosed_span: unclosed_delimiter,
+                                candidate_span: candidate,
+                            });
+                        } else {
+                            self.open_braces.pop();
+                        }
+
+                        // If the incorrect delimiter matches an earlier opening
+                        // delimiter, then don't consume it (it can be used to
+                        // close the earlier one). Otherwise, consume it.
+                        // E.g., we try to recover from:
+                        // fn foo() {
+                        //     bar(baz(
+                        // }  // Incorrect delimiter but matches the earlier `{`
+                        if !self.open_braces.iter().any(|&(b, _)| b == other) {
+                            self.real_token();
+                        }
+                    }
+                    token::Eof => {
+                        // Silently recover, the EOF token will be seen again
+                        // and an error emitted then. Thus we don't pop from
+                        // self.open_braces here.
+                    },
+                    _ => {}
+                }
+
+                Ok(TokenTree::Delimited(
+                    delim_span,
+                    delim,
+                    tts.into()
+                ).into())
+            },
+            token::CloseDelim(delim) => {
+                // An unexpected closing delimiter (i.e., there is no
+                // matching opening delimiter).
+                let token_str = token_to_string(&self.token);
+                let msg = format!("unexpected close delimiter: `{}`", token_str);
+                let mut err = self.string_reader.sess.span_diagnostic
+                    .struct_span_err(self.token.span, &msg);
+
+                if let Some(span) = self.last_delim_empty_block_spans.remove(&delim) {
+                    err.span_label(
+                        span,
+                        "this block is empty, you might have not meant to close it"
+                    );
+                }
+                err.span_label(self.token.span, "unexpected close delimiter");
+                Err(err)
+            },
+            _ => {
+                let tt = TokenTree::Token(self.token.take());
+                self.real_token();
+                let is_joint = self.joint_to_prev == Joint && self.token.is_op();
+                Ok((tt, if is_joint { Joint } else { NonJoint }))
+            }
+        }
+    }
+
+    fn real_token(&mut self) {
+        self.joint_to_prev = Joint;
+        loop {
+            let token = self.string_reader.next_token();
+            match token.kind {
+                token::Whitespace | token::Comment | token::Shebang(_) | token::Unknown(_) => {
+                    self.joint_to_prev = NonJoint;
+                }
+                _ => {
+                    self.token = token;
+                    return;
+                }
+            }
+        }
+    }
+}
+
+#[derive(Default)]
+struct TokenStreamBuilder {
+    buf: Vec<TreeAndJoint>,
+}
+
+impl TokenStreamBuilder {
+    fn push(&mut self, (tree, joint): TreeAndJoint) {
+        if let Some((TokenTree::Token(prev_token), Joint)) = self.buf.last() {
+            if let TokenTree::Token(token) = &tree {
+                if let Some(glued) = prev_token.glue(token) {
+                    self.buf.pop();
+                    self.buf.push((TokenTree::Token(glued), joint));
+                    return;
+                }
+            }
+        }
+        self.buf.push((tree, joint))
+    }
+
+    fn into_token_stream(self) -> TokenStream {
+        TokenStream::new(self.buf)
+    }
+}
diff --git a/src/librustc_parse/lexer/unescape_error_reporting.rs b/src/librustc_parse/lexer/unescape_error_reporting.rs
new file mode 100644
index 00000000000..a5749d07e62
--- /dev/null
+++ b/src/librustc_parse/lexer/unescape_error_reporting.rs
@@ -0,0 +1,215 @@
+//! Utilities for rendering escape sequence errors as diagnostics.
+
+use std::ops::Range;
+use std::iter::once;
+
+use rustc_lexer::unescape::{EscapeError, Mode};
+use syntax_pos::{Span, BytePos};
+
+use syntax::errors::{Handler, Applicability};
+
+pub(crate) fn emit_unescape_error(
+    handler: &Handler,
+    // interior part of the literal, without quotes
+    lit: &str,
+    // full span of the literal, including quotes
+    span_with_quotes: Span,
+    mode: Mode,
+    // range of the error inside `lit`
+    range: Range<usize>,
+    error: EscapeError,
+) {
+    log::debug!("emit_unescape_error: {:?}, {:?}, {:?}, {:?}, {:?}",
+                lit, span_with_quotes, mode, range, error);
+    let span = {
+        let Range { start, end } = range;
+        let (start, end) = (start as u32, end as u32);
+        let lo = span_with_quotes.lo() + BytePos(start + 1);
+        let hi = lo + BytePos(end - start);
+            span_with_quotes
+            .with_lo(lo)
+            .with_hi(hi)
+    };
+    let last_char = || {
+        let c = lit[range.clone()].chars().rev().next().unwrap();
+        let span = span.with_lo(span.hi() - BytePos(c.len_utf8() as u32));
+        (c, span)
+    };
+    match error {
+        EscapeError::LoneSurrogateUnicodeEscape => {
+            handler.struct_span_err(span, "invalid unicode character escape")
+                .help("unicode escape must not be a surrogate")
+                .emit();
+        }
+        EscapeError::OutOfRangeUnicodeEscape => {
+            handler.struct_span_err(span, "invalid unicode character escape")
+                .help("unicode escape must be at most 10FFFF")
+                .emit();
+        }
+        EscapeError::MoreThanOneChar => {
+            let msg = if mode.is_bytes() {
+                "if you meant to write a byte string literal, use double quotes"
+            } else {
+                "if you meant to write a `str` literal, use double quotes"
+            };
+
+            handler
+                .struct_span_err(
+                    span_with_quotes,
+                    "character literal may only contain one codepoint",
+                )
+                .span_suggestion(
+                    span_with_quotes,
+                    msg,
+                    format!("\"{}\"", lit),
+                    Applicability::MachineApplicable,
+                ).emit()
+        }
+        EscapeError::EscapeOnlyChar => {
+            let (c, _span) = last_char();
+
+            let mut msg = if mode.is_bytes() {
+                "byte constant must be escaped: "
+            } else {
+                "character constant must be escaped: "
+            }.to_string();
+            push_escaped_char(&mut msg, c);
+
+            handler.span_err(span, msg.as_str())
+        }
+        EscapeError::BareCarriageReturn => {
+            let msg = if mode.in_double_quotes() {
+                "bare CR not allowed in string, use \\r instead"
+            } else {
+                "character constant must be escaped: \\r"
+            };
+            handler.span_err(span, msg);
+        }
+        EscapeError::BareCarriageReturnInRawString => {
+            assert!(mode.in_double_quotes());
+            let msg = "bare CR not allowed in raw string";
+            handler.span_err(span, msg);
+        }
+        EscapeError::InvalidEscape => {
+            let (c, span) = last_char();
+
+            let label = if mode.is_bytes() {
+                "unknown byte escape"
+            } else {
+                "unknown character escape"
+            };
+            let mut msg = label.to_string();
+            msg.push_str(": ");
+            push_escaped_char(&mut msg, c);
+
+            let mut diag = handler.struct_span_err(span, msg.as_str());
+            diag.span_label(span, label);
+            if c == '{' || c == '}' && !mode.is_bytes() {
+                diag.help("if used in a formatting string, \
+                           curly braces are escaped with `{{` and `}}`");
+            } else if c == '\r' {
+                diag.help("this is an isolated carriage return; \
+                           consider checking your editor and version control settings");
+            }
+            diag.emit();
+        }
+        EscapeError::TooShortHexEscape => {
+            handler.span_err(span, "numeric character escape is too short")
+        }
+        EscapeError::InvalidCharInHexEscape | EscapeError::InvalidCharInUnicodeEscape => {
+            let (c, span) = last_char();
+
+            let mut msg = if error == EscapeError::InvalidCharInHexEscape {
+                "invalid character in numeric character escape: "
+            } else {
+                "invalid character in unicode escape: "
+            }.to_string();
+            push_escaped_char(&mut msg, c);
+
+            handler.span_err(span, msg.as_str())
+        }
+        EscapeError::NonAsciiCharInByte => {
+            assert!(mode.is_bytes());
+            let (_c, span) = last_char();
+            handler.span_err(span, "byte constant must be ASCII. \
+                                    Use a \\xHH escape for a non-ASCII byte")
+        }
+        EscapeError::NonAsciiCharInByteString => {
+            assert!(mode.is_bytes());
+            let (_c, span) = last_char();
+            handler.span_err(span, "raw byte string must be ASCII")
+        }
+        EscapeError::OutOfRangeHexEscape => {
+            handler.span_err(span, "this form of character escape may only be used \
+                                    with characters in the range [\\x00-\\x7f]")
+        }
+        EscapeError::LeadingUnderscoreUnicodeEscape => {
+            let (_c, span) = last_char();
+            handler.span_err(span, "invalid start of unicode escape")
+        }
+        EscapeError::OverlongUnicodeEscape => {
+            handler.span_err(span, "overlong unicode escape (must have at most 6 hex digits)")
+        }
+        EscapeError::UnclosedUnicodeEscape => {
+            handler.span_err(span, "unterminated unicode escape (needed a `}`)")
+        }
+        EscapeError::NoBraceInUnicodeEscape => {
+            let msg = "incorrect unicode escape sequence";
+            let mut diag = handler.struct_span_err(span, msg);
+
+            let mut suggestion = "\\u{".to_owned();
+            let mut suggestion_len = 0;
+            let (c, char_span) = last_char();
+            let chars = once(c).chain(lit[range.end..].chars());
+            for c in chars.take(6).take_while(|c| c.is_digit(16)) {
+                suggestion.push(c);
+                suggestion_len += c.len_utf8();
+            }
+
+            if suggestion_len > 0 {
+                suggestion.push('}');
+                let lo = char_span.lo();
+                let hi = lo + BytePos(suggestion_len as u32);
+                diag.span_suggestion(
+                    span.with_lo(lo).with_hi(hi),
+                    "format of unicode escape sequences uses braces",
+                    suggestion,
+                    Applicability::MaybeIncorrect,
+                );
+            } else {
+                diag.span_label(span, msg);
+                diag.help(
+                    "format of unicode escape sequences is `\\u{...}`",
+                );
+            }
+
+            diag.emit();
+        }
+        EscapeError::UnicodeEscapeInByte => {
+            handler.span_err(span, "unicode escape sequences cannot be used \
+                                    as a byte or in a byte string")
+        }
+        EscapeError::EmptyUnicodeEscape => {
+            handler.span_err(span, "empty unicode escape (must have at least 1 hex digit)")
+        }
+        EscapeError::ZeroChars => {
+            handler.span_err(span, "empty character literal")
+        }
+        EscapeError::LoneSlash => {
+            handler.span_err(span, "invalid trailing slash in literal")
+        }
+    }
+}
+
+/// Pushes a character to a message string for error reporting
+pub(crate) fn push_escaped_char(msg: &mut String, c: char) {
+    match c {
+        '\u{20}'..='\u{7e}' => {
+            // Don't escape \, ' or " for user-facing messages
+            msg.push(c);
+        }
+        _ => {
+            msg.extend(c.escape_default());
+        }
+    }
+}
diff --git a/src/librustc_parse/lexer/unicode_chars.rs b/src/librustc_parse/lexer/unicode_chars.rs
new file mode 100644
index 00000000000..6eb995b61d3
--- /dev/null
+++ b/src/librustc_parse/lexer/unicode_chars.rs
@@ -0,0 +1,392 @@
+// Characters and their corresponding confusables were collected from
+// http://www.unicode.org/Public/security/10.0.0/confusables.txt
+
+use super::StringReader;
+use errors::{Applicability, DiagnosticBuilder};
+use syntax_pos::{BytePos, Pos, Span, symbol::kw};
+use crate::token;
+
+#[rustfmt::skip] // for line breaks
+const UNICODE_ARRAY: &[(char, &str, char)] = &[
+    ('
', "Line Separator", ' '),
+    ('
', "Paragraph Separator", ' '),
+    (' ', "Ogham Space mark", ' '),
+    (' ', "En Quad", ' '),
+    (' ', "Em Quad", ' '),
+    (' ', "En Space", ' '),
+    (' ', "Em Space", ' '),
+    (' ', "Three-Per-Em Space", ' '),
+    (' ', "Four-Per-Em Space", ' '),
+    (' ', "Six-Per-Em Space", ' '),
+    (' ', "Punctuation Space", ' '),
+    (' ', "Thin Space", ' '),
+    (' ', "Hair Space", ' '),
+    (' ', "Medium Mathematical Space", ' '),
+    (' ', "No-Break Space", ' '),
+    (' ', "Figure Space", ' '),
+    (' ', "Narrow No-Break Space", ' '),
+    ('　', "Ideographic Space", ' '),
+
+    ('ߺ', "Nko Lajanyalan", '_'),
+    ('﹍', "Dashed Low Line", '_'),
+    ('﹎', "Centreline Low Line", '_'),
+    ('﹏', "Wavy Low Line", '_'),
+    ('＿', "Fullwidth Low Line", '_'),
+
+    ('‐', "Hyphen", '-'),
+    ('‑', "Non-Breaking Hyphen", '-'),
+    ('‒', "Figure Dash", '-'),
+    ('–', "En Dash", '-'),
+    ('—', "Em Dash", '-'),
+    ('﹘', "Small Em Dash", '-'),
+    ('۔', "Arabic Full Stop", '-'),
+    ('⁃', "Hyphen Bullet", '-'),
+    ('˗', "Modifier Letter Minus Sign", '-'),
+    ('−', "Minus Sign", '-'),
+    ('➖', "Heavy Minus Sign", '-'),
+    ('Ⲻ', "Coptic Letter Dialect-P Ni", '-'),
+    ('ー', "Katakana-Hiragana Prolonged Sound Mark", '-'),
+    ('－', "Fullwidth Hyphen-Minus", '-'),
+    ('―', "Horizontal Bar", '-'),
+    ('─', "Box Drawings Light Horizontal", '-'),
+    ('━', "Box Drawings Heavy Horizontal", '-'),
+    ('㇐', "CJK Stroke H", '-'),
+    ('ꟷ', "Latin Epigraphic Letter Sideways I", '-'),
+    ('ᅳ', "Hangul Jungseong Eu", '-'),
+    ('ㅡ', "Hangul Letter Eu", '-'),
+    ('一', "CJK Unified Ideograph-4E00", '-'),
+    ('⼀', "Kangxi Radical One", '-'),
+
+    ('؍', "Arabic Date Separator", ','),
+    ('٫', "Arabic Decimal Separator", ','),
+    ('‚', "Single Low-9 Quotation Mark", ','),
+    ('¸', "Cedilla", ','),
+    ('ꓹ', "Lisu Letter Tone Na Po", ','),
+    ('，', "Fullwidth Comma", ','),
+
+    (';', "Greek Question Mark", ';'),
+    ('；', "Fullwidth Semicolon", ';'),
+    ('︔', "Presentation Form For Vertical Semicolon", ';'),
+
+    ('ः', "Devanagari Sign Visarga", ':'),
+    ('ઃ', "Gujarati Sign Visarga", ':'),
+    ('：', "Fullwidth Colon", ':'),
+    ('։', "Armenian Full Stop", ':'),
+    ('܃', "Syriac Supralinear Colon", ':'),
+    ('܄', "Syriac Sublinear Colon", ':'),
+    ('᛬', "Runic Multiple Punctuation", ':'),
+    ('︰', "Presentation Form For Vertical Two Dot Leader", ':'),
+    ('᠃', "Mongolian Full Stop", ':'),
+    ('᠉', "Mongolian Manchu Full Stop", ':'),
+    ('⁚', "Two Dot Punctuation", ':'),
+    ('׃', "Hebrew Punctuation Sof Pasuq", ':'),
+    ('˸', "Modifier Letter Raised Colon", ':'),
+    ('꞉', "Modifier Letter Colon", ':'),
+    ('∶', "Ratio", ':'),
+    ('ː', "Modifier Letter Triangular Colon", ':'),
+    ('ꓽ', "Lisu Letter Tone Mya Jeu", ':'),
+    ('︓', "Presentation Form For Vertical Colon", ':'),
+
+    ('！', "Fullwidth Exclamation Mark", '!'),
+    ('ǃ', "Latin Letter Retroflex Click", '!'),
+    ('ⵑ', "Tifinagh Letter Tuareg Yang", '!'),
+    ('︕', "Presentation Form For Vertical Exclamation Mark", '!'),
+
+    ('ʔ', "Latin Letter Glottal Stop", '?'),
+    ('Ɂ', "Latin Capital Letter Glottal Stop", '?'),
+    ('ॽ', "Devanagari Letter Glottal Stop", '?'),
+    ('Ꭾ', "Cherokee Letter He", '?'),
+    ('ꛫ', "Bamum Letter Ntuu", '?'),
+    ('？', "Fullwidth Question Mark", '?'),
+    ('︖', "Presentation Form For Vertical Question Mark", '?'),
+
+    ('𝅭', "Musical Symbol Combining Augmentation Dot", '.'),
+    ('․', "One Dot Leader", '.'),
+    ('܁', "Syriac Supralinear Full Stop", '.'),
+    ('܂', "Syriac Sublinear Full Stop", '.'),
+    ('꘎', "Vai Full Stop", '.'),
+    ('𐩐', "Kharoshthi Punctuation Dot", '.'),
+    ('٠', "Arabic-Indic Digit Zero", '.'),
+    ('۰', "Extended Arabic-Indic Digit Zero", '.'),
+    ('ꓸ', "Lisu Letter Tone Mya Ti", '.'),
+    ('·', "Middle Dot", '.'),
+    ('・', "Katakana Middle Dot", '.'),
+    ('･', "Halfwidth Katakana Middle Dot", '.'),
+    ('᛫', "Runic Single Punctuation", '.'),
+    ('·', "Greek Ano Teleia", '.'),
+    ('⸱', "Word Separator Middle Dot", '.'),
+    ('𐄁', "Aegean Word Separator Dot", '.'),
+    ('•', "Bullet", '.'),
+    ('‧', "Hyphenation Point", '.'),
+    ('∙', "Bullet Operator", '.'),
+    ('⋅', "Dot Operator", '.'),
+    ('ꞏ', "Latin Letter Sinological Dot", '.'),
+    ('ᐧ', "Canadian Syllabics Final Middle Dot", '.'),
+    ('ᐧ', "Canadian Syllabics Final Middle Dot", '.'),
+    ('．', "Fullwidth Full Stop", '.'),
+    ('。', "Ideographic Full Stop", '.'),
+    ('︒', "Presentation Form For Vertical Ideographic Full Stop", '.'),
+
+    ('՝', "Armenian Comma", '\''),
+    ('＇', "Fullwidth Apostrophe", '\''),
+    ('‘', "Left Single Quotation Mark", '\''),
+    ('’', "Right Single Quotation Mark", '\''),
+    ('‛', "Single High-Reversed-9 Quotation Mark", '\''),
+    ('′', "Prime", '\''),
+    ('‵', "Reversed Prime", '\''),
+    ('՚', "Armenian Apostrophe", '\''),
+    ('׳', "Hebrew Punctuation Geresh", '\''),
+    ('`', "Grave Accent", '\''),
+    ('`', "Greek Varia", '\''),
+    ('｀', "Fullwidth Grave Accent", '\''),
+    ('´', "Acute Accent", '\''),
+    ('΄', "Greek Tonos", '\''),
+    ('´', "Greek Oxia", '\''),
+    ('᾽', "Greek Koronis", '\''),
+    ('᾿', "Greek Psili", '\''),
+    ('῾', "Greek Dasia", '\''),
+    ('ʹ', "Modifier Letter Prime", '\''),
+    ('ʹ', "Greek Numeral Sign", '\''),
+    ('ˈ', "Modifier Letter Vertical Line", '\''),
+    ('ˊ', "Modifier Letter Acute Accent", '\''),
+    ('ˋ', "Modifier Letter Grave Accent", '\''),
+    ('˴', "Modifier Letter Middle Grave Accent", '\''),
+    ('ʻ', "Modifier Letter Turned Comma", '\''),
+    ('ʽ', "Modifier Letter Reversed Comma", '\''),
+    ('ʼ', "Modifier Letter Apostrophe", '\''),
+    ('ʾ', "Modifier Letter Right Half Ring", '\''),
+    ('ꞌ', "Latin Small Letter Saltillo", '\''),
+    ('י', "Hebrew Letter Yod", '\''),
+    ('ߴ', "Nko High Tone Apostrophe", '\''),
+    ('ߵ', "Nko Low Tone Apostrophe", '\''),
+    ('ᑊ', "Canadian Syllabics West-Cree P", '\''),
+    ('ᛌ', "Runic Letter Short-Twig-Sol S", '\''),
+    ('𖽑', "Miao Sign Aspiration", '\''),
+    ('𖽒', "Miao Sign Reformed Voicing", '\''),
+
+    ('᳓', "Vedic Sign Nihshvasa", '"'),
+    ('＂', "Fullwidth Quotation Mark", '"'),
+    ('“', "Left Double Quotation Mark", '"'),
+    ('”', "Right Double Quotation Mark", '"'),
+    ('‟', "Double High-Reversed-9 Quotation Mark", '"'),
+    ('″', "Double Prime", '"'),
+    ('‶', "Reversed Double Prime", '"'),
+    ('〃', "Ditto Mark", '"'),
+    ('״', "Hebrew Punctuation Gershayim", '"'),
+    ('˝', "Double Acute Accent", '"'),
+    ('ʺ', "Modifier Letter Double Prime", '"'),
+    ('˶', "Modifier Letter Middle Double Acute Accent", '"'),
+    ('˵', "Modifier Letter Middle Double Grave Accent", '"'),
+    ('ˮ', "Modifier Letter Double Apostrophe", '"'),
+    ('ײ', "Hebrew Ligature Yiddish Double Yod", '"'),
+    ('❞', "Heavy Double Comma Quotation Mark Ornament", '"'),
+    ('❝', "Heavy Double Turned Comma Quotation Mark Ornament", '"'),
+
+    ('（', "Fullwidth Left Parenthesis", '('),
+    ('❨', "Medium Left Parenthesis Ornament", '('),
+    ('﴾', "Ornate Left Parenthesis", '('),
+
+    ('）', "Fullwidth Right Parenthesis", ')'),
+    ('❩', "Medium Right Parenthesis Ornament", ')'),
+    ('﴿', "Ornate Right Parenthesis", ')'),
+
+    ('［', "Fullwidth Left Square Bracket", '['),
+    ('❲', "Light Left Tortoise Shell Bracket Ornament", '['),
+    ('「', "Left Corner Bracket", '['),
+    ('『', "Left White Corner Bracket", '['),
+    ('【', "Left Black Lenticular Bracket", '['),
+    ('〔', "Left Tortoise Shell Bracket", '['),
+    ('〖', "Left White Lenticular Bracket", '['),
+    ('〘', "Left White Tortoise Shell Bracket", '['),
+    ('〚', "Left White Square Bracket", '['),
+
+    ('］', "Fullwidth Right Square Bracket", ']'),
+    ('❳', "Light Right Tortoise Shell Bracket Ornament", ']'),
+    ('」', "Right Corner Bracket", ']'),
+    ('』', "Right White Corner Bracket", ']'),
+    ('】', "Right Black Lenticular Bracket", ']'),
+    ('〕', "Right Tortoise Shell Bracket", ']'),
+    ('〗', "Right White Lenticular Bracket", ']'),
+    ('〙', "Right White Tortoise Shell Bracket", ']'),
+    ('〛', "Right White Square Bracket", ']'),
+
+    ('❴', "Medium Left Curly Bracket Ornament", '{'),
+    ('𝄔', "Musical Symbol Brace", '{'),
+    ('｛', "Fullwidth Left Curly Bracket", '{'),
+
+    ('❵', "Medium Right Curly Bracket Ornament", '}'),
+    ('｝', "Fullwidth Right Curly Bracket", '}'),
+
+    ('⁎', "Low Asterisk", '*'),
+    ('٭', "Arabic Five Pointed Star", '*'),
+    ('∗', "Asterisk Operator", '*'),
+    ('𐌟', "Old Italic Letter Ess", '*'),
+    ('＊', "Fullwidth Asterisk", '*'),
+
+    ('᜵', "Philippine Single Punctuation", '/'),
+    ('⁁', "Caret Insertion Point", '/'),
+    ('∕', "Division Slash", '/'),
+    ('⁄', "Fraction Slash", '/'),
+    ('╱', "Box Drawings Light Diagonal Upper Right To Lower Left", '/'),
+    ('⟋', "Mathematical Rising Diagonal", '/'),
+    ('⧸', "Big Solidus", '/'),
+    ('𝈺', "Greek Instrumental Notation Symbol-47", '/'),
+    ('㇓', "CJK Stroke Sp", '/'),
+    ('〳', "Vertical Kana Repeat Mark Upper Half", '/'),
+    ('Ⳇ', "Coptic Capital Letter Old Coptic Esh", '/'),
+    ('ノ', "Katakana Letter No", '/'),
+    ('丿', "CJK Unified Ideograph-4E3F", '/'),
+    ('⼃', "Kangxi Radical Slash", '/'),
+    ('／', "Fullwidth Solidus", '/'),
+
+    ('＼', "Fullwidth Reverse Solidus", '\\'),
+    ('﹨', "Small Reverse Solidus", '\\'),
+    ('∖', "Set Minus", '\\'),
+    ('⟍', "Mathematical Falling Diagonal", '\\'),
+    ('⧵', "Reverse Solidus Operator", '\\'),
+    ('⧹', "Big Reverse Solidus", '\\'),
+    ('⧹', "Greek Vocal Notation Symbol-16", '\\'),
+    ('⧹', "Greek Instrumental Symbol-48", '\\'),
+    ('㇔', "CJK Stroke D", '\\'),
+    ('丶', "CJK Unified Ideograph-4E36", '\\'),
+    ('⼂', "Kangxi Radical Dot", '\\'),
+    ('、', "Ideographic Comma", '\\'),
+    ('ヽ', "Katakana Iteration Mark", '\\'),
+
+    ('ꝸ', "Latin Small Letter Um", '&'),
+    ('＆', "Fullwidth Ampersand", '&'),
+
+    ('᛭', "Runic Cross Punctuation", '+'),
+    ('➕', "Heavy Plus Sign", '+'),
+    ('𐊛', "Lycian Letter H", '+'),
+    ('﬩', "Hebrew Letter Alternative Plus Sign", '+'),
+    ('＋', "Fullwidth Plus Sign", '+'),
+
+    ('‹', "Single Left-Pointing Angle Quotation Mark", '<'),
+    ('❮', "Heavy Left-Pointing Angle Quotation Mark Ornament", '<'),
+    ('˂', "Modifier Letter Left Arrowhead", '<'),
+    ('𝈶', "Greek Instrumental Symbol-40", '<'),
+    ('ᐸ', "Canadian Syllabics Pa", '<'),
+    ('ᚲ', "Runic Letter Kauna", '<'),
+    ('❬', "Medium Left-Pointing Angle Bracket Ornament", '<'),
+    ('⟨', "Mathematical Left Angle Bracket", '<'),
+    ('〈', "Left-Pointing Angle Bracket", '<'),
+    ('〈', "Left Angle Bracket", '<'),
+    ('㇛', "CJK Stroke Pd", '<'),
+    ('く', "Hiragana Letter Ku", '<'),
+    ('𡿨', "CJK Unified Ideograph-21FE8", '<'),
+    ('《', "Left Double Angle Bracket", '<'),
+    ('＜', "Fullwidth Less-Than Sign", '<'),
+
+    ('᐀', "Canadian Syllabics Hyphen", '='),
+    ('⹀', "Double Hyphen", '='),
+    ('゠', "Katakana-Hiragana Double Hyphen", '='),
+    ('꓿', "Lisu Punctuation Full Stop", '='),
+    ('＝', "Fullwidth Equals Sign", '='),
+
+    ('›', "Single Right-Pointing Angle Quotation Mark", '>'),
+    ('❯', "Heavy Right-Pointing Angle Quotation Mark Ornament", '>'),
+    ('˃', "Modifier Letter Right Arrowhead", '>'),
+    ('𝈷', "Greek Instrumental Symbol-42", '>'),
+    ('ᐳ', "Canadian Syllabics Po", '>'),
+    ('𖼿', "Miao Letter Archaic Zza", '>'),
+    ('❭', "Medium Right-Pointing Angle Bracket Ornament", '>'),
+    ('⟩', "Mathematical Right Angle Bracket", '>'),
+    ('〉', "Right-Pointing Angle Bracket", '>'),
+    ('〉', "Right Angle Bracket", '>'),
+    ('》', "Right Double Angle Bracket", '>'),
+    ('＞', "Fullwidth Greater-Than Sign", '>'),
+];
+
+// FIXME: the lexer could be used to turn the ASCII version of unicode homoglyphs, instead of
+// keeping the substitution token in this table. Ideally, this should be inside `rustc_lexer`.
+// However, we should first remove compound tokens like `<<` from `rustc_lexer`, and then add
+// fancier error recovery to it, as there will be less overall work to do this way.
+const ASCII_ARRAY: &[(char, &str, Option<token::TokenKind>)] = &[
+    (' ', "Space", Some(token::Whitespace)),
+    ('_', "Underscore", Some(token::Ident(kw::Underscore, false))),
+    ('-', "Minus/Hyphen", Some(token::BinOp(token::Minus))),
+    (',', "Comma", Some(token::Comma)),
+    (';', "Semicolon", Some(token::Semi)),
+    (':', "Colon", Some(token::Colon)),
+    ('!', "Exclamation Mark", Some(token::Not)),
+    ('?', "Question Mark", Some(token::Question)),
+    ('.', "Period", Some(token::Dot)),
+    ('(', "Left Parenthesis", Some(token::OpenDelim(token::Paren))),
+    (')', "Right Parenthesis", Some(token::CloseDelim(token::Paren))),
+    ('[', "Left Square Bracket", Some(token::OpenDelim(token::Bracket))),
+    (']', "Right Square Bracket", Some(token::CloseDelim(token::Bracket))),
+    ('{', "Left Curly Brace", Some(token::OpenDelim(token::Brace))),
+    ('}', "Right Curly Brace", Some(token::CloseDelim(token::Brace))),
+    ('*', "Asterisk", Some(token::BinOp(token::Star))),
+    ('/', "Slash", Some(token::BinOp(token::Slash))),
+    ('\\', "Backslash", None),
+    ('&', "Ampersand", Some(token::BinOp(token::And))),
+    ('+', "Plus Sign", Some(token::BinOp(token::Plus))),
+    ('<', "Less-Than Sign", Some(token::Lt)),
+    ('=', "Equals Sign", Some(token::Eq)),
+    ('>', "Greater-Than Sign", Some(token::Gt)),
+    // FIXME: Literals are already lexed by this point, so we can't recover gracefully just by
+    // spitting the correct token out.
+    ('\'', "Single Quote", None),
+    ('"', "Quotation Mark", None),
+];
+
+crate fn check_for_substitution<'a>(
+    reader: &StringReader<'a>,
+    pos: BytePos,
+    ch: char,
+    err: &mut DiagnosticBuilder<'a>,
+) -> Option<token::TokenKind> {
+    let (u_name, ascii_char) = match UNICODE_ARRAY.iter().find(|&&(c, _, _)| c == ch) {
+        Some(&(_u_char, u_name, ascii_char)) => (u_name, ascii_char),
+        None => return None,
+    };
+
+    let span = Span::with_root_ctxt(pos, pos + Pos::from_usize(ch.len_utf8()));
+
+    let (ascii_name, token) = match ASCII_ARRAY.iter().find(|&&(c, _, _)| c == ascii_char) {
+        Some((_ascii_char, ascii_name, token)) => (ascii_name, token),
+        None => {
+            let msg = format!("substitution character not found for '{}'", ch);
+            reader.sess.span_diagnostic.span_bug_no_panic(span, &msg);
+            return None;
+        }
+    };
+
+    // special help suggestion for "directed" double quotes
+    if let Some(s) = peek_delimited(&reader.src[reader.src_index(pos)..], '“', '”') {
+        let msg = format!(
+            "Unicode characters '“' (Left Double Quotation Mark) and \
+             '”' (Right Double Quotation Mark) look like '{}' ({}), but are not",
+            ascii_char, ascii_name
+        );
+        err.span_suggestion(
+            Span::with_root_ctxt(
+                pos,
+                pos + Pos::from_usize('“'.len_utf8() + s.len() + '”'.len_utf8()),
+            ),
+            &msg,
+            format!("\"{}\"", s),
+            Applicability::MaybeIncorrect,
+        );
+    } else {
+        let msg = format!(
+            "Unicode character '{}' ({}) looks like '{}' ({}), but it is not",
+            ch, u_name, ascii_char, ascii_name
+        );
+        err.span_suggestion(span, &msg, ascii_char.to_string(), Applicability::MaybeIncorrect);
+    }
+    token.clone()
+}
+
+/// Extract string if found at current position with given delimiters
+fn peek_delimited(text: &str, from_ch: char, to_ch: char) -> Option<&str> {
+    let mut chars = text.chars();
+    let first_char = chars.next()?;
+    if first_char != from_ch {
+        return None;
+    }
+    let last_char_idx = chars.as_str().find(to_ch)?;
+    Some(&chars.as_str()[..last_char_idx])
+}
diff --git a/src/librustc_parse/lib.rs b/src/librustc_parse/lib.rs
new file mode 100644
index 00000000000..9f507d5319e
--- /dev/null
+++ b/src/librustc_parse/lib.rs
@@ -0,0 +1,423 @@
+//! The main parser interface.
+
+#![feature(crate_visibility_modifier)]
+
+use syntax::ast;
+use syntax::print::pprust;
+use syntax::sess::ParseSess;
+use syntax::token::{self, Nonterminal};
+use syntax::tokenstream::{self, TokenStream, TokenTree};
+
+use errors::{PResult, FatalError, Level, Diagnostic};
+use rustc_data_structures::sync::Lrc;
+use syntax_pos::{Span, SourceFile, FileName};
+
+use std::borrow::Cow;
+use std::path::Path;
+use std::str;
+
+use log::info;
+
+pub const MACRO_ARGUMENTS: Option<&'static str> = Some("macro arguments");
+
+#[macro_use]
+pub mod parser;
+use parser::{Parser, emit_unclosed_delims, make_unclosed_delims_error};
+pub mod lexer;
+pub mod validate_attr;
+pub mod error_codes;
+
+#[derive(Clone)]
+pub struct Directory<'a> {
+    pub path: Cow<'a, Path>,
+    pub ownership: DirectoryOwnership,
+}
+
+#[derive(Copy, Clone)]
+pub enum DirectoryOwnership {
+    Owned {
+        // None if `mod.rs`, `Some("foo")` if we're in `foo.rs`.
+        relative: Option<ast::Ident>,
+    },
+    UnownedViaBlock,
+    UnownedViaMod,
+}
+
+// A bunch of utility functions of the form `parse_<thing>_from_<source>`
+// where <thing> includes crate, expr, item, stmt, tts, and one that
+// uses a HOF to parse anything, and <source> includes file and
+// `source_str`.
+
+/// A variant of 'panictry!' that works on a Vec<Diagnostic> instead of a single DiagnosticBuilder.
+macro_rules! panictry_buffer {
+    ($handler:expr, $e:expr) => ({
+        use std::result::Result::{Ok, Err};
+        use errors::FatalError;
+        match $e {
+            Ok(e) => e,
+            Err(errs) => {
+                for e in errs {
+                    $handler.emit_diagnostic(&e);
+                }
+                FatalError.raise()
+            }
+        }
+    })
+}
+
+pub fn parse_crate_from_file<'a>(input: &Path, sess: &'a ParseSess) -> PResult<'a, ast::Crate> {
+    let mut parser = new_parser_from_file(sess, input);
+    parser.parse_crate_mod()
+}
+
+pub fn parse_crate_attrs_from_file<'a>(input: &Path, sess: &'a ParseSess)
+                                       -> PResult<'a, Vec<ast::Attribute>> {
+    let mut parser = new_parser_from_file(sess, input);
+    parser.parse_inner_attributes()
+}
+
+pub fn parse_crate_from_source_str(name: FileName, source: String, sess: &ParseSess)
+                                       -> PResult<'_, ast::Crate> {
+    new_parser_from_source_str(sess, name, source).parse_crate_mod()
+}
+
+pub fn parse_crate_attrs_from_source_str(name: FileName, source: String, sess: &ParseSess)
+                                             -> PResult<'_, Vec<ast::Attribute>> {
+    new_parser_from_source_str(sess, name, source).parse_inner_attributes()
+}
+
+pub fn parse_stream_from_source_str(
+    name: FileName,
+    source: String,
+    sess: &ParseSess,
+    override_span: Option<Span>,
+) -> TokenStream {
+    let (stream, mut errors) = source_file_to_stream(
+        sess,
+        sess.source_map().new_source_file(name, source),
+        override_span,
+    );
+    emit_unclosed_delims(&mut errors, &sess);
+    stream
+}
+
+/// Creates a new parser from a source string.
+pub fn new_parser_from_source_str(sess: &ParseSess, name: FileName, source: String) -> Parser<'_> {
+    panictry_buffer!(&sess.span_diagnostic, maybe_new_parser_from_source_str(sess, name, source))
+}
+
+/// Creates a new parser from a source string. Returns any buffered errors from lexing the initial
+/// token stream.
+pub fn maybe_new_parser_from_source_str(sess: &ParseSess, name: FileName, source: String)
+    -> Result<Parser<'_>, Vec<Diagnostic>>
+{
+    let mut parser = maybe_source_file_to_parser(sess,
+                                                 sess.source_map().new_source_file(name, source))?;
+    parser.recurse_into_file_modules = false;
+    Ok(parser)
+}
+
+/// Creates a new parser, handling errors as appropriate if the file doesn't exist.
+pub fn new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path) -> Parser<'a> {
+    source_file_to_parser(sess, file_to_source_file(sess, path, None))
+}
+
+/// Creates a new parser, returning buffered diagnostics if the file doesn't exist,
+/// or from lexing the initial token stream.
+pub fn maybe_new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path)
+    -> Result<Parser<'a>, Vec<Diagnostic>> {
+    let file = try_file_to_source_file(sess, path, None).map_err(|db| vec![db])?;
+    maybe_source_file_to_parser(sess, file)
+}
+
+/// Given a session, a crate config, a path, and a span, add
+/// the file at the given path to the `source_map`, and returns a parser.
+/// On an error, uses the given span as the source of the problem.
+pub fn new_sub_parser_from_file<'a>(sess: &'a ParseSess,
+                                    path: &Path,
+                                    directory_ownership: DirectoryOwnership,
+                                    module_name: Option<String>,
+                                    sp: Span) -> Parser<'a> {
+    let mut p = source_file_to_parser(sess, file_to_source_file(sess, path, Some(sp)));
+    p.directory.ownership = directory_ownership;
+    p.root_module_name = module_name;
+    p
+}
+
+/// Given a `source_file` and config, returns a parser.
+fn source_file_to_parser(sess: &ParseSess, source_file: Lrc<SourceFile>) -> Parser<'_> {
+    panictry_buffer!(&sess.span_diagnostic,
+                     maybe_source_file_to_parser(sess, source_file))
+}
+
+/// Given a `source_file` and config, return a parser. Returns any buffered errors from lexing the
+/// initial token stream.
+fn maybe_source_file_to_parser(
+    sess: &ParseSess,
+    source_file: Lrc<SourceFile>,
+) -> Result<Parser<'_>, Vec<Diagnostic>> {
+    let end_pos = source_file.end_pos;
+    let (stream, unclosed_delims) = maybe_file_to_stream(sess, source_file, None)?;
+    let mut parser = stream_to_parser(sess, stream, None);
+    parser.unclosed_delims = unclosed_delims;
+    if parser.token == token::Eof && parser.token.span.is_dummy() {
+        parser.token.span = Span::new(end_pos, end_pos, parser.token.span.ctxt());
+    }
+
+    Ok(parser)
+}
+
+// Must preserve old name for now, because `quote!` from the *existing*
+// compiler expands into it.
+pub fn new_parser_from_tts(sess: &ParseSess, tts: Vec<TokenTree>) -> Parser<'_> {
+    stream_to_parser(sess, tts.into_iter().collect(), crate::MACRO_ARGUMENTS)
+}
+
+
+// Base abstractions
+
+/// Given a session and a path and an optional span (for error reporting),
+/// add the path to the session's source_map and return the new source_file or
+/// error when a file can't be read.
+fn try_file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>)
+                   -> Result<Lrc<SourceFile>, Diagnostic> {
+    sess.source_map().load_file(path)
+    .map_err(|e| {
+        let msg = format!("couldn't read {}: {}", path.display(), e);
+        let mut diag = Diagnostic::new(Level::Fatal, &msg);
+        if let Some(sp) = spanopt {
+            diag.set_span(sp);
+        }
+        diag
+    })
+}
+
+/// Given a session and a path and an optional span (for error reporting),
+/// adds the path to the session's `source_map` and returns the new `source_file`.
+fn file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>)
+                   -> Lrc<SourceFile> {
+    match try_file_to_source_file(sess, path, spanopt) {
+        Ok(source_file) => source_file,
+        Err(d) => {
+            sess.span_diagnostic.emit_diagnostic(&d);
+            FatalError.raise();
+        }
+    }
+}
+
+/// Given a `source_file`, produces a sequence of token trees.
+pub fn source_file_to_stream(
+    sess: &ParseSess,
+    source_file: Lrc<SourceFile>,
+    override_span: Option<Span>,
+) -> (TokenStream, Vec<lexer::UnmatchedBrace>) {
+    panictry_buffer!(&sess.span_diagnostic, maybe_file_to_stream(sess, source_file, override_span))
+}
+
+/// Given a source file, produces a sequence of token trees. Returns any buffered errors from
+/// parsing the token stream.
+pub fn maybe_file_to_stream(
+    sess: &ParseSess,
+    source_file: Lrc<SourceFile>,
+    override_span: Option<Span>,
+) -> Result<(TokenStream, Vec<lexer::UnmatchedBrace>), Vec<Diagnostic>> {
+    let srdr = lexer::StringReader::new(sess, source_file, override_span);
+    let (token_trees, unmatched_braces) = srdr.into_token_trees();
+
+    match token_trees {
+        Ok(stream) => Ok((stream, unmatched_braces)),
+        Err(err) => {
+            let mut buffer = Vec::with_capacity(1);
+            err.buffer(&mut buffer);
+            // Not using `emit_unclosed_delims` to use `db.buffer`
+            for unmatched in unmatched_braces {
+                if let Some(err) = make_unclosed_delims_error(unmatched, &sess) {
+                    err.buffer(&mut buffer);
+                }
+            }
+            Err(buffer)
+        }
+    }
+}
+
+/// Given a stream and the `ParseSess`, produces a parser.
+pub fn stream_to_parser<'a>(
+    sess: &'a ParseSess,
+    stream: TokenStream,
+    subparser_name: Option<&'static str>,
+) -> Parser<'a> {
+    Parser::new(sess, stream, None, true, false, subparser_name)
+}
+
+/// Given a stream, the `ParseSess` and the base directory, produces a parser.
+///
+/// Use this function when you are creating a parser from the token stream
+/// and also care about the current working directory of the parser (e.g.,
+/// you are trying to resolve modules defined inside a macro invocation).
+///
+/// # Note
+///
+/// The main usage of this function is outside of rustc, for those who uses
+/// libsyntax as a library. Please do not remove this function while refactoring
+/// just because it is not used in rustc codebase!
+pub fn stream_to_parser_with_base_dir<'a>(
+    sess: &'a ParseSess,
+    stream: TokenStream,
+    base_dir: Directory<'a>,
+) -> Parser<'a> {
+    Parser::new(sess, stream, Some(base_dir), true, false, None)
+}
+
+/// Runs the given subparser `f` on the tokens of the given `attr`'s item.
+pub fn parse_in_attr<'a, T>(
+    sess: &'a ParseSess,
+    attr: &ast::Attribute,
+    mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
+) -> PResult<'a, T> {
+    let mut parser = Parser::new(
+        sess,
+        attr.get_normal_item().tokens.clone(),
+        None,
+        false,
+        false,
+        Some("attribute"),
+    );
+    let result = f(&mut parser)?;
+    if parser.token != token::Eof {
+        parser.unexpected()?;
+    }
+    Ok(result)
+}
+
+// NOTE(Centril): The following probably shouldn't be here but it acknowledges the
+// fact that architecturally, we are using parsing (read on below to understand why).
+
+pub fn nt_to_tokenstream(nt: &Nonterminal, sess: &ParseSess, span: Span) -> TokenStream {
+    // A `Nonterminal` is often a parsed AST item. At this point we now
+    // need to convert the parsed AST to an actual token stream, e.g.
+    // un-parse it basically.
+    //
+    // Unfortunately there's not really a great way to do that in a
+    // guaranteed lossless fashion right now. The fallback here is to just
+    // stringify the AST node and reparse it, but this loses all span
+    // information.
+    //
+    // As a result, some AST nodes are annotated with the token stream they
+    // came from. Here we attempt to extract these lossless token streams
+    // before we fall back to the stringification.
+    let tokens = match *nt {
+        Nonterminal::NtItem(ref item) => {
+            prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span)
+        }
+        Nonterminal::NtTraitItem(ref item) => {
+            prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span)
+        }
+        Nonterminal::NtImplItem(ref item) => {
+            prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span)
+        }
+        Nonterminal::NtIdent(ident, is_raw) => {
+            Some(tokenstream::TokenTree::token(token::Ident(ident.name, is_raw), ident.span).into())
+        }
+        Nonterminal::NtLifetime(ident) => {
+            Some(tokenstream::TokenTree::token(token::Lifetime(ident.name), ident.span).into())
+        }
+        Nonterminal::NtTT(ref tt) => {
+            Some(tt.clone().into())
+        }
+        _ => None,
+    };
+
+    // FIXME(#43081): Avoid this pretty-print + reparse hack
+    let source = pprust::nonterminal_to_string(nt);
+    let filename = FileName::macro_expansion_source_code(&source);
+    let tokens_for_real = parse_stream_from_source_str(filename, source, sess, Some(span));
+
+    // During early phases of the compiler the AST could get modified
+    // directly (e.g., attributes added or removed) and the internal cache
+    // of tokens my not be invalidated or updated. Consequently if the
+    // "lossless" token stream disagrees with our actual stringification
+    // (which has historically been much more battle-tested) then we go
+    // with the lossy stream anyway (losing span information).
+    //
+    // Note that the comparison isn't `==` here to avoid comparing spans,
+    // but it *also* is a "probable" equality which is a pretty weird
+    // definition. We mostly want to catch actual changes to the AST
+    // like a `#[cfg]` being processed or some weird `macro_rules!`
+    // expansion.
+    //
+    // What we *don't* want to catch is the fact that a user-defined
+    // literal like `0xf` is stringified as `15`, causing the cached token
+    // stream to not be literal `==` token-wise (ignoring spans) to the
+    // token stream we got from stringification.
+    //
+    // Instead the "probably equal" check here is "does each token
+    // recursively have the same discriminant?" We basically don't look at
+    // the token values here and assume that such fine grained token stream
+    // modifications, including adding/removing typically non-semantic
+    // tokens such as extra braces and commas, don't happen.
+    if let Some(tokens) = tokens {
+        if tokens.probably_equal_for_proc_macro(&tokens_for_real) {
+            return tokens
+        }
+        info!("cached tokens found, but they're not \"probably equal\", \
+                going with stringified version");
+    }
+    return tokens_for_real
+}
+
+fn prepend_attrs(
+    sess: &ParseSess,
+    attrs: &[ast::Attribute],
+    tokens: Option<&tokenstream::TokenStream>,
+    span: syntax_pos::Span
+) -> Option<tokenstream::TokenStream> {
+    let tokens = tokens?;
+    if attrs.len() == 0 {
+        return Some(tokens.clone())
+    }
+    let mut builder = tokenstream::TokenStreamBuilder::new();
+    for attr in attrs {
+        assert_eq!(attr.style, ast::AttrStyle::Outer,
+                   "inner attributes should prevent cached tokens from existing");
+
+        let source = pprust::attribute_to_string(attr);
+        let macro_filename = FileName::macro_expansion_source_code(&source);
+
+        let item = match attr.kind {
+            ast::AttrKind::Normal(ref item) => item,
+            ast::AttrKind::DocComment(_) => {
+                let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span));
+                builder.push(stream);
+                continue
+            }
+        };
+
+        // synthesize # [ $path $tokens ] manually here
+        let mut brackets = tokenstream::TokenStreamBuilder::new();
+
+        // For simple paths, push the identifier directly
+        if item.path.segments.len() == 1 && item.path.segments[0].args.is_none() {
+            let ident = item.path.segments[0].ident;
+            let token = token::Ident(ident.name, ident.as_str().starts_with("r#"));
+            brackets.push(tokenstream::TokenTree::token(token, ident.span));
+
+        // ... and for more complicated paths, fall back to a reparse hack that
+        // should eventually be removed.
+        } else {
+            let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span));
+            brackets.push(stream);
+        }
+
+        brackets.push(item.tokens.clone());
+
+        // The span we list here for `#` and for `[ ... ]` are both wrong in
+        // that it encompasses more than each token, but it hopefully is "good
+        // enough" for now at least.
+        builder.push(tokenstream::TokenTree::token(token::Pound, attr.span));
+        let delim_span = tokenstream::DelimSpan::from_single(attr.span);
+        builder.push(tokenstream::TokenTree::Delimited(
+            delim_span, token::DelimToken::Bracket, brackets.build().into()));
+    }
+    builder.push(tokens.clone());
+    Some(builder.build())
+}
diff --git a/src/librustc_parse/parser/attr.rs b/src/librustc_parse/parser/attr.rs
new file mode 100644
index 00000000000..524b551e54c
--- /dev/null
+++ b/src/librustc_parse/parser/attr.rs
@@ -0,0 +1,351 @@
+use super::{SeqSep, Parser, TokenType, PathStyle};
+use syntax::attr;
+use syntax::ast;
+use syntax::util::comments;
+use syntax::token::{self, Nonterminal, DelimToken};
+use syntax::tokenstream::{TokenStream, TokenTree};
+use syntax_pos::{Span, Symbol};
+use errors::PResult;
+
+use log::debug;
+
+#[derive(Debug)]
+enum InnerAttributeParsePolicy<'a> {
+    Permitted,
+    NotPermitted { reason: &'a str, saw_doc_comment: bool, prev_attr_sp: Option<Span> },
+}
+
+const DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG: &str = "an inner attribute is not \
+                                                     permitted in this context";
+
+impl<'a> Parser<'a> {
+    /// Parses attributes that appear before an item.
+    pub(super) fn parse_outer_attributes(&mut self) -> PResult<'a, Vec<ast::Attribute>> {
+        let mut attrs: Vec<ast::Attribute> = Vec::new();
+        let mut just_parsed_doc_comment = false;
+        loop {
+            debug!("parse_outer_attributes: self.token={:?}", self.token);
+            match self.token.kind {
+                token::Pound => {
+                    let inner_error_reason = if just_parsed_doc_comment {
+                        "an inner attribute is not permitted following an outer doc comment"
+                    } else if !attrs.is_empty() {
+                        "an inner attribute is not permitted following an outer attribute"
+                    } else {
+                        DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG
+                    };
+                    let inner_parse_policy =
+                        InnerAttributeParsePolicy::NotPermitted {
+                            reason: inner_error_reason,
+                            saw_doc_comment: just_parsed_doc_comment,
+                            prev_attr_sp: attrs.last().and_then(|a| Some(a.span))
+                        };
+                    let attr = self.parse_attribute_with_inner_parse_policy(inner_parse_policy)?;
+                    attrs.push(attr);
+                    just_parsed_doc_comment = false;
+                }
+                token::DocComment(s) => {
+                    let attr = self.mk_doc_comment(s);
+                    if attr.style != ast::AttrStyle::Outer {
+                        let mut err = self.fatal("expected outer doc comment");
+                        err.note("inner doc comments like this (starting with \
+                                  `//!` or `/*!`) can only appear before items");
+                        return Err(err);
+                    }
+                    attrs.push(attr);
+                    self.bump();
+                    just_parsed_doc_comment = true;
+                }
+                _ => break,
+            }
+        }
+        Ok(attrs)
+    }
+
+    fn mk_doc_comment(&self, s: Symbol) -> ast::Attribute {
+        let style = comments::doc_comment_style(&s.as_str());
+        attr::mk_doc_comment(style, s, self.token.span)
+    }
+
+    /// Matches `attribute = # ! [ meta_item ]`.
+    ///
+    /// If `permit_inner` is `true`, then a leading `!` indicates an inner
+    /// attribute.
+    pub fn parse_attribute(&mut self, permit_inner: bool) -> PResult<'a, ast::Attribute> {
+        debug!("parse_attribute: permit_inner={:?} self.token={:?}",
+               permit_inner,
+               self.token);
+        let inner_parse_policy = if permit_inner {
+            InnerAttributeParsePolicy::Permitted
+        } else {
+            InnerAttributeParsePolicy::NotPermitted {
+                reason: DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG,
+                saw_doc_comment: false,
+                prev_attr_sp: None
+            }
+        };
+        self.parse_attribute_with_inner_parse_policy(inner_parse_policy)
+    }
+
+    /// The same as `parse_attribute`, except it takes in an `InnerAttributeParsePolicy`
+    /// that prescribes how to handle inner attributes.
+    fn parse_attribute_with_inner_parse_policy(
+        &mut self,
+        inner_parse_policy: InnerAttributeParsePolicy<'_>
+    ) -> PResult<'a, ast::Attribute> {
+        debug!("parse_attribute_with_inner_parse_policy: inner_parse_policy={:?} self.token={:?}",
+               inner_parse_policy,
+               self.token);
+        let (span, item, style) = match self.token.kind {
+            token::Pound => {
+                let lo = self.token.span;
+                self.bump();
+
+                if let InnerAttributeParsePolicy::Permitted = inner_parse_policy {
+                    self.expected_tokens.push(TokenType::Token(token::Not));
+                }
+
+                let style = if self.token == token::Not {
+                    self.bump();
+                    ast::AttrStyle::Inner
+                } else {
+                    ast::AttrStyle::Outer
+                };
+
+                self.expect(&token::OpenDelim(token::Bracket))?;
+                let item = self.parse_attr_item()?;
+                self.expect(&token::CloseDelim(token::Bracket))?;
+                let hi = self.prev_span;
+
+                let attr_sp = lo.to(hi);
+
+                // Emit error if inner attribute is encountered and not permitted
+                if style == ast::AttrStyle::Inner {
+                    if let InnerAttributeParsePolicy::NotPermitted { reason,
+                        saw_doc_comment, prev_attr_sp } = inner_parse_policy {
+                        let prev_attr_note = if saw_doc_comment {
+                            "previous doc comment"
+                        } else {
+                            "previous outer attribute"
+                        };
+
+                        let mut diagnostic = self
+                            .diagnostic()
+                            .struct_span_err(attr_sp, reason);
+
+                        if let Some(prev_attr_sp) = prev_attr_sp {
+                            diagnostic
+                                .span_label(attr_sp, "not permitted following an outer attibute")
+                                .span_label(prev_attr_sp, prev_attr_note);
+                        }
+
+                        diagnostic
+                            .note("inner attributes, like `#![no_std]`, annotate the item \
+                                   enclosing them, and are usually found at the beginning of \
+                                   source files. Outer attributes, like `#[test]`, annotate the \
+                                   item following them.")
+                            .emit()
+                    }
+                }
+
+                (attr_sp, item, style)
+            }
+            _ => {
+                let token_str = self.this_token_to_string();
+                return Err(self.fatal(&format!("expected `#`, found `{}`", token_str)));
+            }
+        };
+
+        Ok(attr::mk_attr_from_item(style, item, span))
+    }
+
+    /// Parses an inner part of an attribute (the path and following tokens).
+    /// The tokens must be either a delimited token stream, or empty token stream,
+    /// or the "legacy" key-value form.
+    ///     PATH `(` TOKEN_STREAM `)`
+    ///     PATH `[` TOKEN_STREAM `]`
+    ///     PATH `{` TOKEN_STREAM `}`
+    ///     PATH
+    ///     PATH `=` UNSUFFIXED_LIT
+    /// The delimiters or `=` are still put into the resulting token stream.
+    pub fn parse_attr_item(&mut self) -> PResult<'a, ast::AttrItem> {
+        let item = match self.token.kind {
+            token::Interpolated(ref nt) => match **nt {
+                Nonterminal::NtMeta(ref item) => Some(item.clone()),
+                _ => None,
+            },
+            _ => None,
+        };
+        Ok(if let Some(item) = item {
+            self.bump();
+            item
+        } else {
+            let path = self.parse_path(PathStyle::Mod)?;
+            let tokens = if self.check(&token::OpenDelim(DelimToken::Paren)) ||
+               self.check(&token::OpenDelim(DelimToken::Bracket)) ||
+               self.check(&token::OpenDelim(DelimToken::Brace)) {
+                   self.parse_token_tree().into()
+            } else if self.eat(&token::Eq) {
+                let eq = TokenTree::token(token::Eq, self.prev_span);
+                let mut is_interpolated_expr = false;
+                if let token::Interpolated(nt) = &self.token.kind {
+                    if let token::NtExpr(..) = **nt {
+                        is_interpolated_expr = true;
+                    }
+                }
+                let token_tree = if is_interpolated_expr {
+                    // We need to accept arbitrary interpolated expressions to continue
+                    // supporting things like `doc = $expr` that work on stable.
+                    // Non-literal interpolated expressions are rejected after expansion.
+                    self.parse_token_tree()
+                } else {
+                    self.parse_unsuffixed_lit()?.token_tree()
+                };
+                TokenStream::new(vec![eq.into(), token_tree.into()])
+            } else {
+                TokenStream::default()
+            };
+            ast::AttrItem { path, tokens }
+        })
+    }
+
+    /// Parses attributes that appear after the opening of an item. These should
+    /// be preceded by an exclamation mark, but we accept and warn about one
+    /// terminated by a semicolon.
+    ///
+    /// Matches `inner_attrs*`.
+    crate fn parse_inner_attributes(&mut self) -> PResult<'a, Vec<ast::Attribute>> {
+        let mut attrs: Vec<ast::Attribute> = vec![];
+        loop {
+            match self.token.kind {
+                token::Pound => {
+                    // Don't even try to parse if it's not an inner attribute.
+                    if !self.look_ahead(1, |t| t == &token::Not) {
+                        break;
+                    }
+
+                    let attr = self.parse_attribute(true)?;
+                    assert_eq!(attr.style, ast::AttrStyle::Inner);
+                    attrs.push(attr);
+                }
+                token::DocComment(s) => {
+                    // We need to get the position of this token before we bump.
+                    let attr = self.mk_doc_comment(s);
+                    if attr.style == ast::AttrStyle::Inner {
+                        attrs.push(attr);
+                        self.bump();
+                    } else {
+                        break;
+                    }
+                }
+                _ => break,
+            }
+        }
+        Ok(attrs)
+    }
+
+    fn parse_unsuffixed_lit(&mut self) -> PResult<'a, ast::Lit> {
+        let lit = self.parse_lit()?;
+        debug!("checking if {:?} is unusuffixed", lit);
+
+        if !lit.kind.is_unsuffixed() {
+            let msg = "suffixed literals are not allowed in attributes";
+            self.diagnostic().struct_span_err(lit.span, msg)
+                             .help("instead of using a suffixed literal \
+                                    (1u8, 1.0f32, etc.), use an unsuffixed version \
+                                    (1, 1.0, etc.).")
+                             .emit()
+        }
+
+        Ok(lit)
+    }
+
+    /// Parses `cfg_attr(pred, attr_item_list)` where `attr_item_list` is comma-delimited.
+    pub fn parse_cfg_attr(&mut self) -> PResult<'a, (ast::MetaItem, Vec<(ast::AttrItem, Span)>)> {
+        self.expect(&token::OpenDelim(token::Paren))?;
+
+        let cfg_predicate = self.parse_meta_item()?;
+        self.expect(&token::Comma)?;
+
+        // Presumably, the majority of the time there will only be one attr.
+        let mut expanded_attrs = Vec::with_capacity(1);
+
+        while !self.check(&token::CloseDelim(token::Paren)) {
+            let lo = self.token.span.lo();
+            let item = self.parse_attr_item()?;
+            expanded_attrs.push((item, self.prev_span.with_lo(lo)));
+            self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Paren)])?;
+        }
+
+        self.expect(&token::CloseDelim(token::Paren))?;
+        Ok((cfg_predicate, expanded_attrs))
+    }
+
+    /// Matches the following grammar (per RFC 1559).
+    ///
+    ///     meta_item : PATH ( '=' UNSUFFIXED_LIT | '(' meta_item_inner? ')' )? ;
+    ///     meta_item_inner : (meta_item | UNSUFFIXED_LIT) (',' meta_item_inner)? ;
+    pub fn parse_meta_item(&mut self) -> PResult<'a, ast::MetaItem> {
+        let nt_meta = match self.token.kind {
+            token::Interpolated(ref nt) => match **nt {
+                token::NtMeta(ref e) => Some(e.clone()),
+                _ => None,
+            },
+            _ => None,
+        };
+
+        if let Some(item) = nt_meta {
+            return match item.meta(item.path.span) {
+                Some(meta) => {
+                    self.bump();
+                    Ok(meta)
+                }
+                None => self.unexpected(),
+            }
+        }
+
+        let lo = self.token.span;
+        let path = self.parse_path(PathStyle::Mod)?;
+        let kind = self.parse_meta_item_kind()?;
+        let span = lo.to(self.prev_span);
+        Ok(ast::MetaItem { path, kind, span })
+    }
+
+    crate fn parse_meta_item_kind(&mut self) -> PResult<'a, ast::MetaItemKind> {
+        Ok(if self.eat(&token::Eq) {
+            ast::MetaItemKind::NameValue(self.parse_unsuffixed_lit()?)
+        } else if self.eat(&token::OpenDelim(token::Paren)) {
+            ast::MetaItemKind::List(self.parse_meta_seq()?)
+        } else {
+            ast::MetaItemKind::Word
+        })
+    }
+
+    /// Matches `meta_item_inner : (meta_item | UNSUFFIXED_LIT) ;`.
+    fn parse_meta_item_inner(&mut self) -> PResult<'a, ast::NestedMetaItem> {
+        match self.parse_unsuffixed_lit() {
+            Ok(lit) => {
+                return Ok(ast::NestedMetaItem::Literal(lit))
+            }
+            Err(ref mut err) => err.cancel(),
+        }
+
+        match self.parse_meta_item() {
+            Ok(mi) => {
+                return Ok(ast::NestedMetaItem::MetaItem(mi))
+            }
+            Err(ref mut err) => err.cancel(),
+        }
+
+        let found = self.this_token_to_string();
+        let msg = format!("expected unsuffixed literal or identifier, found `{}`", found);
+        Err(self.diagnostic().struct_span_err(self.token.span, &msg))
+    }
+
+    /// Matches `meta_seq = ( COMMASEP(meta_item_inner) )`.
+    fn parse_meta_seq(&mut self) -> PResult<'a, Vec<ast::NestedMetaItem>> {
+        self.parse_seq_to_end(&token::CloseDelim(token::Paren),
+                              SeqSep::trailing_allowed(token::Comma),
+                              |p: &mut Parser<'a>| p.parse_meta_item_inner())
+    }
+}
diff --git a/src/librustc_parse/parser/diagnostics.rs b/src/librustc_parse/parser/diagnostics.rs
new file mode 100644
index 00000000000..38eae008537
--- /dev/null
+++ b/src/librustc_parse/parser/diagnostics.rs
@@ -0,0 +1,1549 @@
+use super::{BlockMode, PathStyle, SemiColonMode, TokenType, TokenExpectType, SeqSep, Parser};
+
+use syntax::ast::{
+    self, Param, BinOpKind, BindingMode, BlockCheckMode, Expr, ExprKind, Ident, Item, ItemKind,
+    Mutability, Pat, PatKind, PathSegment, QSelf, Ty, TyKind,
+};
+use syntax::token::{self, TokenKind, token_can_begin_expr};
+use syntax::print::pprust;
+use syntax::ptr::P;
+use syntax::symbol::{kw, sym};
+use syntax::ThinVec;
+use syntax::util::parser::AssocOp;
+use syntax::struct_span_err;
+
+use errors::{PResult, Applicability, DiagnosticBuilder, DiagnosticId, pluralize};
+use rustc_data_structures::fx::FxHashSet;
+use syntax_pos::{Span, DUMMY_SP, MultiSpan, SpanSnippetError};
+use log::{debug, trace};
+use std::mem;
+
+const TURBOFISH: &'static str = "use `::<...>` instead of `<...>` to specify type arguments";
+
+/// Creates a placeholder argument.
+pub(super) fn dummy_arg(ident: Ident) -> Param {
+    let pat = P(Pat {
+        id: ast::DUMMY_NODE_ID,
+        kind: PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), ident, None),
+        span: ident.span,
+    });
+    let ty = Ty {
+        kind: TyKind::Err,
+        span: ident.span,
+        id: ast::DUMMY_NODE_ID
+    };
+    Param {
+        attrs: ThinVec::default(),
+        id: ast::DUMMY_NODE_ID,
+        pat,
+        span: ident.span,
+        ty: P(ty),
+        is_placeholder: false,
+    }
+}
+
+pub enum Error {
+    FileNotFoundForModule {
+        mod_name: String,
+        default_path: String,
+        secondary_path: String,
+        dir_path: String,
+    },
+    DuplicatePaths {
+        mod_name: String,
+        default_path: String,
+        secondary_path: String,
+    },
+    UselessDocComment,
+    InclusiveRangeWithNoEnd,
+}
+
+impl Error {
+    fn span_err<S: Into<MultiSpan>>(
+        self,
+        sp: S,
+        handler: &errors::Handler,
+    ) -> DiagnosticBuilder<'_> {
+        match self {
+            Error::FileNotFoundForModule {
+                ref mod_name,
+                ref default_path,
+                ref secondary_path,
+                ref dir_path,
+            } => {
+                let mut err = struct_span_err!(
+                    handler,
+                    sp,
+                    E0583,
+                    "file not found for module `{}`",
+                    mod_name,
+                );
+                err.help(&format!(
+                    "name the file either {} or {} inside the directory \"{}\"",
+                    default_path,
+                    secondary_path,
+                    dir_path,
+                ));
+                err
+            }
+            Error::DuplicatePaths { ref mod_name, ref default_path, ref secondary_path } => {
+                let mut err = struct_span_err!(
+                    handler,
+                    sp,
+                    E0584,
+                    "file for module `{}` found at both {} and {}",
+                    mod_name,
+                    default_path,
+                    secondary_path,
+                );
+                err.help("delete or rename one of them to remove the ambiguity");
+                err
+            }
+            Error::UselessDocComment => {
+                let mut err = struct_span_err!(
+                    handler,
+                    sp,
+                    E0585,
+                    "found a documentation comment that doesn't document anything",
+                );
+                err.help("doc comments must come before what they document, maybe a comment was \
+                          intended with `//`?");
+                err
+            }
+            Error::InclusiveRangeWithNoEnd => {
+                let mut err = struct_span_err!(
+                    handler,
+                    sp,
+                    E0586,
+                    "inclusive range with no end",
+                );
+                err.help("inclusive ranges must be bounded at the end (`..=b` or `a..=b`)");
+                err
+            }
+        }
+    }
+}
+
+pub(super) trait RecoverQPath: Sized + 'static {
+    const PATH_STYLE: PathStyle = PathStyle::Expr;
+    fn to_ty(&self) -> Option<P<Ty>>;
+    fn recovered(qself: Option<QSelf>, path: ast::Path) -> Self;
+}
+
+impl RecoverQPath for Ty {
+    const PATH_STYLE: PathStyle = PathStyle::Type;
+    fn to_ty(&self) -> Option<P<Ty>> {
+        Some(P(self.clone()))
+    }
+    fn recovered(qself: Option<QSelf>, path: ast::Path) -> Self {
+        Self {
+            span: path.span,
+            kind: TyKind::Path(qself, path),
+            id: ast::DUMMY_NODE_ID,
+        }
+    }
+}
+
+impl RecoverQPath for Pat {
+    fn to_ty(&self) -> Option<P<Ty>> {
+        self.to_ty()
+    }
+    fn recovered(qself: Option<QSelf>, path: ast::Path) -> Self {
+        Self {
+            span: path.span,
+            kind: PatKind::Path(qself, path),
+            id: ast::DUMMY_NODE_ID,
+        }
+    }
+}
+
+impl RecoverQPath for Expr {
+    fn to_ty(&self) -> Option<P<Ty>> {
+        self.to_ty()
+    }
+    fn recovered(qself: Option<QSelf>, path: ast::Path) -> Self {
+        Self {
+            span: path.span,
+            kind: ExprKind::Path(qself, path),
+            attrs: ThinVec::new(),
+            id: ast::DUMMY_NODE_ID,
+        }
+    }
+}
+
+/// Control whether the closing delimiter should be consumed when calling `Parser::consume_block`.
+crate enum ConsumeClosingDelim {
+    Yes,
+    No,
+}
+
+impl<'a> Parser<'a> {
+    pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> {
+        self.span_fatal(self.token.span, m)
+    }
+
+    crate fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
+        self.sess.span_diagnostic.struct_span_fatal(sp, m)
+    }
+
+    pub(super) fn span_fatal_err<S: Into<MultiSpan>>(
+        &self,
+        sp: S,
+        err: Error,
+    ) -> DiagnosticBuilder<'a> {
+        err.span_err(sp, self.diagnostic())
+    }
+
+    pub(super) fn bug(&self, m: &str) -> ! {
+        self.sess.span_diagnostic.span_bug(self.token.span, m)
+    }
+
+    pub(super) fn span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) {
+        self.sess.span_diagnostic.span_err(sp, m)
+    }
+
+    pub fn struct_span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
+        self.sess.span_diagnostic.struct_span_err(sp, m)
+    }
+
+    pub fn span_bug<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> ! {
+        self.sess.span_diagnostic.span_bug(sp, m)
+    }
+
+    pub(super) fn diagnostic(&self) -> &'a errors::Handler {
+        &self.sess.span_diagnostic
+    }
+
+    pub(super) fn span_to_snippet(&self, span: Span) -> Result<String, SpanSnippetError> {
+        self.sess.source_map().span_to_snippet(span)
+    }
+
+    pub(super) fn expected_ident_found(&self) -> DiagnosticBuilder<'a> {
+        let mut err = self.struct_span_err(
+            self.token.span,
+            &format!("expected identifier, found {}", self.this_token_descr()),
+        );
+        if let token::Ident(name, false) = self.token.kind {
+            if Ident::new(name, self.token.span).is_raw_guess() {
+                err.span_suggestion(
+                    self.token.span,
+                    "you can escape reserved keywords to use them as identifiers",
+                    format!("r#{}", name),
+                    Applicability::MaybeIncorrect,
+                );
+            }
+        }
+        if let Some(token_descr) = self.token_descr() {
+            err.span_label(self.token.span, format!("expected identifier, found {}", token_descr));
+        } else {
+            err.span_label(self.token.span, "expected identifier");
+            if self.token == token::Comma && self.look_ahead(1, |t| t.is_ident()) {
+                err.span_suggestion(
+                    self.token.span,
+                    "remove this comma",
+                    String::new(),
+                    Applicability::MachineApplicable,
+                );
+            }
+        }
+        err
+    }
+
+    pub(super) fn expected_one_of_not_found(
+        &mut self,
+        edible: &[TokenKind],
+        inedible: &[TokenKind],
+    ) -> PResult<'a, bool /* recovered */> {
+        fn tokens_to_string(tokens: &[TokenType]) -> String {
+            let mut i = tokens.iter();
+            // This might be a sign we need a connect method on `Iterator`.
+            let b = i.next()
+                     .map_or(String::new(), |t| t.to_string());
+            i.enumerate().fold(b, |mut b, (i, a)| {
+                if tokens.len() > 2 && i == tokens.len() - 2 {
+                    b.push_str(", or ");
+                } else if tokens.len() == 2 && i == tokens.len() - 2 {
+                    b.push_str(" or ");
+                } else {
+                    b.push_str(", ");
+                }
+                b.push_str(&a.to_string());
+                b
+            })
+        }
+
+        let mut expected = edible.iter()
+            .map(|x| TokenType::Token(x.clone()))
+            .chain(inedible.iter().map(|x| TokenType::Token(x.clone())))
+            .chain(self.expected_tokens.iter().cloned())
+            .collect::<Vec<_>>();
+        expected.sort_by_cached_key(|x| x.to_string());
+        expected.dedup();
+        let expect = tokens_to_string(&expected[..]);
+        let actual = self.this_token_descr();
+        let (msg_exp, (label_sp, label_exp)) = if expected.len() > 1 {
+            let short_expect = if expected.len() > 6 {
+                format!("{} possible tokens", expected.len())
+            } else {
+                expect.clone()
+            };
+            (format!("expected one of {}, found {}", expect, actual),
+                (self.sess.source_map().next_point(self.prev_span),
+                format!("expected one of {}", short_expect)))
+        } else if expected.is_empty() {
+            (format!("unexpected token: {}", actual),
+                (self.prev_span, "unexpected token after this".to_string()))
+        } else {
+            (format!("expected {}, found {}", expect, actual),
+                (self.sess.source_map().next_point(self.prev_span),
+                format!("expected {}", expect)))
+        };
+        self.last_unexpected_token_span = Some(self.token.span);
+        let mut err = self.fatal(&msg_exp);
+        if self.token.is_ident_named(sym::and) {
+            err.span_suggestion_short(
+                self.token.span,
+                "use `&&` instead of `and` for the boolean operator",
+                "&&".to_string(),
+                Applicability::MaybeIncorrect,
+            );
+        }
+        if self.token.is_ident_named(sym::or) {
+            err.span_suggestion_short(
+                self.token.span,
+                "use `||` instead of `or` for the boolean operator",
+                "||".to_string(),
+                Applicability::MaybeIncorrect,
+            );
+        }
+        let sp = if self.token == token::Eof {
+            // This is EOF; don't want to point at the following char, but rather the last token.
+            self.prev_span
+        } else {
+            label_sp
+        };
+        match self.recover_closing_delimiter(&expected.iter().filter_map(|tt| match tt {
+            TokenType::Token(t) => Some(t.clone()),
+            _ => None,
+        }).collect::<Vec<_>>(), err) {
+            Err(e) => err = e,
+            Ok(recovered) => {
+                return Ok(recovered);
+            }
+        }
+
+        let sm = self.sess.source_map();
+        if self.prev_span == DUMMY_SP {
+            // Account for macro context where the previous span might not be
+            // available to avoid incorrect output (#54841).
+            err.span_label(self.token.span, label_exp);
+        } else if !sm.is_multiline(self.token.span.shrink_to_hi().until(sp.shrink_to_lo())) {
+            // When the spans are in the same line, it means that the only content between
+            // them is whitespace, point at the found token in that case:
+            //
+            // X |     () => { syntax error };
+            //   |                    ^^^^^ expected one of 8 possible tokens here
+            //
+            // instead of having:
+            //
+            // X |     () => { syntax error };
+            //   |                   -^^^^^ unexpected token
+            //   |                   |
+            //   |                   expected one of 8 possible tokens here
+            err.span_label(self.token.span, label_exp);
+        } else {
+            err.span_label(sp, label_exp);
+            err.span_label(self.token.span, "unexpected token");
+        }
+        self.maybe_annotate_with_ascription(&mut err, false);
+        Err(err)
+    }
+
+    pub fn maybe_annotate_with_ascription(
+        &mut self,
+        err: &mut DiagnosticBuilder<'_>,
+        maybe_expected_semicolon: bool,
+    ) {
+        if let Some((sp, likely_path)) = self.last_type_ascription.take() {
+            let sm = self.sess.source_map();
+            let next_pos = sm.lookup_char_pos(self.token.span.lo());
+            let op_pos = sm.lookup_char_pos(sp.hi());
+
+            let allow_unstable = self.sess.unstable_features.is_nightly_build();
+
+            if likely_path {
+                err.span_suggestion(
+                    sp,
+                    "maybe write a path separator here",
+                    "::".to_string(),
+                    if allow_unstable {
+                        Applicability::MaybeIncorrect
+                    } else {
+                        Applicability::MachineApplicable
+                    },
+                );
+            } else if op_pos.line != next_pos.line && maybe_expected_semicolon {
+                err.span_suggestion(
+                    sp,
+                    "try using a semicolon",
+                    ";".to_string(),
+                    Applicability::MaybeIncorrect,
+                );
+            } else if allow_unstable {
+                err.span_label(sp, "tried to parse a type due to this type ascription");
+            } else {
+                err.span_label(sp, "tried to parse a type due to this");
+            }
+            if allow_unstable {
+                // Give extra information about type ascription only if it's a nightly compiler.
+                err.note("`#![feature(type_ascription)]` lets you annotate an expression with a \
+                          type: `<expr>: <type>`");
+                err.note("for more information, see \
+                          https://github.com/rust-lang/rust/issues/23416");
+            }
+        }
+    }
+
+    /// Eats and discards tokens until one of `kets` is encountered. Respects token trees,
+    /// passes through any errors encountered. Used for error recovery.
+    pub(super) fn eat_to_tokens(&mut self, kets: &[&TokenKind]) {
+        if let Err(ref mut err) = self.parse_seq_to_before_tokens(
+            kets,
+            SeqSep::none(),
+            TokenExpectType::Expect,
+            |p| Ok(p.parse_token_tree()),
+        ) {
+            err.cancel();
+        }
+    }
+
+    /// This function checks if there are trailing angle brackets and produces
+    /// a diagnostic to suggest removing them.
+    ///
+    /// ```ignore (diagnostic)
+    /// let _ = vec![1, 2, 3].into_iter().collect::<Vec<usize>>>>();
+    ///                                                        ^^ help: remove extra angle brackets
+    /// ```
+    pub(super) fn check_trailing_angle_brackets(&mut self, segment: &PathSegment, end: TokenKind) {
+        // This function is intended to be invoked after parsing a path segment where there are two
+        // cases:
+        //
+        // 1. A specific token is expected after the path segment.
+        //    eg. `x.foo(`, `x.foo::<u32>(` (parenthesis - method call),
+        //        `Foo::`, or `Foo::<Bar>::` (mod sep - continued path).
+        // 2. No specific token is expected after the path segment.
+        //    eg. `x.foo` (field access)
+        //
+        // This function is called after parsing `.foo` and before parsing the token `end` (if
+        // present). This includes any angle bracket arguments, such as `.foo::<u32>` or
+        // `Foo::<Bar>`.
+
+        // We only care about trailing angle brackets if we previously parsed angle bracket
+        // arguments. This helps stop us incorrectly suggesting that extra angle brackets be
+        // removed in this case:
+        //
+        // `x.foo >> (3)` (where `x.foo` is a `u32` for example)
+        //
+        // This case is particularly tricky as we won't notice it just looking at the tokens -
+        // it will appear the same (in terms of upcoming tokens) as below (since the `::<u32>` will
+        // have already been parsed):
+        //
+        // `x.foo::<u32>>>(3)`
+        let parsed_angle_bracket_args = segment.args
+            .as_ref()
+            .map(|args| args.is_angle_bracketed())
+            .unwrap_or(false);
+
+        debug!(
+            "check_trailing_angle_brackets: parsed_angle_bracket_args={:?}",
+            parsed_angle_bracket_args,
+        );
+        if !parsed_angle_bracket_args {
+            return;
+        }
+
+        // Keep the span at the start so we can highlight the sequence of `>` characters to be
+        // removed.
+        let lo = self.token.span;
+
+        // We need to look-ahead to see if we have `>` characters without moving the cursor forward
+        // (since we might have the field access case and the characters we're eating are
+        // actual operators and not trailing characters - ie `x.foo >> 3`).
+        let mut position = 0;
+
+        // We can encounter `>` or `>>` tokens in any order, so we need to keep track of how
+        // many of each (so we can correctly pluralize our error messages) and continue to
+        // advance.
+        let mut number_of_shr = 0;
+        let mut number_of_gt = 0;
+        while self.look_ahead(position, |t| {
+            trace!("check_trailing_angle_brackets: t={:?}", t);
+            if *t == token::BinOp(token::BinOpToken::Shr) {
+                number_of_shr += 1;
+                true
+            } else if *t == token::Gt {
+                number_of_gt += 1;
+                true
+            } else {
+                false
+            }
+        }) {
+            position += 1;
+        }
+
+        // If we didn't find any trailing `>` characters, then we have nothing to error about.
+        debug!(
+            "check_trailing_angle_brackets: number_of_gt={:?} number_of_shr={:?}",
+            number_of_gt, number_of_shr,
+        );
+        if number_of_gt < 1 && number_of_shr < 1 {
+            return;
+        }
+
+        // Finally, double check that we have our end token as otherwise this is the
+        // second case.
+        if self.look_ahead(position, |t| {
+            trace!("check_trailing_angle_brackets: t={:?}", t);
+            *t == end
+        }) {
+            // Eat from where we started until the end token so that parsing can continue
+            // as if we didn't have those extra angle brackets.
+            self.eat_to_tokens(&[&end]);
+            let span = lo.until(self.token.span);
+
+            let total_num_of_gt = number_of_gt + number_of_shr * 2;
+            self.diagnostic()
+                .struct_span_err(
+                    span,
+                    &format!("unmatched angle bracket{}", pluralize!(total_num_of_gt)),
+                )
+                .span_suggestion(
+                    span,
+                    &format!("remove extra angle bracket{}", pluralize!(total_num_of_gt)),
+                    String::new(),
+                    Applicability::MachineApplicable,
+                )
+                .emit();
+        }
+    }
+
+    /// Produces an error if comparison operators are chained (RFC #558).
+    /// We only need to check the LHS, not the RHS, because all comparison ops have same
+    /// precedence (see `fn precedence`) and are left-associative (see `fn fixity`).
+    ///
+    /// This can also be hit if someone incorrectly writes `foo<bar>()` when they should have used
+    /// the turbofish (`foo::<bar>()`) syntax. We attempt some heuristic recovery if that is the
+    /// case.
+    ///
+    /// Keep in mind that given that `outer_op.is_comparison()` holds and comparison ops are left
+    /// associative we can infer that we have:
+    ///
+    ///           outer_op
+    ///           /   \
+    ///     inner_op   r2
+    ///        /  \
+    ///     l1    r1
+    pub(super) fn check_no_chained_comparison(
+        &mut self,
+        lhs: &Expr,
+        outer_op: &AssocOp,
+    ) -> PResult<'a, Option<P<Expr>>> {
+        debug_assert!(
+            outer_op.is_comparison(),
+            "check_no_chained_comparison: {:?} is not comparison",
+            outer_op,
+        );
+
+        let mk_err_expr = |this: &Self, span| {
+            Ok(Some(this.mk_expr(span, ExprKind::Err, ThinVec::new())))
+        };
+
+        match lhs.kind {
+            ExprKind::Binary(op, _, _) if op.node.is_comparison() => {
+                // Respan to include both operators.
+                let op_span = op.span.to(self.prev_span);
+                let mut err = self.struct_span_err(
+                    op_span,
+                    "chained comparison operators require parentheses",
+                );
+
+                let suggest = |err: &mut DiagnosticBuilder<'_>| {
+                    err.span_suggestion_verbose(
+                        op_span.shrink_to_lo(),
+                        TURBOFISH,
+                        "::".to_string(),
+                        Applicability::MaybeIncorrect,
+                    );
+                };
+
+                if op.node == BinOpKind::Lt &&
+                    *outer_op == AssocOp::Less ||  // Include `<` to provide this recommendation
+                    *outer_op == AssocOp::Greater  // even in a case like the following:
+                {                                  //     Foo<Bar<Baz<Qux, ()>>>
+                    if *outer_op == AssocOp::Less {
+                        let snapshot = self.clone();
+                        self.bump();
+                        // So far we have parsed `foo<bar<`, consume the rest of the type args.
+                        let modifiers = [
+                            (token::Lt, 1),
+                            (token::Gt, -1),
+                            (token::BinOp(token::Shr), -2),
+                        ];
+                        self.consume_tts(1, &modifiers[..]);
+
+                        if !&[
+                            token::OpenDelim(token::Paren),
+                            token::ModSep,
+                        ].contains(&self.token.kind) {
+                            // We don't have `foo< bar >(` or `foo< bar >::`, so we rewind the
+                            // parser and bail out.
+                            mem::replace(self, snapshot.clone());
+                        }
+                    }
+                    return if token::ModSep == self.token.kind {
+                        // We have some certainty that this was a bad turbofish at this point.
+                        // `foo< bar >::`
+                        suggest(&mut err);
+
+                        let snapshot = self.clone();
+                        self.bump(); // `::`
+
+                        // Consume the rest of the likely `foo<bar>::new()` or return at `foo<bar>`.
+                        match self.parse_expr() {
+                            Ok(_) => {
+                                // 99% certain that the suggestion is correct, continue parsing.
+                                err.emit();
+                                // FIXME: actually check that the two expressions in the binop are
+                                // paths and resynthesize new fn call expression instead of using
+                                // `ExprKind::Err` placeholder.
+                                mk_err_expr(self, lhs.span.to(self.prev_span))
+                            }
+                            Err(mut expr_err) => {
+                                expr_err.cancel();
+                                // Not entirely sure now, but we bubble the error up with the
+                                // suggestion.
+                                mem::replace(self, snapshot);
+                                Err(err)
+                            }
+                        }
+                    } else if token::OpenDelim(token::Paren) == self.token.kind {
+                        // We have high certainty that this was a bad turbofish at this point.
+                        // `foo< bar >(`
+                        suggest(&mut err);
+                        // Consume the fn call arguments.
+                        match self.consume_fn_args() {
+                            Err(()) => Err(err),
+                            Ok(()) => {
+                                err.emit();
+                                // FIXME: actually check that the two expressions in the binop are
+                                // paths and resynthesize new fn call expression instead of using
+                                // `ExprKind::Err` placeholder.
+                                mk_err_expr(self, lhs.span.to(self.prev_span))
+                            }
+                        }
+                    } else {
+                        // All we know is that this is `foo < bar >` and *nothing* else. Try to
+                        // be helpful, but don't attempt to recover.
+                        err.help(TURBOFISH);
+                        err.help("or use `(...)` if you meant to specify fn arguments");
+                        // These cases cause too many knock-down errors, bail out (#61329).
+                        Err(err)
+                    };
+                }
+                err.emit();
+            }
+            _ => {}
+        }
+        Ok(None)
+    }
+
+    fn consume_fn_args(&mut self) -> Result<(), ()> {
+        let snapshot = self.clone();
+        self.bump(); // `(`
+
+        // Consume the fn call arguments.
+        let modifiers = [
+            (token::OpenDelim(token::Paren), 1),
+            (token::CloseDelim(token::Paren), -1),
+        ];
+        self.consume_tts(1, &modifiers[..]);
+
+        if self.token.kind == token::Eof {
+            // Not entirely sure that what we consumed were fn arguments, rollback.
+            mem::replace(self, snapshot);
+            Err(())
+        } else {
+            // 99% certain that the suggestion is correct, continue parsing.
+            Ok(())
+        }
+    }
+
+    pub(super) fn maybe_report_ambiguous_plus(
+        &mut self,
+        allow_plus: bool,
+        impl_dyn_multi: bool,
+        ty: &Ty,
+    ) {
+        if !allow_plus && impl_dyn_multi {
+            let sum_with_parens = format!("({})", pprust::ty_to_string(&ty));
+            self.struct_span_err(ty.span, "ambiguous `+` in a type")
+                .span_suggestion(
+                    ty.span,
+                    "use parentheses to disambiguate",
+                    sum_with_parens,
+                    Applicability::MachineApplicable,
+                )
+                .emit();
+        }
+    }
+
+    pub(super) fn maybe_recover_from_bad_type_plus(
+        &mut self,
+        allow_plus: bool,
+        ty: &Ty,
+    ) -> PResult<'a, ()> {
+        // Do not add `+` to expected tokens.
+        if !allow_plus || !self.token.is_like_plus() {
+            return Ok(());
+        }
+
+        self.bump(); // `+`
+        let bounds = self.parse_generic_bounds(None)?;
+        let sum_span = ty.span.to(self.prev_span);
+
+        let mut err = struct_span_err!(
+            self.sess.span_diagnostic,
+            sum_span,
+            E0178,
+            "expected a path on the left-hand side of `+`, not `{}`",
+            pprust::ty_to_string(ty)
+        );
+
+        match ty.kind {
+            TyKind::Rptr(ref lifetime, ref mut_ty) => {
+                let sum_with_parens = pprust::to_string(|s| {
+                    s.s.word("&");
+                    s.print_opt_lifetime(lifetime);
+                    s.print_mutability(mut_ty.mutbl);
+                    s.popen();
+                    s.print_type(&mut_ty.ty);
+                    s.print_type_bounds(" +", &bounds);
+                    s.pclose()
+                });
+                err.span_suggestion(
+                    sum_span,
+                    "try adding parentheses",
+                    sum_with_parens,
+                    Applicability::MachineApplicable,
+                );
+            }
+            TyKind::Ptr(..) | TyKind::BareFn(..) => {
+                err.span_label(sum_span, "perhaps you forgot parentheses?");
+            }
+            _ => {
+                err.span_label(sum_span, "expected a path");
+            }
+        }
+        err.emit();
+        Ok(())
+    }
+
+    /// Tries to recover from associated item paths like `[T]::AssocItem` / `(T, U)::AssocItem`.
+    /// Attempts to convert the base expression/pattern/type into a type, parses the `::AssocItem`
+    /// tail, and combines them into a `<Ty>::AssocItem` expression/pattern/type.
+    pub(super) fn maybe_recover_from_bad_qpath<T: RecoverQPath>(
+        &mut self,
+        base: P<T>,
+        allow_recovery: bool,
+    ) -> PResult<'a, P<T>> {
+        // Do not add `::` to expected tokens.
+        if allow_recovery && self.token == token::ModSep {
+            if let Some(ty) = base.to_ty() {
+                return self.maybe_recover_from_bad_qpath_stage_2(ty.span, ty);
+            }
+        }
+        Ok(base)
+    }
+
+    /// Given an already parsed `Ty`, parses the `::AssocItem` tail and
+    /// combines them into a `<Ty>::AssocItem` expression/pattern/type.
+    pub(super) fn maybe_recover_from_bad_qpath_stage_2<T: RecoverQPath>(
+        &mut self,
+        ty_span: Span,
+        ty: P<Ty>,
+    ) -> PResult<'a, P<T>> {
+        self.expect(&token::ModSep)?;
+
+        let mut path = ast::Path {
+            segments: Vec::new(),
+            span: DUMMY_SP,
+        };
+        self.parse_path_segments(&mut path.segments, T::PATH_STYLE)?;
+        path.span = ty_span.to(self.prev_span);
+
+        let ty_str = self
+            .span_to_snippet(ty_span)
+            .unwrap_or_else(|_| pprust::ty_to_string(&ty));
+        self.diagnostic()
+            .struct_span_err(path.span, "missing angle brackets in associated item path")
+            .span_suggestion(
+                // This is a best-effort recovery.
+                path.span,
+                "try",
+                format!("<{}>::{}", ty_str, pprust::path_to_string(&path)),
+                Applicability::MaybeIncorrect,
+            )
+            .emit();
+
+        let path_span = ty_span.shrink_to_hi(); // Use an empty path since `position == 0`.
+        Ok(P(T::recovered(
+            Some(QSelf {
+                ty,
+                path_span,
+                position: 0,
+            }),
+            path,
+        )))
+    }
+
+    pub(super) fn maybe_consume_incorrect_semicolon(&mut self, items: &[P<Item>]) -> bool {
+        if self.eat(&token::Semi) {
+            let mut err = self.struct_span_err(self.prev_span, "expected item, found `;`");
+            err.span_suggestion_short(
+                self.prev_span,
+                "remove this semicolon",
+                String::new(),
+                Applicability::MachineApplicable,
+            );
+            if !items.is_empty() {
+                let previous_item = &items[items.len() - 1];
+                let previous_item_kind_name = match previous_item.kind {
+                    // Say "braced struct" because tuple-structs and
+                    // braceless-empty-struct declarations do take a semicolon.
+                    ItemKind::Struct(..) => Some("braced struct"),
+                    ItemKind::Enum(..) => Some("enum"),
+                    ItemKind::Trait(..) => Some("trait"),
+                    ItemKind::Union(..) => Some("union"),
+                    _ => None,
+                };
+                if let Some(name) = previous_item_kind_name {
+                    err.help(&format!(
+                        "{} declarations are not followed by a semicolon",
+                        name
+                    ));
+                }
+            }
+            err.emit();
+            true
+        } else {
+            false
+        }
+    }
+
+    /// Creates a `DiagnosticBuilder` for an unexpected token `t` and tries to recover if it is a
+    /// closing delimiter.
+    pub(super) fn unexpected_try_recover(
+        &mut self,
+        t: &TokenKind,
+    ) -> PResult<'a, bool /* recovered */> {
+        let token_str = pprust::token_kind_to_string(t);
+        let this_token_str = self.this_token_descr();
+        let (prev_sp, sp) = match (&self.token.kind, self.subparser_name) {
+            // Point at the end of the macro call when reaching end of macro arguments.
+            (token::Eof, Some(_)) => {
+                let sp = self.sess.source_map().next_point(self.token.span);
+                (sp, sp)
+            }
+            // We don't want to point at the following span after DUMMY_SP.
+            // This happens when the parser finds an empty TokenStream.
+            _ if self.prev_span == DUMMY_SP => (self.token.span, self.token.span),
+            // EOF, don't want to point at the following char, but rather the last token.
+            (token::Eof, None) => (self.prev_span, self.token.span),
+            _ => (self.sess.source_map().next_point(self.prev_span), self.token.span),
+        };
+        let msg = format!(
+            "expected `{}`, found {}",
+            token_str,
+            match (&self.token.kind, self.subparser_name) {
+                (token::Eof, Some(origin)) => format!("end of {}", origin),
+                _ => this_token_str,
+            },
+        );
+        let mut err = self.struct_span_err(sp, &msg);
+        let label_exp = format!("expected `{}`", token_str);
+        match self.recover_closing_delimiter(&[t.clone()], err) {
+            Err(e) => err = e,
+            Ok(recovered) => {
+                return Ok(recovered);
+            }
+        }
+        let sm = self.sess.source_map();
+        if !sm.is_multiline(prev_sp.until(sp)) {
+            // When the spans are in the same line, it means that the only content
+            // between them is whitespace, point only at the found token.
+            err.span_label(sp, label_exp);
+        } else {
+            err.span_label(prev_sp, label_exp);
+            err.span_label(sp, "unexpected token");
+        }
+        Err(err)
+    }
+
+    pub(super) fn expect_semi(&mut self) -> PResult<'a, ()> {
+        if self.eat(&token::Semi) {
+            return Ok(());
+        }
+        let sm = self.sess.source_map();
+        let msg = format!("expected `;`, found `{}`", self.this_token_descr());
+        let appl = Applicability::MachineApplicable;
+        if self.token.span == DUMMY_SP || self.prev_span == DUMMY_SP {
+            // Likely inside a macro, can't provide meaninful suggestions.
+            return self.expect(&token::Semi).map(|_| ());
+        } else if !sm.is_multiline(self.prev_span.until(self.token.span)) {
+            // The current token is in the same line as the prior token, not recoverable.
+        } else if self.look_ahead(1, |t| t == &token::CloseDelim(token::Brace)
+            || token_can_begin_expr(t) && t.kind != token::Colon
+        ) && [token::Comma, token::Colon].contains(&self.token.kind) {
+            // Likely typo: `,` → `;` or `:` → `;`. This is triggered if the current token is
+            // either `,` or `:`, and the next token could either start a new statement or is a
+            // block close. For example:
+            //
+            //   let x = 32:
+            //   let y = 42;
+            self.bump();
+            let sp = self.prev_span;
+            self.struct_span_err(sp, &msg)
+                .span_suggestion(sp, "change this to `;`", ";".to_string(), appl)
+                .emit();
+            return Ok(())
+        } else if self.look_ahead(0, |t| t == &token::CloseDelim(token::Brace) || (
+                token_can_begin_expr(t)
+                && t != &token::Semi
+                && t != &token::Pound // Avoid triggering with too many trailing `#` in raw string.
+        )) {
+            // Missing semicolon typo. This is triggered if the next token could either start a
+            // new statement or is a block close. For example:
+            //
+            //   let x = 32
+            //   let y = 42;
+            let sp = self.prev_span.shrink_to_hi();
+            self.struct_span_err(sp, &msg)
+                .span_label(self.token.span, "unexpected token")
+                .span_suggestion_short(sp, "add `;` here", ";".to_string(), appl)
+                .emit();
+            return Ok(())
+        }
+        self.expect(&token::Semi).map(|_| ()) // Error unconditionally
+    }
+
+    pub(super) fn parse_semi_or_incorrect_foreign_fn_body(
+        &mut self,
+        ident: &Ident,
+        extern_sp: Span,
+    ) -> PResult<'a, ()> {
+        if self.token != token::Semi {
+            // This might be an incorrect fn definition (#62109).
+            let parser_snapshot = self.clone();
+            match self.parse_inner_attrs_and_block() {
+                Ok((_, body)) => {
+                    self.struct_span_err(ident.span, "incorrect `fn` inside `extern` block")
+                        .span_label(ident.span, "can't have a body")
+                        .span_label(body.span, "this body is invalid here")
+                        .span_label(
+                            extern_sp,
+                            "`extern` blocks define existing foreign functions and `fn`s \
+                             inside of them cannot have a body")
+                        .help("you might have meant to write a function accessible through ffi, \
+                               which can be done by writing `extern fn` outside of the \
+                               `extern` block")
+                        .note("for more information, visit \
+                               https://doc.rust-lang.org/std/keyword.extern.html")
+                        .emit();
+                }
+                Err(mut err) => {
+                    err.cancel();
+                    mem::replace(self, parser_snapshot);
+                    self.expect_semi()?;
+                }
+            }
+        } else {
+            self.bump();
+        }
+        Ok(())
+    }
+
+    /// Consumes alternative await syntaxes like `await!(<expr>)`, `await <expr>`,
+    /// `await? <expr>`, `await(<expr>)`, and `await { <expr> }`.
+    pub(super) fn parse_incorrect_await_syntax(
+        &mut self,
+        lo: Span,
+        await_sp: Span,
+    ) -> PResult<'a, (Span, ExprKind)> {
+        if self.token == token::Not {
+            // Handle `await!(<expr>)`.
+            self.expect(&token::Not)?;
+            self.expect(&token::OpenDelim(token::Paren))?;
+            let expr = self.parse_expr()?;
+            self.expect(&token::CloseDelim(token::Paren))?;
+            let sp = self.error_on_incorrect_await(lo, self.prev_span, &expr, false);
+            return Ok((sp, ExprKind::Await(expr)))
+        }
+
+        let is_question = self.eat(&token::Question); // Handle `await? <expr>`.
+        let expr = if self.token == token::OpenDelim(token::Brace) {
+            // Handle `await { <expr> }`.
+            // This needs to be handled separatedly from the next arm to avoid
+            // interpreting `await { <expr> }?` as `<expr>?.await`.
+            self.parse_block_expr(
+                None,
+                self.token.span,
+                BlockCheckMode::Default,
+                ThinVec::new(),
+            )
+        } else {
+            self.parse_expr()
+        }.map_err(|mut err| {
+            err.span_label(await_sp, "while parsing this incorrect await expression");
+            err
+        })?;
+        let sp = self.error_on_incorrect_await(lo, expr.span, &expr, is_question);
+        Ok((sp, ExprKind::Await(expr)))
+    }
+
+    fn error_on_incorrect_await(&self, lo: Span, hi: Span, expr: &Expr, is_question: bool) -> Span {
+        let expr_str = self.span_to_snippet(expr.span)
+            .unwrap_or_else(|_| pprust::expr_to_string(&expr));
+        let suggestion = format!("{}.await{}", expr_str, if is_question { "?" } else { "" });
+        let sp = lo.to(hi);
+        let app = match expr.kind {
+            ExprKind::Try(_) => Applicability::MaybeIncorrect, // `await <expr>?`
+            _ => Applicability::MachineApplicable,
+        };
+        self.struct_span_err(sp, "incorrect use of `await`")
+            .span_suggestion(sp, "`await` is a postfix operation", suggestion, app)
+            .emit();
+        sp
+    }
+
+    /// If encountering `future.await()`, consumes and emits an error.
+    pub(super) fn recover_from_await_method_call(&mut self) {
+        if self.token == token::OpenDelim(token::Paren) &&
+            self.look_ahead(1, |t| t == &token::CloseDelim(token::Paren))
+        {
+            // future.await()
+            let lo = self.token.span;
+            self.bump(); // (
+            let sp = lo.to(self.token.span);
+            self.bump(); // )
+            self.struct_span_err(sp, "incorrect use of `await`")
+                .span_suggestion(
+                    sp,
+                    "`await` is not a method call, remove the parentheses",
+                    String::new(),
+                    Applicability::MachineApplicable,
+                ).emit()
+        }
+    }
+
+    /// Recovers a situation like `for ( $pat in $expr )`
+    /// and suggest writing `for $pat in $expr` instead.
+    ///
+    /// This should be called before parsing the `$block`.
+    pub(super) fn recover_parens_around_for_head(
+        &mut self,
+        pat: P<Pat>,
+        expr: &Expr,
+        begin_paren: Option<Span>,
+    ) -> P<Pat> {
+        match (&self.token.kind, begin_paren) {
+            (token::CloseDelim(token::Paren), Some(begin_par_sp)) => {
+                self.bump();
+
+                let pat_str = self
+                    // Remove the `(` from the span of the pattern:
+                    .span_to_snippet(pat.span.trim_start(begin_par_sp).unwrap())
+                    .unwrap_or_else(|_| pprust::pat_to_string(&pat));
+
+                self.struct_span_err(self.prev_span, "unexpected closing `)`")
+                    .span_label(begin_par_sp, "opening `(`")
+                    .span_suggestion(
+                        begin_par_sp.to(self.prev_span),
+                        "remove parenthesis in `for` loop",
+                        format!("{} in {}", pat_str, pprust::expr_to_string(&expr)),
+                        // With e.g. `for (x) in y)` this would replace `(x) in y)`
+                        // with `x) in y)` which is syntactically invalid.
+                        // However, this is prevented before we get here.
+                        Applicability::MachineApplicable,
+                    )
+                    .emit();
+
+                // Unwrap `(pat)` into `pat` to avoid the `unused_parens` lint.
+                pat.and_then(|pat| match pat.kind {
+                    PatKind::Paren(pat) => pat,
+                    _ => P(pat),
+                })
+            }
+            _ => pat,
+        }
+    }
+
+    pub(super) fn could_ascription_be_path(&self, node: &ast::ExprKind) -> bool {
+        (self.token == token::Lt && // `foo:<bar`, likely a typoed turbofish.
+            self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
+        ) ||
+            self.token.is_ident() &&
+            match node {
+                // `foo::` → `foo:` or `foo.bar::` → `foo.bar:`
+                ast::ExprKind::Path(..) | ast::ExprKind::Field(..) => true,
+                _ => false,
+            } &&
+            !self.token.is_reserved_ident() &&           // v `foo:bar(baz)`
+            self.look_ahead(1, |t| t == &token::OpenDelim(token::Paren)) ||
+            self.look_ahead(1, |t| t == &token::Lt) &&     // `foo:bar<baz`
+            self.look_ahead(2, |t| t.is_ident()) ||
+            self.look_ahead(1, |t| t == &token::Colon) &&  // `foo:bar:baz`
+            self.look_ahead(2, |t| t.is_ident()) ||
+            self.look_ahead(1, |t| t == &token::ModSep) &&
+            (self.look_ahead(2, |t| t.is_ident()) ||   // `foo:bar::baz`
+             self.look_ahead(2, |t| t == &token::Lt))  // `foo:bar::<baz>`
+    }
+
+    pub(super) fn recover_seq_parse_error(
+        &mut self,
+        delim: token::DelimToken,
+        lo: Span,
+        result: PResult<'a, P<Expr>>,
+    ) -> P<Expr> {
+        match result {
+            Ok(x) => x,
+            Err(mut err) => {
+                err.emit();
+                // Recover from parse error, callers expect the closing delim to be consumed.
+                self.consume_block(delim, ConsumeClosingDelim::Yes);
+                self.mk_expr(lo.to(self.prev_span), ExprKind::Err, ThinVec::new())
+            }
+        }
+    }
+
+    pub(super) fn recover_closing_delimiter(
+        &mut self,
+        tokens: &[TokenKind],
+        mut err: DiagnosticBuilder<'a>,
+    ) -> PResult<'a, bool> {
+        let mut pos = None;
+        // We want to use the last closing delim that would apply.
+        for (i, unmatched) in self.unclosed_delims.iter().enumerate().rev() {
+            if tokens.contains(&token::CloseDelim(unmatched.expected_delim))
+                && Some(self.token.span) > unmatched.unclosed_span
+            {
+                pos = Some(i);
+            }
+        }
+        match pos {
+            Some(pos) => {
+                // Recover and assume that the detected unclosed delimiter was meant for
+                // this location. Emit the diagnostic and act as if the delimiter was
+                // present for the parser's sake.
+
+                 // Don't attempt to recover from this unclosed delimiter more than once.
+                let unmatched = self.unclosed_delims.remove(pos);
+                let delim = TokenType::Token(token::CloseDelim(unmatched.expected_delim));
+                if unmatched.found_delim.is_none() {
+                    // We encountered `Eof`, set this fact here to avoid complaining about missing
+                    // `fn main()` when we found place to suggest the closing brace.
+                    *self.sess.reached_eof.borrow_mut() = true;
+                }
+
+                // We want to suggest the inclusion of the closing delimiter where it makes
+                // the most sense, which is immediately after the last token:
+                //
+                //  {foo(bar {}}
+                //      -      ^
+                //      |      |
+                //      |      help: `)` may belong here
+                //      |
+                //      unclosed delimiter
+                if let Some(sp) = unmatched.unclosed_span {
+                    err.span_label(sp, "unclosed delimiter");
+                }
+                err.span_suggestion_short(
+                    self.sess.source_map().next_point(self.prev_span),
+                    &format!("{} may belong here", delim.to_string()),
+                    delim.to_string(),
+                    Applicability::MaybeIncorrect,
+                );
+                if unmatched.found_delim.is_none() {
+                    // Encountered `Eof` when lexing blocks. Do not recover here to avoid knockdown
+                    // errors which would be emitted elsewhere in the parser and let other error
+                    // recovery consume the rest of the file.
+                    Err(err)
+                } else {
+                    err.emit();
+                    self.expected_tokens.clear();  // Reduce the number of errors.
+                    Ok(true)
+                }
+            }
+            _ => Err(err),
+        }
+    }
+
+    /// Recovers from `pub` keyword in places where it seems _reasonable_ but isn't valid.
+    pub(super) fn eat_bad_pub(&mut self) {
+        // When `unclosed_delims` is populated, it means that the code being parsed is already
+        // quite malformed, which might mean that, for example, a pub struct definition could be
+        // parsed as being a trait item, which is invalid and this error would trigger
+        // unconditionally, resulting in misleading diagnostics. Because of this, we only attempt
+        // this nice to have recovery for code that is otherwise well formed.
+        if self.token.is_keyword(kw::Pub) && self.unclosed_delims.is_empty() {
+            match self.parse_visibility(false) {
+                Ok(vis) => {
+                    self.diagnostic()
+                        .struct_span_err(vis.span, "unnecessary visibility qualifier")
+                        .span_label(vis.span, "`pub` not permitted here")
+                        .emit();
+                }
+                Err(mut err) => err.emit(),
+            }
+        }
+    }
+
+    /// Eats tokens until we can be relatively sure we reached the end of the
+    /// statement. This is something of a best-effort heuristic.
+    ///
+    /// We terminate when we find an unmatched `}` (without consuming it).
+    pub(super) fn recover_stmt(&mut self) {
+        self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore)
+    }
+
+    /// If `break_on_semi` is `Break`, then we will stop consuming tokens after
+    /// finding (and consuming) a `;` outside of `{}` or `[]` (note that this is
+    /// approximate -- it can mean we break too early due to macros, but that
+    /// should only lead to sub-optimal recovery, not inaccurate parsing).
+    ///
+    /// If `break_on_block` is `Break`, then we will stop consuming tokens
+    /// after finding (and consuming) a brace-delimited block.
+    pub(super) fn recover_stmt_(
+        &mut self,
+        break_on_semi: SemiColonMode,
+        break_on_block: BlockMode,
+    ) {
+        let mut brace_depth = 0;
+        let mut bracket_depth = 0;
+        let mut in_block = false;
+        debug!("recover_stmt_ enter loop (semi={:?}, block={:?})",
+               break_on_semi, break_on_block);
+        loop {
+            debug!("recover_stmt_ loop {:?}", self.token);
+            match self.token.kind {
+                token::OpenDelim(token::DelimToken::Brace) => {
+                    brace_depth += 1;
+                    self.bump();
+                    if break_on_block == BlockMode::Break &&
+                       brace_depth == 1 &&
+                       bracket_depth == 0 {
+                        in_block = true;
+                    }
+                }
+                token::OpenDelim(token::DelimToken::Bracket) => {
+                    bracket_depth += 1;
+                    self.bump();
+                }
+                token::CloseDelim(token::DelimToken::Brace) => {
+                    if brace_depth == 0 {
+                        debug!("recover_stmt_ return - close delim {:?}", self.token);
+                        break;
+                    }
+                    brace_depth -= 1;
+                    self.bump();
+                    if in_block && bracket_depth == 0 && brace_depth == 0 {
+                        debug!("recover_stmt_ return - block end {:?}", self.token);
+                        break;
+                    }
+                }
+                token::CloseDelim(token::DelimToken::Bracket) => {
+                    bracket_depth -= 1;
+                    if bracket_depth < 0 {
+                        bracket_depth = 0;
+                    }
+                    self.bump();
+                }
+                token::Eof => {
+                    debug!("recover_stmt_ return - Eof");
+                    break;
+                }
+                token::Semi => {
+                    self.bump();
+                    if break_on_semi == SemiColonMode::Break &&
+                       brace_depth == 0 &&
+                       bracket_depth == 0 {
+                        debug!("recover_stmt_ return - Semi");
+                        break;
+                    }
+                }
+                token::Comma if break_on_semi == SemiColonMode::Comma &&
+                       brace_depth == 0 &&
+                       bracket_depth == 0 =>
+                {
+                    debug!("recover_stmt_ return - Semi");
+                    break;
+                }
+                _ => {
+                    self.bump()
+                }
+            }
+        }
+    }
+
+    pub(super) fn check_for_for_in_in_typo(&mut self, in_span: Span) {
+        if self.eat_keyword(kw::In) {
+            // a common typo: `for _ in in bar {}`
+            self.struct_span_err(self.prev_span, "expected iterable, found keyword `in`")
+                .span_suggestion_short(
+                    in_span.until(self.prev_span),
+                    "remove the duplicated `in`",
+                    String::new(),
+                    Applicability::MachineApplicable,
+                )
+                .emit();
+        }
+    }
+
+    pub(super) fn expected_semi_or_open_brace<T>(&mut self) -> PResult<'a, T> {
+        let token_str = self.this_token_descr();
+        let mut err = self.fatal(&format!("expected `;` or `{{`, found {}", token_str));
+        err.span_label(self.token.span, "expected `;` or `{`");
+        Err(err)
+    }
+
+    pub(super) fn eat_incorrect_doc_comment_for_param_type(&mut self) {
+        if let token::DocComment(_) = self.token.kind {
+            self.struct_span_err(
+                self.token.span,
+                "documentation comments cannot be applied to a function parameter's type",
+            )
+            .span_label(self.token.span, "doc comments are not allowed here")
+            .emit();
+            self.bump();
+        } else if self.token == token::Pound && self.look_ahead(1, |t| {
+            *t == token::OpenDelim(token::Bracket)
+        }) {
+            let lo = self.token.span;
+            // Skip every token until next possible arg.
+            while self.token != token::CloseDelim(token::Bracket) {
+                self.bump();
+            }
+            let sp = lo.to(self.token.span);
+            self.bump();
+            self.struct_span_err(
+                sp,
+                "attributes cannot be applied to a function parameter's type",
+            )
+            .span_label(sp, "attributes are not allowed here")
+            .emit();
+        }
+    }
+
+    pub(super) fn parameter_without_type(
+        &mut self,
+        err: &mut DiagnosticBuilder<'_>,
+        pat: P<ast::Pat>,
+        require_name: bool,
+        is_self_allowed: bool,
+        is_trait_item: bool,
+    ) -> Option<Ident> {
+        // If we find a pattern followed by an identifier, it could be an (incorrect)
+        // C-style parameter declaration.
+        if self.check_ident() && self.look_ahead(1, |t| {
+            *t == token::Comma || *t == token::CloseDelim(token::Paren)
+        }) { // `fn foo(String s) {}`
+            let ident = self.parse_ident().unwrap();
+            let span = pat.span.with_hi(ident.span.hi());
+
+            err.span_suggestion(
+                span,
+                "declare the type after the parameter binding",
+                String::from("<identifier>: <type>"),
+                Applicability::HasPlaceholders,
+            );
+            return Some(ident);
+        } else if let PatKind::Ident(_, ident, _) = pat.kind {
+            if require_name && (
+                is_trait_item ||
+                self.token == token::Comma ||
+                self.token == token::Lt ||
+                self.token == token::CloseDelim(token::Paren)
+            ) { // `fn foo(a, b) {}`, `fn foo(a<x>, b<y>) {}` or `fn foo(usize, usize) {}`
+                if is_self_allowed {
+                    err.span_suggestion(
+                        pat.span,
+                        "if this is a `self` type, give it a parameter name",
+                        format!("self: {}", ident),
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                // Avoid suggesting that `fn foo(HashMap<u32>)` is fixed with a change to
+                // `fn foo(HashMap: TypeName<u32>)`.
+                if self.token != token::Lt {
+                    err.span_suggestion(
+                        pat.span,
+                        "if this was a parameter name, give it a type",
+                        format!("{}: TypeName", ident),
+                        Applicability::HasPlaceholders,
+                    );
+                }
+                err.span_suggestion(
+                    pat.span,
+                    "if this is a type, explicitly ignore the parameter name",
+                    format!("_: {}", ident),
+                    Applicability::MachineApplicable,
+                );
+                err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)");
+
+                // Don't attempt to recover by using the `X` in `X<Y>` as the parameter name.
+                return if self.token == token::Lt { None } else { Some(ident) };
+            }
+        }
+        None
+    }
+
+    pub(super) fn recover_arg_parse(&mut self) -> PResult<'a, (P<ast::Pat>, P<ast::Ty>)> {
+        let pat = self.parse_pat(Some("argument name"))?;
+        self.expect(&token::Colon)?;
+        let ty = self.parse_ty()?;
+
+        self.diagnostic()
+            .struct_span_err_with_code(
+                pat.span,
+                "patterns aren't allowed in methods without bodies",
+                DiagnosticId::Error("E0642".into()),
+            )
+            .span_suggestion_short(
+                pat.span,
+                "give this argument a name or use an underscore to ignore it",
+                "_".to_owned(),
+                Applicability::MachineApplicable,
+            )
+            .emit();
+
+        // Pretend the pattern is `_`, to avoid duplicate errors from AST validation.
+        let pat = P(Pat {
+            kind: PatKind::Wild,
+            span: pat.span,
+            id: ast::DUMMY_NODE_ID
+        });
+        Ok((pat, ty))
+    }
+
+    pub(super) fn recover_bad_self_param(
+        &mut self,
+        mut param: ast::Param,
+        is_trait_item: bool,
+    ) -> PResult<'a, ast::Param> {
+        let sp = param.pat.span;
+        param.ty.kind = TyKind::Err;
+        let mut err = self.struct_span_err(sp, "unexpected `self` parameter in function");
+        if is_trait_item {
+            err.span_label(sp, "must be the first associated function parameter");
+        } else {
+            err.span_label(sp, "not valid as function parameter");
+            err.note("`self` is only valid as the first parameter of an associated function");
+        }
+        err.emit();
+        Ok(param)
+    }
+
+    pub(super) fn consume_block(
+        &mut self,
+        delim: token::DelimToken,
+        consume_close: ConsumeClosingDelim,
+    ) {
+        let mut brace_depth = 0;
+        loop {
+            if self.eat(&token::OpenDelim(delim)) {
+                brace_depth += 1;
+            } else if self.check(&token::CloseDelim(delim)) {
+                if brace_depth == 0 {
+                    if let ConsumeClosingDelim::Yes = consume_close {
+                        // Some of the callers of this method expect to be able to parse the
+                        // closing delimiter themselves, so we leave it alone. Otherwise we advance
+                        // the parser.
+                        self.bump();
+                    }
+                    return;
+                } else {
+                    self.bump();
+                    brace_depth -= 1;
+                    continue;
+                }
+            } else if self.token == token::Eof || self.eat(&token::CloseDelim(token::NoDelim)) {
+                return;
+            } else {
+                self.bump();
+            }
+        }
+    }
+
+    pub(super) fn expected_expression_found(&self) -> DiagnosticBuilder<'a> {
+        let (span, msg) = match (&self.token.kind, self.subparser_name) {
+            (&token::Eof, Some(origin)) => {
+                let sp = self.sess.source_map().next_point(self.token.span);
+                (sp, format!("expected expression, found end of {}", origin))
+            }
+            _ => (self.token.span, format!(
+                "expected expression, found {}",
+                self.this_token_descr(),
+            )),
+        };
+        let mut err = self.struct_span_err(span, &msg);
+        let sp = self.sess.source_map().start_point(self.token.span);
+        if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow().get(&sp) {
+            self.sess.expr_parentheses_needed(&mut err, *sp, None);
+        }
+        err.span_label(span, "expected expression");
+        err
+    }
+
+    fn consume_tts(
+        &mut self,
+        mut acc: i64, // `i64` because malformed code can have more closing delims than opening.
+        // Not using `FxHashMap` due to `token::TokenKind: !Eq + !Hash`.
+        modifier: &[(token::TokenKind, i64)],
+    ) {
+        while acc > 0 {
+            if let Some((_, val)) = modifier.iter().find(|(t, _)| *t == self.token.kind) {
+                acc += *val;
+            }
+            if self.token.kind == token::Eof {
+                break;
+            }
+            self.bump();
+        }
+    }
+
+    /// Replace duplicated recovered parameters with `_` pattern to avoid unecessary errors.
+    ///
+    /// This is necessary because at this point we don't know whether we parsed a function with
+    /// anonymous parameters or a function with names but no types. In order to minimize
+    /// unecessary errors, we assume the parameters are in the shape of `fn foo(a, b, c)` where
+    /// the parameters are *names* (so we don't emit errors about not being able to find `b` in
+    /// the local scope), but if we find the same name multiple times, like in `fn foo(i8, i8)`,
+    /// we deduplicate them to not complain about duplicated parameter names.
+    pub(super) fn deduplicate_recovered_params_names(&self, fn_inputs: &mut Vec<Param>) {
+        let mut seen_inputs = FxHashSet::default();
+        for input in fn_inputs.iter_mut() {
+            let opt_ident = if let (PatKind::Ident(_, ident, _), TyKind::Err) = (
+                &input.pat.kind, &input.ty.kind,
+            ) {
+                Some(*ident)
+            } else {
+                None
+            };
+            if let Some(ident) = opt_ident {
+                if seen_inputs.contains(&ident) {
+                    input.pat.kind = PatKind::Wild;
+                }
+                seen_inputs.insert(ident);
+            }
+        }
+    }
+}
diff --git a/src/librustc_parse/parser/expr.rs b/src/librustc_parse/parser/expr.rs
new file mode 100644
index 00000000000..dadb91f8b3c
--- /dev/null
+++ b/src/librustc_parse/parser/expr.rs
@@ -0,0 +1,1963 @@
+use super::{Parser, Restrictions, PrevTokenKind, TokenType, PathStyle, BlockMode};
+use super::{SemiColonMode, SeqSep, TokenExpectType};
+use super::pat::{GateOr, PARAM_EXPECTED};
+use super::diagnostics::Error;
+use crate::maybe_recover_from_interpolated_ty_qpath;
+
+use syntax::ast::{
+    self, DUMMY_NODE_ID, Attribute, AttrStyle, Ident, CaptureBy, BlockCheckMode,
+    Expr, ExprKind, RangeLimits, Label, Movability, IsAsync, Arm, Ty, TyKind,
+    FunctionRetTy, Param, FnDecl, BinOpKind, BinOp, UnOp, Mac, AnonConst, Field, Lit,
+};
+use syntax::token::{self, Token, TokenKind};
+use syntax::print::pprust;
+use syntax::ptr::P;
+use syntax::source_map::{self, Span};
+use syntax::util::classify;
+use syntax::util::literal::LitError;
+use syntax::util::parser::{AssocOp, Fixity, prec_let_scrutinee_needs_par};
+use syntax_pos::symbol::{kw, sym};
+use syntax_pos::Symbol;
+use errors::{PResult, Applicability};
+use std::mem;
+use rustc_data_structures::thin_vec::ThinVec;
+
+/// Possibly accepts an `token::Interpolated` expression (a pre-parsed expression
+/// dropped into the token stream, which happens while parsing the result of
+/// macro expansion). Placement of these is not as complex as I feared it would
+/// be. The important thing is to make sure that lookahead doesn't balk at
+/// `token::Interpolated` tokens.
+macro_rules! maybe_whole_expr {
+    ($p:expr) => {
+        if let token::Interpolated(nt) = &$p.token.kind {
+            match &**nt {
+                token::NtExpr(e) | token::NtLiteral(e) => {
+                    let e = e.clone();
+                    $p.bump();
+                    return Ok(e);
+                }
+                token::NtPath(path) => {
+                    let path = path.clone();
+                    $p.bump();
+                    return Ok($p.mk_expr(
+                        $p.token.span, ExprKind::Path(None, path), ThinVec::new()
+                    ));
+                }
+                token::NtBlock(block) => {
+                    let block = block.clone();
+                    $p.bump();
+                    return Ok($p.mk_expr(
+                        $p.token.span, ExprKind::Block(block, None), ThinVec::new()
+                    ));
+                }
+                // N.B., `NtIdent(ident)` is normalized to `Ident` in `fn bump`.
+                _ => {},
+            };
+        }
+    }
+}
+
+#[derive(Debug)]
+pub(super) enum LhsExpr {
+    NotYetParsed,
+    AttributesParsed(ThinVec<Attribute>),
+    AlreadyParsed(P<Expr>),
+}
+
+impl From<Option<ThinVec<Attribute>>> for LhsExpr {
+    /// Converts `Some(attrs)` into `LhsExpr::AttributesParsed(attrs)`
+    /// and `None` into `LhsExpr::NotYetParsed`.
+    ///
+    /// This conversion does not allocate.
+    fn from(o: Option<ThinVec<Attribute>>) -> Self {
+        if let Some(attrs) = o {
+            LhsExpr::AttributesParsed(attrs)
+        } else {
+            LhsExpr::NotYetParsed
+        }
+    }
+}
+
+impl From<P<Expr>> for LhsExpr {
+    /// Converts the `expr: P<Expr>` into `LhsExpr::AlreadyParsed(expr)`.
+    ///
+    /// This conversion does not allocate.
+    fn from(expr: P<Expr>) -> Self {
+        LhsExpr::AlreadyParsed(expr)
+    }
+}
+
+impl<'a> Parser<'a> {
+    /// Parses an expression.
+    #[inline]
+    pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
+        self.parse_expr_res(Restrictions::empty(), None)
+    }
+
+    fn parse_paren_expr_seq(&mut self) -> PResult<'a, Vec<P<Expr>>> {
+        self.parse_paren_comma_seq(|p| {
+            match p.parse_expr() {
+                Ok(expr) => Ok(expr),
+                Err(mut err) => match p.token.kind {
+                    token::Ident(name, false)
+                    if name == kw::Underscore && p.look_ahead(1, |t| {
+                        t == &token::Comma
+                    }) => {
+                        // Special-case handling of `foo(_, _, _)`
+                        err.emit();
+                        let sp = p.token.span;
+                        p.bump();
+                        Ok(p.mk_expr(sp, ExprKind::Err, ThinVec::new()))
+                    }
+                    _ => Err(err),
+                },
+            }
+        }).map(|(r, _)| r)
+    }
+
+    /// Parses an expression, subject to the given restrictions.
+    #[inline]
+    pub(super) fn parse_expr_res(
+        &mut self,
+        r: Restrictions,
+        already_parsed_attrs: Option<ThinVec<Attribute>>
+    ) -> PResult<'a, P<Expr>> {
+        self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs))
+    }
+
+    /// Parses an associative expression.
+    ///
+    /// This parses an expression accounting for associativity and precedence of the operators in
+    /// the expression.
+    #[inline]
+    fn parse_assoc_expr(
+        &mut self,
+        already_parsed_attrs: Option<ThinVec<Attribute>>,
+    ) -> PResult<'a, P<Expr>> {
+        self.parse_assoc_expr_with(0, already_parsed_attrs.into())
+    }
+
+    /// Parses an associative expression with operators of at least `min_prec` precedence.
+    pub(super) fn parse_assoc_expr_with(
+        &mut self,
+        min_prec: usize,
+        lhs: LhsExpr,
+    ) -> PResult<'a, P<Expr>> {
+        let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs {
+            expr
+        } else {
+            let attrs = match lhs {
+                LhsExpr::AttributesParsed(attrs) => Some(attrs),
+                _ => None,
+            };
+            if [token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token.kind) {
+                return self.parse_prefix_range_expr(attrs);
+            } else {
+                self.parse_prefix_expr(attrs)?
+            }
+        };
+        let last_type_ascription_set = self.last_type_ascription.is_some();
+
+        match (self.expr_is_complete(&lhs), AssocOp::from_token(&self.token)) {
+            (true, None) => {
+                self.last_type_ascription = None;
+                // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
+                return Ok(lhs);
+            }
+            (false, _) => {} // continue parsing the expression
+            // An exhaustive check is done in the following block, but these are checked first
+            // because they *are* ambiguous but also reasonable looking incorrect syntax, so we
+            // want to keep their span info to improve diagnostics in these cases in a later stage.
+            (true, Some(AssocOp::Multiply)) | // `{ 42 } *foo = bar;` or `{ 42 } * 3`
+            (true, Some(AssocOp::Subtract)) | // `{ 42 } -5`
+            (true, Some(AssocOp::LAnd)) | // `{ 42 } &&x` (#61475)
+            (true, Some(AssocOp::Add)) // `{ 42 } + 42
+            // If the next token is a keyword, then the tokens above *are* unambiguously incorrect:
+            // `if x { a } else { b } && if y { c } else { d }`
+            if !self.look_ahead(1, |t| t.is_reserved_ident()) => {
+                self.last_type_ascription = None;
+                // These cases are ambiguous and can't be identified in the parser alone
+                let sp = self.sess.source_map().start_point(self.token.span);
+                self.sess.ambiguous_block_expr_parse.borrow_mut().insert(sp, lhs.span);
+                return Ok(lhs);
+            }
+            (true, Some(ref op)) if !op.can_continue_expr_unambiguously() => {
+                self.last_type_ascription = None;
+                return Ok(lhs);
+            }
+            (true, Some(_)) => {
+                // We've found an expression that would be parsed as a statement, but the next
+                // token implies this should be parsed as an expression.
+                // For example: `if let Some(x) = x { x } else { 0 } / 2`
+                let mut err = self.struct_span_err(self.token.span, &format!(
+                    "expected expression, found `{}`",
+                    pprust::token_to_string(&self.token),
+                ));
+                err.span_label(self.token.span, "expected expression");
+                self.sess.expr_parentheses_needed(
+                    &mut err,
+                    lhs.span,
+                    Some(pprust::expr_to_string(&lhs),
+                ));
+                err.emit();
+            }
+        }
+        self.expected_tokens.push(TokenType::Operator);
+        while let Some(op) = AssocOp::from_token(&self.token) {
+
+            // Adjust the span for interpolated LHS to point to the `$lhs` token and not to what
+            // it refers to. Interpolated identifiers are unwrapped early and never show up here
+            // as `PrevTokenKind::Interpolated` so if LHS is a single identifier we always process
+            // it as "interpolated", it doesn't change the answer for non-interpolated idents.
+            let lhs_span = match (self.prev_token_kind, &lhs.kind) {
+                (PrevTokenKind::Interpolated, _) => self.prev_span,
+                (PrevTokenKind::Ident, &ExprKind::Path(None, ref path))
+                    if path.segments.len() == 1 => self.prev_span,
+                _ => lhs.span,
+            };
+
+            let cur_op_span = self.token.span;
+            let restrictions = if op.is_assign_like() {
+                self.restrictions & Restrictions::NO_STRUCT_LITERAL
+            } else {
+                self.restrictions
+            };
+            let prec = op.precedence();
+            if prec < min_prec {
+                break;
+            }
+            // Check for deprecated `...` syntax
+            if self.token == token::DotDotDot && op == AssocOp::DotDotEq {
+                self.err_dotdotdot_syntax(self.token.span);
+            }
+
+            if self.token == token::LArrow {
+                self.err_larrow_operator(self.token.span);
+            }
+
+            self.bump();
+            if op.is_comparison() {
+                if let Some(expr) = self.check_no_chained_comparison(&lhs, &op)? {
+                    return Ok(expr);
+                }
+            }
+            // Special cases:
+            if op == AssocOp::As {
+                lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Cast)?;
+                continue
+            } else if op == AssocOp::Colon {
+                let maybe_path = self.could_ascription_be_path(&lhs.kind);
+                self.last_type_ascription = Some((self.prev_span, maybe_path));
+
+                lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Type)?;
+                self.sess.gated_spans.gate(sym::type_ascription, lhs.span);
+                continue
+            } else if op == AssocOp::DotDot || op == AssocOp::DotDotEq {
+                // If we didn’t have to handle `x..`/`x..=`, it would be pretty easy to
+                // generalise it to the Fixity::None code.
+                //
+                // We have 2 alternatives here: `x..y`/`x..=y` and `x..`/`x..=` The other
+                // two variants are handled with `parse_prefix_range_expr` call above.
+                let rhs = if self.is_at_start_of_range_notation_rhs() {
+                    Some(self.parse_assoc_expr_with(prec + 1, LhsExpr::NotYetParsed)?)
+                } else {
+                    None
+                };
+                let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs {
+                    x.span
+                } else {
+                    cur_op_span
+                });
+                let limits = if op == AssocOp::DotDot {
+                    RangeLimits::HalfOpen
+                } else {
+                    RangeLimits::Closed
+                };
+
+                let r = self.mk_range(Some(lhs), rhs, limits)?;
+                lhs = self.mk_expr(lhs_span.to(rhs_span), r, ThinVec::new());
+                break
+            }
+
+            let fixity = op.fixity();
+            let prec_adjustment = match fixity {
+                Fixity::Right => 0,
+                Fixity::Left => 1,
+                // We currently have no non-associative operators that are not handled above by
+                // the special cases. The code is here only for future convenience.
+                Fixity::None => 1,
+            };
+            let rhs = self.with_res(
+                restrictions - Restrictions::STMT_EXPR,
+                |this| this.parse_assoc_expr_with(prec + prec_adjustment, LhsExpr::NotYetParsed)
+            )?;
+
+            // Make sure that the span of the parent node is larger than the span of lhs and rhs,
+            // including the attributes.
+            let lhs_span = lhs
+                .attrs
+                .iter()
+                .filter(|a| a.style == AttrStyle::Outer)
+                .next()
+                .map_or(lhs_span, |a| a.span);
+            let span = lhs_span.to(rhs.span);
+            lhs = match op {
+                AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |
+                AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor |
+                AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight |
+                AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual |
+                AssocOp::Greater | AssocOp::GreaterEqual => {
+                    let ast_op = op.to_ast_binop().unwrap();
+                    let binary = self.mk_binary(source_map::respan(cur_op_span, ast_op), lhs, rhs);
+                    self.mk_expr(span, binary, ThinVec::new())
+                }
+                AssocOp::Assign => self.mk_expr(span, ExprKind::Assign(lhs, rhs), ThinVec::new()),
+                AssocOp::AssignOp(k) => {
+                    let aop = match k {
+                        token::Plus =>    BinOpKind::Add,
+                        token::Minus =>   BinOpKind::Sub,
+                        token::Star =>    BinOpKind::Mul,
+                        token::Slash =>   BinOpKind::Div,
+                        token::Percent => BinOpKind::Rem,
+                        token::Caret =>   BinOpKind::BitXor,
+                        token::And =>     BinOpKind::BitAnd,
+                        token::Or =>      BinOpKind::BitOr,
+                        token::Shl =>     BinOpKind::Shl,
+                        token::Shr =>     BinOpKind::Shr,
+                    };
+                    let aopexpr = self.mk_assign_op(source_map::respan(cur_op_span, aop), lhs, rhs);
+                    self.mk_expr(span, aopexpr, ThinVec::new())
+                }
+                AssocOp::As | AssocOp::Colon | AssocOp::DotDot | AssocOp::DotDotEq => {
+                    self.bug("AssocOp should have been handled by special case")
+                }
+            };
+
+            if let Fixity::None = fixity { break }
+        }
+        if last_type_ascription_set {
+            self.last_type_ascription = None;
+        }
+        Ok(lhs)
+    }
+
+    /// Checks if this expression is a successfully parsed statement.
+    fn expr_is_complete(&self, e: &Expr) -> bool {
+        self.restrictions.contains(Restrictions::STMT_EXPR) &&
+            !classify::expr_requires_semi_to_be_stmt(e)
+    }
+
+    fn is_at_start_of_range_notation_rhs(&self) -> bool {
+        if self.token.can_begin_expr() {
+            // Parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
+            if self.token == token::OpenDelim(token::Brace) {
+                return !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
+            }
+            true
+        } else {
+            false
+        }
+    }
+
+    /// Parses prefix-forms of range notation: `..expr`, `..`, `..=expr`.
+    fn parse_prefix_range_expr(
+        &mut self,
+        already_parsed_attrs: Option<ThinVec<Attribute>>
+    ) -> PResult<'a, P<Expr>> {
+        // Check for deprecated `...` syntax.
+        if self.token == token::DotDotDot {
+            self.err_dotdotdot_syntax(self.token.span);
+        }
+
+        debug_assert!([token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token.kind),
+                      "parse_prefix_range_expr: token {:?} is not DotDot/DotDotEq",
+                      self.token);
+        let tok = self.token.clone();
+        let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
+        let lo = self.token.span;
+        let mut hi = self.token.span;
+        self.bump();
+        let opt_end = if self.is_at_start_of_range_notation_rhs() {
+            // RHS must be parsed with more associativity than the dots.
+            let next_prec = AssocOp::from_token(&tok).unwrap().precedence() + 1;
+            Some(self.parse_assoc_expr_with(next_prec, LhsExpr::NotYetParsed)
+                .map(|x| {
+                    hi = x.span;
+                    x
+                })?)
+        } else {
+            None
+        };
+        let limits = if tok == token::DotDot {
+            RangeLimits::HalfOpen
+        } else {
+            RangeLimits::Closed
+        };
+
+        let r = self.mk_range(None, opt_end, limits)?;
+        Ok(self.mk_expr(lo.to(hi), r, attrs))
+    }
+
+    /// Parses a prefix-unary-operator expr.
+    fn parse_prefix_expr(
+        &mut self,
+        already_parsed_attrs: Option<ThinVec<Attribute>>
+    ) -> PResult<'a, P<Expr>> {
+        let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
+        let lo = self.token.span;
+        // Note: when adding new unary operators, don't forget to adjust TokenKind::can_begin_expr()
+        let (hi, ex) = match self.token.kind {
+            token::Not => {
+                self.bump();
+                let e = self.parse_prefix_expr(None);
+                let (span, e) = self.interpolated_or_expr_span(e)?;
+                (lo.to(span), self.mk_unary(UnOp::Not, e))
+            }
+            // Suggest `!` for bitwise negation when encountering a `~`
+            token::Tilde => {
+                self.bump();
+                let e = self.parse_prefix_expr(None);
+                let (span, e) = self.interpolated_or_expr_span(e)?;
+                let span_of_tilde = lo;
+                self.struct_span_err(span_of_tilde, "`~` cannot be used as a unary operator")
+                    .span_suggestion_short(
+                        span_of_tilde,
+                        "use `!` to perform bitwise not",
+                        "!".to_owned(),
+                        Applicability::MachineApplicable
+                    )
+                    .emit();
+                (lo.to(span), self.mk_unary(UnOp::Not, e))
+            }
+            token::BinOp(token::Minus) => {
+                self.bump();
+                let e = self.parse_prefix_expr(None);
+                let (span, e) = self.interpolated_or_expr_span(e)?;
+                (lo.to(span), self.mk_unary(UnOp::Neg, e))
+            }
+            token::BinOp(token::Star) => {
+                self.bump();
+                let e = self.parse_prefix_expr(None);
+                let (span, e) = self.interpolated_or_expr_span(e)?;
+                (lo.to(span), self.mk_unary(UnOp::Deref, e))
+            }
+            token::BinOp(token::And) | token::AndAnd => {
+                self.expect_and()?;
+                let m = self.parse_mutability();
+                let e = self.parse_prefix_expr(None);
+                let (span, e) = self.interpolated_or_expr_span(e)?;
+                (lo.to(span), ExprKind::AddrOf(m, e))
+            }
+            token::Ident(..) if self.token.is_keyword(kw::Box) => {
+                self.bump();
+                let e = self.parse_prefix_expr(None);
+                let (span, e) = self.interpolated_or_expr_span(e)?;
+                let span = lo.to(span);
+                self.sess.gated_spans.gate(sym::box_syntax, span);
+                (span, ExprKind::Box(e))
+            }
+            token::Ident(..) if self.token.is_ident_named(sym::not) => {
+                // `not` is just an ordinary identifier in Rust-the-language,
+                // but as `rustc`-the-compiler, we can issue clever diagnostics
+                // for confused users who really want to say `!`
+                let token_cannot_continue_expr = |t: &Token| match t.kind {
+                    // These tokens can start an expression after `!`, but
+                    // can't continue an expression after an ident
+                    token::Ident(name, is_raw) => token::ident_can_begin_expr(name, t.span, is_raw),
+                    token::Literal(..) | token::Pound => true,
+                    _ => t.is_whole_expr(),
+                };
+                let cannot_continue_expr = self.look_ahead(1, token_cannot_continue_expr);
+                if cannot_continue_expr {
+                    self.bump();
+                    // Emit the error ...
+                    self.struct_span_err(
+                        self.token.span,
+                        &format!("unexpected {} after identifier",self.this_token_descr())
+                    )
+                    .span_suggestion_short(
+                        // Span the `not` plus trailing whitespace to avoid
+                        // trailing whitespace after the `!` in our suggestion
+                        self.sess.source_map()
+                            .span_until_non_whitespace(lo.to(self.token.span)),
+                        "use `!` to perform logical negation",
+                        "!".to_owned(),
+                        Applicability::MachineApplicable
+                    )
+                    .emit();
+                    // —and recover! (just as if we were in the block
+                    // for the `token::Not` arm)
+                    let e = self.parse_prefix_expr(None);
+                    let (span, e) = self.interpolated_or_expr_span(e)?;
+                    (lo.to(span), self.mk_unary(UnOp::Not, e))
+                } else {
+                    return self.parse_dot_or_call_expr(Some(attrs));
+                }
+            }
+            _ => { return self.parse_dot_or_call_expr(Some(attrs)); }
+        };
+        return Ok(self.mk_expr(lo.to(hi), ex, attrs));
+    }
+
+    /// Returns the span of expr, if it was not interpolated or the span of the interpolated token.
+    fn interpolated_or_expr_span(
+        &self,
+        expr: PResult<'a, P<Expr>>,
+    ) -> PResult<'a, (Span, P<Expr>)> {
+        expr.map(|e| {
+            if self.prev_token_kind == PrevTokenKind::Interpolated {
+                (self.prev_span, e)
+            } else {
+                (e.span, e)
+            }
+        })
+    }
+
+    fn parse_assoc_op_cast(&mut self, lhs: P<Expr>, lhs_span: Span,
+                           expr_kind: fn(P<Expr>, P<Ty>) -> ExprKind)
+                           -> PResult<'a, P<Expr>> {
+        let mk_expr = |this: &mut Self, rhs: P<Ty>| {
+            this.mk_expr(lhs_span.to(rhs.span), expr_kind(lhs, rhs), ThinVec::new())
+        };
+
+        // Save the state of the parser before parsing type normally, in case there is a
+        // LessThan comparison after this cast.
+        let parser_snapshot_before_type = self.clone();
+        match self.parse_ty_no_plus() {
+            Ok(rhs) => {
+                Ok(mk_expr(self, rhs))
+            }
+            Err(mut type_err) => {
+                // Rewind to before attempting to parse the type with generics, to recover
+                // from situations like `x as usize < y` in which we first tried to parse
+                // `usize < y` as a type with generic arguments.
+                let parser_snapshot_after_type = self.clone();
+                mem::replace(self, parser_snapshot_before_type);
+
+                match self.parse_path(PathStyle::Expr) {
+                    Ok(path) => {
+                        let (op_noun, op_verb) = match self.token.kind {
+                            token::Lt => ("comparison", "comparing"),
+                            token::BinOp(token::Shl) => ("shift", "shifting"),
+                            _ => {
+                                // We can end up here even without `<` being the next token, for
+                                // example because `parse_ty_no_plus` returns `Err` on keywords,
+                                // but `parse_path` returns `Ok` on them due to error recovery.
+                                // Return original error and parser state.
+                                mem::replace(self, parser_snapshot_after_type);
+                                return Err(type_err);
+                            }
+                        };
+
+                        // Successfully parsed the type path leaving a `<` yet to parse.
+                        type_err.cancel();
+
+                        // Report non-fatal diagnostics, keep `x as usize` as an expression
+                        // in AST and continue parsing.
+                        let msg = format!(
+                            "`<` is interpreted as a start of generic arguments for `{}`, not a {}",
+                            pprust::path_to_string(&path),
+                            op_noun,
+                        );
+                        let span_after_type = parser_snapshot_after_type.token.span;
+                        let expr = mk_expr(self, P(Ty {
+                            span: path.span,
+                            kind: TyKind::Path(None, path),
+                            id: DUMMY_NODE_ID,
+                        }));
+
+                        let expr_str = self.span_to_snippet(expr.span)
+                            .unwrap_or_else(|_| pprust::expr_to_string(&expr));
+
+                        self.struct_span_err(self.token.span, &msg)
+                            .span_label(
+                                self.look_ahead(1, |t| t.span).to(span_after_type),
+                                "interpreted as generic arguments"
+                            )
+                            .span_label(self.token.span, format!("not interpreted as {}", op_noun))
+                            .span_suggestion(
+                                expr.span,
+                                &format!("try {} the cast value", op_verb),
+                                format!("({})", expr_str),
+                                Applicability::MachineApplicable,
+                            )
+                            .emit();
+
+                        Ok(expr)
+                    }
+                    Err(mut path_err) => {
+                        // Couldn't parse as a path, return original error and parser state.
+                        path_err.cancel();
+                        mem::replace(self, parser_snapshot_after_type);
+                        Err(type_err)
+                    }
+                }
+            }
+        }
+    }
+
+    /// Parses `a.b` or `a(13)` or `a[4]` or just `a`.
+    fn parse_dot_or_call_expr(
+        &mut self,
+        already_parsed_attrs: Option<ThinVec<Attribute>>,
+    ) -> PResult<'a, P<Expr>> {
+        let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
+
+        let b = self.parse_bottom_expr();
+        let (span, b) = self.interpolated_or_expr_span(b)?;
+        self.parse_dot_or_call_expr_with(b, span, attrs)
+    }
+
+    pub(super) fn parse_dot_or_call_expr_with(
+        &mut self,
+        e0: P<Expr>,
+        lo: Span,
+        mut attrs: ThinVec<Attribute>,
+    ) -> PResult<'a, P<Expr>> {
+        // Stitch the list of outer attributes onto the return value.
+        // A little bit ugly, but the best way given the current code
+        // structure
+        self.parse_dot_or_call_expr_with_(e0, lo).map(|expr|
+            expr.map(|mut expr| {
+                attrs.extend::<Vec<_>>(expr.attrs.into());
+                expr.attrs = attrs;
+                match expr.kind {
+                    ExprKind::If(..) if !expr.attrs.is_empty() => {
+                        // Just point to the first attribute in there...
+                        let span = expr.attrs[0].span;
+                        self.span_err(span, "attributes are not yet allowed on `if` expressions");
+                    }
+                    _ => {}
+                }
+                expr
+            })
+        )
+    }
+
+    fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
+        let mut e = e0;
+        let mut hi;
+        loop {
+            // expr?
+            while self.eat(&token::Question) {
+                let hi = self.prev_span;
+                e = self.mk_expr(lo.to(hi), ExprKind::Try(e), ThinVec::new());
+            }
+
+            // expr.f
+            if self.eat(&token::Dot) {
+                match self.token.kind {
+                    token::Ident(..) => {
+                        e = self.parse_dot_suffix(e, lo)?;
+                    }
+                    token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) => {
+                        let span = self.token.span;
+                        self.bump();
+                        let field = ExprKind::Field(e, Ident::new(symbol, span));
+                        e = self.mk_expr(lo.to(span), field, ThinVec::new());
+
+                        self.expect_no_suffix(span, "a tuple index", suffix);
+                    }
+                    token::Literal(token::Lit { kind: token::Float, symbol, .. }) => {
+                      self.bump();
+                      let fstr = symbol.as_str();
+                      let msg = format!("unexpected token: `{}`", symbol);
+                      let mut err = self.diagnostic().struct_span_err(self.prev_span, &msg);
+                      err.span_label(self.prev_span, "unexpected token");
+                      if fstr.chars().all(|x| "0123456789.".contains(x)) {
+                          let float = match fstr.parse::<f64>().ok() {
+                              Some(f) => f,
+                              None => continue,
+                          };
+                          let sugg = pprust::to_string(|s| {
+                              s.popen();
+                              s.print_expr(&e);
+                              s.s.word( ".");
+                              s.print_usize(float.trunc() as usize);
+                              s.pclose();
+                              s.s.word(".");
+                              s.s.word(fstr.splitn(2, ".").last().unwrap().to_string())
+                          });
+                          err.span_suggestion(
+                              lo.to(self.prev_span),
+                              "try parenthesizing the first index",
+                              sugg,
+                              Applicability::MachineApplicable
+                          );
+                      }
+                      return Err(err);
+
+                    }
+                    _ => {
+                        // FIXME Could factor this out into non_fatal_unexpected or something.
+                        let actual = self.this_token_to_string();
+                        self.span_err(self.token.span, &format!("unexpected token: `{}`", actual));
+                    }
+                }
+                continue;
+            }
+            if self.expr_is_complete(&e) { break; }
+            match self.token.kind {
+                // expr(...)
+                token::OpenDelim(token::Paren) => {
+                    let seq = self.parse_paren_expr_seq().map(|es| {
+                        let nd = self.mk_call(e, es);
+                        let hi = self.prev_span;
+                        self.mk_expr(lo.to(hi), nd, ThinVec::new())
+                    });
+                    e = self.recover_seq_parse_error(token::Paren, lo, seq);
+                }
+
+                // expr[...]
+                // Could be either an index expression or a slicing expression.
+                token::OpenDelim(token::Bracket) => {
+                    self.bump();
+                    let ix = self.parse_expr()?;
+                    hi = self.token.span;
+                    self.expect(&token::CloseDelim(token::Bracket))?;
+                    let index = self.mk_index(e, ix);
+                    e = self.mk_expr(lo.to(hi), index, ThinVec::new())
+                }
+                _ => return Ok(e)
+            }
+        }
+        return Ok(e);
+    }
+
+    /// Assuming we have just parsed `.`, continue parsing into an expression.
+    fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
+        if self.token.span.rust_2018() && self.eat_keyword(kw::Await) {
+            return self.mk_await_expr(self_arg, lo);
+        }
+
+        let segment = self.parse_path_segment(PathStyle::Expr)?;
+        self.check_trailing_angle_brackets(&segment, token::OpenDelim(token::Paren));
+
+        Ok(match self.token.kind {
+            token::OpenDelim(token::Paren) => {
+                // Method call `expr.f()`
+                let mut args = self.parse_paren_expr_seq()?;
+                args.insert(0, self_arg);
+
+                let span = lo.to(self.prev_span);
+                self.mk_expr(span, ExprKind::MethodCall(segment, args), ThinVec::new())
+            }
+            _ => {
+                // Field access `expr.f`
+                if let Some(args) = segment.args {
+                    self.span_err(args.span(),
+                                  "field expressions may not have generic arguments");
+                }
+
+                let span = lo.to(self.prev_span);
+                self.mk_expr(span, ExprKind::Field(self_arg, segment.ident), ThinVec::new())
+            }
+        })
+    }
+
+    /// At the bottom (top?) of the precedence hierarchy,
+    /// Parses things like parenthesized exprs, macros, `return`, etc.
+    ///
+    /// N.B., this does not parse outer attributes, and is private because it only works
+    /// correctly if called from `parse_dot_or_call_expr()`.
+    fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> {
+        maybe_recover_from_interpolated_ty_qpath!(self, true);
+        maybe_whole_expr!(self);
+
+        // Outer attributes are already parsed and will be
+        // added to the return value after the fact.
+        //
+        // Therefore, prevent sub-parser from parsing
+        // attributes by giving them a empty "already-parsed" list.
+        let mut attrs = ThinVec::new();
+
+        let lo = self.token.span;
+        let mut hi = self.token.span;
+
+        let ex: ExprKind;
+
+        macro_rules! parse_lit {
+            () => {
+                match self.parse_lit() {
+                    Ok(literal) => {
+                        hi = self.prev_span;
+                        ex = ExprKind::Lit(literal);
+                    }
+                    Err(mut err) => {
+                        err.cancel();
+                        return Err(self.expected_expression_found());
+                    }
+                }
+            }
+        }
+
+        // Note: when adding new syntax here, don't forget to adjust `TokenKind::can_begin_expr()`.
+        match self.token.kind {
+            // This match arm is a special-case of the `_` match arm below and
+            // could be removed without changing functionality, but it's faster
+            // to have it here, especially for programs with large constants.
+            token::Literal(_) => {
+                parse_lit!()
+            }
+            token::OpenDelim(token::Paren) => {
+                self.bump();
+
+                attrs.extend(self.parse_inner_attributes()?);
+
+                // `(e)` is parenthesized `e`.
+                // `(e,)` is a tuple with only one field, `e`.
+                let mut es = vec![];
+                let mut trailing_comma = false;
+                let mut recovered = false;
+                while self.token != token::CloseDelim(token::Paren) {
+                    es.push(match self.parse_expr() {
+                        Ok(es) => es,
+                        Err(mut err) => {
+                            // Recover from parse error in tuple list.
+                            match self.token.kind {
+                                token::Ident(name, false)
+                                if name == kw::Underscore && self.look_ahead(1, |t| {
+                                    t == &token::Comma
+                                }) => {
+                                    // Special-case handling of `Foo<(_, _, _)>`
+                                    err.emit();
+                                    let sp = self.token.span;
+                                    self.bump();
+                                    self.mk_expr(sp, ExprKind::Err, ThinVec::new())
+                                }
+                                _ => return Ok(
+                                    self.recover_seq_parse_error(token::Paren, lo, Err(err)),
+                                ),
+                            }
+                        }
+                    });
+                    recovered = self.expect_one_of(
+                        &[],
+                        &[token::Comma, token::CloseDelim(token::Paren)],
+                    )?;
+                    if self.eat(&token::Comma) {
+                        trailing_comma = true;
+                    } else {
+                        trailing_comma = false;
+                        break;
+                    }
+                }
+                if !recovered {
+                    self.bump();
+                }
+
+                hi = self.prev_span;
+                ex = if es.len() == 1 && !trailing_comma {
+                    ExprKind::Paren(es.into_iter().nth(0).unwrap())
+                } else {
+                    ExprKind::Tup(es)
+                };
+            }
+            token::OpenDelim(token::Brace) => {
+                return self.parse_block_expr(None, lo, BlockCheckMode::Default, attrs);
+            }
+            token::BinOp(token::Or) | token::OrOr => {
+                return self.parse_closure_expr(attrs);
+            }
+            token::OpenDelim(token::Bracket) => {
+                self.bump();
+
+                attrs.extend(self.parse_inner_attributes()?);
+
+                if self.eat(&token::CloseDelim(token::Bracket)) {
+                    // Empty vector
+                    ex = ExprKind::Array(Vec::new());
+                } else {
+                    // Non-empty vector
+                    let first_expr = self.parse_expr()?;
+                    if self.eat(&token::Semi) {
+                        // Repeating array syntax: `[ 0; 512 ]`
+                        let count = AnonConst {
+                            id: DUMMY_NODE_ID,
+                            value: self.parse_expr()?,
+                        };
+                        self.expect(&token::CloseDelim(token::Bracket))?;
+                        ex = ExprKind::Repeat(first_expr, count);
+                    } else if self.eat(&token::Comma) {
+                        // Vector with two or more elements
+                        let remaining_exprs = self.parse_seq_to_end(
+                            &token::CloseDelim(token::Bracket),
+                            SeqSep::trailing_allowed(token::Comma),
+                            |p| Ok(p.parse_expr()?)
+                        )?;
+                        let mut exprs = vec![first_expr];
+                        exprs.extend(remaining_exprs);
+                        ex = ExprKind::Array(exprs);
+                    } else {
+                        // Vector with one element
+                        self.expect(&token::CloseDelim(token::Bracket))?;
+                        ex = ExprKind::Array(vec![first_expr]);
+                    }
+                }
+                hi = self.prev_span;
+            }
+            _ => {
+                if self.eat_lt() {
+                    let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
+                    hi = path.span;
+                    return Ok(self.mk_expr(lo.to(hi), ExprKind::Path(Some(qself), path), attrs));
+                }
+                if self.token.is_path_start() {
+                    let path = self.parse_path(PathStyle::Expr)?;
+
+                    // `!`, as an operator, is prefix, so we know this isn't that.
+                    if self.eat(&token::Not) {
+                        // MACRO INVOCATION expression
+                        let (delim, tts) = self.expect_delimited_token_tree()?;
+                        hi = self.prev_span;
+                        ex = ExprKind::Mac(Mac {
+                            path,
+                            tts,
+                            delim,
+                            span: lo.to(hi),
+                            prior_type_ascription: self.last_type_ascription,
+                        });
+                    } else if self.check(&token::OpenDelim(token::Brace)) {
+                        if let Some(expr) = self.maybe_parse_struct_expr(lo, &path, &attrs) {
+                            return expr;
+                        } else {
+                            hi = path.span;
+                            ex = ExprKind::Path(None, path);
+                        }
+                    } else {
+                        hi = path.span;
+                        ex = ExprKind::Path(None, path);
+                    }
+
+                    let expr = self.mk_expr(lo.to(hi), ex, attrs);
+                    return self.maybe_recover_from_bad_qpath(expr, true);
+                }
+                if self.check_keyword(kw::Move) || self.check_keyword(kw::Static) {
+                    return self.parse_closure_expr(attrs);
+                }
+                if self.eat_keyword(kw::If) {
+                    return self.parse_if_expr(attrs);
+                }
+                if self.eat_keyword(kw::For) {
+                    let lo = self.prev_span;
+                    return self.parse_for_expr(None, lo, attrs);
+                }
+                if self.eat_keyword(kw::While) {
+                    let lo = self.prev_span;
+                    return self.parse_while_expr(None, lo, attrs);
+                }
+                if let Some(label) = self.eat_label() {
+                    let lo = label.ident.span;
+                    self.expect(&token::Colon)?;
+                    if self.eat_keyword(kw::While) {
+                        return self.parse_while_expr(Some(label), lo, attrs)
+                    }
+                    if self.eat_keyword(kw::For) {
+                        return self.parse_for_expr(Some(label), lo, attrs)
+                    }
+                    if self.eat_keyword(kw::Loop) {
+                        return self.parse_loop_expr(Some(label), lo, attrs)
+                    }
+                    if self.token == token::OpenDelim(token::Brace) {
+                        return self.parse_block_expr(Some(label),
+                                                     lo,
+                                                     BlockCheckMode::Default,
+                                                     attrs);
+                    }
+                    let msg = "expected `while`, `for`, `loop` or `{` after a label";
+                    let mut err = self.fatal(msg);
+                    err.span_label(self.token.span, msg);
+                    return Err(err);
+                }
+                if self.eat_keyword(kw::Loop) {
+                    let lo = self.prev_span;
+                    return self.parse_loop_expr(None, lo, attrs);
+                }
+                if self.eat_keyword(kw::Continue) {
+                    let label = self.eat_label();
+                    let ex = ExprKind::Continue(label);
+                    let hi = self.prev_span;
+                    return Ok(self.mk_expr(lo.to(hi), ex, attrs));
+                }
+                if self.eat_keyword(kw::Match) {
+                    let match_sp = self.prev_span;
+                    return self.parse_match_expr(attrs).map_err(|mut err| {
+                        err.span_label(match_sp, "while parsing this match expression");
+                        err
+                    });
+                }
+                if self.eat_keyword(kw::Unsafe) {
+                    return self.parse_block_expr(
+                        None,
+                        lo,
+                        BlockCheckMode::Unsafe(ast::UserProvided),
+                        attrs);
+                }
+                if self.is_do_catch_block() {
+                    let mut db = self.fatal("found removed `do catch` syntax");
+                    db.help("following RFC #2388, the new non-placeholder syntax is `try`");
+                    return Err(db);
+                }
+                if self.is_try_block() {
+                    let lo = self.token.span;
+                    assert!(self.eat_keyword(kw::Try));
+                    return self.parse_try_block(lo, attrs);
+                }
+
+                // `Span::rust_2018()` is somewhat expensive; don't get it repeatedly.
+                let is_span_rust_2018 = self.token.span.rust_2018();
+                if is_span_rust_2018 && self.check_keyword(kw::Async) {
+                    return if self.is_async_block() { // Check for `async {` and `async move {`.
+                        self.parse_async_block(attrs)
+                    } else {
+                        self.parse_closure_expr(attrs)
+                    };
+                }
+                if self.eat_keyword(kw::Return) {
+                    if self.token.can_begin_expr() {
+                        let e = self.parse_expr()?;
+                        hi = e.span;
+                        ex = ExprKind::Ret(Some(e));
+                    } else {
+                        ex = ExprKind::Ret(None);
+                    }
+                } else if self.eat_keyword(kw::Break) {
+                    let label = self.eat_label();
+                    let e = if self.token.can_begin_expr()
+                               && !(self.token == token::OpenDelim(token::Brace)
+                                    && self.restrictions.contains(
+                                           Restrictions::NO_STRUCT_LITERAL)) {
+                        Some(self.parse_expr()?)
+                    } else {
+                        None
+                    };
+                    ex = ExprKind::Break(label, e);
+                    hi = self.prev_span;
+                } else if self.eat_keyword(kw::Yield) {
+                    if self.token.can_begin_expr() {
+                        let e = self.parse_expr()?;
+                        hi = e.span;
+                        ex = ExprKind::Yield(Some(e));
+                    } else {
+                        ex = ExprKind::Yield(None);
+                    }
+
+                    let span = lo.to(hi);
+                    self.sess.gated_spans.gate(sym::generators, span);
+                } else if self.eat_keyword(kw::Let) {
+                    return self.parse_let_expr(attrs);
+                } else if is_span_rust_2018 && self.eat_keyword(kw::Await) {
+                    let (await_hi, e_kind) = self.parse_incorrect_await_syntax(lo, self.prev_span)?;
+                    hi = await_hi;
+                    ex = e_kind;
+                } else {
+                    if !self.unclosed_delims.is_empty() && self.check(&token::Semi) {
+                        // Don't complain about bare semicolons after unclosed braces
+                        // recovery in order to keep the error count down. Fixing the
+                        // delimiters will possibly also fix the bare semicolon found in
+                        // expression context. For example, silence the following error:
+                        //
+                        //     error: expected expression, found `;`
+                        //      --> file.rs:2:13
+                        //       |
+                        //     2 |     foo(bar(;
+                        //       |             ^ expected expression
+                        self.bump();
+                        return Ok(self.mk_expr(self.token.span, ExprKind::Err, ThinVec::new()));
+                    }
+                    parse_lit!()
+                }
+            }
+        }
+
+        let expr = self.mk_expr(lo.to(hi), ex, attrs);
+        self.maybe_recover_from_bad_qpath(expr, true)
+    }
+
+    /// Matches `lit = true | false | token_lit`.
+    pub(super) fn parse_lit(&mut self) -> PResult<'a, Lit> {
+        let mut recovered = None;
+        if self.token == token::Dot {
+            // Attempt to recover `.4` as `0.4`.
+            recovered = self.look_ahead(1, |next_token| {
+                if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix })
+                        = next_token.kind {
+                    if self.token.span.hi() == next_token.span.lo() {
+                        let s = String::from("0.") + &symbol.as_str();
+                        let kind = TokenKind::lit(token::Float, Symbol::intern(&s), suffix);
+                        return Some(Token::new(kind, self.token.span.to(next_token.span)));
+                    }
+                }
+                None
+            });
+            if let Some(token) = &recovered {
+                self.bump();
+                self.struct_span_err(token.span, "float literals must have an integer part")
+                    .span_suggestion(
+                        token.span,
+                        "must have an integer part",
+                        pprust::token_to_string(token),
+                        Applicability::MachineApplicable,
+                    )
+                    .emit();
+            }
+        }
+
+        let token = recovered.as_ref().unwrap_or(&self.token);
+        match Lit::from_token(token) {
+            Ok(lit) => {
+                self.bump();
+                Ok(lit)
+            }
+            Err(LitError::NotLiteral) => {
+                let msg = format!("unexpected token: {}", self.this_token_descr());
+                Err(self.span_fatal(token.span, &msg))
+            }
+            Err(err) => {
+                let span = token.span;
+                let lit = match token.kind {
+                    token::Literal(lit) => lit,
+                    _ => unreachable!(),
+                };
+                self.bump();
+                self.error_literal_from_token(err, lit, span);
+                // Pack possible quotes and prefixes from the original literal into
+                // the error literal's symbol so they can be pretty-printed faithfully.
+                let suffixless_lit = token::Lit::new(lit.kind, lit.symbol, None);
+                let symbol = Symbol::intern(&suffixless_lit.to_string());
+                let lit = token::Lit::new(token::Err, symbol, lit.suffix);
+                Lit::from_lit_token(lit, span).map_err(|_| unreachable!())
+            }
+        }
+    }
+
+    fn error_literal_from_token(&self, err: LitError, lit: token::Lit, span: Span) {
+        // Checks if `s` looks like i32 or u1234 etc.
+        fn looks_like_width_suffix(first_chars: &[char], s: &str) -> bool {
+            s.len() > 1
+            && s.starts_with(first_chars)
+            && s[1..].chars().all(|c| c.is_ascii_digit())
+        }
+
+        let token::Lit { kind, suffix, .. } = lit;
+        match err {
+            // `NotLiteral` is not an error by itself, so we don't report
+            // it and give the parser opportunity to try something else.
+            LitError::NotLiteral => {}
+            // `LexerError` *is* an error, but it was already reported
+            // by lexer, so here we don't report it the second time.
+            LitError::LexerError => {}
+            LitError::InvalidSuffix => {
+                self.expect_no_suffix(
+                    span,
+                    &format!("{} {} literal", kind.article(), kind.descr()),
+                    suffix,
+                );
+            }
+            LitError::InvalidIntSuffix => {
+                let suf = suffix.expect("suffix error with no suffix").as_str();
+                if looks_like_width_suffix(&['i', 'u'], &suf) {
+                    // If it looks like a width, try to be helpful.
+                    let msg = format!("invalid width `{}` for integer literal", &suf[1..]);
+                    self.struct_span_err(span, &msg)
+                        .help("valid widths are 8, 16, 32, 64 and 128")
+                        .emit();
+                } else {
+                    let msg = format!("invalid suffix `{}` for integer literal", suf);
+                    self.struct_span_err(span, &msg)
+                        .span_label(span, format!("invalid suffix `{}`", suf))
+                        .help("the suffix must be one of the integral types (`u32`, `isize`, etc)")
+                        .emit();
+                }
+            }
+            LitError::InvalidFloatSuffix => {
+                let suf = suffix.expect("suffix error with no suffix").as_str();
+                if looks_like_width_suffix(&['f'], &suf) {
+                    // If it looks like a width, try to be helpful.
+                    let msg = format!("invalid width `{}` for float literal", &suf[1..]);
+                    self.struct_span_err(span, &msg)
+                        .help("valid widths are 32 and 64")
+                        .emit();
+                } else {
+                    let msg = format!("invalid suffix `{}` for float literal", suf);
+                    self.struct_span_err(span, &msg)
+                        .span_label(span, format!("invalid suffix `{}`", suf))
+                        .help("valid suffixes are `f32` and `f64`")
+                        .emit();
+                }
+            }
+            LitError::NonDecimalFloat(base) => {
+                let descr = match base {
+                    16 => "hexadecimal",
+                    8 => "octal",
+                    2 => "binary",
+                    _ => unreachable!(),
+                };
+                self.struct_span_err(span, &format!("{} float literal is not supported", descr))
+                    .span_label(span, "not supported")
+                    .emit();
+            }
+            LitError::IntTooLarge => {
+                self.struct_span_err(span, "integer literal is too large")
+                    .emit();
+            }
+        }
+    }
+
+    pub(super) fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<Symbol>) {
+        if let Some(suf) = suffix {
+            let mut err = if kind == "a tuple index"
+                && [sym::i32, sym::u32, sym::isize, sym::usize].contains(&suf)
+            {
+                // #59553: warn instead of reject out of hand to allow the fix to percolate
+                // through the ecosystem when people fix their macros
+                let mut err = self.sess.span_diagnostic.struct_span_warn(
+                    sp,
+                    &format!("suffixes on {} are invalid", kind),
+                );
+                err.note(&format!(
+                    "`{}` is *temporarily* accepted on tuple index fields as it was \
+                        incorrectly accepted on stable for a few releases",
+                    suf,
+                ));
+                err.help(
+                    "on proc macros, you'll want to use `syn::Index::from` or \
+                        `proc_macro::Literal::*_unsuffixed` for code that will desugar \
+                        to tuple field access",
+                );
+                err.note(
+                    "for more context, see https://github.com/rust-lang/rust/issues/60210",
+                );
+                err
+            } else {
+                self.struct_span_err(sp, &format!("suffixes on {} are invalid", kind))
+            };
+            err.span_label(sp, format!("invalid suffix `{}`", suf));
+            err.emit();
+        }
+    }
+
+    /// Matches `'-' lit | lit` (cf. `ast_validation::AstValidator::check_expr_within_pat`).
+    pub fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
+        maybe_whole_expr!(self);
+
+        let minus_lo = self.token.span;
+        let minus_present = self.eat(&token::BinOp(token::Minus));
+        let lo = self.token.span;
+        let literal = self.parse_lit()?;
+        let hi = self.prev_span;
+        let expr = self.mk_expr(lo.to(hi), ExprKind::Lit(literal), ThinVec::new());
+
+        if minus_present {
+            let minus_hi = self.prev_span;
+            let unary = self.mk_unary(UnOp::Neg, expr);
+            Ok(self.mk_expr(minus_lo.to(minus_hi), unary, ThinVec::new()))
+        } else {
+            Ok(expr)
+        }
+    }
+
+    /// Parses a block or unsafe block.
+    pub(super) fn parse_block_expr(
+        &mut self,
+        opt_label: Option<Label>,
+        lo: Span,
+        blk_mode: BlockCheckMode,
+        outer_attrs: ThinVec<Attribute>,
+    ) -> PResult<'a, P<Expr>> {
+        if let Some(label) = opt_label {
+            self.sess.gated_spans.gate(sym::label_break_value, label.ident.span);
+        }
+
+        self.expect(&token::OpenDelim(token::Brace))?;
+
+        let mut attrs = outer_attrs;
+        attrs.extend(self.parse_inner_attributes()?);
+
+        let blk = self.parse_block_tail(lo, blk_mode)?;
+        Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs))
+    }
+
+    /// Parses a closure expression (e.g., `move |args| expr`).
+    fn parse_closure_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
+        let lo = self.token.span;
+
+        let movability = if self.eat_keyword(kw::Static) {
+            Movability::Static
+        } else {
+            Movability::Movable
+        };
+
+        let asyncness = if self.token.span.rust_2018() {
+            self.parse_asyncness()
+        } else {
+            IsAsync::NotAsync
+        };
+        if asyncness.is_async() {
+            // Feature-gate `async ||` closures.
+            self.sess.gated_spans.gate(sym::async_closure, self.prev_span);
+        }
+
+        let capture_clause = self.parse_capture_clause();
+        let decl = self.parse_fn_block_decl()?;
+        let decl_hi = self.prev_span;
+        let body = match decl.output {
+            FunctionRetTy::Default(_) => {
+                let restrictions = self.restrictions - Restrictions::STMT_EXPR;
+                self.parse_expr_res(restrictions, None)?
+            },
+            _ => {
+                // If an explicit return type is given, require a block to appear (RFC 968).
+                let body_lo = self.token.span;
+                self.parse_block_expr(None, body_lo, BlockCheckMode::Default, ThinVec::new())?
+            }
+        };
+
+        Ok(self.mk_expr(
+            lo.to(body.span),
+            ExprKind::Closure(capture_clause, asyncness, movability, decl, body, lo.to(decl_hi)),
+            attrs))
+    }
+
+    /// Parses an optional `move` prefix to a closure lke construct.
+    fn parse_capture_clause(&mut self) -> CaptureBy {
+        if self.eat_keyword(kw::Move) {
+            CaptureBy::Value
+        } else {
+            CaptureBy::Ref
+        }
+    }
+
+    /// Parses the `|arg, arg|` header of a closure.
+    fn parse_fn_block_decl(&mut self) -> PResult<'a, P<FnDecl>> {
+        let inputs_captures = {
+            if self.eat(&token::OrOr) {
+                Vec::new()
+            } else {
+                self.expect(&token::BinOp(token::Or))?;
+                let args = self.parse_seq_to_before_tokens(
+                    &[&token::BinOp(token::Or), &token::OrOr],
+                    SeqSep::trailing_allowed(token::Comma),
+                    TokenExpectType::NoExpect,
+                    |p| p.parse_fn_block_param()
+                )?.0;
+                self.expect_or()?;
+                args
+            }
+        };
+        let output = self.parse_ret_ty(true)?;
+
+        Ok(P(FnDecl {
+            inputs: inputs_captures,
+            output,
+        }))
+    }
+
+    /// Parses a parameter in a closure header (e.g., `|arg, arg|`).
+    fn parse_fn_block_param(&mut self) -> PResult<'a, Param> {
+        let lo = self.token.span;
+        let attrs = self.parse_outer_attributes()?;
+        let pat = self.parse_pat(PARAM_EXPECTED)?;
+        let t = if self.eat(&token::Colon) {
+            self.parse_ty()?
+        } else {
+            P(Ty {
+                id: DUMMY_NODE_ID,
+                kind: TyKind::Infer,
+                span: self.prev_span,
+            })
+        };
+        let span = lo.to(self.token.span);
+        Ok(Param {
+            attrs: attrs.into(),
+            ty: t,
+            pat,
+            span,
+            id: DUMMY_NODE_ID,
+            is_placeholder: false,
+        })
+    }
+
+    /// Parses an `if` expression (`if` token already eaten).
+    fn parse_if_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
+        let lo = self.prev_span;
+        let cond = self.parse_cond_expr()?;
+
+        // Verify that the parsed `if` condition makes sense as a condition. If it is a block, then
+        // verify that the last statement is either an implicit return (no `;`) or an explicit
+        // return. This won't catch blocks with an explicit `return`, but that would be caught by
+        // the dead code lint.
+        if self.eat_keyword(kw::Else) || !cond.returns() {
+            let sp = self.sess.source_map().next_point(lo);
+            let mut err = self.diagnostic()
+                .struct_span_err(sp, "missing condition for `if` expression");
+            err.span_label(sp, "expected if condition here");
+            return Err(err)
+        }
+        let not_block = self.token != token::OpenDelim(token::Brace);
+        let thn = self.parse_block().map_err(|mut err| {
+            if not_block {
+                err.span_label(lo, "this `if` statement has a condition, but no block");
+            }
+            err
+        })?;
+        let mut els: Option<P<Expr>> = None;
+        let mut hi = thn.span;
+        if self.eat_keyword(kw::Else) {
+            let elexpr = self.parse_else_expr()?;
+            hi = elexpr.span;
+            els = Some(elexpr);
+        }
+        Ok(self.mk_expr(lo.to(hi), ExprKind::If(cond, thn, els), attrs))
+    }
+
+    /// Parses the condition of a `if` or `while` expression.
+    fn parse_cond_expr(&mut self) -> PResult<'a, P<Expr>> {
+        let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
+
+        if let ExprKind::Let(..) = cond.kind {
+            // Remove the last feature gating of a `let` expression since it's stable.
+            self.sess.gated_spans.ungate_last(sym::let_chains, cond.span);
+        }
+
+        Ok(cond)
+    }
+
+    /// Parses a `let $pat = $expr` pseudo-expression.
+    /// The `let` token has already been eaten.
+    fn parse_let_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
+        let lo = self.prev_span;
+        let pat = self.parse_top_pat(GateOr::No)?;
+        self.expect(&token::Eq)?;
+        let expr = self.with_res(
+            Restrictions::NO_STRUCT_LITERAL,
+            |this| this.parse_assoc_expr_with(1 + prec_let_scrutinee_needs_par(), None.into())
+        )?;
+        let span = lo.to(expr.span);
+        self.sess.gated_spans.gate(sym::let_chains, span);
+        Ok(self.mk_expr(span, ExprKind::Let(pat, expr), attrs))
+    }
+
+    /// Parses an `else { ... }` expression (`else` token already eaten).
+    fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
+        if self.eat_keyword(kw::If) {
+            return self.parse_if_expr(ThinVec::new());
+        } else {
+            let blk = self.parse_block()?;
+            return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, None), ThinVec::new()));
+        }
+    }
+
+    /// Parses a `for ... in` expression (`for` token already eaten).
+    fn parse_for_expr(
+        &mut self,
+        opt_label: Option<Label>,
+        span_lo: Span,
+        mut attrs: ThinVec<Attribute>
+    ) -> PResult<'a, P<Expr>> {
+        // Parse: `for <src_pat> in <src_expr> <src_loop_block>`
+
+        // Record whether we are about to parse `for (`.
+        // This is used below for recovery in case of `for ( $stuff ) $block`
+        // in which case we will suggest `for $stuff $block`.
+        let begin_paren = match self.token.kind {
+            token::OpenDelim(token::Paren) => Some(self.token.span),
+            _ => None,
+        };
+
+        let pat = self.parse_top_pat(GateOr::Yes)?;
+        if !self.eat_keyword(kw::In) {
+            let in_span = self.prev_span.between(self.token.span);
+            self.struct_span_err(in_span, "missing `in` in `for` loop")
+                .span_suggestion_short(
+                    in_span,
+                    "try adding `in` here", " in ".into(),
+                    // has been misleading, at least in the past (closed Issue #48492)
+                    Applicability::MaybeIncorrect
+                )
+                .emit();
+        }
+        let in_span = self.prev_span;
+        self.check_for_for_in_in_typo(in_span);
+        let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
+
+        let pat = self.recover_parens_around_for_head(pat, &expr, begin_paren);
+
+        let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?;
+        attrs.extend(iattrs);
+
+        let hi = self.prev_span;
+        Ok(self.mk_expr(span_lo.to(hi), ExprKind::ForLoop(pat, expr, loop_block, opt_label), attrs))
+    }
+
+    /// Parses a `while` or `while let` expression (`while` token already eaten).
+    fn parse_while_expr(
+        &mut self,
+        opt_label: Option<Label>,
+        span_lo: Span,
+        mut attrs: ThinVec<Attribute>
+    ) -> PResult<'a, P<Expr>> {
+        let cond = self.parse_cond_expr()?;
+        let (iattrs, body) = self.parse_inner_attrs_and_block()?;
+        attrs.extend(iattrs);
+        let span = span_lo.to(body.span);
+        Ok(self.mk_expr(span, ExprKind::While(cond, body, opt_label), attrs))
+    }
+
+    /// Parses `loop { ... }` (`loop` token already eaten).
+    fn parse_loop_expr(
+        &mut self,
+        opt_label: Option<Label>,
+        span_lo: Span,
+        mut attrs: ThinVec<Attribute>
+    ) -> PResult<'a, P<Expr>> {
+        let (iattrs, body) = self.parse_inner_attrs_and_block()?;
+        attrs.extend(iattrs);
+        let span = span_lo.to(body.span);
+        Ok(self.mk_expr(span, ExprKind::Loop(body, opt_label), attrs))
+    }
+
+    fn eat_label(&mut self) -> Option<Label> {
+        if let Some(ident) = self.token.lifetime() {
+            let span = self.token.span;
+            self.bump();
+            Some(Label { ident: Ident::new(ident.name, span) })
+        } else {
+            None
+        }
+    }
+
+    /// Parses a `match ... { ... }` expression (`match` token already eaten).
+    fn parse_match_expr(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
+        let match_span = self.prev_span;
+        let lo = self.prev_span;
+        let discriminant = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
+        if let Err(mut e) = self.expect(&token::OpenDelim(token::Brace)) {
+            if self.token == token::Semi {
+                e.span_suggestion_short(
+                    match_span,
+                    "try removing this `match`",
+                    String::new(),
+                    Applicability::MaybeIncorrect // speculative
+                );
+            }
+            return Err(e)
+        }
+        attrs.extend(self.parse_inner_attributes()?);
+
+        let mut arms: Vec<Arm> = Vec::new();
+        while self.token != token::CloseDelim(token::Brace) {
+            match self.parse_arm() {
+                Ok(arm) => arms.push(arm),
+                Err(mut e) => {
+                    // Recover by skipping to the end of the block.
+                    e.emit();
+                    self.recover_stmt();
+                    let span = lo.to(self.token.span);
+                    if self.token == token::CloseDelim(token::Brace) {
+                        self.bump();
+                    }
+                    return Ok(self.mk_expr(span, ExprKind::Match(discriminant, arms), attrs));
+                }
+            }
+        }
+        let hi = self.token.span;
+        self.bump();
+        return Ok(self.mk_expr(lo.to(hi), ExprKind::Match(discriminant, arms), attrs));
+    }
+
+    pub(super) fn parse_arm(&mut self) -> PResult<'a, Arm> {
+        let attrs = self.parse_outer_attributes()?;
+        let lo = self.token.span;
+        let pat = self.parse_top_pat(GateOr::No)?;
+        let guard = if self.eat_keyword(kw::If) {
+            Some(self.parse_expr()?)
+        } else {
+            None
+        };
+        let arrow_span = self.token.span;
+        self.expect(&token::FatArrow)?;
+        let arm_start_span = self.token.span;
+
+        let expr = self.parse_expr_res(Restrictions::STMT_EXPR, None)
+            .map_err(|mut err| {
+                err.span_label(arrow_span, "while parsing the `match` arm starting here");
+                err
+            })?;
+
+        let require_comma = classify::expr_requires_semi_to_be_stmt(&expr)
+            && self.token != token::CloseDelim(token::Brace);
+
+        let hi = self.token.span;
+
+        if require_comma {
+            let cm = self.sess.source_map();
+            self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Brace)])
+                .map_err(|mut err| {
+                    match (cm.span_to_lines(expr.span), cm.span_to_lines(arm_start_span)) {
+                        (Ok(ref expr_lines), Ok(ref arm_start_lines))
+                        if arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col
+                            && expr_lines.lines.len() == 2
+                            && self.token == token::FatArrow => {
+                            // We check whether there's any trailing code in the parse span,
+                            // if there isn't, we very likely have the following:
+                            //
+                            // X |     &Y => "y"
+                            //   |        --    - missing comma
+                            //   |        |
+                            //   |        arrow_span
+                            // X |     &X => "x"
+                            //   |      - ^^ self.token.span
+                            //   |      |
+                            //   |      parsed until here as `"y" & X`
+                            err.span_suggestion_short(
+                                cm.next_point(arm_start_span),
+                                "missing a comma here to end this `match` arm",
+                                ",".to_owned(),
+                                Applicability::MachineApplicable
+                            );
+                        }
+                        _ => {
+                            err.span_label(arrow_span,
+                                           "while parsing the `match` arm starting here");
+                        }
+                    }
+                    err
+                })?;
+        } else {
+            self.eat(&token::Comma);
+        }
+
+        Ok(ast::Arm {
+            attrs,
+            pat,
+            guard,
+            body: expr,
+            span: lo.to(hi),
+            id: DUMMY_NODE_ID,
+            is_placeholder: false,
+        })
+    }
+
+    /// Parses a `try {...}` expression (`try` token already eaten).
+    fn parse_try_block(
+        &mut self,
+        span_lo: Span,
+        mut attrs: ThinVec<Attribute>
+    ) -> PResult<'a, P<Expr>> {
+        let (iattrs, body) = self.parse_inner_attrs_and_block()?;
+        attrs.extend(iattrs);
+        if self.eat_keyword(kw::Catch) {
+            let mut error = self.struct_span_err(self.prev_span,
+                                                 "keyword `catch` cannot follow a `try` block");
+            error.help("try using `match` on the result of the `try` block instead");
+            error.emit();
+            Err(error)
+        } else {
+            let span = span_lo.to(body.span);
+            self.sess.gated_spans.gate(sym::try_blocks, span);
+            Ok(self.mk_expr(span, ExprKind::TryBlock(body), attrs))
+        }
+    }
+
+    fn is_do_catch_block(&self) -> bool {
+        self.token.is_keyword(kw::Do) &&
+        self.is_keyword_ahead(1, &[kw::Catch]) &&
+        self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) &&
+        !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
+    }
+
+    fn is_try_block(&self) -> bool {
+        self.token.is_keyword(kw::Try) &&
+        self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) &&
+        self.token.span.rust_2018() &&
+        // Prevent `while try {} {}`, `if try {} {} else {}`, etc.
+        !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
+    }
+
+    /// Parses an `async move? {...}` expression.
+    fn parse_async_block(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
+        let span_lo = self.token.span;
+        self.expect_keyword(kw::Async)?;
+        let capture_clause = self.parse_capture_clause();
+        let (iattrs, body) = self.parse_inner_attrs_and_block()?;
+        attrs.extend(iattrs);
+        Ok(self.mk_expr(
+            span_lo.to(body.span),
+            ExprKind::Async(capture_clause, DUMMY_NODE_ID, body), attrs))
+    }
+
+    fn is_async_block(&self) -> bool {
+        self.token.is_keyword(kw::Async) &&
+        (
+            ( // `async move {`
+                self.is_keyword_ahead(1, &[kw::Move]) &&
+                self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))
+            ) || ( // `async {`
+                self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace))
+            )
+        )
+    }
+
+    fn maybe_parse_struct_expr(
+        &mut self,
+        lo: Span,
+        path: &ast::Path,
+        attrs: &ThinVec<Attribute>,
+    ) -> Option<PResult<'a, P<Expr>>> {
+        let struct_allowed = !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
+        let certainly_not_a_block = || self.look_ahead(1, |t| t.is_ident()) && (
+            // `{ ident, ` cannot start a block.
+            self.look_ahead(2, |t| t == &token::Comma) ||
+            self.look_ahead(2, |t| t == &token::Colon) && (
+                // `{ ident: token, ` cannot start a block.
+                self.look_ahead(4, |t| t == &token::Comma) ||
+                // `{ ident: ` cannot start a block unless it's a type ascription `ident: Type`.
+                self.look_ahead(3, |t| !t.can_begin_type())
+            )
+        );
+
+        if struct_allowed || certainly_not_a_block() {
+            // This is a struct literal, but we don't can't accept them here.
+            let expr = self.parse_struct_expr(lo, path.clone(), attrs.clone());
+            if let (Ok(expr), false) = (&expr, struct_allowed) {
+                self.struct_span_err(
+                    expr.span,
+                    "struct literals are not allowed here",
+                )
+                .multipart_suggestion(
+                    "surround the struct literal with parentheses",
+                    vec![
+                        (lo.shrink_to_lo(), "(".to_string()),
+                        (expr.span.shrink_to_hi(), ")".to_string()),
+                    ],
+                    Applicability::MachineApplicable,
+                )
+                .emit();
+            }
+            return Some(expr);
+        }
+        None
+    }
+
+    pub(super) fn parse_struct_expr(
+        &mut self,
+        lo: Span,
+        pth: ast::Path,
+        mut attrs: ThinVec<Attribute>
+    ) -> PResult<'a, P<Expr>> {
+        let struct_sp = lo.to(self.prev_span);
+        self.bump();
+        let mut fields = Vec::new();
+        let mut base = None;
+
+        attrs.extend(self.parse_inner_attributes()?);
+
+        while self.token != token::CloseDelim(token::Brace) {
+            if self.eat(&token::DotDot) {
+                let exp_span = self.prev_span;
+                match self.parse_expr() {
+                    Ok(e) => {
+                        base = Some(e);
+                    }
+                    Err(mut e) => {
+                        e.emit();
+                        self.recover_stmt();
+                    }
+                }
+                if self.token == token::Comma {
+                    self.struct_span_err(
+                        exp_span.to(self.prev_span),
+                        "cannot use a comma after the base struct",
+                    )
+                    .span_suggestion_short(
+                        self.token.span,
+                        "remove this comma",
+                        String::new(),
+                        Applicability::MachineApplicable
+                    )
+                    .note("the base struct must always be the last field")
+                    .emit();
+                    self.recover_stmt();
+                }
+                break;
+            }
+
+            let mut recovery_field = None;
+            if let token::Ident(name, _) = self.token.kind {
+                if !self.token.is_reserved_ident() && self.look_ahead(1, |t| *t == token::Colon) {
+                    // Use in case of error after field-looking code: `S { foo: () with a }`.
+                    recovery_field = Some(ast::Field {
+                        ident: Ident::new(name, self.token.span),
+                        span: self.token.span,
+                        expr: self.mk_expr(self.token.span, ExprKind::Err, ThinVec::new()),
+                        is_shorthand: false,
+                        attrs: ThinVec::new(),
+                        id: DUMMY_NODE_ID,
+                        is_placeholder: false,
+                    });
+                }
+            }
+            let mut parsed_field = None;
+            match self.parse_field() {
+                Ok(f) => parsed_field = Some(f),
+                Err(mut e) => {
+                    e.span_label(struct_sp, "while parsing this struct");
+                    e.emit();
+
+                    // If the next token is a comma, then try to parse
+                    // what comes next as additional fields, rather than
+                    // bailing out until next `}`.
+                    if self.token != token::Comma {
+                        self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore);
+                        if self.token != token::Comma {
+                            break;
+                        }
+                    }
+                }
+            }
+
+            match self.expect_one_of(&[token::Comma],
+                                     &[token::CloseDelim(token::Brace)]) {
+                Ok(_) => if let Some(f) = parsed_field.or(recovery_field) {
+                    // Only include the field if there's no parse error for the field name.
+                    fields.push(f);
+                }
+                Err(mut e) => {
+                    if let Some(f) = recovery_field {
+                        fields.push(f);
+                    }
+                    e.span_label(struct_sp, "while parsing this struct");
+                    e.emit();
+                    self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore);
+                    self.eat(&token::Comma);
+                }
+            }
+        }
+
+        let span = lo.to(self.token.span);
+        self.expect(&token::CloseDelim(token::Brace))?;
+        return Ok(self.mk_expr(span, ExprKind::Struct(pth, fields, base), attrs));
+    }
+
+    /// Parses `ident (COLON expr)?`.
+    fn parse_field(&mut self) -> PResult<'a, Field> {
+        let attrs = self.parse_outer_attributes()?;
+        let lo = self.token.span;
+
+        // Check if a colon exists one ahead. This means we're parsing a fieldname.
+        let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| {
+            t == &token::Colon || t == &token::Eq
+        }) {
+            let fieldname = self.parse_field_name()?;
+
+            // Check for an equals token. This means the source incorrectly attempts to
+            // initialize a field with an eq rather than a colon.
+            if self.token == token::Eq {
+                self.diagnostic()
+                    .struct_span_err(self.token.span, "expected `:`, found `=`")
+                    .span_suggestion(
+                        fieldname.span.shrink_to_hi().to(self.token.span),
+                        "replace equals symbol with a colon",
+                        ":".to_string(),
+                        Applicability::MachineApplicable,
+                    )
+                    .emit();
+            }
+            self.bump(); // `:`
+            (fieldname, self.parse_expr()?, false)
+        } else {
+            let fieldname = self.parse_ident_common(false)?;
+
+            // Mimic `x: x` for the `x` field shorthand.
+            let path = ast::Path::from_ident(fieldname);
+            let expr = self.mk_expr(fieldname.span, ExprKind::Path(None, path), ThinVec::new());
+            (fieldname, expr, true)
+        };
+        Ok(ast::Field {
+            ident: fieldname,
+            span: lo.to(expr.span),
+            expr,
+            is_shorthand,
+            attrs: attrs.into(),
+            id: DUMMY_NODE_ID,
+            is_placeholder: false,
+        })
+    }
+
+    fn err_dotdotdot_syntax(&self, span: Span) {
+        self.struct_span_err(span, "unexpected token: `...`")
+            .span_suggestion(
+                span,
+                "use `..` for an exclusive range", "..".to_owned(),
+                Applicability::MaybeIncorrect
+            )
+            .span_suggestion(
+                span,
+                "or `..=` for an inclusive range", "..=".to_owned(),
+                Applicability::MaybeIncorrect
+            )
+            .emit();
+    }
+
+    fn err_larrow_operator(&self, span: Span) {
+        self.struct_span_err(
+            span,
+            "unexpected token: `<-`"
+        ).span_suggestion(
+            span,
+            "if you meant to write a comparison against a negative value, add a \
+             space in between `<` and `-`",
+            "< -".to_string(),
+            Applicability::MaybeIncorrect
+        ).emit();
+    }
+
+    fn mk_assign_op(&self, binop: BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ExprKind {
+        ExprKind::AssignOp(binop, lhs, rhs)
+    }
+
+    fn mk_range(
+        &self,
+        start: Option<P<Expr>>,
+        end: Option<P<Expr>>,
+        limits: RangeLimits
+    ) -> PResult<'a, ExprKind> {
+        if end.is_none() && limits == RangeLimits::Closed {
+            Err(self.span_fatal_err(self.token.span, Error::InclusiveRangeWithNoEnd))
+        } else {
+            Ok(ExprKind::Range(start, end, limits))
+        }
+    }
+
+    fn mk_unary(&self, unop: UnOp, expr: P<Expr>) -> ExprKind {
+        ExprKind::Unary(unop, expr)
+    }
+
+    fn mk_binary(&self, binop: BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ExprKind {
+        ExprKind::Binary(binop, lhs, rhs)
+    }
+
+    fn mk_index(&self, expr: P<Expr>, idx: P<Expr>) -> ExprKind {
+        ExprKind::Index(expr, idx)
+    }
+
+    fn mk_call(&self, f: P<Expr>, args: Vec<P<Expr>>) -> ExprKind {
+        ExprKind::Call(f, args)
+    }
+
+    fn mk_await_expr(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
+        let span = lo.to(self.prev_span);
+        let await_expr = self.mk_expr(span, ExprKind::Await(self_arg), ThinVec::new());
+        self.recover_from_await_method_call();
+        Ok(await_expr)
+    }
+
+    crate fn mk_expr(&self, span: Span, kind: ExprKind, attrs: ThinVec<Attribute>) -> P<Expr> {
+        P(Expr { kind, span, attrs, id: DUMMY_NODE_ID })
+    }
+
+    pub(super) fn mk_expr_err(&self, span: Span) -> P<Expr> {
+        self.mk_expr(span, ExprKind::Err, ThinVec::new())
+    }
+}
diff --git a/src/librustc_parse/parser/generics.rs b/src/librustc_parse/parser/generics.rs
new file mode 100644
index 00000000000..ba5eafc0ed7
--- /dev/null
+++ b/src/librustc_parse/parser/generics.rs
@@ -0,0 +1,308 @@
+use super::Parser;
+
+use syntax::ast::{self, WhereClause, GenericParam, GenericParamKind, GenericBounds, Attribute};
+use syntax::token;
+use syntax::source_map::DUMMY_SP;
+use syntax_pos::symbol::{kw, sym};
+
+use errors::PResult;
+
+impl<'a> Parser<'a> {
+    /// Parses bounds of a lifetime parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
+    ///
+    /// ```
+    /// BOUND = LT_BOUND (e.g., `'a`)
+    /// ```
+    fn parse_lt_param_bounds(&mut self) -> GenericBounds {
+        let mut lifetimes = Vec::new();
+        while self.check_lifetime() {
+            lifetimes.push(ast::GenericBound::Outlives(self.expect_lifetime()));
+
+            if !self.eat_plus() {
+                break
+            }
+        }
+        lifetimes
+    }
+
+    /// Matches `typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?`.
+    fn parse_ty_param(&mut self,
+                      preceding_attrs: Vec<Attribute>)
+                      -> PResult<'a, GenericParam> {
+        let ident = self.parse_ident()?;
+
+        // Parse optional colon and param bounds.
+        let bounds = if self.eat(&token::Colon) {
+            self.parse_generic_bounds(Some(self.prev_span))?
+        } else {
+            Vec::new()
+        };
+
+        let default = if self.eat(&token::Eq) {
+            Some(self.parse_ty()?)
+        } else {
+            None
+        };
+
+        Ok(GenericParam {
+            ident,
+            id: ast::DUMMY_NODE_ID,
+            attrs: preceding_attrs.into(),
+            bounds,
+            kind: GenericParamKind::Type {
+                default,
+            },
+            is_placeholder: false
+        })
+    }
+
+    fn parse_const_param(&mut self, preceding_attrs: Vec<Attribute>) -> PResult<'a, GenericParam> {
+        let lo = self.token.span;
+
+        self.expect_keyword(kw::Const)?;
+        let ident = self.parse_ident()?;
+        self.expect(&token::Colon)?;
+        let ty = self.parse_ty()?;
+
+        self.sess.gated_spans.gate(sym::const_generics, lo.to(self.prev_span));
+
+        Ok(GenericParam {
+            ident,
+            id: ast::DUMMY_NODE_ID,
+            attrs: preceding_attrs.into(),
+            bounds: Vec::new(),
+            kind: GenericParamKind::Const {
+                ty,
+            },
+            is_placeholder: false
+        })
+    }
+
+    /// Parses a (possibly empty) list of lifetime and type parameters, possibly including
+    /// a trailing comma and erroneous trailing attributes.
+    pub(super) fn parse_generic_params(&mut self) -> PResult<'a, Vec<ast::GenericParam>> {
+        let mut params = Vec::new();
+        loop {
+            let attrs = self.parse_outer_attributes()?;
+            if self.check_lifetime() {
+                let lifetime = self.expect_lifetime();
+                // Parse lifetime parameter.
+                let bounds = if self.eat(&token::Colon) {
+                    self.parse_lt_param_bounds()
+                } else {
+                    Vec::new()
+                };
+                params.push(ast::GenericParam {
+                    ident: lifetime.ident,
+                    id: lifetime.id,
+                    attrs: attrs.into(),
+                    bounds,
+                    kind: ast::GenericParamKind::Lifetime,
+                    is_placeholder: false
+                });
+            } else if self.check_keyword(kw::Const) {
+                // Parse const parameter.
+                params.push(self.parse_const_param(attrs)?);
+            } else if self.check_ident() {
+                // Parse type parameter.
+                params.push(self.parse_ty_param(attrs)?);
+            } else if self.token.can_begin_type() {
+                // Trying to write an associated type bound? (#26271)
+                let snapshot = self.clone();
+                match self.parse_ty_where_predicate() {
+                    Ok(where_predicate) => {
+                        self.struct_span_err(
+                            where_predicate.span(),
+                            "bounds on associated types do not belong here",
+                        )
+                        .span_label(where_predicate.span(), "belongs in `where` clause")
+                        .emit();
+                    }
+                    Err(mut err) => {
+                        err.cancel();
+                        std::mem::replace(self, snapshot);
+                        break
+                    }
+                }
+            } else {
+                // Check for trailing attributes and stop parsing.
+                if !attrs.is_empty() {
+                    if !params.is_empty() {
+                        self.struct_span_err(
+                            attrs[0].span,
+                            "trailing attribute after generic parameter",
+                        )
+                        .span_label(attrs[0].span, "attributes must go before parameters")
+                        .emit();
+                    } else {
+                        self.struct_span_err(
+                            attrs[0].span,
+                            &format!("attribute without generic parameters"),
+                        )
+                        .span_label(
+                            attrs[0].span,
+                            "attributes are only permitted when preceding parameters",
+                        )
+                        .emit();
+                    }
+                }
+                break
+            }
+
+            if !self.eat(&token::Comma) {
+                break
+            }
+        }
+        Ok(params)
+    }
+
+    /// Parses a set of optional generic type parameter declarations. Where
+    /// clauses are not parsed here, and must be added later via
+    /// `parse_where_clause()`.
+    ///
+    /// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
+    ///                  | ( < lifetimes , typaramseq ( , )? > )
+    /// where   typaramseq = ( typaram ) | ( typaram , typaramseq )
+    pub(super) fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
+        let span_lo = self.token.span;
+        let (params, span) = if self.eat_lt() {
+            let params = self.parse_generic_params()?;
+            self.expect_gt()?;
+            (params, span_lo.to(self.prev_span))
+        } else {
+            (vec![], self.prev_span.between(self.token.span))
+        };
+        Ok(ast::Generics {
+            params,
+            where_clause: WhereClause {
+                predicates: Vec::new(),
+                span: DUMMY_SP,
+            },
+            span,
+        })
+    }
+
+    /// Parses an optional where-clause and places it in `generics`.
+    ///
+    /// ```ignore (only-for-syntax-highlight)
+    /// where T : Trait<U, V> + 'b, 'a : 'b
+    /// ```
+    pub(super) fn parse_where_clause(&mut self) -> PResult<'a, WhereClause> {
+        let mut where_clause = WhereClause {
+            predicates: Vec::new(),
+            span: self.prev_span.to(self.prev_span),
+        };
+
+        if !self.eat_keyword(kw::Where) {
+            return Ok(where_clause);
+        }
+        let lo = self.prev_span;
+
+        // We are considering adding generics to the `where` keyword as an alternative higher-rank
+        // parameter syntax (as in `where<'a>` or `where<T>`. To avoid that being a breaking
+        // change we parse those generics now, but report an error.
+        if self.choose_generics_over_qpath() {
+            let generics = self.parse_generics()?;
+            self.struct_span_err(
+                generics.span,
+                "generic parameters on `where` clauses are reserved for future use",
+            )
+                .span_label(generics.span, "currently unsupported")
+                .emit();
+        }
+
+        loop {
+            let lo = self.token.span;
+            if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
+                let lifetime = self.expect_lifetime();
+                // Bounds starting with a colon are mandatory, but possibly empty.
+                self.expect(&token::Colon)?;
+                let bounds = self.parse_lt_param_bounds();
+                where_clause.predicates.push(ast::WherePredicate::RegionPredicate(
+                    ast::WhereRegionPredicate {
+                        span: lo.to(self.prev_span),
+                        lifetime,
+                        bounds,
+                    }
+                ));
+            } else if self.check_type() {
+                where_clause.predicates.push(self.parse_ty_where_predicate()?);
+            } else {
+                break
+            }
+
+            if !self.eat(&token::Comma) {
+                break
+            }
+        }
+
+        where_clause.span = lo.to(self.prev_span);
+        Ok(where_clause)
+    }
+
+    fn parse_ty_where_predicate(&mut self) -> PResult<'a, ast::WherePredicate> {
+        let lo = self.token.span;
+        // Parse optional `for<'a, 'b>`.
+        // This `for` is parsed greedily and applies to the whole predicate,
+        // the bounded type can have its own `for` applying only to it.
+        // Examples:
+        // * `for<'a> Trait1<'a>: Trait2<'a /* ok */>`
+        // * `(for<'a> Trait1<'a>): Trait2<'a /* not ok */>`
+        // * `for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /* ok */, 'b /* not ok */>`
+        let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
+
+        // Parse type with mandatory colon and (possibly empty) bounds,
+        // or with mandatory equality sign and the second type.
+        let ty = self.parse_ty()?;
+        if self.eat(&token::Colon) {
+            let bounds = self.parse_generic_bounds(Some(self.prev_span))?;
+            Ok(ast::WherePredicate::BoundPredicate(
+                ast::WhereBoundPredicate {
+                    span: lo.to(self.prev_span),
+                    bound_generic_params: lifetime_defs,
+                    bounded_ty: ty,
+                    bounds,
+                }
+            ))
+        // FIXME: Decide what should be used here, `=` or `==`.
+        // FIXME: We are just dropping the binders in lifetime_defs on the floor here.
+        } else if self.eat(&token::Eq) || self.eat(&token::EqEq) {
+            let rhs_ty = self.parse_ty()?;
+            Ok(ast::WherePredicate::EqPredicate(
+                ast::WhereEqPredicate {
+                    span: lo.to(self.prev_span),
+                    lhs_ty: ty,
+                    rhs_ty,
+                    id: ast::DUMMY_NODE_ID,
+                }
+            ))
+        } else {
+            self.unexpected()
+        }
+    }
+
+    pub(super) fn choose_generics_over_qpath(&self) -> bool {
+        // There's an ambiguity between generic parameters and qualified paths in impls.
+        // If we see `<` it may start both, so we have to inspect some following tokens.
+        // The following combinations can only start generics,
+        // but not qualified paths (with one exception):
+        //     `<` `>` - empty generic parameters
+        //     `<` `#` - generic parameters with attributes
+        //     `<` (LIFETIME|IDENT) `>` - single generic parameter
+        //     `<` (LIFETIME|IDENT) `,` - first generic parameter in a list
+        //     `<` (LIFETIME|IDENT) `:` - generic parameter with bounds
+        //     `<` (LIFETIME|IDENT) `=` - generic parameter with a default
+        //     `<` const                - generic const parameter
+        // The only truly ambiguous case is
+        //     `<` IDENT `>` `::` IDENT ...
+        // we disambiguate it in favor of generics (`impl<T> ::absolute::Path<T> { ... }`)
+        // because this is what almost always expected in practice, qualified paths in impls
+        // (`impl <Type>::AssocTy { ... }`) aren't even allowed by type checker at the moment.
+        self.token == token::Lt &&
+            (self.look_ahead(1, |t| t == &token::Pound || t == &token::Gt) ||
+             self.look_ahead(1, |t| t.is_lifetime() || t.is_ident()) &&
+                self.look_ahead(2, |t| t == &token::Gt || t == &token::Comma ||
+                                       t == &token::Colon || t == &token::Eq) ||
+            self.is_keyword_ahead(1, &[kw::Const]))
+    }
+}
diff --git a/src/librustc_parse/parser/item.rs b/src/librustc_parse/parser/item.rs
new file mode 100644
index 00000000000..3e21436d313
--- /dev/null
+++ b/src/librustc_parse/parser/item.rs
@@ -0,0 +1,2238 @@
+use super::{Parser, PathStyle};
+use super::diagnostics::{Error, dummy_arg, ConsumeClosingDelim};
+
+use crate::maybe_whole;
+
+use syntax::ast::{self, Abi, DUMMY_NODE_ID, Ident, Attribute, AttrKind, AttrStyle, AnonConst, Item};
+use syntax::ast::{ItemKind, ImplItem, ImplItemKind, TraitItem, TraitItemKind, UseTree, UseTreeKind};
+use syntax::ast::{PathSegment, IsAuto, Constness, IsAsync, Unsafety, Defaultness};
+use syntax::ast::{Visibility, VisibilityKind, Mutability, FnHeader, ForeignItem, ForeignItemKind};
+use syntax::ast::{Ty, TyKind, Generics, GenericBounds, TraitRef, EnumDef, VariantData, StructField};
+use syntax::ast::{Mac, MacDelimiter, Block, BindingMode, FnDecl, FnSig, SelfKind, Param};
+use syntax::ptr::P;
+use syntax::ThinVec;
+use syntax::token;
+use syntax::tokenstream::{TokenTree, TokenStream};
+use syntax::source_map::{self, respan, Span};
+use syntax_pos::BytePos;
+use syntax_pos::symbol::{kw, sym};
+
+use log::debug;
+use std::mem;
+use errors::{PResult, Applicability, DiagnosticBuilder, DiagnosticId, StashKey};
+
+/// Whether the type alias or associated type is a concrete type or an opaque type.
+#[derive(Debug)]
+pub(super) enum AliasKind {
+    /// Just a new name for the same type.
+    Weak(P<Ty>),
+    /// Only trait impls of the type will be usable, not the actual type itself.
+    OpaqueTy(GenericBounds),
+}
+
+pub(super) type ItemInfo = (Ident, ItemKind, Option<Vec<Attribute>>);
+
+impl<'a> Parser<'a> {
+    pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> {
+        let attrs = self.parse_outer_attributes()?;
+        self.parse_item_(attrs, true, false)
+    }
+
+    pub(super) fn parse_item_(
+        &mut self,
+        attrs: Vec<Attribute>,
+        macros_allowed: bool,
+        attributes_allowed: bool,
+    ) -> PResult<'a, Option<P<Item>>> {
+        let mut unclosed_delims = vec![];
+        let (ret, tokens) = self.collect_tokens(|this| {
+            let item = this.parse_item_implementation(attrs, macros_allowed, attributes_allowed);
+            unclosed_delims.append(&mut this.unclosed_delims);
+            item
+        })?;
+        self.unclosed_delims.append(&mut unclosed_delims);
+
+        // Once we've parsed an item and recorded the tokens we got while
+        // parsing we may want to store `tokens` into the item we're about to
+        // return. Note, though, that we specifically didn't capture tokens
+        // related to outer attributes. The `tokens` field here may later be
+        // used with procedural macros to convert this item back into a token
+        // stream, but during expansion we may be removing attributes as we go
+        // along.
+        //
+        // If we've got inner attributes then the `tokens` we've got above holds
+        // these inner attributes. If an inner attribute is expanded we won't
+        // actually remove it from the token stream, so we'll just keep yielding
+        // it (bad!). To work around this case for now we just avoid recording
+        // `tokens` if we detect any inner attributes. This should help keep
+        // expansion correct, but we should fix this bug one day!
+        Ok(ret.map(|item| {
+            item.map(|mut i| {
+                if !i.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
+                    i.tokens = Some(tokens);
+                }
+                i
+            })
+        }))
+    }
+
+    /// Parses one of the items allowed by the flags.
+    fn parse_item_implementation(
+        &mut self,
+        attrs: Vec<Attribute>,
+        macros_allowed: bool,
+        attributes_allowed: bool,
+    ) -> PResult<'a, Option<P<Item>>> {
+        maybe_whole!(self, NtItem, |item| {
+            let mut item = item.into_inner();
+            let mut attrs = attrs;
+            mem::swap(&mut item.attrs, &mut attrs);
+            item.attrs.extend(attrs);
+            Some(P(item))
+        });
+
+        let lo = self.token.span;
+
+        let vis = self.parse_visibility(false)?;
+
+        if self.eat_keyword(kw::Use) {
+            // USE ITEM
+            let item_ = ItemKind::Use(P(self.parse_use_tree()?));
+            self.expect_semi()?;
+
+            let span = lo.to(self.prev_span);
+            let item = self.mk_item(span, Ident::invalid(), item_, vis, attrs);
+            return Ok(Some(item));
+        }
+
+        if self.eat_keyword(kw::Extern) {
+            let extern_sp = self.prev_span;
+            if self.eat_keyword(kw::Crate) {
+                return Ok(Some(self.parse_item_extern_crate(lo, vis, attrs)?));
+            }
+
+            let abi = self.parse_opt_abi()?;
+
+            if self.eat_keyword(kw::Fn) {
+                // EXTERN FUNCTION ITEM
+                let fn_span = self.prev_span;
+                let header = FnHeader {
+                    unsafety: Unsafety::Normal,
+                    asyncness: respan(fn_span, IsAsync::NotAsync),
+                    constness: respan(fn_span, Constness::NotConst),
+                    abi,
+                };
+                return self.parse_item_fn(lo, vis, attrs, header);
+            } else if self.check(&token::OpenDelim(token::Brace)) {
+                return Ok(Some(
+                    self.parse_item_foreign_mod(lo, abi, vis, attrs, extern_sp)?,
+                ));
+            }
+
+            self.unexpected()?;
+        }
+
+        if self.is_static_global() {
+            self.bump();
+            // STATIC ITEM
+            let m = self.parse_mutability();
+            let info = self.parse_item_const(Some(m))?;
+            return self.mk_item_with_info(attrs, lo, vis, info);
+        }
+
+        if self.eat_keyword(kw::Const) {
+            let const_span = self.prev_span;
+            if [kw::Fn, kw::Unsafe, kw::Extern].iter().any(|k| self.check_keyword(*k)) {
+                // CONST FUNCTION ITEM
+                let unsafety = self.parse_unsafety();
+
+                if self.check_keyword(kw::Extern) {
+                    self.sess.gated_spans.gate(sym::const_extern_fn, lo.to(self.token.span));
+                }
+                let abi = self.parse_extern_abi()?;
+                self.bump(); // `fn`
+
+                let header = FnHeader {
+                    unsafety,
+                    asyncness: respan(const_span, IsAsync::NotAsync),
+                    constness: respan(const_span, Constness::Const),
+                    abi,
+                };
+                return self.parse_item_fn(lo, vis, attrs, header);
+            }
+
+            // CONST ITEM
+            if self.eat_keyword(kw::Mut) {
+                let prev_span = self.prev_span;
+                self.struct_span_err(prev_span, "const globals cannot be mutable")
+                    .span_label(prev_span, "cannot be mutable")
+                    .span_suggestion(
+                        const_span,
+                        "you might want to declare a static instead",
+                        "static".to_owned(),
+                        Applicability::MaybeIncorrect,
+                    )
+                    .emit();
+            }
+
+            let info = self.parse_item_const(None)?;
+            return self.mk_item_with_info(attrs, lo, vis, info);
+        }
+
+        // Parses `async unsafe? fn`.
+        if self.check_keyword(kw::Async) {
+            let async_span = self.token.span;
+            if self.is_keyword_ahead(1, &[kw::Fn])
+                || self.is_keyword_ahead(2, &[kw::Fn])
+            {
+                // ASYNC FUNCTION ITEM
+                self.bump(); // `async`
+                let unsafety = self.parse_unsafety(); // `unsafe`?
+                self.expect_keyword(kw::Fn)?; // `fn`
+                let fn_span = self.prev_span;
+                let asyncness = respan(async_span, IsAsync::Async {
+                    closure_id: DUMMY_NODE_ID,
+                    return_impl_trait_id: DUMMY_NODE_ID,
+                });
+                self.ban_async_in_2015(async_span);
+                let header = FnHeader {
+                    unsafety,
+                    asyncness,
+                    constness: respan(fn_span, Constness::NotConst),
+                    abi: Abi::new(sym::Rust, fn_span),
+                };
+                return self.parse_item_fn(lo, vis, attrs, header);
+            }
+        }
+
+        if self.check_keyword(kw::Unsafe) &&
+            self.is_keyword_ahead(1, &[kw::Trait, kw::Auto])
+        {
+            // UNSAFE TRAIT ITEM
+            self.bump(); // `unsafe`
+            let info = self.parse_item_trait(lo, Unsafety::Unsafe)?;
+            return self.mk_item_with_info(attrs, lo, vis, info);
+        }
+
+        if self.check_keyword(kw::Impl) ||
+           self.check_keyword(kw::Unsafe) &&
+                self.is_keyword_ahead(1, &[kw::Impl]) ||
+           self.check_keyword(kw::Default) &&
+                self.is_keyword_ahead(1, &[kw::Impl, kw::Unsafe])
+        {
+            // IMPL ITEM
+            let defaultness = self.parse_defaultness();
+            let unsafety = self.parse_unsafety();
+            self.expect_keyword(kw::Impl)?;
+            let info = self.parse_item_impl(unsafety, defaultness)?;
+            return self.mk_item_with_info(attrs, lo, vis, info);
+        }
+
+        if self.check_keyword(kw::Fn) {
+            // FUNCTION ITEM
+            self.bump();
+            let fn_span = self.prev_span;
+            let header = FnHeader {
+                unsafety: Unsafety::Normal,
+                asyncness: respan(fn_span, IsAsync::NotAsync),
+                constness: respan(fn_span, Constness::NotConst),
+                abi: Abi::new(sym::Rust, fn_span),
+            };
+            return self.parse_item_fn(lo, vis, attrs, header);
+        }
+
+        if self.check_keyword(kw::Unsafe)
+            && self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace))
+        {
+            // UNSAFE FUNCTION ITEM
+            self.bump(); // `unsafe`
+            // `{` is also expected after `unsafe`; in case of error, include it in the diagnostic.
+            self.check(&token::OpenDelim(token::Brace));
+            let abi = self.parse_extern_abi()?;
+            self.expect_keyword(kw::Fn)?;
+            let fn_span = self.prev_span;
+            let header = FnHeader {
+                unsafety: Unsafety::Unsafe,
+                asyncness: respan(fn_span, IsAsync::NotAsync),
+                constness: respan(fn_span, Constness::NotConst),
+                abi,
+            };
+            return self.parse_item_fn(lo, vis, attrs, header);
+        }
+
+        if self.eat_keyword(kw::Mod) {
+            // MODULE ITEM
+            let info = self.parse_item_mod(&attrs[..])?;
+            return self.mk_item_with_info(attrs, lo, vis, info);
+        }
+
+        if let Some(type_) = self.eat_type() {
+            let (ident, alias, generics) = type_?;
+            // TYPE ITEM
+            let item_ = match alias {
+                AliasKind::Weak(ty) => ItemKind::TyAlias(ty, generics),
+                AliasKind::OpaqueTy(bounds) => ItemKind::OpaqueTy(bounds, generics),
+            };
+            let span = lo.to(self.prev_span);
+            return Ok(Some(self.mk_item(span, ident, item_, vis, attrs)));
+        }
+
+        if self.eat_keyword(kw::Enum) {
+            // ENUM ITEM
+            let info = self.parse_item_enum()?;
+            return self.mk_item_with_info(attrs, lo, vis, info);
+        }
+
+        if self.check_keyword(kw::Trait)
+            || (self.check_keyword(kw::Auto)
+                && self.is_keyword_ahead(1, &[kw::Trait]))
+        {
+            // TRAIT ITEM
+            let info = self.parse_item_trait(lo, Unsafety::Normal)?;
+            return self.mk_item_with_info(attrs, lo, vis, info);
+        }
+
+        if self.eat_keyword(kw::Struct) {
+            // STRUCT ITEM
+            let info = self.parse_item_struct()?;
+            return self.mk_item_with_info(attrs, lo, vis, info);
+        }
+
+        if self.is_union_item() {
+            // UNION ITEM
+            self.bump();
+            let info = self.parse_item_union()?;
+            return self.mk_item_with_info(attrs, lo, vis, info);
+        }
+
+        if let Some(macro_def) = self.eat_macro_def(&attrs, &vis, lo)? {
+            return Ok(Some(macro_def));
+        }
+
+        // Verify whether we have encountered a struct or method definition where the user forgot to
+        // add the `struct` or `fn` keyword after writing `pub`: `pub S {}`
+        if vis.node.is_pub() &&
+            self.check_ident() &&
+            self.look_ahead(1, |t| *t != token::Not)
+        {
+            // Space between `pub` keyword and the identifier
+            //
+            //     pub   S {}
+            //        ^^^ `sp` points here
+            let sp = self.prev_span.between(self.token.span);
+            let full_sp = self.prev_span.to(self.token.span);
+            let ident_sp = self.token.span;
+            if self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) {
+                // possible public struct definition where `struct` was forgotten
+                let ident = self.parse_ident().unwrap();
+                let msg = format!("add `struct` here to parse `{}` as a public struct",
+                                  ident);
+                let mut err = self.diagnostic()
+                    .struct_span_err(sp, "missing `struct` for struct definition");
+                err.span_suggestion_short(
+                    sp, &msg, " struct ".into(), Applicability::MaybeIncorrect // speculative
+                );
+                return Err(err);
+            } else if self.look_ahead(1, |t| *t == token::OpenDelim(token::Paren)) {
+                let ident = self.parse_ident().unwrap();
+                self.bump();  // `(`
+                let kw_name = self.recover_first_param();
+                self.consume_block(token::Paren, ConsumeClosingDelim::Yes);
+                let (kw, kw_name, ambiguous) = if self.check(&token::RArrow) {
+                    self.eat_to_tokens(&[&token::OpenDelim(token::Brace)]);
+                    self.bump();  // `{`
+                    ("fn", kw_name, false)
+                } else if self.check(&token::OpenDelim(token::Brace)) {
+                    self.bump();  // `{`
+                    ("fn", kw_name, false)
+                } else if self.check(&token::Colon) {
+                    let kw = "struct";
+                    (kw, kw, false)
+                } else {
+                    ("fn` or `struct", "function or struct", true)
+                };
+
+                let msg = format!("missing `{}` for {} definition", kw, kw_name);
+                let mut err = self.diagnostic().struct_span_err(sp, &msg);
+                if !ambiguous {
+                    self.consume_block(token::Brace, ConsumeClosingDelim::Yes);
+                    let suggestion = format!("add `{}` here to parse `{}` as a public {}",
+                                             kw,
+                                             ident,
+                                             kw_name);
+                    err.span_suggestion_short(
+                        sp, &suggestion, format!(" {} ", kw), Applicability::MachineApplicable
+                    );
+                } else {
+                    if let Ok(snippet) = self.span_to_snippet(ident_sp) {
+                        err.span_suggestion(
+                            full_sp,
+                            "if you meant to call a macro, try",
+                            format!("{}!", snippet),
+                            // this is the `ambiguous` conditional branch
+                            Applicability::MaybeIncorrect
+                        );
+                    } else {
+                        err.help("if you meant to call a macro, remove the `pub` \
+                                  and add a trailing `!` after the identifier");
+                    }
+                }
+                return Err(err);
+            } else if self.look_ahead(1, |t| *t == token::Lt) {
+                let ident = self.parse_ident().unwrap();
+                self.eat_to_tokens(&[&token::Gt]);
+                self.bump();  // `>`
+                let (kw, kw_name, ambiguous) = if self.eat(&token::OpenDelim(token::Paren)) {
+                    ("fn", self.recover_first_param(), false)
+                } else if self.check(&token::OpenDelim(token::Brace)) {
+                    ("struct", "struct", false)
+                } else {
+                    ("fn` or `struct", "function or struct", true)
+                };
+                let msg = format!("missing `{}` for {} definition", kw, kw_name);
+                let mut err = self.diagnostic().struct_span_err(sp, &msg);
+                if !ambiguous {
+                    err.span_suggestion_short(
+                        sp,
+                        &format!("add `{}` here to parse `{}` as a public {}", kw, ident, kw_name),
+                        format!(" {} ", kw),
+                        Applicability::MachineApplicable,
+                    );
+                }
+                return Err(err);
+            }
+        }
+        self.parse_macro_use_or_failure(attrs, macros_allowed, attributes_allowed, lo, vis)
+    }
+
+    pub(super) fn mk_item_with_info(
+        &self,
+        attrs: Vec<Attribute>,
+        lo: Span,
+        vis: Visibility,
+        info: ItemInfo,
+    ) -> PResult<'a, Option<P<Item>>> {
+        let (ident, item, extra_attrs) = info;
+        let span = lo.to(self.prev_span);
+        let attrs = Self::maybe_append(attrs, extra_attrs);
+        Ok(Some(self.mk_item(span, ident, item, vis, attrs)))
+    }
+
+    fn maybe_append<T>(mut lhs: Vec<T>, mut rhs: Option<Vec<T>>) -> Vec<T> {
+        if let Some(ref mut rhs) = rhs {
+            lhs.append(rhs);
+        }
+        lhs
+    }
+
+    /// This is the fall-through for parsing items.
+    fn parse_macro_use_or_failure(
+        &mut self,
+        attrs: Vec<Attribute> ,
+        macros_allowed: bool,
+        attributes_allowed: bool,
+        lo: Span,
+        visibility: Visibility
+    ) -> PResult<'a, Option<P<Item>>> {
+        if macros_allowed && self.token.is_path_start() &&
+                !(self.is_async_fn() && self.token.span.rust_2015()) {
+            // MACRO INVOCATION ITEM
+
+            let prev_span = self.prev_span;
+            self.complain_if_pub_macro(&visibility.node, prev_span);
+
+            let mac_lo = self.token.span;
+
+            // Item macro
+            let path = self.parse_path(PathStyle::Mod)?;
+            self.expect(&token::Not)?;
+            let (delim, tts) = self.expect_delimited_token_tree()?;
+            if delim != MacDelimiter::Brace && !self.eat(&token::Semi) {
+                self.report_invalid_macro_expansion_item();
+            }
+
+            let hi = self.prev_span;
+            let mac = Mac {
+                path,
+                tts,
+                delim,
+                span: mac_lo.to(hi),
+                prior_type_ascription: self.last_type_ascription,
+            };
+            let item =
+                self.mk_item(lo.to(hi), Ident::invalid(), ItemKind::Mac(mac), visibility, attrs);
+            return Ok(Some(item));
+        }
+
+        // FAILURE TO PARSE ITEM
+        match visibility.node {
+            VisibilityKind::Inherited => {}
+            _ => {
+                return Err(self.span_fatal(self.prev_span, "unmatched visibility `pub`"));
+            }
+        }
+
+        if !attributes_allowed && !attrs.is_empty() {
+            self.expected_item_err(&attrs)?;
+        }
+        Ok(None)
+    }
+
+    /// Emits an expected-item-after-attributes error.
+    fn expected_item_err(&mut self, attrs: &[Attribute]) -> PResult<'a,  ()> {
+        let message = match attrs.last() {
+            Some(&Attribute { kind: AttrKind::DocComment(_), .. }) =>
+                "expected item after doc comment",
+            _ =>
+                "expected item after attributes",
+        };
+
+        let mut err = self.diagnostic().struct_span_err(self.prev_span, message);
+        if attrs.last().unwrap().is_doc_comment() {
+            err.span_label(self.prev_span, "this doc comment doesn't document anything");
+        }
+        Err(err)
+    }
+
+    pub(super) fn is_async_fn(&self) -> bool {
+        self.token.is_keyword(kw::Async) &&
+            self.is_keyword_ahead(1, &[kw::Fn])
+    }
+
+    /// Parses a macro invocation inside a `trait`, `impl` or `extern` block.
+    fn parse_assoc_macro_invoc(&mut self, item_kind: &str, vis: Option<&Visibility>,
+                               at_end: &mut bool) -> PResult<'a, Option<Mac>>
+    {
+        if self.token.is_path_start() &&
+                !(self.is_async_fn() && self.token.span.rust_2015()) {
+            let prev_span = self.prev_span;
+            let lo = self.token.span;
+            let path = self.parse_path(PathStyle::Mod)?;
+
+            if path.segments.len() == 1 {
+                if !self.eat(&token::Not) {
+                    return Err(self.missing_assoc_item_kind_err(item_kind, prev_span));
+                }
+            } else {
+                self.expect(&token::Not)?;
+            }
+
+            if let Some(vis) = vis {
+                self.complain_if_pub_macro(&vis.node, prev_span);
+            }
+
+            *at_end = true;
+
+            // eat a matched-delimiter token tree:
+            let (delim, tts) = self.expect_delimited_token_tree()?;
+            if delim != MacDelimiter::Brace {
+                self.expect_semi()?;
+            }
+
+            Ok(Some(Mac {
+                path,
+                tts,
+                delim,
+                span: lo.to(self.prev_span),
+                prior_type_ascription: self.last_type_ascription,
+            }))
+        } else {
+            Ok(None)
+        }
+    }
+
+    fn missing_assoc_item_kind_err(&self, item_type: &str, prev_span: Span)
+                                   -> DiagnosticBuilder<'a>
+    {
+        let expected_kinds = if item_type == "extern" {
+            "missing `fn`, `type`, or `static`"
+        } else {
+            "missing `fn`, `type`, or `const`"
+        };
+
+        // Given this code `path(`, it seems like this is not
+        // setting the visibility of a macro invocation, but rather
+        // a mistyped method declaration.
+        // Create a diagnostic pointing out that `fn` is missing.
+        //
+        // x |     pub path(&self) {
+        //   |        ^ missing `fn`, `type`, or `const`
+        //     pub  path(
+        //        ^^ `sp` below will point to this
+        let sp = prev_span.between(self.prev_span);
+        let mut err = self.diagnostic().struct_span_err(
+            sp,
+            &format!("{} for {}-item declaration",
+                     expected_kinds, item_type));
+        err.span_label(sp, expected_kinds);
+        err
+    }
+
+    /// Parses an implementation item, `impl` keyword is already parsed.
+    ///
+    ///    impl<'a, T> TYPE { /* impl items */ }
+    ///    impl<'a, T> TRAIT for TYPE { /* impl items */ }
+    ///    impl<'a, T> !TRAIT for TYPE { /* impl items */ }
+    ///
+    /// We actually parse slightly more relaxed grammar for better error reporting and recovery.
+    ///     `impl` GENERICS `!`? TYPE `for`? (TYPE | `..`) (`where` PREDICATES)? `{` BODY `}`
+    ///     `impl` GENERICS `!`? TYPE (`where` PREDICATES)? `{` BODY `}`
+    fn parse_item_impl(&mut self, unsafety: Unsafety, defaultness: Defaultness)
+                       -> PResult<'a, ItemInfo> {
+        // First, parse generic parameters if necessary.
+        let mut generics = if self.choose_generics_over_qpath() {
+            self.parse_generics()?
+        } else {
+            Generics::default()
+        };
+
+        // Disambiguate `impl !Trait for Type { ... }` and `impl ! { ... }` for the never type.
+        let polarity = if self.check(&token::Not) && self.look_ahead(1, |t| t.can_begin_type()) {
+            self.bump(); // `!`
+            ast::ImplPolarity::Negative
+        } else {
+            ast::ImplPolarity::Positive
+        };
+
+        // Parse both types and traits as a type, then reinterpret if necessary.
+        let err_path = |span| ast::Path::from_ident(Ident::new(kw::Invalid, span));
+        let ty_first = if self.token.is_keyword(kw::For) &&
+                          self.look_ahead(1, |t| t != &token::Lt) {
+            let span = self.prev_span.between(self.token.span);
+            self.struct_span_err(span, "missing trait in a trait impl").emit();
+            P(Ty { kind: TyKind::Path(None, err_path(span)), span, id: DUMMY_NODE_ID })
+        } else {
+            self.parse_ty()?
+        };
+
+        // If `for` is missing we try to recover.
+        let has_for = self.eat_keyword(kw::For);
+        let missing_for_span = self.prev_span.between(self.token.span);
+
+        let ty_second = if self.token == token::DotDot {
+            // We need to report this error after `cfg` expansion for compatibility reasons
+            self.bump(); // `..`, do not add it to expected tokens
+            Some(self.mk_ty(self.prev_span, TyKind::Err))
+        } else if has_for || self.token.can_begin_type() {
+            Some(self.parse_ty()?)
+        } else {
+            None
+        };
+
+        generics.where_clause = self.parse_where_clause()?;
+
+        let (impl_items, attrs) = self.parse_impl_body()?;
+
+        let item_kind = match ty_second {
+            Some(ty_second) => {
+                // impl Trait for Type
+                if !has_for {
+                    self.struct_span_err(missing_for_span, "missing `for` in a trait impl")
+                        .span_suggestion_short(
+                            missing_for_span,
+                            "add `for` here",
+                            " for ".to_string(),
+                            Applicability::MachineApplicable,
+                        ).emit();
+                }
+
+                let ty_first = ty_first.into_inner();
+                let path = match ty_first.kind {
+                    // This notably includes paths passed through `ty` macro fragments (#46438).
+                    TyKind::Path(None, path) => path,
+                    _ => {
+                        self.span_err(ty_first.span, "expected a trait, found type");
+                        err_path(ty_first.span)
+                    }
+                };
+                let trait_ref = TraitRef { path, ref_id: ty_first.id };
+
+                ItemKind::Impl(unsafety, polarity, defaultness,
+                               generics, Some(trait_ref), ty_second, impl_items)
+            }
+            None => {
+                // impl Type
+                ItemKind::Impl(unsafety, polarity, defaultness,
+                               generics, None, ty_first, impl_items)
+            }
+        };
+
+        Ok((Ident::invalid(), item_kind, Some(attrs)))
+    }
+
+    fn parse_impl_body(&mut self) -> PResult<'a, (Vec<ImplItem>, Vec<Attribute>)> {
+        self.expect(&token::OpenDelim(token::Brace))?;
+        let attrs = self.parse_inner_attributes()?;
+
+        let mut impl_items = Vec::new();
+        while !self.eat(&token::CloseDelim(token::Brace)) {
+            let mut at_end = false;
+            match self.parse_impl_item(&mut at_end) {
+                Ok(impl_item) => impl_items.push(impl_item),
+                Err(mut err) => {
+                    err.emit();
+                    if !at_end {
+                        self.consume_block(token::Brace, ConsumeClosingDelim::Yes);
+                        break;
+                    }
+                }
+            }
+        }
+        Ok((impl_items, attrs))
+    }
+
+    /// Parses an impl item.
+    pub fn parse_impl_item(&mut self, at_end: &mut bool) -> PResult<'a, ImplItem> {
+        maybe_whole!(self, NtImplItem, |x| x);
+        let attrs = self.parse_outer_attributes()?;
+        let mut unclosed_delims = vec![];
+        let (mut item, tokens) = self.collect_tokens(|this| {
+            let item = this.parse_impl_item_(at_end, attrs);
+            unclosed_delims.append(&mut this.unclosed_delims);
+            item
+        })?;
+        self.unclosed_delims.append(&mut unclosed_delims);
+
+        // See `parse_item` for why this clause is here.
+        if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
+            item.tokens = Some(tokens);
+        }
+        Ok(item)
+    }
+
+    fn parse_impl_item_(
+        &mut self,
+        at_end: &mut bool,
+        mut attrs: Vec<Attribute>,
+    ) -> PResult<'a, ImplItem> {
+        let lo = self.token.span;
+        let vis = self.parse_visibility(false)?;
+        let defaultness = self.parse_defaultness();
+        let (name, kind, generics) = if let Some(type_) = self.eat_type() {
+            let (name, alias, generics) = type_?;
+            let kind = match alias {
+                AliasKind::Weak(typ) => ast::ImplItemKind::TyAlias(typ),
+                AliasKind::OpaqueTy(bounds) => ast::ImplItemKind::OpaqueTy(bounds),
+            };
+            (name, kind, generics)
+        } else if self.is_const_item() {
+            self.parse_impl_const()?
+        } else if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(&vis), at_end)? {
+            // FIXME: code copied from `parse_macro_use_or_failure` -- use abstraction!
+            (Ident::invalid(), ast::ImplItemKind::Macro(mac), Generics::default())
+        } else {
+            let (name, inner_attrs, generics, kind) = self.parse_impl_method(at_end)?;
+            attrs.extend(inner_attrs);
+            (name, kind, generics)
+        };
+
+        Ok(ImplItem {
+            id: DUMMY_NODE_ID,
+            span: lo.to(self.prev_span),
+            ident: name,
+            vis,
+            defaultness,
+            attrs,
+            generics,
+            kind,
+            tokens: None,
+        })
+    }
+
+    /// Parses defaultness (i.e., `default` or nothing).
+    fn parse_defaultness(&mut self) -> Defaultness {
+        // `pub` is included for better error messages
+        if self.check_keyword(kw::Default) &&
+            self.is_keyword_ahead(1, &[
+                kw::Impl,
+                kw::Const,
+                kw::Async,
+                kw::Fn,
+                kw::Unsafe,
+                kw::Extern,
+                kw::Type,
+                kw::Pub,
+            ])
+        {
+            self.bump(); // `default`
+            Defaultness::Default
+        } else {
+            Defaultness::Final
+        }
+    }
+
+    /// Returns `true` if we are looking at `const ID`
+    /// (returns `false` for things like `const fn`, etc.).
+    fn is_const_item(&self) -> bool {
+        self.token.is_keyword(kw::Const) &&
+            !self.is_keyword_ahead(1, &[kw::Fn, kw::Unsafe])
+    }
+
+    /// This parses the grammar:
+    ///     ImplItemConst = "const" Ident ":" Ty "=" Expr ";"
+    fn parse_impl_const(&mut self) -> PResult<'a, (Ident, ImplItemKind, Generics)> {
+        self.expect_keyword(kw::Const)?;
+        let name = self.parse_ident()?;
+        self.expect(&token::Colon)?;
+        let typ = self.parse_ty()?;
+        self.expect(&token::Eq)?;
+        let expr = self.parse_expr()?;
+        self.expect_semi()?;
+        Ok((name, ImplItemKind::Const(typ, expr), Generics::default()))
+    }
+
+    /// Parses `auto? trait Foo { ... }` or `trait Foo = Bar;`.
+    fn parse_item_trait(&mut self, lo: Span, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
+        // Parse optional `auto` prefix.
+        let is_auto = if self.eat_keyword(kw::Auto) {
+            IsAuto::Yes
+        } else {
+            IsAuto::No
+        };
+
+        self.expect_keyword(kw::Trait)?;
+        let ident = self.parse_ident()?;
+        let mut tps = self.parse_generics()?;
+
+        // Parse optional colon and supertrait bounds.
+        let had_colon = self.eat(&token::Colon);
+        let span_at_colon = self.prev_span;
+        let bounds = if had_colon {
+            self.parse_generic_bounds(Some(self.prev_span))?
+        } else {
+            Vec::new()
+        };
+
+        let span_before_eq = self.prev_span;
+        if self.eat(&token::Eq) {
+            // It's a trait alias.
+            if had_colon {
+                let span = span_at_colon.to(span_before_eq);
+                self.struct_span_err(span, "bounds are not allowed on trait aliases")
+                    .emit();
+            }
+
+            let bounds = self.parse_generic_bounds(None)?;
+            tps.where_clause = self.parse_where_clause()?;
+            self.expect_semi()?;
+
+            let whole_span = lo.to(self.prev_span);
+            if is_auto == IsAuto::Yes {
+                let msg = "trait aliases cannot be `auto`";
+                self.struct_span_err(whole_span, msg)
+                    .span_label(whole_span, msg)
+                    .emit();
+            }
+            if unsafety != Unsafety::Normal {
+                let msg = "trait aliases cannot be `unsafe`";
+                self.struct_span_err(whole_span, msg)
+                    .span_label(whole_span, msg)
+                    .emit();
+            }
+
+            self.sess.gated_spans.gate(sym::trait_alias, whole_span);
+
+            Ok((ident, ItemKind::TraitAlias(tps, bounds), None))
+        } else {
+            // It's a normal trait.
+            tps.where_clause = self.parse_where_clause()?;
+            self.expect(&token::OpenDelim(token::Brace))?;
+            let mut trait_items = vec![];
+            while !self.eat(&token::CloseDelim(token::Brace)) {
+                if let token::DocComment(_) = self.token.kind {
+                    if self.look_ahead(1,
+                    |tok| tok == &token::CloseDelim(token::Brace)) {
+                        self.diagnostic().struct_span_err_with_code(
+                            self.token.span,
+                            "found a documentation comment that doesn't document anything",
+                            DiagnosticId::Error("E0584".into()),
+                        )
+                        .help(
+                            "doc comments must come before what they document, maybe a \
+                            comment was intended with `//`?",
+                        )
+                        .emit();
+                        self.bump();
+                        continue;
+                    }
+                }
+                let mut at_end = false;
+                match self.parse_trait_item(&mut at_end) {
+                    Ok(item) => trait_items.push(item),
+                    Err(mut e) => {
+                        e.emit();
+                        if !at_end {
+                            self.consume_block(token::Brace, ConsumeClosingDelim::Yes);
+                            break;
+                        }
+                    }
+                }
+            }
+            Ok((ident, ItemKind::Trait(is_auto, unsafety, tps, bounds, trait_items), None))
+        }
+    }
+
+    /// Parses the items in a trait declaration.
+    pub fn parse_trait_item(&mut self, at_end: &mut bool) -> PResult<'a, TraitItem> {
+        maybe_whole!(self, NtTraitItem, |x| x);
+        let attrs = self.parse_outer_attributes()?;
+        let mut unclosed_delims = vec![];
+        let (mut item, tokens) = self.collect_tokens(|this| {
+            let item = this.parse_trait_item_(at_end, attrs);
+            unclosed_delims.append(&mut this.unclosed_delims);
+            item
+        })?;
+        self.unclosed_delims.append(&mut unclosed_delims);
+        // See `parse_item` for why this clause is here.
+        if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
+            item.tokens = Some(tokens);
+        }
+        Ok(item)
+    }
+
+    fn parse_trait_item_(
+        &mut self,
+        at_end: &mut bool,
+        mut attrs: Vec<Attribute>,
+    ) -> PResult<'a, TraitItem> {
+        let lo = self.token.span;
+        self.eat_bad_pub();
+        let (name, kind, generics) = if self.eat_keyword(kw::Type) {
+            self.parse_trait_item_assoc_ty()?
+        } else if self.is_const_item() {
+            self.parse_trait_item_const()?
+        } else if let Some(mac) = self.parse_assoc_macro_invoc("trait", None, &mut false)? {
+            // trait item macro.
+            (Ident::invalid(), TraitItemKind::Macro(mac), Generics::default())
+        } else {
+            self.parse_trait_item_method(at_end, &mut attrs)?
+        };
+
+        Ok(TraitItem {
+            id: DUMMY_NODE_ID,
+            ident: name,
+            attrs,
+            generics,
+            kind,
+            span: lo.to(self.prev_span),
+            tokens: None,
+        })
+    }
+
+    fn parse_trait_item_const(&mut self) -> PResult<'a, (Ident, TraitItemKind, Generics)> {
+        self.expect_keyword(kw::Const)?;
+        let ident = self.parse_ident()?;
+        self.expect(&token::Colon)?;
+        let ty = self.parse_ty()?;
+        let default = if self.eat(&token::Eq) {
+            Some(self.parse_expr()?)
+        } else {
+            None
+        };
+        self.expect_semi()?;
+        Ok((ident, TraitItemKind::Const(ty, default), Generics::default()))
+    }
+
+    /// Parses the following grammar:
+    ///
+    ///     TraitItemAssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty]
+    fn parse_trait_item_assoc_ty(&mut self) -> PResult<'a, (Ident, TraitItemKind, Generics)> {
+        let ident = self.parse_ident()?;
+        let mut generics = self.parse_generics()?;
+
+        // Parse optional colon and param bounds.
+        let bounds = if self.eat(&token::Colon) {
+            self.parse_generic_bounds(None)?
+        } else {
+            Vec::new()
+        };
+        generics.where_clause = self.parse_where_clause()?;
+
+        let default = if self.eat(&token::Eq) {
+            Some(self.parse_ty()?)
+        } else {
+            None
+        };
+        self.expect_semi()?;
+
+        Ok((ident, TraitItemKind::Type(bounds, default), generics))
+    }
+
+    /// Parses a `UseTree`.
+    ///
+    /// ```
+    /// USE_TREE = [`::`] `*` |
+    ///            [`::`] `{` USE_TREE_LIST `}` |
+    ///            PATH `::` `*` |
+    ///            PATH `::` `{` USE_TREE_LIST `}` |
+    ///            PATH [`as` IDENT]
+    /// ```
+    fn parse_use_tree(&mut self) -> PResult<'a, UseTree> {
+        let lo = self.token.span;
+
+        let mut prefix = ast::Path { segments: Vec::new(), span: lo.shrink_to_lo() };
+        let kind = if self.check(&token::OpenDelim(token::Brace)) ||
+                      self.check(&token::BinOp(token::Star)) ||
+                      self.is_import_coupler() {
+            // `use *;` or `use ::*;` or `use {...};` or `use ::{...};`
+            let mod_sep_ctxt = self.token.span.ctxt();
+            if self.eat(&token::ModSep) {
+                prefix.segments.push(
+                    PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt))
+                );
+            }
+
+            self.parse_use_tree_glob_or_nested()?
+        } else {
+            // `use path::*;` or `use path::{...};` or `use path;` or `use path as bar;`
+            prefix = self.parse_path(PathStyle::Mod)?;
+
+            if self.eat(&token::ModSep) {
+                self.parse_use_tree_glob_or_nested()?
+            } else {
+                UseTreeKind::Simple(self.parse_rename()?, DUMMY_NODE_ID, DUMMY_NODE_ID)
+            }
+        };
+
+        Ok(UseTree { prefix, kind, span: lo.to(self.prev_span) })
+    }
+
+    /// Parses `*` or `{...}`.
+    fn parse_use_tree_glob_or_nested(&mut self) -> PResult<'a, UseTreeKind> {
+        Ok(if self.eat(&token::BinOp(token::Star)) {
+            UseTreeKind::Glob
+        } else {
+            UseTreeKind::Nested(self.parse_use_tree_list()?)
+        })
+    }
+
+    /// Parses a `UseTreeKind::Nested(list)`.
+    ///
+    /// ```
+    /// USE_TREE_LIST = Ø | (USE_TREE `,`)* USE_TREE [`,`]
+    /// ```
+    fn parse_use_tree_list(&mut self) -> PResult<'a, Vec<(UseTree, ast::NodeId)>> {
+        self.parse_delim_comma_seq(token::Brace, |p| Ok((p.parse_use_tree()?, DUMMY_NODE_ID)))
+            .map(|(r, _)| r)
+    }
+
+    fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
+        if self.eat_keyword(kw::As) {
+            self.parse_ident_or_underscore().map(Some)
+        } else {
+            Ok(None)
+        }
+    }
+
+    fn parse_ident_or_underscore(&mut self) -> PResult<'a, ast::Ident> {
+        match self.token.kind {
+            token::Ident(name, false) if name == kw::Underscore => {
+                let span = self.token.span;
+                self.bump();
+                Ok(Ident::new(name, span))
+            }
+            _ => self.parse_ident(),
+        }
+    }
+
+    /// Parses `extern crate` links.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// extern crate foo;
+    /// extern crate bar as foo;
+    /// ```
+    fn parse_item_extern_crate(
+        &mut self,
+        lo: Span,
+        visibility: Visibility,
+        attrs: Vec<Attribute>
+    ) -> PResult<'a, P<Item>> {
+        // Accept `extern crate name-like-this` for better diagnostics
+        let orig_name = self.parse_crate_name_with_dashes()?;
+        let (item_name, orig_name) = if let Some(rename) = self.parse_rename()? {
+            (rename, Some(orig_name.name))
+        } else {
+            (orig_name, None)
+        };
+        self.expect_semi()?;
+
+        let span = lo.to(self.prev_span);
+        Ok(self.mk_item(span, item_name, ItemKind::ExternCrate(orig_name), visibility, attrs))
+    }
+
+    fn parse_crate_name_with_dashes(&mut self) -> PResult<'a, ast::Ident> {
+        let error_msg = "crate name using dashes are not valid in `extern crate` statements";
+        let suggestion_msg = "if the original crate name uses dashes you need to use underscores \
+                              in the code";
+        let mut ident = if self.token.is_keyword(kw::SelfLower) {
+            self.parse_path_segment_ident()
+        } else {
+            self.parse_ident()
+        }?;
+        let mut idents = vec![];
+        let mut replacement = vec![];
+        let mut fixed_crate_name = false;
+        // Accept `extern crate name-like-this` for better diagnostics.
+        let dash = token::BinOp(token::BinOpToken::Minus);
+        if self.token == dash {  // Do not include `-` as part of the expected tokens list.
+            while self.eat(&dash) {
+                fixed_crate_name = true;
+                replacement.push((self.prev_span, "_".to_string()));
+                idents.push(self.parse_ident()?);
+            }
+        }
+        if fixed_crate_name {
+            let fixed_name_sp = ident.span.to(idents.last().unwrap().span);
+            let mut fixed_name = format!("{}", ident.name);
+            for part in idents {
+                fixed_name.push_str(&format!("_{}", part.name));
+            }
+            ident = Ident::from_str_and_span(&fixed_name, fixed_name_sp);
+
+            self.struct_span_err(fixed_name_sp, error_msg)
+                .span_label(fixed_name_sp, "dash-separated idents are not valid")
+                .multipart_suggestion(suggestion_msg, replacement, Applicability::MachineApplicable)
+                .emit();
+        }
+        Ok(ident)
+    }
+
+    /// Parses `extern` for foreign ABIs modules.
+    ///
+    /// `extern` is expected to have been
+    /// consumed before calling this method.
+    ///
+    /// # Examples
+    ///
+    /// ```ignore (only-for-syntax-highlight)
+    /// extern "C" {}
+    /// extern {}
+    /// ```
+    fn parse_item_foreign_mod(
+        &mut self,
+        lo: Span,
+        abi: Abi,
+        visibility: Visibility,
+        mut attrs: Vec<Attribute>,
+        extern_sp: Span,
+    ) -> PResult<'a, P<Item>> {
+        self.expect(&token::OpenDelim(token::Brace))?;
+
+        attrs.extend(self.parse_inner_attributes()?);
+
+        let mut foreign_items = vec![];
+        while !self.eat(&token::CloseDelim(token::Brace)) {
+            foreign_items.push(self.parse_foreign_item(extern_sp)?);
+        }
+
+        let prev_span = self.prev_span;
+        let m = ast::ForeignMod {
+            abi,
+            items: foreign_items
+        };
+        let invalid = Ident::invalid();
+        Ok(self.mk_item(lo.to(prev_span), invalid, ItemKind::ForeignMod(m), visibility, attrs))
+    }
+
+    /// Parses a foreign item.
+    pub fn parse_foreign_item(&mut self, extern_sp: Span) -> PResult<'a, ForeignItem> {
+        maybe_whole!(self, NtForeignItem, |ni| ni);
+
+        let attrs = self.parse_outer_attributes()?;
+        let lo = self.token.span;
+        let visibility = self.parse_visibility(false)?;
+
+        // FOREIGN STATIC ITEM
+        // Treat `const` as `static` for error recovery, but don't add it to expected tokens.
+        if self.check_keyword(kw::Static) || self.token.is_keyword(kw::Const) {
+            if self.token.is_keyword(kw::Const) {
+                let mut err = self
+                    .struct_span_err(self.token.span, "extern items cannot be `const`");
+
+
+                // The user wrote 'const fn'
+                if self.is_keyword_ahead(1, &[kw::Fn, kw::Unsafe]) {
+                    err.emit();
+                    // Consume `const`
+                    self.bump();
+                    // Consume `unsafe` if present, since `extern` blocks
+                    // don't allow it. This will leave behind a plain 'fn'
+                    self.eat_keyword(kw::Unsafe);
+                    // Treat 'const fn` as a plain `fn` for error recovery purposes.
+                    // We've already emitted an error, so compilation is guaranteed
+                    // to fail
+                    return Ok(self.parse_item_foreign_fn(visibility, lo, attrs, extern_sp)?);
+                }
+                err.span_suggestion(
+                        self.token.span,
+                        "try using a static value",
+                        "static".to_owned(),
+                        Applicability::MachineApplicable
+                );
+                err.emit();
+            }
+            self.bump(); // `static` or `const`
+            return Ok(self.parse_item_foreign_static(visibility, lo, attrs)?);
+        }
+        // FOREIGN FUNCTION ITEM
+        if self.check_keyword(kw::Fn) {
+            return Ok(self.parse_item_foreign_fn(visibility, lo, attrs, extern_sp)?);
+        }
+        // FOREIGN TYPE ITEM
+        if self.check_keyword(kw::Type) {
+            return Ok(self.parse_item_foreign_type(visibility, lo, attrs)?);
+        }
+
+        match self.parse_assoc_macro_invoc("extern", Some(&visibility), &mut false)? {
+            Some(mac) => {
+                Ok(
+                    ForeignItem {
+                        ident: Ident::invalid(),
+                        span: lo.to(self.prev_span),
+                        id: DUMMY_NODE_ID,
+                        attrs,
+                        vis: visibility,
+                        kind: ForeignItemKind::Macro(mac),
+                    }
+                )
+            }
+            None => {
+                if !attrs.is_empty()  {
+                    self.expected_item_err(&attrs)?;
+                }
+
+                self.unexpected()
+            }
+        }
+    }
+
+    /// Parses a static item from a foreign module.
+    /// Assumes that the `static` keyword is already parsed.
+    fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
+                                 -> PResult<'a, ForeignItem> {
+        let mutbl = self.parse_mutability();
+        let ident = self.parse_ident()?;
+        self.expect(&token::Colon)?;
+        let ty = self.parse_ty()?;
+        let hi = self.token.span;
+        self.expect_semi()?;
+        Ok(ForeignItem {
+            ident,
+            attrs,
+            kind: ForeignItemKind::Static(ty, mutbl),
+            id: DUMMY_NODE_ID,
+            span: lo.to(hi),
+            vis,
+        })
+    }
+
+    /// Parses a type from a foreign module.
+    fn parse_item_foreign_type(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
+                             -> PResult<'a, ForeignItem> {
+        self.expect_keyword(kw::Type)?;
+
+        let ident = self.parse_ident()?;
+        let hi = self.token.span;
+        self.expect_semi()?;
+        Ok(ast::ForeignItem {
+            ident,
+            attrs,
+            kind: ForeignItemKind::Ty,
+            id: DUMMY_NODE_ID,
+            span: lo.to(hi),
+            vis
+        })
+    }
+
+    fn is_static_global(&mut self) -> bool {
+        if self.check_keyword(kw::Static) {
+            // Check if this could be a closure.
+            !self.look_ahead(1, |token| {
+                if token.is_keyword(kw::Move) {
+                    return true;
+                }
+                match token.kind {
+                    token::BinOp(token::Or) | token::OrOr => true,
+                    _ => false,
+                }
+            })
+        } else {
+            false
+        }
+    }
+
+    /// Parse `["const" | ("static" "mut"?)] $ident ":" $ty = $expr` with
+    /// `["const" | ("static" "mut"?)]` already parsed and stored in `m`.
+    ///
+    /// When `m` is `"const"`, `$ident` may also be `"_"`.
+    fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<'a, ItemInfo> {
+        let id = if m.is_none() { self.parse_ident_or_underscore() } else { self.parse_ident() }?;
+
+        // Parse the type of a `const` or `static mut?` item.
+        // That is, the `":" $ty` fragment.
+        let ty = if self.token == token::Eq {
+            self.recover_missing_const_type(id, m)
+        } else {
+            // Not `=` so expect `":"" $ty` as usual.
+            self.expect(&token::Colon)?;
+            self.parse_ty()?
+        };
+
+        self.expect(&token::Eq)?;
+        let e = self.parse_expr()?;
+        self.expect_semi()?;
+        let item = match m {
+            Some(m) => ItemKind::Static(ty, m, e),
+            None => ItemKind::Const(ty, e),
+        };
+        Ok((id, item, None))
+    }
+
+    /// We were supposed to parse `:` but instead, we're already at `=`.
+    /// This means that the type is missing.
+    fn recover_missing_const_type(&mut self, id: Ident, m: Option<Mutability>) -> P<Ty> {
+        // Construct the error and stash it away with the hope
+        // that typeck will later enrich the error with a type.
+        let kind = match m {
+            Some(Mutability::Mutable) => "static mut",
+            Some(Mutability::Immutable) => "static",
+            None => "const",
+        };
+        let mut err = self.struct_span_err(id.span, &format!("missing type for `{}` item", kind));
+        err.span_suggestion(
+            id.span,
+            "provide a type for the item",
+            format!("{}: <type>", id),
+            Applicability::HasPlaceholders,
+        );
+        err.stash(id.span, StashKey::ItemNoType);
+
+        // The user intended that the type be inferred,
+        // so treat this as if the user wrote e.g. `const A: _ = expr;`.
+        P(Ty {
+            kind: TyKind::Infer,
+            span: id.span,
+            id: ast::DUMMY_NODE_ID,
+        })
+    }
+
+    /// Parses `type Foo = Bar;` or returns `None`
+    /// without modifying the parser state.
+    fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, Generics)>> {
+        // This parses the grammar:
+        //     Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
+        if self.eat_keyword(kw::Type) {
+            Some(self.parse_type_alias())
+        } else {
+            None
+        }
+    }
+
+    /// Parses a type alias or opaque type.
+    fn parse_type_alias(&mut self) -> PResult<'a, (Ident, AliasKind, Generics)> {
+        let ident = self.parse_ident()?;
+        let mut tps = self.parse_generics()?;
+        tps.where_clause = self.parse_where_clause()?;
+        self.expect(&token::Eq)?;
+        let alias = if self.check_keyword(kw::Impl) {
+            self.bump();
+            let bounds = self.parse_generic_bounds(Some(self.prev_span))?;
+            AliasKind::OpaqueTy(bounds)
+        } else {
+            let ty = self.parse_ty()?;
+            AliasKind::Weak(ty)
+        };
+        self.expect_semi()?;
+        Ok((ident, alias, tps))
+    }
+
+    /// Parses an enum declaration.
+    fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
+        let id = self.parse_ident()?;
+        let mut generics = self.parse_generics()?;
+        generics.where_clause = self.parse_where_clause()?;
+        self.expect(&token::OpenDelim(token::Brace))?;
+
+        let enum_definition = self.parse_enum_def(&generics).map_err(|e| {
+            self.recover_stmt();
+            self.eat(&token::CloseDelim(token::Brace));
+            e
+        })?;
+        Ok((id, ItemKind::Enum(enum_definition, generics), None))
+    }
+
+    /// Parses the part of an enum declaration following the `{`.
+    fn parse_enum_def(&mut self, _generics: &Generics) -> PResult<'a, EnumDef> {
+        let mut variants = Vec::new();
+        while self.token != token::CloseDelim(token::Brace) {
+            let variant_attrs = self.parse_outer_attributes()?;
+            let vlo = self.token.span;
+
+            self.eat_bad_pub();
+            let ident = self.parse_ident()?;
+
+            let struct_def = if self.check(&token::OpenDelim(token::Brace)) {
+                // Parse a struct variant.
+                let (fields, recovered) = self.parse_record_struct_body()?;
+                VariantData::Struct(fields, recovered)
+            } else if self.check(&token::OpenDelim(token::Paren)) {
+                VariantData::Tuple(
+                    self.parse_tuple_struct_body()?,
+                    DUMMY_NODE_ID,
+                )
+            } else {
+                VariantData::Unit(DUMMY_NODE_ID)
+            };
+
+            let disr_expr = if self.eat(&token::Eq) {
+                Some(AnonConst {
+                    id: DUMMY_NODE_ID,
+                    value: self.parse_expr()?,
+                })
+            } else {
+                None
+            };
+
+            let vr = ast::Variant {
+                ident,
+                id: DUMMY_NODE_ID,
+                attrs: variant_attrs,
+                data: struct_def,
+                disr_expr,
+                span: vlo.to(self.prev_span),
+                is_placeholder: false,
+            };
+            variants.push(vr);
+
+            if !self.eat(&token::Comma) {
+                if self.token.is_ident() && !self.token.is_reserved_ident() {
+                    let sp = self.sess.source_map().next_point(self.prev_span);
+                    self.struct_span_err(sp, "missing comma")
+                        .span_suggestion_short(
+                            sp,
+                            "missing comma",
+                            ",".to_owned(),
+                            Applicability::MaybeIncorrect,
+                        )
+                        .emit();
+                } else {
+                    break;
+                }
+            }
+        }
+        self.expect(&token::CloseDelim(token::Brace))?;
+
+        Ok(ast::EnumDef { variants })
+    }
+
+    /// Parses `struct Foo { ... }`.
+    fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
+        let class_name = self.parse_ident()?;
+
+        let mut generics = self.parse_generics()?;
+
+        // There is a special case worth noting here, as reported in issue #17904.
+        // If we are parsing a tuple struct it is the case that the where clause
+        // should follow the field list. Like so:
+        //
+        // struct Foo<T>(T) where T: Copy;
+        //
+        // If we are parsing a normal record-style struct it is the case
+        // that the where clause comes before the body, and after the generics.
+        // So if we look ahead and see a brace or a where-clause we begin
+        // parsing a record style struct.
+        //
+        // Otherwise if we look ahead and see a paren we parse a tuple-style
+        // struct.
+
+        let vdata = if self.token.is_keyword(kw::Where) {
+            generics.where_clause = self.parse_where_clause()?;
+            if self.eat(&token::Semi) {
+                // If we see a: `struct Foo<T> where T: Copy;` style decl.
+                VariantData::Unit(DUMMY_NODE_ID)
+            } else {
+                // If we see: `struct Foo<T> where T: Copy { ... }`
+                let (fields, recovered) = self.parse_record_struct_body()?;
+                VariantData::Struct(fields, recovered)
+            }
+        // No `where` so: `struct Foo<T>;`
+        } else if self.eat(&token::Semi) {
+            VariantData::Unit(DUMMY_NODE_ID)
+        // Record-style struct definition
+        } else if self.token == token::OpenDelim(token::Brace) {
+            let (fields, recovered) = self.parse_record_struct_body()?;
+            VariantData::Struct(fields, recovered)
+        // Tuple-style struct definition with optional where-clause.
+        } else if self.token == token::OpenDelim(token::Paren) {
+            let body = VariantData::Tuple(self.parse_tuple_struct_body()?, DUMMY_NODE_ID);
+            generics.where_clause = self.parse_where_clause()?;
+            self.expect_semi()?;
+            body
+        } else {
+            let token_str = self.this_token_descr();
+            let mut err = self.fatal(&format!(
+                "expected `where`, `{{`, `(`, or `;` after struct name, found {}",
+                token_str
+            ));
+            err.span_label(self.token.span, "expected `where`, `{`, `(`, or `;` after struct name");
+            return Err(err);
+        };
+
+        Ok((class_name, ItemKind::Struct(vdata, generics), None))
+    }
+
+    /// Parses `union Foo { ... }`.
+    fn parse_item_union(&mut self) -> PResult<'a, ItemInfo> {
+        let class_name = self.parse_ident()?;
+
+        let mut generics = self.parse_generics()?;
+
+        let vdata = if self.token.is_keyword(kw::Where) {
+            generics.where_clause = self.parse_where_clause()?;
+            let (fields, recovered) = self.parse_record_struct_body()?;
+            VariantData::Struct(fields, recovered)
+        } else if self.token == token::OpenDelim(token::Brace) {
+            let (fields, recovered) = self.parse_record_struct_body()?;
+            VariantData::Struct(fields, recovered)
+        } else {
+            let token_str = self.this_token_descr();
+            let mut err = self.fatal(&format!(
+                "expected `where` or `{{` after union name, found {}", token_str));
+            err.span_label(self.token.span, "expected `where` or `{` after union name");
+            return Err(err);
+        };
+
+        Ok((class_name, ItemKind::Union(vdata, generics), None))
+    }
+
+    pub(super) fn is_union_item(&self) -> bool {
+        self.token.is_keyword(kw::Union) &&
+        self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
+    }
+
+    fn parse_record_struct_body(
+        &mut self,
+    ) -> PResult<'a, (Vec<StructField>, /* recovered */ bool)> {
+        let mut fields = Vec::new();
+        let mut recovered = false;
+        if self.eat(&token::OpenDelim(token::Brace)) {
+            while self.token != token::CloseDelim(token::Brace) {
+                let field = self.parse_struct_decl_field().map_err(|e| {
+                    self.consume_block(token::Brace, ConsumeClosingDelim::No);
+                    recovered = true;
+                    e
+                });
+                match field {
+                    Ok(field) => fields.push(field),
+                    Err(mut err) => {
+                        err.emit();
+                        break;
+                    }
+                }
+            }
+            self.eat(&token::CloseDelim(token::Brace));
+        } else {
+            let token_str = self.this_token_descr();
+            let mut err = self.fatal(&format!(
+                    "expected `where`, or `{{` after struct name, found {}", token_str));
+            err.span_label(self.token.span, "expected `where`, or `{` after struct name");
+            return Err(err);
+        }
+
+        Ok((fields, recovered))
+    }
+
+    fn parse_tuple_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
+        // This is the case where we find `struct Foo<T>(T) where T: Copy;`
+        // Unit like structs are handled in parse_item_struct function
+        self.parse_paren_comma_seq(|p| {
+            let attrs = p.parse_outer_attributes()?;
+            let lo = p.token.span;
+            let vis = p.parse_visibility(true)?;
+            let ty = p.parse_ty()?;
+            Ok(StructField {
+                span: lo.to(ty.span),
+                vis,
+                ident: None,
+                id: DUMMY_NODE_ID,
+                ty,
+                attrs,
+                is_placeholder: false,
+            })
+        }).map(|(r, _)| r)
+    }
+
+    /// Parses an element of a struct declaration.
+    fn parse_struct_decl_field(&mut self) -> PResult<'a, StructField> {
+        let attrs = self.parse_outer_attributes()?;
+        let lo = self.token.span;
+        let vis = self.parse_visibility(false)?;
+        self.parse_single_struct_field(lo, vis, attrs)
+    }
+
+    /// Parses a structure field declaration.
+    fn parse_single_struct_field(&mut self,
+                                     lo: Span,
+                                     vis: Visibility,
+                                     attrs: Vec<Attribute> )
+                                     -> PResult<'a, StructField> {
+        let mut seen_comma: bool = false;
+        let a_var = self.parse_name_and_ty(lo, vis, attrs)?;
+        if self.token == token::Comma {
+            seen_comma = true;
+        }
+        match self.token.kind {
+            token::Comma => {
+                self.bump();
+            }
+            token::CloseDelim(token::Brace) => {}
+            token::DocComment(_) => {
+                let previous_span = self.prev_span;
+                let mut err = self.span_fatal_err(self.token.span, Error::UselessDocComment);
+                self.bump(); // consume the doc comment
+                let comma_after_doc_seen = self.eat(&token::Comma);
+                // `seen_comma` is always false, because we are inside doc block
+                // condition is here to make code more readable
+                if seen_comma == false && comma_after_doc_seen == true {
+                    seen_comma = true;
+                }
+                if comma_after_doc_seen || self.token == token::CloseDelim(token::Brace) {
+                    err.emit();
+                } else {
+                    if seen_comma == false {
+                        let sp = self.sess.source_map().next_point(previous_span);
+                        err.span_suggestion(
+                            sp,
+                            "missing comma here",
+                            ",".into(),
+                            Applicability::MachineApplicable
+                        );
+                    }
+                    return Err(err);
+                }
+            }
+            _ => {
+                let sp = self.sess.source_map().next_point(self.prev_span);
+                let mut err = self.struct_span_err(sp, &format!("expected `,`, or `}}`, found {}",
+                                                                self.this_token_descr()));
+                if self.token.is_ident() {
+                    // This is likely another field; emit the diagnostic and keep going
+                    err.span_suggestion(
+                        sp,
+                        "try adding a comma",
+                        ",".into(),
+                        Applicability::MachineApplicable,
+                    );
+                    err.emit();
+                } else {
+                    return Err(err)
+                }
+            }
+        }
+        Ok(a_var)
+    }
+
+    /// Parses a structure field.
+    fn parse_name_and_ty(
+        &mut self,
+        lo: Span,
+        vis: Visibility,
+        attrs: Vec<Attribute>
+    ) -> PResult<'a, StructField> {
+        let name = self.parse_ident()?;
+        self.expect(&token::Colon)?;
+        let ty = self.parse_ty()?;
+        Ok(StructField {
+            span: lo.to(self.prev_span),
+            ident: Some(name),
+            vis,
+            id: DUMMY_NODE_ID,
+            ty,
+            attrs,
+            is_placeholder: false,
+        })
+    }
+
+    pub(super) fn eat_macro_def(
+        &mut self,
+        attrs: &[Attribute],
+        vis: &Visibility,
+        lo: Span
+    ) -> PResult<'a, Option<P<Item>>> {
+        let token_lo = self.token.span;
+        let (ident, def) = if self.eat_keyword(kw::Macro) {
+            let ident = self.parse_ident()?;
+            let tokens = if self.check(&token::OpenDelim(token::Brace)) {
+                match self.parse_token_tree() {
+                    TokenTree::Delimited(_, _, tts) => tts,
+                    _ => unreachable!(),
+                }
+            } else if self.check(&token::OpenDelim(token::Paren)) {
+                let args = self.parse_token_tree();
+                let body = if self.check(&token::OpenDelim(token::Brace)) {
+                    self.parse_token_tree()
+                } else {
+                    self.unexpected()?;
+                    unreachable!()
+                };
+                TokenStream::new(vec![
+                    args.into(),
+                    TokenTree::token(token::FatArrow, token_lo.to(self.prev_span)).into(),
+                    body.into(),
+                ])
+            } else {
+                self.unexpected()?;
+                unreachable!()
+            };
+
+            (ident, ast::MacroDef { tokens: tokens.into(), legacy: false })
+        } else if self.check_keyword(sym::macro_rules) &&
+                  self.look_ahead(1, |t| *t == token::Not) &&
+                  self.look_ahead(2, |t| t.is_ident()) {
+            let prev_span = self.prev_span;
+            self.complain_if_pub_macro(&vis.node, prev_span);
+            self.bump();
+            self.bump();
+
+            let ident = self.parse_ident()?;
+            let (delim, tokens) = self.expect_delimited_token_tree()?;
+            if delim != MacDelimiter::Brace && !self.eat(&token::Semi) {
+                self.report_invalid_macro_expansion_item();
+            }
+
+            (ident, ast::MacroDef { tokens, legacy: true })
+        } else {
+            return Ok(None);
+        };
+
+        let span = lo.to(self.prev_span);
+
+        if !def.legacy {
+            self.sess.gated_spans.gate(sym::decl_macro, span);
+        }
+
+        Ok(Some(self.mk_item(span, ident, ItemKind::MacroDef(def), vis.clone(), attrs.to_vec())))
+    }
+
+    fn complain_if_pub_macro(&self, vis: &VisibilityKind, sp: Span) {
+        match *vis {
+            VisibilityKind::Inherited => {}
+            _ => {
+                let mut err = if self.token.is_keyword(sym::macro_rules) {
+                    let mut err = self.diagnostic()
+                        .struct_span_err(sp, "can't qualify macro_rules invocation with `pub`");
+                    err.span_suggestion(
+                        sp,
+                        "try exporting the macro",
+                        "#[macro_export]".to_owned(),
+                        Applicability::MaybeIncorrect // speculative
+                    );
+                    err
+                } else {
+                    let mut err = self.diagnostic()
+                        .struct_span_err(sp, "can't qualify macro invocation with `pub`");
+                    err.help("try adjusting the macro to put `pub` inside the invocation");
+                    err
+                };
+                err.emit();
+            }
+        }
+    }
+
+    fn report_invalid_macro_expansion_item(&self) {
+        self.struct_span_err(
+            self.prev_span,
+            "macros that expand to items must be delimited with braces or followed by a semicolon",
+        ).multipart_suggestion(
+            "change the delimiters to curly braces",
+            vec![
+                (self.prev_span.with_hi(self.prev_span.lo() + BytePos(1)), String::from(" {")),
+                (self.prev_span.with_lo(self.prev_span.hi() - BytePos(1)), '}'.to_string()),
+            ],
+            Applicability::MaybeIncorrect,
+        ).span_suggestion(
+            self.sess.source_map().next_point(self.prev_span),
+            "add a semicolon",
+            ';'.to_string(),
+            Applicability::MaybeIncorrect,
+        ).emit();
+    }
+
+    fn mk_item(&self, span: Span, ident: Ident, kind: ItemKind, vis: Visibility,
+               attrs: Vec<Attribute>) -> P<Item> {
+        P(Item {
+            ident,
+            attrs,
+            id: DUMMY_NODE_ID,
+            kind,
+            vis,
+            span,
+            tokens: None,
+        })
+    }
+}
+
+/// The parsing configuration used to parse a parameter list (see `parse_fn_params`).
+pub(super) struct ParamCfg {
+    /// Is `self` is allowed as the first parameter?
+    pub is_self_allowed: bool,
+    /// Is `...` allowed as the tail of the parameter list?
+    pub allow_c_variadic: bool,
+    /// `is_name_required` decides if, per-parameter,
+    /// the parameter must have a pattern or just a type.
+    pub is_name_required: fn(&token::Token) -> bool,
+}
+
+/// Parsing of functions and methods.
+impl<'a> Parser<'a> {
+    /// Parses an item-position function declaration.
+    fn parse_item_fn(
+        &mut self,
+        lo: Span,
+        vis: Visibility,
+        attrs: Vec<Attribute>,
+        header: FnHeader,
+    ) -> PResult<'a, Option<P<Item>>> {
+        let (ident, decl, generics) = self.parse_fn_sig(ParamCfg {
+            is_self_allowed: false,
+            allow_c_variadic: header.abi.symbol == sym::C && header.unsafety == Unsafety::Unsafe,
+            is_name_required: |_| true,
+        })?;
+        let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
+        let kind = ItemKind::Fn(FnSig { decl, header }, generics, body);
+        self.mk_item_with_info(attrs, lo, vis, (ident, kind, Some(inner_attrs)))
+    }
+
+    /// Parses a function declaration from a foreign module.
+    fn parse_item_foreign_fn(
+        &mut self,
+        vis: ast::Visibility,
+        lo: Span,
+        attrs: Vec<Attribute>,
+        extern_sp: Span,
+    ) -> PResult<'a, ForeignItem> {
+        self.expect_keyword(kw::Fn)?;
+        let (ident, decl, generics) = self.parse_fn_sig(ParamCfg {
+            is_self_allowed: false,
+            allow_c_variadic: true,
+            is_name_required: |_| true,
+        })?;
+        let span = lo.to(self.token.span);
+        self.parse_semi_or_incorrect_foreign_fn_body(&ident, extern_sp)?;
+        Ok(ast::ForeignItem {
+            ident,
+            attrs,
+            kind: ForeignItemKind::Fn(decl, generics),
+            id: DUMMY_NODE_ID,
+            span,
+            vis,
+        })
+    }
+
+    /// Parses a method or a macro invocation in a trait impl.
+    fn parse_impl_method(
+        &mut self,
+        at_end: &mut bool,
+    ) -> PResult<'a, (Ident, Vec<Attribute>, Generics, ImplItemKind)> {
+        let (ident, sig, generics) = self.parse_method_sig(|_| true)?;
+        *at_end = true;
+        let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
+        Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(sig, body)))
+    }
+
+    fn parse_trait_item_method(
+        &mut self,
+        at_end: &mut bool,
+        attrs: &mut Vec<Attribute>,
+    ) -> PResult<'a, (Ident, TraitItemKind, Generics)> {
+        // This is somewhat dubious; We don't want to allow
+        // argument names to be left off if there is a definition...
+        //
+        // We don't allow argument names to be left off in edition 2018.
+        let (ident, sig, generics) = self.parse_method_sig(|t| t.span.rust_2018())?;
+        let body = self.parse_trait_method_body(at_end, attrs)?;
+        Ok((ident, TraitItemKind::Method(sig, body), generics))
+    }
+
+    /// Parse the "body" of a method in a trait item definition.
+    /// This can either be `;` when there's no body,
+    /// or e.g. a block when the method is a provided one.
+    fn parse_trait_method_body(
+        &mut self,
+        at_end: &mut bool,
+        attrs: &mut Vec<Attribute>,
+    ) -> PResult<'a, Option<P<Block>>> {
+        Ok(match self.token.kind {
+            token::Semi => {
+                debug!("parse_trait_method_body(): parsing required method");
+                self.bump();
+                *at_end = true;
+                None
+            }
+            token::OpenDelim(token::Brace) => {
+                debug!("parse_trait_method_body(): parsing provided method");
+                *at_end = true;
+                let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
+                attrs.extend(inner_attrs.iter().cloned());
+                Some(body)
+            }
+            token::Interpolated(ref nt) => {
+                match **nt {
+                    token::NtBlock(..) => {
+                        *at_end = true;
+                        let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
+                        attrs.extend(inner_attrs.iter().cloned());
+                        Some(body)
+                    }
+                    _ => return self.expected_semi_or_open_brace(),
+                }
+            }
+            _ => return self.expected_semi_or_open_brace(),
+        })
+    }
+
+    /// Parse the "signature", including the identifier, parameters, and generics
+    /// of a method. The body is not parsed as that differs between `trait`s and `impl`s.
+    fn parse_method_sig(
+        &mut self,
+        is_name_required: fn(&token::Token) -> bool,
+    ) -> PResult<'a, (Ident, FnSig, Generics)> {
+        let header = self.parse_fn_front_matter()?;
+        let (ident, decl, generics) = self.parse_fn_sig(ParamCfg {
+            is_self_allowed: true,
+            allow_c_variadic: false,
+            is_name_required,
+        })?;
+        Ok((ident, FnSig { header, decl }, generics))
+    }
+
+    /// Parses all the "front matter" for a `fn` declaration, up to
+    /// and including the `fn` keyword:
+    ///
+    /// - `const fn`
+    /// - `unsafe fn`
+    /// - `const unsafe fn`
+    /// - `extern fn`
+    /// - etc.
+    fn parse_fn_front_matter(&mut self) -> PResult<'a, FnHeader> {
+        let is_const_fn = self.eat_keyword(kw::Const);
+        let const_span = self.prev_span;
+        let asyncness = self.parse_asyncness();
+        if let IsAsync::Async { .. } = asyncness {
+            self.ban_async_in_2015(self.prev_span);
+        }
+        let asyncness = respan(self.prev_span, asyncness);
+        let unsafety = self.parse_unsafety();
+        let (constness, unsafety, abi) = if is_const_fn {
+            (respan(const_span, Constness::Const), unsafety, Abi::default())
+        } else {
+            let abi = self.parse_extern_abi()?;
+            (respan(self.prev_span, Constness::NotConst), unsafety, abi)
+        };
+        if !self.eat_keyword(kw::Fn) {
+            // It is possible for `expect_one_of` to recover given the contents of
+            // `self.expected_tokens`, therefore, do not use `self.unexpected()` which doesn't
+            // account for this.
+            if !self.expect_one_of(&[], &[])? { unreachable!() }
+        }
+        Ok(FnHeader { constness, unsafety, asyncness, abi })
+    }
+
+    /// Parse the "signature", including the identifier, parameters, and generics of a function.
+    fn parse_fn_sig(&mut self, cfg: ParamCfg) -> PResult<'a, (Ident, P<FnDecl>, Generics)> {
+        let ident = self.parse_ident()?;
+        let mut generics = self.parse_generics()?;
+        let decl = self.parse_fn_decl(cfg, true)?;
+        generics.where_clause = self.parse_where_clause()?;
+        Ok((ident, decl, generics))
+    }
+
+    /// Parses the parameter list and result type of a function declaration.
+    pub(super) fn parse_fn_decl(
+        &mut self,
+        cfg: ParamCfg,
+        ret_allow_plus: bool,
+    ) -> PResult<'a, P<FnDecl>> {
+        Ok(P(FnDecl {
+            inputs: self.parse_fn_params(cfg)?,
+            output: self.parse_ret_ty(ret_allow_plus)?,
+        }))
+    }
+
+    /// Parses the parameter list of a function, including the `(` and `)` delimiters.
+    fn parse_fn_params(&mut self, mut cfg: ParamCfg) -> PResult<'a, Vec<Param>> {
+        let sp = self.token.span;
+        let is_trait_item = cfg.is_self_allowed;
+        let mut c_variadic = false;
+        // Parse the arguments, starting out with `self` being possibly allowed...
+        let (params, _) = self.parse_paren_comma_seq(|p| {
+            let param = p.parse_param_general(&cfg, is_trait_item);
+            // ...now that we've parsed the first argument, `self` is no longer allowed.
+            cfg.is_self_allowed = false;
+
+            match param {
+                Ok(param) => Ok(
+                    if let TyKind::CVarArgs = param.ty.kind {
+                        c_variadic = true;
+                        if p.token != token::CloseDelim(token::Paren) {
+                            p.span_err(
+                                p.token.span,
+                                "`...` must be the last argument of a C-variadic function",
+                            );
+                            // FIXME(eddyb) this should probably still push `CVarArgs`.
+                            // Maybe AST validation/HIR lowering should emit the above error?
+                            None
+                        } else {
+                            Some(param)
+                        }
+                    } else {
+                        Some(param)
+                    }
+                ),
+                Err(mut e) => {
+                    e.emit();
+                    let lo = p.prev_span;
+                    // Skip every token until next possible arg or end.
+                    p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]);
+                    // Create a placeholder argument for proper arg count (issue #34264).
+                    let span = lo.to(p.prev_span);
+                    Ok(Some(dummy_arg(Ident::new(kw::Invalid, span))))
+                }
+            }
+        })?;
+
+        let mut params: Vec<_> = params.into_iter().filter_map(|x| x).collect();
+
+        // Replace duplicated recovered params with `_` pattern to avoid unecessary errors.
+        self.deduplicate_recovered_params_names(&mut params);
+
+        if c_variadic && params.len() <= 1 {
+            self.span_err(
+                sp,
+                "C-variadic function must be declared with at least one named argument",
+            );
+        }
+
+        Ok(params)
+    }
+
+    /// Skips unexpected attributes and doc comments in this position and emits an appropriate
+    /// error.
+    /// This version of parse param doesn't necessarily require identifier names.
+    fn parse_param_general(&mut self, cfg: &ParamCfg, is_trait_item: bool) -> PResult<'a, Param> {
+        let lo = self.token.span;
+        let attrs = self.parse_outer_attributes()?;
+
+        // Possibly parse `self`. Recover if we parsed it and it wasn't allowed here.
+        if let Some(mut param) = self.parse_self_param()? {
+            param.attrs = attrs.into();
+            return if cfg.is_self_allowed {
+                Ok(param)
+            } else {
+                self.recover_bad_self_param(param, is_trait_item)
+            };
+        }
+
+        let is_name_required = match self.token.kind {
+            token::DotDotDot => false,
+            _ => (cfg.is_name_required)(&self.token),
+        };
+        let (pat, ty) = if is_name_required || self.is_named_param() {
+            debug!("parse_param_general parse_pat (is_name_required:{})", is_name_required);
+
+            let pat = self.parse_fn_param_pat()?;
+            if let Err(mut err) = self.expect(&token::Colon) {
+                return if let Some(ident) = self.parameter_without_type(
+                    &mut err,
+                    pat,
+                    is_name_required,
+                    cfg.is_self_allowed,
+                    is_trait_item,
+                ) {
+                    err.emit();
+                    Ok(dummy_arg(ident))
+                } else {
+                    Err(err)
+                };
+            }
+
+            self.eat_incorrect_doc_comment_for_param_type();
+            (pat, self.parse_ty_common(true, true, cfg.allow_c_variadic)?)
+        } else {
+            debug!("parse_param_general ident_to_pat");
+            let parser_snapshot_before_ty = self.clone();
+            self.eat_incorrect_doc_comment_for_param_type();
+            let mut ty = self.parse_ty_common(true, true, cfg.allow_c_variadic);
+            if ty.is_ok() && self.token != token::Comma &&
+               self.token != token::CloseDelim(token::Paren) {
+                // This wasn't actually a type, but a pattern looking like a type,
+                // so we are going to rollback and re-parse for recovery.
+                ty = self.unexpected();
+            }
+            match ty {
+                Ok(ty) => {
+                    let ident = Ident::new(kw::Invalid, self.prev_span);
+                    let bm = BindingMode::ByValue(Mutability::Immutable);
+                    let pat = self.mk_pat_ident(ty.span, bm, ident);
+                    (pat, ty)
+                }
+                // If this is a C-variadic argument and we hit an error, return the error.
+                Err(err) if self.token == token::DotDotDot => return Err(err),
+                // Recover from attempting to parse the argument as a type without pattern.
+                Err(mut err) => {
+                    err.cancel();
+                    mem::replace(self, parser_snapshot_before_ty);
+                    self.recover_arg_parse()?
+                }
+            }
+        };
+
+        let span = lo.to(self.token.span);
+
+        Ok(Param {
+            attrs: attrs.into(),
+            id: ast::DUMMY_NODE_ID,
+            is_placeholder: false,
+            pat,
+            span,
+            ty,
+        })
+    }
+
+    /// Returns the parsed optional self parameter and whether a self shortcut was used.
+    ///
+    /// See `parse_self_param_with_attrs` to collect attributes.
+    fn parse_self_param(&mut self) -> PResult<'a, Option<Param>> {
+        // Extract an identifier *after* having confirmed that the token is one.
+        let expect_self_ident = |this: &mut Self| {
+            match this.token.kind {
+                // Preserve hygienic context.
+                token::Ident(name, _) => {
+                    let span = this.token.span;
+                    this.bump();
+                    Ident::new(name, span)
+                }
+                _ => unreachable!(),
+            }
+        };
+        // Is `self` `n` tokens ahead?
+        let is_isolated_self = |this: &Self, n| {
+            this.is_keyword_ahead(n, &[kw::SelfLower])
+            && this.look_ahead(n + 1, |t| t != &token::ModSep)
+        };
+        // Is `mut self` `n` tokens ahead?
+        let is_isolated_mut_self = |this: &Self, n| {
+            this.is_keyword_ahead(n, &[kw::Mut])
+            && is_isolated_self(this, n + 1)
+        };
+        // Parse `self` or `self: TYPE`. We already know the current token is `self`.
+        let parse_self_possibly_typed = |this: &mut Self, m| {
+            let eself_ident = expect_self_ident(this);
+            let eself_hi = this.prev_span;
+            let eself = if this.eat(&token::Colon) {
+                SelfKind::Explicit(this.parse_ty()?, m)
+            } else {
+                SelfKind::Value(m)
+            };
+            Ok((eself, eself_ident, eself_hi))
+        };
+        // Recover for the grammar `*self`, `*const self`, and `*mut self`.
+        let recover_self_ptr = |this: &mut Self| {
+            let msg = "cannot pass `self` by raw pointer";
+            let span = this.token.span;
+            this.struct_span_err(span, msg)
+                .span_label(span, msg)
+                .emit();
+
+            Ok((SelfKind::Value(Mutability::Immutable), expect_self_ident(this), this.prev_span))
+        };
+
+        // Parse optional `self` parameter of a method.
+        // Only a limited set of initial token sequences is considered `self` parameters; anything
+        // else is parsed as a normal function parameter list, so some lookahead is required.
+        let eself_lo = self.token.span;
+        let (eself, eself_ident, eself_hi) = match self.token.kind {
+            token::BinOp(token::And) => {
+                let eself = if is_isolated_self(self, 1) {
+                    // `&self`
+                    self.bump();
+                    SelfKind::Region(None, Mutability::Immutable)
+                } else if is_isolated_mut_self(self, 1) {
+                    // `&mut self`
+                    self.bump();
+                    self.bump();
+                    SelfKind::Region(None, Mutability::Mutable)
+                } else if self.look_ahead(1, |t| t.is_lifetime()) && is_isolated_self(self, 2) {
+                    // `&'lt self`
+                    self.bump();
+                    let lt = self.expect_lifetime();
+                    SelfKind::Region(Some(lt), Mutability::Immutable)
+                } else if self.look_ahead(1, |t| t.is_lifetime()) && is_isolated_mut_self(self, 2) {
+                    // `&'lt mut self`
+                    self.bump();
+                    let lt = self.expect_lifetime();
+                    self.bump();
+                    SelfKind::Region(Some(lt), Mutability::Mutable)
+                } else {
+                    // `&not_self`
+                    return Ok(None);
+                };
+                (eself, expect_self_ident(self), self.prev_span)
+            }
+            // `*self`
+            token::BinOp(token::Star) if is_isolated_self(self, 1) => {
+                self.bump();
+                recover_self_ptr(self)?
+            }
+            // `*mut self` and `*const self`
+            token::BinOp(token::Star) if
+                self.look_ahead(1, |t| t.is_mutability())
+                && is_isolated_self(self, 2) =>
+            {
+                self.bump();
+                self.bump();
+                recover_self_ptr(self)?
+            }
+            // `self` and `self: TYPE`
+            token::Ident(..) if is_isolated_self(self, 0) => {
+                parse_self_possibly_typed(self, Mutability::Immutable)?
+            }
+            // `mut self` and `mut self: TYPE`
+            token::Ident(..) if is_isolated_mut_self(self, 0) => {
+                self.bump();
+                parse_self_possibly_typed(self, Mutability::Mutable)?
+            }
+            _ => return Ok(None),
+        };
+
+        let eself = source_map::respan(eself_lo.to(eself_hi), eself);
+        Ok(Some(Param::from_self(ThinVec::default(), eself, eself_ident)))
+    }
+
+    fn is_named_param(&self) -> bool {
+        let offset = match self.token.kind {
+            token::Interpolated(ref nt) => match **nt {
+                token::NtPat(..) => return self.look_ahead(1, |t| t == &token::Colon),
+                _ => 0,
+            }
+            token::BinOp(token::And) | token::AndAnd => 1,
+            _ if self.token.is_keyword(kw::Mut) => 1,
+            _ => 0,
+        };
+
+        self.look_ahead(offset, |t| t.is_ident()) &&
+        self.look_ahead(offset + 1, |t| t == &token::Colon)
+    }
+
+    fn recover_first_param(&mut self) -> &'static str {
+        match self.parse_outer_attributes()
+            .and_then(|_| self.parse_self_param())
+            .map_err(|mut e| e.cancel())
+        {
+            Ok(Some(_)) => "method",
+            _ => "function",
+        }
+    }
+}
diff --git a/src/librustc_parse/parser/mod.rs b/src/librustc_parse/parser/mod.rs
new file mode 100644
index 00000000000..a491d91e20f
--- /dev/null
+++ b/src/librustc_parse/parser/mod.rs
@@ -0,0 +1,1393 @@
+pub mod attr;
+mod expr;
+mod pat;
+mod item;
+mod module;
+mod ty;
+mod path;
+pub use path::PathStyle;
+mod stmt;
+mod generics;
+mod diagnostics;
+use diagnostics::Error;
+
+use crate::{Directory, DirectoryOwnership};
+use crate::lexer::UnmatchedBrace;
+
+use syntax::ast::{
+    self, Abi, DUMMY_NODE_ID, AttrStyle, Attribute, CrateSugar, Ident,
+    IsAsync, MacDelimiter, Mutability, StrStyle, Visibility, VisibilityKind, Unsafety,
+};
+
+use syntax::print::pprust;
+use syntax::ptr::P;
+use syntax::token::{self, Token, TokenKind, DelimToken};
+use syntax::tokenstream::{self, DelimSpan, TokenTree, TokenStream, TreeAndJoint};
+use syntax::sess::ParseSess;
+use syntax::source_map::respan;
+use syntax::struct_span_err;
+use syntax::util::comments::{doc_comment_style, strip_doc_comment_decoration};
+use syntax_pos::symbol::{kw, sym, Symbol};
+use syntax_pos::{Span, BytePos, DUMMY_SP, FileName};
+use rustc_data_structures::thin_vec::ThinVec;
+use errors::{PResult, Applicability, DiagnosticBuilder, DiagnosticId, FatalError};
+use log::debug;
+
+use std::borrow::Cow;
+use std::{cmp, mem, slice};
+use std::path::PathBuf;
+
+bitflags::bitflags! {
+    struct Restrictions: u8 {
+        const STMT_EXPR         = 1 << 0;
+        const NO_STRUCT_LITERAL = 1 << 1;
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Debug)]
+enum SemiColonMode {
+    Break,
+    Ignore,
+    Comma,
+}
+
+#[derive(Clone, Copy, PartialEq, Debug)]
+enum BlockMode {
+    Break,
+    Ignore,
+}
+
+/// Like `maybe_whole_expr`, but for things other than expressions.
+#[macro_export]
+macro_rules! maybe_whole {
+    ($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
+        if let token::Interpolated(nt) = &$p.token.kind {
+            if let token::$constructor(x) = &**nt {
+                let $x = x.clone();
+                $p.bump();
+                return Ok($e);
+            }
+        }
+    };
+}
+
+/// If the next tokens are ill-formed `$ty::` recover them as `<$ty>::`.
+#[macro_export]
+macro_rules! maybe_recover_from_interpolated_ty_qpath {
+    ($self: expr, $allow_qpath_recovery: expr) => {
+        if $allow_qpath_recovery && $self.look_ahead(1, |t| t == &token::ModSep) {
+            if let token::Interpolated(nt) = &$self.token.kind {
+                if let token::NtTy(ty) = &**nt {
+                    let ty = ty.clone();
+                    $self.bump();
+                    return $self.maybe_recover_from_bad_qpath_stage_2($self.prev_span, ty);
+                }
+            }
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+enum PrevTokenKind {
+    DocComment,
+    Comma,
+    Plus,
+    Interpolated,
+    Eof,
+    Ident,
+    BitOr,
+    Other,
+}
+
+// NOTE: `Ident`s are handled by `common.rs`.
+
+#[derive(Clone)]
+pub struct Parser<'a> {
+    pub sess: &'a ParseSess,
+    /// The current normalized token.
+    /// "Normalized" means that some interpolated tokens
+    /// (`$i: ident` and `$l: lifetime` meta-variables) are replaced
+    /// with non-interpolated identifier and lifetime tokens they refer to.
+    /// Perhaps the normalized / non-normalized setup can be simplified somehow.
+    pub token: Token,
+    /// The span of the current non-normalized token.
+    meta_var_span: Option<Span>,
+    /// The span of the previous non-normalized token.
+    pub prev_span: Span,
+    /// The kind of the previous normalized token (in simplified form).
+    prev_token_kind: PrevTokenKind,
+    restrictions: Restrictions,
+    /// Used to determine the path to externally loaded source files.
+    pub(super) directory: Directory<'a>,
+    /// `true` to parse sub-modules in other files.
+    pub(super) recurse_into_file_modules: bool,
+    /// Name of the root module this parser originated from. If `None`, then the
+    /// name is not known. This does not change while the parser is descending
+    /// into modules, and sub-parsers have new values for this name.
+    pub root_module_name: Option<String>,
+    expected_tokens: Vec<TokenType>,
+    token_cursor: TokenCursor,
+    desugar_doc_comments: bool,
+    /// `true` we should configure out of line modules as we parse.
+    cfg_mods: bool,
+    /// This field is used to keep track of how many left angle brackets we have seen. This is
+    /// required in order to detect extra leading left angle brackets (`<` characters) and error
+    /// appropriately.
+    ///
+    /// See the comments in the `parse_path_segment` function for more details.
+    unmatched_angle_bracket_count: u32,
+    max_angle_bracket_count: u32,
+    /// A list of all unclosed delimiters found by the lexer. If an entry is used for error recovery
+    /// it gets removed from here. Every entry left at the end gets emitted as an independent
+    /// error.
+    pub(super) unclosed_delims: Vec<UnmatchedBrace>,
+    last_unexpected_token_span: Option<Span>,
+    pub last_type_ascription: Option<(Span, bool /* likely path typo */)>,
+    /// If present, this `Parser` is not parsing Rust code but rather a macro call.
+    subparser_name: Option<&'static str>,
+}
+
+impl<'a> Drop for Parser<'a> {
+    fn drop(&mut self) {
+        emit_unclosed_delims(&mut self.unclosed_delims, &self.sess);
+    }
+}
+
+#[derive(Clone)]
+struct TokenCursor {
+    frame: TokenCursorFrame,
+    stack: Vec<TokenCursorFrame>,
+}
+
+#[derive(Clone)]
+struct TokenCursorFrame {
+    delim: token::DelimToken,
+    span: DelimSpan,
+    open_delim: bool,
+    tree_cursor: tokenstream::Cursor,
+    close_delim: bool,
+    last_token: LastToken,
+}
+
+/// This is used in `TokenCursorFrame` above to track tokens that are consumed
+/// by the parser, and then that's transitively used to record the tokens that
+/// each parse AST item is created with.
+///
+/// Right now this has two states, either collecting tokens or not collecting
+/// tokens. If we're collecting tokens we just save everything off into a local
+/// `Vec`. This should eventually though likely save tokens from the original
+/// token stream and just use slicing of token streams to avoid creation of a
+/// whole new vector.
+///
+/// The second state is where we're passively not recording tokens, but the last
+/// token is still tracked for when we want to start recording tokens. This
+/// "last token" means that when we start recording tokens we'll want to ensure
+/// that this, the first token, is included in the output.
+///
+/// You can find some more example usage of this in the `collect_tokens` method
+/// on the parser.
+#[derive(Clone)]
+enum LastToken {
+    Collecting(Vec<TreeAndJoint>),
+    Was(Option<TreeAndJoint>),
+}
+
+impl TokenCursorFrame {
+    fn new(span: DelimSpan, delim: DelimToken, tts: &TokenStream) -> Self {
+        TokenCursorFrame {
+            delim,
+            span,
+            open_delim: delim == token::NoDelim,
+            tree_cursor: tts.clone().into_trees(),
+            close_delim: delim == token::NoDelim,
+            last_token: LastToken::Was(None),
+        }
+    }
+}
+
+impl TokenCursor {
+    fn next(&mut self) -> Token {
+        loop {
+            let tree = if !self.frame.open_delim {
+                self.frame.open_delim = true;
+                TokenTree::open_tt(self.frame.span, self.frame.delim)
+            } else if let Some(tree) = self.frame.tree_cursor.next() {
+                tree
+            } else if !self.frame.close_delim {
+                self.frame.close_delim = true;
+                TokenTree::close_tt(self.frame.span, self.frame.delim)
+            } else if let Some(frame) = self.stack.pop() {
+                self.frame = frame;
+                continue
+            } else {
+                return Token::new(token::Eof, DUMMY_SP);
+            };
+
+            match self.frame.last_token {
+                LastToken::Collecting(ref mut v) => v.push(tree.clone().into()),
+                LastToken::Was(ref mut t) => *t = Some(tree.clone().into()),
+            }
+
+            match tree {
+                TokenTree::Token(token) => return token,
+                TokenTree::Delimited(sp, delim, tts) => {
+                    let frame = TokenCursorFrame::new(sp, delim, &tts);
+                    self.stack.push(mem::replace(&mut self.frame, frame));
+                }
+            }
+        }
+    }
+
+    fn next_desugared(&mut self) -> Token {
+        let (name, sp) = match self.next() {
+            Token { kind: token::DocComment(name), span } => (name, span),
+            tok => return tok,
+        };
+
+        let stripped = strip_doc_comment_decoration(&name.as_str());
+
+        // Searches for the occurrences of `"#*` and returns the minimum number of `#`s
+        // required to wrap the text.
+        let mut num_of_hashes = 0;
+        let mut count = 0;
+        for ch in stripped.chars() {
+            count = match ch {
+                '"' => 1,
+                '#' if count > 0 => count + 1,
+                _ => 0,
+            };
+            num_of_hashes = cmp::max(num_of_hashes, count);
+        }
+
+        let delim_span = DelimSpan::from_single(sp);
+        let body = TokenTree::Delimited(
+            delim_span,
+            token::Bracket,
+            [
+                TokenTree::token(token::Ident(sym::doc, false), sp),
+                TokenTree::token(token::Eq, sp),
+                TokenTree::token(TokenKind::lit(
+                    token::StrRaw(num_of_hashes), Symbol::intern(&stripped), None
+                ), sp),
+            ]
+            .iter().cloned().collect::<TokenStream>().into(),
+        );
+
+        self.stack.push(mem::replace(&mut self.frame, TokenCursorFrame::new(
+            delim_span,
+            token::NoDelim,
+            &if doc_comment_style(&name.as_str()) == AttrStyle::Inner {
+                [TokenTree::token(token::Pound, sp), TokenTree::token(token::Not, sp), body]
+                    .iter().cloned().collect::<TokenStream>()
+            } else {
+                [TokenTree::token(token::Pound, sp), body]
+                    .iter().cloned().collect::<TokenStream>()
+            },
+        )));
+
+        self.next()
+    }
+}
+
+#[derive(Clone, PartialEq)]
+enum TokenType {
+    Token(TokenKind),
+    Keyword(Symbol),
+    Operator,
+    Lifetime,
+    Ident,
+    Path,
+    Type,
+    Const,
+}
+
+impl TokenType {
+    fn to_string(&self) -> String {
+        match *self {
+            TokenType::Token(ref t) => format!("`{}`", pprust::token_kind_to_string(t)),
+            TokenType::Keyword(kw) => format!("`{}`", kw),
+            TokenType::Operator => "an operator".to_string(),
+            TokenType::Lifetime => "lifetime".to_string(),
+            TokenType::Ident => "identifier".to_string(),
+            TokenType::Path => "path".to_string(),
+            TokenType::Type => "type".to_string(),
+            TokenType::Const => "const".to_string(),
+        }
+    }
+}
+
+#[derive(Copy, Clone, Debug)]
+enum TokenExpectType {
+    Expect,
+    NoExpect,
+}
+
+/// A sequence separator.
+struct SeqSep {
+    /// The separator token.
+    sep: Option<TokenKind>,
+    /// `true` if a trailing separator is allowed.
+    trailing_sep_allowed: bool,
+}
+
+impl SeqSep {
+    fn trailing_allowed(t: TokenKind) -> SeqSep {
+        SeqSep {
+            sep: Some(t),
+            trailing_sep_allowed: true,
+        }
+    }
+
+    fn none() -> SeqSep {
+        SeqSep {
+            sep: None,
+            trailing_sep_allowed: false,
+        }
+    }
+}
+
+impl<'a> Parser<'a> {
+    pub fn new(
+        sess: &'a ParseSess,
+        tokens: TokenStream,
+        directory: Option<Directory<'a>>,
+        recurse_into_file_modules: bool,
+        desugar_doc_comments: bool,
+        subparser_name: Option<&'static str>,
+    ) -> Self {
+        let mut parser = Parser {
+            sess,
+            token: Token::dummy(),
+            prev_span: DUMMY_SP,
+            meta_var_span: None,
+            prev_token_kind: PrevTokenKind::Other,
+            restrictions: Restrictions::empty(),
+            recurse_into_file_modules,
+            directory: Directory {
+                path: Cow::from(PathBuf::new()),
+                ownership: DirectoryOwnership::Owned { relative: None }
+            },
+            root_module_name: None,
+            expected_tokens: Vec::new(),
+            token_cursor: TokenCursor {
+                frame: TokenCursorFrame::new(
+                    DelimSpan::dummy(),
+                    token::NoDelim,
+                    &tokens.into(),
+                ),
+                stack: Vec::new(),
+            },
+            desugar_doc_comments,
+            cfg_mods: true,
+            unmatched_angle_bracket_count: 0,
+            max_angle_bracket_count: 0,
+            unclosed_delims: Vec::new(),
+            last_unexpected_token_span: None,
+            last_type_ascription: None,
+            subparser_name,
+        };
+
+        parser.token = parser.next_tok();
+
+        if let Some(directory) = directory {
+            parser.directory = directory;
+        } else if !parser.token.span.is_dummy() {
+            if let Some(FileName::Real(path)) =
+                    &sess.source_map().lookup_char_pos(parser.token.span.lo()).file.unmapped_path {
+                if let Some(directory_path) = path.parent() {
+                    parser.directory.path = Cow::from(directory_path.to_path_buf());
+                }
+            }
+        }
+
+        parser.process_potential_macro_variable();
+        parser
+    }
+
+    fn next_tok(&mut self) -> Token {
+        let mut next = if self.desugar_doc_comments {
+            self.token_cursor.next_desugared()
+        } else {
+            self.token_cursor.next()
+        };
+        if next.span.is_dummy() {
+            // Tweak the location for better diagnostics, but keep syntactic context intact.
+            next.span = self.prev_span.with_ctxt(next.span.ctxt());
+        }
+        next
+    }
+
+    /// Converts the current token to a string using `self`'s reader.
+    pub fn this_token_to_string(&self) -> String {
+        pprust::token_to_string(&self.token)
+    }
+
+    fn token_descr(&self) -> Option<&'static str> {
+        Some(match &self.token.kind {
+            _ if self.token.is_special_ident() => "reserved identifier",
+            _ if self.token.is_used_keyword() => "keyword",
+            _ if self.token.is_unused_keyword() => "reserved keyword",
+            token::DocComment(..) => "doc comment",
+            _ => return None,
+        })
+    }
+
+    pub(super) fn this_token_descr(&self) -> String {
+        if let Some(prefix) = self.token_descr() {
+            format!("{} `{}`", prefix, self.this_token_to_string())
+        } else {
+            format!("`{}`", self.this_token_to_string())
+        }
+    }
+
+    crate fn unexpected<T>(&mut self) -> PResult<'a, T> {
+        match self.expect_one_of(&[], &[]) {
+            Err(e) => Err(e),
+            Ok(_) => unreachable!(),
+        }
+    }
+
+    /// Expects and consumes the token `t`. Signals an error if the next token is not `t`.
+    pub fn expect(&mut self, t: &TokenKind) -> PResult<'a, bool /* recovered */> {
+        if self.expected_tokens.is_empty() {
+            if self.token == *t {
+                self.bump();
+                Ok(false)
+            } else {
+                self.unexpected_try_recover(t)
+            }
+        } else {
+            self.expect_one_of(slice::from_ref(t), &[])
+        }
+    }
+
+    /// Expect next token to be edible or inedible token.  If edible,
+    /// then consume it; if inedible, then return without consuming
+    /// anything.  Signal a fatal error if next token is unexpected.
+    pub fn expect_one_of(
+        &mut self,
+        edible: &[TokenKind],
+        inedible: &[TokenKind],
+    ) -> PResult<'a, bool /* recovered */> {
+        if edible.contains(&self.token.kind) {
+            self.bump();
+            Ok(false)
+        } else if inedible.contains(&self.token.kind) {
+            // leave it in the input
+            Ok(false)
+        } else if self.last_unexpected_token_span == Some(self.token.span) {
+            FatalError.raise();
+        } else {
+            self.expected_one_of_not_found(edible, inedible)
+        }
+    }
+
+    fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
+        self.parse_ident_common(true)
+    }
+
+    fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, ast::Ident> {
+        match self.token.kind {
+            token::Ident(name, _) => {
+                if self.token.is_reserved_ident() {
+                    let mut err = self.expected_ident_found();
+                    if recover {
+                        err.emit();
+                    } else {
+                        return Err(err);
+                    }
+                }
+                let span = self.token.span;
+                self.bump();
+                Ok(Ident::new(name, span))
+            }
+            _ => {
+                Err(if self.prev_token_kind == PrevTokenKind::DocComment {
+                    self.span_fatal_err(self.prev_span, Error::UselessDocComment)
+                } else {
+                    self.expected_ident_found()
+                })
+            }
+        }
+    }
+
+    /// Checks if the next token is `tok`, and returns `true` if so.
+    ///
+    /// This method will automatically add `tok` to `expected_tokens` if `tok` is not
+    /// encountered.
+    fn check(&mut self, tok: &TokenKind) -> bool {
+        let is_present = self.token == *tok;
+        if !is_present { self.expected_tokens.push(TokenType::Token(tok.clone())); }
+        is_present
+    }
+
+    /// Consumes a token 'tok' if it exists. Returns whether the given token was present.
+    pub fn eat(&mut self, tok: &TokenKind) -> bool {
+        let is_present = self.check(tok);
+        if is_present { self.bump() }
+        is_present
+    }
+
+    /// If the next token is the given keyword, returns `true` without eating it.
+    /// An expectation is also added for diagnostics purposes.
+    fn check_keyword(&mut self, kw: Symbol) -> bool {
+        self.expected_tokens.push(TokenType::Keyword(kw));
+        self.token.is_keyword(kw)
+    }
+
+    /// If the next token is the given keyword, eats it and returns `true`.
+    /// Otherwise, returns `false`. An expectation is also added for diagnostics purposes.
+    fn eat_keyword(&mut self, kw: Symbol) -> bool {
+        if self.check_keyword(kw) {
+            self.bump();
+            true
+        } else {
+            false
+        }
+    }
+
+    fn eat_keyword_noexpect(&mut self, kw: Symbol) -> bool {
+        if self.token.is_keyword(kw) {
+            self.bump();
+            true
+        } else {
+            false
+        }
+    }
+
+    /// If the given word is not a keyword, signals an error.
+    /// If the next token is not the given word, signals an error.
+    /// Otherwise, eats it.
+    fn expect_keyword(&mut self, kw: Symbol) -> PResult<'a, ()> {
+        if !self.eat_keyword(kw) {
+            self.unexpected()
+        } else {
+            Ok(())
+        }
+    }
+
+    fn check_or_expected(&mut self, ok: bool, typ: TokenType) -> bool {
+        if ok {
+            true
+        } else {
+            self.expected_tokens.push(typ);
+            false
+        }
+    }
+
+    fn check_ident(&mut self) -> bool {
+        self.check_or_expected(self.token.is_ident(), TokenType::Ident)
+    }
+
+    fn check_path(&mut self) -> bool {
+        self.check_or_expected(self.token.is_path_start(), TokenType::Path)
+    }
+
+    fn check_type(&mut self) -> bool {
+        self.check_or_expected(self.token.can_begin_type(), TokenType::Type)
+    }
+
+    fn check_const_arg(&mut self) -> bool {
+        self.check_or_expected(self.token.can_begin_const_arg(), TokenType::Const)
+    }
+
+    /// Checks to see if the next token is either `+` or `+=`.
+    /// Otherwise returns `false`.
+    fn check_plus(&mut self) -> bool {
+        self.check_or_expected(
+            self.token.is_like_plus(),
+            TokenType::Token(token::BinOp(token::Plus)),
+        )
+    }
+
+    /// Expects and consumes a `+`. if `+=` is seen, replaces it with a `=`
+    /// and continues. If a `+` is not seen, returns `false`.
+    ///
+    /// This is used when token-splitting `+=` into `+`.
+    /// See issue #47856 for an example of when this may occur.
+    fn eat_plus(&mut self) -> bool {
+        self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus)));
+        match self.token.kind {
+            token::BinOp(token::Plus) => {
+                self.bump();
+                true
+            }
+            token::BinOpEq(token::Plus) => {
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
+                self.bump_with(token::Eq, span);
+                true
+            }
+            _ => false,
+        }
+    }
+
+    /// Expects and consumes an `&`. If `&&` is seen, replaces it with a single
+    /// `&` and continues. If an `&` is not seen, signals an error.
+    fn expect_and(&mut self) -> PResult<'a, ()> {
+        self.expected_tokens.push(TokenType::Token(token::BinOp(token::And)));
+        match self.token.kind {
+            token::BinOp(token::And) => {
+                self.bump();
+                Ok(())
+            }
+            token::AndAnd => {
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
+                Ok(self.bump_with(token::BinOp(token::And), span))
+            }
+            _ => self.unexpected()
+        }
+    }
+
+    /// Expects and consumes an `|`. If `||` is seen, replaces it with a single
+    /// `|` and continues. If an `|` is not seen, signals an error.
+    fn expect_or(&mut self) -> PResult<'a, ()> {
+        self.expected_tokens.push(TokenType::Token(token::BinOp(token::Or)));
+        match self.token.kind {
+            token::BinOp(token::Or) => {
+                self.bump();
+                Ok(())
+            }
+            token::OrOr => {
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
+                Ok(self.bump_with(token::BinOp(token::Or), span))
+            }
+            _ => self.unexpected()
+        }
+    }
+
+    /// Attempts to consume a `<`. If `<<` is seen, replaces it with a single
+    /// `<` and continue. If `<-` is seen, replaces it with a single `<`
+    /// and continue. If a `<` is not seen, returns false.
+    ///
+    /// This is meant to be used when parsing generics on a path to get the
+    /// starting token.
+    fn eat_lt(&mut self) -> bool {
+        self.expected_tokens.push(TokenType::Token(token::Lt));
+        let ate = match self.token.kind {
+            token::Lt => {
+                self.bump();
+                true
+            }
+            token::BinOp(token::Shl) => {
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
+                self.bump_with(token::Lt, span);
+                true
+            }
+            token::LArrow => {
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
+                self.bump_with(token::BinOp(token::Minus), span);
+                true
+            }
+            _ => false,
+        };
+
+        if ate {
+            // See doc comment for `unmatched_angle_bracket_count`.
+            self.unmatched_angle_bracket_count += 1;
+            self.max_angle_bracket_count += 1;
+            debug!("eat_lt: (increment) count={:?}", self.unmatched_angle_bracket_count);
+        }
+
+        ate
+    }
+
+    fn expect_lt(&mut self) -> PResult<'a, ()> {
+        if !self.eat_lt() {
+            self.unexpected()
+        } else {
+            Ok(())
+        }
+    }
+
+    /// Expects and consumes a single `>` token. if a `>>` is seen, replaces it
+    /// with a single `>` and continues. If a `>` is not seen, signals an error.
+    fn expect_gt(&mut self) -> PResult<'a, ()> {
+        self.expected_tokens.push(TokenType::Token(token::Gt));
+        let ate = match self.token.kind {
+            token::Gt => {
+                self.bump();
+                Some(())
+            }
+            token::BinOp(token::Shr) => {
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
+                Some(self.bump_with(token::Gt, span))
+            }
+            token::BinOpEq(token::Shr) => {
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
+                Some(self.bump_with(token::Ge, span))
+            }
+            token::Ge => {
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
+                Some(self.bump_with(token::Eq, span))
+            }
+            _ => None,
+        };
+
+        match ate {
+            Some(_) => {
+                // See doc comment for `unmatched_angle_bracket_count`.
+                if self.unmatched_angle_bracket_count > 0 {
+                    self.unmatched_angle_bracket_count -= 1;
+                    debug!("expect_gt: (decrement) count={:?}", self.unmatched_angle_bracket_count);
+                }
+
+                Ok(())
+            },
+            None => self.unexpected(),
+        }
+    }
+
+    /// Parses a sequence, including the closing delimiter. The function
+    /// `f` must consume tokens until reaching the next separator or
+    /// closing bracket.
+    fn parse_seq_to_end<T>(
+        &mut self,
+        ket: &TokenKind,
+        sep: SeqSep,
+        f: impl FnMut(&mut Parser<'a>) -> PResult<'a,  T>,
+    ) -> PResult<'a, Vec<T>> {
+        let (val, _, recovered) = self.parse_seq_to_before_end(ket, sep, f)?;
+        if !recovered {
+            self.bump();
+        }
+        Ok(val)
+    }
+
+    /// Parses a sequence, not including the closing delimiter. The function
+    /// `f` must consume tokens until reaching the next separator or
+    /// closing bracket.
+    fn parse_seq_to_before_end<T>(
+        &mut self,
+        ket: &TokenKind,
+        sep: SeqSep,
+        f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
+    ) -> PResult<'a, (Vec<T>, bool, bool)> {
+        self.parse_seq_to_before_tokens(&[ket], sep, TokenExpectType::Expect, f)
+    }
+
+    fn expect_any_with_type(&mut self, kets: &[&TokenKind], expect: TokenExpectType) -> bool {
+        kets.iter().any(|k| {
+            match expect {
+                TokenExpectType::Expect => self.check(k),
+                TokenExpectType::NoExpect => self.token == **k,
+            }
+        })
+    }
+
+    fn parse_seq_to_before_tokens<T>(
+        &mut self,
+        kets: &[&TokenKind],
+        sep: SeqSep,
+        expect: TokenExpectType,
+        mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
+    ) -> PResult<'a, (Vec<T>, bool /* trailing */, bool /* recovered */)> {
+        let mut first = true;
+        let mut recovered = false;
+        let mut trailing = false;
+        let mut v = vec![];
+        while !self.expect_any_with_type(kets, expect) {
+            if let token::CloseDelim(..) | token::Eof = self.token.kind {
+                break
+            }
+            if let Some(ref t) = sep.sep {
+                if first {
+                    first = false;
+                } else {
+                    match self.expect(t) {
+                        Ok(false) => {}
+                        Ok(true) => {
+                            recovered = true;
+                            break;
+                        }
+                        Err(mut e) => {
+                            // Attempt to keep parsing if it was a similar separator.
+                            if let Some(ref tokens) = t.similar_tokens() {
+                                if tokens.contains(&self.token.kind) {
+                                    self.bump();
+                                }
+                            }
+                            e.emit();
+                            // Attempt to keep parsing if it was an omitted separator.
+                            match f(self) {
+                                Ok(t) => {
+                                    v.push(t);
+                                    continue;
+                                },
+                                Err(mut e) => {
+                                    e.cancel();
+                                    break;
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+            if sep.trailing_sep_allowed && self.expect_any_with_type(kets, expect) {
+                trailing = true;
+                break;
+            }
+
+            let t = f(self)?;
+            v.push(t);
+        }
+
+        Ok((v, trailing, recovered))
+    }
+
+    /// Parses a sequence, including the closing delimiter. The function
+    /// `f` must consume tokens until reaching the next separator or
+    /// closing bracket.
+    fn parse_unspanned_seq<T>(
+        &mut self,
+        bra: &TokenKind,
+        ket: &TokenKind,
+        sep: SeqSep,
+        f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
+    ) -> PResult<'a, (Vec<T>, bool)> {
+        self.expect(bra)?;
+        let (result, trailing, recovered) = self.parse_seq_to_before_end(ket, sep, f)?;
+        if !recovered {
+            self.eat(ket);
+        }
+        Ok((result, trailing))
+    }
+
+    fn parse_delim_comma_seq<T>(
+        &mut self,
+        delim: DelimToken,
+        f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
+    ) -> PResult<'a, (Vec<T>, bool)> {
+        self.parse_unspanned_seq(
+            &token::OpenDelim(delim),
+            &token::CloseDelim(delim),
+            SeqSep::trailing_allowed(token::Comma),
+            f,
+        )
+    }
+
+    fn parse_paren_comma_seq<T>(
+        &mut self,
+        f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
+    ) -> PResult<'a, (Vec<T>, bool)> {
+        self.parse_delim_comma_seq(token::Paren, f)
+    }
+
+    /// Advance the parser by one token.
+    pub fn bump(&mut self) {
+        if self.prev_token_kind == PrevTokenKind::Eof {
+            // Bumping after EOF is a bad sign, usually an infinite loop.
+            self.bug("attempted to bump the parser past EOF (may be stuck in a loop)");
+        }
+
+        self.prev_span = self.meta_var_span.take().unwrap_or(self.token.span);
+
+        // Record last token kind for possible error recovery.
+        self.prev_token_kind = match self.token.kind {
+            token::DocComment(..) => PrevTokenKind::DocComment,
+            token::Comma => PrevTokenKind::Comma,
+            token::BinOp(token::Plus) => PrevTokenKind::Plus,
+            token::BinOp(token::Or) => PrevTokenKind::BitOr,
+            token::Interpolated(..) => PrevTokenKind::Interpolated,
+            token::Eof => PrevTokenKind::Eof,
+            token::Ident(..) => PrevTokenKind::Ident,
+            _ => PrevTokenKind::Other,
+        };
+
+        self.token = self.next_tok();
+        self.expected_tokens.clear();
+        // Check after each token.
+        self.process_potential_macro_variable();
+    }
+
+    /// Advances the parser using provided token as a next one. Use this when
+    /// consuming a part of a token. For example a single `<` from `<<`.
+    fn bump_with(&mut self, next: TokenKind, span: Span) {
+        self.prev_span = self.token.span.with_hi(span.lo());
+        // It would be incorrect to record the kind of the current token, but
+        // fortunately for tokens currently using `bump_with`, the
+        // `prev_token_kind` will be of no use anyway.
+        self.prev_token_kind = PrevTokenKind::Other;
+        self.token = Token::new(next, span);
+        self.expected_tokens.clear();
+    }
+
+    /// Look-ahead `dist` tokens of `self.token` and get access to that token there.
+    /// When `dist == 0` then the current token is looked at.
+    pub fn look_ahead<R>(&self, dist: usize, looker: impl FnOnce(&Token) -> R) -> R {
+        if dist == 0 {
+            return looker(&self.token);
+        }
+
+        let frame = &self.token_cursor.frame;
+        looker(&match frame.tree_cursor.look_ahead(dist - 1) {
+            Some(tree) => match tree {
+                TokenTree::Token(token) => token,
+                TokenTree::Delimited(dspan, delim, _) =>
+                    Token::new(token::OpenDelim(delim), dspan.open),
+            }
+            None => Token::new(token::CloseDelim(frame.delim), frame.span.close)
+        })
+    }
+
+    /// Returns whether any of the given keywords are `dist` tokens ahead of the current one.
+    fn is_keyword_ahead(&self, dist: usize, kws: &[Symbol]) -> bool {
+        self.look_ahead(dist, |t| kws.iter().any(|&kw| t.is_keyword(kw)))
+    }
+
+    /// Parses asyncness: `async` or nothing.
+    fn parse_asyncness(&mut self) -> IsAsync {
+        if self.eat_keyword(kw::Async) {
+            IsAsync::Async {
+                closure_id: DUMMY_NODE_ID,
+                return_impl_trait_id: DUMMY_NODE_ID,
+            }
+        } else {
+            IsAsync::NotAsync
+        }
+    }
+
+    /// Parses unsafety: `unsafe` or nothing.
+    fn parse_unsafety(&mut self) -> Unsafety {
+        if self.eat_keyword(kw::Unsafe) {
+            Unsafety::Unsafe
+        } else {
+            Unsafety::Normal
+        }
+    }
+
+    /// Parses mutability (`mut` or nothing).
+    fn parse_mutability(&mut self) -> Mutability {
+        if self.eat_keyword(kw::Mut) {
+            Mutability::Mutable
+        } else {
+            Mutability::Immutable
+        }
+    }
+
+    /// Possibly parses mutability (`const` or `mut`).
+    fn parse_const_or_mut(&mut self) -> Option<Mutability> {
+        if self.eat_keyword(kw::Mut) {
+            Some(Mutability::Mutable)
+        } else if self.eat_keyword(kw::Const) {
+            Some(Mutability::Immutable)
+        } else {
+            None
+        }
+    }
+
+    fn parse_field_name(&mut self) -> PResult<'a, Ident> {
+        if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) =
+                self.token.kind {
+            self.expect_no_suffix(self.token.span, "a tuple index", suffix);
+            self.bump();
+            Ok(Ident::new(symbol, self.prev_span))
+        } else {
+            self.parse_ident_common(false)
+        }
+    }
+
+    fn expect_delimited_token_tree(&mut self) -> PResult<'a, (MacDelimiter, TokenStream)> {
+        let delim = match self.token.kind {
+            token::OpenDelim(delim) => delim,
+            _ => {
+                let msg = "expected open delimiter";
+                let mut err = self.fatal(msg);
+                err.span_label(self.token.span, msg);
+                return Err(err)
+            }
+        };
+        let tts = match self.parse_token_tree() {
+            TokenTree::Delimited(_, _, tts) => tts,
+            _ => unreachable!(),
+        };
+        let delim = match delim {
+            token::Paren => MacDelimiter::Parenthesis,
+            token::Bracket => MacDelimiter::Bracket,
+            token::Brace => MacDelimiter::Brace,
+            token::NoDelim => self.bug("unexpected no delimiter"),
+        };
+        Ok((delim, tts.into()))
+    }
+
+    fn parse_or_use_outer_attributes(
+        &mut self,
+        already_parsed_attrs: Option<ThinVec<Attribute>>,
+    ) -> PResult<'a, ThinVec<Attribute>> {
+        if let Some(attrs) = already_parsed_attrs {
+            Ok(attrs)
+        } else {
+            self.parse_outer_attributes().map(|a| a.into())
+        }
+    }
+
+    pub fn process_potential_macro_variable(&mut self) {
+        self.token = match self.token.kind {
+            token::Dollar if self.token.span.from_expansion() &&
+                             self.look_ahead(1, |t| t.is_ident()) => {
+                self.bump();
+                let name = match self.token.kind {
+                    token::Ident(name, _) => name,
+                    _ => unreachable!()
+                };
+                let span = self.prev_span.to(self.token.span);
+                self.diagnostic()
+                    .struct_span_fatal(span, &format!("unknown macro variable `{}`", name))
+                    .span_label(span, "unknown macro variable")
+                    .emit();
+                self.bump();
+                return
+            }
+            token::Interpolated(ref nt) => {
+                self.meta_var_span = Some(self.token.span);
+                // Interpolated identifier and lifetime tokens are replaced with usual identifier
+                // and lifetime tokens, so the former are never encountered during normal parsing.
+                match **nt {
+                    token::NtIdent(ident, is_raw) =>
+                        Token::new(token::Ident(ident.name, is_raw), ident.span),
+                    token::NtLifetime(ident) =>
+                        Token::new(token::Lifetime(ident.name), ident.span),
+                    _ => return,
+                }
+            }
+            _ => return,
+        };
+    }
+
+    /// Parses a single token tree from the input.
+    pub fn parse_token_tree(&mut self) -> TokenTree {
+        match self.token.kind {
+            token::OpenDelim(..) => {
+                let frame = mem::replace(&mut self.token_cursor.frame,
+                                         self.token_cursor.stack.pop().unwrap());
+                self.token.span = frame.span.entire();
+                self.bump();
+                TokenTree::Delimited(
+                    frame.span,
+                    frame.delim,
+                    frame.tree_cursor.stream.into(),
+                )
+            },
+            token::CloseDelim(_) | token::Eof => unreachable!(),
+            _ => {
+                let token = self.token.take();
+                self.bump();
+                TokenTree::Token(token)
+            }
+        }
+    }
+
+    /// Parses a stream of tokens into a list of `TokenTree`s, up to EOF.
+    pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
+        let mut tts = Vec::new();
+        while self.token != token::Eof {
+            tts.push(self.parse_token_tree());
+        }
+        Ok(tts)
+    }
+
+    pub fn parse_tokens(&mut self) -> TokenStream {
+        let mut result = Vec::new();
+        loop {
+            match self.token.kind {
+                token::Eof | token::CloseDelim(..) => break,
+                _ => result.push(self.parse_token_tree().into()),
+            }
+        }
+        TokenStream::new(result)
+    }
+
+    /// Evaluates the closure with restrictions in place.
+    ///
+    /// Afters the closure is evaluated, restrictions are reset.
+    fn with_res<T>(&mut self, res: Restrictions, f: impl FnOnce(&mut Self) -> T) -> T {
+        let old = self.restrictions;
+        self.restrictions = res;
+        let res = f(self);
+        self.restrictions = old;
+        res
+    }
+
+    fn is_crate_vis(&self) -> bool {
+        self.token.is_keyword(kw::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
+    }
+
+    /// Parses `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `crate` for `pub(crate)`,
+    /// `pub(self)` for `pub(in self)` and `pub(super)` for `pub(in super)`.
+    /// If the following element can't be a tuple (i.e., it's a function definition), then
+    /// it's not a tuple struct field), and the contents within the parentheses isn't valid,
+    /// so emit a proper diagnostic.
+    pub fn parse_visibility(&mut self, can_take_tuple: bool) -> PResult<'a, Visibility> {
+        maybe_whole!(self, NtVis, |x| x);
+
+        self.expected_tokens.push(TokenType::Keyword(kw::Crate));
+        if self.is_crate_vis() {
+            self.bump(); // `crate`
+            self.sess.gated_spans.gate(sym::crate_visibility_modifier, self.prev_span);
+            return Ok(respan(self.prev_span, VisibilityKind::Crate(CrateSugar::JustCrate)));
+        }
+
+        if !self.eat_keyword(kw::Pub) {
+            // We need a span for our `Spanned<VisibilityKind>`, but there's inherently no
+            // keyword to grab a span from for inherited visibility; an empty span at the
+            // beginning of the current token would seem to be the "Schelling span".
+            return Ok(respan(self.token.span.shrink_to_lo(), VisibilityKind::Inherited))
+        }
+        let lo = self.prev_span;
+
+        if self.check(&token::OpenDelim(token::Paren)) {
+            // We don't `self.bump()` the `(` yet because this might be a struct definition where
+            // `()` or a tuple might be allowed. For example, `struct Struct(pub (), pub (usize));`.
+            // Because of this, we only `bump` the `(` if we're assured it is appropriate to do so
+            // by the following tokens.
+            if self.is_keyword_ahead(1, &[kw::Crate])
+                && self.look_ahead(2, |t| t != &token::ModSep) // account for `pub(crate::foo)`
+            {
+                // Parse `pub(crate)`.
+                self.bump(); // `(`
+                self.bump(); // `crate`
+                self.expect(&token::CloseDelim(token::Paren))?; // `)`
+                let vis = VisibilityKind::Crate(CrateSugar::PubCrate);
+                return Ok(respan(lo.to(self.prev_span), vis));
+            } else if self.is_keyword_ahead(1, &[kw::In]) {
+                // Parse `pub(in path)`.
+                self.bump(); // `(`
+                self.bump(); // `in`
+                let path = self.parse_path(PathStyle::Mod)?; // `path`
+                self.expect(&token::CloseDelim(token::Paren))?; // `)`
+                let vis = VisibilityKind::Restricted {
+                    path: P(path),
+                    id: ast::DUMMY_NODE_ID,
+                };
+                return Ok(respan(lo.to(self.prev_span), vis));
+            } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren))
+                && self.is_keyword_ahead(1, &[kw::Super, kw::SelfLower])
+            {
+                // Parse `pub(self)` or `pub(super)`.
+                self.bump(); // `(`
+                let path = self.parse_path(PathStyle::Mod)?; // `super`/`self`
+                self.expect(&token::CloseDelim(token::Paren))?; // `)`
+                let vis = VisibilityKind::Restricted {
+                    path: P(path),
+                    id: ast::DUMMY_NODE_ID,
+                };
+                return Ok(respan(lo.to(self.prev_span), vis));
+            } else if !can_take_tuple { // Provide this diagnostic if this is not a tuple struct.
+                self.recover_incorrect_vis_restriction()?;
+                // Emit diagnostic, but continue with public visibility.
+            }
+        }
+
+        Ok(respan(lo, VisibilityKind::Public))
+    }
+
+    /// Recovery for e.g. `pub(something) fn ...` or `struct X { pub(something) y: Z }`
+    fn recover_incorrect_vis_restriction(&mut self) -> PResult<'a, ()> {
+        self.bump(); // `(`
+        let path = self.parse_path(PathStyle::Mod)?;
+        self.expect(&token::CloseDelim(token::Paren))?;  // `)`
+
+        let msg = "incorrect visibility restriction";
+        let suggestion = r##"some possible visibility restrictions are:
+`pub(crate)`: visible only on the current crate
+`pub(super)`: visible only in the current module's parent
+`pub(in path::to::module)`: visible only on the specified path"##;
+
+        let path_str = pprust::path_to_string(&path);
+
+        struct_span_err!(self.sess.span_diagnostic, path.span, E0704, "{}", msg)
+            .help(suggestion)
+            .span_suggestion(
+                path.span,
+                &format!("make this visible only to module `{}` with `in`", path_str),
+                format!("in {}", path_str),
+                Applicability::MachineApplicable,
+            )
+            .emit();
+
+        Ok(())
+    }
+
+    /// Parses `extern string_literal?`.
+    /// If `extern` is not found, the Rust ABI is used.
+    /// If `extern` is found and a `string_literal` does not follow, the C ABI is used.
+    fn parse_extern_abi(&mut self) -> PResult<'a, Abi> {
+        Ok(if self.eat_keyword(kw::Extern) {
+            self.parse_opt_abi()?
+        } else {
+            Abi::default()
+        })
+    }
+
+    /// Parses a string literal as an ABI spec.
+    /// If one is not found, the "C" ABI is used.
+    fn parse_opt_abi(&mut self) -> PResult<'a, Abi> {
+        let span = if self.token.can_begin_literal_or_bool() {
+            let ast::Lit { span, kind, .. } = self.parse_lit()?;
+            match kind {
+                ast::LitKind::Str(symbol, _) => return Ok(Abi::new(symbol, span)),
+                ast::LitKind::Err(_) => {}
+                _ => {
+                    self.struct_span_err(span, "non-string ABI literal")
+                        .span_suggestion(
+                            span,
+                            "specify the ABI with a string literal",
+                            "\"C\"".to_string(),
+                            Applicability::MaybeIncorrect,
+                        )
+                        .emit();
+                }
+            }
+            span
+        } else {
+            self.prev_span
+        };
+        Ok(Abi::new(sym::C, span))
+    }
+
+    /// We are parsing `async fn`. If we are on Rust 2015, emit an error.
+    fn ban_async_in_2015(&self, async_span: Span) {
+        if async_span.rust_2015() {
+            self.diagnostic()
+                .struct_span_err_with_code(
+                    async_span,
+                    "`async fn` is not permitted in the 2015 edition",
+                    DiagnosticId::Error("E0670".into())
+                )
+                .emit();
+        }
+    }
+
+    fn collect_tokens<R>(
+        &mut self,
+        f: impl FnOnce(&mut Self) -> PResult<'a, R>,
+    ) -> PResult<'a, (R, TokenStream)> {
+        // Record all tokens we parse when parsing this item.
+        let mut tokens = Vec::new();
+        let prev_collecting = match self.token_cursor.frame.last_token {
+            LastToken::Collecting(ref mut list) => {
+                Some(mem::take(list))
+            }
+            LastToken::Was(ref mut last) => {
+                tokens.extend(last.take());
+                None
+            }
+        };
+        self.token_cursor.frame.last_token = LastToken::Collecting(tokens);
+        let prev = self.token_cursor.stack.len();
+        let ret = f(self);
+        let last_token = if self.token_cursor.stack.len() == prev {
+            &mut self.token_cursor.frame.last_token
+        } else if self.token_cursor.stack.get(prev).is_none() {
+            // This can happen due to a bad interaction of two unrelated recovery mechanisms with
+            // mismatched delimiters *and* recovery lookahead on the likely typo `pub ident(`
+            // (#62881).
+            return Ok((ret?, TokenStream::default()));
+        } else {
+            &mut self.token_cursor.stack[prev].last_token
+        };
+
+        // Pull out the tokens that we've collected from the call to `f` above.
+        let mut collected_tokens = match *last_token {
+            LastToken::Collecting(ref mut v) => mem::take(v),
+            LastToken::Was(ref was) => {
+                let msg = format!("our vector went away? - found Was({:?})", was);
+                debug!("collect_tokens: {}", msg);
+                self.sess.span_diagnostic.delay_span_bug(self.token.span, &msg);
+                // This can happen due to a bad interaction of two unrelated recovery mechanisms
+                // with mismatched delimiters *and* recovery lookahead on the likely typo
+                // `pub ident(` (#62895, different but similar to the case above).
+                return Ok((ret?, TokenStream::default()));
+            }
+        };
+
+        // If we're not at EOF our current token wasn't actually consumed by
+        // `f`, but it'll still be in our list that we pulled out. In that case
+        // put it back.
+        let extra_token = if self.token != token::Eof {
+            collected_tokens.pop()
+        } else {
+            None
+        };
+
+        // If we were previously collecting tokens, then this was a recursive
+        // call. In that case we need to record all the tokens we collected in
+        // our parent list as well. To do that we push a clone of our stream
+        // onto the previous list.
+        match prev_collecting {
+            Some(mut list) => {
+                list.extend(collected_tokens.iter().cloned());
+                list.extend(extra_token);
+                *last_token = LastToken::Collecting(list);
+            }
+            None => {
+                *last_token = LastToken::Was(extra_token);
+            }
+        }
+
+        Ok((ret?, TokenStream::new(collected_tokens)))
+    }
+
+    /// `::{` or `::*`
+    fn is_import_coupler(&mut self) -> bool {
+        self.check(&token::ModSep) &&
+            self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace) ||
+                                   *t == token::BinOp(token::Star))
+    }
+
+    fn parse_optional_str(&mut self) -> Option<(Symbol, ast::StrStyle, Option<ast::Name>)> {
+        let ret = match self.token.kind {
+            token::Literal(token::Lit { kind: token::Str, symbol, suffix }) =>
+                (symbol, ast::StrStyle::Cooked, suffix),
+            token::Literal(token::Lit { kind: token::StrRaw(n), symbol, suffix }) =>
+                (symbol, ast::StrStyle::Raw(n), suffix),
+            _ => return None
+        };
+        self.bump();
+        Some(ret)
+    }
+
+    pub fn parse_str(&mut self) -> PResult<'a, (Symbol, StrStyle)> {
+        match self.parse_optional_str() {
+            Some((s, style, suf)) => {
+                let sp = self.prev_span;
+                self.expect_no_suffix(sp, "a string literal", suf);
+                Ok((s, style))
+            }
+            _ => {
+                let msg = "expected string literal";
+                let mut err = self.fatal(msg);
+                err.span_label(self.token.span, msg);
+                Err(err)
+            }
+        }
+    }
+}
+
+crate fn make_unclosed_delims_error(
+    unmatched: UnmatchedBrace,
+    sess: &ParseSess,
+) -> Option<DiagnosticBuilder<'_>> {
+    // `None` here means an `Eof` was found. We already emit those errors elsewhere, we add them to
+    // `unmatched_braces` only for error recovery in the `Parser`.
+    let found_delim = unmatched.found_delim?;
+    let mut err = sess.span_diagnostic.struct_span_err(unmatched.found_span, &format!(
+        "incorrect close delimiter: `{}`",
+        pprust::token_kind_to_string(&token::CloseDelim(found_delim)),
+    ));
+    err.span_label(unmatched.found_span, "incorrect close delimiter");
+    if let Some(sp) = unmatched.candidate_span {
+        err.span_label(sp, "close delimiter possibly meant for this");
+    }
+    if let Some(sp) = unmatched.unclosed_span {
+        err.span_label(sp, "un-closed delimiter");
+    }
+    Some(err)
+}
+
+pub fn emit_unclosed_delims(unclosed_delims: &mut Vec<UnmatchedBrace>, sess: &ParseSess) {
+    *sess.reached_eof.borrow_mut() |= unclosed_delims.iter()
+        .any(|unmatched_delim| unmatched_delim.found_delim.is_none());
+    for unmatched in unclosed_delims.drain(..) {
+        make_unclosed_delims_error(unmatched, sess).map(|mut e| e.emit());
+    }
+}
diff --git a/src/librustc_parse/parser/module.rs b/src/librustc_parse/parser/module.rs
new file mode 100644
index 00000000000..3110f15e80b
--- /dev/null
+++ b/src/librustc_parse/parser/module.rs
@@ -0,0 +1,316 @@
+use super::Parser;
+use super::item::ItemInfo;
+use super::diagnostics::Error;
+
+use crate::{new_sub_parser_from_file, DirectoryOwnership};
+
+use syntax::attr;
+use syntax::ast::{self, Ident, Attribute, ItemKind, Mod, Crate};
+use syntax::token::{self, TokenKind};
+use syntax::source_map::{SourceMap, Span, DUMMY_SP, FileName};
+
+use syntax_pos::symbol::sym;
+use errors::PResult;
+
+use std::path::{self, Path, PathBuf};
+
+/// Information about the path to a module.
+pub(super) struct ModulePath {
+    name: String,
+    path_exists: bool,
+    pub result: Result<ModulePathSuccess, Error>,
+}
+
+pub(super) struct ModulePathSuccess {
+    pub path: PathBuf,
+    pub directory_ownership: DirectoryOwnership,
+}
+
+impl<'a> Parser<'a> {
+    /// Parses a source module as a crate. This is the main entry point for the parser.
+    pub fn parse_crate_mod(&mut self) -> PResult<'a, Crate> {
+        let lo = self.token.span;
+        let krate = Ok(ast::Crate {
+            attrs: self.parse_inner_attributes()?,
+            module: self.parse_mod_items(&token::Eof, lo)?,
+            span: lo.to(self.token.span),
+        });
+        krate
+    }
+
+    /// Parses a `mod <foo> { ... }` or `mod <foo>;` item.
+    pub(super) fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
+        // HACK(Centril): See documentation on `ParseSess::process_cfg_mod`.
+        let (in_cfg, outer_attrs) = (self.sess.process_cfg_mod)(
+            self.sess,
+            self.cfg_mods,
+            outer_attrs,
+        );
+
+        let id_span = self.token.span;
+        let id = self.parse_ident()?;
+        if self.eat(&token::Semi) {
+            if in_cfg && self.recurse_into_file_modules {
+                // This mod is in an external file. Let's go get it!
+                let ModulePathSuccess { path, directory_ownership } =
+                    self.submod_path(id, &outer_attrs, id_span)?;
+                let (module, attrs) =
+                    self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?;
+                Ok((id, ItemKind::Mod(module), Some(attrs)))
+            } else {
+                let placeholder = ast::Mod {
+                    inner: DUMMY_SP,
+                    items: Vec::new(),
+                    inline: false
+                };
+                Ok((id, ItemKind::Mod(placeholder), None))
+            }
+        } else {
+            let old_directory = self.directory.clone();
+            self.push_directory(id, &outer_attrs);
+
+            self.expect(&token::OpenDelim(token::Brace))?;
+            let mod_inner_lo = self.token.span;
+            let attrs = self.parse_inner_attributes()?;
+            let module = self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo)?;
+
+            self.directory = old_directory;
+            Ok((id, ItemKind::Mod(module), Some(attrs)))
+        }
+    }
+
+    /// Given a termination token, parses all of the items in a module.
+    fn parse_mod_items(&mut self, term: &TokenKind, inner_lo: Span) -> PResult<'a, Mod> {
+        let mut items = vec![];
+        while let Some(item) = self.parse_item()? {
+            items.push(item);
+            self.maybe_consume_incorrect_semicolon(&items);
+        }
+
+        if !self.eat(term) {
+            let token_str = self.this_token_descr();
+            if !self.maybe_consume_incorrect_semicolon(&items) {
+                let mut err = self.fatal(&format!("expected item, found {}", token_str));
+                err.span_label(self.token.span, "expected item");
+                return Err(err);
+            }
+        }
+
+        let hi = if self.token.span.is_dummy() {
+            inner_lo
+        } else {
+            self.prev_span
+        };
+
+        Ok(Mod {
+            inner: inner_lo.to(hi),
+            items,
+            inline: true
+        })
+    }
+
+    fn submod_path(
+        &mut self,
+        id: ast::Ident,
+        outer_attrs: &[Attribute],
+        id_sp: Span
+    ) -> PResult<'a, ModulePathSuccess> {
+        if let Some(path) = Parser::submod_path_from_attr(outer_attrs, &self.directory.path) {
+            return Ok(ModulePathSuccess {
+                directory_ownership: match path.file_name().and_then(|s| s.to_str()) {
+                    // All `#[path]` files are treated as though they are a `mod.rs` file.
+                    // This means that `mod foo;` declarations inside `#[path]`-included
+                    // files are siblings,
+                    //
+                    // Note that this will produce weirdness when a file named `foo.rs` is
+                    // `#[path]` included and contains a `mod foo;` declaration.
+                    // If you encounter this, it's your own darn fault :P
+                    Some(_) => DirectoryOwnership::Owned { relative: None },
+                    _ => DirectoryOwnership::UnownedViaMod,
+                },
+                path,
+            });
+        }
+
+        let relative = match self.directory.ownership {
+            DirectoryOwnership::Owned { relative } => relative,
+            DirectoryOwnership::UnownedViaBlock |
+            DirectoryOwnership::UnownedViaMod => None,
+        };
+        let paths = Parser::default_submod_path(
+                        id, relative, &self.directory.path, self.sess.source_map());
+
+        match self.directory.ownership {
+            DirectoryOwnership::Owned { .. } => {
+                paths.result.map_err(|err| self.span_fatal_err(id_sp, err))
+            },
+            DirectoryOwnership::UnownedViaBlock => {
+                let msg =
+                    "Cannot declare a non-inline module inside a block \
+                    unless it has a path attribute";
+                let mut err = self.diagnostic().struct_span_err(id_sp, msg);
+                if paths.path_exists {
+                    let msg = format!("Maybe `use` the module `{}` instead of redeclaring it",
+                                      paths.name);
+                    err.span_note(id_sp, &msg);
+                }
+                Err(err)
+            }
+            DirectoryOwnership::UnownedViaMod => {
+                let mut err = self.diagnostic().struct_span_err(id_sp,
+                    "cannot declare a new module at this location");
+                if !id_sp.is_dummy() {
+                    let src_path = self.sess.source_map().span_to_filename(id_sp);
+                    if let FileName::Real(src_path) = src_path {
+                        if let Some(stem) = src_path.file_stem() {
+                            let mut dest_path = src_path.clone();
+                            dest_path.set_file_name(stem);
+                            dest_path.push("mod.rs");
+                            err.span_note(id_sp,
+                                    &format!("maybe move this module `{}` to its own \
+                                                directory via `{}`", src_path.display(),
+                                            dest_path.display()));
+                        }
+                    }
+                }
+                if paths.path_exists {
+                    err.span_note(id_sp,
+                                  &format!("... or maybe `use` the module `{}` instead \
+                                            of possibly redeclaring it",
+                                           paths.name));
+                }
+                Err(err)
+            }
+        }
+    }
+
+    pub(super) fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> {
+        if let Some(s) = attr::first_attr_value_str_by_name(attrs, sym::path) {
+            let s = s.as_str();
+
+            // On windows, the base path might have the form
+            // `\\?\foo\bar` in which case it does not tolerate
+            // mixed `/` and `\` separators, so canonicalize
+            // `/` to `\`.
+            #[cfg(windows)]
+            let s = s.replace("/", "\\");
+            Some(dir_path.join(&*s))
+        } else {
+            None
+        }
+    }
+
+    /// Returns a path to a module.
+    pub(super) fn default_submod_path(
+        id: ast::Ident,
+        relative: Option<ast::Ident>,
+        dir_path: &Path,
+        source_map: &SourceMap) -> ModulePath
+    {
+        // If we're in a foo.rs file instead of a mod.rs file,
+        // we need to look for submodules in
+        // `./foo/<id>.rs` and `./foo/<id>/mod.rs` rather than
+        // `./<id>.rs` and `./<id>/mod.rs`.
+        let relative_prefix_string;
+        let relative_prefix = if let Some(ident) = relative {
+            relative_prefix_string = format!("{}{}", ident, path::MAIN_SEPARATOR);
+            &relative_prefix_string
+        } else {
+            ""
+        };
+
+        let mod_name = id.to_string();
+        let default_path_str = format!("{}{}.rs", relative_prefix, mod_name);
+        let secondary_path_str = format!("{}{}{}mod.rs",
+                                         relative_prefix, mod_name, path::MAIN_SEPARATOR);
+        let default_path = dir_path.join(&default_path_str);
+        let secondary_path = dir_path.join(&secondary_path_str);
+        let default_exists = source_map.file_exists(&default_path);
+        let secondary_exists = source_map.file_exists(&secondary_path);
+
+        let result = match (default_exists, secondary_exists) {
+            (true, false) => Ok(ModulePathSuccess {
+                path: default_path,
+                directory_ownership: DirectoryOwnership::Owned {
+                    relative: Some(id),
+                },
+            }),
+            (false, true) => Ok(ModulePathSuccess {
+                path: secondary_path,
+                directory_ownership: DirectoryOwnership::Owned {
+                    relative: None,
+                },
+            }),
+            (false, false) => Err(Error::FileNotFoundForModule {
+                mod_name: mod_name.clone(),
+                default_path: default_path_str,
+                secondary_path: secondary_path_str,
+                dir_path: dir_path.display().to_string(),
+            }),
+            (true, true) => Err(Error::DuplicatePaths {
+                mod_name: mod_name.clone(),
+                default_path: default_path_str,
+                secondary_path: secondary_path_str,
+            }),
+        };
+
+        ModulePath {
+            name: mod_name,
+            path_exists: default_exists || secondary_exists,
+            result,
+        }
+    }
+
+    /// Reads a module from a source file.
+    fn eval_src_mod(
+        &mut self,
+        path: PathBuf,
+        directory_ownership: DirectoryOwnership,
+        name: String,
+        id_sp: Span,
+    ) -> PResult<'a, (Mod, Vec<Attribute>)> {
+        let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
+        if let Some(i) = included_mod_stack.iter().position(|p| *p == path) {
+            let mut err = String::from("circular modules: ");
+            let len = included_mod_stack.len();
+            for p in &included_mod_stack[i.. len] {
+                err.push_str(&p.to_string_lossy());
+                err.push_str(" -> ");
+            }
+            err.push_str(&path.to_string_lossy());
+            return Err(self.span_fatal(id_sp, &err[..]));
+        }
+        included_mod_stack.push(path.clone());
+        drop(included_mod_stack);
+
+        let mut p0 =
+            new_sub_parser_from_file(self.sess, &path, directory_ownership, Some(name), id_sp);
+        p0.cfg_mods = self.cfg_mods;
+        let mod_inner_lo = p0.token.span;
+        let mod_attrs = p0.parse_inner_attributes()?;
+        let mut m0 = p0.parse_mod_items(&token::Eof, mod_inner_lo)?;
+        m0.inline = false;
+        self.sess.included_mod_stack.borrow_mut().pop();
+        Ok((m0, mod_attrs))
+    }
+
+    fn push_directory(&mut self, id: Ident, attrs: &[Attribute]) {
+        if let Some(path) = attr::first_attr_value_str_by_name(attrs, sym::path) {
+            self.directory.path.to_mut().push(&*path.as_str());
+            self.directory.ownership = DirectoryOwnership::Owned { relative: None };
+        } else {
+            // We have to push on the current module name in the case of relative
+            // paths in order to ensure that any additional module paths from inline
+            // `mod x { ... }` come after the relative extension.
+            //
+            // For example, a `mod z { ... }` inside `x/y.rs` should set the current
+            // directory path to `/x/y/z`, not `/x/z` with a relative offset of `y`.
+            if let DirectoryOwnership::Owned { relative } = &mut self.directory.ownership {
+                if let Some(ident) = relative.take() { // remove the relative offset
+                    self.directory.path.to_mut().push(&*ident.as_str());
+                }
+            }
+            self.directory.path.to_mut().push(&*id.as_str());
+        }
+    }
+}
diff --git a/src/librustc_parse/parser/pat.rs b/src/librustc_parse/parser/pat.rs
new file mode 100644
index 00000000000..b068a4f16a5
--- /dev/null
+++ b/src/librustc_parse/parser/pat.rs
@@ -0,0 +1,1015 @@
+use super::{Parser, PathStyle};
+use crate::{maybe_recover_from_interpolated_ty_qpath, maybe_whole};
+use syntax::ast::{self, Attribute, Pat, PatKind, FieldPat, RangeEnd, RangeSyntax, Mac};
+use syntax::ast::{BindingMode, Ident, Mutability, Path, QSelf, Expr, ExprKind};
+use syntax::mut_visit::{noop_visit_pat, noop_visit_mac, MutVisitor};
+use syntax::ptr::P;
+use syntax::print::pprust;
+use syntax::ThinVec;
+use syntax::token;
+use syntax::source_map::{respan, Span, Spanned};
+use syntax_pos::symbol::{kw, sym};
+use errors::{PResult, Applicability, DiagnosticBuilder};
+
+type Expected = Option<&'static str>;
+
+/// `Expected` for function and lambda parameter patterns.
+pub(super) const PARAM_EXPECTED: Expected = Some("parameter name");
+
+const WHILE_PARSING_OR_MSG: &str = "while parsing this or-pattern starting here";
+
+/// Whether or not an or-pattern should be gated when occurring in the current context.
+#[derive(PartialEq)]
+pub(super) enum GateOr { Yes, No }
+
+/// Whether or not to recover a `,` when parsing or-patterns.
+#[derive(PartialEq, Copy, Clone)]
+enum RecoverComma { Yes, No }
+
+impl<'a> Parser<'a> {
+    /// Parses a pattern.
+    ///
+    /// Corresponds to `pat<no_top_alt>` in RFC 2535 and does not admit or-patterns
+    /// at the top level. Used when parsing the parameters of lambda expressions,
+    /// functions, function pointers, and `pat` macro fragments.
+    pub fn parse_pat(&mut self, expected: Expected) -> PResult<'a, P<Pat>> {
+        self.parse_pat_with_range_pat(true, expected)
+    }
+
+    /// Entry point to the main pattern parser.
+    /// Corresponds to `top_pat` in RFC 2535 and allows or-pattern at the top level.
+    pub(super) fn parse_top_pat(&mut self, gate_or: GateOr) -> PResult<'a, P<Pat>> {
+        // Allow a '|' before the pats (RFCs 1925, 2530, and 2535).
+        let gated_leading_vert = self.eat_or_separator(None) && gate_or == GateOr::Yes;
+        let leading_vert_span = self.prev_span;
+
+        // Parse the possibly-or-pattern.
+        let pat = self.parse_pat_with_or(None, gate_or, RecoverComma::Yes)?;
+
+        // If we parsed a leading `|` which should be gated,
+        // and no other gated or-pattern has been parsed thus far,
+        // then we should really gate the leading `|`.
+        // This complicated procedure is done purely for diagnostics UX.
+        if gated_leading_vert && self.sess.gated_spans.is_ungated(sym::or_patterns) {
+            self.sess.gated_spans.gate(sym::or_patterns, leading_vert_span);
+        }
+
+        Ok(pat)
+    }
+
+    /// Parse the pattern for a function or function pointer parameter.
+    /// Special recovery is provided for or-patterns and leading `|`.
+    pub(super) fn parse_fn_param_pat(&mut self) -> PResult<'a, P<Pat>> {
+        self.recover_leading_vert(None, "not allowed in a parameter pattern");
+        let pat = self.parse_pat_with_or(PARAM_EXPECTED, GateOr::No, RecoverComma::No)?;
+
+        if let PatKind::Or(..) = &pat.kind {
+            self.ban_illegal_fn_param_or_pat(&pat);
+        }
+
+        Ok(pat)
+    }
+
+    /// Ban `A | B` immediately in a parameter pattern and suggest wrapping in parens.
+    fn ban_illegal_fn_param_or_pat(&self, pat: &Pat) {
+        let msg = "wrap the pattern in parenthesis";
+        let fix = format!("({})", pprust::pat_to_string(pat));
+        self.struct_span_err(pat.span, "an or-pattern parameter must be wrapped in parenthesis")
+            .span_suggestion(pat.span, msg, fix, Applicability::MachineApplicable)
+            .emit();
+    }
+
+    /// Parses a pattern, that may be a or-pattern (e.g. `Foo | Bar` in `Some(Foo | Bar)`).
+    /// Corresponds to `pat<allow_top_alt>` in RFC 2535.
+    fn parse_pat_with_or(
+        &mut self,
+        expected: Expected,
+        gate_or: GateOr,
+        rc: RecoverComma,
+    ) -> PResult<'a, P<Pat>> {
+        // Parse the first pattern (`p_0`).
+        let first_pat = self.parse_pat(expected)?;
+        self.maybe_recover_unexpected_comma(first_pat.span, rc)?;
+
+        // If the next token is not a `|`,
+        // this is not an or-pattern and we should exit here.
+        if !self.check(&token::BinOp(token::Or)) && self.token != token::OrOr {
+            return Ok(first_pat)
+        }
+
+        // Parse the patterns `p_1 | ... | p_n` where `n > 0`.
+        let lo = first_pat.span;
+        let mut pats = vec![first_pat];
+        while self.eat_or_separator(Some(lo)) {
+            let pat = self.parse_pat(expected).map_err(|mut err| {
+                err.span_label(lo, WHILE_PARSING_OR_MSG);
+                err
+            })?;
+            self.maybe_recover_unexpected_comma(pat.span, rc)?;
+            pats.push(pat);
+        }
+        let or_pattern_span = lo.to(self.prev_span);
+
+        // Feature gate the or-pattern if instructed:
+        if gate_or == GateOr::Yes {
+            self.sess.gated_spans.gate(sym::or_patterns, or_pattern_span);
+        }
+
+        Ok(self.mk_pat(or_pattern_span, PatKind::Or(pats)))
+    }
+
+    /// Eat the or-pattern `|` separator.
+    /// If instead a `||` token is encountered, recover and pretend we parsed `|`.
+    fn eat_or_separator(&mut self, lo: Option<Span>) -> bool {
+        if self.recover_trailing_vert(lo) {
+            return false;
+        }
+
+        match self.token.kind {
+            token::OrOr => {
+                // Found `||`; Recover and pretend we parsed `|`.
+                self.ban_unexpected_or_or(lo);
+                self.bump();
+                true
+            }
+            _ => self.eat(&token::BinOp(token::Or)),
+        }
+    }
+
+    /// Recover if `|` or `||` is the current token and we have one of the
+    /// tokens `=>`, `if`, `=`, `:`, `;`, `,`, `]`, `)`, or `}` ahead of us.
+    ///
+    /// These tokens all indicate that we reached the end of the or-pattern
+    /// list and can now reliably say that the `|` was an illegal trailing vert.
+    /// Note that there are more tokens such as `@` for which we know that the `|`
+    /// is an illegal parse. However, the user's intent is less clear in that case.
+    fn recover_trailing_vert(&mut self, lo: Option<Span>) -> bool {
+        let is_end_ahead = self.look_ahead(1, |token| match &token.kind {
+            token::FatArrow // e.g. `a | => 0,`.
+            | token::Ident(kw::If, false) // e.g. `a | if expr`.
+            | token::Eq // e.g. `let a | = 0`.
+            | token::Semi // e.g. `let a |;`.
+            | token::Colon // e.g. `let a | :`.
+            | token::Comma // e.g. `let (a |,)`.
+            | token::CloseDelim(token::Bracket) // e.g. `let [a | ]`.
+            | token::CloseDelim(token::Paren) // e.g. `let (a | )`.
+            | token::CloseDelim(token::Brace) => true, // e.g. `let A { f: a | }`.
+            _ => false,
+        });
+        match (is_end_ahead, &self.token.kind) {
+            (true, token::BinOp(token::Or)) | (true, token::OrOr) => {
+                self.ban_illegal_vert(lo, "trailing", "not allowed in an or-pattern");
+                self.bump();
+                true
+            }
+            _ => false,
+        }
+    }
+
+    /// We have parsed `||` instead of `|`. Error and suggest `|` instead.
+    fn ban_unexpected_or_or(&mut self, lo: Option<Span>) {
+        let mut err = self.struct_span_err(self.token.span, "unexpected token `||` after pattern");
+        err.span_suggestion(
+            self.token.span,
+            "use a single `|` to separate multiple alternative patterns",
+            "|".to_owned(),
+            Applicability::MachineApplicable
+        );
+        if let Some(lo) = lo {
+            err.span_label(lo, WHILE_PARSING_OR_MSG);
+        }
+        err.emit();
+    }
+
+    /// Some special error handling for the "top-level" patterns in a match arm,
+    /// `for` loop, `let`, &c. (in contrast to subpatterns within such).
+    fn maybe_recover_unexpected_comma(&mut self, lo: Span, rc: RecoverComma) -> PResult<'a, ()> {
+        if rc == RecoverComma::No || self.token != token::Comma {
+            return Ok(());
+        }
+
+        // An unexpected comma after a top-level pattern is a clue that the
+        // user (perhaps more accustomed to some other language) forgot the
+        // parentheses in what should have been a tuple pattern; return a
+        // suggestion-enhanced error here rather than choking on the comma later.
+        let comma_span = self.token.span;
+        self.bump();
+        if let Err(mut err) = self.skip_pat_list() {
+            // We didn't expect this to work anyway; we just wanted to advance to the
+            // end of the comma-sequence so we know the span to suggest parenthesizing.
+            err.cancel();
+        }
+        let seq_span = lo.to(self.prev_span);
+        let mut err = self.struct_span_err(comma_span, "unexpected `,` in pattern");
+        if let Ok(seq_snippet) = self.span_to_snippet(seq_span) {
+            err.span_suggestion(
+                seq_span,
+                "try adding parentheses to match on a tuple..",
+                format!("({})", seq_snippet),
+                Applicability::MachineApplicable
+            )
+            .span_suggestion(
+                seq_span,
+                "..or a vertical bar to match on multiple alternatives",
+                format!("{}", seq_snippet.replace(",", " |")),
+                Applicability::MachineApplicable
+            );
+        }
+        Err(err)
+    }
+
+    /// Parse and throw away a parentesized comma separated
+    /// sequence of patterns until `)` is reached.
+    fn skip_pat_list(&mut self) -> PResult<'a, ()> {
+        while !self.check(&token::CloseDelim(token::Paren)) {
+            self.parse_pat(None)?;
+            if !self.eat(&token::Comma) {
+                return Ok(())
+            }
+        }
+        Ok(())
+    }
+
+    /// Recursive possibly-or-pattern parser with recovery for an erroneous leading `|`.
+    /// See `parse_pat_with_or` for details on parsing or-patterns.
+    fn parse_pat_with_or_inner(&mut self) -> PResult<'a, P<Pat>> {
+        self.recover_leading_vert(None, "only allowed in a top-level pattern");
+        self.parse_pat_with_or(None, GateOr::Yes, RecoverComma::No)
+    }
+
+    /// Recover if `|` or `||` is here.
+    /// The user is thinking that a leading `|` is allowed in this position.
+    fn recover_leading_vert(&mut self, lo: Option<Span>, ctx: &str) {
+        if let token::BinOp(token::Or) | token::OrOr = self.token.kind {
+            self.ban_illegal_vert(lo, "leading", ctx);
+            self.bump();
+        }
+    }
+
+    /// A `|` or possibly `||` token shouldn't be here. Ban it.
+    fn ban_illegal_vert(&mut self, lo: Option<Span>, pos: &str, ctx: &str) {
+        let span = self.token.span;
+        let mut err = self.struct_span_err(span, &format!("a {} `|` is {}", pos, ctx));
+        err.span_suggestion(
+            span,
+            &format!("remove the `{}`", pprust::token_to_string(&self.token)),
+            String::new(),
+            Applicability::MachineApplicable,
+        );
+        if let Some(lo) = lo {
+            err.span_label(lo, WHILE_PARSING_OR_MSG);
+        }
+        if let token::OrOr = self.token.kind {
+            err.note("alternatives in or-patterns are separated with `|`, not `||`");
+        }
+        err.emit();
+    }
+
+    /// Parses a pattern, with a setting whether modern range patterns (e.g., `a..=b`, `a..b` are
+    /// allowed).
+    fn parse_pat_with_range_pat(
+        &mut self,
+        allow_range_pat: bool,
+        expected: Expected,
+    ) -> PResult<'a, P<Pat>> {
+        maybe_recover_from_interpolated_ty_qpath!(self, true);
+        maybe_whole!(self, NtPat, |x| x);
+
+        let lo = self.token.span;
+        let pat = match self.token.kind {
+            token::BinOp(token::And) | token::AndAnd => self.parse_pat_deref(expected)?,
+            token::OpenDelim(token::Paren) => self.parse_pat_tuple_or_parens()?,
+            token::OpenDelim(token::Bracket) => {
+                // Parse `[pat, pat,...]` as a slice pattern.
+                let (pats, _) = self.parse_delim_comma_seq(
+                    token::Bracket,
+                    |p| p.parse_pat_with_or_inner(),
+                )?;
+                PatKind::Slice(pats)
+            }
+            token::DotDot => {
+                self.bump();
+                if self.is_pat_range_end_start() {
+                    // Parse `..42` for recovery.
+                    self.parse_pat_range_to(RangeEnd::Excluded, "..")?
+                } else {
+                    // A rest pattern `..`.
+                    PatKind::Rest
+                }
+            }
+            token::DotDotEq => {
+                // Parse `..=42` for recovery.
+                self.bump();
+                self.parse_pat_range_to(RangeEnd::Included(RangeSyntax::DotDotEq), "..=")?
+            }
+            token::DotDotDot => {
+                // Parse `...42` for recovery.
+                self.bump();
+                self.parse_pat_range_to(RangeEnd::Included(RangeSyntax::DotDotDot), "...")?
+            }
+            // At this point, token != `&`, `&&`, `(`, `[`, `..`, `..=`, or `...`.
+            _ => if self.eat_keyword(kw::Underscore) {
+                // Parse _
+                PatKind::Wild
+            } else if self.eat_keyword(kw::Mut) {
+                self.parse_pat_ident_mut()?
+            } else if self.eat_keyword(kw::Ref) {
+                // Parse ref ident @ pat / ref mut ident @ pat
+                let mutbl = self.parse_mutability();
+                self.parse_pat_ident(BindingMode::ByRef(mutbl))?
+            } else if self.eat_keyword(kw::Box) {
+                // Parse `box pat`
+                let pat = self.parse_pat_with_range_pat(false, None)?;
+                self.sess.gated_spans.gate(sym::box_patterns, lo.to(self.prev_span));
+                PatKind::Box(pat)
+            } else if self.can_be_ident_pat() {
+                // Parse `ident @ pat`
+                // This can give false positives and parse nullary enums,
+                // they are dealt with later in resolve.
+                self.parse_pat_ident(BindingMode::ByValue(Mutability::Immutable))?
+            } else if self.is_start_of_pat_with_path() {
+                // Parse pattern starting with a path
+                let (qself, path) = if self.eat_lt() {
+                    // Parse a qualified path
+                    let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
+                    (Some(qself), path)
+                } else {
+                    // Parse an unqualified path
+                    (None, self.parse_path(PathStyle::Expr)?)
+                };
+                match self.token.kind {
+                    token::Not if qself.is_none() => self.parse_pat_mac_invoc(lo, path)?,
+                    token::DotDotDot | token::DotDotEq | token::DotDot => {
+                        self.parse_pat_range_starting_with_path(lo, qself, path)?
+                    }
+                    token::OpenDelim(token::Brace) => self.parse_pat_struct(qself, path)?,
+                    token::OpenDelim(token::Paren) => self.parse_pat_tuple_struct(qself, path)?,
+                    _ => PatKind::Path(qself, path),
+                }
+            } else {
+                // Try to parse everything else as literal with optional minus
+                match self.parse_literal_maybe_minus() {
+                    Ok(begin)
+                        if self.check(&token::DotDot)
+                            || self.check(&token::DotDotEq)
+                            || self.check(&token::DotDotDot) =>
+                    {
+                        self.parse_pat_range_starting_with_lit(begin)?
+                    }
+                    Ok(begin) => PatKind::Lit(begin),
+                    Err(err) => return self.fatal_unexpected_non_pat(err, expected),
+                }
+            }
+        };
+
+        let pat = self.mk_pat(lo.to(self.prev_span), pat);
+        let pat = self.maybe_recover_from_bad_qpath(pat, true)?;
+        let pat = self.recover_intersection_pat(pat)?;
+
+        if !allow_range_pat {
+            self.ban_pat_range_if_ambiguous(&pat)?
+        }
+
+        Ok(pat)
+    }
+
+    /// Try to recover the more general form `intersect ::= $pat_lhs @ $pat_rhs`.
+    ///
+    /// Allowed binding patterns generated by `binding ::= ref? mut? $ident @ $pat_rhs`
+    /// should already have been parsed by now  at this point,
+    /// if the next token is `@` then we can try to parse the more general form.
+    ///
+    /// Consult `parse_pat_ident` for the `binding` grammar.
+    ///
+    /// The notion of intersection patterns are found in
+    /// e.g. [F#][and] where they are called AND-patterns.
+    ///
+    /// [and]: https://docs.microsoft.com/en-us/dotnet/fsharp/language-reference/pattern-matching
+    fn recover_intersection_pat(&mut self, lhs: P<Pat>) -> PResult<'a, P<Pat>> {
+        if self.token.kind != token::At {
+            // Next token is not `@` so it's not going to be an intersection pattern.
+            return Ok(lhs);
+        }
+
+        // At this point we attempt to parse `@ $pat_rhs` and emit an error.
+        self.bump(); // `@`
+        let mut rhs = self.parse_pat(None)?;
+        let sp = lhs.span.to(rhs.span);
+
+        if let PatKind::Ident(_, _, ref mut sub @ None) = rhs.kind {
+            // The user inverted the order, so help them fix that.
+            let mut applicability = Applicability::MachineApplicable;
+            lhs.walk(&mut |p| match p.kind {
+                // `check_match` is unhappy if the subpattern has a binding anywhere.
+                PatKind::Ident(..) => {
+                    applicability = Applicability::MaybeIncorrect;
+                    false // Short-circuit.
+                },
+                _ => true,
+            });
+
+            let lhs_span = lhs.span;
+            // Move the LHS into the RHS as a subpattern.
+            // The RHS is now the full pattern.
+            *sub = Some(lhs);
+
+            self.struct_span_err(sp, "pattern on wrong side of `@`")
+                .span_label(lhs_span, "pattern on the left, should be on the right")
+                .span_label(rhs.span, "binding on the right, should be on the left")
+                .span_suggestion(sp, "switch the order", pprust::pat_to_string(&rhs), applicability)
+                .emit();
+        } else {
+            // The special case above doesn't apply so we may have e.g. `A(x) @ B(y)`.
+            rhs.kind = PatKind::Wild;
+            self.struct_span_err(sp, "left-hand side of `@` must be a binding")
+                .span_label(lhs.span, "interpreted as a pattern, not a binding")
+                .span_label(rhs.span, "also a pattern")
+                .note("bindings are `x`, `mut x`, `ref x`, and `ref mut x`")
+                .emit();
+        }
+
+        rhs.span = sp;
+        Ok(rhs)
+    }
+
+    /// Ban a range pattern if it has an ambiguous interpretation.
+    fn ban_pat_range_if_ambiguous(&self, pat: &Pat) -> PResult<'a, ()> {
+        match pat.kind {
+            PatKind::Range(
+                .., Spanned { node: RangeEnd::Included(RangeSyntax::DotDotDot), .. }
+            ) => return Ok(()),
+            PatKind::Range(..) => {}
+            _ => return Ok(()),
+        }
+
+        let mut err = self.struct_span_err(
+            pat.span,
+            "the range pattern here has ambiguous interpretation",
+        );
+        err.span_suggestion(
+            pat.span,
+            "add parentheses to clarify the precedence",
+            format!("({})", pprust::pat_to_string(&pat)),
+            // "ambiguous interpretation" implies that we have to be guessing
+            Applicability::MaybeIncorrect
+        );
+        Err(err)
+    }
+
+    /// Parse `&pat` / `&mut pat`.
+    fn parse_pat_deref(&mut self, expected: Expected) -> PResult<'a, PatKind> {
+        self.expect_and()?;
+        let mutbl = self.parse_mutability();
+
+        if let token::Lifetime(name) = self.token.kind {
+            let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern", name));
+            err.span_label(self.token.span, "unexpected lifetime");
+            return Err(err);
+        }
+
+        let subpat = self.parse_pat_with_range_pat(false, expected)?;
+        Ok(PatKind::Ref(subpat, mutbl))
+    }
+
+    /// Parse a tuple or parenthesis pattern.
+    fn parse_pat_tuple_or_parens(&mut self) -> PResult<'a, PatKind> {
+        let (fields, trailing_comma) = self.parse_paren_comma_seq(|p| p.parse_pat_with_or_inner())?;
+
+        // Here, `(pat,)` is a tuple pattern.
+        // For backward compatibility, `(..)` is a tuple pattern as well.
+        Ok(if fields.len() == 1 && !(trailing_comma || fields[0].is_rest()) {
+            PatKind::Paren(fields.into_iter().nth(0).unwrap())
+        } else {
+            PatKind::Tuple(fields)
+        })
+    }
+
+    /// Parse a mutable binding with the `mut` token already eaten.
+    fn parse_pat_ident_mut(&mut self) -> PResult<'a, PatKind> {
+        let mut_span = self.prev_span;
+
+        if self.eat_keyword(kw::Ref) {
+            return self.recover_mut_ref_ident(mut_span)
+        }
+
+        self.recover_additional_muts();
+
+        // Make sure we don't allow e.g. `let mut $p;` where `$p:pat`.
+        if let token::Interpolated(ref nt) = self.token.kind {
+             if let token::NtPat(_) = **nt {
+                 self.expected_ident_found().emit();
+             }
+        }
+
+        // Parse the pattern we hope to be an identifier.
+        let mut pat = self.parse_pat(Some("identifier"))?;
+
+        // Add `mut` to any binding in the parsed pattern.
+        let changed_any_binding = Self::make_all_value_bindings_mutable(&mut pat);
+
+        // Unwrap; If we don't have `mut $ident`, error.
+        let pat = pat.into_inner();
+        match &pat.kind {
+            PatKind::Ident(..) => {}
+            _ => self.ban_mut_general_pat(mut_span, &pat, changed_any_binding),
+        }
+
+        Ok(pat.kind)
+    }
+
+    /// Recover on `mut ref? ident @ pat` and suggest
+    /// that the order of `mut` and `ref` is incorrect.
+    fn recover_mut_ref_ident(&mut self, lo: Span) -> PResult<'a, PatKind> {
+        let mutref_span = lo.to(self.prev_span);
+        self.struct_span_err(mutref_span, "the order of `mut` and `ref` is incorrect")
+            .span_suggestion(
+                mutref_span,
+                "try switching the order",
+                "ref mut".into(),
+                Applicability::MachineApplicable
+            )
+            .emit();
+
+        self.parse_pat_ident(BindingMode::ByRef(Mutability::Mutable))
+    }
+
+    /// Turn all by-value immutable bindings in a pattern into mutable bindings.
+    /// Returns `true` if any change was made.
+    fn make_all_value_bindings_mutable(pat: &mut P<Pat>) -> bool {
+        struct AddMut(bool);
+        impl MutVisitor for AddMut {
+            fn visit_mac(&mut self, mac: &mut Mac) {
+                noop_visit_mac(mac, self);
+            }
+
+            fn visit_pat(&mut self, pat: &mut P<Pat>) {
+                if let PatKind::Ident(BindingMode::ByValue(ref mut m @ Mutability::Immutable), ..)
+                    = pat.kind
+                {
+                    *m = Mutability::Mutable;
+                    self.0 = true;
+                }
+                noop_visit_pat(pat, self);
+            }
+        }
+
+        let mut add_mut = AddMut(false);
+        add_mut.visit_pat(pat);
+        add_mut.0
+    }
+
+    /// Error on `mut $pat` where `$pat` is not an ident.
+    fn ban_mut_general_pat(&self, lo: Span, pat: &Pat, changed_any_binding: bool) {
+        let span = lo.to(pat.span);
+        let fix = pprust::pat_to_string(&pat);
+        let (problem, suggestion) = if changed_any_binding {
+            ("`mut` must be attached to each individual binding", "add `mut` to each binding")
+        } else {
+            ("`mut` must be followed by a named binding", "remove the `mut` prefix")
+        };
+        self.struct_span_err(span, problem)
+            .span_suggestion(span, suggestion, fix, Applicability::MachineApplicable)
+            .note("`mut` may be followed by `variable` and `variable @ pattern`")
+            .emit()
+    }
+
+    /// Eat any extraneous `mut`s and error + recover if we ate any.
+    fn recover_additional_muts(&mut self) {
+        let lo = self.token.span;
+        while self.eat_keyword(kw::Mut) {}
+        if lo == self.token.span {
+            return;
+        }
+
+        let span = lo.to(self.prev_span);
+        self.struct_span_err(span, "`mut` on a binding may not be repeated")
+            .span_suggestion(
+                span,
+                "remove the additional `mut`s",
+                String::new(),
+                Applicability::MachineApplicable,
+            )
+            .emit();
+    }
+
+    /// Parse macro invocation
+    fn parse_pat_mac_invoc(&mut self, lo: Span, path: Path) -> PResult<'a, PatKind> {
+        self.bump();
+        let (delim, tts) = self.expect_delimited_token_tree()?;
+        let mac = Mac {
+            path,
+            tts,
+            delim,
+            span: lo.to(self.prev_span),
+            prior_type_ascription: self.last_type_ascription,
+        };
+        Ok(PatKind::Mac(mac))
+    }
+
+    fn excluded_range_end(&self, span: Span) -> RangeEnd {
+        self.sess.gated_spans.gate(sym::exclusive_range_pattern, span);
+        RangeEnd::Excluded
+    }
+
+    /// Parse a range pattern `$path $form $end?` where `$form = ".." | "..." | "..=" ;`.
+    /// The `$path` has already been parsed and the next token is the `$form`.
+    fn parse_pat_range_starting_with_path(
+        &mut self,
+        lo: Span,
+        qself: Option<QSelf>,
+        path: Path
+    ) -> PResult<'a, PatKind> {
+        let (end_kind, form) = match self.token.kind {
+            token::DotDot => (self.excluded_range_end(self.token.span), ".."),
+            token::DotDotDot => (RangeEnd::Included(RangeSyntax::DotDotDot), "..."),
+            token::DotDotEq => (RangeEnd::Included(RangeSyntax::DotDotEq), "..="),
+            _ => panic!("can only parse `..`/`...`/`..=` for ranges (checked above)"),
+        };
+        let op_span = self.token.span;
+        // Parse range
+        let span = lo.to(self.prev_span);
+        let begin = self.mk_expr(span, ExprKind::Path(qself, path), ThinVec::new());
+        self.bump();
+        let end = self.parse_pat_range_end_opt(&begin, form)?;
+        Ok(PatKind::Range(begin, end, respan(op_span, end_kind)))
+    }
+
+    /// Parse a range pattern `$literal $form $end?` where `$form = ".." | "..." | "..=" ;`.
+    /// The `$path` has already been parsed and the next token is the `$form`.
+    fn parse_pat_range_starting_with_lit(&mut self, begin: P<Expr>) -> PResult<'a, PatKind> {
+        let op_span = self.token.span;
+        let (end_kind, form) = if self.eat(&token::DotDotDot) {
+            (RangeEnd::Included(RangeSyntax::DotDotDot), "...")
+        } else if self.eat(&token::DotDotEq) {
+            (RangeEnd::Included(RangeSyntax::DotDotEq), "..=")
+        } else if self.eat(&token::DotDot) {
+            (self.excluded_range_end(op_span), "..")
+        } else {
+            panic!("impossible case: we already matched on a range-operator token")
+        };
+        let end = self.parse_pat_range_end_opt(&begin, form)?;
+        Ok(PatKind::Range(begin, end, respan(op_span, end_kind)))
+    }
+
+    fn fatal_unexpected_non_pat(
+        &mut self,
+        mut err: DiagnosticBuilder<'a>,
+        expected: Expected,
+    ) -> PResult<'a, P<Pat>> {
+        err.cancel();
+
+        let expected = expected.unwrap_or("pattern");
+        let msg = format!("expected {}, found {}", expected, self.this_token_descr());
+
+        let mut err = self.fatal(&msg);
+        err.span_label(self.token.span, format!("expected {}", expected));
+
+        let sp = self.sess.source_map().start_point(self.token.span);
+        if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow().get(&sp) {
+            self.sess.expr_parentheses_needed(&mut err, *sp, None);
+        }
+
+        Err(err)
+    }
+
+    /// Is the current token suitable as the start of a range patterns end?
+    fn is_pat_range_end_start(&self) -> bool {
+        self.token.is_path_start() // e.g. `MY_CONST`;
+            || self.token == token::Dot // e.g. `.5` for recovery;
+            || self.token.can_begin_literal_or_bool() // e.g. `42`.
+            || self.token.is_whole_expr()
+    }
+
+    /// Parse a range-to pattern, e.g. `..X` and `..=X` for recovery.
+    fn parse_pat_range_to(&mut self, re: RangeEnd, form: &str) -> PResult<'a, PatKind> {
+        let lo = self.prev_span;
+        let end = self.parse_pat_range_end()?;
+        let range_span = lo.to(end.span);
+        let begin = self.mk_expr(range_span, ExprKind::Err, ThinVec::new());
+
+        self.diagnostic()
+            .struct_span_err(range_span, &format!("`{}X` range patterns are not supported", form))
+            .span_suggestion(
+                range_span,
+                "try using the minimum value for the type",
+                format!("MIN{}{}", form, pprust::expr_to_string(&end)),
+                Applicability::HasPlaceholders,
+            )
+            .emit();
+
+        Ok(PatKind::Range(begin, end, respan(lo, re)))
+    }
+
+    /// Parse the end of a `X..Y`, `X..=Y`, or `X...Y` range pattern  or recover
+    /// if that end is missing treating it as `X..`, `X..=`, or `X...` respectively.
+    fn parse_pat_range_end_opt(&mut self, begin: &Expr, form: &str) -> PResult<'a, P<Expr>> {
+        if self.is_pat_range_end_start() {
+            // Parsing e.g. `X..=Y`.
+            self.parse_pat_range_end()
+        } else {
+            // Parsing e.g. `X..`.
+            let range_span = begin.span.to(self.prev_span);
+
+            self.diagnostic()
+                .struct_span_err(
+                    range_span,
+                    &format!("`X{}` range patterns are not supported", form),
+                )
+                .span_suggestion(
+                    range_span,
+                    "try using the maximum value for the type",
+                    format!("{}{}MAX", pprust::expr_to_string(&begin), form),
+                    Applicability::HasPlaceholders,
+                )
+                .emit();
+
+            Ok(self.mk_expr(range_span, ExprKind::Err, ThinVec::new()))
+        }
+    }
+
+    fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
+        if self.token.is_path_start() {
+            let lo = self.token.span;
+            let (qself, path) = if self.eat_lt() {
+                // Parse a qualified path
+                let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
+                (Some(qself), path)
+            } else {
+                // Parse an unqualified path
+                (None, self.parse_path(PathStyle::Expr)?)
+            };
+            let hi = self.prev_span;
+            Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), ThinVec::new()))
+        } else {
+            self.parse_literal_maybe_minus()
+        }
+    }
+
+    /// Is this the start of a pattern beginning with a path?
+    fn is_start_of_pat_with_path(&mut self) -> bool {
+        self.check_path()
+        // Just for recovery (see `can_be_ident`).
+        || self.token.is_ident() && !self.token.is_bool_lit() && !self.token.is_keyword(kw::In)
+    }
+
+    /// Would `parse_pat_ident` be appropriate here?
+    fn can_be_ident_pat(&mut self) -> bool {
+        self.check_ident()
+        && !self.token.is_bool_lit() // Avoid `true` or `false` as a binding as it is a literal.
+        && !self.token.is_path_segment_keyword() // Avoid e.g. `Self` as it is a path.
+        // Avoid `in`. Due to recovery in the list parser this messes with `for ( $pat in $expr )`.
+        && !self.token.is_keyword(kw::In)
+        && self.look_ahead(1, |t| match t.kind { // Try to do something more complex?
+            token::OpenDelim(token::Paren) // A tuple struct pattern.
+            | token::OpenDelim(token::Brace) // A struct pattern.
+            | token::DotDotDot | token::DotDotEq | token::DotDot // A range pattern.
+            | token::ModSep // A tuple / struct variant pattern.
+            | token::Not => false, // A macro expanding to a pattern.
+            _ => true,
+        })
+    }
+
+    /// Parses `ident` or `ident @ pat`.
+    /// Used by the copy foo and ref foo patterns to give a good
+    /// error message when parsing mistakes like `ref foo(a, b)`.
+    fn parse_pat_ident(&mut self, binding_mode: BindingMode) -> PResult<'a, PatKind> {
+        let ident = self.parse_ident()?;
+        let sub = if self.eat(&token::At) {
+            Some(self.parse_pat(Some("binding pattern"))?)
+        } else {
+            None
+        };
+
+        // Just to be friendly, if they write something like `ref Some(i)`,
+        // we end up here with `(` as the current token.
+        // This shortly leads to a parse error. Note that if there is no explicit
+        // binding mode then we do not end up here, because the lookahead
+        // will direct us over to `parse_enum_variant()`.
+        if self.token == token::OpenDelim(token::Paren) {
+            return Err(self.span_fatal(
+                self.prev_span,
+                "expected identifier, found enum pattern",
+            ))
+        }
+
+        Ok(PatKind::Ident(binding_mode, ident, sub))
+    }
+
+    /// Parse a struct ("record") pattern (e.g. `Foo { ... }` or `Foo::Bar { ... }`).
+    fn parse_pat_struct(&mut self, qself: Option<QSelf>, path: Path) -> PResult<'a, PatKind> {
+        if qself.is_some() {
+            let msg = "unexpected `{` after qualified path";
+            let mut err = self.fatal(msg);
+            err.span_label(self.token.span, msg);
+            return Err(err);
+        }
+
+        self.bump();
+        let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
+            e.emit();
+            self.recover_stmt();
+            (vec![], true)
+        });
+        self.bump();
+        Ok(PatKind::Struct(path, fields, etc))
+    }
+
+    /// Parse tuple struct or tuple variant pattern (e.g. `Foo(...)` or `Foo::Bar(...)`).
+    fn parse_pat_tuple_struct(&mut self, qself: Option<QSelf>, path: Path) -> PResult<'a, PatKind> {
+        if qself.is_some() {
+            let msg = "unexpected `(` after qualified path";
+            let mut err = self.fatal(msg);
+            err.span_label(self.token.span, msg);
+            return Err(err);
+        }
+        let (fields, _) = self.parse_paren_comma_seq(|p| p.parse_pat_with_or_inner())?;
+        Ok(PatKind::TupleStruct(path, fields))
+    }
+
+    /// Parses the fields of a struct-like pattern.
+    fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<FieldPat>, bool)> {
+        let mut fields = Vec::new();
+        let mut etc = false;
+        let mut ate_comma = true;
+        let mut delayed_err: Option<DiagnosticBuilder<'a>> = None;
+        let mut etc_span = None;
+
+        while self.token != token::CloseDelim(token::Brace) {
+            let attrs = match self.parse_outer_attributes() {
+                Ok(attrs) => attrs,
+                Err(err) => {
+                    if let Some(mut delayed) = delayed_err {
+                        delayed.emit();
+                    }
+                    return Err(err);
+                },
+            };
+            let lo = self.token.span;
+
+            // check that a comma comes after every field
+            if !ate_comma {
+                let err = self.struct_span_err(self.prev_span, "expected `,`");
+                if let Some(mut delayed) = delayed_err {
+                    delayed.emit();
+                }
+                return Err(err);
+            }
+            ate_comma = false;
+
+            if self.check(&token::DotDot) || self.token == token::DotDotDot {
+                etc = true;
+                let mut etc_sp = self.token.span;
+
+                self.recover_one_fewer_dotdot();
+                self.bump();  // `..` || `...`
+
+                if self.token == token::CloseDelim(token::Brace) {
+                    etc_span = Some(etc_sp);
+                    break;
+                }
+                let token_str = self.this_token_descr();
+                let mut err = self.fatal(&format!("expected `}}`, found {}", token_str));
+
+                err.span_label(self.token.span, "expected `}`");
+                let mut comma_sp = None;
+                if self.token == token::Comma { // Issue #49257
+                    let nw_span = self.sess.source_map().span_until_non_whitespace(self.token.span);
+                    etc_sp = etc_sp.to(nw_span);
+                    err.span_label(etc_sp,
+                                   "`..` must be at the end and cannot have a trailing comma");
+                    comma_sp = Some(self.token.span);
+                    self.bump();
+                    ate_comma = true;
+                }
+
+                etc_span = Some(etc_sp.until(self.token.span));
+                if self.token == token::CloseDelim(token::Brace) {
+                    // If the struct looks otherwise well formed, recover and continue.
+                    if let Some(sp) = comma_sp {
+                        err.span_suggestion_short(
+                            sp,
+                            "remove this comma",
+                            String::new(),
+                            Applicability::MachineApplicable,
+                        );
+                    }
+                    err.emit();
+                    break;
+                } else if self.token.is_ident() && ate_comma {
+                    // Accept fields coming after `..,`.
+                    // This way we avoid "pattern missing fields" errors afterwards.
+                    // We delay this error until the end in order to have a span for a
+                    // suggested fix.
+                    if let Some(mut delayed_err) = delayed_err {
+                        delayed_err.emit();
+                        return Err(err);
+                    } else {
+                        delayed_err = Some(err);
+                    }
+                } else {
+                    if let Some(mut err) = delayed_err {
+                        err.emit();
+                    }
+                    return Err(err);
+                }
+            }
+
+            fields.push(match self.parse_pat_field(lo, attrs) {
+                Ok(field) => field,
+                Err(err) => {
+                    if let Some(mut delayed_err) = delayed_err {
+                        delayed_err.emit();
+                    }
+                    return Err(err);
+                }
+            });
+            ate_comma = self.eat(&token::Comma);
+        }
+
+        if let Some(mut err) = delayed_err {
+            if let Some(etc_span) = etc_span {
+                err.multipart_suggestion(
+                    "move the `..` to the end of the field list",
+                    vec![
+                        (etc_span, String::new()),
+                        (self.token.span, format!("{}.. }}", if ate_comma { "" } else { ", " })),
+                    ],
+                    Applicability::MachineApplicable,
+                );
+            }
+            err.emit();
+        }
+        return Ok((fields, etc));
+    }
+
+    /// Recover on `...` as if it were `..` to avoid further errors.
+    /// See issue #46718.
+    fn recover_one_fewer_dotdot(&self) {
+        if self.token != token::DotDotDot {
+            return;
+        }
+
+        self.struct_span_err(self.token.span, "expected field pattern, found `...`")
+            .span_suggestion(
+                self.token.span,
+                "to omit remaining fields, use one fewer `.`",
+                "..".to_owned(),
+                Applicability::MachineApplicable
+            )
+            .emit();
+    }
+
+    fn parse_pat_field(&mut self, lo: Span, attrs: Vec<Attribute>) -> PResult<'a, FieldPat> {
+        // Check if a colon exists one ahead. This means we're parsing a fieldname.
+        let hi;
+        let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
+            // Parsing a pattern of the form `fieldname: pat`.
+            let fieldname = self.parse_field_name()?;
+            self.bump();
+            let pat = self.parse_pat_with_or_inner()?;
+            hi = pat.span;
+            (pat, fieldname, false)
+        } else {
+            // Parsing a pattern of the form `(box) (ref) (mut) fieldname`.
+            let is_box = self.eat_keyword(kw::Box);
+            let boxed_span = self.token.span;
+            let is_ref = self.eat_keyword(kw::Ref);
+            let is_mut = self.eat_keyword(kw::Mut);
+            let fieldname = self.parse_ident()?;
+            hi = self.prev_span;
+
+            let bind_type = match (is_ref, is_mut) {
+                (true, true) => BindingMode::ByRef(Mutability::Mutable),
+                (true, false) => BindingMode::ByRef(Mutability::Immutable),
+                (false, true) => BindingMode::ByValue(Mutability::Mutable),
+                (false, false) => BindingMode::ByValue(Mutability::Immutable),
+            };
+
+            let fieldpat = self.mk_pat_ident(boxed_span.to(hi), bind_type, fieldname);
+            let subpat = if is_box {
+                self.mk_pat(lo.to(hi), PatKind::Box(fieldpat))
+            } else {
+                fieldpat
+            };
+            (subpat, fieldname, true)
+        };
+
+        Ok(FieldPat {
+            ident: fieldname,
+            pat: subpat,
+            is_shorthand,
+            attrs: attrs.into(),
+            id: ast::DUMMY_NODE_ID,
+            span: lo.to(hi),
+            is_placeholder: false,
+        })
+    }
+
+    pub(super) fn mk_pat_ident(&self, span: Span, bm: BindingMode, ident: Ident) -> P<Pat> {
+        self.mk_pat(span, PatKind::Ident(bm, ident, None))
+    }
+
+    fn mk_pat(&self, span: Span, kind: PatKind) -> P<Pat> {
+        P(Pat { kind, span, id: ast::DUMMY_NODE_ID })
+    }
+}
diff --git a/src/librustc_parse/parser/path.rs b/src/librustc_parse/parser/path.rs
new file mode 100644
index 00000000000..68307440712
--- /dev/null
+++ b/src/librustc_parse/parser/path.rs
@@ -0,0 +1,497 @@
+use super::{Parser, TokenType};
+use crate::maybe_whole;
+use syntax::ast::{self, QSelf, Path, PathSegment, Ident, ParenthesizedArgs, AngleBracketedArgs};
+use syntax::ast::{AnonConst, GenericArg, AssocTyConstraint, AssocTyConstraintKind, BlockCheckMode};
+use syntax::ThinVec;
+use syntax::token::{self, Token};
+use syntax::source_map::{Span, BytePos};
+use syntax_pos::symbol::{kw, sym};
+
+use std::mem;
+use log::debug;
+use errors::{PResult, Applicability, pluralize};
+
+/// Specifies how to parse a path.
+#[derive(Copy, Clone, PartialEq)]
+pub enum PathStyle {
+    /// In some contexts, notably in expressions, paths with generic arguments are ambiguous
+    /// with something else. For example, in expressions `segment < ....` can be interpreted
+    /// as a comparison and `segment ( ....` can be interpreted as a function call.
+    /// In all such contexts the non-path interpretation is preferred by default for practical
+    /// reasons, but the path interpretation can be forced by the disambiguator `::`, e.g.
+    /// `x<y>` - comparisons, `x::<y>` - unambiguously a path.
+    Expr,
+    /// In other contexts, notably in types, no ambiguity exists and paths can be written
+    /// without the disambiguator, e.g., `x<y>` - unambiguously a path.
+    /// Paths with disambiguators are still accepted, `x::<Y>` - unambiguously a path too.
+    Type,
+    /// A path with generic arguments disallowed, e.g., `foo::bar::Baz`, used in imports,
+    /// visibilities or attributes.
+    /// Technically, this variant is unnecessary and e.g., `Expr` can be used instead
+    /// (paths in "mod" contexts have to be checked later for absence of generic arguments
+    /// anyway, due to macros), but it is used to avoid weird suggestions about expected
+    /// tokens when something goes wrong.
+    Mod,
+}
+
+impl<'a> Parser<'a> {
+    /// Parses a qualified path.
+    /// Assumes that the leading `<` has been parsed already.
+    ///
+    /// `qualified_path = <type [as trait_ref]>::path`
+    ///
+    /// # Examples
+    /// `<T>::default`
+    /// `<T as U>::a`
+    /// `<T as U>::F::a<S>` (without disambiguator)
+    /// `<T as U>::F::a::<S>` (with disambiguator)
+    pub(super) fn parse_qpath(&mut self, style: PathStyle) -> PResult<'a, (QSelf, Path)> {
+        let lo = self.prev_span;
+        let ty = self.parse_ty()?;
+
+        // `path` will contain the prefix of the path up to the `>`,
+        // if any (e.g., `U` in the `<T as U>::*` examples
+        // above). `path_span` has the span of that path, or an empty
+        // span in the case of something like `<T>::Bar`.
+        let (mut path, path_span);
+        if self.eat_keyword(kw::As) {
+            let path_lo = self.token.span;
+            path = self.parse_path(PathStyle::Type)?;
+            path_span = path_lo.to(self.prev_span);
+        } else {
+            path_span = self.token.span.to(self.token.span);
+            path = ast::Path { segments: Vec::new(), span: path_span };
+        }
+
+        // See doc comment for `unmatched_angle_bracket_count`.
+        self.expect(&token::Gt)?;
+        if self.unmatched_angle_bracket_count > 0 {
+            self.unmatched_angle_bracket_count -= 1;
+            debug!("parse_qpath: (decrement) count={:?}", self.unmatched_angle_bracket_count);
+        }
+
+        self.expect(&token::ModSep)?;
+
+        let qself = QSelf { ty, path_span, position: path.segments.len() };
+        self.parse_path_segments(&mut path.segments, style)?;
+
+        Ok((qself, Path { segments: path.segments, span: lo.to(self.prev_span) }))
+    }
+
+    /// Parses simple paths.
+    ///
+    /// `path = [::] segment+`
+    /// `segment = ident | ident[::]<args> | ident[::](args) [-> type]`
+    ///
+    /// # Examples
+    /// `a::b::C<D>` (without disambiguator)
+    /// `a::b::C::<D>` (with disambiguator)
+    /// `Fn(Args)` (without disambiguator)
+    /// `Fn::(Args)` (with disambiguator)
+    pub fn parse_path(&mut self, style: PathStyle) -> PResult<'a, Path> {
+        maybe_whole!(self, NtPath, |path| {
+            if style == PathStyle::Mod &&
+               path.segments.iter().any(|segment| segment.args.is_some()) {
+                self.diagnostic().span_err(path.span, "unexpected generic arguments in path");
+            }
+            path
+        });
+
+        let lo = self.meta_var_span.unwrap_or(self.token.span);
+        let mut segments = Vec::new();
+        let mod_sep_ctxt = self.token.span.ctxt();
+        if self.eat(&token::ModSep) {
+            segments.push(PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt)));
+        }
+        self.parse_path_segments(&mut segments, style)?;
+
+        Ok(Path { segments, span: lo.to(self.prev_span) })
+    }
+
+    /// Like `parse_path`, but also supports parsing `Word` meta items into paths for
+    /// backwards-compatibility. This is used when parsing derive macro paths in `#[derive]`
+    /// attributes.
+    fn parse_path_allowing_meta(&mut self, style: PathStyle) -> PResult<'a, Path> {
+        let meta_ident = match self.token.kind {
+            token::Interpolated(ref nt) => match **nt {
+                token::NtMeta(ref item) => match item.tokens.is_empty() {
+                    true => Some(item.path.clone()),
+                    false => None,
+                },
+                _ => None,
+            },
+            _ => None,
+        };
+        if let Some(path) = meta_ident {
+            self.bump();
+            return Ok(path);
+        }
+        self.parse_path(style)
+    }
+
+    /// Parse a list of paths inside `#[derive(path_0, ..., path_n)]`.
+    pub fn parse_derive_paths(&mut self) -> PResult<'a, Vec<Path>> {
+        self.expect(&token::OpenDelim(token::Paren))?;
+        let mut list = Vec::new();
+        while !self.eat(&token::CloseDelim(token::Paren)) {
+            let path = self.parse_path_allowing_meta(PathStyle::Mod)?;
+            list.push(path);
+            if !self.eat(&token::Comma) {
+                self.expect(&token::CloseDelim(token::Paren))?;
+                break
+            }
+        }
+        Ok(list)
+    }
+
+    pub(super) fn parse_path_segments(
+        &mut self,
+        segments: &mut Vec<PathSegment>,
+        style: PathStyle,
+    ) -> PResult<'a, ()> {
+        loop {
+            let segment = self.parse_path_segment(style)?;
+            if style == PathStyle::Expr {
+                // In order to check for trailing angle brackets, we must have finished
+                // recursing (`parse_path_segment` can indirectly call this function),
+                // that is, the next token must be the highlighted part of the below example:
+                //
+                // `Foo::<Bar as Baz<T>>::Qux`
+                //                      ^ here
+                //
+                // As opposed to the below highlight (if we had only finished the first
+                // recursion):
+                //
+                // `Foo::<Bar as Baz<T>>::Qux`
+                //                     ^ here
+                //
+                // `PathStyle::Expr` is only provided at the root invocation and never in
+                // `parse_path_segment` to recurse and therefore can be checked to maintain
+                // this invariant.
+                self.check_trailing_angle_brackets(&segment, token::ModSep);
+            }
+            segments.push(segment);
+
+            if self.is_import_coupler() || !self.eat(&token::ModSep) {
+                return Ok(());
+            }
+        }
+    }
+
+    pub(super) fn parse_path_segment(&mut self, style: PathStyle) -> PResult<'a, PathSegment> {
+        let ident = self.parse_path_segment_ident()?;
+
+        let is_args_start = |token: &Token| match token.kind {
+            token::Lt | token::BinOp(token::Shl) | token::OpenDelim(token::Paren)
+            | token::LArrow => true,
+            _ => false,
+        };
+        let check_args_start = |this: &mut Self| {
+            this.expected_tokens.extend_from_slice(
+                &[TokenType::Token(token::Lt), TokenType::Token(token::OpenDelim(token::Paren))]
+            );
+            is_args_start(&this.token)
+        };
+
+        Ok(if style == PathStyle::Type && check_args_start(self) ||
+              style != PathStyle::Mod && self.check(&token::ModSep)
+                                      && self.look_ahead(1, |t| is_args_start(t)) {
+            // We use `style == PathStyle::Expr` to check if this is in a recursion or not. If
+            // it isn't, then we reset the unmatched angle bracket count as we're about to start
+            // parsing a new path.
+            if style == PathStyle::Expr {
+                self.unmatched_angle_bracket_count = 0;
+                self.max_angle_bracket_count = 0;
+            }
+
+            // Generic arguments are found - `<`, `(`, `::<` or `::(`.
+            self.eat(&token::ModSep);
+            let lo = self.token.span;
+            let args = if self.eat_lt() {
+                // `<'a, T, A = U>`
+                let (args, constraints) =
+                    self.parse_generic_args_with_leaning_angle_bracket_recovery(style, lo)?;
+                self.expect_gt()?;
+                let span = lo.to(self.prev_span);
+                AngleBracketedArgs { args, constraints, span }.into()
+            } else {
+                // `(T, U) -> R`
+                let (inputs, _) = self.parse_paren_comma_seq(|p| p.parse_ty())?;
+                let span = ident.span.to(self.prev_span);
+                let output = if self.eat(&token::RArrow) {
+                    Some(self.parse_ty_common(false, false, false)?)
+                } else {
+                    None
+                };
+                ParenthesizedArgs { inputs, output, span }.into()
+            };
+
+            PathSegment { ident, args, id: ast::DUMMY_NODE_ID }
+        } else {
+            // Generic arguments are not found.
+            PathSegment::from_ident(ident)
+        })
+    }
+
+    pub(super) fn parse_path_segment_ident(&mut self) -> PResult<'a, Ident> {
+        match self.token.kind {
+            token::Ident(name, _) if name.is_path_segment_keyword() => {
+                let span = self.token.span;
+                self.bump();
+                Ok(Ident::new(name, span))
+            }
+            _ => self.parse_ident(),
+        }
+    }
+
+    /// Parses generic args (within a path segment) with recovery for extra leading angle brackets.
+    /// For the purposes of understanding the parsing logic of generic arguments, this function
+    /// can be thought of being the same as just calling `self.parse_generic_args()` if the source
+    /// had the correct amount of leading angle brackets.
+    ///
+    /// ```ignore (diagnostics)
+    /// bar::<<<<T as Foo>::Output>();
+    ///      ^^ help: remove extra angle brackets
+    /// ```
+    fn parse_generic_args_with_leaning_angle_bracket_recovery(
+        &mut self,
+        style: PathStyle,
+        lo: Span,
+    ) -> PResult<'a, (Vec<GenericArg>, Vec<AssocTyConstraint>)> {
+        // We need to detect whether there are extra leading left angle brackets and produce an
+        // appropriate error and suggestion. This cannot be implemented by looking ahead at
+        // upcoming tokens for a matching `>` character - if there are unmatched `<` tokens
+        // then there won't be matching `>` tokens to find.
+        //
+        // To explain how this detection works, consider the following example:
+        //
+        // ```ignore (diagnostics)
+        // bar::<<<<T as Foo>::Output>();
+        //      ^^ help: remove extra angle brackets
+        // ```
+        //
+        // Parsing of the left angle brackets starts in this function. We start by parsing the
+        // `<` token (incrementing the counter of unmatched angle brackets on `Parser` via
+        // `eat_lt`):
+        //
+        // *Upcoming tokens:* `<<<<T as Foo>::Output>;`
+        // *Unmatched count:* 1
+        // *`parse_path_segment` calls deep:* 0
+        //
+        // This has the effect of recursing as this function is called if a `<` character
+        // is found within the expected generic arguments:
+        //
+        // *Upcoming tokens:* `<<<T as Foo>::Output>;`
+        // *Unmatched count:* 2
+        // *`parse_path_segment` calls deep:* 1
+        //
+        // Eventually we will have recursed until having consumed all of the `<` tokens and
+        // this will be reflected in the count:
+        //
+        // *Upcoming tokens:* `T as Foo>::Output>;`
+        // *Unmatched count:* 4
+        // `parse_path_segment` calls deep:* 3
+        //
+        // The parser will continue until reaching the first `>` - this will decrement the
+        // unmatched angle bracket count and return to the parent invocation of this function
+        // having succeeded in parsing:
+        //
+        // *Upcoming tokens:* `::Output>;`
+        // *Unmatched count:* 3
+        // *`parse_path_segment` calls deep:* 2
+        //
+        // This will continue until the next `>` character which will also return successfully
+        // to the parent invocation of this function and decrement the count:
+        //
+        // *Upcoming tokens:* `;`
+        // *Unmatched count:* 2
+        // *`parse_path_segment` calls deep:* 1
+        //
+        // At this point, this function will expect to find another matching `>` character but
+        // won't be able to and will return an error. This will continue all the way up the
+        // call stack until the first invocation:
+        //
+        // *Upcoming tokens:* `;`
+        // *Unmatched count:* 2
+        // *`parse_path_segment` calls deep:* 0
+        //
+        // In doing this, we have managed to work out how many unmatched leading left angle
+        // brackets there are, but we cannot recover as the unmatched angle brackets have
+        // already been consumed. To remedy this, we keep a snapshot of the parser state
+        // before we do the above. We can then inspect whether we ended up with a parsing error
+        // and unmatched left angle brackets and if so, restore the parser state before we
+        // consumed any `<` characters to emit an error and consume the erroneous tokens to
+        // recover by attempting to parse again.
+        //
+        // In practice, the recursion of this function is indirect and there will be other
+        // locations that consume some `<` characters - as long as we update the count when
+        // this happens, it isn't an issue.
+
+        let is_first_invocation = style == PathStyle::Expr;
+        // Take a snapshot before attempting to parse - we can restore this later.
+        let snapshot = if is_first_invocation {
+            Some(self.clone())
+        } else {
+            None
+        };
+
+        debug!("parse_generic_args_with_leading_angle_bracket_recovery: (snapshotting)");
+        match self.parse_generic_args() {
+            Ok(value) => Ok(value),
+            Err(ref mut e) if is_first_invocation && self.unmatched_angle_bracket_count > 0 => {
+                // Cancel error from being unable to find `>`. We know the error
+                // must have been this due to a non-zero unmatched angle bracket
+                // count.
+                e.cancel();
+
+                // Swap `self` with our backup of the parser state before attempting to parse
+                // generic arguments.
+                let snapshot = mem::replace(self, snapshot.unwrap());
+
+                debug!(
+                    "parse_generic_args_with_leading_angle_bracket_recovery: (snapshot failure) \
+                     snapshot.count={:?}",
+                    snapshot.unmatched_angle_bracket_count,
+                );
+
+                // Eat the unmatched angle brackets.
+                for _ in 0..snapshot.unmatched_angle_bracket_count {
+                    self.eat_lt();
+                }
+
+                // Make a span over ${unmatched angle bracket count} characters.
+                let span = lo.with_hi(
+                    lo.lo() + BytePos(snapshot.unmatched_angle_bracket_count)
+                );
+                self.diagnostic()
+                    .struct_span_err(
+                        span,
+                        &format!(
+                            "unmatched angle bracket{}",
+                            pluralize!(snapshot.unmatched_angle_bracket_count)
+                        ),
+                    )
+                    .span_suggestion(
+                        span,
+                        &format!(
+                            "remove extra angle bracket{}",
+                            pluralize!(snapshot.unmatched_angle_bracket_count)
+                        ),
+                        String::new(),
+                        Applicability::MachineApplicable,
+                    )
+                    .emit();
+
+                // Try again without unmatched angle bracket characters.
+                self.parse_generic_args()
+            },
+            Err(e) => Err(e),
+        }
+    }
+
+    /// Parses (possibly empty) list of lifetime and type arguments and associated type bindings,
+    /// possibly including trailing comma.
+    fn parse_generic_args(&mut self) -> PResult<'a, (Vec<GenericArg>, Vec<AssocTyConstraint>)> {
+        let mut args = Vec::new();
+        let mut constraints = Vec::new();
+        let mut misplaced_assoc_ty_constraints: Vec<Span> = Vec::new();
+        let mut assoc_ty_constraints: Vec<Span> = Vec::new();
+
+        let args_lo = self.token.span;
+
+        loop {
+            if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
+                // Parse lifetime argument.
+                args.push(GenericArg::Lifetime(self.expect_lifetime()));
+                misplaced_assoc_ty_constraints.append(&mut assoc_ty_constraints);
+            } else if self.check_ident()
+                && self.look_ahead(1, |t| t == &token::Eq || t == &token::Colon)
+            {
+                // Parse associated type constraint.
+                let lo = self.token.span;
+                let ident = self.parse_ident()?;
+                let kind = if self.eat(&token::Eq) {
+                    AssocTyConstraintKind::Equality {
+                        ty: self.parse_ty()?,
+                    }
+                } else if self.eat(&token::Colon) {
+                    AssocTyConstraintKind::Bound {
+                        bounds: self.parse_generic_bounds(Some(self.prev_span))?,
+                    }
+                } else {
+                    unreachable!();
+                };
+
+                let span = lo.to(self.prev_span);
+
+                // Gate associated type bounds, e.g., `Iterator<Item: Ord>`.
+                if let AssocTyConstraintKind::Bound { .. } = kind {
+                    self.sess.gated_spans.gate(sym::associated_type_bounds, span);
+                }
+
+                constraints.push(AssocTyConstraint {
+                    id: ast::DUMMY_NODE_ID,
+                    ident,
+                    kind,
+                    span,
+                });
+                assoc_ty_constraints.push(span);
+            } else if self.check_const_arg() {
+                // Parse const argument.
+                let expr = if let token::OpenDelim(token::Brace) = self.token.kind {
+                    self.parse_block_expr(
+                        None, self.token.span, BlockCheckMode::Default, ThinVec::new()
+                    )?
+                } else if self.token.is_ident() {
+                    // FIXME(const_generics): to distinguish between idents for types and consts,
+                    // we should introduce a GenericArg::Ident in the AST and distinguish when
+                    // lowering to the HIR. For now, idents for const args are not permitted.
+                    if self.token.is_bool_lit() {
+                        self.parse_literal_maybe_minus()?
+                    } else {
+                        return Err(
+                            self.fatal("identifiers may currently not be used for const generics")
+                        );
+                    }
+                } else {
+                    self.parse_literal_maybe_minus()?
+                };
+                let value = AnonConst {
+                    id: ast::DUMMY_NODE_ID,
+                    value: expr,
+                };
+                args.push(GenericArg::Const(value));
+                misplaced_assoc_ty_constraints.append(&mut assoc_ty_constraints);
+            } else if self.check_type() {
+                // Parse type argument.
+                args.push(GenericArg::Type(self.parse_ty()?));
+                misplaced_assoc_ty_constraints.append(&mut assoc_ty_constraints);
+            } else {
+                break
+            }
+
+            if !self.eat(&token::Comma) {
+                break
+            }
+        }
+
+        // FIXME: we would like to report this in ast_validation instead, but we currently do not
+        // preserve ordering of generic parameters with respect to associated type binding, so we
+        // lose that information after parsing.
+        if misplaced_assoc_ty_constraints.len() > 0 {
+            let mut err = self.struct_span_err(
+                args_lo.to(self.prev_span),
+                "associated type bindings must be declared after generic parameters",
+            );
+            for span in misplaced_assoc_ty_constraints {
+                err.span_label(
+                    span,
+                    "this associated type binding should be moved after the generic parameters",
+                );
+            }
+            err.emit();
+        }
+
+        Ok((args, constraints))
+    }
+}
diff --git a/src/librustc_parse/parser/stmt.rs b/src/librustc_parse/parser/stmt.rs
new file mode 100644
index 00000000000..a5f20691d07
--- /dev/null
+++ b/src/librustc_parse/parser/stmt.rs
@@ -0,0 +1,482 @@
+use super::{Parser, Restrictions, PrevTokenKind, SemiColonMode, BlockMode};
+use super::expr::LhsExpr;
+use super::path::PathStyle;
+use super::pat::GateOr;
+use super::diagnostics::Error;
+use crate::maybe_whole;
+use crate::DirectoryOwnership;
+
+use syntax::ThinVec;
+use syntax::ptr::P;
+use syntax::ast;
+use syntax::ast::{DUMMY_NODE_ID, Stmt, StmtKind, Local, Block, BlockCheckMode, Expr, ExprKind};
+use syntax::ast::{Attribute, AttrStyle, VisibilityKind, MacStmtStyle, Mac, MacDelimiter};
+use syntax::util::classify;
+use syntax::token;
+use syntax::source_map::{respan, Span};
+use syntax::symbol::{kw, sym};
+
+use std::mem;
+use errors::{PResult, Applicability};
+
+impl<'a> Parser<'a> {
+    /// Parses a statement. This stops just before trailing semicolons on everything but items.
+    /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed.
+    pub fn parse_stmt(&mut self) -> PResult<'a, Option<Stmt>> {
+        Ok(self.parse_stmt_(true))
+    }
+
+    fn parse_stmt_(&mut self, macro_legacy_warnings: bool) -> Option<Stmt> {
+        self.parse_stmt_without_recovery(macro_legacy_warnings).unwrap_or_else(|mut e| {
+            e.emit();
+            self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
+            None
+        })
+    }
+
+    fn parse_stmt_without_recovery(
+        &mut self,
+        macro_legacy_warnings: bool,
+    ) -> PResult<'a, Option<Stmt>> {
+        maybe_whole!(self, NtStmt, |x| Some(x));
+
+        let attrs = self.parse_outer_attributes()?;
+        let lo = self.token.span;
+
+        Ok(Some(if self.eat_keyword(kw::Let) {
+            Stmt {
+                id: DUMMY_NODE_ID,
+                kind: StmtKind::Local(self.parse_local(attrs.into())?),
+                span: lo.to(self.prev_span),
+            }
+        } else if let Some(macro_def) = self.eat_macro_def(
+            &attrs,
+            &respan(lo, VisibilityKind::Inherited),
+            lo,
+        )? {
+            Stmt {
+                id: DUMMY_NODE_ID,
+                kind: StmtKind::Item(macro_def),
+                span: lo.to(self.prev_span),
+            }
+        // Starts like a simple path, being careful to avoid contextual keywords
+        // such as a union items, item with `crate` visibility or auto trait items.
+        // Our goal here is to parse an arbitrary path `a::b::c` but not something that starts
+        // like a path (1 token), but it fact not a path.
+        // `union::b::c` - path, `union U { ... }` - not a path.
+        // `crate::b::c` - path, `crate struct S;` - not a path.
+        } else if self.token.is_path_start() &&
+                  !self.token.is_qpath_start() &&
+                  !self.is_union_item() &&
+                  !self.is_crate_vis() &&
+                  !self.is_auto_trait_item() &&
+                  !self.is_async_fn() {
+            let path = self.parse_path(PathStyle::Expr)?;
+
+            if !self.eat(&token::Not) {
+                let expr = if self.check(&token::OpenDelim(token::Brace)) {
+                    self.parse_struct_expr(lo, path, ThinVec::new())?
+                } else {
+                    let hi = self.prev_span;
+                    self.mk_expr(lo.to(hi), ExprKind::Path(None, path), ThinVec::new())
+                };
+
+                let expr = self.with_res(Restrictions::STMT_EXPR, |this| {
+                    let expr = this.parse_dot_or_call_expr_with(expr, lo, attrs.into())?;
+                    this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr))
+                })?;
+
+                return Ok(Some(Stmt {
+                    id: DUMMY_NODE_ID,
+                    kind: StmtKind::Expr(expr),
+                    span: lo.to(self.prev_span),
+                }));
+            }
+
+            let (delim, tts) = self.expect_delimited_token_tree()?;
+            let hi = self.prev_span;
+
+            let style = if delim == MacDelimiter::Brace {
+                MacStmtStyle::Braces
+            } else {
+                MacStmtStyle::NoBraces
+            };
+
+            let mac = Mac {
+                path,
+                tts,
+                delim,
+                span: lo.to(hi),
+                prior_type_ascription: self.last_type_ascription,
+            };
+            let kind = if delim == MacDelimiter::Brace ||
+                          self.token == token::Semi || self.token == token::Eof {
+                StmtKind::Mac(P((mac, style, attrs.into())))
+            }
+            // We used to incorrectly stop parsing macro-expanded statements here.
+            // If the next token will be an error anyway but could have parsed with the
+            // earlier behavior, stop parsing here and emit a warning to avoid breakage.
+            else if macro_legacy_warnings && self.token.can_begin_expr() &&
+                match self.token.kind {
+                    // These can continue an expression, so we can't stop parsing and warn.
+                    token::OpenDelim(token::Paren) | token::OpenDelim(token::Bracket) |
+                    token::BinOp(token::Minus) | token::BinOp(token::Star) |
+                    token::BinOp(token::And) | token::BinOp(token::Or) |
+                    token::AndAnd | token::OrOr |
+                    token::DotDot | token::DotDotDot | token::DotDotEq => false,
+                    _ => true,
+                }
+            {
+                self.warn_missing_semicolon();
+                StmtKind::Mac(P((mac, style, attrs.into())))
+            } else {
+                let e = self.mk_expr(mac.span, ExprKind::Mac(mac), ThinVec::new());
+                let e = self.maybe_recover_from_bad_qpath(e, true)?;
+                let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
+                let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
+                StmtKind::Expr(e)
+            };
+            Stmt {
+                id: DUMMY_NODE_ID,
+                span: lo.to(hi),
+                kind,
+            }
+        } else {
+            // FIXME: Bad copy of attrs
+            let old_directory_ownership =
+                mem::replace(&mut self.directory.ownership, DirectoryOwnership::UnownedViaBlock);
+            let item = self.parse_item_(attrs.clone(), false, true)?;
+            self.directory.ownership = old_directory_ownership;
+
+            match item {
+                Some(i) => Stmt {
+                    id: DUMMY_NODE_ID,
+                    span: lo.to(i.span),
+                    kind: StmtKind::Item(i),
+                },
+                None => {
+                    let unused_attrs = |attrs: &[Attribute], s: &mut Self| {
+                        if !attrs.is_empty() {
+                            if s.prev_token_kind == PrevTokenKind::DocComment {
+                                s.span_fatal_err(s.prev_span, Error::UselessDocComment).emit();
+                            } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) {
+                                s.span_err(
+                                    s.token.span, "expected statement after outer attribute"
+                                );
+                            }
+                        }
+                    };
+
+                    // Do not attempt to parse an expression if we're done here.
+                    if self.token == token::Semi {
+                        unused_attrs(&attrs, self);
+                        self.bump();
+                        let mut last_semi = lo;
+                        while self.token == token::Semi {
+                            last_semi = self.token.span;
+                            self.bump();
+                        }
+                        // We are encoding a string of semicolons as an
+                        // an empty tuple that spans the excess semicolons
+                        // to preserve this info until the lint stage
+                        return Ok(Some(Stmt {
+                            id: DUMMY_NODE_ID,
+                            span: lo.to(last_semi),
+                            kind: StmtKind::Semi(self.mk_expr(lo.to(last_semi),
+                                ExprKind::Tup(Vec::new()),
+                                ThinVec::new()
+                            )),
+                        }));
+                    }
+
+                    if self.token == token::CloseDelim(token::Brace) {
+                        unused_attrs(&attrs, self);
+                        return Ok(None);
+                    }
+
+                    // Remainder are line-expr stmts.
+                    let e = self.parse_expr_res(
+                        Restrictions::STMT_EXPR, Some(attrs.into()))?;
+                    Stmt {
+                        id: DUMMY_NODE_ID,
+                        span: lo.to(e.span),
+                        kind: StmtKind::Expr(e),
+                    }
+                }
+            }
+        }))
+    }
+
+    /// Parses a local variable declaration.
+    fn parse_local(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Local>> {
+        let lo = self.prev_span;
+        let pat = self.parse_top_pat(GateOr::Yes)?;
+
+        let (err, ty) = if self.eat(&token::Colon) {
+            // Save the state of the parser before parsing type normally, in case there is a `:`
+            // instead of an `=` typo.
+            let parser_snapshot_before_type = self.clone();
+            let colon_sp = self.prev_span;
+            match self.parse_ty() {
+                Ok(ty) => (None, Some(ty)),
+                Err(mut err) => {
+                    // Rewind to before attempting to parse the type and continue parsing.
+                    let parser_snapshot_after_type = self.clone();
+                    mem::replace(self, parser_snapshot_before_type);
+
+                    let snippet = self.span_to_snippet(pat.span).unwrap();
+                    err.span_label(pat.span, format!("while parsing the type for `{}`", snippet));
+                    (Some((parser_snapshot_after_type, colon_sp, err)), None)
+                }
+            }
+        } else {
+            (None, None)
+        };
+        let init = match (self.parse_initializer(err.is_some()), err) {
+            (Ok(init), None) => {  // init parsed, ty parsed
+                init
+            }
+            (Ok(init), Some((_, colon_sp, mut err))) => {  // init parsed, ty error
+                // Could parse the type as if it were the initializer, it is likely there was a
+                // typo in the code: `:` instead of `=`. Add suggestion and emit the error.
+                err.span_suggestion_short(
+                    colon_sp,
+                    "use `=` if you meant to assign",
+                    " =".to_string(),
+                    Applicability::MachineApplicable
+                );
+                err.emit();
+                // As this was parsed successfully, continue as if the code has been fixed for the
+                // rest of the file. It will still fail due to the emitted error, but we avoid
+                // extra noise.
+                init
+            }
+            (Err(mut init_err), Some((snapshot, _, ty_err))) => {  // init error, ty error
+                init_err.cancel();
+                // Couldn't parse the type nor the initializer, only raise the type error and
+                // return to the parser state before parsing the type as the initializer.
+                // let x: <parse_error>;
+                mem::replace(self, snapshot);
+                return Err(ty_err);
+            }
+            (Err(err), None) => {  // init error, ty parsed
+                // Couldn't parse the initializer and we're not attempting to recover a failed
+                // parse of the type, return the error.
+                return Err(err);
+            }
+        };
+        let hi = if self.token == token::Semi {
+            self.token.span
+        } else {
+            self.prev_span
+        };
+        Ok(P(ast::Local {
+            ty,
+            pat,
+            init,
+            id: DUMMY_NODE_ID,
+            span: lo.to(hi),
+            attrs,
+        }))
+    }
+
+    /// Parses the RHS of a local variable declaration (e.g., '= 14;').
+    fn parse_initializer(&mut self, skip_eq: bool) -> PResult<'a, Option<P<Expr>>> {
+        if self.eat(&token::Eq) {
+            Ok(Some(self.parse_expr()?))
+        } else if skip_eq {
+            Ok(Some(self.parse_expr()?))
+        } else {
+            Ok(None)
+        }
+    }
+
+    fn is_auto_trait_item(&self) -> bool {
+        // auto trait
+        (self.token.is_keyword(kw::Auto) &&
+            self.is_keyword_ahead(1, &[kw::Trait]))
+        || // unsafe auto trait
+        (self.token.is_keyword(kw::Unsafe) &&
+         self.is_keyword_ahead(1, &[kw::Auto]) &&
+         self.is_keyword_ahead(2, &[kw::Trait]))
+    }
+
+    /// Parses a block. No inner attributes are allowed.
+    pub fn parse_block(&mut self) -> PResult<'a, P<Block>> {
+        maybe_whole!(self, NtBlock, |x| x);
+
+        let lo = self.token.span;
+
+        if !self.eat(&token::OpenDelim(token::Brace)) {
+            let sp = self.token.span;
+            let tok = self.this_token_descr();
+            let mut e = self.span_fatal(sp, &format!("expected `{{`, found {}", tok));
+            let do_not_suggest_help =
+                self.token.is_keyword(kw::In) || self.token == token::Colon;
+
+            if self.token.is_ident_named(sym::and) {
+                e.span_suggestion_short(
+                    self.token.span,
+                    "use `&&` instead of `and` for the boolean operator",
+                    "&&".to_string(),
+                    Applicability::MaybeIncorrect,
+                );
+            }
+            if self.token.is_ident_named(sym::or) {
+                e.span_suggestion_short(
+                    self.token.span,
+                    "use `||` instead of `or` for the boolean operator",
+                    "||".to_string(),
+                    Applicability::MaybeIncorrect,
+                );
+            }
+
+            // Check to see if the user has written something like
+            //
+            //    if (cond)
+            //      bar;
+            //
+            // which is valid in other languages, but not Rust.
+            match self.parse_stmt_without_recovery(false) {
+                Ok(Some(stmt)) => {
+                    if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace))
+                        || do_not_suggest_help {
+                        // If the next token is an open brace (e.g., `if a b {`), the place-
+                        // inside-a-block suggestion would be more likely wrong than right.
+                        e.span_label(sp, "expected `{`");
+                        return Err(e);
+                    }
+                    let mut stmt_span = stmt.span;
+                    // Expand the span to include the semicolon, if it exists.
+                    if self.eat(&token::Semi) {
+                        stmt_span = stmt_span.with_hi(self.prev_span.hi());
+                    }
+                    if let Ok(snippet) = self.span_to_snippet(stmt_span) {
+                        e.span_suggestion(
+                            stmt_span,
+                            "try placing this code inside a block",
+                            format!("{{ {} }}", snippet),
+                            // Speculative; has been misleading in the past (#46836).
+                            Applicability::MaybeIncorrect,
+                        );
+                    }
+                }
+                Err(mut e) => {
+                    self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
+                    e.cancel();
+                }
+                _ => ()
+            }
+            e.span_label(sp, "expected `{`");
+            return Err(e);
+        }
+
+        self.parse_block_tail(lo, BlockCheckMode::Default)
+    }
+
+    /// Parses a block. Inner attributes are allowed.
+    pub(super) fn parse_inner_attrs_and_block(
+        &mut self
+    ) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
+        maybe_whole!(self, NtBlock, |x| (Vec::new(), x));
+
+        let lo = self.token.span;
+        self.expect(&token::OpenDelim(token::Brace))?;
+        Ok((self.parse_inner_attributes()?,
+            self.parse_block_tail(lo, BlockCheckMode::Default)?))
+    }
+
+    /// Parses the rest of a block expression or function body.
+    /// Precondition: already parsed the '{'.
+    pub(super) fn parse_block_tail(
+        &mut self,
+        lo: Span,
+        s: BlockCheckMode
+    ) -> PResult<'a, P<Block>> {
+        let mut stmts = vec![];
+        while !self.eat(&token::CloseDelim(token::Brace)) {
+            if self.token == token::Eof {
+                break;
+            }
+            let stmt = match self.parse_full_stmt(false) {
+                Err(mut err) => {
+                    self.maybe_annotate_with_ascription(&mut err, false);
+                    err.emit();
+                    self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore);
+                    Some(Stmt {
+                        id: DUMMY_NODE_ID,
+                        kind: StmtKind::Expr(self.mk_expr_err(self.token.span)),
+                        span: self.token.span,
+                    })
+                }
+                Ok(stmt) => stmt,
+            };
+            if let Some(stmt) = stmt {
+                stmts.push(stmt);
+            } else {
+                // Found only `;` or `}`.
+                continue;
+            };
+        }
+        Ok(P(ast::Block {
+            stmts,
+            id: DUMMY_NODE_ID,
+            rules: s,
+            span: lo.to(self.prev_span),
+        }))
+    }
+
+    /// Parses a statement, including the trailing semicolon.
+    pub fn parse_full_stmt(&mut self, macro_legacy_warnings: bool) -> PResult<'a, Option<Stmt>> {
+        // Skip looking for a trailing semicolon when we have an interpolated statement.
+        maybe_whole!(self, NtStmt, |x| Some(x));
+
+        let mut stmt = match self.parse_stmt_without_recovery(macro_legacy_warnings)? {
+            Some(stmt) => stmt,
+            None => return Ok(None),
+        };
+
+        let mut eat_semi = true;
+        match stmt.kind {
+            StmtKind::Expr(ref expr) if self.token != token::Eof => {
+                // expression without semicolon
+                if classify::expr_requires_semi_to_be_stmt(expr) {
+                    // Just check for errors and recover; do not eat semicolon yet.
+                    if let Err(mut e) =
+                        self.expect_one_of(&[], &[token::Semi, token::CloseDelim(token::Brace)])
+                    {
+                        e.emit();
+                        self.recover_stmt();
+                        // Don't complain about type errors in body tail after parse error (#57383).
+                        let sp = expr.span.to(self.prev_span);
+                        stmt.kind = StmtKind::Expr(self.mk_expr_err(sp));
+                    }
+                }
+            }
+            StmtKind::Local(..) => {
+                // We used to incorrectly allow a macro-expanded let statement to lack a semicolon.
+                if macro_legacy_warnings && self.token != token::Semi {
+                    self.warn_missing_semicolon();
+                } else {
+                    self.expect_semi()?;
+                    eat_semi = false;
+                }
+            }
+            _ => {}
+        }
+
+        if eat_semi && self.eat(&token::Semi) {
+            stmt = stmt.add_trailing_semicolon();
+        }
+        stmt.span = stmt.span.to(self.prev_span);
+        Ok(Some(stmt))
+    }
+
+    fn warn_missing_semicolon(&self) {
+        self.diagnostic().struct_span_warn(self.token.span, {
+            &format!("expected `;`, found {}", self.this_token_descr())
+        }).note({
+            "this was erroneously allowed and will become a hard error in a future release"
+        }).emit();
+    }
+}
diff --git a/src/librustc_parse/parser/ty.rs b/src/librustc_parse/parser/ty.rs
new file mode 100644
index 00000000000..fccabee2404
--- /dev/null
+++ b/src/librustc_parse/parser/ty.rs
@@ -0,0 +1,460 @@
+use super::{Parser, PathStyle, PrevTokenKind, TokenType};
+use super::item::ParamCfg;
+
+use crate::{maybe_whole, maybe_recover_from_interpolated_ty_qpath};
+
+use syntax::ptr::P;
+use syntax::ast::{self, Ty, TyKind, MutTy, BareFnTy, FunctionRetTy, GenericParam, Lifetime, Ident};
+use syntax::ast::{TraitBoundModifier, TraitObjectSyntax, GenericBound, GenericBounds, PolyTraitRef};
+use syntax::ast::{Mutability, AnonConst, Mac};
+use syntax::token::{self, Token};
+use syntax::source_map::Span;
+use syntax::struct_span_fatal;
+use syntax_pos::symbol::kw;
+
+use errors::{PResult, Applicability, pluralize};
+
+/// Returns `true` if `IDENT t` can start a type -- `IDENT::a::b`, `IDENT<u8, u8>`,
+/// `IDENT<<u8 as Trait>::AssocTy>`.
+///
+/// Types can also be of the form `IDENT(u8, u8) -> u8`, however this assumes
+/// that `IDENT` is not the ident of a fn trait.
+fn can_continue_type_after_non_fn_ident(t: &Token) -> bool {
+    t == &token::ModSep || t == &token::Lt ||
+    t == &token::BinOp(token::Shl)
+}
+
+impl<'a> Parser<'a> {
+    /// Parses a type.
+    pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> {
+        self.parse_ty_common(true, true, false)
+    }
+
+    /// Parses a type in restricted contexts where `+` is not permitted.
+    ///
+    /// Example 1: `&'a TYPE`
+    ///     `+` is prohibited to maintain operator priority (P(+) < P(&)).
+    /// Example 2: `value1 as TYPE + value2`
+    ///     `+` is prohibited to avoid interactions with expression grammar.
+    pub(super) fn parse_ty_no_plus(&mut self) -> PResult<'a, P<Ty>> {
+        self.parse_ty_common(false, true, false)
+    }
+
+    /// Parses an optional return type `[ -> TY ]` in a function declaration.
+    pub(super) fn parse_ret_ty(&mut self, allow_plus: bool) -> PResult<'a, FunctionRetTy> {
+        if self.eat(&token::RArrow) {
+            Ok(FunctionRetTy::Ty(self.parse_ty_common(allow_plus, true, false)?))
+        } else {
+            Ok(FunctionRetTy::Default(self.token.span.shrink_to_lo()))
+        }
+    }
+
+    pub(super) fn parse_ty_common(&mut self, allow_plus: bool, allow_qpath_recovery: bool,
+                       allow_c_variadic: bool) -> PResult<'a, P<Ty>> {
+        maybe_recover_from_interpolated_ty_qpath!(self, allow_qpath_recovery);
+        maybe_whole!(self, NtTy, |x| x);
+
+        let lo = self.token.span;
+        let mut impl_dyn_multi = false;
+        let kind = if self.eat(&token::OpenDelim(token::Paren)) {
+            // `(TYPE)` is a parenthesized type.
+            // `(TYPE,)` is a tuple with a single field of type TYPE.
+            let mut ts = vec![];
+            let mut last_comma = false;
+            while self.token != token::CloseDelim(token::Paren) {
+                ts.push(self.parse_ty()?);
+                if self.eat(&token::Comma) {
+                    last_comma = true;
+                } else {
+                    last_comma = false;
+                    break;
+                }
+            }
+            let trailing_plus = self.prev_token_kind == PrevTokenKind::Plus;
+            self.expect(&token::CloseDelim(token::Paren))?;
+
+            if ts.len() == 1 && !last_comma {
+                let ty = ts.into_iter().nth(0).unwrap().into_inner();
+                let maybe_bounds = allow_plus && self.token.is_like_plus();
+                match ty.kind {
+                    // `(TY_BOUND_NOPAREN) + BOUND + ...`.
+                    TyKind::Path(None, ref path) if maybe_bounds => {
+                        self.parse_remaining_bounds(Vec::new(), path.clone(), lo, true)?
+                    }
+                    TyKind::TraitObject(ref bounds, TraitObjectSyntax::None)
+                            if maybe_bounds && bounds.len() == 1 && !trailing_plus => {
+                        let path = match bounds[0] {
+                            GenericBound::Trait(ref pt, ..) => pt.trait_ref.path.clone(),
+                            GenericBound::Outlives(..) => self.bug("unexpected lifetime bound"),
+                        };
+                        self.parse_remaining_bounds(Vec::new(), path, lo, true)?
+                    }
+                    // `(TYPE)`
+                    _ => TyKind::Paren(P(ty))
+                }
+            } else {
+                TyKind::Tup(ts)
+            }
+        } else if self.eat(&token::Not) {
+            // Never type `!`
+            TyKind::Never
+        } else if self.eat(&token::BinOp(token::Star)) {
+            // Raw pointer
+            TyKind::Ptr(self.parse_ptr()?)
+        } else if self.eat(&token::OpenDelim(token::Bracket)) {
+            // Array or slice
+            let t = self.parse_ty()?;
+            // Parse optional `; EXPR` in `[TYPE; EXPR]`
+            let t = match self.maybe_parse_fixed_length_of_vec()? {
+                None => TyKind::Slice(t),
+                Some(length) => TyKind::Array(t, AnonConst {
+                    id: ast::DUMMY_NODE_ID,
+                    value: length,
+                }),
+            };
+            self.expect(&token::CloseDelim(token::Bracket))?;
+            t
+        } else if self.check(&token::BinOp(token::And)) || self.check(&token::AndAnd) {
+            // Reference
+            self.expect_and()?;
+            self.parse_borrowed_pointee()?
+        } else if self.eat_keyword_noexpect(kw::Typeof) {
+            // `typeof(EXPR)`
+            // In order to not be ambiguous, the type must be surrounded by parens.
+            self.expect(&token::OpenDelim(token::Paren))?;
+            let e = AnonConst {
+                id: ast::DUMMY_NODE_ID,
+                value: self.parse_expr()?,
+            };
+            self.expect(&token::CloseDelim(token::Paren))?;
+            TyKind::Typeof(e)
+        } else if self.eat_keyword(kw::Underscore) {
+            // A type to be inferred `_`
+            TyKind::Infer
+        } else if self.token_is_bare_fn_keyword() {
+            // Function pointer type
+            self.parse_ty_bare_fn(Vec::new())?
+        } else if self.check_keyword(kw::For) {
+            // Function pointer type or bound list (trait object type) starting with a poly-trait.
+            //   `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
+            //   `for<'lt> Trait1<'lt> + Trait2 + 'a`
+            let lo = self.token.span;
+            let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
+            if self.token_is_bare_fn_keyword() {
+                self.parse_ty_bare_fn(lifetime_defs)?
+            } else {
+                let path = self.parse_path(PathStyle::Type)?;
+                let parse_plus = allow_plus && self.check_plus();
+                self.parse_remaining_bounds(lifetime_defs, path, lo, parse_plus)?
+            }
+        } else if self.eat_keyword(kw::Impl) {
+            // Always parse bounds greedily for better error recovery.
+            let bounds = self.parse_generic_bounds(None)?;
+            impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
+            TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds)
+        } else if self.check_keyword(kw::Dyn) &&
+                  (self.token.span.rust_2018() ||
+                   self.look_ahead(1, |t| t.can_begin_bound() &&
+                                          !can_continue_type_after_non_fn_ident(t))) {
+            self.bump(); // `dyn`
+            // Always parse bounds greedily for better error recovery.
+            let bounds = self.parse_generic_bounds(None)?;
+            impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
+            TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn)
+        } else if self.check(&token::Question) ||
+                  self.check_lifetime() && self.look_ahead(1, |t| t.is_like_plus()) {
+            // Bound list (trait object type)
+            TyKind::TraitObject(self.parse_generic_bounds_common(allow_plus, None)?,
+                                TraitObjectSyntax::None)
+        } else if self.eat_lt() {
+            // Qualified path
+            let (qself, path) = self.parse_qpath(PathStyle::Type)?;
+            TyKind::Path(Some(qself), path)
+        } else if self.token.is_path_start() {
+            // Simple path
+            let path = self.parse_path(PathStyle::Type)?;
+            if self.eat(&token::Not) {
+                // Macro invocation in type position
+                let (delim, tts) = self.expect_delimited_token_tree()?;
+                let mac = Mac {
+                    path,
+                    tts,
+                    delim,
+                    span: lo.to(self.prev_span),
+                    prior_type_ascription: self.last_type_ascription,
+                };
+                TyKind::Mac(mac)
+            } else {
+                // Just a type path or bound list (trait object type) starting with a trait.
+                //   `Type`
+                //   `Trait1 + Trait2 + 'a`
+                if allow_plus && self.check_plus() {
+                    self.parse_remaining_bounds(Vec::new(), path, lo, true)?
+                } else {
+                    TyKind::Path(None, path)
+                }
+            }
+        } else if self.check(&token::DotDotDot) {
+            if allow_c_variadic {
+                self.eat(&token::DotDotDot);
+                TyKind::CVarArgs
+            } else {
+                return Err(struct_span_fatal!(
+                    self.sess.span_diagnostic,
+                    self.token.span,
+                    E0743,
+                    "only foreign functions are allowed to be C-variadic",
+                ));
+            }
+        } else {
+            let msg = format!("expected type, found {}", self.this_token_descr());
+            let mut err = self.fatal(&msg);
+            err.span_label(self.token.span, "expected type");
+            self.maybe_annotate_with_ascription(&mut err, true);
+            return Err(err);
+        };
+
+        let span = lo.to(self.prev_span);
+        let ty = self.mk_ty(span, kind);
+
+        // Try to recover from use of `+` with incorrect priority.
+        self.maybe_report_ambiguous_plus(allow_plus, impl_dyn_multi, &ty);
+        self.maybe_recover_from_bad_type_plus(allow_plus, &ty)?;
+        self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery)
+    }
+
+    fn parse_remaining_bounds(&mut self, generic_params: Vec<GenericParam>, path: ast::Path,
+                              lo: Span, parse_plus: bool) -> PResult<'a, TyKind> {
+        let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_span));
+        let mut bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifier::None)];
+        if parse_plus {
+            self.eat_plus(); // `+`, or `+=` gets split and `+` is discarded
+            bounds.append(&mut self.parse_generic_bounds(Some(self.prev_span))?);
+        }
+        Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None))
+    }
+
+    fn parse_ptr(&mut self) -> PResult<'a, MutTy> {
+        let mutbl = self.parse_const_or_mut().unwrap_or_else(|| {
+            let span = self.prev_span;
+            let msg = "expected mut or const in raw pointer type";
+            self.struct_span_err(span, msg)
+                .span_label(span, msg)
+                .help("use `*mut T` or `*const T` as appropriate")
+                .emit();
+            Mutability::Immutable
+        });
+        let t = self.parse_ty_no_plus()?;
+        Ok(MutTy { ty: t, mutbl })
+    }
+
+    fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<'a, Option<P<ast::Expr>>> {
+        if self.eat(&token::Semi) {
+            Ok(Some(self.parse_expr()?))
+        } else {
+            Ok(None)
+        }
+    }
+
+    fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> {
+        let opt_lifetime = if self.check_lifetime() { Some(self.expect_lifetime()) } else { None };
+        let mutbl = self.parse_mutability();
+        let ty = self.parse_ty_no_plus()?;
+        return Ok(TyKind::Rptr(opt_lifetime, MutTy { ty, mutbl }));
+    }
+
+    /// Is the current token one of the keywords that signals a bare function type?
+    fn token_is_bare_fn_keyword(&mut self) -> bool {
+        self.check_keyword(kw::Fn) ||
+            self.check_keyword(kw::Unsafe) ||
+            self.check_keyword(kw::Extern)
+    }
+
+    /// Parses a `TyKind::BareFn` type.
+    fn parse_ty_bare_fn(&mut self, generic_params: Vec<GenericParam>) -> PResult<'a, TyKind> {
+        /*
+
+        [unsafe] [extern "ABI"] fn (S) -> T
+         ^~~~^           ^~~~^     ^~^    ^
+           |               |        |     |
+           |               |        |   Return type
+           |               |      Argument types
+           |               |
+           |              ABI
+        Function Style
+        */
+
+        let unsafety = self.parse_unsafety();
+        let abi = self.parse_extern_abi()?;
+        self.expect_keyword(kw::Fn)?;
+        let cfg = ParamCfg {
+            is_self_allowed: false,
+            allow_c_variadic: true,
+            is_name_required: |_| false,
+        };
+        let decl = self.parse_fn_decl(cfg, false)?;
+        Ok(TyKind::BareFn(P(BareFnTy {
+            abi,
+            unsafety,
+            generic_params,
+            decl,
+        })))
+    }
+
+    pub(super) fn parse_generic_bounds(&mut self,
+                                  colon_span: Option<Span>) -> PResult<'a, GenericBounds> {
+        self.parse_generic_bounds_common(true, colon_span)
+    }
+
+    /// Parses bounds of a type parameter `BOUND + BOUND + ...`, possibly with trailing `+`.
+    ///
+    /// ```
+    /// BOUND = TY_BOUND | LT_BOUND
+    /// LT_BOUND = LIFETIME (e.g., `'a`)
+    /// TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
+    /// TY_BOUND_NOPAREN = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g., `?for<'a: 'b> m::Trait<'a>`)
+    /// ```
+    fn parse_generic_bounds_common(&mut self,
+                                   allow_plus: bool,
+                                   colon_span: Option<Span>) -> PResult<'a, GenericBounds> {
+        let mut bounds = Vec::new();
+        let mut negative_bounds = Vec::new();
+        let mut last_plus_span = None;
+        let mut was_negative = false;
+        loop {
+            // This needs to be synchronized with `TokenKind::can_begin_bound`.
+            let is_bound_start = self.check_path() || self.check_lifetime() ||
+                                 self.check(&token::Not) || // used for error reporting only
+                                 self.check(&token::Question) ||
+                                 self.check_keyword(kw::For) ||
+                                 self.check(&token::OpenDelim(token::Paren));
+            if is_bound_start {
+                let lo = self.token.span;
+                let has_parens = self.eat(&token::OpenDelim(token::Paren));
+                let inner_lo = self.token.span;
+                let is_negative = self.eat(&token::Not);
+                let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
+                if self.token.is_lifetime() {
+                    if let Some(question_span) = question {
+                        self.span_err(question_span,
+                                      "`?` may only modify trait bounds, not lifetime bounds");
+                    }
+                    bounds.push(GenericBound::Outlives(self.expect_lifetime()));
+                    if has_parens {
+                        let inner_span = inner_lo.to(self.prev_span);
+                        self.expect(&token::CloseDelim(token::Paren))?;
+                        let mut err = self.struct_span_err(
+                            lo.to(self.prev_span),
+                            "parenthesized lifetime bounds are not supported"
+                        );
+                        if let Ok(snippet) = self.span_to_snippet(inner_span) {
+                            err.span_suggestion_short(
+                                lo.to(self.prev_span),
+                                "remove the parentheses",
+                                snippet.to_owned(),
+                                Applicability::MachineApplicable
+                            );
+                        }
+                        err.emit();
+                    }
+                } else {
+                    let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
+                    let path = self.parse_path(PathStyle::Type)?;
+                    if has_parens {
+                        self.expect(&token::CloseDelim(token::Paren))?;
+                    }
+                    let poly_span = lo.to(self.prev_span);
+                    if is_negative {
+                        was_negative = true;
+                        if let Some(sp) = last_plus_span.or(colon_span) {
+                            negative_bounds.push(sp.to(poly_span));
+                        }
+                    } else {
+                        let poly_trait = PolyTraitRef::new(lifetime_defs, path, poly_span);
+                        let modifier = if question.is_some() {
+                            TraitBoundModifier::Maybe
+                        } else {
+                            TraitBoundModifier::None
+                        };
+                        bounds.push(GenericBound::Trait(poly_trait, modifier));
+                    }
+                }
+            } else {
+                break
+            }
+
+            if !allow_plus || !self.eat_plus() {
+                break
+            } else {
+                last_plus_span = Some(self.prev_span);
+            }
+        }
+
+        if !negative_bounds.is_empty() || was_negative {
+            let negative_bounds_len = negative_bounds.len();
+            let last_span = negative_bounds.last().map(|sp| *sp);
+            let mut err = self.struct_span_err(
+                negative_bounds,
+                "negative trait bounds are not supported",
+            );
+            if let Some(sp) = last_span {
+                err.span_label(sp, "negative trait bounds are not supported");
+            }
+            if let Some(bound_list) = colon_span {
+                let bound_list = bound_list.to(self.prev_span);
+                let mut new_bound_list = String::new();
+                if !bounds.is_empty() {
+                    let mut snippets = bounds.iter().map(|bound| bound.span())
+                        .map(|span| self.span_to_snippet(span));
+                    while let Some(Ok(snippet)) = snippets.next() {
+                        new_bound_list.push_str(" + ");
+                        new_bound_list.push_str(&snippet);
+                    }
+                    new_bound_list = new_bound_list.replacen(" +", ":", 1);
+                }
+                err.span_suggestion_hidden(
+                    bound_list,
+                    &format!("remove the trait bound{}", pluralize!(negative_bounds_len)),
+                    new_bound_list,
+                    Applicability::MachineApplicable,
+                );
+            }
+            err.emit();
+        }
+
+        return Ok(bounds);
+    }
+
+    pub(super) fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> {
+        if self.eat_keyword(kw::For) {
+            self.expect_lt()?;
+            let params = self.parse_generic_params()?;
+            self.expect_gt()?;
+            // We rely on AST validation to rule out invalid cases: There must not be type
+            // parameters, and the lifetime parameters must not have bounds.
+            Ok(params)
+        } else {
+            Ok(Vec::new())
+        }
+    }
+
+    pub fn check_lifetime(&mut self) -> bool {
+        self.expected_tokens.push(TokenType::Lifetime);
+        self.token.is_lifetime()
+    }
+
+    /// Parses a single lifetime `'a` or panics.
+    pub fn expect_lifetime(&mut self) -> Lifetime {
+        if let Some(ident) = self.token.lifetime() {
+            let span = self.token.span;
+            self.bump();
+            Lifetime { ident: Ident::new(ident.name, span), id: ast::DUMMY_NODE_ID }
+        } else {
+            self.span_bug(self.token.span, "not a lifetime")
+        }
+    }
+
+    pub(super) fn mk_ty(&self, span: Span, kind: TyKind) -> P<Ty> {
+        P(Ty { kind, span, id: ast::DUMMY_NODE_ID })
+    }
+}
diff --git a/src/librustc_parse/validate_attr.rs b/src/librustc_parse/validate_attr.rs
new file mode 100644
index 00000000000..bbe0dc1c35f
--- /dev/null
+++ b/src/librustc_parse/validate_attr.rs
@@ -0,0 +1,111 @@
+//! Meta-syntax validation logic of attributes for post-expansion.
+
+use errors::{PResult, Applicability};
+use syntax::ast::{self, Attribute, AttrKind, Ident, MetaItem};
+use syntax::attr::{AttributeTemplate, mk_name_value_item_str};
+use syntax::early_buffered_lints::BufferedEarlyLintId;
+use syntax::feature_gate::BUILTIN_ATTRIBUTE_MAP;
+use syntax::token;
+use syntax::tokenstream::TokenTree;
+use syntax::sess::ParseSess;
+use syntax_pos::{Symbol, sym};
+
+pub fn check_meta(sess: &ParseSess, attr: &Attribute) {
+    let attr_info =
+        attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name)).map(|a| **a);
+
+    // Check input tokens for built-in and key-value attributes.
+    match attr_info {
+        // `rustc_dummy` doesn't have any restrictions specific to built-in attributes.
+        Some((name, _, template, _)) if name != sym::rustc_dummy =>
+            check_builtin_attribute(sess, attr, name, template),
+        _ => if let Some(TokenTree::Token(token)) = attr.get_normal_item().tokens.trees().next() {
+            if token == token::Eq {
+                // All key-value attributes are restricted to meta-item syntax.
+                parse_meta(sess, attr).map_err(|mut err| err.emit()).ok();
+            }
+        }
+    }
+}
+
+pub fn parse_meta<'a>(sess: &'a ParseSess, attr: &Attribute) -> PResult<'a, MetaItem> {
+    Ok(match attr.kind {
+        AttrKind::Normal(ref item) => MetaItem {
+            path: item.path.clone(),
+            kind: super::parse_in_attr(sess, attr, |p| p.parse_meta_item_kind())?,
+            span: attr.span,
+        },
+        AttrKind::DocComment(comment) => {
+            mk_name_value_item_str(Ident::new(sym::doc, attr.span), comment, attr.span)
+        }
+    })
+}
+
+pub fn check_builtin_attribute(
+    sess: &ParseSess,
+    attr: &Attribute,
+    name: Symbol,
+    template: AttributeTemplate,
+) {
+    // Some special attributes like `cfg` must be checked
+    // before the generic check, so we skip them here.
+    let should_skip = |name| name == sym::cfg;
+    // Some of previously accepted forms were used in practice,
+    // report them as warnings for now.
+    let should_warn = |name| name == sym::doc || name == sym::ignore ||
+                             name == sym::inline || name == sym::link ||
+                             name == sym::test || name == sym::bench;
+
+    match parse_meta(sess, attr) {
+        Ok(meta) => if !should_skip(name) && !template.compatible(&meta.kind) {
+            let error_msg = format!("malformed `{}` attribute input", name);
+            let mut msg = "attribute must be of the form ".to_owned();
+            let mut suggestions = vec![];
+            let mut first = true;
+            if template.word {
+                first = false;
+                let code = format!("#[{}]", name);
+                msg.push_str(&format!("`{}`", &code));
+                suggestions.push(code);
+            }
+            if let Some(descr) = template.list {
+                if !first {
+                    msg.push_str(" or ");
+                }
+                first = false;
+                let code = format!("#[{}({})]", name, descr);
+                msg.push_str(&format!("`{}`", &code));
+                suggestions.push(code);
+            }
+            if let Some(descr) = template.name_value_str {
+                if !first {
+                    msg.push_str(" or ");
+                }
+                let code = format!("#[{} = \"{}\"]", name, descr);
+                msg.push_str(&format!("`{}`", &code));
+                suggestions.push(code);
+            }
+            if should_warn(name) {
+                sess.buffer_lint(
+                    BufferedEarlyLintId::IllFormedAttributeInput,
+                    meta.span,
+                    ast::CRATE_NODE_ID,
+                    &msg,
+                );
+            } else {
+                sess.span_diagnostic.struct_span_err(meta.span, &error_msg)
+                    .span_suggestions(
+                        meta.span,
+                        if suggestions.len() == 1 {
+                            "must be of the form"
+                        } else {
+                            "the following are the possible correct uses"
+                        },
+                        suggestions.into_iter(),
+                        Applicability::HasPlaceholders,
+                    ).emit();
+            }
+        }
+        Err(mut err) => err.emit(),
+    }
+}
diff --git a/src/librustc_passes/Cargo.toml b/src/librustc_passes/Cargo.toml
index 9d29a230314..556189208f1 100644
--- a/src/librustc_passes/Cargo.toml
+++ b/src/librustc_passes/Cargo.toml
@@ -12,8 +12,9 @@ path = "lib.rs"
 log = "0.4"
 rustc = { path = "../librustc" }
 rustc_data_structures = { path = "../librustc_data_structures" }
+rustc_index = { path = "../librustc_index" }
+rustc_parse = { path = "../librustc_parse" }
+rustc_target = { path = "../librustc_target" }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
-rustc_target = { path = "../librustc_target" }
-rustc_index = { path = "../librustc_index" }
diff --git a/src/librustc_passes/ast_validation.rs b/src/librustc_passes/ast_validation.rs
index a45035f123f..ec5572914d8 100644
--- a/src/librustc_passes/ast_validation.rs
+++ b/src/librustc_passes/ast_validation.rs
@@ -7,15 +7,15 @@
 // or type checking or some other kind of complex analysis.
 
 use std::mem;
-use syntax::print::pprust;
 use rustc::lint;
 use rustc::session::Session;
 use rustc_data_structures::fx::FxHashMap;
+use rustc_parse::validate_attr;
 use syntax::ast::*;
 use syntax::attr;
 use syntax::expand::is_proc_macro_attr;
 use syntax::feature_gate::is_builtin_attr;
-use syntax::parse::validate_attr;
+use syntax::print::pprust;
 use syntax::source_map::Spanned;
 use syntax::symbol::{kw, sym};
 use syntax::visit::{self, Visitor};
diff --git a/src/librustc_save_analysis/Cargo.toml b/src/librustc_save_analysis/Cargo.toml
index 2d93585e50e..50b3be6dca1 100644
--- a/src/librustc_save_analysis/Cargo.toml
+++ b/src/librustc_save_analysis/Cargo.toml
@@ -13,6 +13,7 @@ log = "0.4"
 rustc = { path = "../librustc" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_codegen_utils = { path = "../librustc_codegen_utils" }
+rustc_parse = { path = "../librustc_parse" }
 serde_json = "1"
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
diff --git a/src/librustc_save_analysis/span_utils.rs b/src/librustc_save_analysis/span_utils.rs
index 4d0780cf94d..f2f512bc8e5 100644
--- a/src/librustc_save_analysis/span_utils.rs
+++ b/src/librustc_save_analysis/span_utils.rs
@@ -1,8 +1,6 @@
-use rustc::session::Session;
-
 use crate::generated_code;
-
-use syntax::parse::lexer::{self, StringReader};
+use rustc::session::Session;
+use rustc_parse::lexer::{self, StringReader};
 use syntax::token::{self, TokenKind};
 use syntax_pos::*;
 
diff --git a/src/librustdoc/html/highlight.rs b/src/librustdoc/html/highlight.rs
index 71a44c0ebdb..bf4a1440e1b 100644
--- a/src/librustdoc/html/highlight.rs
+++ b/src/librustdoc/html/highlight.rs
@@ -11,10 +11,10 @@ use std::fmt::Display;
 use std::io;
 use std::io::prelude::*;
 
-use syntax::source_map::SourceMap;
-use syntax::parse::lexer;
+use rustc_parse::lexer;
 use syntax::token::{self, Token};
 use syntax::sess::ParseSess;
+use syntax::source_map::SourceMap;
 use syntax::symbol::{kw, sym};
 use syntax_expand::config::process_configure_mod;
 use syntax_pos::{Span, FileName};
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 13b8809e23e..86e0f22db50 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -29,6 +29,7 @@ extern crate rustc_resolve;
 extern crate rustc_lint;
 extern crate rustc_interface;
 extern crate rustc_metadata;
+extern crate rustc_parse;
 extern crate rustc_target;
 extern crate rustc_typeck;
 extern crate rustc_lexer;
diff --git a/src/librustdoc/passes/check_code_block_syntax.rs b/src/librustdoc/passes/check_code_block_syntax.rs
index 405f3a70e0e..5c4c975cec0 100644
--- a/src/librustdoc/passes/check_code_block_syntax.rs
+++ b/src/librustdoc/passes/check_code_block_syntax.rs
@@ -1,5 +1,5 @@
 use errors::Applicability;
-use syntax::parse::lexer::{StringReader as Lexer};
+use rustc_parse::lexer::{StringReader as Lexer};
 use syntax::token;
 use syntax::sess::ParseSess;
 use syntax::source_map::FilePathMapping;
diff --git a/src/librustdoc/test.rs b/src/librustdoc/test.rs
index e4cf1bb0bb9..553ef6a9c47 100644
--- a/src/librustdoc/test.rs
+++ b/src/librustdoc/test.rs
@@ -399,7 +399,8 @@ pub fn make_test(s: &str,
     // Uses libsyntax to parse the doctest and find if there's a main fn and the extern
     // crate already is included.
     let (already_has_main, already_has_extern_crate, found_macro) = with_globals(edition, || {
-        use crate::syntax::{parse, sess::ParseSess, source_map::FilePathMapping};
+        use crate::syntax::{sess::ParseSess, source_map::FilePathMapping};
+        use rustc_parse::maybe_new_parser_from_source_str;
         use errors::emitter::EmitterWriter;
         use errors::Handler;
 
@@ -418,7 +419,7 @@ pub fn make_test(s: &str,
         let mut found_extern_crate = cratename.is_none();
         let mut found_macro = false;
 
-        let mut parser = match parse::maybe_new_parser_from_source_str(&sess, filename, source) {
+        let mut parser = match maybe_new_parser_from_source_str(&sess, filename, source) {
             Ok(p) => p,
             Err(errs) => {
                 for mut err in errs {
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index b57d2238991..170d089d4bb 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -537,7 +537,7 @@ pub struct Pat {
 impl Pat {
     /// Attempt reparsing the pattern as a type.
     /// This is intended for use by diagnostics.
-    pub(super) fn to_ty(&self) -> Option<P<Ty>> {
+    pub fn to_ty(&self) -> Option<P<Ty>> {
         let kind = match &self.kind {
             // In a type expression `_` is an inference variable.
             PatKind::Wild => TyKind::Infer,
@@ -1031,7 +1031,7 @@ impl Expr {
         }
     }
 
-    fn to_bound(&self) -> Option<GenericBound> {
+    pub fn to_bound(&self) -> Option<GenericBound> {
         match &self.kind {
             ExprKind::Path(None, path) => Some(GenericBound::Trait(
                 PolyTraitRef::new(Vec::new(), path.clone(), self.span),
@@ -1042,7 +1042,7 @@ impl Expr {
     }
 
     /// Attempts to reparse as `Ty` (for diagnostic purposes).
-    pub(super) fn to_ty(&self) -> Option<P<Ty>> {
+    pub fn to_ty(&self) -> Option<P<Ty>> {
         let kind = match &self.kind {
             // Trivial conversions.
             ExprKind::Path(qself, path) => TyKind::Path(qself.clone(), path.clone()),
diff --git a/src/libsyntax/attr/builtin.rs b/src/libsyntax/attr/builtin.rs
index 3ac9abb7223..d0a31b330ab 100644
--- a/src/libsyntax/attr/builtin.rs
+++ b/src/libsyntax/attr/builtin.rs
@@ -24,9 +24,9 @@ enum AttrError {
 /// Only top-level shape (`#[attr]` vs `#[attr(...)]` vs `#[attr = ...]`) is considered now.
 #[derive(Clone, Copy)]
 pub struct AttributeTemplate {
-    crate word: bool,
-    crate list: Option<&'static str>,
-    crate name_value_str: Option<&'static str>,
+    pub word: bool,
+    pub list: Option<&'static str>,
+    pub name_value_str: Option<&'static str>,
 }
 
 impl AttributeTemplate {
diff --git a/src/libsyntax/attr/mod.rs b/src/libsyntax/attr/mod.rs
index d458549e298..29eff5c2981 100644
--- a/src/libsyntax/attr/mod.rs
+++ b/src/libsyntax/attr/mod.rs
@@ -277,7 +277,7 @@ impl MetaItem {
 }
 
 impl AttrItem {
-    crate fn meta(&self, span: Span) -> Option<MetaItem> {
+    pub fn meta(&self, span: Span) -> Option<MetaItem> {
         let mut tokens = self.tokens.trees().peekable();
         Some(MetaItem {
             path: self.path.clone(),
diff --git a/src/libsyntax/error_codes.rs b/src/libsyntax/error_codes.rs
index c23c8d65a7f..0e81de7d4a7 100644
--- a/src/libsyntax/error_codes.rs
+++ b/src/libsyntax/error_codes.rs
@@ -4,28 +4,6 @@
 // `:set tw=0` to disable.
 register_diagnostics! {
 
-E0178: r##"
-In types, the `+` type operator has low precedence, so it is often necessary
-to use parentheses.
-
-For example:
-
-```compile_fail,E0178
-trait Foo {}
-
-struct Bar<'a> {
-    w: &'a Foo + Copy,   // error, use &'a (Foo + Copy)
-    x: &'a Foo + 'a,     // error, use &'a (Foo + 'a)
-    y: &'a mut Foo + 'a, // error, use &'a mut (Foo + 'a)
-    z: fn() -> Foo + 'a, // error, use fn() -> (Foo + 'a)
-}
-```
-
-More details can be found in [RFC 438].
-
-[RFC 438]: https://github.com/rust-lang/rfcs/pull/438
-"##,
-
 E0536: r##"
 The `not` cfg-predicate was malformed.
 
@@ -278,106 +256,6 @@ pub fn something() {}
 ```
 "##,
 
-E0583: r##"
-A file wasn't found for an out-of-line module.
-
-Erroneous code example:
-
-```ignore (compile_fail not working here; see Issue #43707)
-mod file_that_doesnt_exist; // error: file not found for module
-
-fn main() {}
-```
-
-Please be sure that a file corresponding to the module exists. If you
-want to use a module named `file_that_doesnt_exist`, you need to have a file
-named `file_that_doesnt_exist.rs` or `file_that_doesnt_exist/mod.rs` in the
-same directory.
-"##,
-
-E0584: r##"
-A doc comment that is not attached to anything has been encountered.
-
-Erroneous code example:
-
-```compile_fail,E0584
-trait Island {
-    fn lost();
-
-    /// I'm lost!
-}
-```
-
-A little reminder: a doc comment has to be placed before the item it's supposed
-to document. So if you want to document the `Island` trait, you need to put a
-doc comment before it, not inside it. Same goes for the `lost` method: the doc
-comment needs to be before it:
-
-```
-/// I'm THE island!
-trait Island {
-    /// I'm lost!
-    fn lost();
-}
-```
-"##,
-
-E0585: r##"
-A documentation comment that doesn't document anything was found.
-
-Erroneous code example:
-
-```compile_fail,E0585
-fn main() {
-    // The following doc comment will fail:
-    /// This is a useless doc comment!
-}
-```
-
-Documentation comments need to be followed by items, including functions,
-types, modules, etc. Examples:
-
-```
-/// I'm documenting the following struct:
-struct Foo;
-
-/// I'm documenting the following function:
-fn foo() {}
-```
-"##,
-
-E0586: r##"
-An inclusive range was used with no end.
-
-Erroneous code example:
-
-```compile_fail,E0586
-fn main() {
-    let tmp = vec![0, 1, 2, 3, 4, 4, 3, 3, 2, 1];
-    let x = &tmp[1..=]; // error: inclusive range was used with no end
-}
-```
-
-An inclusive range needs an end in order to *include* it. If you just need a
-start and no end, use a non-inclusive range (with `..`):
-
-```
-fn main() {
-    let tmp = vec![0, 1, 2, 3, 4, 4, 3, 3, 2, 1];
-    let x = &tmp[1..]; // ok!
-}
-```
-
-Or put an end to your inclusive range:
-
-```
-fn main() {
-    let tmp = vec![0, 1, 2, 3, 4, 4, 3, 3, 2, 1];
-    let x = &tmp[1..=3]; // ok!
-}
-```
-"##,
-
 E0589: r##"
 The value of `N` that was specified for `repr(align(N))` was not a power
 of two, or was greater than 2^29.
@@ -446,35 +324,6 @@ and likely to change in the future.
 
 "##,
 
-E0704: r##"
-This error indicates that a incorrect visibility restriction was specified.
-
-Example of erroneous code:
-
-```compile_fail,E0704
-mod foo {
-    pub(foo) struct Bar {
-        x: i32
-    }
-}
-```
-
-To make struct `Bar` only visible in module `foo` the `in` keyword should be
-used:
-```
-mod foo {
-    pub(in crate::foo) struct Bar {
-        x: i32
-    }
-}
-# fn main() {}
-```
-
-For more information see the Rust Reference on [Visibility].
-
-[Visibility]: https://doc.rust-lang.org/reference/visibility-and-privacy.html
-"##,
-
 E0705: r##"
 A `#![feature]` attribute was declared for a feature that is stable in
 the current edition, but not in all editions.
@@ -504,20 +353,6 @@ Delete the offending feature attribute, or add it to the list of allowed
 features in the `-Z allow_features` flag.
 "##,
 
-E0743: r##"
-C-variadic has been used on a non-foreign function.
-
-Erroneous code example:
-
-```compile_fail,E0743
-fn foo2(x: u8, ...) {} // error!
-```
-
-Only foreign functions can use C-variadic (`...`). It is used to give an
-undefined number of parameters to a given function (like `printf` in C). The
-equivalent in Rust would be to use macros directly.
-"##,
-
 ;
 
     E0539, // incorrect meta item
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 7fecc87a18f..317fcf29389 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -26,8 +26,6 @@ pub use rustc_data_structures::thin_vec::ThinVec;
 use ast::AttrId;
 use syntax_pos::edition::Edition;
 
-pub const MACRO_ARGUMENTS: Option<&'static str> = Some("macro arguments");
-
 #[macro_export]
 macro_rules! unwrap_or {
     ($opt:expr, $default:expr) => {
@@ -82,10 +80,10 @@ pub mod diagnostics {
 pub mod error_codes;
 
 pub mod util {
-    crate mod classify;
+    pub mod classify;
     pub mod comments;
     pub mod lev_distance;
-    crate mod literal;
+    pub mod literal;
     pub mod node_count;
     pub mod parser;
     pub mod map_in_place;
@@ -100,7 +98,6 @@ pub mod source_map;
 pub mod entry;
 pub mod feature_gate;
 pub mod mut_visit;
-pub mod parse;
 pub mod ptr;
 pub mod show_span;
 pub use syntax_pos::edition;
diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
deleted file mode 100644
index f2d5ff3440e..00000000000
--- a/src/libsyntax/parse/lexer/mod.rs
+++ /dev/null
@@ -1,643 +0,0 @@
-use crate::token::{self, Token, TokenKind};
-use crate::sess::ParseSess;
-use crate::symbol::{sym, Symbol};
-use crate::util::comments;
-
-use errors::{FatalError, DiagnosticBuilder};
-use syntax_pos::{BytePos, Pos, Span};
-use rustc_lexer::Base;
-use rustc_lexer::unescape;
-
-use std::char;
-use std::convert::TryInto;
-use rustc_data_structures::sync::Lrc;
-use log::debug;
-
-mod tokentrees;
-mod unicode_chars;
-mod unescape_error_reporting;
-use unescape_error_reporting::{emit_unescape_error, push_escaped_char};
-
-#[derive(Clone, Debug)]
-pub struct UnmatchedBrace {
-    pub expected_delim: token::DelimToken,
-    pub found_delim: Option<token::DelimToken>,
-    pub found_span: Span,
-    pub unclosed_span: Option<Span>,
-    pub candidate_span: Option<Span>,
-}
-
-pub struct StringReader<'a> {
-    sess: &'a ParseSess,
-    /// Initial position, read-only.
-    start_pos: BytePos,
-    /// The absolute offset within the source_map of the current character.
-    // FIXME(#64197): `pub` is needed by tests for now.
-    pub pos: BytePos,
-    /// Stop reading src at this index.
-    end_src_index: usize,
-    /// Source text to tokenize.
-    src: Lrc<String>,
-    override_span: Option<Span>,
-}
-
-impl<'a> StringReader<'a> {
-    pub fn new(sess: &'a ParseSess,
-               source_file: Lrc<syntax_pos::SourceFile>,
-               override_span: Option<Span>) -> Self {
-        if source_file.src.is_none() {
-            sess.span_diagnostic.bug(&format!("cannot lex `source_file` without source: {}",
-                                              source_file.name));
-        }
-
-        let src = (*source_file.src.as_ref().unwrap()).clone();
-
-        StringReader {
-            sess,
-            start_pos: source_file.start_pos,
-            pos: source_file.start_pos,
-            end_src_index: src.len(),
-            src,
-            override_span,
-        }
-    }
-
-    pub fn retokenize(sess: &'a ParseSess, mut span: Span) -> Self {
-        let begin = sess.source_map().lookup_byte_offset(span.lo());
-        let end = sess.source_map().lookup_byte_offset(span.hi());
-
-        // Make the range zero-length if the span is invalid.
-        if begin.sf.start_pos != end.sf.start_pos {
-            span = span.shrink_to_lo();
-        }
-
-        let mut sr = StringReader::new(sess, begin.sf, None);
-
-        // Seek the lexer to the right byte range.
-        sr.end_src_index = sr.src_index(span.hi());
-
-        sr
-    }
-
-
-    fn mk_sp(&self, lo: BytePos, hi: BytePos) -> Span {
-        self.override_span.unwrap_or_else(|| Span::with_root_ctxt(lo, hi))
-    }
-
-    /// Returns the next token, including trivia like whitespace or comments.
-    ///
-    /// `Err(())` means that some errors were encountered, which can be
-    /// retrieved using `buffer_fatal_errors`.
-    pub fn next_token(&mut self) -> Token {
-        let start_src_index = self.src_index(self.pos);
-        let text: &str = &self.src[start_src_index..self.end_src_index];
-
-        if text.is_empty() {
-            let span = self.mk_sp(self.pos, self.pos);
-            return Token::new(token::Eof, span);
-        }
-
-        {
-            let is_beginning_of_file = self.pos == self.start_pos;
-            if is_beginning_of_file {
-                if let Some(shebang_len) = rustc_lexer::strip_shebang(text) {
-                    let start = self.pos;
-                    self.pos = self.pos + BytePos::from_usize(shebang_len);
-
-                    let sym = self.symbol_from(start + BytePos::from_usize("#!".len()));
-                    let kind = token::Shebang(sym);
-
-                    let span = self.mk_sp(start, self.pos);
-                    return Token::new(kind, span);
-                }
-            }
-        }
-
-        let token = rustc_lexer::first_token(text);
-
-        let start = self.pos;
-        self.pos = self.pos + BytePos::from_usize(token.len);
-
-        debug!("try_next_token: {:?}({:?})", token.kind, self.str_from(start));
-
-        // This could use `?`, but that makes code significantly (10-20%) slower.
-        // https://github.com/rust-lang/rust/issues/37939
-        let kind = self.cook_lexer_token(token.kind, start);
-
-        let span = self.mk_sp(start, self.pos);
-        Token::new(kind, span)
-    }
-
-    /// Report a fatal lexical error with a given span.
-    fn fatal_span(&self, sp: Span, m: &str) -> FatalError {
-        self.sess.span_diagnostic.span_fatal(sp, m)
-    }
-
-    /// Report a lexical error with a given span.
-    fn err_span(&self, sp: Span, m: &str) {
-        self.sess.span_diagnostic.struct_span_err(sp, m).emit();
-    }
-
-
-    /// Report a fatal error spanning [`from_pos`, `to_pos`).
-    fn fatal_span_(&self, from_pos: BytePos, to_pos: BytePos, m: &str) -> FatalError {
-        self.fatal_span(self.mk_sp(from_pos, to_pos), m)
-    }
-
-    /// Report a lexical error spanning [`from_pos`, `to_pos`).
-    fn err_span_(&self, from_pos: BytePos, to_pos: BytePos, m: &str) {
-        self.err_span(self.mk_sp(from_pos, to_pos), m)
-    }
-
-    fn struct_span_fatal(&self, from_pos: BytePos, to_pos: BytePos, m: &str)
-        -> DiagnosticBuilder<'a>
-    {
-        self.sess.span_diagnostic.struct_span_fatal(self.mk_sp(from_pos, to_pos), m)
-    }
-
-    fn struct_fatal_span_char(&self, from_pos: BytePos, to_pos: BytePos, m: &str, c: char)
-        -> DiagnosticBuilder<'a>
-    {
-        let mut m = m.to_string();
-        m.push_str(": ");
-        push_escaped_char(&mut m, c);
-
-        self.sess.span_diagnostic.struct_span_fatal(self.mk_sp(from_pos, to_pos), &m[..])
-    }
-
-    /// Turns simple `rustc_lexer::TokenKind` enum into a rich
-    /// `libsyntax::TokenKind`. This turns strings into interned
-    /// symbols and runs additional validation.
-    fn cook_lexer_token(
-        &self,
-        token: rustc_lexer::TokenKind,
-        start: BytePos,
-    ) -> TokenKind {
-        match token {
-            rustc_lexer::TokenKind::LineComment => {
-                let string = self.str_from(start);
-                // comments with only more "/"s are not doc comments
-                let tok = if comments::is_line_doc_comment(string) {
-                    self.forbid_bare_cr(start, string, "bare CR not allowed in doc-comment");
-                    token::DocComment(Symbol::intern(string))
-                } else {
-                    token::Comment
-                };
-
-                tok
-            }
-            rustc_lexer::TokenKind::BlockComment { terminated } => {
-                let string = self.str_from(start);
-                // block comments starting with "/**" or "/*!" are doc-comments
-                // but comments with only "*"s between two "/"s are not
-                let is_doc_comment = comments::is_block_doc_comment(string);
-
-                if !terminated {
-                    let msg = if is_doc_comment {
-                        "unterminated block doc-comment"
-                    } else {
-                        "unterminated block comment"
-                    };
-                    let last_bpos = self.pos;
-                    self.fatal_span_(start, last_bpos, msg).raise();
-                }
-
-                let tok = if is_doc_comment {
-                    self.forbid_bare_cr(start,
-                                        string,
-                                        "bare CR not allowed in block doc-comment");
-                    token::DocComment(Symbol::intern(string))
-                } else {
-                    token::Comment
-                };
-
-                tok
-            }
-            rustc_lexer::TokenKind::Whitespace => token::Whitespace,
-            rustc_lexer::TokenKind::Ident | rustc_lexer::TokenKind::RawIdent => {
-                let is_raw_ident = token == rustc_lexer::TokenKind::RawIdent;
-                let mut ident_start = start;
-                if is_raw_ident {
-                    ident_start = ident_start + BytePos(2);
-                }
-                // FIXME: perform NFKC normalization here. (Issue #2253)
-                let sym = self.symbol_from(ident_start);
-                if is_raw_ident {
-                    let span = self.mk_sp(start, self.pos);
-                    if !sym.can_be_raw() {
-                        self.err_span(span, &format!("`{}` cannot be a raw identifier", sym));
-                    }
-                    self.sess.raw_identifier_spans.borrow_mut().push(span);
-                }
-                token::Ident(sym, is_raw_ident)
-            }
-            rustc_lexer::TokenKind::Literal { kind, suffix_start } => {
-                let suffix_start = start + BytePos(suffix_start as u32);
-                let (kind, symbol) = self.cook_lexer_literal(start, suffix_start, kind);
-                let suffix = if suffix_start < self.pos {
-                    let string = self.str_from(suffix_start);
-                    if string == "_" {
-                        self.sess.span_diagnostic
-                            .struct_span_warn(self.mk_sp(suffix_start, self.pos),
-                                              "underscore literal suffix is not allowed")
-                            .warn("this was previously accepted by the compiler but is \
-                                   being phased out; it will become a hard error in \
-                                   a future release!")
-                            .note("for more information, see issue #42326 \
-                                   <https://github.com/rust-lang/rust/issues/42326>")
-                            .emit();
-                        None
-                    } else {
-                        Some(Symbol::intern(string))
-                    }
-                } else {
-                    None
-                };
-                token::Literal(token::Lit { kind, symbol, suffix })
-            }
-            rustc_lexer::TokenKind::Lifetime { starts_with_number } => {
-                // Include the leading `'` in the real identifier, for macro
-                // expansion purposes. See #12512 for the gory details of why
-                // this is necessary.
-                let lifetime_name = self.str_from(start);
-                if starts_with_number {
-                    self.err_span_(
-                        start,
-                        self.pos,
-                        "lifetimes cannot start with a number",
-                    );
-                }
-                let ident = Symbol::intern(lifetime_name);
-                token::Lifetime(ident)
-            }
-            rustc_lexer::TokenKind::Semi => token::Semi,
-            rustc_lexer::TokenKind::Comma => token::Comma,
-            rustc_lexer::TokenKind::Dot => token::Dot,
-            rustc_lexer::TokenKind::OpenParen => token::OpenDelim(token::Paren),
-            rustc_lexer::TokenKind::CloseParen => token::CloseDelim(token::Paren),
-            rustc_lexer::TokenKind::OpenBrace => token::OpenDelim(token::Brace),
-            rustc_lexer::TokenKind::CloseBrace => token::CloseDelim(token::Brace),
-            rustc_lexer::TokenKind::OpenBracket => token::OpenDelim(token::Bracket),
-            rustc_lexer::TokenKind::CloseBracket => token::CloseDelim(token::Bracket),
-            rustc_lexer::TokenKind::At => token::At,
-            rustc_lexer::TokenKind::Pound => token::Pound,
-            rustc_lexer::TokenKind::Tilde => token::Tilde,
-            rustc_lexer::TokenKind::Question => token::Question,
-            rustc_lexer::TokenKind::Colon => token::Colon,
-            rustc_lexer::TokenKind::Dollar => token::Dollar,
-            rustc_lexer::TokenKind::Eq => token::Eq,
-            rustc_lexer::TokenKind::Not => token::Not,
-            rustc_lexer::TokenKind::Lt => token::Lt,
-            rustc_lexer::TokenKind::Gt => token::Gt,
-            rustc_lexer::TokenKind::Minus => token::BinOp(token::Minus),
-            rustc_lexer::TokenKind::And => token::BinOp(token::And),
-            rustc_lexer::TokenKind::Or => token::BinOp(token::Or),
-            rustc_lexer::TokenKind::Plus => token::BinOp(token::Plus),
-            rustc_lexer::TokenKind::Star => token::BinOp(token::Star),
-            rustc_lexer::TokenKind::Slash => token::BinOp(token::Slash),
-            rustc_lexer::TokenKind::Caret => token::BinOp(token::Caret),
-            rustc_lexer::TokenKind::Percent => token::BinOp(token::Percent),
-
-            rustc_lexer::TokenKind::Unknown => {
-                let c = self.str_from(start).chars().next().unwrap();
-                let mut err = self.struct_fatal_span_char(start,
-                                                          self.pos,
-                                                          "unknown start of token",
-                                                          c);
-                // FIXME: the lexer could be used to turn the ASCII version of unicode homoglyphs,
-                // instead of keeping a table in `check_for_substitution`into the token. Ideally,
-                // this should be inside `rustc_lexer`. However, we should first remove compound
-                // tokens like `<<` from `rustc_lexer`, and then add fancier error recovery to it,
-                // as there will be less overall work to do this way.
-                let token = unicode_chars::check_for_substitution(self, start, c, &mut err)
-                    .unwrap_or_else(|| token::Unknown(self.symbol_from(start)));
-                err.emit();
-                token
-            }
-        }
-    }
-
-    fn cook_lexer_literal(
-        &self,
-        start: BytePos,
-        suffix_start: BytePos,
-        kind: rustc_lexer::LiteralKind
-    ) -> (token::LitKind, Symbol) {
-        match kind {
-            rustc_lexer::LiteralKind::Char { terminated } => {
-                if !terminated {
-                    self.fatal_span_(start, suffix_start,
-                                     "unterminated character literal".into())
-                        .raise()
-                }
-                let content_start = start + BytePos(1);
-                let content_end = suffix_start - BytePos(1);
-                self.validate_char_escape(content_start, content_end);
-                let id = self.symbol_from_to(content_start, content_end);
-                (token::Char, id)
-            },
-            rustc_lexer::LiteralKind::Byte { terminated } => {
-                if !terminated {
-                    self.fatal_span_(start + BytePos(1), suffix_start,
-                                     "unterminated byte constant".into())
-                        .raise()
-                }
-                let content_start = start + BytePos(2);
-                let content_end = suffix_start - BytePos(1);
-                self.validate_byte_escape(content_start, content_end);
-                let id = self.symbol_from_to(content_start, content_end);
-                (token::Byte, id)
-            },
-            rustc_lexer::LiteralKind::Str { terminated } => {
-                if !terminated {
-                    self.fatal_span_(start, suffix_start,
-                                     "unterminated double quote string".into())
-                        .raise()
-                }
-                let content_start = start + BytePos(1);
-                let content_end = suffix_start - BytePos(1);
-                self.validate_str_escape(content_start, content_end);
-                let id = self.symbol_from_to(content_start, content_end);
-                (token::Str, id)
-            }
-            rustc_lexer::LiteralKind::ByteStr { terminated } => {
-                if !terminated {
-                    self.fatal_span_(start + BytePos(1), suffix_start,
-                                     "unterminated double quote byte string".into())
-                        .raise()
-                }
-                let content_start = start + BytePos(2);
-                let content_end = suffix_start - BytePos(1);
-                self.validate_byte_str_escape(content_start, content_end);
-                let id = self.symbol_from_to(content_start, content_end);
-                (token::ByteStr, id)
-            }
-            rustc_lexer::LiteralKind::RawStr { n_hashes, started, terminated } => {
-                if !started {
-                    self.report_non_started_raw_string(start);
-                }
-                if !terminated {
-                    self.report_unterminated_raw_string(start, n_hashes)
-                }
-                let n_hashes: u16 = self.restrict_n_hashes(start, n_hashes);
-                let n = u32::from(n_hashes);
-                let content_start = start + BytePos(2 + n);
-                let content_end = suffix_start - BytePos(1 + n);
-                self.validate_raw_str_escape(content_start, content_end);
-                let id = self.symbol_from_to(content_start, content_end);
-                (token::StrRaw(n_hashes), id)
-            }
-            rustc_lexer::LiteralKind::RawByteStr { n_hashes, started, terminated } => {
-                if !started {
-                    self.report_non_started_raw_string(start);
-                }
-                if !terminated {
-                    self.report_unterminated_raw_string(start, n_hashes)
-                }
-                let n_hashes: u16 = self.restrict_n_hashes(start, n_hashes);
-                let n = u32::from(n_hashes);
-                let content_start = start + BytePos(3 + n);
-                let content_end = suffix_start - BytePos(1 + n);
-                self.validate_raw_byte_str_escape(content_start, content_end);
-                let id = self.symbol_from_to(content_start, content_end);
-                (token::ByteStrRaw(n_hashes), id)
-            }
-            rustc_lexer::LiteralKind::Int { base, empty_int } => {
-                if empty_int {
-                    self.err_span_(start, suffix_start, "no valid digits found for number");
-                    (token::Integer, sym::integer(0))
-                } else {
-                    self.validate_int_literal(base, start, suffix_start);
-                    (token::Integer, self.symbol_from_to(start, suffix_start))
-                }
-            },
-            rustc_lexer::LiteralKind::Float { base, empty_exponent } => {
-                if empty_exponent {
-                    let mut err = self.struct_span_fatal(
-                        start, self.pos,
-                        "expected at least one digit in exponent"
-                    );
-                    err.emit();
-                }
-
-                match base {
-                    Base::Hexadecimal => {
-                        self.err_span_(start, suffix_start,
-                                       "hexadecimal float literal is not supported")
-                    }
-                    Base::Octal => {
-                        self.err_span_(start, suffix_start,
-                                       "octal float literal is not supported")
-                    }
-                    Base::Binary => {
-                        self.err_span_(start, suffix_start,
-                                       "binary float literal is not supported")
-                    }
-                    _ => ()
-                }
-
-                let id = self.symbol_from_to(start, suffix_start);
-                (token::Float, id)
-            },
-        }
-    }
-
-    #[inline]
-    fn src_index(&self, pos: BytePos) -> usize {
-        (pos - self.start_pos).to_usize()
-    }
-
-    /// Slice of the source text from `start` up to but excluding `self.pos`,
-    /// meaning the slice does not include the character `self.ch`.
-    fn str_from(&self, start: BytePos) -> &str
-    {
-        self.str_from_to(start, self.pos)
-    }
-
-    /// Creates a Symbol from a given offset to the current offset.
-    fn symbol_from(&self, start: BytePos) -> Symbol {
-        debug!("taking an ident from {:?} to {:?}", start, self.pos);
-        Symbol::intern(self.str_from(start))
-    }
-
-    /// As symbol_from, with an explicit endpoint.
-    fn symbol_from_to(&self, start: BytePos, end: BytePos) -> Symbol {
-        debug!("taking an ident from {:?} to {:?}", start, end);
-        Symbol::intern(self.str_from_to(start, end))
-    }
-
-    /// Slice of the source text spanning from `start` up to but excluding `end`.
-    fn str_from_to(&self, start: BytePos, end: BytePos) -> &str
-    {
-        &self.src[self.src_index(start)..self.src_index(end)]
-    }
-
-    fn forbid_bare_cr(&self, start: BytePos, s: &str, errmsg: &str) {
-        let mut idx = 0;
-        loop {
-            idx = match s[idx..].find('\r') {
-                None => break,
-                Some(it) => idx + it + 1
-            };
-            self.err_span_(start + BytePos(idx as u32 - 1),
-                           start + BytePos(idx as u32),
-                           errmsg);
-        }
-    }
-
-    fn report_non_started_raw_string(&self, start: BytePos) -> ! {
-        let bad_char = self.str_from(start).chars().last().unwrap();
-        self
-            .struct_fatal_span_char(
-                start,
-                self.pos,
-                "found invalid character; only `#` is allowed \
-                 in raw string delimitation",
-                bad_char,
-            )
-            .emit();
-        FatalError.raise()
-    }
-
-    fn report_unterminated_raw_string(&self, start: BytePos, n_hashes: usize) -> ! {
-        let mut err = self.struct_span_fatal(
-            start, start,
-            "unterminated raw string",
-        );
-        err.span_label(
-            self.mk_sp(start, start),
-            "unterminated raw string",
-        );
-
-        if n_hashes > 0 {
-            err.note(&format!("this raw string should be terminated with `\"{}`",
-                                "#".repeat(n_hashes as usize)));
-        }
-
-        err.emit();
-        FatalError.raise()
-    }
-
-    fn restrict_n_hashes(&self, start: BytePos, n_hashes: usize) -> u16 {
-        match n_hashes.try_into() {
-            Ok(n_hashes) => n_hashes,
-            Err(_) => {
-                self.fatal_span_(start,
-                                 self.pos,
-                                 "too many `#` symbols: raw strings may be \
-                                  delimited by up to 65535 `#` symbols").raise();
-            }
-        }
-    }
-
-    fn validate_char_escape(&self, content_start: BytePos, content_end: BytePos) {
-        let lit = self.str_from_to(content_start, content_end);
-        if let Err((off, err)) = unescape::unescape_char(lit) {
-            emit_unescape_error(
-                &self.sess.span_diagnostic,
-                lit,
-                self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
-                unescape::Mode::Char,
-                0..off,
-                err,
-            )
-        }
-    }
-
-    fn validate_byte_escape(&self, content_start: BytePos, content_end: BytePos) {
-        let lit = self.str_from_to(content_start, content_end);
-        if let Err((off, err)) = unescape::unescape_byte(lit) {
-            emit_unescape_error(
-                &self.sess.span_diagnostic,
-                lit,
-                self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
-                unescape::Mode::Byte,
-                0..off,
-                err,
-            )
-        }
-    }
-
-    fn validate_str_escape(&self, content_start: BytePos, content_end: BytePos) {
-        let lit = self.str_from_to(content_start, content_end);
-        unescape::unescape_str(lit, &mut |range, c| {
-            if let Err(err) = c {
-                emit_unescape_error(
-                    &self.sess.span_diagnostic,
-                    lit,
-                    self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
-                    unescape::Mode::Str,
-                    range,
-                    err,
-                )
-            }
-        })
-    }
-
-    fn validate_raw_str_escape(&self, content_start: BytePos, content_end: BytePos) {
-        let lit = self.str_from_to(content_start, content_end);
-        unescape::unescape_raw_str(lit, &mut |range, c| {
-            if let Err(err) = c {
-                emit_unescape_error(
-                    &self.sess.span_diagnostic,
-                    lit,
-                    self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
-                    unescape::Mode::Str,
-                    range,
-                    err,
-                )
-            }
-        })
-    }
-
-    fn validate_raw_byte_str_escape(&self, content_start: BytePos, content_end: BytePos) {
-        let lit = self.str_from_to(content_start, content_end);
-        unescape::unescape_raw_byte_str(lit, &mut |range, c| {
-            if let Err(err) = c {
-                emit_unescape_error(
-                    &self.sess.span_diagnostic,
-                    lit,
-                    self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
-                    unescape::Mode::ByteStr,
-                    range,
-                    err,
-                )
-            }
-        })
-    }
-
-    fn validate_byte_str_escape(&self, content_start: BytePos, content_end: BytePos) {
-        let lit = self.str_from_to(content_start, content_end);
-        unescape::unescape_byte_str(lit, &mut |range, c| {
-            if let Err(err) = c {
-                emit_unescape_error(
-                    &self.sess.span_diagnostic,
-                    lit,
-                    self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
-                    unescape::Mode::ByteStr,
-                    range,
-                    err,
-                )
-            }
-        })
-    }
-
-    fn validate_int_literal(&self, base: Base, content_start: BytePos, content_end: BytePos) {
-        let base = match base {
-            Base::Binary => 2,
-            Base::Octal => 8,
-            _ => return,
-        };
-        let s = self.str_from_to(content_start + BytePos(2), content_end);
-        for (idx, c) in s.char_indices() {
-            let idx = idx as u32;
-            if c != '_' && c.to_digit(base).is_none() {
-                let lo = content_start + BytePos(2 + idx);
-                let hi = content_start + BytePos(2 + idx + c.len_utf8() as u32);
-                self.err_span_(lo, hi,
-                               &format!("invalid digit for a base {} literal", base));
-
-            }
-        }
-    }
-}
diff --git a/src/libsyntax/parse/lexer/tokentrees.rs b/src/libsyntax/parse/lexer/tokentrees.rs
deleted file mode 100644
index 2b056434d4d..00000000000
--- a/src/libsyntax/parse/lexer/tokentrees.rs
+++ /dev/null
@@ -1,280 +0,0 @@
-use rustc_data_structures::fx::FxHashMap;
-use syntax_pos::Span;
-
-use super::{StringReader, UnmatchedBrace};
-
-use crate::print::pprust::token_to_string;
-use crate::token::{self, Token};
-use crate::tokenstream::{DelimSpan, IsJoint::{self, *}, TokenStream, TokenTree, TreeAndJoint};
-
-use errors::PResult;
-
-impl<'a> StringReader<'a> {
-    crate fn into_token_trees(self) -> (PResult<'a, TokenStream>, Vec<UnmatchedBrace>) {
-        let mut tt_reader = TokenTreesReader {
-            string_reader: self,
-            token: Token::dummy(),
-            joint_to_prev: Joint,
-            open_braces: Vec::new(),
-            unmatched_braces: Vec::new(),
-            matching_delim_spans: Vec::new(),
-            last_unclosed_found_span: None,
-            last_delim_empty_block_spans: FxHashMap::default()
-        };
-        let res = tt_reader.parse_all_token_trees();
-        (res, tt_reader.unmatched_braces)
-    }
-}
-
-struct TokenTreesReader<'a> {
-    string_reader: StringReader<'a>,
-    token: Token,
-    joint_to_prev: IsJoint,
-    /// Stack of open delimiters and their spans. Used for error message.
-    open_braces: Vec<(token::DelimToken, Span)>,
-    unmatched_braces: Vec<UnmatchedBrace>,
-    /// The type and spans for all braces
-    ///
-    /// Used only for error recovery when arriving to EOF with mismatched braces.
-    matching_delim_spans: Vec<(token::DelimToken, Span, Span)>,
-    last_unclosed_found_span: Option<Span>,
-    last_delim_empty_block_spans: FxHashMap<token::DelimToken, Span>
-}
-
-impl<'a> TokenTreesReader<'a> {
-    // Parse a stream of tokens into a list of `TokenTree`s, up to an `Eof`.
-    fn parse_all_token_trees(&mut self) -> PResult<'a, TokenStream> {
-        let mut buf = TokenStreamBuilder::default();
-
-        self.real_token();
-        while self.token != token::Eof {
-            buf.push(self.parse_token_tree()?);
-        }
-
-        Ok(buf.into_token_stream())
-    }
-
-    // Parse a stream of tokens into a list of `TokenTree`s, up to a `CloseDelim`.
-    fn parse_token_trees_until_close_delim(&mut self) -> TokenStream {
-        let mut buf = TokenStreamBuilder::default();
-        loop {
-            if let token::CloseDelim(..) = self.token.kind {
-                return buf.into_token_stream();
-            }
-
-            match self.parse_token_tree() {
-                Ok(tree) => buf.push(tree),
-                Err(mut e) => {
-                    e.emit();
-                    return buf.into_token_stream();
-                }
-            }
-        }
-    }
-
-    fn parse_token_tree(&mut self) -> PResult<'a, TreeAndJoint> {
-        let sm = self.string_reader.sess.source_map();
-        match self.token.kind {
-            token::Eof => {
-                let msg = "this file contains an un-closed delimiter";
-                let mut err = self.string_reader.sess.span_diagnostic
-                    .struct_span_err(self.token.span, msg);
-                for &(_, sp) in &self.open_braces {
-                    err.span_label(sp, "un-closed delimiter");
-                    self.unmatched_braces.push(UnmatchedBrace {
-                        expected_delim: token::DelimToken::Brace,
-                        found_delim: None,
-                        found_span: self.token.span,
-                        unclosed_span: Some(sp),
-                        candidate_span: None,
-                    });
-                }
-
-                if let Some((delim, _)) = self.open_braces.last() {
-                    if let Some((_, open_sp, close_sp)) = self.matching_delim_spans.iter()
-                        .filter(|(d, open_sp, close_sp)| {
-                            if let Some(close_padding) = sm.span_to_margin(*close_sp) {
-                                if let Some(open_padding) = sm.span_to_margin(*open_sp) {
-                                    return delim == d && close_padding != open_padding;
-                                }
-                            }
-                            false
-                        }).next()  // these are in reverse order as they get inserted on close, but
-                    {              // we want the last open/first close
-                        err.span_label(
-                            *open_sp,
-                            "this delimiter might not be properly closed...",
-                        );
-                        err.span_label(
-                            *close_sp,
-                            "...as it matches this but it has different indentation",
-                        );
-                    }
-                }
-                Err(err)
-            },
-            token::OpenDelim(delim) => {
-                // The span for beginning of the delimited section
-                let pre_span = self.token.span;
-
-                // Parse the open delimiter.
-                self.open_braces.push((delim, self.token.span));
-                self.real_token();
-
-                // Parse the token trees within the delimiters.
-                // We stop at any delimiter so we can try to recover if the user
-                // uses an incorrect delimiter.
-                let tts = self.parse_token_trees_until_close_delim();
-
-                // Expand to cover the entire delimited token tree
-                let delim_span = DelimSpan::from_pair(pre_span, self.token.span);
-
-                match self.token.kind {
-                    // Correct delimiter.
-                    token::CloseDelim(d) if d == delim => {
-                        let (open_brace, open_brace_span) = self.open_braces.pop().unwrap();
-                        let close_brace_span = self.token.span;
-
-                        if tts.is_empty() {
-                            let empty_block_span = open_brace_span.to(close_brace_span);
-                            self.last_delim_empty_block_spans.insert(delim, empty_block_span);
-                        }
-
-                        if self.open_braces.len() == 0 {
-                            // Clear up these spans to avoid suggesting them as we've found
-                            // properly matched delimiters so far for an entire block.
-                            self.matching_delim_spans.clear();
-                        } else {
-                            self.matching_delim_spans.push(
-                                (open_brace, open_brace_span, close_brace_span),
-                            );
-                        }
-                        // Parse the close delimiter.
-                        self.real_token();
-                    }
-                    // Incorrect delimiter.
-                    token::CloseDelim(other) => {
-                        let mut unclosed_delimiter = None;
-                        let mut candidate = None;
-                        if self.last_unclosed_found_span != Some(self.token.span) {
-                            // do not complain about the same unclosed delimiter multiple times
-                            self.last_unclosed_found_span = Some(self.token.span);
-                            // This is a conservative error: only report the last unclosed
-                            // delimiter. The previous unclosed delimiters could actually be
-                            // closed! The parser just hasn't gotten to them yet.
-                            if let Some(&(_, sp)) = self.open_braces.last() {
-                                unclosed_delimiter = Some(sp);
-                            };
-                            if let Some(current_padding) = sm.span_to_margin(self.token.span) {
-                                for (brace, brace_span) in &self.open_braces {
-                                    if let Some(padding) = sm.span_to_margin(*brace_span) {
-                                        // high likelihood of these two corresponding
-                                        if current_padding == padding && brace == &other {
-                                            candidate = Some(*brace_span);
-                                        }
-                                    }
-                                }
-                            }
-                            let (tok, _) = self.open_braces.pop().unwrap();
-                            self.unmatched_braces.push(UnmatchedBrace {
-                                expected_delim: tok,
-                                found_delim: Some(other),
-                                found_span: self.token.span,
-                                unclosed_span: unclosed_delimiter,
-                                candidate_span: candidate,
-                            });
-                        } else {
-                            self.open_braces.pop();
-                        }
-
-                        // If the incorrect delimiter matches an earlier opening
-                        // delimiter, then don't consume it (it can be used to
-                        // close the earlier one). Otherwise, consume it.
-                        // E.g., we try to recover from:
-                        // fn foo() {
-                        //     bar(baz(
-                        // }  // Incorrect delimiter but matches the earlier `{`
-                        if !self.open_braces.iter().any(|&(b, _)| b == other) {
-                            self.real_token();
-                        }
-                    }
-                    token::Eof => {
-                        // Silently recover, the EOF token will be seen again
-                        // and an error emitted then. Thus we don't pop from
-                        // self.open_braces here.
-                    },
-                    _ => {}
-                }
-
-                Ok(TokenTree::Delimited(
-                    delim_span,
-                    delim,
-                    tts.into()
-                ).into())
-            },
-            token::CloseDelim(delim) => {
-                // An unexpected closing delimiter (i.e., there is no
-                // matching opening delimiter).
-                let token_str = token_to_string(&self.token);
-                let msg = format!("unexpected close delimiter: `{}`", token_str);
-                let mut err = self.string_reader.sess.span_diagnostic
-                    .struct_span_err(self.token.span, &msg);
-
-                if let Some(span) = self.last_delim_empty_block_spans.remove(&delim) {
-                    err.span_label(
-                        span,
-                        "this block is empty, you might have not meant to close it"
-                    );
-                }
-                err.span_label(self.token.span, "unexpected close delimiter");
-                Err(err)
-            },
-            _ => {
-                let tt = TokenTree::Token(self.token.take());
-                self.real_token();
-                let is_joint = self.joint_to_prev == Joint && self.token.is_op();
-                Ok((tt, if is_joint { Joint } else { NonJoint }))
-            }
-        }
-    }
-
-    fn real_token(&mut self) {
-        self.joint_to_prev = Joint;
-        loop {
-            let token = self.string_reader.next_token();
-            match token.kind {
-                token::Whitespace | token::Comment | token::Shebang(_) | token::Unknown(_) => {
-                    self.joint_to_prev = NonJoint;
-                }
-                _ => {
-                    self.token = token;
-                    return;
-                }
-            }
-        }
-    }
-}
-
-#[derive(Default)]
-struct TokenStreamBuilder {
-    buf: Vec<TreeAndJoint>,
-}
-
-impl TokenStreamBuilder {
-    fn push(&mut self, (tree, joint): TreeAndJoint) {
-        if let Some((TokenTree::Token(prev_token), Joint)) = self.buf.last() {
-            if let TokenTree::Token(token) = &tree {
-                if let Some(glued) = prev_token.glue(token) {
-                    self.buf.pop();
-                    self.buf.push((TokenTree::Token(glued), joint));
-                    return;
-                }
-            }
-        }
-        self.buf.push((tree, joint))
-    }
-
-    fn into_token_stream(self) -> TokenStream {
-        TokenStream::new(self.buf)
-    }
-}
diff --git a/src/libsyntax/parse/lexer/unescape_error_reporting.rs b/src/libsyntax/parse/lexer/unescape_error_reporting.rs
deleted file mode 100644
index 5565015179c..00000000000
--- a/src/libsyntax/parse/lexer/unescape_error_reporting.rs
+++ /dev/null
@@ -1,215 +0,0 @@
-//! Utilities for rendering escape sequence errors as diagnostics.
-
-use std::ops::Range;
-use std::iter::once;
-
-use rustc_lexer::unescape::{EscapeError, Mode};
-use syntax_pos::{Span, BytePos};
-
-use crate::errors::{Handler, Applicability};
-
-pub(crate) fn emit_unescape_error(
-    handler: &Handler,
-    // interior part of the literal, without quotes
-    lit: &str,
-    // full span of the literal, including quotes
-    span_with_quotes: Span,
-    mode: Mode,
-    // range of the error inside `lit`
-    range: Range<usize>,
-    error: EscapeError,
-) {
-    log::debug!("emit_unescape_error: {:?}, {:?}, {:?}, {:?}, {:?}",
-                lit, span_with_quotes, mode, range, error);
-    let span = {
-        let Range { start, end } = range;
-        let (start, end) = (start as u32, end as u32);
-        let lo = span_with_quotes.lo() + BytePos(start + 1);
-        let hi = lo + BytePos(end - start);
-            span_with_quotes
-            .with_lo(lo)
-            .with_hi(hi)
-    };
-    let last_char = || {
-        let c = lit[range.clone()].chars().rev().next().unwrap();
-        let span = span.with_lo(span.hi() - BytePos(c.len_utf8() as u32));
-        (c, span)
-    };
-    match error {
-        EscapeError::LoneSurrogateUnicodeEscape => {
-            handler.struct_span_err(span, "invalid unicode character escape")
-                .help("unicode escape must not be a surrogate")
-                .emit();
-        }
-        EscapeError::OutOfRangeUnicodeEscape => {
-            handler.struct_span_err(span, "invalid unicode character escape")
-                .help("unicode escape must be at most 10FFFF")
-                .emit();
-        }
-        EscapeError::MoreThanOneChar => {
-            let msg = if mode.is_bytes() {
-                "if you meant to write a byte string literal, use double quotes"
-            } else {
-                "if you meant to write a `str` literal, use double quotes"
-            };
-
-            handler
-                .struct_span_err(
-                    span_with_quotes,
-                    "character literal may only contain one codepoint",
-                )
-                .span_suggestion(
-                    span_with_quotes,
-                    msg,
-                    format!("\"{}\"", lit),
-                    Applicability::MachineApplicable,
-                ).emit()
-        }
-        EscapeError::EscapeOnlyChar => {
-            let (c, _span) = last_char();
-
-            let mut msg = if mode.is_bytes() {
-                "byte constant must be escaped: "
-            } else {
-                "character constant must be escaped: "
-            }.to_string();
-            push_escaped_char(&mut msg, c);
-
-            handler.span_err(span, msg.as_str())
-        }
-        EscapeError::BareCarriageReturn => {
-            let msg = if mode.in_double_quotes() {
-                "bare CR not allowed in string, use \\r instead"
-            } else {
-                "character constant must be escaped: \\r"
-            };
-            handler.span_err(span, msg);
-        }
-        EscapeError::BareCarriageReturnInRawString => {
-            assert!(mode.in_double_quotes());
-            let msg = "bare CR not allowed in raw string";
-            handler.span_err(span, msg);
-        }
-        EscapeError::InvalidEscape => {
-            let (c, span) = last_char();
-
-            let label = if mode.is_bytes() {
-                "unknown byte escape"
-            } else {
-                "unknown character escape"
-            };
-            let mut msg = label.to_string();
-            msg.push_str(": ");
-            push_escaped_char(&mut msg, c);
-
-            let mut diag = handler.struct_span_err(span, msg.as_str());
-            diag.span_label(span, label);
-            if c == '{' || c == '}' && !mode.is_bytes() {
-                diag.help("if used in a formatting string, \
-                           curly braces are escaped with `{{` and `}}`");
-            } else if c == '\r' {
-                diag.help("this is an isolated carriage return; \
-                           consider checking your editor and version control settings");
-            }
-            diag.emit();
-        }
-        EscapeError::TooShortHexEscape => {
-            handler.span_err(span, "numeric character escape is too short")
-        }
-        EscapeError::InvalidCharInHexEscape | EscapeError::InvalidCharInUnicodeEscape => {
-            let (c, span) = last_char();
-
-            let mut msg = if error == EscapeError::InvalidCharInHexEscape {
-                "invalid character in numeric character escape: "
-            } else {
-                "invalid character in unicode escape: "
-            }.to_string();
-            push_escaped_char(&mut msg, c);
-
-            handler.span_err(span, msg.as_str())
-        }
-        EscapeError::NonAsciiCharInByte => {
-            assert!(mode.is_bytes());
-            let (_c, span) = last_char();
-            handler.span_err(span, "byte constant must be ASCII. \
-                                    Use a \\xHH escape for a non-ASCII byte")
-        }
-        EscapeError::NonAsciiCharInByteString => {
-            assert!(mode.is_bytes());
-            let (_c, span) = last_char();
-            handler.span_err(span, "raw byte string must be ASCII")
-        }
-        EscapeError::OutOfRangeHexEscape => {
-            handler.span_err(span, "this form of character escape may only be used \
-                                    with characters in the range [\\x00-\\x7f]")
-        }
-        EscapeError::LeadingUnderscoreUnicodeEscape => {
-            let (_c, span) = last_char();
-            handler.span_err(span, "invalid start of unicode escape")
-        }
-        EscapeError::OverlongUnicodeEscape => {
-            handler.span_err(span, "overlong unicode escape (must have at most 6 hex digits)")
-        }
-        EscapeError::UnclosedUnicodeEscape => {
-            handler.span_err(span, "unterminated unicode escape (needed a `}`)")
-        }
-        EscapeError::NoBraceInUnicodeEscape => {
-            let msg = "incorrect unicode escape sequence";
-            let mut diag = handler.struct_span_err(span, msg);
-
-            let mut suggestion = "\\u{".to_owned();
-            let mut suggestion_len = 0;
-            let (c, char_span) = last_char();
-            let chars = once(c).chain(lit[range.end..].chars());
-            for c in chars.take(6).take_while(|c| c.is_digit(16)) {
-                suggestion.push(c);
-                suggestion_len += c.len_utf8();
-            }
-
-            if suggestion_len > 0 {
-                suggestion.push('}');
-                let lo = char_span.lo();
-                let hi = lo + BytePos(suggestion_len as u32);
-                diag.span_suggestion(
-                    span.with_lo(lo).with_hi(hi),
-                    "format of unicode escape sequences uses braces",
-                    suggestion,
-                    Applicability::MaybeIncorrect,
-                );
-            } else {
-                diag.span_label(span, msg);
-                diag.help(
-                    "format of unicode escape sequences is `\\u{...}`",
-                );
-            }
-
-            diag.emit();
-        }
-        EscapeError::UnicodeEscapeInByte => {
-            handler.span_err(span, "unicode escape sequences cannot be used \
-                                    as a byte or in a byte string")
-        }
-        EscapeError::EmptyUnicodeEscape => {
-            handler.span_err(span, "empty unicode escape (must have at least 1 hex digit)")
-        }
-        EscapeError::ZeroChars => {
-            handler.span_err(span, "empty character literal")
-        }
-        EscapeError::LoneSlash => {
-            handler.span_err(span, "invalid trailing slash in literal")
-        }
-    }
-}
-
-/// Pushes a character to a message string for error reporting
-pub(crate) fn push_escaped_char(msg: &mut String, c: char) {
-    match c {
-        '\u{20}'..='\u{7e}' => {
-            // Don't escape \, ' or " for user-facing messages
-            msg.push(c);
-        }
-        _ => {
-            msg.extend(c.escape_default());
-        }
-    }
-}
diff --git a/src/libsyntax/parse/lexer/unicode_chars.rs b/src/libsyntax/parse/lexer/unicode_chars.rs
deleted file mode 100644
index 6eb995b61d3..00000000000
--- a/src/libsyntax/parse/lexer/unicode_chars.rs
+++ /dev/null
@@ -1,392 +0,0 @@
-// Characters and their corresponding confusables were collected from
-// http://www.unicode.org/Public/security/10.0.0/confusables.txt
-
-use super::StringReader;
-use errors::{Applicability, DiagnosticBuilder};
-use syntax_pos::{BytePos, Pos, Span, symbol::kw};
-use crate::token;
-
-#[rustfmt::skip] // for line breaks
-const UNICODE_ARRAY: &[(char, &str, char)] = &[
-    ('
', "Line Separator", ' '),
-    ('
', "Paragraph Separator", ' '),
-    (' ', "Ogham Space mark", ' '),
-    (' ', "En Quad", ' '),
-    (' ', "Em Quad", ' '),
-    (' ', "En Space", ' '),
-    (' ', "Em Space", ' '),
-    (' ', "Three-Per-Em Space", ' '),
-    (' ', "Four-Per-Em Space", ' '),
-    (' ', "Six-Per-Em Space", ' '),
-    (' ', "Punctuation Space", ' '),
-    (' ', "Thin Space", ' '),
-    (' ', "Hair Space", ' '),
-    (' ', "Medium Mathematical Space", ' '),
-    (' ', "No-Break Space", ' '),
-    (' ', "Figure Space", ' '),
-    (' ', "Narrow No-Break Space", ' '),
-    ('　', "Ideographic Space", ' '),
-
-    ('ߺ', "Nko Lajanyalan", '_'),
-    ('﹍', "Dashed Low Line", '_'),
-    ('﹎', "Centreline Low Line", '_'),
-    ('﹏', "Wavy Low Line", '_'),
-    ('＿', "Fullwidth Low Line", '_'),
-
-    ('‐', "Hyphen", '-'),
-    ('‑', "Non-Breaking Hyphen", '-'),
-    ('‒', "Figure Dash", '-'),
-    ('–', "En Dash", '-'),
-    ('—', "Em Dash", '-'),
-    ('﹘', "Small Em Dash", '-'),
-    ('۔', "Arabic Full Stop", '-'),
-    ('⁃', "Hyphen Bullet", '-'),
-    ('˗', "Modifier Letter Minus Sign", '-'),
-    ('−', "Minus Sign", '-'),
-    ('➖', "Heavy Minus Sign", '-'),
-    ('Ⲻ', "Coptic Letter Dialect-P Ni", '-'),
-    ('ー', "Katakana-Hiragana Prolonged Sound Mark", '-'),
-    ('－', "Fullwidth Hyphen-Minus", '-'),
-    ('―', "Horizontal Bar", '-'),
-    ('─', "Box Drawings Light Horizontal", '-'),
-    ('━', "Box Drawings Heavy Horizontal", '-'),
-    ('㇐', "CJK Stroke H", '-'),
-    ('ꟷ', "Latin Epigraphic Letter Sideways I", '-'),
-    ('ᅳ', "Hangul Jungseong Eu", '-'),
-    ('ㅡ', "Hangul Letter Eu", '-'),
-    ('一', "CJK Unified Ideograph-4E00", '-'),
-    ('⼀', "Kangxi Radical One", '-'),
-
-    ('؍', "Arabic Date Separator", ','),
-    ('٫', "Arabic Decimal Separator", ','),
-    ('‚', "Single Low-9 Quotation Mark", ','),
-    ('¸', "Cedilla", ','),
-    ('ꓹ', "Lisu Letter Tone Na Po", ','),
-    ('，', "Fullwidth Comma", ','),
-
-    (';', "Greek Question Mark", ';'),
-    ('；', "Fullwidth Semicolon", ';'),
-    ('︔', "Presentation Form For Vertical Semicolon", ';'),
-
-    ('ः', "Devanagari Sign Visarga", ':'),
-    ('ઃ', "Gujarati Sign Visarga", ':'),
-    ('：', "Fullwidth Colon", ':'),
-    ('։', "Armenian Full Stop", ':'),
-    ('܃', "Syriac Supralinear Colon", ':'),
-    ('܄', "Syriac Sublinear Colon", ':'),
-    ('᛬', "Runic Multiple Punctuation", ':'),
-    ('︰', "Presentation Form For Vertical Two Dot Leader", ':'),
-    ('᠃', "Mongolian Full Stop", ':'),
-    ('᠉', "Mongolian Manchu Full Stop", ':'),
-    ('⁚', "Two Dot Punctuation", ':'),
-    ('׃', "Hebrew Punctuation Sof Pasuq", ':'),
-    ('˸', "Modifier Letter Raised Colon", ':'),
-    ('꞉', "Modifier Letter Colon", ':'),
-    ('∶', "Ratio", ':'),
-    ('ː', "Modifier Letter Triangular Colon", ':'),
-    ('ꓽ', "Lisu Letter Tone Mya Jeu", ':'),
-    ('︓', "Presentation Form For Vertical Colon", ':'),
-
-    ('！', "Fullwidth Exclamation Mark", '!'),
-    ('ǃ', "Latin Letter Retroflex Click", '!'),
-    ('ⵑ', "Tifinagh Letter Tuareg Yang", '!'),
-    ('︕', "Presentation Form For Vertical Exclamation Mark", '!'),
-
-    ('ʔ', "Latin Letter Glottal Stop", '?'),
-    ('Ɂ', "Latin Capital Letter Glottal Stop", '?'),
-    ('ॽ', "Devanagari Letter Glottal Stop", '?'),
-    ('Ꭾ', "Cherokee Letter He", '?'),
-    ('ꛫ', "Bamum Letter Ntuu", '?'),
-    ('？', "Fullwidth Question Mark", '?'),
-    ('︖', "Presentation Form For Vertical Question Mark", '?'),
-
-    ('𝅭', "Musical Symbol Combining Augmentation Dot", '.'),
-    ('․', "One Dot Leader", '.'),
-    ('܁', "Syriac Supralinear Full Stop", '.'),
-    ('܂', "Syriac Sublinear Full Stop", '.'),
-    ('꘎', "Vai Full Stop", '.'),
-    ('𐩐', "Kharoshthi Punctuation Dot", '.'),
-    ('٠', "Arabic-Indic Digit Zero", '.'),
-    ('۰', "Extended Arabic-Indic Digit Zero", '.'),
-    ('ꓸ', "Lisu Letter Tone Mya Ti", '.'),
-    ('·', "Middle Dot", '.'),
-    ('・', "Katakana Middle Dot", '.'),
-    ('･', "Halfwidth Katakana Middle Dot", '.'),
-    ('᛫', "Runic Single Punctuation", '.'),
-    ('·', "Greek Ano Teleia", '.'),
-    ('⸱', "Word Separator Middle Dot", '.'),
-    ('𐄁', "Aegean Word Separator Dot", '.'),
-    ('•', "Bullet", '.'),
-    ('‧', "Hyphenation Point", '.'),
-    ('∙', "Bullet Operator", '.'),
-    ('⋅', "Dot Operator", '.'),
-    ('ꞏ', "Latin Letter Sinological Dot", '.'),
-    ('ᐧ', "Canadian Syllabics Final Middle Dot", '.'),
-    ('ᐧ', "Canadian Syllabics Final Middle Dot", '.'),
-    ('．', "Fullwidth Full Stop", '.'),
-    ('。', "Ideographic Full Stop", '.'),
-    ('︒', "Presentation Form For Vertical Ideographic Full Stop", '.'),
-
-    ('՝', "Armenian Comma", '\''),
-    ('＇', "Fullwidth Apostrophe", '\''),
-    ('‘', "Left Single Quotation Mark", '\''),
-    ('’', "Right Single Quotation Mark", '\''),
-    ('‛', "Single High-Reversed-9 Quotation Mark", '\''),
-    ('′', "Prime", '\''),
-    ('‵', "Reversed Prime", '\''),
-    ('՚', "Armenian Apostrophe", '\''),
-    ('׳', "Hebrew Punctuation Geresh", '\''),
-    ('`', "Grave Accent", '\''),
-    ('`', "Greek Varia", '\''),
-    ('｀', "Fullwidth Grave Accent", '\''),
-    ('´', "Acute Accent", '\''),
-    ('΄', "Greek Tonos", '\''),
-    ('´', "Greek Oxia", '\''),
-    ('᾽', "Greek Koronis", '\''),
-    ('᾿', "Greek Psili", '\''),
-    ('῾', "Greek Dasia", '\''),
-    ('ʹ', "Modifier Letter Prime", '\''),
-    ('ʹ', "Greek Numeral Sign", '\''),
-    ('ˈ', "Modifier Letter Vertical Line", '\''),
-    ('ˊ', "Modifier Letter Acute Accent", '\''),
-    ('ˋ', "Modifier Letter Grave Accent", '\''),
-    ('˴', "Modifier Letter Middle Grave Accent", '\''),
-    ('ʻ', "Modifier Letter Turned Comma", '\''),
-    ('ʽ', "Modifier Letter Reversed Comma", '\''),
-    ('ʼ', "Modifier Letter Apostrophe", '\''),
-    ('ʾ', "Modifier Letter Right Half Ring", '\''),
-    ('ꞌ', "Latin Small Letter Saltillo", '\''),
-    ('י', "Hebrew Letter Yod", '\''),
-    ('ߴ', "Nko High Tone Apostrophe", '\''),
-    ('ߵ', "Nko Low Tone Apostrophe", '\''),
-    ('ᑊ', "Canadian Syllabics West-Cree P", '\''),
-    ('ᛌ', "Runic Letter Short-Twig-Sol S", '\''),
-    ('𖽑', "Miao Sign Aspiration", '\''),
-    ('𖽒', "Miao Sign Reformed Voicing", '\''),
-
-    ('᳓', "Vedic Sign Nihshvasa", '"'),
-    ('＂', "Fullwidth Quotation Mark", '"'),
-    ('“', "Left Double Quotation Mark", '"'),
-    ('”', "Right Double Quotation Mark", '"'),
-    ('‟', "Double High-Reversed-9 Quotation Mark", '"'),
-    ('″', "Double Prime", '"'),
-    ('‶', "Reversed Double Prime", '"'),
-    ('〃', "Ditto Mark", '"'),
-    ('״', "Hebrew Punctuation Gershayim", '"'),
-    ('˝', "Double Acute Accent", '"'),
-    ('ʺ', "Modifier Letter Double Prime", '"'),
-    ('˶', "Modifier Letter Middle Double Acute Accent", '"'),
-    ('˵', "Modifier Letter Middle Double Grave Accent", '"'),
-    ('ˮ', "Modifier Letter Double Apostrophe", '"'),
-    ('ײ', "Hebrew Ligature Yiddish Double Yod", '"'),
-    ('❞', "Heavy Double Comma Quotation Mark Ornament", '"'),
-    ('❝', "Heavy Double Turned Comma Quotation Mark Ornament", '"'),
-
-    ('（', "Fullwidth Left Parenthesis", '('),
-    ('❨', "Medium Left Parenthesis Ornament", '('),
-    ('﴾', "Ornate Left Parenthesis", '('),
-
-    ('）', "Fullwidth Right Parenthesis", ')'),
-    ('❩', "Medium Right Parenthesis Ornament", ')'),
-    ('﴿', "Ornate Right Parenthesis", ')'),
-
-    ('［', "Fullwidth Left Square Bracket", '['),
-    ('❲', "Light Left Tortoise Shell Bracket Ornament", '['),
-    ('「', "Left Corner Bracket", '['),
-    ('『', "Left White Corner Bracket", '['),
-    ('【', "Left Black Lenticular Bracket", '['),
-    ('〔', "Left Tortoise Shell Bracket", '['),
-    ('〖', "Left White Lenticular Bracket", '['),
-    ('〘', "Left White Tortoise Shell Bracket", '['),
-    ('〚', "Left White Square Bracket", '['),
-
-    ('］', "Fullwidth Right Square Bracket", ']'),
-    ('❳', "Light Right Tortoise Shell Bracket Ornament", ']'),
-    ('」', "Right Corner Bracket", ']'),
-    ('』', "Right White Corner Bracket", ']'),
-    ('】', "Right Black Lenticular Bracket", ']'),
-    ('〕', "Right Tortoise Shell Bracket", ']'),
-    ('〗', "Right White Lenticular Bracket", ']'),
-    ('〙', "Right White Tortoise Shell Bracket", ']'),
-    ('〛', "Right White Square Bracket", ']'),
-
-    ('❴', "Medium Left Curly Bracket Ornament", '{'),
-    ('𝄔', "Musical Symbol Brace", '{'),
-    ('｛', "Fullwidth Left Curly Bracket", '{'),
-
-    ('❵', "Medium Right Curly Bracket Ornament", '}'),
-    ('｝', "Fullwidth Right Curly Bracket", '}'),
-
-    ('⁎', "Low Asterisk", '*'),
-    ('٭', "Arabic Five Pointed Star", '*'),
-    ('∗', "Asterisk Operator", '*'),
-    ('𐌟', "Old Italic Letter Ess", '*'),
-    ('＊', "Fullwidth Asterisk", '*'),
-
-    ('᜵', "Philippine Single Punctuation", '/'),
-    ('⁁', "Caret Insertion Point", '/'),
-    ('∕', "Division Slash", '/'),
-    ('⁄', "Fraction Slash", '/'),
-    ('╱', "Box Drawings Light Diagonal Upper Right To Lower Left", '/'),
-    ('⟋', "Mathematical Rising Diagonal", '/'),
-    ('⧸', "Big Solidus", '/'),
-    ('𝈺', "Greek Instrumental Notation Symbol-47", '/'),
-    ('㇓', "CJK Stroke Sp", '/'),
-    ('〳', "Vertical Kana Repeat Mark Upper Half", '/'),
-    ('Ⳇ', "Coptic Capital Letter Old Coptic Esh", '/'),
-    ('ノ', "Katakana Letter No", '/'),
-    ('丿', "CJK Unified Ideograph-4E3F", '/'),
-    ('⼃', "Kangxi Radical Slash", '/'),
-    ('／', "Fullwidth Solidus", '/'),
-
-    ('＼', "Fullwidth Reverse Solidus", '\\'),
-    ('﹨', "Small Reverse Solidus", '\\'),
-    ('∖', "Set Minus", '\\'),
-    ('⟍', "Mathematical Falling Diagonal", '\\'),
-    ('⧵', "Reverse Solidus Operator", '\\'),
-    ('⧹', "Big Reverse Solidus", '\\'),
-    ('⧹', "Greek Vocal Notation Symbol-16", '\\'),
-    ('⧹', "Greek Instrumental Symbol-48", '\\'),
-    ('㇔', "CJK Stroke D", '\\'),
-    ('丶', "CJK Unified Ideograph-4E36", '\\'),
-    ('⼂', "Kangxi Radical Dot", '\\'),
-    ('、', "Ideographic Comma", '\\'),
-    ('ヽ', "Katakana Iteration Mark", '\\'),
-
-    ('ꝸ', "Latin Small Letter Um", '&'),
-    ('＆', "Fullwidth Ampersand", '&'),
-
-    ('᛭', "Runic Cross Punctuation", '+'),
-    ('➕', "Heavy Plus Sign", '+'),
-    ('𐊛', "Lycian Letter H", '+'),
-    ('﬩', "Hebrew Letter Alternative Plus Sign", '+'),
-    ('＋', "Fullwidth Plus Sign", '+'),
-
-    ('‹', "Single Left-Pointing Angle Quotation Mark", '<'),
-    ('❮', "Heavy Left-Pointing Angle Quotation Mark Ornament", '<'),
-    ('˂', "Modifier Letter Left Arrowhead", '<'),
-    ('𝈶', "Greek Instrumental Symbol-40", '<'),
-    ('ᐸ', "Canadian Syllabics Pa", '<'),
-    ('ᚲ', "Runic Letter Kauna", '<'),
-    ('❬', "Medium Left-Pointing Angle Bracket Ornament", '<'),
-    ('⟨', "Mathematical Left Angle Bracket", '<'),
-    ('〈', "Left-Pointing Angle Bracket", '<'),
-    ('〈', "Left Angle Bracket", '<'),
-    ('㇛', "CJK Stroke Pd", '<'),
-    ('く', "Hiragana Letter Ku", '<'),
-    ('𡿨', "CJK Unified Ideograph-21FE8", '<'),
-    ('《', "Left Double Angle Bracket", '<'),
-    ('＜', "Fullwidth Less-Than Sign", '<'),
-
-    ('᐀', "Canadian Syllabics Hyphen", '='),
-    ('⹀', "Double Hyphen", '='),
-    ('゠', "Katakana-Hiragana Double Hyphen", '='),
-    ('꓿', "Lisu Punctuation Full Stop", '='),
-    ('＝', "Fullwidth Equals Sign", '='),
-
-    ('›', "Single Right-Pointing Angle Quotation Mark", '>'),
-    ('❯', "Heavy Right-Pointing Angle Quotation Mark Ornament", '>'),
-    ('˃', "Modifier Letter Right Arrowhead", '>'),
-    ('𝈷', "Greek Instrumental Symbol-42", '>'),
-    ('ᐳ', "Canadian Syllabics Po", '>'),
-    ('𖼿', "Miao Letter Archaic Zza", '>'),
-    ('❭', "Medium Right-Pointing Angle Bracket Ornament", '>'),
-    ('⟩', "Mathematical Right Angle Bracket", '>'),
-    ('〉', "Right-Pointing Angle Bracket", '>'),
-    ('〉', "Right Angle Bracket", '>'),
-    ('》', "Right Double Angle Bracket", '>'),
-    ('＞', "Fullwidth Greater-Than Sign", '>'),
-];
-
-// FIXME: the lexer could be used to turn the ASCII version of unicode homoglyphs, instead of
-// keeping the substitution token in this table. Ideally, this should be inside `rustc_lexer`.
-// However, we should first remove compound tokens like `<<` from `rustc_lexer`, and then add
-// fancier error recovery to it, as there will be less overall work to do this way.
-const ASCII_ARRAY: &[(char, &str, Option<token::TokenKind>)] = &[
-    (' ', "Space", Some(token::Whitespace)),
-    ('_', "Underscore", Some(token::Ident(kw::Underscore, false))),
-    ('-', "Minus/Hyphen", Some(token::BinOp(token::Minus))),
-    (',', "Comma", Some(token::Comma)),
-    (';', "Semicolon", Some(token::Semi)),
-    (':', "Colon", Some(token::Colon)),
-    ('!', "Exclamation Mark", Some(token::Not)),
-    ('?', "Question Mark", Some(token::Question)),
-    ('.', "Period", Some(token::Dot)),
-    ('(', "Left Parenthesis", Some(token::OpenDelim(token::Paren))),
-    (')', "Right Parenthesis", Some(token::CloseDelim(token::Paren))),
-    ('[', "Left Square Bracket", Some(token::OpenDelim(token::Bracket))),
-    (']', "Right Square Bracket", Some(token::CloseDelim(token::Bracket))),
-    ('{', "Left Curly Brace", Some(token::OpenDelim(token::Brace))),
-    ('}', "Right Curly Brace", Some(token::CloseDelim(token::Brace))),
-    ('*', "Asterisk", Some(token::BinOp(token::Star))),
-    ('/', "Slash", Some(token::BinOp(token::Slash))),
-    ('\\', "Backslash", None),
-    ('&', "Ampersand", Some(token::BinOp(token::And))),
-    ('+', "Plus Sign", Some(token::BinOp(token::Plus))),
-    ('<', "Less-Than Sign", Some(token::Lt)),
-    ('=', "Equals Sign", Some(token::Eq)),
-    ('>', "Greater-Than Sign", Some(token::Gt)),
-    // FIXME: Literals are already lexed by this point, so we can't recover gracefully just by
-    // spitting the correct token out.
-    ('\'', "Single Quote", None),
-    ('"', "Quotation Mark", None),
-];
-
-crate fn check_for_substitution<'a>(
-    reader: &StringReader<'a>,
-    pos: BytePos,
-    ch: char,
-    err: &mut DiagnosticBuilder<'a>,
-) -> Option<token::TokenKind> {
-    let (u_name, ascii_char) = match UNICODE_ARRAY.iter().find(|&&(c, _, _)| c == ch) {
-        Some(&(_u_char, u_name, ascii_char)) => (u_name, ascii_char),
-        None => return None,
-    };
-
-    let span = Span::with_root_ctxt(pos, pos + Pos::from_usize(ch.len_utf8()));
-
-    let (ascii_name, token) = match ASCII_ARRAY.iter().find(|&&(c, _, _)| c == ascii_char) {
-        Some((_ascii_char, ascii_name, token)) => (ascii_name, token),
-        None => {
-            let msg = format!("substitution character not found for '{}'", ch);
-            reader.sess.span_diagnostic.span_bug_no_panic(span, &msg);
-            return None;
-        }
-    };
-
-    // special help suggestion for "directed" double quotes
-    if let Some(s) = peek_delimited(&reader.src[reader.src_index(pos)..], '“', '”') {
-        let msg = format!(
-            "Unicode characters '“' (Left Double Quotation Mark) and \
-             '”' (Right Double Quotation Mark) look like '{}' ({}), but are not",
-            ascii_char, ascii_name
-        );
-        err.span_suggestion(
-            Span::with_root_ctxt(
-                pos,
-                pos + Pos::from_usize('“'.len_utf8() + s.len() + '”'.len_utf8()),
-            ),
-            &msg,
-            format!("\"{}\"", s),
-            Applicability::MaybeIncorrect,
-        );
-    } else {
-        let msg = format!(
-            "Unicode character '{}' ({}) looks like '{}' ({}), but it is not",
-            ch, u_name, ascii_char, ascii_name
-        );
-        err.span_suggestion(span, &msg, ascii_char.to_string(), Applicability::MaybeIncorrect);
-    }
-    token.clone()
-}
-
-/// Extract string if found at current position with given delimiters
-fn peek_delimited(text: &str, from_ch: char, to_ch: char) -> Option<&str> {
-    let mut chars = text.chars();
-    let first_char = chars.next()?;
-    if first_char != from_ch {
-        return None;
-    }
-    let last_char_idx = chars.as_str().find(to_ch)?;
-    Some(&chars.as_str()[..last_char_idx])
-}
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
deleted file mode 100644
index af3f8ecb45a..00000000000
--- a/src/libsyntax/parse/mod.rs
+++ /dev/null
@@ -1,420 +0,0 @@
-//! The main parser interface.
-
-use crate::ast;
-use crate::parse::parser::{Parser, emit_unclosed_delims, make_unclosed_delims_error};
-use crate::token::{self, Nonterminal};
-use crate::tokenstream::{self, TokenStream, TokenTree};
-use crate::print::pprust;
-use crate::sess::ParseSess;
-
-use errors::{PResult, FatalError, Level, Diagnostic};
-use rustc_data_structures::sync::Lrc;
-use syntax_pos::{Span, SourceFile, FileName};
-
-use std::borrow::Cow;
-use std::path::Path;
-use std::str;
-
-use log::info;
-
-pub const MACRO_ARGUMENTS: Option<&'static str> = Some("macro arguments");
-
-#[macro_use]
-pub mod parser;
-pub mod lexer;
-pub mod validate_attr;
-
-#[derive(Clone)]
-pub struct Directory<'a> {
-    pub path: Cow<'a, Path>,
-    pub ownership: DirectoryOwnership,
-}
-
-#[derive(Copy, Clone)]
-pub enum DirectoryOwnership {
-    Owned {
-        // None if `mod.rs`, `Some("foo")` if we're in `foo.rs`.
-        relative: Option<ast::Ident>,
-    },
-    UnownedViaBlock,
-    UnownedViaMod,
-}
-
-// A bunch of utility functions of the form `parse_<thing>_from_<source>`
-// where <thing> includes crate, expr, item, stmt, tts, and one that
-// uses a HOF to parse anything, and <source> includes file and
-// `source_str`.
-
-/// A variant of 'panictry!' that works on a Vec<Diagnostic> instead of a single DiagnosticBuilder.
-macro_rules! panictry_buffer {
-    ($handler:expr, $e:expr) => ({
-        use std::result::Result::{Ok, Err};
-        use errors::FatalError;
-        match $e {
-            Ok(e) => e,
-            Err(errs) => {
-                for e in errs {
-                    $handler.emit_diagnostic(&e);
-                }
-                FatalError.raise()
-            }
-        }
-    })
-}
-
-pub fn parse_crate_from_file<'a>(input: &Path, sess: &'a ParseSess) -> PResult<'a, ast::Crate> {
-    let mut parser = new_parser_from_file(sess, input);
-    parser.parse_crate_mod()
-}
-
-pub fn parse_crate_attrs_from_file<'a>(input: &Path, sess: &'a ParseSess)
-                                       -> PResult<'a, Vec<ast::Attribute>> {
-    let mut parser = new_parser_from_file(sess, input);
-    parser.parse_inner_attributes()
-}
-
-pub fn parse_crate_from_source_str(name: FileName, source: String, sess: &ParseSess)
-                                       -> PResult<'_, ast::Crate> {
-    new_parser_from_source_str(sess, name, source).parse_crate_mod()
-}
-
-pub fn parse_crate_attrs_from_source_str(name: FileName, source: String, sess: &ParseSess)
-                                             -> PResult<'_, Vec<ast::Attribute>> {
-    new_parser_from_source_str(sess, name, source).parse_inner_attributes()
-}
-
-pub fn parse_stream_from_source_str(
-    name: FileName,
-    source: String,
-    sess: &ParseSess,
-    override_span: Option<Span>,
-) -> TokenStream {
-    let (stream, mut errors) = source_file_to_stream(
-        sess,
-        sess.source_map().new_source_file(name, source),
-        override_span,
-    );
-    emit_unclosed_delims(&mut errors, &sess);
-    stream
-}
-
-/// Creates a new parser from a source string.
-pub fn new_parser_from_source_str(sess: &ParseSess, name: FileName, source: String) -> Parser<'_> {
-    panictry_buffer!(&sess.span_diagnostic, maybe_new_parser_from_source_str(sess, name, source))
-}
-
-/// Creates a new parser from a source string. Returns any buffered errors from lexing the initial
-/// token stream.
-pub fn maybe_new_parser_from_source_str(sess: &ParseSess, name: FileName, source: String)
-    -> Result<Parser<'_>, Vec<Diagnostic>>
-{
-    let mut parser = maybe_source_file_to_parser(sess,
-                                                 sess.source_map().new_source_file(name, source))?;
-    parser.recurse_into_file_modules = false;
-    Ok(parser)
-}
-
-/// Creates a new parser, handling errors as appropriate if the file doesn't exist.
-pub fn new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path) -> Parser<'a> {
-    source_file_to_parser(sess, file_to_source_file(sess, path, None))
-}
-
-/// Creates a new parser, returning buffered diagnostics if the file doesn't exist,
-/// or from lexing the initial token stream.
-pub fn maybe_new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path)
-    -> Result<Parser<'a>, Vec<Diagnostic>> {
-    let file = try_file_to_source_file(sess, path, None).map_err(|db| vec![db])?;
-    maybe_source_file_to_parser(sess, file)
-}
-
-/// Given a session, a crate config, a path, and a span, add
-/// the file at the given path to the `source_map`, and returns a parser.
-/// On an error, uses the given span as the source of the problem.
-pub fn new_sub_parser_from_file<'a>(sess: &'a ParseSess,
-                                    path: &Path,
-                                    directory_ownership: DirectoryOwnership,
-                                    module_name: Option<String>,
-                                    sp: Span) -> Parser<'a> {
-    let mut p = source_file_to_parser(sess, file_to_source_file(sess, path, Some(sp)));
-    p.directory.ownership = directory_ownership;
-    p.root_module_name = module_name;
-    p
-}
-
-/// Given a `source_file` and config, returns a parser.
-fn source_file_to_parser(sess: &ParseSess, source_file: Lrc<SourceFile>) -> Parser<'_> {
-    panictry_buffer!(&sess.span_diagnostic,
-                     maybe_source_file_to_parser(sess, source_file))
-}
-
-/// Given a `source_file` and config, return a parser. Returns any buffered errors from lexing the
-/// initial token stream.
-fn maybe_source_file_to_parser(
-    sess: &ParseSess,
-    source_file: Lrc<SourceFile>,
-) -> Result<Parser<'_>, Vec<Diagnostic>> {
-    let end_pos = source_file.end_pos;
-    let (stream, unclosed_delims) = maybe_file_to_stream(sess, source_file, None)?;
-    let mut parser = stream_to_parser(sess, stream, None);
-    parser.unclosed_delims = unclosed_delims;
-    if parser.token == token::Eof && parser.token.span.is_dummy() {
-        parser.token.span = Span::new(end_pos, end_pos, parser.token.span.ctxt());
-    }
-
-    Ok(parser)
-}
-
-// Must preserve old name for now, because `quote!` from the *existing*
-// compiler expands into it.
-pub fn new_parser_from_tts(sess: &ParseSess, tts: Vec<TokenTree>) -> Parser<'_> {
-    stream_to_parser(sess, tts.into_iter().collect(), crate::MACRO_ARGUMENTS)
-}
-
-
-// Base abstractions
-
-/// Given a session and a path and an optional span (for error reporting),
-/// add the path to the session's source_map and return the new source_file or
-/// error when a file can't be read.
-fn try_file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>)
-                   -> Result<Lrc<SourceFile>, Diagnostic> {
-    sess.source_map().load_file(path)
-    .map_err(|e| {
-        let msg = format!("couldn't read {}: {}", path.display(), e);
-        let mut diag = Diagnostic::new(Level::Fatal, &msg);
-        if let Some(sp) = spanopt {
-            diag.set_span(sp);
-        }
-        diag
-    })
-}
-
-/// Given a session and a path and an optional span (for error reporting),
-/// adds the path to the session's `source_map` and returns the new `source_file`.
-fn file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>)
-                   -> Lrc<SourceFile> {
-    match try_file_to_source_file(sess, path, spanopt) {
-        Ok(source_file) => source_file,
-        Err(d) => {
-            sess.span_diagnostic.emit_diagnostic(&d);
-            FatalError.raise();
-        }
-    }
-}
-
-/// Given a `source_file`, produces a sequence of token trees.
-pub fn source_file_to_stream(
-    sess: &ParseSess,
-    source_file: Lrc<SourceFile>,
-    override_span: Option<Span>,
-) -> (TokenStream, Vec<lexer::UnmatchedBrace>) {
-    panictry_buffer!(&sess.span_diagnostic, maybe_file_to_stream(sess, source_file, override_span))
-}
-
-/// Given a source file, produces a sequence of token trees. Returns any buffered errors from
-/// parsing the token stream.
-pub fn maybe_file_to_stream(
-    sess: &ParseSess,
-    source_file: Lrc<SourceFile>,
-    override_span: Option<Span>,
-) -> Result<(TokenStream, Vec<lexer::UnmatchedBrace>), Vec<Diagnostic>> {
-    let srdr = lexer::StringReader::new(sess, source_file, override_span);
-    let (token_trees, unmatched_braces) = srdr.into_token_trees();
-
-    match token_trees {
-        Ok(stream) => Ok((stream, unmatched_braces)),
-        Err(err) => {
-            let mut buffer = Vec::with_capacity(1);
-            err.buffer(&mut buffer);
-            // Not using `emit_unclosed_delims` to use `db.buffer`
-            for unmatched in unmatched_braces {
-                if let Some(err) = make_unclosed_delims_error(unmatched, &sess) {
-                    err.buffer(&mut buffer);
-                }
-            }
-            Err(buffer)
-        }
-    }
-}
-
-/// Given a stream and the `ParseSess`, produces a parser.
-pub fn stream_to_parser<'a>(
-    sess: &'a ParseSess,
-    stream: TokenStream,
-    subparser_name: Option<&'static str>,
-) -> Parser<'a> {
-    Parser::new(sess, stream, None, true, false, subparser_name)
-}
-
-/// Given a stream, the `ParseSess` and the base directory, produces a parser.
-///
-/// Use this function when you are creating a parser from the token stream
-/// and also care about the current working directory of the parser (e.g.,
-/// you are trying to resolve modules defined inside a macro invocation).
-///
-/// # Note
-///
-/// The main usage of this function is outside of rustc, for those who uses
-/// libsyntax as a library. Please do not remove this function while refactoring
-/// just because it is not used in rustc codebase!
-pub fn stream_to_parser_with_base_dir<'a>(
-    sess: &'a ParseSess,
-    stream: TokenStream,
-    base_dir: Directory<'a>,
-) -> Parser<'a> {
-    Parser::new(sess, stream, Some(base_dir), true, false, None)
-}
-
-/// Runs the given subparser `f` on the tokens of the given `attr`'s item.
-pub fn parse_in_attr<'a, T>(
-    sess: &'a ParseSess,
-    attr: &ast::Attribute,
-    mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
-) -> PResult<'a, T> {
-    let mut parser = Parser::new(
-        sess,
-        attr.get_normal_item().tokens.clone(),
-        None,
-        false,
-        false,
-        Some("attribute"),
-    );
-    let result = f(&mut parser)?;
-    if parser.token != token::Eof {
-        parser.unexpected()?;
-    }
-    Ok(result)
-}
-
-// NOTE(Centril): The following probably shouldn't be here but it acknowledges the
-// fact that architecturally, we are using parsing (read on below to understand why).
-
-pub fn nt_to_tokenstream(nt: &Nonterminal, sess: &ParseSess, span: Span) -> TokenStream {
-    // A `Nonterminal` is often a parsed AST item. At this point we now
-    // need to convert the parsed AST to an actual token stream, e.g.
-    // un-parse it basically.
-    //
-    // Unfortunately there's not really a great way to do that in a
-    // guaranteed lossless fashion right now. The fallback here is to just
-    // stringify the AST node and reparse it, but this loses all span
-    // information.
-    //
-    // As a result, some AST nodes are annotated with the token stream they
-    // came from. Here we attempt to extract these lossless token streams
-    // before we fall back to the stringification.
-    let tokens = match *nt {
-        Nonterminal::NtItem(ref item) => {
-            prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span)
-        }
-        Nonterminal::NtTraitItem(ref item) => {
-            prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span)
-        }
-        Nonterminal::NtImplItem(ref item) => {
-            prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span)
-        }
-        Nonterminal::NtIdent(ident, is_raw) => {
-            Some(tokenstream::TokenTree::token(token::Ident(ident.name, is_raw), ident.span).into())
-        }
-        Nonterminal::NtLifetime(ident) => {
-            Some(tokenstream::TokenTree::token(token::Lifetime(ident.name), ident.span).into())
-        }
-        Nonterminal::NtTT(ref tt) => {
-            Some(tt.clone().into())
-        }
-        _ => None,
-    };
-
-    // FIXME(#43081): Avoid this pretty-print + reparse hack
-    let source = pprust::nonterminal_to_string(nt);
-    let filename = FileName::macro_expansion_source_code(&source);
-    let tokens_for_real = parse_stream_from_source_str(filename, source, sess, Some(span));
-
-    // During early phases of the compiler the AST could get modified
-    // directly (e.g., attributes added or removed) and the internal cache
-    // of tokens my not be invalidated or updated. Consequently if the
-    // "lossless" token stream disagrees with our actual stringification
-    // (which has historically been much more battle-tested) then we go
-    // with the lossy stream anyway (losing span information).
-    //
-    // Note that the comparison isn't `==` here to avoid comparing spans,
-    // but it *also* is a "probable" equality which is a pretty weird
-    // definition. We mostly want to catch actual changes to the AST
-    // like a `#[cfg]` being processed or some weird `macro_rules!`
-    // expansion.
-    //
-    // What we *don't* want to catch is the fact that a user-defined
-    // literal like `0xf` is stringified as `15`, causing the cached token
-    // stream to not be literal `==` token-wise (ignoring spans) to the
-    // token stream we got from stringification.
-    //
-    // Instead the "probably equal" check here is "does each token
-    // recursively have the same discriminant?" We basically don't look at
-    // the token values here and assume that such fine grained token stream
-    // modifications, including adding/removing typically non-semantic
-    // tokens such as extra braces and commas, don't happen.
-    if let Some(tokens) = tokens {
-        if tokens.probably_equal_for_proc_macro(&tokens_for_real) {
-            return tokens
-        }
-        info!("cached tokens found, but they're not \"probably equal\", \
-                going with stringified version");
-    }
-    return tokens_for_real
-}
-
-fn prepend_attrs(
-    sess: &ParseSess,
-    attrs: &[ast::Attribute],
-    tokens: Option<&tokenstream::TokenStream>,
-    span: syntax_pos::Span
-) -> Option<tokenstream::TokenStream> {
-    let tokens = tokens?;
-    if attrs.len() == 0 {
-        return Some(tokens.clone())
-    }
-    let mut builder = tokenstream::TokenStreamBuilder::new();
-    for attr in attrs {
-        assert_eq!(attr.style, ast::AttrStyle::Outer,
-                   "inner attributes should prevent cached tokens from existing");
-
-        let source = pprust::attribute_to_string(attr);
-        let macro_filename = FileName::macro_expansion_source_code(&source);
-
-        let item = match attr.kind {
-            ast::AttrKind::Normal(ref item) => item,
-            ast::AttrKind::DocComment(_) => {
-                let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span));
-                builder.push(stream);
-                continue
-            }
-        };
-
-        // synthesize # [ $path $tokens ] manually here
-        let mut brackets = tokenstream::TokenStreamBuilder::new();
-
-        // For simple paths, push the identifier directly
-        if item.path.segments.len() == 1 && item.path.segments[0].args.is_none() {
-            let ident = item.path.segments[0].ident;
-            let token = token::Ident(ident.name, ident.as_str().starts_with("r#"));
-            brackets.push(tokenstream::TokenTree::token(token, ident.span));
-
-        // ... and for more complicated paths, fall back to a reparse hack that
-        // should eventually be removed.
-        } else {
-            let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span));
-            brackets.push(stream);
-        }
-
-        brackets.push(item.tokens.clone());
-
-        // The span we list here for `#` and for `[ ... ]` are both wrong in
-        // that it encompasses more than each token, but it hopefully is "good
-        // enough" for now at least.
-        builder.push(tokenstream::TokenTree::token(token::Pound, attr.span));
-        let delim_span = tokenstream::DelimSpan::from_single(attr.span);
-        builder.push(tokenstream::TokenTree::Delimited(
-            delim_span, token::DelimToken::Bracket, brackets.build().into()));
-    }
-    builder.push(tokens.clone());
-    Some(builder.build())
-}
diff --git a/src/libsyntax/parse/parser/attr.rs b/src/libsyntax/parse/parser/attr.rs
deleted file mode 100644
index 0f9e573af82..00000000000
--- a/src/libsyntax/parse/parser/attr.rs
+++ /dev/null
@@ -1,358 +0,0 @@
-use super::{SeqSep, Parser, TokenType, PathStyle};
-use crate::attr;
-use crate::ast;
-use crate::util::comments;
-use crate::token::{self, Nonterminal, DelimToken};
-use crate::tokenstream::{TokenStream, TokenTree};
-use crate::source_map::Span;
-
-use syntax_pos::Symbol;
-use errors::PResult;
-
-use log::debug;
-
-#[derive(Debug)]
-enum InnerAttributeParsePolicy<'a> {
-    Permitted,
-    NotPermitted { reason: &'a str, saw_doc_comment: bool, prev_attr_sp: Option<Span> },
-}
-
-const DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG: &str = "an inner attribute is not \
-                                                     permitted in this context";
-
-impl<'a> Parser<'a> {
-    /// Parses attributes that appear before an item.
-    pub(super) fn parse_outer_attributes(&mut self) -> PResult<'a, Vec<ast::Attribute>> {
-        let mut attrs: Vec<ast::Attribute> = Vec::new();
-        let mut just_parsed_doc_comment = false;
-        loop {
-            debug!("parse_outer_attributes: self.token={:?}", self.token);
-            match self.token.kind {
-                token::Pound => {
-                    let inner_error_reason = if just_parsed_doc_comment {
-                        "an inner attribute is not permitted following an outer doc comment"
-                    } else if !attrs.is_empty() {
-                        "an inner attribute is not permitted following an outer attribute"
-                    } else {
-                        DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG
-                    };
-                    let inner_parse_policy =
-                        InnerAttributeParsePolicy::NotPermitted {
-                            reason: inner_error_reason,
-                            saw_doc_comment: just_parsed_doc_comment,
-                            prev_attr_sp: attrs.last().and_then(|a| Some(a.span))
-                        };
-                    let attr = self.parse_attribute_with_inner_parse_policy(inner_parse_policy)?;
-                    attrs.push(attr);
-                    just_parsed_doc_comment = false;
-                }
-                token::DocComment(s) => {
-                    let attr = self.mk_doc_comment(s);
-                    if attr.style != ast::AttrStyle::Outer {
-                        let mut err = self.fatal("expected outer doc comment");
-                        err.note("inner doc comments like this (starting with \
-                                  `//!` or `/*!`) can only appear before items");
-                        return Err(err);
-                    }
-                    attrs.push(attr);
-                    self.bump();
-                    just_parsed_doc_comment = true;
-                }
-                _ => break,
-            }
-        }
-        Ok(attrs)
-    }
-
-    fn mk_doc_comment(&self, s: Symbol) -> ast::Attribute {
-        let style = comments::doc_comment_style(&s.as_str());
-        attr::mk_doc_comment(style, s, self.token.span)
-    }
-
-    /// Matches `attribute = # ! [ meta_item ]`.
-    ///
-    /// If `permit_inner` is `true`, then a leading `!` indicates an inner
-    /// attribute.
-    pub fn parse_attribute(&mut self, permit_inner: bool) -> PResult<'a, ast::Attribute> {
-        debug!("parse_attribute: permit_inner={:?} self.token={:?}",
-               permit_inner,
-               self.token);
-        let inner_parse_policy = if permit_inner {
-            InnerAttributeParsePolicy::Permitted
-        } else {
-            InnerAttributeParsePolicy::NotPermitted {
-                reason: DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG,
-                saw_doc_comment: false,
-                prev_attr_sp: None
-            }
-        };
-        self.parse_attribute_with_inner_parse_policy(inner_parse_policy)
-    }
-
-    /// The same as `parse_attribute`, except it takes in an `InnerAttributeParsePolicy`
-    /// that prescribes how to handle inner attributes.
-    fn parse_attribute_with_inner_parse_policy(
-        &mut self,
-        inner_parse_policy: InnerAttributeParsePolicy<'_>
-    ) -> PResult<'a, ast::Attribute> {
-        debug!("parse_attribute_with_inner_parse_policy: inner_parse_policy={:?} self.token={:?}",
-               inner_parse_policy,
-               self.token);
-        let (span, item, style) = match self.token.kind {
-            token::Pound => {
-                let lo = self.token.span;
-                self.bump();
-
-                if let InnerAttributeParsePolicy::Permitted = inner_parse_policy {
-                    self.expected_tokens.push(TokenType::Token(token::Not));
-                }
-
-                let style = if self.token == token::Not {
-                    self.bump();
-                    ast::AttrStyle::Inner
-                } else {
-                    ast::AttrStyle::Outer
-                };
-
-                self.expect(&token::OpenDelim(token::Bracket))?;
-                let item = self.parse_attr_item()?;
-                self.expect(&token::CloseDelim(token::Bracket))?;
-                let hi = self.prev_span;
-
-                let attr_sp = lo.to(hi);
-
-                // Emit error if inner attribute is encountered and not permitted
-                if style == ast::AttrStyle::Inner {
-                    if let InnerAttributeParsePolicy::NotPermitted { reason,
-                        saw_doc_comment, prev_attr_sp } = inner_parse_policy {
-                        let prev_attr_note = if saw_doc_comment {
-                            "previous doc comment"
-                        } else {
-                            "previous outer attribute"
-                        };
-
-                        let mut diagnostic = self
-                            .diagnostic()
-                            .struct_span_err(attr_sp, reason);
-
-                        if let Some(prev_attr_sp) = prev_attr_sp {
-                            diagnostic
-                                .span_label(attr_sp, "not permitted following an outer attibute")
-                                .span_label(prev_attr_sp, prev_attr_note);
-                        }
-
-                        diagnostic
-                            .note("inner attributes, like `#![no_std]`, annotate the item \
-                                   enclosing them, and are usually found at the beginning of \
-                                   source files. Outer attributes, like `#[test]`, annotate the \
-                                   item following them.")
-                            .emit()
-                    }
-                }
-
-                (attr_sp, item, style)
-            }
-            _ => {
-                let token_str = self.this_token_to_string();
-                return Err(self.fatal(&format!("expected `#`, found `{}`", token_str)));
-            }
-        };
-
-        Ok(ast::Attribute {
-            kind: ast::AttrKind::Normal(item),
-            id: attr::mk_attr_id(),
-            style,
-            span,
-        })
-    }
-
-    /// Parses an inner part of an attribute (the path and following tokens).
-    /// The tokens must be either a delimited token stream, or empty token stream,
-    /// or the "legacy" key-value form.
-    ///     PATH `(` TOKEN_STREAM `)`
-    ///     PATH `[` TOKEN_STREAM `]`
-    ///     PATH `{` TOKEN_STREAM `}`
-    ///     PATH
-    ///     PATH `=` UNSUFFIXED_LIT
-    /// The delimiters or `=` are still put into the resulting token stream.
-    pub fn parse_attr_item(&mut self) -> PResult<'a, ast::AttrItem> {
-        let item = match self.token.kind {
-            token::Interpolated(ref nt) => match **nt {
-                Nonterminal::NtMeta(ref item) => Some(item.clone()),
-                _ => None,
-            },
-            _ => None,
-        };
-        Ok(if let Some(item) = item {
-            self.bump();
-            item
-        } else {
-            let path = self.parse_path(PathStyle::Mod)?;
-            let tokens = if self.check(&token::OpenDelim(DelimToken::Paren)) ||
-               self.check(&token::OpenDelim(DelimToken::Bracket)) ||
-               self.check(&token::OpenDelim(DelimToken::Brace)) {
-                   self.parse_token_tree().into()
-            } else if self.eat(&token::Eq) {
-                let eq = TokenTree::token(token::Eq, self.prev_span);
-                let mut is_interpolated_expr = false;
-                if let token::Interpolated(nt) = &self.token.kind {
-                    if let token::NtExpr(..) = **nt {
-                        is_interpolated_expr = true;
-                    }
-                }
-                let token_tree = if is_interpolated_expr {
-                    // We need to accept arbitrary interpolated expressions to continue
-                    // supporting things like `doc = $expr` that work on stable.
-                    // Non-literal interpolated expressions are rejected after expansion.
-                    self.parse_token_tree()
-                } else {
-                    self.parse_unsuffixed_lit()?.token_tree()
-                };
-                TokenStream::new(vec![eq.into(), token_tree.into()])
-            } else {
-                TokenStream::default()
-            };
-            ast::AttrItem { path, tokens }
-        })
-    }
-
-    /// Parses attributes that appear after the opening of an item. These should
-    /// be preceded by an exclamation mark, but we accept and warn about one
-    /// terminated by a semicolon.
-    ///
-    /// Matches `inner_attrs*`.
-    crate fn parse_inner_attributes(&mut self) -> PResult<'a, Vec<ast::Attribute>> {
-        let mut attrs: Vec<ast::Attribute> = vec![];
-        loop {
-            match self.token.kind {
-                token::Pound => {
-                    // Don't even try to parse if it's not an inner attribute.
-                    if !self.look_ahead(1, |t| t == &token::Not) {
-                        break;
-                    }
-
-                    let attr = self.parse_attribute(true)?;
-                    assert_eq!(attr.style, ast::AttrStyle::Inner);
-                    attrs.push(attr);
-                }
-                token::DocComment(s) => {
-                    // We need to get the position of this token before we bump.
-                    let attr = self.mk_doc_comment(s);
-                    if attr.style == ast::AttrStyle::Inner {
-                        attrs.push(attr);
-                        self.bump();
-                    } else {
-                        break;
-                    }
-                }
-                _ => break,
-            }
-        }
-        Ok(attrs)
-    }
-
-    fn parse_unsuffixed_lit(&mut self) -> PResult<'a, ast::Lit> {
-        let lit = self.parse_lit()?;
-        debug!("checking if {:?} is unusuffixed", lit);
-
-        if !lit.kind.is_unsuffixed() {
-            let msg = "suffixed literals are not allowed in attributes";
-            self.diagnostic().struct_span_err(lit.span, msg)
-                             .help("instead of using a suffixed literal \
-                                    (1u8, 1.0f32, etc.), use an unsuffixed version \
-                                    (1, 1.0, etc.).")
-                             .emit()
-        }
-
-        Ok(lit)
-    }
-
-    /// Parses `cfg_attr(pred, attr_item_list)` where `attr_item_list` is comma-delimited.
-    pub fn parse_cfg_attr(&mut self) -> PResult<'a, (ast::MetaItem, Vec<(ast::AttrItem, Span)>)> {
-        self.expect(&token::OpenDelim(token::Paren))?;
-
-        let cfg_predicate = self.parse_meta_item()?;
-        self.expect(&token::Comma)?;
-
-        // Presumably, the majority of the time there will only be one attr.
-        let mut expanded_attrs = Vec::with_capacity(1);
-
-        while !self.check(&token::CloseDelim(token::Paren)) {
-            let lo = self.token.span.lo();
-            let item = self.parse_attr_item()?;
-            expanded_attrs.push((item, self.prev_span.with_lo(lo)));
-            self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Paren)])?;
-        }
-
-        self.expect(&token::CloseDelim(token::Paren))?;
-        Ok((cfg_predicate, expanded_attrs))
-    }
-
-    /// Matches the following grammar (per RFC 1559).
-    ///
-    ///     meta_item : PATH ( '=' UNSUFFIXED_LIT | '(' meta_item_inner? ')' )? ;
-    ///     meta_item_inner : (meta_item | UNSUFFIXED_LIT) (',' meta_item_inner)? ;
-    pub fn parse_meta_item(&mut self) -> PResult<'a, ast::MetaItem> {
-        let nt_meta = match self.token.kind {
-            token::Interpolated(ref nt) => match **nt {
-                token::NtMeta(ref e) => Some(e.clone()),
-                _ => None,
-            },
-            _ => None,
-        };
-
-        if let Some(item) = nt_meta {
-            return match item.meta(item.path.span) {
-                Some(meta) => {
-                    self.bump();
-                    Ok(meta)
-                }
-                None => self.unexpected(),
-            }
-        }
-
-        let lo = self.token.span;
-        let path = self.parse_path(PathStyle::Mod)?;
-        let kind = self.parse_meta_item_kind()?;
-        let span = lo.to(self.prev_span);
-        Ok(ast::MetaItem { path, kind, span })
-    }
-
-    crate fn parse_meta_item_kind(&mut self) -> PResult<'a, ast::MetaItemKind> {
-        Ok(if self.eat(&token::Eq) {
-            ast::MetaItemKind::NameValue(self.parse_unsuffixed_lit()?)
-        } else if self.eat(&token::OpenDelim(token::Paren)) {
-            ast::MetaItemKind::List(self.parse_meta_seq()?)
-        } else {
-            ast::MetaItemKind::Word
-        })
-    }
-
-    /// Matches `meta_item_inner : (meta_item | UNSUFFIXED_LIT) ;`.
-    fn parse_meta_item_inner(&mut self) -> PResult<'a, ast::NestedMetaItem> {
-        match self.parse_unsuffixed_lit() {
-            Ok(lit) => {
-                return Ok(ast::NestedMetaItem::Literal(lit))
-            }
-            Err(ref mut err) => err.cancel(),
-        }
-
-        match self.parse_meta_item() {
-            Ok(mi) => {
-                return Ok(ast::NestedMetaItem::MetaItem(mi))
-            }
-            Err(ref mut err) => err.cancel(),
-        }
-
-        let found = self.this_token_to_string();
-        let msg = format!("expected unsuffixed literal or identifier, found `{}`", found);
-        Err(self.diagnostic().struct_span_err(self.token.span, &msg))
-    }
-
-    /// Matches `meta_seq = ( COMMASEP(meta_item_inner) )`.
-    fn parse_meta_seq(&mut self) -> PResult<'a, Vec<ast::NestedMetaItem>> {
-        self.parse_seq_to_end(&token::CloseDelim(token::Paren),
-                              SeqSep::trailing_allowed(token::Comma),
-                              |p: &mut Parser<'a>| p.parse_meta_item_inner())
-    }
-}
diff --git a/src/libsyntax/parse/parser/diagnostics.rs b/src/libsyntax/parse/parser/diagnostics.rs
deleted file mode 100644
index 5df24804a76..00000000000
--- a/src/libsyntax/parse/parser/diagnostics.rs
+++ /dev/null
@@ -1,1547 +0,0 @@
-use super::{BlockMode, PathStyle, SemiColonMode, TokenType, TokenExpectType, SeqSep, Parser};
-use crate::ast::{
-    self, Param, BinOpKind, BindingMode, BlockCheckMode, Expr, ExprKind, Ident, Item, ItemKind,
-    Mutability, Pat, PatKind, PathSegment, QSelf, Ty, TyKind,
-};
-use crate::token::{self, TokenKind, token_can_begin_expr};
-use crate::print::pprust;
-use crate::ptr::P;
-use crate::symbol::{kw, sym};
-use crate::ThinVec;
-use crate::util::parser::AssocOp;
-
-use errors::{PResult, Applicability, DiagnosticBuilder, DiagnosticId, pluralize};
-use rustc_data_structures::fx::FxHashSet;
-use syntax_pos::{Span, DUMMY_SP, MultiSpan, SpanSnippetError};
-use log::{debug, trace};
-use std::mem;
-
-const TURBOFISH: &'static str = "use `::<...>` instead of `<...>` to specify type arguments";
-
-/// Creates a placeholder argument.
-pub(super) fn dummy_arg(ident: Ident) -> Param {
-    let pat = P(Pat {
-        id: ast::DUMMY_NODE_ID,
-        kind: PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), ident, None),
-        span: ident.span,
-    });
-    let ty = Ty {
-        kind: TyKind::Err,
-        span: ident.span,
-        id: ast::DUMMY_NODE_ID
-    };
-    Param {
-        attrs: ThinVec::default(),
-        id: ast::DUMMY_NODE_ID,
-        pat,
-        span: ident.span,
-        ty: P(ty),
-        is_placeholder: false,
-    }
-}
-
-pub enum Error {
-    FileNotFoundForModule {
-        mod_name: String,
-        default_path: String,
-        secondary_path: String,
-        dir_path: String,
-    },
-    DuplicatePaths {
-        mod_name: String,
-        default_path: String,
-        secondary_path: String,
-    },
-    UselessDocComment,
-    InclusiveRangeWithNoEnd,
-}
-
-impl Error {
-    fn span_err<S: Into<MultiSpan>>(
-        self,
-        sp: S,
-        handler: &errors::Handler,
-    ) -> DiagnosticBuilder<'_> {
-        match self {
-            Error::FileNotFoundForModule {
-                ref mod_name,
-                ref default_path,
-                ref secondary_path,
-                ref dir_path,
-            } => {
-                let mut err = struct_span_err!(
-                    handler,
-                    sp,
-                    E0583,
-                    "file not found for module `{}`",
-                    mod_name,
-                );
-                err.help(&format!(
-                    "name the file either {} or {} inside the directory \"{}\"",
-                    default_path,
-                    secondary_path,
-                    dir_path,
-                ));
-                err
-            }
-            Error::DuplicatePaths { ref mod_name, ref default_path, ref secondary_path } => {
-                let mut err = struct_span_err!(
-                    handler,
-                    sp,
-                    E0584,
-                    "file for module `{}` found at both {} and {}",
-                    mod_name,
-                    default_path,
-                    secondary_path,
-                );
-                err.help("delete or rename one of them to remove the ambiguity");
-                err
-            }
-            Error::UselessDocComment => {
-                let mut err = struct_span_err!(
-                    handler,
-                    sp,
-                    E0585,
-                    "found a documentation comment that doesn't document anything",
-                );
-                err.help("doc comments must come before what they document, maybe a comment was \
-                          intended with `//`?");
-                err
-            }
-            Error::InclusiveRangeWithNoEnd => {
-                let mut err = struct_span_err!(
-                    handler,
-                    sp,
-                    E0586,
-                    "inclusive range with no end",
-                );
-                err.help("inclusive ranges must be bounded at the end (`..=b` or `a..=b`)");
-                err
-            }
-        }
-    }
-}
-
-pub(super) trait RecoverQPath: Sized + 'static {
-    const PATH_STYLE: PathStyle = PathStyle::Expr;
-    fn to_ty(&self) -> Option<P<Ty>>;
-    fn recovered(qself: Option<QSelf>, path: ast::Path) -> Self;
-}
-
-impl RecoverQPath for Ty {
-    const PATH_STYLE: PathStyle = PathStyle::Type;
-    fn to_ty(&self) -> Option<P<Ty>> {
-        Some(P(self.clone()))
-    }
-    fn recovered(qself: Option<QSelf>, path: ast::Path) -> Self {
-        Self {
-            span: path.span,
-            kind: TyKind::Path(qself, path),
-            id: ast::DUMMY_NODE_ID,
-        }
-    }
-}
-
-impl RecoverQPath for Pat {
-    fn to_ty(&self) -> Option<P<Ty>> {
-        self.to_ty()
-    }
-    fn recovered(qself: Option<QSelf>, path: ast::Path) -> Self {
-        Self {
-            span: path.span,
-            kind: PatKind::Path(qself, path),
-            id: ast::DUMMY_NODE_ID,
-        }
-    }
-}
-
-impl RecoverQPath for Expr {
-    fn to_ty(&self) -> Option<P<Ty>> {
-        self.to_ty()
-    }
-    fn recovered(qself: Option<QSelf>, path: ast::Path) -> Self {
-        Self {
-            span: path.span,
-            kind: ExprKind::Path(qself, path),
-            attrs: ThinVec::new(),
-            id: ast::DUMMY_NODE_ID,
-        }
-    }
-}
-
-/// Control whether the closing delimiter should be consumed when calling `Parser::consume_block`.
-crate enum ConsumeClosingDelim {
-    Yes,
-    No,
-}
-
-impl<'a> Parser<'a> {
-    pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> {
-        self.span_fatal(self.token.span, m)
-    }
-
-    crate fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
-        self.sess.span_diagnostic.struct_span_fatal(sp, m)
-    }
-
-    pub(super) fn span_fatal_err<S: Into<MultiSpan>>(
-        &self,
-        sp: S,
-        err: Error,
-    ) -> DiagnosticBuilder<'a> {
-        err.span_err(sp, self.diagnostic())
-    }
-
-    pub(super) fn bug(&self, m: &str) -> ! {
-        self.sess.span_diagnostic.span_bug(self.token.span, m)
-    }
-
-    pub(super) fn span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) {
-        self.sess.span_diagnostic.span_err(sp, m)
-    }
-
-    pub fn struct_span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
-        self.sess.span_diagnostic.struct_span_err(sp, m)
-    }
-
-    pub fn span_bug<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> ! {
-        self.sess.span_diagnostic.span_bug(sp, m)
-    }
-
-    pub(super) fn diagnostic(&self) -> &'a errors::Handler {
-        &self.sess.span_diagnostic
-    }
-
-    pub(super) fn span_to_snippet(&self, span: Span) -> Result<String, SpanSnippetError> {
-        self.sess.source_map().span_to_snippet(span)
-    }
-
-    pub(super) fn expected_ident_found(&self) -> DiagnosticBuilder<'a> {
-        let mut err = self.struct_span_err(
-            self.token.span,
-            &format!("expected identifier, found {}", self.this_token_descr()),
-        );
-        if let token::Ident(name, false) = self.token.kind {
-            if Ident::new(name, self.token.span).is_raw_guess() {
-                err.span_suggestion(
-                    self.token.span,
-                    "you can escape reserved keywords to use them as identifiers",
-                    format!("r#{}", name),
-                    Applicability::MaybeIncorrect,
-                );
-            }
-        }
-        if let Some(token_descr) = self.token_descr() {
-            err.span_label(self.token.span, format!("expected identifier, found {}", token_descr));
-        } else {
-            err.span_label(self.token.span, "expected identifier");
-            if self.token == token::Comma && self.look_ahead(1, |t| t.is_ident()) {
-                err.span_suggestion(
-                    self.token.span,
-                    "remove this comma",
-                    String::new(),
-                    Applicability::MachineApplicable,
-                );
-            }
-        }
-        err
-    }
-
-    pub(super) fn expected_one_of_not_found(
-        &mut self,
-        edible: &[TokenKind],
-        inedible: &[TokenKind],
-    ) -> PResult<'a, bool /* recovered */> {
-        fn tokens_to_string(tokens: &[TokenType]) -> String {
-            let mut i = tokens.iter();
-            // This might be a sign we need a connect method on `Iterator`.
-            let b = i.next()
-                     .map_or(String::new(), |t| t.to_string());
-            i.enumerate().fold(b, |mut b, (i, a)| {
-                if tokens.len() > 2 && i == tokens.len() - 2 {
-                    b.push_str(", or ");
-                } else if tokens.len() == 2 && i == tokens.len() - 2 {
-                    b.push_str(" or ");
-                } else {
-                    b.push_str(", ");
-                }
-                b.push_str(&a.to_string());
-                b
-            })
-        }
-
-        let mut expected = edible.iter()
-            .map(|x| TokenType::Token(x.clone()))
-            .chain(inedible.iter().map(|x| TokenType::Token(x.clone())))
-            .chain(self.expected_tokens.iter().cloned())
-            .collect::<Vec<_>>();
-        expected.sort_by_cached_key(|x| x.to_string());
-        expected.dedup();
-        let expect = tokens_to_string(&expected[..]);
-        let actual = self.this_token_descr();
-        let (msg_exp, (label_sp, label_exp)) = if expected.len() > 1 {
-            let short_expect = if expected.len() > 6 {
-                format!("{} possible tokens", expected.len())
-            } else {
-                expect.clone()
-            };
-            (format!("expected one of {}, found {}", expect, actual),
-                (self.sess.source_map().next_point(self.prev_span),
-                format!("expected one of {}", short_expect)))
-        } else if expected.is_empty() {
-            (format!("unexpected token: {}", actual),
-                (self.prev_span, "unexpected token after this".to_string()))
-        } else {
-            (format!("expected {}, found {}", expect, actual),
-                (self.sess.source_map().next_point(self.prev_span),
-                format!("expected {}", expect)))
-        };
-        self.last_unexpected_token_span = Some(self.token.span);
-        let mut err = self.fatal(&msg_exp);
-        if self.token.is_ident_named(sym::and) {
-            err.span_suggestion_short(
-                self.token.span,
-                "use `&&` instead of `and` for the boolean operator",
-                "&&".to_string(),
-                Applicability::MaybeIncorrect,
-            );
-        }
-        if self.token.is_ident_named(sym::or) {
-            err.span_suggestion_short(
-                self.token.span,
-                "use `||` instead of `or` for the boolean operator",
-                "||".to_string(),
-                Applicability::MaybeIncorrect,
-            );
-        }
-        let sp = if self.token == token::Eof {
-            // This is EOF; don't want to point at the following char, but rather the last token.
-            self.prev_span
-        } else {
-            label_sp
-        };
-        match self.recover_closing_delimiter(&expected.iter().filter_map(|tt| match tt {
-            TokenType::Token(t) => Some(t.clone()),
-            _ => None,
-        }).collect::<Vec<_>>(), err) {
-            Err(e) => err = e,
-            Ok(recovered) => {
-                return Ok(recovered);
-            }
-        }
-
-        let sm = self.sess.source_map();
-        if self.prev_span == DUMMY_SP {
-            // Account for macro context where the previous span might not be
-            // available to avoid incorrect output (#54841).
-            err.span_label(self.token.span, label_exp);
-        } else if !sm.is_multiline(self.token.span.shrink_to_hi().until(sp.shrink_to_lo())) {
-            // When the spans are in the same line, it means that the only content between
-            // them is whitespace, point at the found token in that case:
-            //
-            // X |     () => { syntax error };
-            //   |                    ^^^^^ expected one of 8 possible tokens here
-            //
-            // instead of having:
-            //
-            // X |     () => { syntax error };
-            //   |                   -^^^^^ unexpected token
-            //   |                   |
-            //   |                   expected one of 8 possible tokens here
-            err.span_label(self.token.span, label_exp);
-        } else {
-            err.span_label(sp, label_exp);
-            err.span_label(self.token.span, "unexpected token");
-        }
-        self.maybe_annotate_with_ascription(&mut err, false);
-        Err(err)
-    }
-
-    pub fn maybe_annotate_with_ascription(
-        &mut self,
-        err: &mut DiagnosticBuilder<'_>,
-        maybe_expected_semicolon: bool,
-    ) {
-        if let Some((sp, likely_path)) = self.last_type_ascription.take() {
-            let sm = self.sess.source_map();
-            let next_pos = sm.lookup_char_pos(self.token.span.lo());
-            let op_pos = sm.lookup_char_pos(sp.hi());
-
-            let allow_unstable = self.sess.unstable_features.is_nightly_build();
-
-            if likely_path {
-                err.span_suggestion(
-                    sp,
-                    "maybe write a path separator here",
-                    "::".to_string(),
-                    if allow_unstable {
-                        Applicability::MaybeIncorrect
-                    } else {
-                        Applicability::MachineApplicable
-                    },
-                );
-            } else if op_pos.line != next_pos.line && maybe_expected_semicolon {
-                err.span_suggestion(
-                    sp,
-                    "try using a semicolon",
-                    ";".to_string(),
-                    Applicability::MaybeIncorrect,
-                );
-            } else if allow_unstable {
-                err.span_label(sp, "tried to parse a type due to this type ascription");
-            } else {
-                err.span_label(sp, "tried to parse a type due to this");
-            }
-            if allow_unstable {
-                // Give extra information about type ascription only if it's a nightly compiler.
-                err.note("`#![feature(type_ascription)]` lets you annotate an expression with a \
-                          type: `<expr>: <type>`");
-                err.note("for more information, see \
-                          https://github.com/rust-lang/rust/issues/23416");
-            }
-        }
-    }
-
-    /// Eats and discards tokens until one of `kets` is encountered. Respects token trees,
-    /// passes through any errors encountered. Used for error recovery.
-    pub(super) fn eat_to_tokens(&mut self, kets: &[&TokenKind]) {
-        if let Err(ref mut err) = self.parse_seq_to_before_tokens(
-            kets,
-            SeqSep::none(),
-            TokenExpectType::Expect,
-            |p| Ok(p.parse_token_tree()),
-        ) {
-            err.cancel();
-        }
-    }
-
-    /// This function checks if there are trailing angle brackets and produces
-    /// a diagnostic to suggest removing them.
-    ///
-    /// ```ignore (diagnostic)
-    /// let _ = vec![1, 2, 3].into_iter().collect::<Vec<usize>>>>();
-    ///                                                        ^^ help: remove extra angle brackets
-    /// ```
-    pub(super) fn check_trailing_angle_brackets(&mut self, segment: &PathSegment, end: TokenKind) {
-        // This function is intended to be invoked after parsing a path segment where there are two
-        // cases:
-        //
-        // 1. A specific token is expected after the path segment.
-        //    eg. `x.foo(`, `x.foo::<u32>(` (parenthesis - method call),
-        //        `Foo::`, or `Foo::<Bar>::` (mod sep - continued path).
-        // 2. No specific token is expected after the path segment.
-        //    eg. `x.foo` (field access)
-        //
-        // This function is called after parsing `.foo` and before parsing the token `end` (if
-        // present). This includes any angle bracket arguments, such as `.foo::<u32>` or
-        // `Foo::<Bar>`.
-
-        // We only care about trailing angle brackets if we previously parsed angle bracket
-        // arguments. This helps stop us incorrectly suggesting that extra angle brackets be
-        // removed in this case:
-        //
-        // `x.foo >> (3)` (where `x.foo` is a `u32` for example)
-        //
-        // This case is particularly tricky as we won't notice it just looking at the tokens -
-        // it will appear the same (in terms of upcoming tokens) as below (since the `::<u32>` will
-        // have already been parsed):
-        //
-        // `x.foo::<u32>>>(3)`
-        let parsed_angle_bracket_args = segment.args
-            .as_ref()
-            .map(|args| args.is_angle_bracketed())
-            .unwrap_or(false);
-
-        debug!(
-            "check_trailing_angle_brackets: parsed_angle_bracket_args={:?}",
-            parsed_angle_bracket_args,
-        );
-        if !parsed_angle_bracket_args {
-            return;
-        }
-
-        // Keep the span at the start so we can highlight the sequence of `>` characters to be
-        // removed.
-        let lo = self.token.span;
-
-        // We need to look-ahead to see if we have `>` characters without moving the cursor forward
-        // (since we might have the field access case and the characters we're eating are
-        // actual operators and not trailing characters - ie `x.foo >> 3`).
-        let mut position = 0;
-
-        // We can encounter `>` or `>>` tokens in any order, so we need to keep track of how
-        // many of each (so we can correctly pluralize our error messages) and continue to
-        // advance.
-        let mut number_of_shr = 0;
-        let mut number_of_gt = 0;
-        while self.look_ahead(position, |t| {
-            trace!("check_trailing_angle_brackets: t={:?}", t);
-            if *t == token::BinOp(token::BinOpToken::Shr) {
-                number_of_shr += 1;
-                true
-            } else if *t == token::Gt {
-                number_of_gt += 1;
-                true
-            } else {
-                false
-            }
-        }) {
-            position += 1;
-        }
-
-        // If we didn't find any trailing `>` characters, then we have nothing to error about.
-        debug!(
-            "check_trailing_angle_brackets: number_of_gt={:?} number_of_shr={:?}",
-            number_of_gt, number_of_shr,
-        );
-        if number_of_gt < 1 && number_of_shr < 1 {
-            return;
-        }
-
-        // Finally, double check that we have our end token as otherwise this is the
-        // second case.
-        if self.look_ahead(position, |t| {
-            trace!("check_trailing_angle_brackets: t={:?}", t);
-            *t == end
-        }) {
-            // Eat from where we started until the end token so that parsing can continue
-            // as if we didn't have those extra angle brackets.
-            self.eat_to_tokens(&[&end]);
-            let span = lo.until(self.token.span);
-
-            let total_num_of_gt = number_of_gt + number_of_shr * 2;
-            self.diagnostic()
-                .struct_span_err(
-                    span,
-                    &format!("unmatched angle bracket{}", pluralize!(total_num_of_gt)),
-                )
-                .span_suggestion(
-                    span,
-                    &format!("remove extra angle bracket{}", pluralize!(total_num_of_gt)),
-                    String::new(),
-                    Applicability::MachineApplicable,
-                )
-                .emit();
-        }
-    }
-
-    /// Produces an error if comparison operators are chained (RFC #558).
-    /// We only need to check the LHS, not the RHS, because all comparison ops have same
-    /// precedence (see `fn precedence`) and are left-associative (see `fn fixity`).
-    ///
-    /// This can also be hit if someone incorrectly writes `foo<bar>()` when they should have used
-    /// the turbofish (`foo::<bar>()`) syntax. We attempt some heuristic recovery if that is the
-    /// case.
-    ///
-    /// Keep in mind that given that `outer_op.is_comparison()` holds and comparison ops are left
-    /// associative we can infer that we have:
-    ///
-    ///           outer_op
-    ///           /   \
-    ///     inner_op   r2
-    ///        /  \
-    ///     l1    r1
-    pub(super) fn check_no_chained_comparison(
-        &mut self,
-        lhs: &Expr,
-        outer_op: &AssocOp,
-    ) -> PResult<'a, Option<P<Expr>>> {
-        debug_assert!(
-            outer_op.is_comparison(),
-            "check_no_chained_comparison: {:?} is not comparison",
-            outer_op,
-        );
-
-        let mk_err_expr = |this: &Self, span| {
-            Ok(Some(this.mk_expr(span, ExprKind::Err, ThinVec::new())))
-        };
-
-        match lhs.kind {
-            ExprKind::Binary(op, _, _) if op.node.is_comparison() => {
-                // Respan to include both operators.
-                let op_span = op.span.to(self.prev_span);
-                let mut err = self.struct_span_err(
-                    op_span,
-                    "chained comparison operators require parentheses",
-                );
-
-                let suggest = |err: &mut DiagnosticBuilder<'_>| {
-                    err.span_suggestion_verbose(
-                        op_span.shrink_to_lo(),
-                        TURBOFISH,
-                        "::".to_string(),
-                        Applicability::MaybeIncorrect,
-                    );
-                };
-
-                if op.node == BinOpKind::Lt &&
-                    *outer_op == AssocOp::Less ||  // Include `<` to provide this recommendation
-                    *outer_op == AssocOp::Greater  // even in a case like the following:
-                {                                  //     Foo<Bar<Baz<Qux, ()>>>
-                    if *outer_op == AssocOp::Less {
-                        let snapshot = self.clone();
-                        self.bump();
-                        // So far we have parsed `foo<bar<`, consume the rest of the type args.
-                        let modifiers = [
-                            (token::Lt, 1),
-                            (token::Gt, -1),
-                            (token::BinOp(token::Shr), -2),
-                        ];
-                        self.consume_tts(1, &modifiers[..]);
-
-                        if !&[
-                            token::OpenDelim(token::Paren),
-                            token::ModSep,
-                        ].contains(&self.token.kind) {
-                            // We don't have `foo< bar >(` or `foo< bar >::`, so we rewind the
-                            // parser and bail out.
-                            mem::replace(self, snapshot.clone());
-                        }
-                    }
-                    return if token::ModSep == self.token.kind {
-                        // We have some certainty that this was a bad turbofish at this point.
-                        // `foo< bar >::`
-                        suggest(&mut err);
-
-                        let snapshot = self.clone();
-                        self.bump(); // `::`
-
-                        // Consume the rest of the likely `foo<bar>::new()` or return at `foo<bar>`.
-                        match self.parse_expr() {
-                            Ok(_) => {
-                                // 99% certain that the suggestion is correct, continue parsing.
-                                err.emit();
-                                // FIXME: actually check that the two expressions in the binop are
-                                // paths and resynthesize new fn call expression instead of using
-                                // `ExprKind::Err` placeholder.
-                                mk_err_expr(self, lhs.span.to(self.prev_span))
-                            }
-                            Err(mut expr_err) => {
-                                expr_err.cancel();
-                                // Not entirely sure now, but we bubble the error up with the
-                                // suggestion.
-                                mem::replace(self, snapshot);
-                                Err(err)
-                            }
-                        }
-                    } else if token::OpenDelim(token::Paren) == self.token.kind {
-                        // We have high certainty that this was a bad turbofish at this point.
-                        // `foo< bar >(`
-                        suggest(&mut err);
-                        // Consume the fn call arguments.
-                        match self.consume_fn_args() {
-                            Err(()) => Err(err),
-                            Ok(()) => {
-                                err.emit();
-                                // FIXME: actually check that the two expressions in the binop are
-                                // paths and resynthesize new fn call expression instead of using
-                                // `ExprKind::Err` placeholder.
-                                mk_err_expr(self, lhs.span.to(self.prev_span))
-                            }
-                        }
-                    } else {
-                        // All we know is that this is `foo < bar >` and *nothing* else. Try to
-                        // be helpful, but don't attempt to recover.
-                        err.help(TURBOFISH);
-                        err.help("or use `(...)` if you meant to specify fn arguments");
-                        // These cases cause too many knock-down errors, bail out (#61329).
-                        Err(err)
-                    };
-                }
-                err.emit();
-            }
-            _ => {}
-        }
-        Ok(None)
-    }
-
-    fn consume_fn_args(&mut self) -> Result<(), ()> {
-        let snapshot = self.clone();
-        self.bump(); // `(`
-
-        // Consume the fn call arguments.
-        let modifiers = [
-            (token::OpenDelim(token::Paren), 1),
-            (token::CloseDelim(token::Paren), -1),
-        ];
-        self.consume_tts(1, &modifiers[..]);
-
-        if self.token.kind == token::Eof {
-            // Not entirely sure that what we consumed were fn arguments, rollback.
-            mem::replace(self, snapshot);
-            Err(())
-        } else {
-            // 99% certain that the suggestion is correct, continue parsing.
-            Ok(())
-        }
-    }
-
-    pub(super) fn maybe_report_ambiguous_plus(
-        &mut self,
-        allow_plus: bool,
-        impl_dyn_multi: bool,
-        ty: &Ty,
-    ) {
-        if !allow_plus && impl_dyn_multi {
-            let sum_with_parens = format!("({})", pprust::ty_to_string(&ty));
-            self.struct_span_err(ty.span, "ambiguous `+` in a type")
-                .span_suggestion(
-                    ty.span,
-                    "use parentheses to disambiguate",
-                    sum_with_parens,
-                    Applicability::MachineApplicable,
-                )
-                .emit();
-        }
-    }
-
-    pub(super) fn maybe_recover_from_bad_type_plus(
-        &mut self,
-        allow_plus: bool,
-        ty: &Ty,
-    ) -> PResult<'a, ()> {
-        // Do not add `+` to expected tokens.
-        if !allow_plus || !self.token.is_like_plus() {
-            return Ok(());
-        }
-
-        self.bump(); // `+`
-        let bounds = self.parse_generic_bounds(None)?;
-        let sum_span = ty.span.to(self.prev_span);
-
-        let mut err = struct_span_err!(
-            self.sess.span_diagnostic,
-            sum_span,
-            E0178,
-            "expected a path on the left-hand side of `+`, not `{}`",
-            pprust::ty_to_string(ty)
-        );
-
-        match ty.kind {
-            TyKind::Rptr(ref lifetime, ref mut_ty) => {
-                let sum_with_parens = pprust::to_string(|s| {
-                    s.s.word("&");
-                    s.print_opt_lifetime(lifetime);
-                    s.print_mutability(mut_ty.mutbl);
-                    s.popen();
-                    s.print_type(&mut_ty.ty);
-                    s.print_type_bounds(" +", &bounds);
-                    s.pclose()
-                });
-                err.span_suggestion(
-                    sum_span,
-                    "try adding parentheses",
-                    sum_with_parens,
-                    Applicability::MachineApplicable,
-                );
-            }
-            TyKind::Ptr(..) | TyKind::BareFn(..) => {
-                err.span_label(sum_span, "perhaps you forgot parentheses?");
-            }
-            _ => {
-                err.span_label(sum_span, "expected a path");
-            }
-        }
-        err.emit();
-        Ok(())
-    }
-
-    /// Tries to recover from associated item paths like `[T]::AssocItem` / `(T, U)::AssocItem`.
-    /// Attempts to convert the base expression/pattern/type into a type, parses the `::AssocItem`
-    /// tail, and combines them into a `<Ty>::AssocItem` expression/pattern/type.
-    pub(super) fn maybe_recover_from_bad_qpath<T: RecoverQPath>(
-        &mut self,
-        base: P<T>,
-        allow_recovery: bool,
-    ) -> PResult<'a, P<T>> {
-        // Do not add `::` to expected tokens.
-        if allow_recovery && self.token == token::ModSep {
-            if let Some(ty) = base.to_ty() {
-                return self.maybe_recover_from_bad_qpath_stage_2(ty.span, ty);
-            }
-        }
-        Ok(base)
-    }
-
-    /// Given an already parsed `Ty`, parses the `::AssocItem` tail and
-    /// combines them into a `<Ty>::AssocItem` expression/pattern/type.
-    pub(super) fn maybe_recover_from_bad_qpath_stage_2<T: RecoverQPath>(
-        &mut self,
-        ty_span: Span,
-        ty: P<Ty>,
-    ) -> PResult<'a, P<T>> {
-        self.expect(&token::ModSep)?;
-
-        let mut path = ast::Path {
-            segments: Vec::new(),
-            span: DUMMY_SP,
-        };
-        self.parse_path_segments(&mut path.segments, T::PATH_STYLE)?;
-        path.span = ty_span.to(self.prev_span);
-
-        let ty_str = self
-            .span_to_snippet(ty_span)
-            .unwrap_or_else(|_| pprust::ty_to_string(&ty));
-        self.diagnostic()
-            .struct_span_err(path.span, "missing angle brackets in associated item path")
-            .span_suggestion(
-                // This is a best-effort recovery.
-                path.span,
-                "try",
-                format!("<{}>::{}", ty_str, pprust::path_to_string(&path)),
-                Applicability::MaybeIncorrect,
-            )
-            .emit();
-
-        let path_span = ty_span.shrink_to_hi(); // Use an empty path since `position == 0`.
-        Ok(P(T::recovered(
-            Some(QSelf {
-                ty,
-                path_span,
-                position: 0,
-            }),
-            path,
-        )))
-    }
-
-    pub(super) fn maybe_consume_incorrect_semicolon(&mut self, items: &[P<Item>]) -> bool {
-        if self.eat(&token::Semi) {
-            let mut err = self.struct_span_err(self.prev_span, "expected item, found `;`");
-            err.span_suggestion_short(
-                self.prev_span,
-                "remove this semicolon",
-                String::new(),
-                Applicability::MachineApplicable,
-            );
-            if !items.is_empty() {
-                let previous_item = &items[items.len() - 1];
-                let previous_item_kind_name = match previous_item.kind {
-                    // Say "braced struct" because tuple-structs and
-                    // braceless-empty-struct declarations do take a semicolon.
-                    ItemKind::Struct(..) => Some("braced struct"),
-                    ItemKind::Enum(..) => Some("enum"),
-                    ItemKind::Trait(..) => Some("trait"),
-                    ItemKind::Union(..) => Some("union"),
-                    _ => None,
-                };
-                if let Some(name) = previous_item_kind_name {
-                    err.help(&format!(
-                        "{} declarations are not followed by a semicolon",
-                        name
-                    ));
-                }
-            }
-            err.emit();
-            true
-        } else {
-            false
-        }
-    }
-
-    /// Creates a `DiagnosticBuilder` for an unexpected token `t` and tries to recover if it is a
-    /// closing delimiter.
-    pub(super) fn unexpected_try_recover(
-        &mut self,
-        t: &TokenKind,
-    ) -> PResult<'a, bool /* recovered */> {
-        let token_str = pprust::token_kind_to_string(t);
-        let this_token_str = self.this_token_descr();
-        let (prev_sp, sp) = match (&self.token.kind, self.subparser_name) {
-            // Point at the end of the macro call when reaching end of macro arguments.
-            (token::Eof, Some(_)) => {
-                let sp = self.sess.source_map().next_point(self.token.span);
-                (sp, sp)
-            }
-            // We don't want to point at the following span after DUMMY_SP.
-            // This happens when the parser finds an empty TokenStream.
-            _ if self.prev_span == DUMMY_SP => (self.token.span, self.token.span),
-            // EOF, don't want to point at the following char, but rather the last token.
-            (token::Eof, None) => (self.prev_span, self.token.span),
-            _ => (self.sess.source_map().next_point(self.prev_span), self.token.span),
-        };
-        let msg = format!(
-            "expected `{}`, found {}",
-            token_str,
-            match (&self.token.kind, self.subparser_name) {
-                (token::Eof, Some(origin)) => format!("end of {}", origin),
-                _ => this_token_str,
-            },
-        );
-        let mut err = self.struct_span_err(sp, &msg);
-        let label_exp = format!("expected `{}`", token_str);
-        match self.recover_closing_delimiter(&[t.clone()], err) {
-            Err(e) => err = e,
-            Ok(recovered) => {
-                return Ok(recovered);
-            }
-        }
-        let sm = self.sess.source_map();
-        if !sm.is_multiline(prev_sp.until(sp)) {
-            // When the spans are in the same line, it means that the only content
-            // between them is whitespace, point only at the found token.
-            err.span_label(sp, label_exp);
-        } else {
-            err.span_label(prev_sp, label_exp);
-            err.span_label(sp, "unexpected token");
-        }
-        Err(err)
-    }
-
-    pub(super) fn expect_semi(&mut self) -> PResult<'a, ()> {
-        if self.eat(&token::Semi) {
-            return Ok(());
-        }
-        let sm = self.sess.source_map();
-        let msg = format!("expected `;`, found `{}`", self.this_token_descr());
-        let appl = Applicability::MachineApplicable;
-        if self.token.span == DUMMY_SP || self.prev_span == DUMMY_SP {
-            // Likely inside a macro, can't provide meaninful suggestions.
-            return self.expect(&token::Semi).map(|_| ());
-        } else if !sm.is_multiline(self.prev_span.until(self.token.span)) {
-            // The current token is in the same line as the prior token, not recoverable.
-        } else if self.look_ahead(1, |t| t == &token::CloseDelim(token::Brace)
-            || token_can_begin_expr(t) && t.kind != token::Colon
-        ) && [token::Comma, token::Colon].contains(&self.token.kind) {
-            // Likely typo: `,` → `;` or `:` → `;`. This is triggered if the current token is
-            // either `,` or `:`, and the next token could either start a new statement or is a
-            // block close. For example:
-            //
-            //   let x = 32:
-            //   let y = 42;
-            self.bump();
-            let sp = self.prev_span;
-            self.struct_span_err(sp, &msg)
-                .span_suggestion(sp, "change this to `;`", ";".to_string(), appl)
-                .emit();
-            return Ok(())
-        } else if self.look_ahead(0, |t| t == &token::CloseDelim(token::Brace) || (
-                token_can_begin_expr(t)
-                && t != &token::Semi
-                && t != &token::Pound // Avoid triggering with too many trailing `#` in raw string.
-        )) {
-            // Missing semicolon typo. This is triggered if the next token could either start a
-            // new statement or is a block close. For example:
-            //
-            //   let x = 32
-            //   let y = 42;
-            let sp = self.prev_span.shrink_to_hi();
-            self.struct_span_err(sp, &msg)
-                .span_label(self.token.span, "unexpected token")
-                .span_suggestion_short(sp, "add `;` here", ";".to_string(), appl)
-                .emit();
-            return Ok(())
-        }
-        self.expect(&token::Semi).map(|_| ()) // Error unconditionally
-    }
-
-    pub(super) fn parse_semi_or_incorrect_foreign_fn_body(
-        &mut self,
-        ident: &Ident,
-        extern_sp: Span,
-    ) -> PResult<'a, ()> {
-        if self.token != token::Semi {
-            // This might be an incorrect fn definition (#62109).
-            let parser_snapshot = self.clone();
-            match self.parse_inner_attrs_and_block() {
-                Ok((_, body)) => {
-                    self.struct_span_err(ident.span, "incorrect `fn` inside `extern` block")
-                        .span_label(ident.span, "can't have a body")
-                        .span_label(body.span, "this body is invalid here")
-                        .span_label(
-                            extern_sp,
-                            "`extern` blocks define existing foreign functions and `fn`s \
-                             inside of them cannot have a body")
-                        .help("you might have meant to write a function accessible through ffi, \
-                               which can be done by writing `extern fn` outside of the \
-                               `extern` block")
-                        .note("for more information, visit \
-                               https://doc.rust-lang.org/std/keyword.extern.html")
-                        .emit();
-                }
-                Err(mut err) => {
-                    err.cancel();
-                    mem::replace(self, parser_snapshot);
-                    self.expect_semi()?;
-                }
-            }
-        } else {
-            self.bump();
-        }
-        Ok(())
-    }
-
-    /// Consumes alternative await syntaxes like `await!(<expr>)`, `await <expr>`,
-    /// `await? <expr>`, `await(<expr>)`, and `await { <expr> }`.
-    pub(super) fn parse_incorrect_await_syntax(
-        &mut self,
-        lo: Span,
-        await_sp: Span,
-    ) -> PResult<'a, (Span, ExprKind)> {
-        if self.token == token::Not {
-            // Handle `await!(<expr>)`.
-            self.expect(&token::Not)?;
-            self.expect(&token::OpenDelim(token::Paren))?;
-            let expr = self.parse_expr()?;
-            self.expect(&token::CloseDelim(token::Paren))?;
-            let sp = self.error_on_incorrect_await(lo, self.prev_span, &expr, false);
-            return Ok((sp, ExprKind::Await(expr)))
-        }
-
-        let is_question = self.eat(&token::Question); // Handle `await? <expr>`.
-        let expr = if self.token == token::OpenDelim(token::Brace) {
-            // Handle `await { <expr> }`.
-            // This needs to be handled separatedly from the next arm to avoid
-            // interpreting `await { <expr> }?` as `<expr>?.await`.
-            self.parse_block_expr(
-                None,
-                self.token.span,
-                BlockCheckMode::Default,
-                ThinVec::new(),
-            )
-        } else {
-            self.parse_expr()
-        }.map_err(|mut err| {
-            err.span_label(await_sp, "while parsing this incorrect await expression");
-            err
-        })?;
-        let sp = self.error_on_incorrect_await(lo, expr.span, &expr, is_question);
-        Ok((sp, ExprKind::Await(expr)))
-    }
-
-    fn error_on_incorrect_await(&self, lo: Span, hi: Span, expr: &Expr, is_question: bool) -> Span {
-        let expr_str = self.span_to_snippet(expr.span)
-            .unwrap_or_else(|_| pprust::expr_to_string(&expr));
-        let suggestion = format!("{}.await{}", expr_str, if is_question { "?" } else { "" });
-        let sp = lo.to(hi);
-        let app = match expr.kind {
-            ExprKind::Try(_) => Applicability::MaybeIncorrect, // `await <expr>?`
-            _ => Applicability::MachineApplicable,
-        };
-        self.struct_span_err(sp, "incorrect use of `await`")
-            .span_suggestion(sp, "`await` is a postfix operation", suggestion, app)
-            .emit();
-        sp
-    }
-
-    /// If encountering `future.await()`, consumes and emits an error.
-    pub(super) fn recover_from_await_method_call(&mut self) {
-        if self.token == token::OpenDelim(token::Paren) &&
-            self.look_ahead(1, |t| t == &token::CloseDelim(token::Paren))
-        {
-            // future.await()
-            let lo = self.token.span;
-            self.bump(); // (
-            let sp = lo.to(self.token.span);
-            self.bump(); // )
-            self.struct_span_err(sp, "incorrect use of `await`")
-                .span_suggestion(
-                    sp,
-                    "`await` is not a method call, remove the parentheses",
-                    String::new(),
-                    Applicability::MachineApplicable,
-                ).emit()
-        }
-    }
-
-    /// Recovers a situation like `for ( $pat in $expr )`
-    /// and suggest writing `for $pat in $expr` instead.
-    ///
-    /// This should be called before parsing the `$block`.
-    pub(super) fn recover_parens_around_for_head(
-        &mut self,
-        pat: P<Pat>,
-        expr: &Expr,
-        begin_paren: Option<Span>,
-    ) -> P<Pat> {
-        match (&self.token.kind, begin_paren) {
-            (token::CloseDelim(token::Paren), Some(begin_par_sp)) => {
-                self.bump();
-
-                let pat_str = self
-                    // Remove the `(` from the span of the pattern:
-                    .span_to_snippet(pat.span.trim_start(begin_par_sp).unwrap())
-                    .unwrap_or_else(|_| pprust::pat_to_string(&pat));
-
-                self.struct_span_err(self.prev_span, "unexpected closing `)`")
-                    .span_label(begin_par_sp, "opening `(`")
-                    .span_suggestion(
-                        begin_par_sp.to(self.prev_span),
-                        "remove parenthesis in `for` loop",
-                        format!("{} in {}", pat_str, pprust::expr_to_string(&expr)),
-                        // With e.g. `for (x) in y)` this would replace `(x) in y)`
-                        // with `x) in y)` which is syntactically invalid.
-                        // However, this is prevented before we get here.
-                        Applicability::MachineApplicable,
-                    )
-                    .emit();
-
-                // Unwrap `(pat)` into `pat` to avoid the `unused_parens` lint.
-                pat.and_then(|pat| match pat.kind {
-                    PatKind::Paren(pat) => pat,
-                    _ => P(pat),
-                })
-            }
-            _ => pat,
-        }
-    }
-
-    pub(super) fn could_ascription_be_path(&self, node: &ast::ExprKind) -> bool {
-        (self.token == token::Lt && // `foo:<bar`, likely a typoed turbofish.
-            self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
-        ) ||
-            self.token.is_ident() &&
-            match node {
-                // `foo::` → `foo:` or `foo.bar::` → `foo.bar:`
-                ast::ExprKind::Path(..) | ast::ExprKind::Field(..) => true,
-                _ => false,
-            } &&
-            !self.token.is_reserved_ident() &&           // v `foo:bar(baz)`
-            self.look_ahead(1, |t| t == &token::OpenDelim(token::Paren)) ||
-            self.look_ahead(1, |t| t == &token::Lt) &&     // `foo:bar<baz`
-            self.look_ahead(2, |t| t.is_ident()) ||
-            self.look_ahead(1, |t| t == &token::Colon) &&  // `foo:bar:baz`
-            self.look_ahead(2, |t| t.is_ident()) ||
-            self.look_ahead(1, |t| t == &token::ModSep) &&
-            (self.look_ahead(2, |t| t.is_ident()) ||   // `foo:bar::baz`
-             self.look_ahead(2, |t| t == &token::Lt))  // `foo:bar::<baz>`
-    }
-
-    pub(super) fn recover_seq_parse_error(
-        &mut self,
-        delim: token::DelimToken,
-        lo: Span,
-        result: PResult<'a, P<Expr>>,
-    ) -> P<Expr> {
-        match result {
-            Ok(x) => x,
-            Err(mut err) => {
-                err.emit();
-                // Recover from parse error, callers expect the closing delim to be consumed.
-                self.consume_block(delim, ConsumeClosingDelim::Yes);
-                self.mk_expr(lo.to(self.prev_span), ExprKind::Err, ThinVec::new())
-            }
-        }
-    }
-
-    pub(super) fn recover_closing_delimiter(
-        &mut self,
-        tokens: &[TokenKind],
-        mut err: DiagnosticBuilder<'a>,
-    ) -> PResult<'a, bool> {
-        let mut pos = None;
-        // We want to use the last closing delim that would apply.
-        for (i, unmatched) in self.unclosed_delims.iter().enumerate().rev() {
-            if tokens.contains(&token::CloseDelim(unmatched.expected_delim))
-                && Some(self.token.span) > unmatched.unclosed_span
-            {
-                pos = Some(i);
-            }
-        }
-        match pos {
-            Some(pos) => {
-                // Recover and assume that the detected unclosed delimiter was meant for
-                // this location. Emit the diagnostic and act as if the delimiter was
-                // present for the parser's sake.
-
-                 // Don't attempt to recover from this unclosed delimiter more than once.
-                let unmatched = self.unclosed_delims.remove(pos);
-                let delim = TokenType::Token(token::CloseDelim(unmatched.expected_delim));
-                if unmatched.found_delim.is_none() {
-                    // We encountered `Eof`, set this fact here to avoid complaining about missing
-                    // `fn main()` when we found place to suggest the closing brace.
-                    *self.sess.reached_eof.borrow_mut() = true;
-                }
-
-                // We want to suggest the inclusion of the closing delimiter where it makes
-                // the most sense, which is immediately after the last token:
-                //
-                //  {foo(bar {}}
-                //      -      ^
-                //      |      |
-                //      |      help: `)` may belong here
-                //      |
-                //      unclosed delimiter
-                if let Some(sp) = unmatched.unclosed_span {
-                    err.span_label(sp, "unclosed delimiter");
-                }
-                err.span_suggestion_short(
-                    self.sess.source_map().next_point(self.prev_span),
-                    &format!("{} may belong here", delim.to_string()),
-                    delim.to_string(),
-                    Applicability::MaybeIncorrect,
-                );
-                if unmatched.found_delim.is_none() {
-                    // Encountered `Eof` when lexing blocks. Do not recover here to avoid knockdown
-                    // errors which would be emitted elsewhere in the parser and let other error
-                    // recovery consume the rest of the file.
-                    Err(err)
-                } else {
-                    err.emit();
-                    self.expected_tokens.clear();  // Reduce the number of errors.
-                    Ok(true)
-                }
-            }
-            _ => Err(err),
-        }
-    }
-
-    /// Recovers from `pub` keyword in places where it seems _reasonable_ but isn't valid.
-    pub(super) fn eat_bad_pub(&mut self) {
-        // When `unclosed_delims` is populated, it means that the code being parsed is already
-        // quite malformed, which might mean that, for example, a pub struct definition could be
-        // parsed as being a trait item, which is invalid and this error would trigger
-        // unconditionally, resulting in misleading diagnostics. Because of this, we only attempt
-        // this nice to have recovery for code that is otherwise well formed.
-        if self.token.is_keyword(kw::Pub) && self.unclosed_delims.is_empty() {
-            match self.parse_visibility(false) {
-                Ok(vis) => {
-                    self.diagnostic()
-                        .struct_span_err(vis.span, "unnecessary visibility qualifier")
-                        .span_label(vis.span, "`pub` not permitted here")
-                        .emit();
-                }
-                Err(mut err) => err.emit(),
-            }
-        }
-    }
-
-    /// Eats tokens until we can be relatively sure we reached the end of the
-    /// statement. This is something of a best-effort heuristic.
-    ///
-    /// We terminate when we find an unmatched `}` (without consuming it).
-    pub(super) fn recover_stmt(&mut self) {
-        self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore)
-    }
-
-    /// If `break_on_semi` is `Break`, then we will stop consuming tokens after
-    /// finding (and consuming) a `;` outside of `{}` or `[]` (note that this is
-    /// approximate -- it can mean we break too early due to macros, but that
-    /// should only lead to sub-optimal recovery, not inaccurate parsing).
-    ///
-    /// If `break_on_block` is `Break`, then we will stop consuming tokens
-    /// after finding (and consuming) a brace-delimited block.
-    pub(super) fn recover_stmt_(
-        &mut self,
-        break_on_semi: SemiColonMode,
-        break_on_block: BlockMode,
-    ) {
-        let mut brace_depth = 0;
-        let mut bracket_depth = 0;
-        let mut in_block = false;
-        debug!("recover_stmt_ enter loop (semi={:?}, block={:?})",
-               break_on_semi, break_on_block);
-        loop {
-            debug!("recover_stmt_ loop {:?}", self.token);
-            match self.token.kind {
-                token::OpenDelim(token::DelimToken::Brace) => {
-                    brace_depth += 1;
-                    self.bump();
-                    if break_on_block == BlockMode::Break &&
-                       brace_depth == 1 &&
-                       bracket_depth == 0 {
-                        in_block = true;
-                    }
-                }
-                token::OpenDelim(token::DelimToken::Bracket) => {
-                    bracket_depth += 1;
-                    self.bump();
-                }
-                token::CloseDelim(token::DelimToken::Brace) => {
-                    if brace_depth == 0 {
-                        debug!("recover_stmt_ return - close delim {:?}", self.token);
-                        break;
-                    }
-                    brace_depth -= 1;
-                    self.bump();
-                    if in_block && bracket_depth == 0 && brace_depth == 0 {
-                        debug!("recover_stmt_ return - block end {:?}", self.token);
-                        break;
-                    }
-                }
-                token::CloseDelim(token::DelimToken::Bracket) => {
-                    bracket_depth -= 1;
-                    if bracket_depth < 0 {
-                        bracket_depth = 0;
-                    }
-                    self.bump();
-                }
-                token::Eof => {
-                    debug!("recover_stmt_ return - Eof");
-                    break;
-                }
-                token::Semi => {
-                    self.bump();
-                    if break_on_semi == SemiColonMode::Break &&
-                       brace_depth == 0 &&
-                       bracket_depth == 0 {
-                        debug!("recover_stmt_ return - Semi");
-                        break;
-                    }
-                }
-                token::Comma if break_on_semi == SemiColonMode::Comma &&
-                       brace_depth == 0 &&
-                       bracket_depth == 0 =>
-                {
-                    debug!("recover_stmt_ return - Semi");
-                    break;
-                }
-                _ => {
-                    self.bump()
-                }
-            }
-        }
-    }
-
-    pub(super) fn check_for_for_in_in_typo(&mut self, in_span: Span) {
-        if self.eat_keyword(kw::In) {
-            // a common typo: `for _ in in bar {}`
-            self.struct_span_err(self.prev_span, "expected iterable, found keyword `in`")
-                .span_suggestion_short(
-                    in_span.until(self.prev_span),
-                    "remove the duplicated `in`",
-                    String::new(),
-                    Applicability::MachineApplicable,
-                )
-                .emit();
-        }
-    }
-
-    pub(super) fn expected_semi_or_open_brace<T>(&mut self) -> PResult<'a, T> {
-        let token_str = self.this_token_descr();
-        let mut err = self.fatal(&format!("expected `;` or `{{`, found {}", token_str));
-        err.span_label(self.token.span, "expected `;` or `{`");
-        Err(err)
-    }
-
-    pub(super) fn eat_incorrect_doc_comment_for_param_type(&mut self) {
-        if let token::DocComment(_) = self.token.kind {
-            self.struct_span_err(
-                self.token.span,
-                "documentation comments cannot be applied to a function parameter's type",
-            )
-            .span_label(self.token.span, "doc comments are not allowed here")
-            .emit();
-            self.bump();
-        } else if self.token == token::Pound && self.look_ahead(1, |t| {
-            *t == token::OpenDelim(token::Bracket)
-        }) {
-            let lo = self.token.span;
-            // Skip every token until next possible arg.
-            while self.token != token::CloseDelim(token::Bracket) {
-                self.bump();
-            }
-            let sp = lo.to(self.token.span);
-            self.bump();
-            self.struct_span_err(
-                sp,
-                "attributes cannot be applied to a function parameter's type",
-            )
-            .span_label(sp, "attributes are not allowed here")
-            .emit();
-        }
-    }
-
-    pub(super) fn parameter_without_type(
-        &mut self,
-        err: &mut DiagnosticBuilder<'_>,
-        pat: P<ast::Pat>,
-        require_name: bool,
-        is_self_allowed: bool,
-        is_trait_item: bool,
-    ) -> Option<Ident> {
-        // If we find a pattern followed by an identifier, it could be an (incorrect)
-        // C-style parameter declaration.
-        if self.check_ident() && self.look_ahead(1, |t| {
-            *t == token::Comma || *t == token::CloseDelim(token::Paren)
-        }) { // `fn foo(String s) {}`
-            let ident = self.parse_ident().unwrap();
-            let span = pat.span.with_hi(ident.span.hi());
-
-            err.span_suggestion(
-                span,
-                "declare the type after the parameter binding",
-                String::from("<identifier>: <type>"),
-                Applicability::HasPlaceholders,
-            );
-            return Some(ident);
-        } else if let PatKind::Ident(_, ident, _) = pat.kind {
-            if require_name && (
-                is_trait_item ||
-                self.token == token::Comma ||
-                self.token == token::Lt ||
-                self.token == token::CloseDelim(token::Paren)
-            ) { // `fn foo(a, b) {}`, `fn foo(a<x>, b<y>) {}` or `fn foo(usize, usize) {}`
-                if is_self_allowed {
-                    err.span_suggestion(
-                        pat.span,
-                        "if this is a `self` type, give it a parameter name",
-                        format!("self: {}", ident),
-                        Applicability::MaybeIncorrect,
-                    );
-                }
-                // Avoid suggesting that `fn foo(HashMap<u32>)` is fixed with a change to
-                // `fn foo(HashMap: TypeName<u32>)`.
-                if self.token != token::Lt {
-                    err.span_suggestion(
-                        pat.span,
-                        "if this was a parameter name, give it a type",
-                        format!("{}: TypeName", ident),
-                        Applicability::HasPlaceholders,
-                    );
-                }
-                err.span_suggestion(
-                    pat.span,
-                    "if this is a type, explicitly ignore the parameter name",
-                    format!("_: {}", ident),
-                    Applicability::MachineApplicable,
-                );
-                err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)");
-
-                // Don't attempt to recover by using the `X` in `X<Y>` as the parameter name.
-                return if self.token == token::Lt { None } else { Some(ident) };
-            }
-        }
-        None
-    }
-
-    pub(super) fn recover_arg_parse(&mut self) -> PResult<'a, (P<ast::Pat>, P<ast::Ty>)> {
-        let pat = self.parse_pat(Some("argument name"))?;
-        self.expect(&token::Colon)?;
-        let ty = self.parse_ty()?;
-
-        self.diagnostic()
-            .struct_span_err_with_code(
-                pat.span,
-                "patterns aren't allowed in methods without bodies",
-                DiagnosticId::Error("E0642".into()),
-            )
-            .span_suggestion_short(
-                pat.span,
-                "give this argument a name or use an underscore to ignore it",
-                "_".to_owned(),
-                Applicability::MachineApplicable,
-            )
-            .emit();
-
-        // Pretend the pattern is `_`, to avoid duplicate errors from AST validation.
-        let pat = P(Pat {
-            kind: PatKind::Wild,
-            span: pat.span,
-            id: ast::DUMMY_NODE_ID
-        });
-        Ok((pat, ty))
-    }
-
-    pub(super) fn recover_bad_self_param(
-        &mut self,
-        mut param: ast::Param,
-        is_trait_item: bool,
-    ) -> PResult<'a, ast::Param> {
-        let sp = param.pat.span;
-        param.ty.kind = TyKind::Err;
-        let mut err = self.struct_span_err(sp, "unexpected `self` parameter in function");
-        if is_trait_item {
-            err.span_label(sp, "must be the first associated function parameter");
-        } else {
-            err.span_label(sp, "not valid as function parameter");
-            err.note("`self` is only valid as the first parameter of an associated function");
-        }
-        err.emit();
-        Ok(param)
-    }
-
-    pub(super) fn consume_block(
-        &mut self,
-        delim: token::DelimToken,
-        consume_close: ConsumeClosingDelim,
-    ) {
-        let mut brace_depth = 0;
-        loop {
-            if self.eat(&token::OpenDelim(delim)) {
-                brace_depth += 1;
-            } else if self.check(&token::CloseDelim(delim)) {
-                if brace_depth == 0 {
-                    if let ConsumeClosingDelim::Yes = consume_close {
-                        // Some of the callers of this method expect to be able to parse the
-                        // closing delimiter themselves, so we leave it alone. Otherwise we advance
-                        // the parser.
-                        self.bump();
-                    }
-                    return;
-                } else {
-                    self.bump();
-                    brace_depth -= 1;
-                    continue;
-                }
-            } else if self.token == token::Eof || self.eat(&token::CloseDelim(token::NoDelim)) {
-                return;
-            } else {
-                self.bump();
-            }
-        }
-    }
-
-    pub(super) fn expected_expression_found(&self) -> DiagnosticBuilder<'a> {
-        let (span, msg) = match (&self.token.kind, self.subparser_name) {
-            (&token::Eof, Some(origin)) => {
-                let sp = self.sess.source_map().next_point(self.token.span);
-                (sp, format!("expected expression, found end of {}", origin))
-            }
-            _ => (self.token.span, format!(
-                "expected expression, found {}",
-                self.this_token_descr(),
-            )),
-        };
-        let mut err = self.struct_span_err(span, &msg);
-        let sp = self.sess.source_map().start_point(self.token.span);
-        if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow().get(&sp) {
-            self.sess.expr_parentheses_needed(&mut err, *sp, None);
-        }
-        err.span_label(span, "expected expression");
-        err
-    }
-
-    fn consume_tts(
-        &mut self,
-        mut acc: i64, // `i64` because malformed code can have more closing delims than opening.
-        // Not using `FxHashMap` due to `token::TokenKind: !Eq + !Hash`.
-        modifier: &[(token::TokenKind, i64)],
-    ) {
-        while acc > 0 {
-            if let Some((_, val)) = modifier.iter().find(|(t, _)| *t == self.token.kind) {
-                acc += *val;
-            }
-            if self.token.kind == token::Eof {
-                break;
-            }
-            self.bump();
-        }
-    }
-
-    /// Replace duplicated recovered parameters with `_` pattern to avoid unecessary errors.
-    ///
-    /// This is necessary because at this point we don't know whether we parsed a function with
-    /// anonymous parameters or a function with names but no types. In order to minimize
-    /// unecessary errors, we assume the parameters are in the shape of `fn foo(a, b, c)` where
-    /// the parameters are *names* (so we don't emit errors about not being able to find `b` in
-    /// the local scope), but if we find the same name multiple times, like in `fn foo(i8, i8)`,
-    /// we deduplicate them to not complain about duplicated parameter names.
-    pub(super) fn deduplicate_recovered_params_names(&self, fn_inputs: &mut Vec<Param>) {
-        let mut seen_inputs = FxHashSet::default();
-        for input in fn_inputs.iter_mut() {
-            let opt_ident = if let (PatKind::Ident(_, ident, _), TyKind::Err) = (
-                &input.pat.kind, &input.ty.kind,
-            ) {
-                Some(*ident)
-            } else {
-                None
-            };
-            if let Some(ident) = opt_ident {
-                if seen_inputs.contains(&ident) {
-                    input.pat.kind = PatKind::Wild;
-                }
-                seen_inputs.insert(ident);
-            }
-        }
-    }
-}
diff --git a/src/libsyntax/parse/parser/expr.rs b/src/libsyntax/parse/parser/expr.rs
deleted file mode 100644
index 800074035ce..00000000000
--- a/src/libsyntax/parse/parser/expr.rs
+++ /dev/null
@@ -1,1964 +0,0 @@
-use super::{Parser, Restrictions, PrevTokenKind, TokenType, PathStyle, BlockMode};
-use super::{SemiColonMode, SeqSep, TokenExpectType};
-use super::pat::{GateOr, PARAM_EXPECTED};
-use super::diagnostics::Error;
-
-use crate::ast::{
-    self, DUMMY_NODE_ID, Attribute, AttrStyle, Ident, CaptureBy, BlockCheckMode,
-    Expr, ExprKind, RangeLimits, Label, Movability, IsAsync, Arm, Ty, TyKind,
-    FunctionRetTy, Param, FnDecl, BinOpKind, BinOp, UnOp, Mac, AnonConst, Field, Lit,
-};
-use crate::maybe_recover_from_interpolated_ty_qpath;
-use crate::token::{self, Token, TokenKind};
-use crate::print::pprust;
-use crate::ptr::P;
-use crate::source_map::{self, Span};
-use crate::util::classify;
-use crate::util::literal::LitError;
-use crate::util::parser::{AssocOp, Fixity, prec_let_scrutinee_needs_par};
-
-use errors::{PResult, Applicability};
-use syntax_pos::symbol::{kw, sym};
-use syntax_pos::Symbol;
-use std::mem;
-use rustc_data_structures::thin_vec::ThinVec;
-
-/// Possibly accepts an `token::Interpolated` expression (a pre-parsed expression
-/// dropped into the token stream, which happens while parsing the result of
-/// macro expansion). Placement of these is not as complex as I feared it would
-/// be. The important thing is to make sure that lookahead doesn't balk at
-/// `token::Interpolated` tokens.
-macro_rules! maybe_whole_expr {
-    ($p:expr) => {
-        if let token::Interpolated(nt) = &$p.token.kind {
-            match &**nt {
-                token::NtExpr(e) | token::NtLiteral(e) => {
-                    let e = e.clone();
-                    $p.bump();
-                    return Ok(e);
-                }
-                token::NtPath(path) => {
-                    let path = path.clone();
-                    $p.bump();
-                    return Ok($p.mk_expr(
-                        $p.token.span, ExprKind::Path(None, path), ThinVec::new()
-                    ));
-                }
-                token::NtBlock(block) => {
-                    let block = block.clone();
-                    $p.bump();
-                    return Ok($p.mk_expr(
-                        $p.token.span, ExprKind::Block(block, None), ThinVec::new()
-                    ));
-                }
-                // N.B., `NtIdent(ident)` is normalized to `Ident` in `fn bump`.
-                _ => {},
-            };
-        }
-    }
-}
-
-#[derive(Debug)]
-pub(super) enum LhsExpr {
-    NotYetParsed,
-    AttributesParsed(ThinVec<Attribute>),
-    AlreadyParsed(P<Expr>),
-}
-
-impl From<Option<ThinVec<Attribute>>> for LhsExpr {
-    /// Converts `Some(attrs)` into `LhsExpr::AttributesParsed(attrs)`
-    /// and `None` into `LhsExpr::NotYetParsed`.
-    ///
-    /// This conversion does not allocate.
-    fn from(o: Option<ThinVec<Attribute>>) -> Self {
-        if let Some(attrs) = o {
-            LhsExpr::AttributesParsed(attrs)
-        } else {
-            LhsExpr::NotYetParsed
-        }
-    }
-}
-
-impl From<P<Expr>> for LhsExpr {
-    /// Converts the `expr: P<Expr>` into `LhsExpr::AlreadyParsed(expr)`.
-    ///
-    /// This conversion does not allocate.
-    fn from(expr: P<Expr>) -> Self {
-        LhsExpr::AlreadyParsed(expr)
-    }
-}
-
-impl<'a> Parser<'a> {
-    /// Parses an expression.
-    #[inline]
-    pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
-        self.parse_expr_res(Restrictions::empty(), None)
-    }
-
-    fn parse_paren_expr_seq(&mut self) -> PResult<'a, Vec<P<Expr>>> {
-        self.parse_paren_comma_seq(|p| {
-            match p.parse_expr() {
-                Ok(expr) => Ok(expr),
-                Err(mut err) => match p.token.kind {
-                    token::Ident(name, false)
-                    if name == kw::Underscore && p.look_ahead(1, |t| {
-                        t == &token::Comma
-                    }) => {
-                        // Special-case handling of `foo(_, _, _)`
-                        err.emit();
-                        let sp = p.token.span;
-                        p.bump();
-                        Ok(p.mk_expr(sp, ExprKind::Err, ThinVec::new()))
-                    }
-                    _ => Err(err),
-                },
-            }
-        }).map(|(r, _)| r)
-    }
-
-    /// Parses an expression, subject to the given restrictions.
-    #[inline]
-    pub(super) fn parse_expr_res(
-        &mut self,
-        r: Restrictions,
-        already_parsed_attrs: Option<ThinVec<Attribute>>
-    ) -> PResult<'a, P<Expr>> {
-        self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs))
-    }
-
-    /// Parses an associative expression.
-    ///
-    /// This parses an expression accounting for associativity and precedence of the operators in
-    /// the expression.
-    #[inline]
-    fn parse_assoc_expr(
-        &mut self,
-        already_parsed_attrs: Option<ThinVec<Attribute>>,
-    ) -> PResult<'a, P<Expr>> {
-        self.parse_assoc_expr_with(0, already_parsed_attrs.into())
-    }
-
-    /// Parses an associative expression with operators of at least `min_prec` precedence.
-    pub(super) fn parse_assoc_expr_with(
-        &mut self,
-        min_prec: usize,
-        lhs: LhsExpr,
-    ) -> PResult<'a, P<Expr>> {
-        let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs {
-            expr
-        } else {
-            let attrs = match lhs {
-                LhsExpr::AttributesParsed(attrs) => Some(attrs),
-                _ => None,
-            };
-            if [token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token.kind) {
-                return self.parse_prefix_range_expr(attrs);
-            } else {
-                self.parse_prefix_expr(attrs)?
-            }
-        };
-        let last_type_ascription_set = self.last_type_ascription.is_some();
-
-        match (self.expr_is_complete(&lhs), AssocOp::from_token(&self.token)) {
-            (true, None) => {
-                self.last_type_ascription = None;
-                // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
-                return Ok(lhs);
-            }
-            (false, _) => {} // continue parsing the expression
-            // An exhaustive check is done in the following block, but these are checked first
-            // because they *are* ambiguous but also reasonable looking incorrect syntax, so we
-            // want to keep their span info to improve diagnostics in these cases in a later stage.
-            (true, Some(AssocOp::Multiply)) | // `{ 42 } *foo = bar;` or `{ 42 } * 3`
-            (true, Some(AssocOp::Subtract)) | // `{ 42 } -5`
-            (true, Some(AssocOp::LAnd)) | // `{ 42 } &&x` (#61475)
-            (true, Some(AssocOp::Add)) // `{ 42 } + 42
-            // If the next token is a keyword, then the tokens above *are* unambiguously incorrect:
-            // `if x { a } else { b } && if y { c } else { d }`
-            if !self.look_ahead(1, |t| t.is_reserved_ident()) => {
-                self.last_type_ascription = None;
-                // These cases are ambiguous and can't be identified in the parser alone
-                let sp = self.sess.source_map().start_point(self.token.span);
-                self.sess.ambiguous_block_expr_parse.borrow_mut().insert(sp, lhs.span);
-                return Ok(lhs);
-            }
-            (true, Some(ref op)) if !op.can_continue_expr_unambiguously() => {
-                self.last_type_ascription = None;
-                return Ok(lhs);
-            }
-            (true, Some(_)) => {
-                // We've found an expression that would be parsed as a statement, but the next
-                // token implies this should be parsed as an expression.
-                // For example: `if let Some(x) = x { x } else { 0 } / 2`
-                let mut err = self.struct_span_err(self.token.span, &format!(
-                    "expected expression, found `{}`",
-                    pprust::token_to_string(&self.token),
-                ));
-                err.span_label(self.token.span, "expected expression");
-                self.sess.expr_parentheses_needed(
-                    &mut err,
-                    lhs.span,
-                    Some(pprust::expr_to_string(&lhs),
-                ));
-                err.emit();
-            }
-        }
-        self.expected_tokens.push(TokenType::Operator);
-        while let Some(op) = AssocOp::from_token(&self.token) {
-
-            // Adjust the span for interpolated LHS to point to the `$lhs` token and not to what
-            // it refers to. Interpolated identifiers are unwrapped early and never show up here
-            // as `PrevTokenKind::Interpolated` so if LHS is a single identifier we always process
-            // it as "interpolated", it doesn't change the answer for non-interpolated idents.
-            let lhs_span = match (self.prev_token_kind, &lhs.kind) {
-                (PrevTokenKind::Interpolated, _) => self.prev_span,
-                (PrevTokenKind::Ident, &ExprKind::Path(None, ref path))
-                    if path.segments.len() == 1 => self.prev_span,
-                _ => lhs.span,
-            };
-
-            let cur_op_span = self.token.span;
-            let restrictions = if op.is_assign_like() {
-                self.restrictions & Restrictions::NO_STRUCT_LITERAL
-            } else {
-                self.restrictions
-            };
-            let prec = op.precedence();
-            if prec < min_prec {
-                break;
-            }
-            // Check for deprecated `...` syntax
-            if self.token == token::DotDotDot && op == AssocOp::DotDotEq {
-                self.err_dotdotdot_syntax(self.token.span);
-            }
-
-            if self.token == token::LArrow {
-                self.err_larrow_operator(self.token.span);
-            }
-
-            self.bump();
-            if op.is_comparison() {
-                if let Some(expr) = self.check_no_chained_comparison(&lhs, &op)? {
-                    return Ok(expr);
-                }
-            }
-            // Special cases:
-            if op == AssocOp::As {
-                lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Cast)?;
-                continue
-            } else if op == AssocOp::Colon {
-                let maybe_path = self.could_ascription_be_path(&lhs.kind);
-                self.last_type_ascription = Some((self.prev_span, maybe_path));
-
-                lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Type)?;
-                self.sess.gated_spans.gate(sym::type_ascription, lhs.span);
-                continue
-            } else if op == AssocOp::DotDot || op == AssocOp::DotDotEq {
-                // If we didn’t have to handle `x..`/`x..=`, it would be pretty easy to
-                // generalise it to the Fixity::None code.
-                //
-                // We have 2 alternatives here: `x..y`/`x..=y` and `x..`/`x..=` The other
-                // two variants are handled with `parse_prefix_range_expr` call above.
-                let rhs = if self.is_at_start_of_range_notation_rhs() {
-                    Some(self.parse_assoc_expr_with(prec + 1, LhsExpr::NotYetParsed)?)
-                } else {
-                    None
-                };
-                let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs {
-                    x.span
-                } else {
-                    cur_op_span
-                });
-                let limits = if op == AssocOp::DotDot {
-                    RangeLimits::HalfOpen
-                } else {
-                    RangeLimits::Closed
-                };
-
-                let r = self.mk_range(Some(lhs), rhs, limits)?;
-                lhs = self.mk_expr(lhs_span.to(rhs_span), r, ThinVec::new());
-                break
-            }
-
-            let fixity = op.fixity();
-            let prec_adjustment = match fixity {
-                Fixity::Right => 0,
-                Fixity::Left => 1,
-                // We currently have no non-associative operators that are not handled above by
-                // the special cases. The code is here only for future convenience.
-                Fixity::None => 1,
-            };
-            let rhs = self.with_res(
-                restrictions - Restrictions::STMT_EXPR,
-                |this| this.parse_assoc_expr_with(prec + prec_adjustment, LhsExpr::NotYetParsed)
-            )?;
-
-            // Make sure that the span of the parent node is larger than the span of lhs and rhs,
-            // including the attributes.
-            let lhs_span = lhs
-                .attrs
-                .iter()
-                .filter(|a| a.style == AttrStyle::Outer)
-                .next()
-                .map_or(lhs_span, |a| a.span);
-            let span = lhs_span.to(rhs.span);
-            lhs = match op {
-                AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |
-                AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor |
-                AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight |
-                AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual |
-                AssocOp::Greater | AssocOp::GreaterEqual => {
-                    let ast_op = op.to_ast_binop().unwrap();
-                    let binary = self.mk_binary(source_map::respan(cur_op_span, ast_op), lhs, rhs);
-                    self.mk_expr(span, binary, ThinVec::new())
-                }
-                AssocOp::Assign => self.mk_expr(span, ExprKind::Assign(lhs, rhs), ThinVec::new()),
-                AssocOp::AssignOp(k) => {
-                    let aop = match k {
-                        token::Plus =>    BinOpKind::Add,
-                        token::Minus =>   BinOpKind::Sub,
-                        token::Star =>    BinOpKind::Mul,
-                        token::Slash =>   BinOpKind::Div,
-                        token::Percent => BinOpKind::Rem,
-                        token::Caret =>   BinOpKind::BitXor,
-                        token::And =>     BinOpKind::BitAnd,
-                        token::Or =>      BinOpKind::BitOr,
-                        token::Shl =>     BinOpKind::Shl,
-                        token::Shr =>     BinOpKind::Shr,
-                    };
-                    let aopexpr = self.mk_assign_op(source_map::respan(cur_op_span, aop), lhs, rhs);
-                    self.mk_expr(span, aopexpr, ThinVec::new())
-                }
-                AssocOp::As | AssocOp::Colon | AssocOp::DotDot | AssocOp::DotDotEq => {
-                    self.bug("AssocOp should have been handled by special case")
-                }
-            };
-
-            if let Fixity::None = fixity { break }
-        }
-        if last_type_ascription_set {
-            self.last_type_ascription = None;
-        }
-        Ok(lhs)
-    }
-
-    /// Checks if this expression is a successfully parsed statement.
-    fn expr_is_complete(&self, e: &Expr) -> bool {
-        self.restrictions.contains(Restrictions::STMT_EXPR) &&
-            !classify::expr_requires_semi_to_be_stmt(e)
-    }
-
-    fn is_at_start_of_range_notation_rhs(&self) -> bool {
-        if self.token.can_begin_expr() {
-            // Parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
-            if self.token == token::OpenDelim(token::Brace) {
-                return !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
-            }
-            true
-        } else {
-            false
-        }
-    }
-
-    /// Parses prefix-forms of range notation: `..expr`, `..`, `..=expr`.
-    fn parse_prefix_range_expr(
-        &mut self,
-        already_parsed_attrs: Option<ThinVec<Attribute>>
-    ) -> PResult<'a, P<Expr>> {
-        // Check for deprecated `...` syntax.
-        if self.token == token::DotDotDot {
-            self.err_dotdotdot_syntax(self.token.span);
-        }
-
-        debug_assert!([token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token.kind),
-                      "parse_prefix_range_expr: token {:?} is not DotDot/DotDotEq",
-                      self.token);
-        let tok = self.token.clone();
-        let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
-        let lo = self.token.span;
-        let mut hi = self.token.span;
-        self.bump();
-        let opt_end = if self.is_at_start_of_range_notation_rhs() {
-            // RHS must be parsed with more associativity than the dots.
-            let next_prec = AssocOp::from_token(&tok).unwrap().precedence() + 1;
-            Some(self.parse_assoc_expr_with(next_prec, LhsExpr::NotYetParsed)
-                .map(|x| {
-                    hi = x.span;
-                    x
-                })?)
-        } else {
-            None
-        };
-        let limits = if tok == token::DotDot {
-            RangeLimits::HalfOpen
-        } else {
-            RangeLimits::Closed
-        };
-
-        let r = self.mk_range(None, opt_end, limits)?;
-        Ok(self.mk_expr(lo.to(hi), r, attrs))
-    }
-
-    /// Parses a prefix-unary-operator expr.
-    fn parse_prefix_expr(
-        &mut self,
-        already_parsed_attrs: Option<ThinVec<Attribute>>
-    ) -> PResult<'a, P<Expr>> {
-        let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
-        let lo = self.token.span;
-        // Note: when adding new unary operators, don't forget to adjust TokenKind::can_begin_expr()
-        let (hi, ex) = match self.token.kind {
-            token::Not => {
-                self.bump();
-                let e = self.parse_prefix_expr(None);
-                let (span, e) = self.interpolated_or_expr_span(e)?;
-                (lo.to(span), self.mk_unary(UnOp::Not, e))
-            }
-            // Suggest `!` for bitwise negation when encountering a `~`
-            token::Tilde => {
-                self.bump();
-                let e = self.parse_prefix_expr(None);
-                let (span, e) = self.interpolated_or_expr_span(e)?;
-                let span_of_tilde = lo;
-                self.struct_span_err(span_of_tilde, "`~` cannot be used as a unary operator")
-                    .span_suggestion_short(
-                        span_of_tilde,
-                        "use `!` to perform bitwise not",
-                        "!".to_owned(),
-                        Applicability::MachineApplicable
-                    )
-                    .emit();
-                (lo.to(span), self.mk_unary(UnOp::Not, e))
-            }
-            token::BinOp(token::Minus) => {
-                self.bump();
-                let e = self.parse_prefix_expr(None);
-                let (span, e) = self.interpolated_or_expr_span(e)?;
-                (lo.to(span), self.mk_unary(UnOp::Neg, e))
-            }
-            token::BinOp(token::Star) => {
-                self.bump();
-                let e = self.parse_prefix_expr(None);
-                let (span, e) = self.interpolated_or_expr_span(e)?;
-                (lo.to(span), self.mk_unary(UnOp::Deref, e))
-            }
-            token::BinOp(token::And) | token::AndAnd => {
-                self.expect_and()?;
-                let m = self.parse_mutability();
-                let e = self.parse_prefix_expr(None);
-                let (span, e) = self.interpolated_or_expr_span(e)?;
-                (lo.to(span), ExprKind::AddrOf(m, e))
-            }
-            token::Ident(..) if self.token.is_keyword(kw::Box) => {
-                self.bump();
-                let e = self.parse_prefix_expr(None);
-                let (span, e) = self.interpolated_or_expr_span(e)?;
-                let span = lo.to(span);
-                self.sess.gated_spans.gate(sym::box_syntax, span);
-                (span, ExprKind::Box(e))
-            }
-            token::Ident(..) if self.token.is_ident_named(sym::not) => {
-                // `not` is just an ordinary identifier in Rust-the-language,
-                // but as `rustc`-the-compiler, we can issue clever diagnostics
-                // for confused users who really want to say `!`
-                let token_cannot_continue_expr = |t: &Token| match t.kind {
-                    // These tokens can start an expression after `!`, but
-                    // can't continue an expression after an ident
-                    token::Ident(name, is_raw) => token::ident_can_begin_expr(name, t.span, is_raw),
-                    token::Literal(..) | token::Pound => true,
-                    _ => t.is_whole_expr(),
-                };
-                let cannot_continue_expr = self.look_ahead(1, token_cannot_continue_expr);
-                if cannot_continue_expr {
-                    self.bump();
-                    // Emit the error ...
-                    self.struct_span_err(
-                        self.token.span,
-                        &format!("unexpected {} after identifier",self.this_token_descr())
-                    )
-                    .span_suggestion_short(
-                        // Span the `not` plus trailing whitespace to avoid
-                        // trailing whitespace after the `!` in our suggestion
-                        self.sess.source_map()
-                            .span_until_non_whitespace(lo.to(self.token.span)),
-                        "use `!` to perform logical negation",
-                        "!".to_owned(),
-                        Applicability::MachineApplicable
-                    )
-                    .emit();
-                    // —and recover! (just as if we were in the block
-                    // for the `token::Not` arm)
-                    let e = self.parse_prefix_expr(None);
-                    let (span, e) = self.interpolated_or_expr_span(e)?;
-                    (lo.to(span), self.mk_unary(UnOp::Not, e))
-                } else {
-                    return self.parse_dot_or_call_expr(Some(attrs));
-                }
-            }
-            _ => { return self.parse_dot_or_call_expr(Some(attrs)); }
-        };
-        return Ok(self.mk_expr(lo.to(hi), ex, attrs));
-    }
-
-    /// Returns the span of expr, if it was not interpolated or the span of the interpolated token.
-    fn interpolated_or_expr_span(
-        &self,
-        expr: PResult<'a, P<Expr>>,
-    ) -> PResult<'a, (Span, P<Expr>)> {
-        expr.map(|e| {
-            if self.prev_token_kind == PrevTokenKind::Interpolated {
-                (self.prev_span, e)
-            } else {
-                (e.span, e)
-            }
-        })
-    }
-
-    fn parse_assoc_op_cast(&mut self, lhs: P<Expr>, lhs_span: Span,
-                           expr_kind: fn(P<Expr>, P<Ty>) -> ExprKind)
-                           -> PResult<'a, P<Expr>> {
-        let mk_expr = |this: &mut Self, rhs: P<Ty>| {
-            this.mk_expr(lhs_span.to(rhs.span), expr_kind(lhs, rhs), ThinVec::new())
-        };
-
-        // Save the state of the parser before parsing type normally, in case there is a
-        // LessThan comparison after this cast.
-        let parser_snapshot_before_type = self.clone();
-        match self.parse_ty_no_plus() {
-            Ok(rhs) => {
-                Ok(mk_expr(self, rhs))
-            }
-            Err(mut type_err) => {
-                // Rewind to before attempting to parse the type with generics, to recover
-                // from situations like `x as usize < y` in which we first tried to parse
-                // `usize < y` as a type with generic arguments.
-                let parser_snapshot_after_type = self.clone();
-                mem::replace(self, parser_snapshot_before_type);
-
-                match self.parse_path(PathStyle::Expr) {
-                    Ok(path) => {
-                        let (op_noun, op_verb) = match self.token.kind {
-                            token::Lt => ("comparison", "comparing"),
-                            token::BinOp(token::Shl) => ("shift", "shifting"),
-                            _ => {
-                                // We can end up here even without `<` being the next token, for
-                                // example because `parse_ty_no_plus` returns `Err` on keywords,
-                                // but `parse_path` returns `Ok` on them due to error recovery.
-                                // Return original error and parser state.
-                                mem::replace(self, parser_snapshot_after_type);
-                                return Err(type_err);
-                            }
-                        };
-
-                        // Successfully parsed the type path leaving a `<` yet to parse.
-                        type_err.cancel();
-
-                        // Report non-fatal diagnostics, keep `x as usize` as an expression
-                        // in AST and continue parsing.
-                        let msg = format!(
-                            "`<` is interpreted as a start of generic arguments for `{}`, not a {}",
-                            pprust::path_to_string(&path),
-                            op_noun,
-                        );
-                        let span_after_type = parser_snapshot_after_type.token.span;
-                        let expr = mk_expr(self, P(Ty {
-                            span: path.span,
-                            kind: TyKind::Path(None, path),
-                            id: DUMMY_NODE_ID,
-                        }));
-
-                        let expr_str = self.span_to_snippet(expr.span)
-                            .unwrap_or_else(|_| pprust::expr_to_string(&expr));
-
-                        self.struct_span_err(self.token.span, &msg)
-                            .span_label(
-                                self.look_ahead(1, |t| t.span).to(span_after_type),
-                                "interpreted as generic arguments"
-                            )
-                            .span_label(self.token.span, format!("not interpreted as {}", op_noun))
-                            .span_suggestion(
-                                expr.span,
-                                &format!("try {} the cast value", op_verb),
-                                format!("({})", expr_str),
-                                Applicability::MachineApplicable,
-                            )
-                            .emit();
-
-                        Ok(expr)
-                    }
-                    Err(mut path_err) => {
-                        // Couldn't parse as a path, return original error and parser state.
-                        path_err.cancel();
-                        mem::replace(self, parser_snapshot_after_type);
-                        Err(type_err)
-                    }
-                }
-            }
-        }
-    }
-
-    /// Parses `a.b` or `a(13)` or `a[4]` or just `a`.
-    fn parse_dot_or_call_expr(
-        &mut self,
-        already_parsed_attrs: Option<ThinVec<Attribute>>,
-    ) -> PResult<'a, P<Expr>> {
-        let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
-
-        let b = self.parse_bottom_expr();
-        let (span, b) = self.interpolated_or_expr_span(b)?;
-        self.parse_dot_or_call_expr_with(b, span, attrs)
-    }
-
-    pub(super) fn parse_dot_or_call_expr_with(
-        &mut self,
-        e0: P<Expr>,
-        lo: Span,
-        mut attrs: ThinVec<Attribute>,
-    ) -> PResult<'a, P<Expr>> {
-        // Stitch the list of outer attributes onto the return value.
-        // A little bit ugly, but the best way given the current code
-        // structure
-        self.parse_dot_or_call_expr_with_(e0, lo).map(|expr|
-            expr.map(|mut expr| {
-                attrs.extend::<Vec<_>>(expr.attrs.into());
-                expr.attrs = attrs;
-                match expr.kind {
-                    ExprKind::If(..) if !expr.attrs.is_empty() => {
-                        // Just point to the first attribute in there...
-                        let span = expr.attrs[0].span;
-                        self.span_err(span, "attributes are not yet allowed on `if` expressions");
-                    }
-                    _ => {}
-                }
-                expr
-            })
-        )
-    }
-
-    fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
-        let mut e = e0;
-        let mut hi;
-        loop {
-            // expr?
-            while self.eat(&token::Question) {
-                let hi = self.prev_span;
-                e = self.mk_expr(lo.to(hi), ExprKind::Try(e), ThinVec::new());
-            }
-
-            // expr.f
-            if self.eat(&token::Dot) {
-                match self.token.kind {
-                    token::Ident(..) => {
-                        e = self.parse_dot_suffix(e, lo)?;
-                    }
-                    token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) => {
-                        let span = self.token.span;
-                        self.bump();
-                        let field = ExprKind::Field(e, Ident::new(symbol, span));
-                        e = self.mk_expr(lo.to(span), field, ThinVec::new());
-
-                        self.expect_no_suffix(span, "a tuple index", suffix);
-                    }
-                    token::Literal(token::Lit { kind: token::Float, symbol, .. }) => {
-                      self.bump();
-                      let fstr = symbol.as_str();
-                      let msg = format!("unexpected token: `{}`", symbol);
-                      let mut err = self.diagnostic().struct_span_err(self.prev_span, &msg);
-                      err.span_label(self.prev_span, "unexpected token");
-                      if fstr.chars().all(|x| "0123456789.".contains(x)) {
-                          let float = match fstr.parse::<f64>().ok() {
-                              Some(f) => f,
-                              None => continue,
-                          };
-                          let sugg = pprust::to_string(|s| {
-                              s.popen();
-                              s.print_expr(&e);
-                              s.s.word( ".");
-                              s.print_usize(float.trunc() as usize);
-                              s.pclose();
-                              s.s.word(".");
-                              s.s.word(fstr.splitn(2, ".").last().unwrap().to_string())
-                          });
-                          err.span_suggestion(
-                              lo.to(self.prev_span),
-                              "try parenthesizing the first index",
-                              sugg,
-                              Applicability::MachineApplicable
-                          );
-                      }
-                      return Err(err);
-
-                    }
-                    _ => {
-                        // FIXME Could factor this out into non_fatal_unexpected or something.
-                        let actual = self.this_token_to_string();
-                        self.span_err(self.token.span, &format!("unexpected token: `{}`", actual));
-                    }
-                }
-                continue;
-            }
-            if self.expr_is_complete(&e) { break; }
-            match self.token.kind {
-                // expr(...)
-                token::OpenDelim(token::Paren) => {
-                    let seq = self.parse_paren_expr_seq().map(|es| {
-                        let nd = self.mk_call(e, es);
-                        let hi = self.prev_span;
-                        self.mk_expr(lo.to(hi), nd, ThinVec::new())
-                    });
-                    e = self.recover_seq_parse_error(token::Paren, lo, seq);
-                }
-
-                // expr[...]
-                // Could be either an index expression or a slicing expression.
-                token::OpenDelim(token::Bracket) => {
-                    self.bump();
-                    let ix = self.parse_expr()?;
-                    hi = self.token.span;
-                    self.expect(&token::CloseDelim(token::Bracket))?;
-                    let index = self.mk_index(e, ix);
-                    e = self.mk_expr(lo.to(hi), index, ThinVec::new())
-                }
-                _ => return Ok(e)
-            }
-        }
-        return Ok(e);
-    }
-
-    /// Assuming we have just parsed `.`, continue parsing into an expression.
-    fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
-        if self.token.span.rust_2018() && self.eat_keyword(kw::Await) {
-            return self.mk_await_expr(self_arg, lo);
-        }
-
-        let segment = self.parse_path_segment(PathStyle::Expr)?;
-        self.check_trailing_angle_brackets(&segment, token::OpenDelim(token::Paren));
-
-        Ok(match self.token.kind {
-            token::OpenDelim(token::Paren) => {
-                // Method call `expr.f()`
-                let mut args = self.parse_paren_expr_seq()?;
-                args.insert(0, self_arg);
-
-                let span = lo.to(self.prev_span);
-                self.mk_expr(span, ExprKind::MethodCall(segment, args), ThinVec::new())
-            }
-            _ => {
-                // Field access `expr.f`
-                if let Some(args) = segment.args {
-                    self.span_err(args.span(),
-                                  "field expressions may not have generic arguments");
-                }
-
-                let span = lo.to(self.prev_span);
-                self.mk_expr(span, ExprKind::Field(self_arg, segment.ident), ThinVec::new())
-            }
-        })
-    }
-
-    /// At the bottom (top?) of the precedence hierarchy,
-    /// Parses things like parenthesized exprs, macros, `return`, etc.
-    ///
-    /// N.B., this does not parse outer attributes, and is private because it only works
-    /// correctly if called from `parse_dot_or_call_expr()`.
-    fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> {
-        maybe_recover_from_interpolated_ty_qpath!(self, true);
-        maybe_whole_expr!(self);
-
-        // Outer attributes are already parsed and will be
-        // added to the return value after the fact.
-        //
-        // Therefore, prevent sub-parser from parsing
-        // attributes by giving them a empty "already-parsed" list.
-        let mut attrs = ThinVec::new();
-
-        let lo = self.token.span;
-        let mut hi = self.token.span;
-
-        let ex: ExprKind;
-
-        macro_rules! parse_lit {
-            () => {
-                match self.parse_lit() {
-                    Ok(literal) => {
-                        hi = self.prev_span;
-                        ex = ExprKind::Lit(literal);
-                    }
-                    Err(mut err) => {
-                        err.cancel();
-                        return Err(self.expected_expression_found());
-                    }
-                }
-            }
-        }
-
-        // Note: when adding new syntax here, don't forget to adjust `TokenKind::can_begin_expr()`.
-        match self.token.kind {
-            // This match arm is a special-case of the `_` match arm below and
-            // could be removed without changing functionality, but it's faster
-            // to have it here, especially for programs with large constants.
-            token::Literal(_) => {
-                parse_lit!()
-            }
-            token::OpenDelim(token::Paren) => {
-                self.bump();
-
-                attrs.extend(self.parse_inner_attributes()?);
-
-                // `(e)` is parenthesized `e`.
-                // `(e,)` is a tuple with only one field, `e`.
-                let mut es = vec![];
-                let mut trailing_comma = false;
-                let mut recovered = false;
-                while self.token != token::CloseDelim(token::Paren) {
-                    es.push(match self.parse_expr() {
-                        Ok(es) => es,
-                        Err(mut err) => {
-                            // Recover from parse error in tuple list.
-                            match self.token.kind {
-                                token::Ident(name, false)
-                                if name == kw::Underscore && self.look_ahead(1, |t| {
-                                    t == &token::Comma
-                                }) => {
-                                    // Special-case handling of `Foo<(_, _, _)>`
-                                    err.emit();
-                                    let sp = self.token.span;
-                                    self.bump();
-                                    self.mk_expr(sp, ExprKind::Err, ThinVec::new())
-                                }
-                                _ => return Ok(
-                                    self.recover_seq_parse_error(token::Paren, lo, Err(err)),
-                                ),
-                            }
-                        }
-                    });
-                    recovered = self.expect_one_of(
-                        &[],
-                        &[token::Comma, token::CloseDelim(token::Paren)],
-                    )?;
-                    if self.eat(&token::Comma) {
-                        trailing_comma = true;
-                    } else {
-                        trailing_comma = false;
-                        break;
-                    }
-                }
-                if !recovered {
-                    self.bump();
-                }
-
-                hi = self.prev_span;
-                ex = if es.len() == 1 && !trailing_comma {
-                    ExprKind::Paren(es.into_iter().nth(0).unwrap())
-                } else {
-                    ExprKind::Tup(es)
-                };
-            }
-            token::OpenDelim(token::Brace) => {
-                return self.parse_block_expr(None, lo, BlockCheckMode::Default, attrs);
-            }
-            token::BinOp(token::Or) | token::OrOr => {
-                return self.parse_closure_expr(attrs);
-            }
-            token::OpenDelim(token::Bracket) => {
-                self.bump();
-
-                attrs.extend(self.parse_inner_attributes()?);
-
-                if self.eat(&token::CloseDelim(token::Bracket)) {
-                    // Empty vector
-                    ex = ExprKind::Array(Vec::new());
-                } else {
-                    // Non-empty vector
-                    let first_expr = self.parse_expr()?;
-                    if self.eat(&token::Semi) {
-                        // Repeating array syntax: `[ 0; 512 ]`
-                        let count = AnonConst {
-                            id: DUMMY_NODE_ID,
-                            value: self.parse_expr()?,
-                        };
-                        self.expect(&token::CloseDelim(token::Bracket))?;
-                        ex = ExprKind::Repeat(first_expr, count);
-                    } else if self.eat(&token::Comma) {
-                        // Vector with two or more elements
-                        let remaining_exprs = self.parse_seq_to_end(
-                            &token::CloseDelim(token::Bracket),
-                            SeqSep::trailing_allowed(token::Comma),
-                            |p| Ok(p.parse_expr()?)
-                        )?;
-                        let mut exprs = vec![first_expr];
-                        exprs.extend(remaining_exprs);
-                        ex = ExprKind::Array(exprs);
-                    } else {
-                        // Vector with one element
-                        self.expect(&token::CloseDelim(token::Bracket))?;
-                        ex = ExprKind::Array(vec![first_expr]);
-                    }
-                }
-                hi = self.prev_span;
-            }
-            _ => {
-                if self.eat_lt() {
-                    let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
-                    hi = path.span;
-                    return Ok(self.mk_expr(lo.to(hi), ExprKind::Path(Some(qself), path), attrs));
-                }
-                if self.token.is_path_start() {
-                    let path = self.parse_path(PathStyle::Expr)?;
-
-                    // `!`, as an operator, is prefix, so we know this isn't that.
-                    if self.eat(&token::Not) {
-                        // MACRO INVOCATION expression
-                        let (delim, tts) = self.expect_delimited_token_tree()?;
-                        hi = self.prev_span;
-                        ex = ExprKind::Mac(Mac {
-                            path,
-                            tts,
-                            delim,
-                            span: lo.to(hi),
-                            prior_type_ascription: self.last_type_ascription,
-                        });
-                    } else if self.check(&token::OpenDelim(token::Brace)) {
-                        if let Some(expr) = self.maybe_parse_struct_expr(lo, &path, &attrs) {
-                            return expr;
-                        } else {
-                            hi = path.span;
-                            ex = ExprKind::Path(None, path);
-                        }
-                    } else {
-                        hi = path.span;
-                        ex = ExprKind::Path(None, path);
-                    }
-
-                    let expr = self.mk_expr(lo.to(hi), ex, attrs);
-                    return self.maybe_recover_from_bad_qpath(expr, true);
-                }
-                if self.check_keyword(kw::Move) || self.check_keyword(kw::Static) {
-                    return self.parse_closure_expr(attrs);
-                }
-                if self.eat_keyword(kw::If) {
-                    return self.parse_if_expr(attrs);
-                }
-                if self.eat_keyword(kw::For) {
-                    let lo = self.prev_span;
-                    return self.parse_for_expr(None, lo, attrs);
-                }
-                if self.eat_keyword(kw::While) {
-                    let lo = self.prev_span;
-                    return self.parse_while_expr(None, lo, attrs);
-                }
-                if let Some(label) = self.eat_label() {
-                    let lo = label.ident.span;
-                    self.expect(&token::Colon)?;
-                    if self.eat_keyword(kw::While) {
-                        return self.parse_while_expr(Some(label), lo, attrs)
-                    }
-                    if self.eat_keyword(kw::For) {
-                        return self.parse_for_expr(Some(label), lo, attrs)
-                    }
-                    if self.eat_keyword(kw::Loop) {
-                        return self.parse_loop_expr(Some(label), lo, attrs)
-                    }
-                    if self.token == token::OpenDelim(token::Brace) {
-                        return self.parse_block_expr(Some(label),
-                                                     lo,
-                                                     BlockCheckMode::Default,
-                                                     attrs);
-                    }
-                    let msg = "expected `while`, `for`, `loop` or `{` after a label";
-                    let mut err = self.fatal(msg);
-                    err.span_label(self.token.span, msg);
-                    return Err(err);
-                }
-                if self.eat_keyword(kw::Loop) {
-                    let lo = self.prev_span;
-                    return self.parse_loop_expr(None, lo, attrs);
-                }
-                if self.eat_keyword(kw::Continue) {
-                    let label = self.eat_label();
-                    let ex = ExprKind::Continue(label);
-                    let hi = self.prev_span;
-                    return Ok(self.mk_expr(lo.to(hi), ex, attrs));
-                }
-                if self.eat_keyword(kw::Match) {
-                    let match_sp = self.prev_span;
-                    return self.parse_match_expr(attrs).map_err(|mut err| {
-                        err.span_label(match_sp, "while parsing this match expression");
-                        err
-                    });
-                }
-                if self.eat_keyword(kw::Unsafe) {
-                    return self.parse_block_expr(
-                        None,
-                        lo,
-                        BlockCheckMode::Unsafe(ast::UserProvided),
-                        attrs);
-                }
-                if self.is_do_catch_block() {
-                    let mut db = self.fatal("found removed `do catch` syntax");
-                    db.help("following RFC #2388, the new non-placeholder syntax is `try`");
-                    return Err(db);
-                }
-                if self.is_try_block() {
-                    let lo = self.token.span;
-                    assert!(self.eat_keyword(kw::Try));
-                    return self.parse_try_block(lo, attrs);
-                }
-
-                // `Span::rust_2018()` is somewhat expensive; don't get it repeatedly.
-                let is_span_rust_2018 = self.token.span.rust_2018();
-                if is_span_rust_2018 && self.check_keyword(kw::Async) {
-                    return if self.is_async_block() { // Check for `async {` and `async move {`.
-                        self.parse_async_block(attrs)
-                    } else {
-                        self.parse_closure_expr(attrs)
-                    };
-                }
-                if self.eat_keyword(kw::Return) {
-                    if self.token.can_begin_expr() {
-                        let e = self.parse_expr()?;
-                        hi = e.span;
-                        ex = ExprKind::Ret(Some(e));
-                    } else {
-                        ex = ExprKind::Ret(None);
-                    }
-                } else if self.eat_keyword(kw::Break) {
-                    let label = self.eat_label();
-                    let e = if self.token.can_begin_expr()
-                               && !(self.token == token::OpenDelim(token::Brace)
-                                    && self.restrictions.contains(
-                                           Restrictions::NO_STRUCT_LITERAL)) {
-                        Some(self.parse_expr()?)
-                    } else {
-                        None
-                    };
-                    ex = ExprKind::Break(label, e);
-                    hi = self.prev_span;
-                } else if self.eat_keyword(kw::Yield) {
-                    if self.token.can_begin_expr() {
-                        let e = self.parse_expr()?;
-                        hi = e.span;
-                        ex = ExprKind::Yield(Some(e));
-                    } else {
-                        ex = ExprKind::Yield(None);
-                    }
-
-                    let span = lo.to(hi);
-                    self.sess.gated_spans.gate(sym::generators, span);
-                } else if self.eat_keyword(kw::Let) {
-                    return self.parse_let_expr(attrs);
-                } else if is_span_rust_2018 && self.eat_keyword(kw::Await) {
-                    let (await_hi, e_kind) = self.parse_incorrect_await_syntax(lo, self.prev_span)?;
-                    hi = await_hi;
-                    ex = e_kind;
-                } else {
-                    if !self.unclosed_delims.is_empty() && self.check(&token::Semi) {
-                        // Don't complain about bare semicolons after unclosed braces
-                        // recovery in order to keep the error count down. Fixing the
-                        // delimiters will possibly also fix the bare semicolon found in
-                        // expression context. For example, silence the following error:
-                        //
-                        //     error: expected expression, found `;`
-                        //      --> file.rs:2:13
-                        //       |
-                        //     2 |     foo(bar(;
-                        //       |             ^ expected expression
-                        self.bump();
-                        return Ok(self.mk_expr(self.token.span, ExprKind::Err, ThinVec::new()));
-                    }
-                    parse_lit!()
-                }
-            }
-        }
-
-        let expr = self.mk_expr(lo.to(hi), ex, attrs);
-        self.maybe_recover_from_bad_qpath(expr, true)
-    }
-
-    /// Matches `lit = true | false | token_lit`.
-    pub(super) fn parse_lit(&mut self) -> PResult<'a, Lit> {
-        let mut recovered = None;
-        if self.token == token::Dot {
-            // Attempt to recover `.4` as `0.4`.
-            recovered = self.look_ahead(1, |next_token| {
-                if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix })
-                        = next_token.kind {
-                    if self.token.span.hi() == next_token.span.lo() {
-                        let s = String::from("0.") + &symbol.as_str();
-                        let kind = TokenKind::lit(token::Float, Symbol::intern(&s), suffix);
-                        return Some(Token::new(kind, self.token.span.to(next_token.span)));
-                    }
-                }
-                None
-            });
-            if let Some(token) = &recovered {
-                self.bump();
-                self.struct_span_err(token.span, "float literals must have an integer part")
-                    .span_suggestion(
-                        token.span,
-                        "must have an integer part",
-                        pprust::token_to_string(token),
-                        Applicability::MachineApplicable,
-                    )
-                    .emit();
-            }
-        }
-
-        let token = recovered.as_ref().unwrap_or(&self.token);
-        match Lit::from_token(token) {
-            Ok(lit) => {
-                self.bump();
-                Ok(lit)
-            }
-            Err(LitError::NotLiteral) => {
-                let msg = format!("unexpected token: {}", self.this_token_descr());
-                Err(self.span_fatal(token.span, &msg))
-            }
-            Err(err) => {
-                let span = token.span;
-                let lit = match token.kind {
-                    token::Literal(lit) => lit,
-                    _ => unreachable!(),
-                };
-                self.bump();
-                self.error_literal_from_token(err, lit, span);
-                // Pack possible quotes and prefixes from the original literal into
-                // the error literal's symbol so they can be pretty-printed faithfully.
-                let suffixless_lit = token::Lit::new(lit.kind, lit.symbol, None);
-                let symbol = Symbol::intern(&suffixless_lit.to_string());
-                let lit = token::Lit::new(token::Err, symbol, lit.suffix);
-                Lit::from_lit_token(lit, span).map_err(|_| unreachable!())
-            }
-        }
-    }
-
-    fn error_literal_from_token(&self, err: LitError, lit: token::Lit, span: Span) {
-        // Checks if `s` looks like i32 or u1234 etc.
-        fn looks_like_width_suffix(first_chars: &[char], s: &str) -> bool {
-            s.len() > 1
-            && s.starts_with(first_chars)
-            && s[1..].chars().all(|c| c.is_ascii_digit())
-        }
-
-        let token::Lit { kind, suffix, .. } = lit;
-        match err {
-            // `NotLiteral` is not an error by itself, so we don't report
-            // it and give the parser opportunity to try something else.
-            LitError::NotLiteral => {}
-            // `LexerError` *is* an error, but it was already reported
-            // by lexer, so here we don't report it the second time.
-            LitError::LexerError => {}
-            LitError::InvalidSuffix => {
-                self.expect_no_suffix(
-                    span,
-                    &format!("{} {} literal", kind.article(), kind.descr()),
-                    suffix,
-                );
-            }
-            LitError::InvalidIntSuffix => {
-                let suf = suffix.expect("suffix error with no suffix").as_str();
-                if looks_like_width_suffix(&['i', 'u'], &suf) {
-                    // If it looks like a width, try to be helpful.
-                    let msg = format!("invalid width `{}` for integer literal", &suf[1..]);
-                    self.struct_span_err(span, &msg)
-                        .help("valid widths are 8, 16, 32, 64 and 128")
-                        .emit();
-                } else {
-                    let msg = format!("invalid suffix `{}` for integer literal", suf);
-                    self.struct_span_err(span, &msg)
-                        .span_label(span, format!("invalid suffix `{}`", suf))
-                        .help("the suffix must be one of the integral types (`u32`, `isize`, etc)")
-                        .emit();
-                }
-            }
-            LitError::InvalidFloatSuffix => {
-                let suf = suffix.expect("suffix error with no suffix").as_str();
-                if looks_like_width_suffix(&['f'], &suf) {
-                    // If it looks like a width, try to be helpful.
-                    let msg = format!("invalid width `{}` for float literal", &suf[1..]);
-                    self.struct_span_err(span, &msg)
-                        .help("valid widths are 32 and 64")
-                        .emit();
-                } else {
-                    let msg = format!("invalid suffix `{}` for float literal", suf);
-                    self.struct_span_err(span, &msg)
-                        .span_label(span, format!("invalid suffix `{}`", suf))
-                        .help("valid suffixes are `f32` and `f64`")
-                        .emit();
-                }
-            }
-            LitError::NonDecimalFloat(base) => {
-                let descr = match base {
-                    16 => "hexadecimal",
-                    8 => "octal",
-                    2 => "binary",
-                    _ => unreachable!(),
-                };
-                self.struct_span_err(span, &format!("{} float literal is not supported", descr))
-                    .span_label(span, "not supported")
-                    .emit();
-            }
-            LitError::IntTooLarge => {
-                self.struct_span_err(span, "integer literal is too large")
-                    .emit();
-            }
-        }
-    }
-
-    pub(super) fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<Symbol>) {
-        if let Some(suf) = suffix {
-            let mut err = if kind == "a tuple index"
-                && [sym::i32, sym::u32, sym::isize, sym::usize].contains(&suf)
-            {
-                // #59553: warn instead of reject out of hand to allow the fix to percolate
-                // through the ecosystem when people fix their macros
-                let mut err = self.sess.span_diagnostic.struct_span_warn(
-                    sp,
-                    &format!("suffixes on {} are invalid", kind),
-                );
-                err.note(&format!(
-                    "`{}` is *temporarily* accepted on tuple index fields as it was \
-                        incorrectly accepted on stable for a few releases",
-                    suf,
-                ));
-                err.help(
-                    "on proc macros, you'll want to use `syn::Index::from` or \
-                        `proc_macro::Literal::*_unsuffixed` for code that will desugar \
-                        to tuple field access",
-                );
-                err.note(
-                    "for more context, see https://github.com/rust-lang/rust/issues/60210",
-                );
-                err
-            } else {
-                self.struct_span_err(sp, &format!("suffixes on {} are invalid", kind))
-            };
-            err.span_label(sp, format!("invalid suffix `{}`", suf));
-            err.emit();
-        }
-    }
-
-    /// Matches `'-' lit | lit` (cf. `ast_validation::AstValidator::check_expr_within_pat`).
-    pub fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
-        maybe_whole_expr!(self);
-
-        let minus_lo = self.token.span;
-        let minus_present = self.eat(&token::BinOp(token::Minus));
-        let lo = self.token.span;
-        let literal = self.parse_lit()?;
-        let hi = self.prev_span;
-        let expr = self.mk_expr(lo.to(hi), ExprKind::Lit(literal), ThinVec::new());
-
-        if minus_present {
-            let minus_hi = self.prev_span;
-            let unary = self.mk_unary(UnOp::Neg, expr);
-            Ok(self.mk_expr(minus_lo.to(minus_hi), unary, ThinVec::new()))
-        } else {
-            Ok(expr)
-        }
-    }
-
-    /// Parses a block or unsafe block.
-    pub(super) fn parse_block_expr(
-        &mut self,
-        opt_label: Option<Label>,
-        lo: Span,
-        blk_mode: BlockCheckMode,
-        outer_attrs: ThinVec<Attribute>,
-    ) -> PResult<'a, P<Expr>> {
-        if let Some(label) = opt_label {
-            self.sess.gated_spans.gate(sym::label_break_value, label.ident.span);
-        }
-
-        self.expect(&token::OpenDelim(token::Brace))?;
-
-        let mut attrs = outer_attrs;
-        attrs.extend(self.parse_inner_attributes()?);
-
-        let blk = self.parse_block_tail(lo, blk_mode)?;
-        Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs))
-    }
-
-    /// Parses a closure expression (e.g., `move |args| expr`).
-    fn parse_closure_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
-        let lo = self.token.span;
-
-        let movability = if self.eat_keyword(kw::Static) {
-            Movability::Static
-        } else {
-            Movability::Movable
-        };
-
-        let asyncness = if self.token.span.rust_2018() {
-            self.parse_asyncness()
-        } else {
-            IsAsync::NotAsync
-        };
-        if asyncness.is_async() {
-            // Feature-gate `async ||` closures.
-            self.sess.gated_spans.gate(sym::async_closure, self.prev_span);
-        }
-
-        let capture_clause = self.parse_capture_clause();
-        let decl = self.parse_fn_block_decl()?;
-        let decl_hi = self.prev_span;
-        let body = match decl.output {
-            FunctionRetTy::Default(_) => {
-                let restrictions = self.restrictions - Restrictions::STMT_EXPR;
-                self.parse_expr_res(restrictions, None)?
-            },
-            _ => {
-                // If an explicit return type is given, require a block to appear (RFC 968).
-                let body_lo = self.token.span;
-                self.parse_block_expr(None, body_lo, BlockCheckMode::Default, ThinVec::new())?
-            }
-        };
-
-        Ok(self.mk_expr(
-            lo.to(body.span),
-            ExprKind::Closure(capture_clause, asyncness, movability, decl, body, lo.to(decl_hi)),
-            attrs))
-    }
-
-    /// Parses an optional `move` prefix to a closure lke construct.
-    fn parse_capture_clause(&mut self) -> CaptureBy {
-        if self.eat_keyword(kw::Move) {
-            CaptureBy::Value
-        } else {
-            CaptureBy::Ref
-        }
-    }
-
-    /// Parses the `|arg, arg|` header of a closure.
-    fn parse_fn_block_decl(&mut self) -> PResult<'a, P<FnDecl>> {
-        let inputs_captures = {
-            if self.eat(&token::OrOr) {
-                Vec::new()
-            } else {
-                self.expect(&token::BinOp(token::Or))?;
-                let args = self.parse_seq_to_before_tokens(
-                    &[&token::BinOp(token::Or), &token::OrOr],
-                    SeqSep::trailing_allowed(token::Comma),
-                    TokenExpectType::NoExpect,
-                    |p| p.parse_fn_block_param()
-                )?.0;
-                self.expect_or()?;
-                args
-            }
-        };
-        let output = self.parse_ret_ty(true)?;
-
-        Ok(P(FnDecl {
-            inputs: inputs_captures,
-            output,
-        }))
-    }
-
-    /// Parses a parameter in a closure header (e.g., `|arg, arg|`).
-    fn parse_fn_block_param(&mut self) -> PResult<'a, Param> {
-        let lo = self.token.span;
-        let attrs = self.parse_outer_attributes()?;
-        let pat = self.parse_pat(PARAM_EXPECTED)?;
-        let t = if self.eat(&token::Colon) {
-            self.parse_ty()?
-        } else {
-            P(Ty {
-                id: DUMMY_NODE_ID,
-                kind: TyKind::Infer,
-                span: self.prev_span,
-            })
-        };
-        let span = lo.to(self.token.span);
-        Ok(Param {
-            attrs: attrs.into(),
-            ty: t,
-            pat,
-            span,
-            id: DUMMY_NODE_ID,
-            is_placeholder: false,
-        })
-    }
-
-    /// Parses an `if` expression (`if` token already eaten).
-    fn parse_if_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
-        let lo = self.prev_span;
-        let cond = self.parse_cond_expr()?;
-
-        // Verify that the parsed `if` condition makes sense as a condition. If it is a block, then
-        // verify that the last statement is either an implicit return (no `;`) or an explicit
-        // return. This won't catch blocks with an explicit `return`, but that would be caught by
-        // the dead code lint.
-        if self.eat_keyword(kw::Else) || !cond.returns() {
-            let sp = self.sess.source_map().next_point(lo);
-            let mut err = self.diagnostic()
-                .struct_span_err(sp, "missing condition for `if` expression");
-            err.span_label(sp, "expected if condition here");
-            return Err(err)
-        }
-        let not_block = self.token != token::OpenDelim(token::Brace);
-        let thn = self.parse_block().map_err(|mut err| {
-            if not_block {
-                err.span_label(lo, "this `if` statement has a condition, but no block");
-            }
-            err
-        })?;
-        let mut els: Option<P<Expr>> = None;
-        let mut hi = thn.span;
-        if self.eat_keyword(kw::Else) {
-            let elexpr = self.parse_else_expr()?;
-            hi = elexpr.span;
-            els = Some(elexpr);
-        }
-        Ok(self.mk_expr(lo.to(hi), ExprKind::If(cond, thn, els), attrs))
-    }
-
-    /// Parses the condition of a `if` or `while` expression.
-    fn parse_cond_expr(&mut self) -> PResult<'a, P<Expr>> {
-        let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
-
-        if let ExprKind::Let(..) = cond.kind {
-            // Remove the last feature gating of a `let` expression since it's stable.
-            self.sess.gated_spans.ungate_last(sym::let_chains, cond.span);
-        }
-
-        Ok(cond)
-    }
-
-    /// Parses a `let $pat = $expr` pseudo-expression.
-    /// The `let` token has already been eaten.
-    fn parse_let_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
-        let lo = self.prev_span;
-        let pat = self.parse_top_pat(GateOr::No)?;
-        self.expect(&token::Eq)?;
-        let expr = self.with_res(
-            Restrictions::NO_STRUCT_LITERAL,
-            |this| this.parse_assoc_expr_with(1 + prec_let_scrutinee_needs_par(), None.into())
-        )?;
-        let span = lo.to(expr.span);
-        self.sess.gated_spans.gate(sym::let_chains, span);
-        Ok(self.mk_expr(span, ExprKind::Let(pat, expr), attrs))
-    }
-
-    /// Parses an `else { ... }` expression (`else` token already eaten).
-    fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
-        if self.eat_keyword(kw::If) {
-            return self.parse_if_expr(ThinVec::new());
-        } else {
-            let blk = self.parse_block()?;
-            return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, None), ThinVec::new()));
-        }
-    }
-
-    /// Parses a `for ... in` expression (`for` token already eaten).
-    fn parse_for_expr(
-        &mut self,
-        opt_label: Option<Label>,
-        span_lo: Span,
-        mut attrs: ThinVec<Attribute>
-    ) -> PResult<'a, P<Expr>> {
-        // Parse: `for <src_pat> in <src_expr> <src_loop_block>`
-
-        // Record whether we are about to parse `for (`.
-        // This is used below for recovery in case of `for ( $stuff ) $block`
-        // in which case we will suggest `for $stuff $block`.
-        let begin_paren = match self.token.kind {
-            token::OpenDelim(token::Paren) => Some(self.token.span),
-            _ => None,
-        };
-
-        let pat = self.parse_top_pat(GateOr::Yes)?;
-        if !self.eat_keyword(kw::In) {
-            let in_span = self.prev_span.between(self.token.span);
-            self.struct_span_err(in_span, "missing `in` in `for` loop")
-                .span_suggestion_short(
-                    in_span,
-                    "try adding `in` here", " in ".into(),
-                    // has been misleading, at least in the past (closed Issue #48492)
-                    Applicability::MaybeIncorrect
-                )
-                .emit();
-        }
-        let in_span = self.prev_span;
-        self.check_for_for_in_in_typo(in_span);
-        let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
-
-        let pat = self.recover_parens_around_for_head(pat, &expr, begin_paren);
-
-        let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?;
-        attrs.extend(iattrs);
-
-        let hi = self.prev_span;
-        Ok(self.mk_expr(span_lo.to(hi), ExprKind::ForLoop(pat, expr, loop_block, opt_label), attrs))
-    }
-
-    /// Parses a `while` or `while let` expression (`while` token already eaten).
-    fn parse_while_expr(
-        &mut self,
-        opt_label: Option<Label>,
-        span_lo: Span,
-        mut attrs: ThinVec<Attribute>
-    ) -> PResult<'a, P<Expr>> {
-        let cond = self.parse_cond_expr()?;
-        let (iattrs, body) = self.parse_inner_attrs_and_block()?;
-        attrs.extend(iattrs);
-        let span = span_lo.to(body.span);
-        Ok(self.mk_expr(span, ExprKind::While(cond, body, opt_label), attrs))
-    }
-
-    /// Parses `loop { ... }` (`loop` token already eaten).
-    fn parse_loop_expr(
-        &mut self,
-        opt_label: Option<Label>,
-        span_lo: Span,
-        mut attrs: ThinVec<Attribute>
-    ) -> PResult<'a, P<Expr>> {
-        let (iattrs, body) = self.parse_inner_attrs_and_block()?;
-        attrs.extend(iattrs);
-        let span = span_lo.to(body.span);
-        Ok(self.mk_expr(span, ExprKind::Loop(body, opt_label), attrs))
-    }
-
-    fn eat_label(&mut self) -> Option<Label> {
-        if let Some(ident) = self.token.lifetime() {
-            let span = self.token.span;
-            self.bump();
-            Some(Label { ident: Ident::new(ident.name, span) })
-        } else {
-            None
-        }
-    }
-
-    /// Parses a `match ... { ... }` expression (`match` token already eaten).
-    fn parse_match_expr(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
-        let match_span = self.prev_span;
-        let lo = self.prev_span;
-        let discriminant = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
-        if let Err(mut e) = self.expect(&token::OpenDelim(token::Brace)) {
-            if self.token == token::Semi {
-                e.span_suggestion_short(
-                    match_span,
-                    "try removing this `match`",
-                    String::new(),
-                    Applicability::MaybeIncorrect // speculative
-                );
-            }
-            return Err(e)
-        }
-        attrs.extend(self.parse_inner_attributes()?);
-
-        let mut arms: Vec<Arm> = Vec::new();
-        while self.token != token::CloseDelim(token::Brace) {
-            match self.parse_arm() {
-                Ok(arm) => arms.push(arm),
-                Err(mut e) => {
-                    // Recover by skipping to the end of the block.
-                    e.emit();
-                    self.recover_stmt();
-                    let span = lo.to(self.token.span);
-                    if self.token == token::CloseDelim(token::Brace) {
-                        self.bump();
-                    }
-                    return Ok(self.mk_expr(span, ExprKind::Match(discriminant, arms), attrs));
-                }
-            }
-        }
-        let hi = self.token.span;
-        self.bump();
-        return Ok(self.mk_expr(lo.to(hi), ExprKind::Match(discriminant, arms), attrs));
-    }
-
-    pub(super) fn parse_arm(&mut self) -> PResult<'a, Arm> {
-        let attrs = self.parse_outer_attributes()?;
-        let lo = self.token.span;
-        let pat = self.parse_top_pat(GateOr::No)?;
-        let guard = if self.eat_keyword(kw::If) {
-            Some(self.parse_expr()?)
-        } else {
-            None
-        };
-        let arrow_span = self.token.span;
-        self.expect(&token::FatArrow)?;
-        let arm_start_span = self.token.span;
-
-        let expr = self.parse_expr_res(Restrictions::STMT_EXPR, None)
-            .map_err(|mut err| {
-                err.span_label(arrow_span, "while parsing the `match` arm starting here");
-                err
-            })?;
-
-        let require_comma = classify::expr_requires_semi_to_be_stmt(&expr)
-            && self.token != token::CloseDelim(token::Brace);
-
-        let hi = self.token.span;
-
-        if require_comma {
-            let cm = self.sess.source_map();
-            self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Brace)])
-                .map_err(|mut err| {
-                    match (cm.span_to_lines(expr.span), cm.span_to_lines(arm_start_span)) {
-                        (Ok(ref expr_lines), Ok(ref arm_start_lines))
-                        if arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col
-                            && expr_lines.lines.len() == 2
-                            && self.token == token::FatArrow => {
-                            // We check whether there's any trailing code in the parse span,
-                            // if there isn't, we very likely have the following:
-                            //
-                            // X |     &Y => "y"
-                            //   |        --    - missing comma
-                            //   |        |
-                            //   |        arrow_span
-                            // X |     &X => "x"
-                            //   |      - ^^ self.token.span
-                            //   |      |
-                            //   |      parsed until here as `"y" & X`
-                            err.span_suggestion_short(
-                                cm.next_point(arm_start_span),
-                                "missing a comma here to end this `match` arm",
-                                ",".to_owned(),
-                                Applicability::MachineApplicable
-                            );
-                        }
-                        _ => {
-                            err.span_label(arrow_span,
-                                           "while parsing the `match` arm starting here");
-                        }
-                    }
-                    err
-                })?;
-        } else {
-            self.eat(&token::Comma);
-        }
-
-        Ok(ast::Arm {
-            attrs,
-            pat,
-            guard,
-            body: expr,
-            span: lo.to(hi),
-            id: DUMMY_NODE_ID,
-            is_placeholder: false,
-        })
-    }
-
-    /// Parses a `try {...}` expression (`try` token already eaten).
-    fn parse_try_block(
-        &mut self,
-        span_lo: Span,
-        mut attrs: ThinVec<Attribute>
-    ) -> PResult<'a, P<Expr>> {
-        let (iattrs, body) = self.parse_inner_attrs_and_block()?;
-        attrs.extend(iattrs);
-        if self.eat_keyword(kw::Catch) {
-            let mut error = self.struct_span_err(self.prev_span,
-                                                 "keyword `catch` cannot follow a `try` block");
-            error.help("try using `match` on the result of the `try` block instead");
-            error.emit();
-            Err(error)
-        } else {
-            let span = span_lo.to(body.span);
-            self.sess.gated_spans.gate(sym::try_blocks, span);
-            Ok(self.mk_expr(span, ExprKind::TryBlock(body), attrs))
-        }
-    }
-
-    fn is_do_catch_block(&self) -> bool {
-        self.token.is_keyword(kw::Do) &&
-        self.is_keyword_ahead(1, &[kw::Catch]) &&
-        self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) &&
-        !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
-    }
-
-    fn is_try_block(&self) -> bool {
-        self.token.is_keyword(kw::Try) &&
-        self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) &&
-        self.token.span.rust_2018() &&
-        // Prevent `while try {} {}`, `if try {} {} else {}`, etc.
-        !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
-    }
-
-    /// Parses an `async move? {...}` expression.
-    fn parse_async_block(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
-        let span_lo = self.token.span;
-        self.expect_keyword(kw::Async)?;
-        let capture_clause = self.parse_capture_clause();
-        let (iattrs, body) = self.parse_inner_attrs_and_block()?;
-        attrs.extend(iattrs);
-        Ok(self.mk_expr(
-            span_lo.to(body.span),
-            ExprKind::Async(capture_clause, DUMMY_NODE_ID, body), attrs))
-    }
-
-    fn is_async_block(&self) -> bool {
-        self.token.is_keyword(kw::Async) &&
-        (
-            ( // `async move {`
-                self.is_keyword_ahead(1, &[kw::Move]) &&
-                self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))
-            ) || ( // `async {`
-                self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace))
-            )
-        )
-    }
-
-    fn maybe_parse_struct_expr(
-        &mut self,
-        lo: Span,
-        path: &ast::Path,
-        attrs: &ThinVec<Attribute>,
-    ) -> Option<PResult<'a, P<Expr>>> {
-        let struct_allowed = !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
-        let certainly_not_a_block = || self.look_ahead(1, |t| t.is_ident()) && (
-            // `{ ident, ` cannot start a block.
-            self.look_ahead(2, |t| t == &token::Comma) ||
-            self.look_ahead(2, |t| t == &token::Colon) && (
-                // `{ ident: token, ` cannot start a block.
-                self.look_ahead(4, |t| t == &token::Comma) ||
-                // `{ ident: ` cannot start a block unless it's a type ascription `ident: Type`.
-                self.look_ahead(3, |t| !t.can_begin_type())
-            )
-        );
-
-        if struct_allowed || certainly_not_a_block() {
-            // This is a struct literal, but we don't can't accept them here.
-            let expr = self.parse_struct_expr(lo, path.clone(), attrs.clone());
-            if let (Ok(expr), false) = (&expr, struct_allowed) {
-                self.struct_span_err(
-                    expr.span,
-                    "struct literals are not allowed here",
-                )
-                .multipart_suggestion(
-                    "surround the struct literal with parentheses",
-                    vec![
-                        (lo.shrink_to_lo(), "(".to_string()),
-                        (expr.span.shrink_to_hi(), ")".to_string()),
-                    ],
-                    Applicability::MachineApplicable,
-                )
-                .emit();
-            }
-            return Some(expr);
-        }
-        None
-    }
-
-    pub(super) fn parse_struct_expr(
-        &mut self,
-        lo: Span,
-        pth: ast::Path,
-        mut attrs: ThinVec<Attribute>
-    ) -> PResult<'a, P<Expr>> {
-        let struct_sp = lo.to(self.prev_span);
-        self.bump();
-        let mut fields = Vec::new();
-        let mut base = None;
-
-        attrs.extend(self.parse_inner_attributes()?);
-
-        while self.token != token::CloseDelim(token::Brace) {
-            if self.eat(&token::DotDot) {
-                let exp_span = self.prev_span;
-                match self.parse_expr() {
-                    Ok(e) => {
-                        base = Some(e);
-                    }
-                    Err(mut e) => {
-                        e.emit();
-                        self.recover_stmt();
-                    }
-                }
-                if self.token == token::Comma {
-                    self.struct_span_err(
-                        exp_span.to(self.prev_span),
-                        "cannot use a comma after the base struct",
-                    )
-                    .span_suggestion_short(
-                        self.token.span,
-                        "remove this comma",
-                        String::new(),
-                        Applicability::MachineApplicable
-                    )
-                    .note("the base struct must always be the last field")
-                    .emit();
-                    self.recover_stmt();
-                }
-                break;
-            }
-
-            let mut recovery_field = None;
-            if let token::Ident(name, _) = self.token.kind {
-                if !self.token.is_reserved_ident() && self.look_ahead(1, |t| *t == token::Colon) {
-                    // Use in case of error after field-looking code: `S { foo: () with a }`.
-                    recovery_field = Some(ast::Field {
-                        ident: Ident::new(name, self.token.span),
-                        span: self.token.span,
-                        expr: self.mk_expr(self.token.span, ExprKind::Err, ThinVec::new()),
-                        is_shorthand: false,
-                        attrs: ThinVec::new(),
-                        id: DUMMY_NODE_ID,
-                        is_placeholder: false,
-                    });
-                }
-            }
-            let mut parsed_field = None;
-            match self.parse_field() {
-                Ok(f) => parsed_field = Some(f),
-                Err(mut e) => {
-                    e.span_label(struct_sp, "while parsing this struct");
-                    e.emit();
-
-                    // If the next token is a comma, then try to parse
-                    // what comes next as additional fields, rather than
-                    // bailing out until next `}`.
-                    if self.token != token::Comma {
-                        self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore);
-                        if self.token != token::Comma {
-                            break;
-                        }
-                    }
-                }
-            }
-
-            match self.expect_one_of(&[token::Comma],
-                                     &[token::CloseDelim(token::Brace)]) {
-                Ok(_) => if let Some(f) = parsed_field.or(recovery_field) {
-                    // Only include the field if there's no parse error for the field name.
-                    fields.push(f);
-                }
-                Err(mut e) => {
-                    if let Some(f) = recovery_field {
-                        fields.push(f);
-                    }
-                    e.span_label(struct_sp, "while parsing this struct");
-                    e.emit();
-                    self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore);
-                    self.eat(&token::Comma);
-                }
-            }
-        }
-
-        let span = lo.to(self.token.span);
-        self.expect(&token::CloseDelim(token::Brace))?;
-        return Ok(self.mk_expr(span, ExprKind::Struct(pth, fields, base), attrs));
-    }
-
-    /// Parses `ident (COLON expr)?`.
-    fn parse_field(&mut self) -> PResult<'a, Field> {
-        let attrs = self.parse_outer_attributes()?;
-        let lo = self.token.span;
-
-        // Check if a colon exists one ahead. This means we're parsing a fieldname.
-        let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| {
-            t == &token::Colon || t == &token::Eq
-        }) {
-            let fieldname = self.parse_field_name()?;
-
-            // Check for an equals token. This means the source incorrectly attempts to
-            // initialize a field with an eq rather than a colon.
-            if self.token == token::Eq {
-                self.diagnostic()
-                    .struct_span_err(self.token.span, "expected `:`, found `=`")
-                    .span_suggestion(
-                        fieldname.span.shrink_to_hi().to(self.token.span),
-                        "replace equals symbol with a colon",
-                        ":".to_string(),
-                        Applicability::MachineApplicable,
-                    )
-                    .emit();
-            }
-            self.bump(); // `:`
-            (fieldname, self.parse_expr()?, false)
-        } else {
-            let fieldname = self.parse_ident_common(false)?;
-
-            // Mimic `x: x` for the `x` field shorthand.
-            let path = ast::Path::from_ident(fieldname);
-            let expr = self.mk_expr(fieldname.span, ExprKind::Path(None, path), ThinVec::new());
-            (fieldname, expr, true)
-        };
-        Ok(ast::Field {
-            ident: fieldname,
-            span: lo.to(expr.span),
-            expr,
-            is_shorthand,
-            attrs: attrs.into(),
-            id: DUMMY_NODE_ID,
-            is_placeholder: false,
-        })
-    }
-
-    fn err_dotdotdot_syntax(&self, span: Span) {
-        self.struct_span_err(span, "unexpected token: `...`")
-            .span_suggestion(
-                span,
-                "use `..` for an exclusive range", "..".to_owned(),
-                Applicability::MaybeIncorrect
-            )
-            .span_suggestion(
-                span,
-                "or `..=` for an inclusive range", "..=".to_owned(),
-                Applicability::MaybeIncorrect
-            )
-            .emit();
-    }
-
-    fn err_larrow_operator(&self, span: Span) {
-        self.struct_span_err(
-            span,
-            "unexpected token: `<-`"
-        ).span_suggestion(
-            span,
-            "if you meant to write a comparison against a negative value, add a \
-             space in between `<` and `-`",
-            "< -".to_string(),
-            Applicability::MaybeIncorrect
-        ).emit();
-    }
-
-    fn mk_assign_op(&self, binop: BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ExprKind {
-        ExprKind::AssignOp(binop, lhs, rhs)
-    }
-
-    fn mk_range(
-        &self,
-        start: Option<P<Expr>>,
-        end: Option<P<Expr>>,
-        limits: RangeLimits
-    ) -> PResult<'a, ExprKind> {
-        if end.is_none() && limits == RangeLimits::Closed {
-            Err(self.span_fatal_err(self.token.span, Error::InclusiveRangeWithNoEnd))
-        } else {
-            Ok(ExprKind::Range(start, end, limits))
-        }
-    }
-
-    fn mk_unary(&self, unop: UnOp, expr: P<Expr>) -> ExprKind {
-        ExprKind::Unary(unop, expr)
-    }
-
-    fn mk_binary(&self, binop: BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ExprKind {
-        ExprKind::Binary(binop, lhs, rhs)
-    }
-
-    fn mk_index(&self, expr: P<Expr>, idx: P<Expr>) -> ExprKind {
-        ExprKind::Index(expr, idx)
-    }
-
-    fn mk_call(&self, f: P<Expr>, args: Vec<P<Expr>>) -> ExprKind {
-        ExprKind::Call(f, args)
-    }
-
-    fn mk_await_expr(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
-        let span = lo.to(self.prev_span);
-        let await_expr = self.mk_expr(span, ExprKind::Await(self_arg), ThinVec::new());
-        self.recover_from_await_method_call();
-        Ok(await_expr)
-    }
-
-    crate fn mk_expr(&self, span: Span, kind: ExprKind, attrs: ThinVec<Attribute>) -> P<Expr> {
-        P(Expr { kind, span, attrs, id: DUMMY_NODE_ID })
-    }
-
-    pub(super) fn mk_expr_err(&self, span: Span) -> P<Expr> {
-        self.mk_expr(span, ExprKind::Err, ThinVec::new())
-    }
-}
diff --git a/src/libsyntax/parse/parser/generics.rs b/src/libsyntax/parse/parser/generics.rs
deleted file mode 100644
index ae9ecd8fe39..00000000000
--- a/src/libsyntax/parse/parser/generics.rs
+++ /dev/null
@@ -1,309 +0,0 @@
-use super::Parser;
-
-use crate::ast::{self, WhereClause, GenericParam, GenericParamKind, GenericBounds, Attribute};
-use crate::token;
-use crate::source_map::DUMMY_SP;
-
-use syntax_pos::symbol::{kw, sym};
-
-use errors::PResult;
-
-impl<'a> Parser<'a> {
-    /// Parses bounds of a lifetime parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`.
-    ///
-    /// ```
-    /// BOUND = LT_BOUND (e.g., `'a`)
-    /// ```
-    fn parse_lt_param_bounds(&mut self) -> GenericBounds {
-        let mut lifetimes = Vec::new();
-        while self.check_lifetime() {
-            lifetimes.push(ast::GenericBound::Outlives(self.expect_lifetime()));
-
-            if !self.eat_plus() {
-                break
-            }
-        }
-        lifetimes
-    }
-
-    /// Matches `typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?`.
-    fn parse_ty_param(&mut self,
-                      preceding_attrs: Vec<Attribute>)
-                      -> PResult<'a, GenericParam> {
-        let ident = self.parse_ident()?;
-
-        // Parse optional colon and param bounds.
-        let bounds = if self.eat(&token::Colon) {
-            self.parse_generic_bounds(Some(self.prev_span))?
-        } else {
-            Vec::new()
-        };
-
-        let default = if self.eat(&token::Eq) {
-            Some(self.parse_ty()?)
-        } else {
-            None
-        };
-
-        Ok(GenericParam {
-            ident,
-            id: ast::DUMMY_NODE_ID,
-            attrs: preceding_attrs.into(),
-            bounds,
-            kind: GenericParamKind::Type {
-                default,
-            },
-            is_placeholder: false
-        })
-    }
-
-    fn parse_const_param(&mut self, preceding_attrs: Vec<Attribute>) -> PResult<'a, GenericParam> {
-        let lo = self.token.span;
-
-        self.expect_keyword(kw::Const)?;
-        let ident = self.parse_ident()?;
-        self.expect(&token::Colon)?;
-        let ty = self.parse_ty()?;
-
-        self.sess.gated_spans.gate(sym::const_generics, lo.to(self.prev_span));
-
-        Ok(GenericParam {
-            ident,
-            id: ast::DUMMY_NODE_ID,
-            attrs: preceding_attrs.into(),
-            bounds: Vec::new(),
-            kind: GenericParamKind::Const {
-                ty,
-            },
-            is_placeholder: false
-        })
-    }
-
-    /// Parses a (possibly empty) list of lifetime and type parameters, possibly including
-    /// a trailing comma and erroneous trailing attributes.
-    pub(super) fn parse_generic_params(&mut self) -> PResult<'a, Vec<ast::GenericParam>> {
-        let mut params = Vec::new();
-        loop {
-            let attrs = self.parse_outer_attributes()?;
-            if self.check_lifetime() {
-                let lifetime = self.expect_lifetime();
-                // Parse lifetime parameter.
-                let bounds = if self.eat(&token::Colon) {
-                    self.parse_lt_param_bounds()
-                } else {
-                    Vec::new()
-                };
-                params.push(ast::GenericParam {
-                    ident: lifetime.ident,
-                    id: lifetime.id,
-                    attrs: attrs.into(),
-                    bounds,
-                    kind: ast::GenericParamKind::Lifetime,
-                    is_placeholder: false
-                });
-            } else if self.check_keyword(kw::Const) {
-                // Parse const parameter.
-                params.push(self.parse_const_param(attrs)?);
-            } else if self.check_ident() {
-                // Parse type parameter.
-                params.push(self.parse_ty_param(attrs)?);
-            } else if self.token.can_begin_type() {
-                // Trying to write an associated type bound? (#26271)
-                let snapshot = self.clone();
-                match self.parse_ty_where_predicate() {
-                    Ok(where_predicate) => {
-                        self.struct_span_err(
-                            where_predicate.span(),
-                            "bounds on associated types do not belong here",
-                        )
-                        .span_label(where_predicate.span(), "belongs in `where` clause")
-                        .emit();
-                    }
-                    Err(mut err) => {
-                        err.cancel();
-                        std::mem::replace(self, snapshot);
-                        break
-                    }
-                }
-            } else {
-                // Check for trailing attributes and stop parsing.
-                if !attrs.is_empty() {
-                    if !params.is_empty() {
-                        self.struct_span_err(
-                            attrs[0].span,
-                            "trailing attribute after generic parameter",
-                        )
-                        .span_label(attrs[0].span, "attributes must go before parameters")
-                        .emit();
-                    } else {
-                        self.struct_span_err(
-                            attrs[0].span,
-                            &format!("attribute without generic parameters"),
-                        )
-                        .span_label(
-                            attrs[0].span,
-                            "attributes are only permitted when preceding parameters",
-                        )
-                        .emit();
-                    }
-                }
-                break
-            }
-
-            if !self.eat(&token::Comma) {
-                break
-            }
-        }
-        Ok(params)
-    }
-
-    /// Parses a set of optional generic type parameter declarations. Where
-    /// clauses are not parsed here, and must be added later via
-    /// `parse_where_clause()`.
-    ///
-    /// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
-    ///                  | ( < lifetimes , typaramseq ( , )? > )
-    /// where   typaramseq = ( typaram ) | ( typaram , typaramseq )
-    pub(super) fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
-        let span_lo = self.token.span;
-        let (params, span) = if self.eat_lt() {
-            let params = self.parse_generic_params()?;
-            self.expect_gt()?;
-            (params, span_lo.to(self.prev_span))
-        } else {
-            (vec![], self.prev_span.between(self.token.span))
-        };
-        Ok(ast::Generics {
-            params,
-            where_clause: WhereClause {
-                predicates: Vec::new(),
-                span: DUMMY_SP,
-            },
-            span,
-        })
-    }
-
-    /// Parses an optional where-clause and places it in `generics`.
-    ///
-    /// ```ignore (only-for-syntax-highlight)
-    /// where T : Trait<U, V> + 'b, 'a : 'b
-    /// ```
-    pub(super) fn parse_where_clause(&mut self) -> PResult<'a, WhereClause> {
-        let mut where_clause = WhereClause {
-            predicates: Vec::new(),
-            span: self.prev_span.to(self.prev_span),
-        };
-
-        if !self.eat_keyword(kw::Where) {
-            return Ok(where_clause);
-        }
-        let lo = self.prev_span;
-
-        // We are considering adding generics to the `where` keyword as an alternative higher-rank
-        // parameter syntax (as in `where<'a>` or `where<T>`. To avoid that being a breaking
-        // change we parse those generics now, but report an error.
-        if self.choose_generics_over_qpath() {
-            let generics = self.parse_generics()?;
-            self.struct_span_err(
-                generics.span,
-                "generic parameters on `where` clauses are reserved for future use",
-            )
-                .span_label(generics.span, "currently unsupported")
-                .emit();
-        }
-
-        loop {
-            let lo = self.token.span;
-            if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
-                let lifetime = self.expect_lifetime();
-                // Bounds starting with a colon are mandatory, but possibly empty.
-                self.expect(&token::Colon)?;
-                let bounds = self.parse_lt_param_bounds();
-                where_clause.predicates.push(ast::WherePredicate::RegionPredicate(
-                    ast::WhereRegionPredicate {
-                        span: lo.to(self.prev_span),
-                        lifetime,
-                        bounds,
-                    }
-                ));
-            } else if self.check_type() {
-                where_clause.predicates.push(self.parse_ty_where_predicate()?);
-            } else {
-                break
-            }
-
-            if !self.eat(&token::Comma) {
-                break
-            }
-        }
-
-        where_clause.span = lo.to(self.prev_span);
-        Ok(where_clause)
-    }
-
-    fn parse_ty_where_predicate(&mut self) -> PResult<'a, ast::WherePredicate> {
-        let lo = self.token.span;
-        // Parse optional `for<'a, 'b>`.
-        // This `for` is parsed greedily and applies to the whole predicate,
-        // the bounded type can have its own `for` applying only to it.
-        // Examples:
-        // * `for<'a> Trait1<'a>: Trait2<'a /* ok */>`
-        // * `(for<'a> Trait1<'a>): Trait2<'a /* not ok */>`
-        // * `for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /* ok */, 'b /* not ok */>`
-        let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
-
-        // Parse type with mandatory colon and (possibly empty) bounds,
-        // or with mandatory equality sign and the second type.
-        let ty = self.parse_ty()?;
-        if self.eat(&token::Colon) {
-            let bounds = self.parse_generic_bounds(Some(self.prev_span))?;
-            Ok(ast::WherePredicate::BoundPredicate(
-                ast::WhereBoundPredicate {
-                    span: lo.to(self.prev_span),
-                    bound_generic_params: lifetime_defs,
-                    bounded_ty: ty,
-                    bounds,
-                }
-            ))
-        // FIXME: Decide what should be used here, `=` or `==`.
-        // FIXME: We are just dropping the binders in lifetime_defs on the floor here.
-        } else if self.eat(&token::Eq) || self.eat(&token::EqEq) {
-            let rhs_ty = self.parse_ty()?;
-            Ok(ast::WherePredicate::EqPredicate(
-                ast::WhereEqPredicate {
-                    span: lo.to(self.prev_span),
-                    lhs_ty: ty,
-                    rhs_ty,
-                    id: ast::DUMMY_NODE_ID,
-                }
-            ))
-        } else {
-            self.unexpected()
-        }
-    }
-
-    pub(super) fn choose_generics_over_qpath(&self) -> bool {
-        // There's an ambiguity between generic parameters and qualified paths in impls.
-        // If we see `<` it may start both, so we have to inspect some following tokens.
-        // The following combinations can only start generics,
-        // but not qualified paths (with one exception):
-        //     `<` `>` - empty generic parameters
-        //     `<` `#` - generic parameters with attributes
-        //     `<` (LIFETIME|IDENT) `>` - single generic parameter
-        //     `<` (LIFETIME|IDENT) `,` - first generic parameter in a list
-        //     `<` (LIFETIME|IDENT) `:` - generic parameter with bounds
-        //     `<` (LIFETIME|IDENT) `=` - generic parameter with a default
-        //     `<` const                - generic const parameter
-        // The only truly ambiguous case is
-        //     `<` IDENT `>` `::` IDENT ...
-        // we disambiguate it in favor of generics (`impl<T> ::absolute::Path<T> { ... }`)
-        // because this is what almost always expected in practice, qualified paths in impls
-        // (`impl <Type>::AssocTy { ... }`) aren't even allowed by type checker at the moment.
-        self.token == token::Lt &&
-            (self.look_ahead(1, |t| t == &token::Pound || t == &token::Gt) ||
-             self.look_ahead(1, |t| t.is_lifetime() || t.is_ident()) &&
-                self.look_ahead(2, |t| t == &token::Gt || t == &token::Comma ||
-                                       t == &token::Colon || t == &token::Eq) ||
-            self.is_keyword_ahead(1, &[kw::Const]))
-    }
-}
diff --git a/src/libsyntax/parse/parser/item.rs b/src/libsyntax/parse/parser/item.rs
deleted file mode 100644
index 531ad532a54..00000000000
--- a/src/libsyntax/parse/parser/item.rs
+++ /dev/null
@@ -1,2237 +0,0 @@
-use super::{Parser, PathStyle};
-use super::diagnostics::{Error, dummy_arg, ConsumeClosingDelim};
-
-use crate::maybe_whole;
-use crate::ptr::P;
-use crate::ast::{self, Abi, DUMMY_NODE_ID, Ident, Attribute, AttrKind, AttrStyle, AnonConst, Item};
-use crate::ast::{ItemKind, ImplItem, ImplItemKind, TraitItem, TraitItemKind, UseTree, UseTreeKind};
-use crate::ast::{PathSegment, IsAuto, Constness, IsAsync, Unsafety, Defaultness};
-use crate::ast::{Visibility, VisibilityKind, Mutability, FnHeader, ForeignItem, ForeignItemKind};
-use crate::ast::{Ty, TyKind, Generics, GenericBounds, TraitRef, EnumDef, VariantData, StructField};
-use crate::ast::{Mac, MacDelimiter, Block, BindingMode, FnDecl, FnSig, SelfKind, Param};
-use crate::parse::token;
-use crate::tokenstream::{TokenTree, TokenStream};
-use crate::symbol::{kw, sym};
-use crate::source_map::{self, respan, Span};
-use crate::ThinVec;
-
-use log::debug;
-use std::mem;
-use errors::{PResult, Applicability, DiagnosticBuilder, DiagnosticId, StashKey};
-use syntax_pos::BytePos;
-
-/// Whether the type alias or associated type is a concrete type or an opaque type.
-#[derive(Debug)]
-pub(super) enum AliasKind {
-    /// Just a new name for the same type.
-    Weak(P<Ty>),
-    /// Only trait impls of the type will be usable, not the actual type itself.
-    OpaqueTy(GenericBounds),
-}
-
-pub(super) type ItemInfo = (Ident, ItemKind, Option<Vec<Attribute>>);
-
-impl<'a> Parser<'a> {
-    pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> {
-        let attrs = self.parse_outer_attributes()?;
-        self.parse_item_(attrs, true, false)
-    }
-
-    pub(super) fn parse_item_(
-        &mut self,
-        attrs: Vec<Attribute>,
-        macros_allowed: bool,
-        attributes_allowed: bool,
-    ) -> PResult<'a, Option<P<Item>>> {
-        let mut unclosed_delims = vec![];
-        let (ret, tokens) = self.collect_tokens(|this| {
-            let item = this.parse_item_implementation(attrs, macros_allowed, attributes_allowed);
-            unclosed_delims.append(&mut this.unclosed_delims);
-            item
-        })?;
-        self.unclosed_delims.append(&mut unclosed_delims);
-
-        // Once we've parsed an item and recorded the tokens we got while
-        // parsing we may want to store `tokens` into the item we're about to
-        // return. Note, though, that we specifically didn't capture tokens
-        // related to outer attributes. The `tokens` field here may later be
-        // used with procedural macros to convert this item back into a token
-        // stream, but during expansion we may be removing attributes as we go
-        // along.
-        //
-        // If we've got inner attributes then the `tokens` we've got above holds
-        // these inner attributes. If an inner attribute is expanded we won't
-        // actually remove it from the token stream, so we'll just keep yielding
-        // it (bad!). To work around this case for now we just avoid recording
-        // `tokens` if we detect any inner attributes. This should help keep
-        // expansion correct, but we should fix this bug one day!
-        Ok(ret.map(|item| {
-            item.map(|mut i| {
-                if !i.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
-                    i.tokens = Some(tokens);
-                }
-                i
-            })
-        }))
-    }
-
-    /// Parses one of the items allowed by the flags.
-    fn parse_item_implementation(
-        &mut self,
-        attrs: Vec<Attribute>,
-        macros_allowed: bool,
-        attributes_allowed: bool,
-    ) -> PResult<'a, Option<P<Item>>> {
-        maybe_whole!(self, NtItem, |item| {
-            let mut item = item.into_inner();
-            let mut attrs = attrs;
-            mem::swap(&mut item.attrs, &mut attrs);
-            item.attrs.extend(attrs);
-            Some(P(item))
-        });
-
-        let lo = self.token.span;
-
-        let vis = self.parse_visibility(false)?;
-
-        if self.eat_keyword(kw::Use) {
-            // USE ITEM
-            let item_ = ItemKind::Use(P(self.parse_use_tree()?));
-            self.expect_semi()?;
-
-            let span = lo.to(self.prev_span);
-            let item = self.mk_item(span, Ident::invalid(), item_, vis, attrs);
-            return Ok(Some(item));
-        }
-
-        if self.eat_keyword(kw::Extern) {
-            let extern_sp = self.prev_span;
-            if self.eat_keyword(kw::Crate) {
-                return Ok(Some(self.parse_item_extern_crate(lo, vis, attrs)?));
-            }
-
-            let abi = self.parse_opt_abi()?;
-
-            if self.eat_keyword(kw::Fn) {
-                // EXTERN FUNCTION ITEM
-                let fn_span = self.prev_span;
-                let header = FnHeader {
-                    unsafety: Unsafety::Normal,
-                    asyncness: respan(fn_span, IsAsync::NotAsync),
-                    constness: respan(fn_span, Constness::NotConst),
-                    abi,
-                };
-                return self.parse_item_fn(lo, vis, attrs, header);
-            } else if self.check(&token::OpenDelim(token::Brace)) {
-                return Ok(Some(
-                    self.parse_item_foreign_mod(lo, abi, vis, attrs, extern_sp)?,
-                ));
-            }
-
-            self.unexpected()?;
-        }
-
-        if self.is_static_global() {
-            self.bump();
-            // STATIC ITEM
-            let m = self.parse_mutability();
-            let info = self.parse_item_const(Some(m))?;
-            return self.mk_item_with_info(attrs, lo, vis, info);
-        }
-
-        if self.eat_keyword(kw::Const) {
-            let const_span = self.prev_span;
-            if [kw::Fn, kw::Unsafe, kw::Extern].iter().any(|k| self.check_keyword(*k)) {
-                // CONST FUNCTION ITEM
-                let unsafety = self.parse_unsafety();
-
-                if self.check_keyword(kw::Extern) {
-                    self.sess.gated_spans.gate(sym::const_extern_fn, lo.to(self.token.span));
-                }
-                let abi = self.parse_extern_abi()?;
-                self.bump(); // `fn`
-
-                let header = FnHeader {
-                    unsafety,
-                    asyncness: respan(const_span, IsAsync::NotAsync),
-                    constness: respan(const_span, Constness::Const),
-                    abi,
-                };
-                return self.parse_item_fn(lo, vis, attrs, header);
-            }
-
-            // CONST ITEM
-            if self.eat_keyword(kw::Mut) {
-                let prev_span = self.prev_span;
-                self.struct_span_err(prev_span, "const globals cannot be mutable")
-                    .span_label(prev_span, "cannot be mutable")
-                    .span_suggestion(
-                        const_span,
-                        "you might want to declare a static instead",
-                        "static".to_owned(),
-                        Applicability::MaybeIncorrect,
-                    )
-                    .emit();
-            }
-
-            let info = self.parse_item_const(None)?;
-            return self.mk_item_with_info(attrs, lo, vis, info);
-        }
-
-        // Parses `async unsafe? fn`.
-        if self.check_keyword(kw::Async) {
-            let async_span = self.token.span;
-            if self.is_keyword_ahead(1, &[kw::Fn])
-                || self.is_keyword_ahead(2, &[kw::Fn])
-            {
-                // ASYNC FUNCTION ITEM
-                self.bump(); // `async`
-                let unsafety = self.parse_unsafety(); // `unsafe`?
-                self.expect_keyword(kw::Fn)?; // `fn`
-                let fn_span = self.prev_span;
-                let asyncness = respan(async_span, IsAsync::Async {
-                    closure_id: DUMMY_NODE_ID,
-                    return_impl_trait_id: DUMMY_NODE_ID,
-                });
-                self.ban_async_in_2015(async_span);
-                let header = FnHeader {
-                    unsafety,
-                    asyncness,
-                    constness: respan(fn_span, Constness::NotConst),
-                    abi: Abi::new(sym::Rust, fn_span),
-                };
-                return self.parse_item_fn(lo, vis, attrs, header);
-            }
-        }
-
-        if self.check_keyword(kw::Unsafe) &&
-            self.is_keyword_ahead(1, &[kw::Trait, kw::Auto])
-        {
-            // UNSAFE TRAIT ITEM
-            self.bump(); // `unsafe`
-            let info = self.parse_item_trait(lo, Unsafety::Unsafe)?;
-            return self.mk_item_with_info(attrs, lo, vis, info);
-        }
-
-        if self.check_keyword(kw::Impl) ||
-           self.check_keyword(kw::Unsafe) &&
-                self.is_keyword_ahead(1, &[kw::Impl]) ||
-           self.check_keyword(kw::Default) &&
-                self.is_keyword_ahead(1, &[kw::Impl, kw::Unsafe])
-        {
-            // IMPL ITEM
-            let defaultness = self.parse_defaultness();
-            let unsafety = self.parse_unsafety();
-            self.expect_keyword(kw::Impl)?;
-            let info = self.parse_item_impl(unsafety, defaultness)?;
-            return self.mk_item_with_info(attrs, lo, vis, info);
-        }
-
-        if self.check_keyword(kw::Fn) {
-            // FUNCTION ITEM
-            self.bump();
-            let fn_span = self.prev_span;
-            let header = FnHeader {
-                unsafety: Unsafety::Normal,
-                asyncness: respan(fn_span, IsAsync::NotAsync),
-                constness: respan(fn_span, Constness::NotConst),
-                abi: Abi::new(sym::Rust, fn_span),
-            };
-            return self.parse_item_fn(lo, vis, attrs, header);
-        }
-
-        if self.check_keyword(kw::Unsafe)
-            && self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace))
-        {
-            // UNSAFE FUNCTION ITEM
-            self.bump(); // `unsafe`
-            // `{` is also expected after `unsafe`; in case of error, include it in the diagnostic.
-            self.check(&token::OpenDelim(token::Brace));
-            let abi = self.parse_extern_abi()?;
-            self.expect_keyword(kw::Fn)?;
-            let fn_span = self.prev_span;
-            let header = FnHeader {
-                unsafety: Unsafety::Unsafe,
-                asyncness: respan(fn_span, IsAsync::NotAsync),
-                constness: respan(fn_span, Constness::NotConst),
-                abi,
-            };
-            return self.parse_item_fn(lo, vis, attrs, header);
-        }
-
-        if self.eat_keyword(kw::Mod) {
-            // MODULE ITEM
-            let info = self.parse_item_mod(&attrs[..])?;
-            return self.mk_item_with_info(attrs, lo, vis, info);
-        }
-
-        if let Some(type_) = self.eat_type() {
-            let (ident, alias, generics) = type_?;
-            // TYPE ITEM
-            let item_ = match alias {
-                AliasKind::Weak(ty) => ItemKind::TyAlias(ty, generics),
-                AliasKind::OpaqueTy(bounds) => ItemKind::OpaqueTy(bounds, generics),
-            };
-            let span = lo.to(self.prev_span);
-            return Ok(Some(self.mk_item(span, ident, item_, vis, attrs)));
-        }
-
-        if self.eat_keyword(kw::Enum) {
-            // ENUM ITEM
-            let info = self.parse_item_enum()?;
-            return self.mk_item_with_info(attrs, lo, vis, info);
-        }
-
-        if self.check_keyword(kw::Trait)
-            || (self.check_keyword(kw::Auto)
-                && self.is_keyword_ahead(1, &[kw::Trait]))
-        {
-            // TRAIT ITEM
-            let info = self.parse_item_trait(lo, Unsafety::Normal)?;
-            return self.mk_item_with_info(attrs, lo, vis, info);
-        }
-
-        if self.eat_keyword(kw::Struct) {
-            // STRUCT ITEM
-            let info = self.parse_item_struct()?;
-            return self.mk_item_with_info(attrs, lo, vis, info);
-        }
-
-        if self.is_union_item() {
-            // UNION ITEM
-            self.bump();
-            let info = self.parse_item_union()?;
-            return self.mk_item_with_info(attrs, lo, vis, info);
-        }
-
-        if let Some(macro_def) = self.eat_macro_def(&attrs, &vis, lo)? {
-            return Ok(Some(macro_def));
-        }
-
-        // Verify whether we have encountered a struct or method definition where the user forgot to
-        // add the `struct` or `fn` keyword after writing `pub`: `pub S {}`
-        if vis.node.is_pub() &&
-            self.check_ident() &&
-            self.look_ahead(1, |t| *t != token::Not)
-        {
-            // Space between `pub` keyword and the identifier
-            //
-            //     pub   S {}
-            //        ^^^ `sp` points here
-            let sp = self.prev_span.between(self.token.span);
-            let full_sp = self.prev_span.to(self.token.span);
-            let ident_sp = self.token.span;
-            if self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) {
-                // possible public struct definition where `struct` was forgotten
-                let ident = self.parse_ident().unwrap();
-                let msg = format!("add `struct` here to parse `{}` as a public struct",
-                                  ident);
-                let mut err = self.diagnostic()
-                    .struct_span_err(sp, "missing `struct` for struct definition");
-                err.span_suggestion_short(
-                    sp, &msg, " struct ".into(), Applicability::MaybeIncorrect // speculative
-                );
-                return Err(err);
-            } else if self.look_ahead(1, |t| *t == token::OpenDelim(token::Paren)) {
-                let ident = self.parse_ident().unwrap();
-                self.bump();  // `(`
-                let kw_name = self.recover_first_param();
-                self.consume_block(token::Paren, ConsumeClosingDelim::Yes);
-                let (kw, kw_name, ambiguous) = if self.check(&token::RArrow) {
-                    self.eat_to_tokens(&[&token::OpenDelim(token::Brace)]);
-                    self.bump();  // `{`
-                    ("fn", kw_name, false)
-                } else if self.check(&token::OpenDelim(token::Brace)) {
-                    self.bump();  // `{`
-                    ("fn", kw_name, false)
-                } else if self.check(&token::Colon) {
-                    let kw = "struct";
-                    (kw, kw, false)
-                } else {
-                    ("fn` or `struct", "function or struct", true)
-                };
-
-                let msg = format!("missing `{}` for {} definition", kw, kw_name);
-                let mut err = self.diagnostic().struct_span_err(sp, &msg);
-                if !ambiguous {
-                    self.consume_block(token::Brace, ConsumeClosingDelim::Yes);
-                    let suggestion = format!("add `{}` here to parse `{}` as a public {}",
-                                             kw,
-                                             ident,
-                                             kw_name);
-                    err.span_suggestion_short(
-                        sp, &suggestion, format!(" {} ", kw), Applicability::MachineApplicable
-                    );
-                } else {
-                    if let Ok(snippet) = self.span_to_snippet(ident_sp) {
-                        err.span_suggestion(
-                            full_sp,
-                            "if you meant to call a macro, try",
-                            format!("{}!", snippet),
-                            // this is the `ambiguous` conditional branch
-                            Applicability::MaybeIncorrect
-                        );
-                    } else {
-                        err.help("if you meant to call a macro, remove the `pub` \
-                                  and add a trailing `!` after the identifier");
-                    }
-                }
-                return Err(err);
-            } else if self.look_ahead(1, |t| *t == token::Lt) {
-                let ident = self.parse_ident().unwrap();
-                self.eat_to_tokens(&[&token::Gt]);
-                self.bump();  // `>`
-                let (kw, kw_name, ambiguous) = if self.eat(&token::OpenDelim(token::Paren)) {
-                    ("fn", self.recover_first_param(), false)
-                } else if self.check(&token::OpenDelim(token::Brace)) {
-                    ("struct", "struct", false)
-                } else {
-                    ("fn` or `struct", "function or struct", true)
-                };
-                let msg = format!("missing `{}` for {} definition", kw, kw_name);
-                let mut err = self.diagnostic().struct_span_err(sp, &msg);
-                if !ambiguous {
-                    err.span_suggestion_short(
-                        sp,
-                        &format!("add `{}` here to parse `{}` as a public {}", kw, ident, kw_name),
-                        format!(" {} ", kw),
-                        Applicability::MachineApplicable,
-                    );
-                }
-                return Err(err);
-            }
-        }
-        self.parse_macro_use_or_failure(attrs, macros_allowed, attributes_allowed, lo, vis)
-    }
-
-    pub(super) fn mk_item_with_info(
-        &self,
-        attrs: Vec<Attribute>,
-        lo: Span,
-        vis: Visibility,
-        info: ItemInfo,
-    ) -> PResult<'a, Option<P<Item>>> {
-        let (ident, item, extra_attrs) = info;
-        let span = lo.to(self.prev_span);
-        let attrs = Self::maybe_append(attrs, extra_attrs);
-        Ok(Some(self.mk_item(span, ident, item, vis, attrs)))
-    }
-
-    fn maybe_append<T>(mut lhs: Vec<T>, mut rhs: Option<Vec<T>>) -> Vec<T> {
-        if let Some(ref mut rhs) = rhs {
-            lhs.append(rhs);
-        }
-        lhs
-    }
-
-    /// This is the fall-through for parsing items.
-    fn parse_macro_use_or_failure(
-        &mut self,
-        attrs: Vec<Attribute> ,
-        macros_allowed: bool,
-        attributes_allowed: bool,
-        lo: Span,
-        visibility: Visibility
-    ) -> PResult<'a, Option<P<Item>>> {
-        if macros_allowed && self.token.is_path_start() &&
-                !(self.is_async_fn() && self.token.span.rust_2015()) {
-            // MACRO INVOCATION ITEM
-
-            let prev_span = self.prev_span;
-            self.complain_if_pub_macro(&visibility.node, prev_span);
-
-            let mac_lo = self.token.span;
-
-            // Item macro
-            let path = self.parse_path(PathStyle::Mod)?;
-            self.expect(&token::Not)?;
-            let (delim, tts) = self.expect_delimited_token_tree()?;
-            if delim != MacDelimiter::Brace && !self.eat(&token::Semi) {
-                self.report_invalid_macro_expansion_item();
-            }
-
-            let hi = self.prev_span;
-            let mac = Mac {
-                path,
-                tts,
-                delim,
-                span: mac_lo.to(hi),
-                prior_type_ascription: self.last_type_ascription,
-            };
-            let item =
-                self.mk_item(lo.to(hi), Ident::invalid(), ItemKind::Mac(mac), visibility, attrs);
-            return Ok(Some(item));
-        }
-
-        // FAILURE TO PARSE ITEM
-        match visibility.node {
-            VisibilityKind::Inherited => {}
-            _ => {
-                return Err(self.span_fatal(self.prev_span, "unmatched visibility `pub`"));
-            }
-        }
-
-        if !attributes_allowed && !attrs.is_empty() {
-            self.expected_item_err(&attrs)?;
-        }
-        Ok(None)
-    }
-
-    /// Emits an expected-item-after-attributes error.
-    fn expected_item_err(&mut self, attrs: &[Attribute]) -> PResult<'a,  ()> {
-        let message = match attrs.last() {
-            Some(&Attribute { kind: AttrKind::DocComment(_), .. }) =>
-                "expected item after doc comment",
-            _ =>
-                "expected item after attributes",
-        };
-
-        let mut err = self.diagnostic().struct_span_err(self.prev_span, message);
-        if attrs.last().unwrap().is_doc_comment() {
-            err.span_label(self.prev_span, "this doc comment doesn't document anything");
-        }
-        Err(err)
-    }
-
-    pub(super) fn is_async_fn(&self) -> bool {
-        self.token.is_keyword(kw::Async) &&
-            self.is_keyword_ahead(1, &[kw::Fn])
-    }
-
-    /// Parses a macro invocation inside a `trait`, `impl` or `extern` block.
-    fn parse_assoc_macro_invoc(&mut self, item_kind: &str, vis: Option<&Visibility>,
-                               at_end: &mut bool) -> PResult<'a, Option<Mac>>
-    {
-        if self.token.is_path_start() &&
-                !(self.is_async_fn() && self.token.span.rust_2015()) {
-            let prev_span = self.prev_span;
-            let lo = self.token.span;
-            let path = self.parse_path(PathStyle::Mod)?;
-
-            if path.segments.len() == 1 {
-                if !self.eat(&token::Not) {
-                    return Err(self.missing_assoc_item_kind_err(item_kind, prev_span));
-                }
-            } else {
-                self.expect(&token::Not)?;
-            }
-
-            if let Some(vis) = vis {
-                self.complain_if_pub_macro(&vis.node, prev_span);
-            }
-
-            *at_end = true;
-
-            // eat a matched-delimiter token tree:
-            let (delim, tts) = self.expect_delimited_token_tree()?;
-            if delim != MacDelimiter::Brace {
-                self.expect_semi()?;
-            }
-
-            Ok(Some(Mac {
-                path,
-                tts,
-                delim,
-                span: lo.to(self.prev_span),
-                prior_type_ascription: self.last_type_ascription,
-            }))
-        } else {
-            Ok(None)
-        }
-    }
-
-    fn missing_assoc_item_kind_err(&self, item_type: &str, prev_span: Span)
-                                   -> DiagnosticBuilder<'a>
-    {
-        let expected_kinds = if item_type == "extern" {
-            "missing `fn`, `type`, or `static`"
-        } else {
-            "missing `fn`, `type`, or `const`"
-        };
-
-        // Given this code `path(`, it seems like this is not
-        // setting the visibility of a macro invocation, but rather
-        // a mistyped method declaration.
-        // Create a diagnostic pointing out that `fn` is missing.
-        //
-        // x |     pub path(&self) {
-        //   |        ^ missing `fn`, `type`, or `const`
-        //     pub  path(
-        //        ^^ `sp` below will point to this
-        let sp = prev_span.between(self.prev_span);
-        let mut err = self.diagnostic().struct_span_err(
-            sp,
-            &format!("{} for {}-item declaration",
-                     expected_kinds, item_type));
-        err.span_label(sp, expected_kinds);
-        err
-    }
-
-    /// Parses an implementation item, `impl` keyword is already parsed.
-    ///
-    ///    impl<'a, T> TYPE { /* impl items */ }
-    ///    impl<'a, T> TRAIT for TYPE { /* impl items */ }
-    ///    impl<'a, T> !TRAIT for TYPE { /* impl items */ }
-    ///
-    /// We actually parse slightly more relaxed grammar for better error reporting and recovery.
-    ///     `impl` GENERICS `!`? TYPE `for`? (TYPE | `..`) (`where` PREDICATES)? `{` BODY `}`
-    ///     `impl` GENERICS `!`? TYPE (`where` PREDICATES)? `{` BODY `}`
-    fn parse_item_impl(&mut self, unsafety: Unsafety, defaultness: Defaultness)
-                       -> PResult<'a, ItemInfo> {
-        // First, parse generic parameters if necessary.
-        let mut generics = if self.choose_generics_over_qpath() {
-            self.parse_generics()?
-        } else {
-            Generics::default()
-        };
-
-        // Disambiguate `impl !Trait for Type { ... }` and `impl ! { ... }` for the never type.
-        let polarity = if self.check(&token::Not) && self.look_ahead(1, |t| t.can_begin_type()) {
-            self.bump(); // `!`
-            ast::ImplPolarity::Negative
-        } else {
-            ast::ImplPolarity::Positive
-        };
-
-        // Parse both types and traits as a type, then reinterpret if necessary.
-        let err_path = |span| ast::Path::from_ident(Ident::new(kw::Invalid, span));
-        let ty_first = if self.token.is_keyword(kw::For) &&
-                          self.look_ahead(1, |t| t != &token::Lt) {
-            let span = self.prev_span.between(self.token.span);
-            self.struct_span_err(span, "missing trait in a trait impl").emit();
-            P(Ty { kind: TyKind::Path(None, err_path(span)), span, id: DUMMY_NODE_ID })
-        } else {
-            self.parse_ty()?
-        };
-
-        // If `for` is missing we try to recover.
-        let has_for = self.eat_keyword(kw::For);
-        let missing_for_span = self.prev_span.between(self.token.span);
-
-        let ty_second = if self.token == token::DotDot {
-            // We need to report this error after `cfg` expansion for compatibility reasons
-            self.bump(); // `..`, do not add it to expected tokens
-            Some(self.mk_ty(self.prev_span, TyKind::Err))
-        } else if has_for || self.token.can_begin_type() {
-            Some(self.parse_ty()?)
-        } else {
-            None
-        };
-
-        generics.where_clause = self.parse_where_clause()?;
-
-        let (impl_items, attrs) = self.parse_impl_body()?;
-
-        let item_kind = match ty_second {
-            Some(ty_second) => {
-                // impl Trait for Type
-                if !has_for {
-                    self.struct_span_err(missing_for_span, "missing `for` in a trait impl")
-                        .span_suggestion_short(
-                            missing_for_span,
-                            "add `for` here",
-                            " for ".to_string(),
-                            Applicability::MachineApplicable,
-                        ).emit();
-                }
-
-                let ty_first = ty_first.into_inner();
-                let path = match ty_first.kind {
-                    // This notably includes paths passed through `ty` macro fragments (#46438).
-                    TyKind::Path(None, path) => path,
-                    _ => {
-                        self.span_err(ty_first.span, "expected a trait, found type");
-                        err_path(ty_first.span)
-                    }
-                };
-                let trait_ref = TraitRef { path, ref_id: ty_first.id };
-
-                ItemKind::Impl(unsafety, polarity, defaultness,
-                               generics, Some(trait_ref), ty_second, impl_items)
-            }
-            None => {
-                // impl Type
-                ItemKind::Impl(unsafety, polarity, defaultness,
-                               generics, None, ty_first, impl_items)
-            }
-        };
-
-        Ok((Ident::invalid(), item_kind, Some(attrs)))
-    }
-
-    fn parse_impl_body(&mut self) -> PResult<'a, (Vec<ImplItem>, Vec<Attribute>)> {
-        self.expect(&token::OpenDelim(token::Brace))?;
-        let attrs = self.parse_inner_attributes()?;
-
-        let mut impl_items = Vec::new();
-        while !self.eat(&token::CloseDelim(token::Brace)) {
-            let mut at_end = false;
-            match self.parse_impl_item(&mut at_end) {
-                Ok(impl_item) => impl_items.push(impl_item),
-                Err(mut err) => {
-                    err.emit();
-                    if !at_end {
-                        self.consume_block(token::Brace, ConsumeClosingDelim::Yes);
-                        break;
-                    }
-                }
-            }
-        }
-        Ok((impl_items, attrs))
-    }
-
-    /// Parses an impl item.
-    pub fn parse_impl_item(&mut self, at_end: &mut bool) -> PResult<'a, ImplItem> {
-        maybe_whole!(self, NtImplItem, |x| x);
-        let attrs = self.parse_outer_attributes()?;
-        let mut unclosed_delims = vec![];
-        let (mut item, tokens) = self.collect_tokens(|this| {
-            let item = this.parse_impl_item_(at_end, attrs);
-            unclosed_delims.append(&mut this.unclosed_delims);
-            item
-        })?;
-        self.unclosed_delims.append(&mut unclosed_delims);
-
-        // See `parse_item` for why this clause is here.
-        if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
-            item.tokens = Some(tokens);
-        }
-        Ok(item)
-    }
-
-    fn parse_impl_item_(
-        &mut self,
-        at_end: &mut bool,
-        mut attrs: Vec<Attribute>,
-    ) -> PResult<'a, ImplItem> {
-        let lo = self.token.span;
-        let vis = self.parse_visibility(false)?;
-        let defaultness = self.parse_defaultness();
-        let (name, kind, generics) = if let Some(type_) = self.eat_type() {
-            let (name, alias, generics) = type_?;
-            let kind = match alias {
-                AliasKind::Weak(typ) => ast::ImplItemKind::TyAlias(typ),
-                AliasKind::OpaqueTy(bounds) => ast::ImplItemKind::OpaqueTy(bounds),
-            };
-            (name, kind, generics)
-        } else if self.is_const_item() {
-            self.parse_impl_const()?
-        } else if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(&vis), at_end)? {
-            // FIXME: code copied from `parse_macro_use_or_failure` -- use abstraction!
-            (Ident::invalid(), ast::ImplItemKind::Macro(mac), Generics::default())
-        } else {
-            let (name, inner_attrs, generics, kind) = self.parse_impl_method(at_end)?;
-            attrs.extend(inner_attrs);
-            (name, kind, generics)
-        };
-
-        Ok(ImplItem {
-            id: DUMMY_NODE_ID,
-            span: lo.to(self.prev_span),
-            ident: name,
-            vis,
-            defaultness,
-            attrs,
-            generics,
-            kind,
-            tokens: None,
-        })
-    }
-
-    /// Parses defaultness (i.e., `default` or nothing).
-    fn parse_defaultness(&mut self) -> Defaultness {
-        // `pub` is included for better error messages
-        if self.check_keyword(kw::Default) &&
-            self.is_keyword_ahead(1, &[
-                kw::Impl,
-                kw::Const,
-                kw::Async,
-                kw::Fn,
-                kw::Unsafe,
-                kw::Extern,
-                kw::Type,
-                kw::Pub,
-            ])
-        {
-            self.bump(); // `default`
-            Defaultness::Default
-        } else {
-            Defaultness::Final
-        }
-    }
-
-    /// Returns `true` if we are looking at `const ID`
-    /// (returns `false` for things like `const fn`, etc.).
-    fn is_const_item(&self) -> bool {
-        self.token.is_keyword(kw::Const) &&
-            !self.is_keyword_ahead(1, &[kw::Fn, kw::Unsafe])
-    }
-
-    /// This parses the grammar:
-    ///     ImplItemConst = "const" Ident ":" Ty "=" Expr ";"
-    fn parse_impl_const(&mut self) -> PResult<'a, (Ident, ImplItemKind, Generics)> {
-        self.expect_keyword(kw::Const)?;
-        let name = self.parse_ident()?;
-        self.expect(&token::Colon)?;
-        let typ = self.parse_ty()?;
-        self.expect(&token::Eq)?;
-        let expr = self.parse_expr()?;
-        self.expect_semi()?;
-        Ok((name, ImplItemKind::Const(typ, expr), Generics::default()))
-    }
-
-    /// Parses `auto? trait Foo { ... }` or `trait Foo = Bar;`.
-    fn parse_item_trait(&mut self, lo: Span, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
-        // Parse optional `auto` prefix.
-        let is_auto = if self.eat_keyword(kw::Auto) {
-            IsAuto::Yes
-        } else {
-            IsAuto::No
-        };
-
-        self.expect_keyword(kw::Trait)?;
-        let ident = self.parse_ident()?;
-        let mut tps = self.parse_generics()?;
-
-        // Parse optional colon and supertrait bounds.
-        let had_colon = self.eat(&token::Colon);
-        let span_at_colon = self.prev_span;
-        let bounds = if had_colon {
-            self.parse_generic_bounds(Some(self.prev_span))?
-        } else {
-            Vec::new()
-        };
-
-        let span_before_eq = self.prev_span;
-        if self.eat(&token::Eq) {
-            // It's a trait alias.
-            if had_colon {
-                let span = span_at_colon.to(span_before_eq);
-                self.struct_span_err(span, "bounds are not allowed on trait aliases")
-                    .emit();
-            }
-
-            let bounds = self.parse_generic_bounds(None)?;
-            tps.where_clause = self.parse_where_clause()?;
-            self.expect_semi()?;
-
-            let whole_span = lo.to(self.prev_span);
-            if is_auto == IsAuto::Yes {
-                let msg = "trait aliases cannot be `auto`";
-                self.struct_span_err(whole_span, msg)
-                    .span_label(whole_span, msg)
-                    .emit();
-            }
-            if unsafety != Unsafety::Normal {
-                let msg = "trait aliases cannot be `unsafe`";
-                self.struct_span_err(whole_span, msg)
-                    .span_label(whole_span, msg)
-                    .emit();
-            }
-
-            self.sess.gated_spans.gate(sym::trait_alias, whole_span);
-
-            Ok((ident, ItemKind::TraitAlias(tps, bounds), None))
-        } else {
-            // It's a normal trait.
-            tps.where_clause = self.parse_where_clause()?;
-            self.expect(&token::OpenDelim(token::Brace))?;
-            let mut trait_items = vec![];
-            while !self.eat(&token::CloseDelim(token::Brace)) {
-                if let token::DocComment(_) = self.token.kind {
-                    if self.look_ahead(1,
-                    |tok| tok == &token::CloseDelim(token::Brace)) {
-                        self.diagnostic().struct_span_err_with_code(
-                            self.token.span,
-                            "found a documentation comment that doesn't document anything",
-                            DiagnosticId::Error("E0584".into()),
-                        )
-                        .help(
-                            "doc comments must come before what they document, maybe a \
-                            comment was intended with `//`?",
-                        )
-                        .emit();
-                        self.bump();
-                        continue;
-                    }
-                }
-                let mut at_end = false;
-                match self.parse_trait_item(&mut at_end) {
-                    Ok(item) => trait_items.push(item),
-                    Err(mut e) => {
-                        e.emit();
-                        if !at_end {
-                            self.consume_block(token::Brace, ConsumeClosingDelim::Yes);
-                            break;
-                        }
-                    }
-                }
-            }
-            Ok((ident, ItemKind::Trait(is_auto, unsafety, tps, bounds, trait_items), None))
-        }
-    }
-
-    /// Parses the items in a trait declaration.
-    pub fn parse_trait_item(&mut self, at_end: &mut bool) -> PResult<'a, TraitItem> {
-        maybe_whole!(self, NtTraitItem, |x| x);
-        let attrs = self.parse_outer_attributes()?;
-        let mut unclosed_delims = vec![];
-        let (mut item, tokens) = self.collect_tokens(|this| {
-            let item = this.parse_trait_item_(at_end, attrs);
-            unclosed_delims.append(&mut this.unclosed_delims);
-            item
-        })?;
-        self.unclosed_delims.append(&mut unclosed_delims);
-        // See `parse_item` for why this clause is here.
-        if !item.attrs.iter().any(|attr| attr.style == AttrStyle::Inner) {
-            item.tokens = Some(tokens);
-        }
-        Ok(item)
-    }
-
-    fn parse_trait_item_(
-        &mut self,
-        at_end: &mut bool,
-        mut attrs: Vec<Attribute>,
-    ) -> PResult<'a, TraitItem> {
-        let lo = self.token.span;
-        self.eat_bad_pub();
-        let (name, kind, generics) = if self.eat_keyword(kw::Type) {
-            self.parse_trait_item_assoc_ty()?
-        } else if self.is_const_item() {
-            self.parse_trait_item_const()?
-        } else if let Some(mac) = self.parse_assoc_macro_invoc("trait", None, &mut false)? {
-            // trait item macro.
-            (Ident::invalid(), TraitItemKind::Macro(mac), Generics::default())
-        } else {
-            self.parse_trait_item_method(at_end, &mut attrs)?
-        };
-
-        Ok(TraitItem {
-            id: DUMMY_NODE_ID,
-            ident: name,
-            attrs,
-            generics,
-            kind,
-            span: lo.to(self.prev_span),
-            tokens: None,
-        })
-    }
-
-    fn parse_trait_item_const(&mut self) -> PResult<'a, (Ident, TraitItemKind, Generics)> {
-        self.expect_keyword(kw::Const)?;
-        let ident = self.parse_ident()?;
-        self.expect(&token::Colon)?;
-        let ty = self.parse_ty()?;
-        let default = if self.eat(&token::Eq) {
-            Some(self.parse_expr()?)
-        } else {
-            None
-        };
-        self.expect_semi()?;
-        Ok((ident, TraitItemKind::Const(ty, default), Generics::default()))
-    }
-
-    /// Parses the following grammar:
-    ///
-    ///     TraitItemAssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty]
-    fn parse_trait_item_assoc_ty(&mut self) -> PResult<'a, (Ident, TraitItemKind, Generics)> {
-        let ident = self.parse_ident()?;
-        let mut generics = self.parse_generics()?;
-
-        // Parse optional colon and param bounds.
-        let bounds = if self.eat(&token::Colon) {
-            self.parse_generic_bounds(None)?
-        } else {
-            Vec::new()
-        };
-        generics.where_clause = self.parse_where_clause()?;
-
-        let default = if self.eat(&token::Eq) {
-            Some(self.parse_ty()?)
-        } else {
-            None
-        };
-        self.expect_semi()?;
-
-        Ok((ident, TraitItemKind::Type(bounds, default), generics))
-    }
-
-    /// Parses a `UseTree`.
-    ///
-    /// ```
-    /// USE_TREE = [`::`] `*` |
-    ///            [`::`] `{` USE_TREE_LIST `}` |
-    ///            PATH `::` `*` |
-    ///            PATH `::` `{` USE_TREE_LIST `}` |
-    ///            PATH [`as` IDENT]
-    /// ```
-    fn parse_use_tree(&mut self) -> PResult<'a, UseTree> {
-        let lo = self.token.span;
-
-        let mut prefix = ast::Path { segments: Vec::new(), span: lo.shrink_to_lo() };
-        let kind = if self.check(&token::OpenDelim(token::Brace)) ||
-                      self.check(&token::BinOp(token::Star)) ||
-                      self.is_import_coupler() {
-            // `use *;` or `use ::*;` or `use {...};` or `use ::{...};`
-            let mod_sep_ctxt = self.token.span.ctxt();
-            if self.eat(&token::ModSep) {
-                prefix.segments.push(
-                    PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt))
-                );
-            }
-
-            self.parse_use_tree_glob_or_nested()?
-        } else {
-            // `use path::*;` or `use path::{...};` or `use path;` or `use path as bar;`
-            prefix = self.parse_path(PathStyle::Mod)?;
-
-            if self.eat(&token::ModSep) {
-                self.parse_use_tree_glob_or_nested()?
-            } else {
-                UseTreeKind::Simple(self.parse_rename()?, DUMMY_NODE_ID, DUMMY_NODE_ID)
-            }
-        };
-
-        Ok(UseTree { prefix, kind, span: lo.to(self.prev_span) })
-    }
-
-    /// Parses `*` or `{...}`.
-    fn parse_use_tree_glob_or_nested(&mut self) -> PResult<'a, UseTreeKind> {
-        Ok(if self.eat(&token::BinOp(token::Star)) {
-            UseTreeKind::Glob
-        } else {
-            UseTreeKind::Nested(self.parse_use_tree_list()?)
-        })
-    }
-
-    /// Parses a `UseTreeKind::Nested(list)`.
-    ///
-    /// ```
-    /// USE_TREE_LIST = Ø | (USE_TREE `,`)* USE_TREE [`,`]
-    /// ```
-    fn parse_use_tree_list(&mut self) -> PResult<'a, Vec<(UseTree, ast::NodeId)>> {
-        self.parse_delim_comma_seq(token::Brace, |p| Ok((p.parse_use_tree()?, DUMMY_NODE_ID)))
-            .map(|(r, _)| r)
-    }
-
-    fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
-        if self.eat_keyword(kw::As) {
-            self.parse_ident_or_underscore().map(Some)
-        } else {
-            Ok(None)
-        }
-    }
-
-    fn parse_ident_or_underscore(&mut self) -> PResult<'a, ast::Ident> {
-        match self.token.kind {
-            token::Ident(name, false) if name == kw::Underscore => {
-                let span = self.token.span;
-                self.bump();
-                Ok(Ident::new(name, span))
-            }
-            _ => self.parse_ident(),
-        }
-    }
-
-    /// Parses `extern crate` links.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// extern crate foo;
-    /// extern crate bar as foo;
-    /// ```
-    fn parse_item_extern_crate(
-        &mut self,
-        lo: Span,
-        visibility: Visibility,
-        attrs: Vec<Attribute>
-    ) -> PResult<'a, P<Item>> {
-        // Accept `extern crate name-like-this` for better diagnostics
-        let orig_name = self.parse_crate_name_with_dashes()?;
-        let (item_name, orig_name) = if let Some(rename) = self.parse_rename()? {
-            (rename, Some(orig_name.name))
-        } else {
-            (orig_name, None)
-        };
-        self.expect_semi()?;
-
-        let span = lo.to(self.prev_span);
-        Ok(self.mk_item(span, item_name, ItemKind::ExternCrate(orig_name), visibility, attrs))
-    }
-
-    fn parse_crate_name_with_dashes(&mut self) -> PResult<'a, ast::Ident> {
-        let error_msg = "crate name using dashes are not valid in `extern crate` statements";
-        let suggestion_msg = "if the original crate name uses dashes you need to use underscores \
-                              in the code";
-        let mut ident = if self.token.is_keyword(kw::SelfLower) {
-            self.parse_path_segment_ident()
-        } else {
-            self.parse_ident()
-        }?;
-        let mut idents = vec![];
-        let mut replacement = vec![];
-        let mut fixed_crate_name = false;
-        // Accept `extern crate name-like-this` for better diagnostics.
-        let dash = token::BinOp(token::BinOpToken::Minus);
-        if self.token == dash {  // Do not include `-` as part of the expected tokens list.
-            while self.eat(&dash) {
-                fixed_crate_name = true;
-                replacement.push((self.prev_span, "_".to_string()));
-                idents.push(self.parse_ident()?);
-            }
-        }
-        if fixed_crate_name {
-            let fixed_name_sp = ident.span.to(idents.last().unwrap().span);
-            let mut fixed_name = format!("{}", ident.name);
-            for part in idents {
-                fixed_name.push_str(&format!("_{}", part.name));
-            }
-            ident = Ident::from_str_and_span(&fixed_name, fixed_name_sp);
-
-            self.struct_span_err(fixed_name_sp, error_msg)
-                .span_label(fixed_name_sp, "dash-separated idents are not valid")
-                .multipart_suggestion(suggestion_msg, replacement, Applicability::MachineApplicable)
-                .emit();
-        }
-        Ok(ident)
-    }
-
-    /// Parses `extern` for foreign ABIs modules.
-    ///
-    /// `extern` is expected to have been
-    /// consumed before calling this method.
-    ///
-    /// # Examples
-    ///
-    /// ```ignore (only-for-syntax-highlight)
-    /// extern "C" {}
-    /// extern {}
-    /// ```
-    fn parse_item_foreign_mod(
-        &mut self,
-        lo: Span,
-        abi: Abi,
-        visibility: Visibility,
-        mut attrs: Vec<Attribute>,
-        extern_sp: Span,
-    ) -> PResult<'a, P<Item>> {
-        self.expect(&token::OpenDelim(token::Brace))?;
-
-        attrs.extend(self.parse_inner_attributes()?);
-
-        let mut foreign_items = vec![];
-        while !self.eat(&token::CloseDelim(token::Brace)) {
-            foreign_items.push(self.parse_foreign_item(extern_sp)?);
-        }
-
-        let prev_span = self.prev_span;
-        let m = ast::ForeignMod {
-            abi,
-            items: foreign_items
-        };
-        let invalid = Ident::invalid();
-        Ok(self.mk_item(lo.to(prev_span), invalid, ItemKind::ForeignMod(m), visibility, attrs))
-    }
-
-    /// Parses a foreign item.
-    pub fn parse_foreign_item(&mut self, extern_sp: Span) -> PResult<'a, ForeignItem> {
-        maybe_whole!(self, NtForeignItem, |ni| ni);
-
-        let attrs = self.parse_outer_attributes()?;
-        let lo = self.token.span;
-        let visibility = self.parse_visibility(false)?;
-
-        // FOREIGN STATIC ITEM
-        // Treat `const` as `static` for error recovery, but don't add it to expected tokens.
-        if self.check_keyword(kw::Static) || self.token.is_keyword(kw::Const) {
-            if self.token.is_keyword(kw::Const) {
-                let mut err = self
-                    .struct_span_err(self.token.span, "extern items cannot be `const`");
-
-
-                // The user wrote 'const fn'
-                if self.is_keyword_ahead(1, &[kw::Fn, kw::Unsafe]) {
-                    err.emit();
-                    // Consume `const`
-                    self.bump();
-                    // Consume `unsafe` if present, since `extern` blocks
-                    // don't allow it. This will leave behind a plain 'fn'
-                    self.eat_keyword(kw::Unsafe);
-                    // Treat 'const fn` as a plain `fn` for error recovery purposes.
-                    // We've already emitted an error, so compilation is guaranteed
-                    // to fail
-                    return Ok(self.parse_item_foreign_fn(visibility, lo, attrs, extern_sp)?);
-                }
-                err.span_suggestion(
-                        self.token.span,
-                        "try using a static value",
-                        "static".to_owned(),
-                        Applicability::MachineApplicable
-                );
-                err.emit();
-            }
-            self.bump(); // `static` or `const`
-            return Ok(self.parse_item_foreign_static(visibility, lo, attrs)?);
-        }
-        // FOREIGN FUNCTION ITEM
-        if self.check_keyword(kw::Fn) {
-            return Ok(self.parse_item_foreign_fn(visibility, lo, attrs, extern_sp)?);
-        }
-        // FOREIGN TYPE ITEM
-        if self.check_keyword(kw::Type) {
-            return Ok(self.parse_item_foreign_type(visibility, lo, attrs)?);
-        }
-
-        match self.parse_assoc_macro_invoc("extern", Some(&visibility), &mut false)? {
-            Some(mac) => {
-                Ok(
-                    ForeignItem {
-                        ident: Ident::invalid(),
-                        span: lo.to(self.prev_span),
-                        id: DUMMY_NODE_ID,
-                        attrs,
-                        vis: visibility,
-                        kind: ForeignItemKind::Macro(mac),
-                    }
-                )
-            }
-            None => {
-                if !attrs.is_empty()  {
-                    self.expected_item_err(&attrs)?;
-                }
-
-                self.unexpected()
-            }
-        }
-    }
-
-    /// Parses a static item from a foreign module.
-    /// Assumes that the `static` keyword is already parsed.
-    fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
-                                 -> PResult<'a, ForeignItem> {
-        let mutbl = self.parse_mutability();
-        let ident = self.parse_ident()?;
-        self.expect(&token::Colon)?;
-        let ty = self.parse_ty()?;
-        let hi = self.token.span;
-        self.expect_semi()?;
-        Ok(ForeignItem {
-            ident,
-            attrs,
-            kind: ForeignItemKind::Static(ty, mutbl),
-            id: DUMMY_NODE_ID,
-            span: lo.to(hi),
-            vis,
-        })
-    }
-
-    /// Parses a type from a foreign module.
-    fn parse_item_foreign_type(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
-                             -> PResult<'a, ForeignItem> {
-        self.expect_keyword(kw::Type)?;
-
-        let ident = self.parse_ident()?;
-        let hi = self.token.span;
-        self.expect_semi()?;
-        Ok(ast::ForeignItem {
-            ident,
-            attrs,
-            kind: ForeignItemKind::Ty,
-            id: DUMMY_NODE_ID,
-            span: lo.to(hi),
-            vis
-        })
-    }
-
-    fn is_static_global(&mut self) -> bool {
-        if self.check_keyword(kw::Static) {
-            // Check if this could be a closure.
-            !self.look_ahead(1, |token| {
-                if token.is_keyword(kw::Move) {
-                    return true;
-                }
-                match token.kind {
-                    token::BinOp(token::Or) | token::OrOr => true,
-                    _ => false,
-                }
-            })
-        } else {
-            false
-        }
-    }
-
-    /// Parse `["const" | ("static" "mut"?)] $ident ":" $ty = $expr` with
-    /// `["const" | ("static" "mut"?)]` already parsed and stored in `m`.
-    ///
-    /// When `m` is `"const"`, `$ident` may also be `"_"`.
-    fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<'a, ItemInfo> {
-        let id = if m.is_none() { self.parse_ident_or_underscore() } else { self.parse_ident() }?;
-
-        // Parse the type of a `const` or `static mut?` item.
-        // That is, the `":" $ty` fragment.
-        let ty = if self.token == token::Eq {
-            self.recover_missing_const_type(id, m)
-        } else {
-            // Not `=` so expect `":"" $ty` as usual.
-            self.expect(&token::Colon)?;
-            self.parse_ty()?
-        };
-
-        self.expect(&token::Eq)?;
-        let e = self.parse_expr()?;
-        self.expect_semi()?;
-        let item = match m {
-            Some(m) => ItemKind::Static(ty, m, e),
-            None => ItemKind::Const(ty, e),
-        };
-        Ok((id, item, None))
-    }
-
-    /// We were supposed to parse `:` but instead, we're already at `=`.
-    /// This means that the type is missing.
-    fn recover_missing_const_type(&mut self, id: Ident, m: Option<Mutability>) -> P<Ty> {
-        // Construct the error and stash it away with the hope
-        // that typeck will later enrich the error with a type.
-        let kind = match m {
-            Some(Mutability::Mutable) => "static mut",
-            Some(Mutability::Immutable) => "static",
-            None => "const",
-        };
-        let mut err = self.struct_span_err(id.span, &format!("missing type for `{}` item", kind));
-        err.span_suggestion(
-            id.span,
-            "provide a type for the item",
-            format!("{}: <type>", id),
-            Applicability::HasPlaceholders,
-        );
-        err.stash(id.span, StashKey::ItemNoType);
-
-        // The user intended that the type be inferred,
-        // so treat this as if the user wrote e.g. `const A: _ = expr;`.
-        P(Ty {
-            kind: TyKind::Infer,
-            span: id.span,
-            id: ast::DUMMY_NODE_ID,
-        })
-    }
-
-    /// Parses `type Foo = Bar;` or returns `None`
-    /// without modifying the parser state.
-    fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, Generics)>> {
-        // This parses the grammar:
-        //     Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
-        if self.eat_keyword(kw::Type) {
-            Some(self.parse_type_alias())
-        } else {
-            None
-        }
-    }
-
-    /// Parses a type alias or opaque type.
-    fn parse_type_alias(&mut self) -> PResult<'a, (Ident, AliasKind, Generics)> {
-        let ident = self.parse_ident()?;
-        let mut tps = self.parse_generics()?;
-        tps.where_clause = self.parse_where_clause()?;
-        self.expect(&token::Eq)?;
-        let alias = if self.check_keyword(kw::Impl) {
-            self.bump();
-            let bounds = self.parse_generic_bounds(Some(self.prev_span))?;
-            AliasKind::OpaqueTy(bounds)
-        } else {
-            let ty = self.parse_ty()?;
-            AliasKind::Weak(ty)
-        };
-        self.expect_semi()?;
-        Ok((ident, alias, tps))
-    }
-
-    /// Parses an enum declaration.
-    fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
-        let id = self.parse_ident()?;
-        let mut generics = self.parse_generics()?;
-        generics.where_clause = self.parse_where_clause()?;
-        self.expect(&token::OpenDelim(token::Brace))?;
-
-        let enum_definition = self.parse_enum_def(&generics).map_err(|e| {
-            self.recover_stmt();
-            self.eat(&token::CloseDelim(token::Brace));
-            e
-        })?;
-        Ok((id, ItemKind::Enum(enum_definition, generics), None))
-    }
-
-    /// Parses the part of an enum declaration following the `{`.
-    fn parse_enum_def(&mut self, _generics: &Generics) -> PResult<'a, EnumDef> {
-        let mut variants = Vec::new();
-        while self.token != token::CloseDelim(token::Brace) {
-            let variant_attrs = self.parse_outer_attributes()?;
-            let vlo = self.token.span;
-
-            self.eat_bad_pub();
-            let ident = self.parse_ident()?;
-
-            let struct_def = if self.check(&token::OpenDelim(token::Brace)) {
-                // Parse a struct variant.
-                let (fields, recovered) = self.parse_record_struct_body()?;
-                VariantData::Struct(fields, recovered)
-            } else if self.check(&token::OpenDelim(token::Paren)) {
-                VariantData::Tuple(
-                    self.parse_tuple_struct_body()?,
-                    DUMMY_NODE_ID,
-                )
-            } else {
-                VariantData::Unit(DUMMY_NODE_ID)
-            };
-
-            let disr_expr = if self.eat(&token::Eq) {
-                Some(AnonConst {
-                    id: DUMMY_NODE_ID,
-                    value: self.parse_expr()?,
-                })
-            } else {
-                None
-            };
-
-            let vr = ast::Variant {
-                ident,
-                id: DUMMY_NODE_ID,
-                attrs: variant_attrs,
-                data: struct_def,
-                disr_expr,
-                span: vlo.to(self.prev_span),
-                is_placeholder: false,
-            };
-            variants.push(vr);
-
-            if !self.eat(&token::Comma) {
-                if self.token.is_ident() && !self.token.is_reserved_ident() {
-                    let sp = self.sess.source_map().next_point(self.prev_span);
-                    self.struct_span_err(sp, "missing comma")
-                        .span_suggestion_short(
-                            sp,
-                            "missing comma",
-                            ",".to_owned(),
-                            Applicability::MaybeIncorrect,
-                        )
-                        .emit();
-                } else {
-                    break;
-                }
-            }
-        }
-        self.expect(&token::CloseDelim(token::Brace))?;
-
-        Ok(ast::EnumDef { variants })
-    }
-
-    /// Parses `struct Foo { ... }`.
-    fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
-        let class_name = self.parse_ident()?;
-
-        let mut generics = self.parse_generics()?;
-
-        // There is a special case worth noting here, as reported in issue #17904.
-        // If we are parsing a tuple struct it is the case that the where clause
-        // should follow the field list. Like so:
-        //
-        // struct Foo<T>(T) where T: Copy;
-        //
-        // If we are parsing a normal record-style struct it is the case
-        // that the where clause comes before the body, and after the generics.
-        // So if we look ahead and see a brace or a where-clause we begin
-        // parsing a record style struct.
-        //
-        // Otherwise if we look ahead and see a paren we parse a tuple-style
-        // struct.
-
-        let vdata = if self.token.is_keyword(kw::Where) {
-            generics.where_clause = self.parse_where_clause()?;
-            if self.eat(&token::Semi) {
-                // If we see a: `struct Foo<T> where T: Copy;` style decl.
-                VariantData::Unit(DUMMY_NODE_ID)
-            } else {
-                // If we see: `struct Foo<T> where T: Copy { ... }`
-                let (fields, recovered) = self.parse_record_struct_body()?;
-                VariantData::Struct(fields, recovered)
-            }
-        // No `where` so: `struct Foo<T>;`
-        } else if self.eat(&token::Semi) {
-            VariantData::Unit(DUMMY_NODE_ID)
-        // Record-style struct definition
-        } else if self.token == token::OpenDelim(token::Brace) {
-            let (fields, recovered) = self.parse_record_struct_body()?;
-            VariantData::Struct(fields, recovered)
-        // Tuple-style struct definition with optional where-clause.
-        } else if self.token == token::OpenDelim(token::Paren) {
-            let body = VariantData::Tuple(self.parse_tuple_struct_body()?, DUMMY_NODE_ID);
-            generics.where_clause = self.parse_where_clause()?;
-            self.expect_semi()?;
-            body
-        } else {
-            let token_str = self.this_token_descr();
-            let mut err = self.fatal(&format!(
-                "expected `where`, `{{`, `(`, or `;` after struct name, found {}",
-                token_str
-            ));
-            err.span_label(self.token.span, "expected `where`, `{`, `(`, or `;` after struct name");
-            return Err(err);
-        };
-
-        Ok((class_name, ItemKind::Struct(vdata, generics), None))
-    }
-
-    /// Parses `union Foo { ... }`.
-    fn parse_item_union(&mut self) -> PResult<'a, ItemInfo> {
-        let class_name = self.parse_ident()?;
-
-        let mut generics = self.parse_generics()?;
-
-        let vdata = if self.token.is_keyword(kw::Where) {
-            generics.where_clause = self.parse_where_clause()?;
-            let (fields, recovered) = self.parse_record_struct_body()?;
-            VariantData::Struct(fields, recovered)
-        } else if self.token == token::OpenDelim(token::Brace) {
-            let (fields, recovered) = self.parse_record_struct_body()?;
-            VariantData::Struct(fields, recovered)
-        } else {
-            let token_str = self.this_token_descr();
-            let mut err = self.fatal(&format!(
-                "expected `where` or `{{` after union name, found {}", token_str));
-            err.span_label(self.token.span, "expected `where` or `{` after union name");
-            return Err(err);
-        };
-
-        Ok((class_name, ItemKind::Union(vdata, generics), None))
-    }
-
-    pub(super) fn is_union_item(&self) -> bool {
-        self.token.is_keyword(kw::Union) &&
-        self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
-    }
-
-    fn parse_record_struct_body(
-        &mut self,
-    ) -> PResult<'a, (Vec<StructField>, /* recovered */ bool)> {
-        let mut fields = Vec::new();
-        let mut recovered = false;
-        if self.eat(&token::OpenDelim(token::Brace)) {
-            while self.token != token::CloseDelim(token::Brace) {
-                let field = self.parse_struct_decl_field().map_err(|e| {
-                    self.consume_block(token::Brace, ConsumeClosingDelim::No);
-                    recovered = true;
-                    e
-                });
-                match field {
-                    Ok(field) => fields.push(field),
-                    Err(mut err) => {
-                        err.emit();
-                        break;
-                    }
-                }
-            }
-            self.eat(&token::CloseDelim(token::Brace));
-        } else {
-            let token_str = self.this_token_descr();
-            let mut err = self.fatal(&format!(
-                    "expected `where`, or `{{` after struct name, found {}", token_str));
-            err.span_label(self.token.span, "expected `where`, or `{` after struct name");
-            return Err(err);
-        }
-
-        Ok((fields, recovered))
-    }
-
-    fn parse_tuple_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
-        // This is the case where we find `struct Foo<T>(T) where T: Copy;`
-        // Unit like structs are handled in parse_item_struct function
-        self.parse_paren_comma_seq(|p| {
-            let attrs = p.parse_outer_attributes()?;
-            let lo = p.token.span;
-            let vis = p.parse_visibility(true)?;
-            let ty = p.parse_ty()?;
-            Ok(StructField {
-                span: lo.to(ty.span),
-                vis,
-                ident: None,
-                id: DUMMY_NODE_ID,
-                ty,
-                attrs,
-                is_placeholder: false,
-            })
-        }).map(|(r, _)| r)
-    }
-
-    /// Parses an element of a struct declaration.
-    fn parse_struct_decl_field(&mut self) -> PResult<'a, StructField> {
-        let attrs = self.parse_outer_attributes()?;
-        let lo = self.token.span;
-        let vis = self.parse_visibility(false)?;
-        self.parse_single_struct_field(lo, vis, attrs)
-    }
-
-    /// Parses a structure field declaration.
-    fn parse_single_struct_field(&mut self,
-                                     lo: Span,
-                                     vis: Visibility,
-                                     attrs: Vec<Attribute> )
-                                     -> PResult<'a, StructField> {
-        let mut seen_comma: bool = false;
-        let a_var = self.parse_name_and_ty(lo, vis, attrs)?;
-        if self.token == token::Comma {
-            seen_comma = true;
-        }
-        match self.token.kind {
-            token::Comma => {
-                self.bump();
-            }
-            token::CloseDelim(token::Brace) => {}
-            token::DocComment(_) => {
-                let previous_span = self.prev_span;
-                let mut err = self.span_fatal_err(self.token.span, Error::UselessDocComment);
-                self.bump(); // consume the doc comment
-                let comma_after_doc_seen = self.eat(&token::Comma);
-                // `seen_comma` is always false, because we are inside doc block
-                // condition is here to make code more readable
-                if seen_comma == false && comma_after_doc_seen == true {
-                    seen_comma = true;
-                }
-                if comma_after_doc_seen || self.token == token::CloseDelim(token::Brace) {
-                    err.emit();
-                } else {
-                    if seen_comma == false {
-                        let sp = self.sess.source_map().next_point(previous_span);
-                        err.span_suggestion(
-                            sp,
-                            "missing comma here",
-                            ",".into(),
-                            Applicability::MachineApplicable
-                        );
-                    }
-                    return Err(err);
-                }
-            }
-            _ => {
-                let sp = self.sess.source_map().next_point(self.prev_span);
-                let mut err = self.struct_span_err(sp, &format!("expected `,`, or `}}`, found {}",
-                                                                self.this_token_descr()));
-                if self.token.is_ident() {
-                    // This is likely another field; emit the diagnostic and keep going
-                    err.span_suggestion(
-                        sp,
-                        "try adding a comma",
-                        ",".into(),
-                        Applicability::MachineApplicable,
-                    );
-                    err.emit();
-                } else {
-                    return Err(err)
-                }
-            }
-        }
-        Ok(a_var)
-    }
-
-    /// Parses a structure field.
-    fn parse_name_and_ty(
-        &mut self,
-        lo: Span,
-        vis: Visibility,
-        attrs: Vec<Attribute>
-    ) -> PResult<'a, StructField> {
-        let name = self.parse_ident()?;
-        self.expect(&token::Colon)?;
-        let ty = self.parse_ty()?;
-        Ok(StructField {
-            span: lo.to(self.prev_span),
-            ident: Some(name),
-            vis,
-            id: DUMMY_NODE_ID,
-            ty,
-            attrs,
-            is_placeholder: false,
-        })
-    }
-
-    pub(super) fn eat_macro_def(
-        &mut self,
-        attrs: &[Attribute],
-        vis: &Visibility,
-        lo: Span
-    ) -> PResult<'a, Option<P<Item>>> {
-        let token_lo = self.token.span;
-        let (ident, def) = if self.eat_keyword(kw::Macro) {
-            let ident = self.parse_ident()?;
-            let tokens = if self.check(&token::OpenDelim(token::Brace)) {
-                match self.parse_token_tree() {
-                    TokenTree::Delimited(_, _, tts) => tts,
-                    _ => unreachable!(),
-                }
-            } else if self.check(&token::OpenDelim(token::Paren)) {
-                let args = self.parse_token_tree();
-                let body = if self.check(&token::OpenDelim(token::Brace)) {
-                    self.parse_token_tree()
-                } else {
-                    self.unexpected()?;
-                    unreachable!()
-                };
-                TokenStream::new(vec![
-                    args.into(),
-                    TokenTree::token(token::FatArrow, token_lo.to(self.prev_span)).into(),
-                    body.into(),
-                ])
-            } else {
-                self.unexpected()?;
-                unreachable!()
-            };
-
-            (ident, ast::MacroDef { tokens: tokens.into(), legacy: false })
-        } else if self.check_keyword(sym::macro_rules) &&
-                  self.look_ahead(1, |t| *t == token::Not) &&
-                  self.look_ahead(2, |t| t.is_ident()) {
-            let prev_span = self.prev_span;
-            self.complain_if_pub_macro(&vis.node, prev_span);
-            self.bump();
-            self.bump();
-
-            let ident = self.parse_ident()?;
-            let (delim, tokens) = self.expect_delimited_token_tree()?;
-            if delim != MacDelimiter::Brace && !self.eat(&token::Semi) {
-                self.report_invalid_macro_expansion_item();
-            }
-
-            (ident, ast::MacroDef { tokens, legacy: true })
-        } else {
-            return Ok(None);
-        };
-
-        let span = lo.to(self.prev_span);
-
-        if !def.legacy {
-            self.sess.gated_spans.gate(sym::decl_macro, span);
-        }
-
-        Ok(Some(self.mk_item(span, ident, ItemKind::MacroDef(def), vis.clone(), attrs.to_vec())))
-    }
-
-    fn complain_if_pub_macro(&self, vis: &VisibilityKind, sp: Span) {
-        match *vis {
-            VisibilityKind::Inherited => {}
-            _ => {
-                let mut err = if self.token.is_keyword(sym::macro_rules) {
-                    let mut err = self.diagnostic()
-                        .struct_span_err(sp, "can't qualify macro_rules invocation with `pub`");
-                    err.span_suggestion(
-                        sp,
-                        "try exporting the macro",
-                        "#[macro_export]".to_owned(),
-                        Applicability::MaybeIncorrect // speculative
-                    );
-                    err
-                } else {
-                    let mut err = self.diagnostic()
-                        .struct_span_err(sp, "can't qualify macro invocation with `pub`");
-                    err.help("try adjusting the macro to put `pub` inside the invocation");
-                    err
-                };
-                err.emit();
-            }
-        }
-    }
-
-    fn report_invalid_macro_expansion_item(&self) {
-        self.struct_span_err(
-            self.prev_span,
-            "macros that expand to items must be delimited with braces or followed by a semicolon",
-        ).multipart_suggestion(
-            "change the delimiters to curly braces",
-            vec![
-                (self.prev_span.with_hi(self.prev_span.lo() + BytePos(1)), String::from(" {")),
-                (self.prev_span.with_lo(self.prev_span.hi() - BytePos(1)), '}'.to_string()),
-            ],
-            Applicability::MaybeIncorrect,
-        ).span_suggestion(
-            self.sess.source_map().next_point(self.prev_span),
-            "add a semicolon",
-            ';'.to_string(),
-            Applicability::MaybeIncorrect,
-        ).emit();
-    }
-
-    fn mk_item(&self, span: Span, ident: Ident, kind: ItemKind, vis: Visibility,
-               attrs: Vec<Attribute>) -> P<Item> {
-        P(Item {
-            ident,
-            attrs,
-            id: DUMMY_NODE_ID,
-            kind,
-            vis,
-            span,
-            tokens: None,
-        })
-    }
-}
-
-/// The parsing configuration used to parse a parameter list (see `parse_fn_params`).
-pub(super) struct ParamCfg {
-    /// Is `self` is allowed as the first parameter?
-    pub is_self_allowed: bool,
-    /// Is `...` allowed as the tail of the parameter list?
-    pub allow_c_variadic: bool,
-    /// `is_name_required` decides if, per-parameter,
-    /// the parameter must have a pattern or just a type.
-    pub is_name_required: fn(&token::Token) -> bool,
-}
-
-/// Parsing of functions and methods.
-impl<'a> Parser<'a> {
-    /// Parses an item-position function declaration.
-    fn parse_item_fn(
-        &mut self,
-        lo: Span,
-        vis: Visibility,
-        attrs: Vec<Attribute>,
-        header: FnHeader,
-    ) -> PResult<'a, Option<P<Item>>> {
-        let (ident, decl, generics) = self.parse_fn_sig(ParamCfg {
-            is_self_allowed: false,
-            allow_c_variadic: header.abi.symbol == sym::C && header.unsafety == Unsafety::Unsafe,
-            is_name_required: |_| true,
-        })?;
-        let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
-        let kind = ItemKind::Fn(FnSig { decl, header }, generics, body);
-        self.mk_item_with_info(attrs, lo, vis, (ident, kind, Some(inner_attrs)))
-    }
-
-    /// Parses a function declaration from a foreign module.
-    fn parse_item_foreign_fn(
-        &mut self,
-        vis: ast::Visibility,
-        lo: Span,
-        attrs: Vec<Attribute>,
-        extern_sp: Span,
-    ) -> PResult<'a, ForeignItem> {
-        self.expect_keyword(kw::Fn)?;
-        let (ident, decl, generics) = self.parse_fn_sig(ParamCfg {
-            is_self_allowed: false,
-            allow_c_variadic: true,
-            is_name_required: |_| true,
-        })?;
-        let span = lo.to(self.token.span);
-        self.parse_semi_or_incorrect_foreign_fn_body(&ident, extern_sp)?;
-        Ok(ast::ForeignItem {
-            ident,
-            attrs,
-            kind: ForeignItemKind::Fn(decl, generics),
-            id: DUMMY_NODE_ID,
-            span,
-            vis,
-        })
-    }
-
-    /// Parses a method or a macro invocation in a trait impl.
-    fn parse_impl_method(
-        &mut self,
-        at_end: &mut bool,
-    ) -> PResult<'a, (Ident, Vec<Attribute>, Generics, ImplItemKind)> {
-        let (ident, sig, generics) = self.parse_method_sig(|_| true)?;
-        *at_end = true;
-        let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
-        Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(sig, body)))
-    }
-
-    fn parse_trait_item_method(
-        &mut self,
-        at_end: &mut bool,
-        attrs: &mut Vec<Attribute>,
-    ) -> PResult<'a, (Ident, TraitItemKind, Generics)> {
-        // This is somewhat dubious; We don't want to allow
-        // argument names to be left off if there is a definition...
-        //
-        // We don't allow argument names to be left off in edition 2018.
-        let (ident, sig, generics) = self.parse_method_sig(|t| t.span.rust_2018())?;
-        let body = self.parse_trait_method_body(at_end, attrs)?;
-        Ok((ident, TraitItemKind::Method(sig, body), generics))
-    }
-
-    /// Parse the "body" of a method in a trait item definition.
-    /// This can either be `;` when there's no body,
-    /// or e.g. a block when the method is a provided one.
-    fn parse_trait_method_body(
-        &mut self,
-        at_end: &mut bool,
-        attrs: &mut Vec<Attribute>,
-    ) -> PResult<'a, Option<P<Block>>> {
-        Ok(match self.token.kind {
-            token::Semi => {
-                debug!("parse_trait_method_body(): parsing required method");
-                self.bump();
-                *at_end = true;
-                None
-            }
-            token::OpenDelim(token::Brace) => {
-                debug!("parse_trait_method_body(): parsing provided method");
-                *at_end = true;
-                let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
-                attrs.extend(inner_attrs.iter().cloned());
-                Some(body)
-            }
-            token::Interpolated(ref nt) => {
-                match **nt {
-                    token::NtBlock(..) => {
-                        *at_end = true;
-                        let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
-                        attrs.extend(inner_attrs.iter().cloned());
-                        Some(body)
-                    }
-                    _ => return self.expected_semi_or_open_brace(),
-                }
-            }
-            _ => return self.expected_semi_or_open_brace(),
-        })
-    }
-
-    /// Parse the "signature", including the identifier, parameters, and generics
-    /// of a method. The body is not parsed as that differs between `trait`s and `impl`s.
-    fn parse_method_sig(
-        &mut self,
-        is_name_required: fn(&token::Token) -> bool,
-    ) -> PResult<'a, (Ident, FnSig, Generics)> {
-        let header = self.parse_fn_front_matter()?;
-        let (ident, decl, generics) = self.parse_fn_sig(ParamCfg {
-            is_self_allowed: true,
-            allow_c_variadic: false,
-            is_name_required,
-        })?;
-        Ok((ident, FnSig { header, decl }, generics))
-    }
-
-    /// Parses all the "front matter" for a `fn` declaration, up to
-    /// and including the `fn` keyword:
-    ///
-    /// - `const fn`
-    /// - `unsafe fn`
-    /// - `const unsafe fn`
-    /// - `extern fn`
-    /// - etc.
-    fn parse_fn_front_matter(&mut self) -> PResult<'a, FnHeader> {
-        let is_const_fn = self.eat_keyword(kw::Const);
-        let const_span = self.prev_span;
-        let asyncness = self.parse_asyncness();
-        if let IsAsync::Async { .. } = asyncness {
-            self.ban_async_in_2015(self.prev_span);
-        }
-        let asyncness = respan(self.prev_span, asyncness);
-        let unsafety = self.parse_unsafety();
-        let (constness, unsafety, abi) = if is_const_fn {
-            (respan(const_span, Constness::Const), unsafety, Abi::default())
-        } else {
-            let abi = self.parse_extern_abi()?;
-            (respan(self.prev_span, Constness::NotConst), unsafety, abi)
-        };
-        if !self.eat_keyword(kw::Fn) {
-            // It is possible for `expect_one_of` to recover given the contents of
-            // `self.expected_tokens`, therefore, do not use `self.unexpected()` which doesn't
-            // account for this.
-            if !self.expect_one_of(&[], &[])? { unreachable!() }
-        }
-        Ok(FnHeader { constness, unsafety, asyncness, abi })
-    }
-
-    /// Parse the "signature", including the identifier, parameters, and generics of a function.
-    fn parse_fn_sig(&mut self, cfg: ParamCfg) -> PResult<'a, (Ident, P<FnDecl>, Generics)> {
-        let ident = self.parse_ident()?;
-        let mut generics = self.parse_generics()?;
-        let decl = self.parse_fn_decl(cfg, true)?;
-        generics.where_clause = self.parse_where_clause()?;
-        Ok((ident, decl, generics))
-    }
-
-    /// Parses the parameter list and result type of a function declaration.
-    pub(super) fn parse_fn_decl(
-        &mut self,
-        cfg: ParamCfg,
-        ret_allow_plus: bool,
-    ) -> PResult<'a, P<FnDecl>> {
-        Ok(P(FnDecl {
-            inputs: self.parse_fn_params(cfg)?,
-            output: self.parse_ret_ty(ret_allow_plus)?,
-        }))
-    }
-
-    /// Parses the parameter list of a function, including the `(` and `)` delimiters.
-    fn parse_fn_params(&mut self, mut cfg: ParamCfg) -> PResult<'a, Vec<Param>> {
-        let sp = self.token.span;
-        let is_trait_item = cfg.is_self_allowed;
-        let mut c_variadic = false;
-        // Parse the arguments, starting out with `self` being possibly allowed...
-        let (params, _) = self.parse_paren_comma_seq(|p| {
-            let param = p.parse_param_general(&cfg, is_trait_item);
-            // ...now that we've parsed the first argument, `self` is no longer allowed.
-            cfg.is_self_allowed = false;
-
-            match param {
-                Ok(param) => Ok(
-                    if let TyKind::CVarArgs = param.ty.kind {
-                        c_variadic = true;
-                        if p.token != token::CloseDelim(token::Paren) {
-                            p.span_err(
-                                p.token.span,
-                                "`...` must be the last argument of a C-variadic function",
-                            );
-                            // FIXME(eddyb) this should probably still push `CVarArgs`.
-                            // Maybe AST validation/HIR lowering should emit the above error?
-                            None
-                        } else {
-                            Some(param)
-                        }
-                    } else {
-                        Some(param)
-                    }
-                ),
-                Err(mut e) => {
-                    e.emit();
-                    let lo = p.prev_span;
-                    // Skip every token until next possible arg or end.
-                    p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]);
-                    // Create a placeholder argument for proper arg count (issue #34264).
-                    let span = lo.to(p.prev_span);
-                    Ok(Some(dummy_arg(Ident::new(kw::Invalid, span))))
-                }
-            }
-        })?;
-
-        let mut params: Vec<_> = params.into_iter().filter_map(|x| x).collect();
-
-        // Replace duplicated recovered params with `_` pattern to avoid unecessary errors.
-        self.deduplicate_recovered_params_names(&mut params);
-
-        if c_variadic && params.len() <= 1 {
-            self.span_err(
-                sp,
-                "C-variadic function must be declared with at least one named argument",
-            );
-        }
-
-        Ok(params)
-    }
-
-    /// Skips unexpected attributes and doc comments in this position and emits an appropriate
-    /// error.
-    /// This version of parse param doesn't necessarily require identifier names.
-    fn parse_param_general(&mut self, cfg: &ParamCfg, is_trait_item: bool) -> PResult<'a, Param> {
-        let lo = self.token.span;
-        let attrs = self.parse_outer_attributes()?;
-
-        // Possibly parse `self`. Recover if we parsed it and it wasn't allowed here.
-        if let Some(mut param) = self.parse_self_param()? {
-            param.attrs = attrs.into();
-            return if cfg.is_self_allowed {
-                Ok(param)
-            } else {
-                self.recover_bad_self_param(param, is_trait_item)
-            };
-        }
-
-        let is_name_required = match self.token.kind {
-            token::DotDotDot => false,
-            _ => (cfg.is_name_required)(&self.token),
-        };
-        let (pat, ty) = if is_name_required || self.is_named_param() {
-            debug!("parse_param_general parse_pat (is_name_required:{})", is_name_required);
-
-            let pat = self.parse_fn_param_pat()?;
-            if let Err(mut err) = self.expect(&token::Colon) {
-                return if let Some(ident) = self.parameter_without_type(
-                    &mut err,
-                    pat,
-                    is_name_required,
-                    cfg.is_self_allowed,
-                    is_trait_item,
-                ) {
-                    err.emit();
-                    Ok(dummy_arg(ident))
-                } else {
-                    Err(err)
-                };
-            }
-
-            self.eat_incorrect_doc_comment_for_param_type();
-            (pat, self.parse_ty_common(true, true, cfg.allow_c_variadic)?)
-        } else {
-            debug!("parse_param_general ident_to_pat");
-            let parser_snapshot_before_ty = self.clone();
-            self.eat_incorrect_doc_comment_for_param_type();
-            let mut ty = self.parse_ty_common(true, true, cfg.allow_c_variadic);
-            if ty.is_ok() && self.token != token::Comma &&
-               self.token != token::CloseDelim(token::Paren) {
-                // This wasn't actually a type, but a pattern looking like a type,
-                // so we are going to rollback and re-parse for recovery.
-                ty = self.unexpected();
-            }
-            match ty {
-                Ok(ty) => {
-                    let ident = Ident::new(kw::Invalid, self.prev_span);
-                    let bm = BindingMode::ByValue(Mutability::Immutable);
-                    let pat = self.mk_pat_ident(ty.span, bm, ident);
-                    (pat, ty)
-                }
-                // If this is a C-variadic argument and we hit an error, return the error.
-                Err(err) if self.token == token::DotDotDot => return Err(err),
-                // Recover from attempting to parse the argument as a type without pattern.
-                Err(mut err) => {
-                    err.cancel();
-                    mem::replace(self, parser_snapshot_before_ty);
-                    self.recover_arg_parse()?
-                }
-            }
-        };
-
-        let span = lo.to(self.token.span);
-
-        Ok(Param {
-            attrs: attrs.into(),
-            id: ast::DUMMY_NODE_ID,
-            is_placeholder: false,
-            pat,
-            span,
-            ty,
-        })
-    }
-
-    /// Returns the parsed optional self parameter and whether a self shortcut was used.
-    ///
-    /// See `parse_self_param_with_attrs` to collect attributes.
-    fn parse_self_param(&mut self) -> PResult<'a, Option<Param>> {
-        // Extract an identifier *after* having confirmed that the token is one.
-        let expect_self_ident = |this: &mut Self| {
-            match this.token.kind {
-                // Preserve hygienic context.
-                token::Ident(name, _) => {
-                    let span = this.token.span;
-                    this.bump();
-                    Ident::new(name, span)
-                }
-                _ => unreachable!(),
-            }
-        };
-        // Is `self` `n` tokens ahead?
-        let is_isolated_self = |this: &Self, n| {
-            this.is_keyword_ahead(n, &[kw::SelfLower])
-            && this.look_ahead(n + 1, |t| t != &token::ModSep)
-        };
-        // Is `mut self` `n` tokens ahead?
-        let is_isolated_mut_self = |this: &Self, n| {
-            this.is_keyword_ahead(n, &[kw::Mut])
-            && is_isolated_self(this, n + 1)
-        };
-        // Parse `self` or `self: TYPE`. We already know the current token is `self`.
-        let parse_self_possibly_typed = |this: &mut Self, m| {
-            let eself_ident = expect_self_ident(this);
-            let eself_hi = this.prev_span;
-            let eself = if this.eat(&token::Colon) {
-                SelfKind::Explicit(this.parse_ty()?, m)
-            } else {
-                SelfKind::Value(m)
-            };
-            Ok((eself, eself_ident, eself_hi))
-        };
-        // Recover for the grammar `*self`, `*const self`, and `*mut self`.
-        let recover_self_ptr = |this: &mut Self| {
-            let msg = "cannot pass `self` by raw pointer";
-            let span = this.token.span;
-            this.struct_span_err(span, msg)
-                .span_label(span, msg)
-                .emit();
-
-            Ok((SelfKind::Value(Mutability::Immutable), expect_self_ident(this), this.prev_span))
-        };
-
-        // Parse optional `self` parameter of a method.
-        // Only a limited set of initial token sequences is considered `self` parameters; anything
-        // else is parsed as a normal function parameter list, so some lookahead is required.
-        let eself_lo = self.token.span;
-        let (eself, eself_ident, eself_hi) = match self.token.kind {
-            token::BinOp(token::And) => {
-                let eself = if is_isolated_self(self, 1) {
-                    // `&self`
-                    self.bump();
-                    SelfKind::Region(None, Mutability::Immutable)
-                } else if is_isolated_mut_self(self, 1) {
-                    // `&mut self`
-                    self.bump();
-                    self.bump();
-                    SelfKind::Region(None, Mutability::Mutable)
-                } else if self.look_ahead(1, |t| t.is_lifetime()) && is_isolated_self(self, 2) {
-                    // `&'lt self`
-                    self.bump();
-                    let lt = self.expect_lifetime();
-                    SelfKind::Region(Some(lt), Mutability::Immutable)
-                } else if self.look_ahead(1, |t| t.is_lifetime()) && is_isolated_mut_self(self, 2) {
-                    // `&'lt mut self`
-                    self.bump();
-                    let lt = self.expect_lifetime();
-                    self.bump();
-                    SelfKind::Region(Some(lt), Mutability::Mutable)
-                } else {
-                    // `&not_self`
-                    return Ok(None);
-                };
-                (eself, expect_self_ident(self), self.prev_span)
-            }
-            // `*self`
-            token::BinOp(token::Star) if is_isolated_self(self, 1) => {
-                self.bump();
-                recover_self_ptr(self)?
-            }
-            // `*mut self` and `*const self`
-            token::BinOp(token::Star) if
-                self.look_ahead(1, |t| t.is_mutability())
-                && is_isolated_self(self, 2) =>
-            {
-                self.bump();
-                self.bump();
-                recover_self_ptr(self)?
-            }
-            // `self` and `self: TYPE`
-            token::Ident(..) if is_isolated_self(self, 0) => {
-                parse_self_possibly_typed(self, Mutability::Immutable)?
-            }
-            // `mut self` and `mut self: TYPE`
-            token::Ident(..) if is_isolated_mut_self(self, 0) => {
-                self.bump();
-                parse_self_possibly_typed(self, Mutability::Mutable)?
-            }
-            _ => return Ok(None),
-        };
-
-        let eself = source_map::respan(eself_lo.to(eself_hi), eself);
-        Ok(Some(Param::from_self(ThinVec::default(), eself, eself_ident)))
-    }
-
-    fn is_named_param(&self) -> bool {
-        let offset = match self.token.kind {
-            token::Interpolated(ref nt) => match **nt {
-                token::NtPat(..) => return self.look_ahead(1, |t| t == &token::Colon),
-                _ => 0,
-            }
-            token::BinOp(token::And) | token::AndAnd => 1,
-            _ if self.token.is_keyword(kw::Mut) => 1,
-            _ => 0,
-        };
-
-        self.look_ahead(offset, |t| t.is_ident()) &&
-        self.look_ahead(offset + 1, |t| t == &token::Colon)
-    }
-
-    fn recover_first_param(&mut self) -> &'static str {
-        match self.parse_outer_attributes()
-            .and_then(|_| self.parse_self_param())
-            .map_err(|mut e| e.cancel())
-        {
-            Ok(Some(_)) => "method",
-            _ => "function",
-        }
-    }
-}
diff --git a/src/libsyntax/parse/parser/mod.rs b/src/libsyntax/parse/parser/mod.rs
deleted file mode 100644
index 455f4172f5f..00000000000
--- a/src/libsyntax/parse/parser/mod.rs
+++ /dev/null
@@ -1,1391 +0,0 @@
-pub mod attr;
-mod expr;
-mod pat;
-mod item;
-mod module;
-mod ty;
-mod path;
-pub use path::PathStyle;
-mod stmt;
-mod generics;
-mod diagnostics;
-use diagnostics::Error;
-
-use crate::ast::{
-    self, Abi, DUMMY_NODE_ID, AttrStyle, Attribute, CrateSugar, Ident,
-    IsAsync, MacDelimiter, Mutability, StrStyle, Visibility, VisibilityKind, Unsafety,
-};
-use crate::parse::{Directory, DirectoryOwnership};
-use crate::parse::lexer::UnmatchedBrace;
-use crate::util::comments::{doc_comment_style, strip_doc_comment_decoration};
-use crate::token::{self, Token, TokenKind, DelimToken};
-use crate::print::pprust;
-use crate::ptr::P;
-use crate::sess::ParseSess;
-use crate::source_map::respan;
-use crate::symbol::{kw, sym, Symbol};
-use crate::tokenstream::{self, DelimSpan, TokenTree, TokenStream, TreeAndJoint};
-use crate::ThinVec;
-
-use errors::{PResult, Applicability, DiagnosticBuilder, DiagnosticId, FatalError};
-use syntax_pos::{Span, BytePos, DUMMY_SP, FileName};
-use log::debug;
-
-use std::borrow::Cow;
-use std::{cmp, mem, slice};
-use std::path::PathBuf;
-
-bitflags::bitflags! {
-    struct Restrictions: u8 {
-        const STMT_EXPR         = 1 << 0;
-        const NO_STRUCT_LITERAL = 1 << 1;
-    }
-}
-
-#[derive(Clone, Copy, PartialEq, Debug)]
-enum SemiColonMode {
-    Break,
-    Ignore,
-    Comma,
-}
-
-#[derive(Clone, Copy, PartialEq, Debug)]
-enum BlockMode {
-    Break,
-    Ignore,
-}
-
-/// Like `maybe_whole_expr`, but for things other than expressions.
-#[macro_export]
-macro_rules! maybe_whole {
-    ($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
-        if let token::Interpolated(nt) = &$p.token.kind {
-            if let token::$constructor(x) = &**nt {
-                let $x = x.clone();
-                $p.bump();
-                return Ok($e);
-            }
-        }
-    };
-}
-
-/// If the next tokens are ill-formed `$ty::` recover them as `<$ty>::`.
-#[macro_export]
-macro_rules! maybe_recover_from_interpolated_ty_qpath {
-    ($self: expr, $allow_qpath_recovery: expr) => {
-        if $allow_qpath_recovery && $self.look_ahead(1, |t| t == &token::ModSep) {
-            if let token::Interpolated(nt) = &$self.token.kind {
-                if let token::NtTy(ty) = &**nt {
-                    let ty = ty.clone();
-                    $self.bump();
-                    return $self.maybe_recover_from_bad_qpath_stage_2($self.prev_span, ty);
-                }
-            }
-        }
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq)]
-enum PrevTokenKind {
-    DocComment,
-    Comma,
-    Plus,
-    Interpolated,
-    Eof,
-    Ident,
-    BitOr,
-    Other,
-}
-
-// NOTE: `Ident`s are handled by `common.rs`.
-
-#[derive(Clone)]
-pub struct Parser<'a> {
-    pub sess: &'a ParseSess,
-    /// The current normalized token.
-    /// "Normalized" means that some interpolated tokens
-    /// (`$i: ident` and `$l: lifetime` meta-variables) are replaced
-    /// with non-interpolated identifier and lifetime tokens they refer to.
-    /// Perhaps the normalized / non-normalized setup can be simplified somehow.
-    pub token: Token,
-    /// The span of the current non-normalized token.
-    meta_var_span: Option<Span>,
-    /// The span of the previous non-normalized token.
-    pub prev_span: Span,
-    /// The kind of the previous normalized token (in simplified form).
-    prev_token_kind: PrevTokenKind,
-    restrictions: Restrictions,
-    /// Used to determine the path to externally loaded source files.
-    pub(super) directory: Directory<'a>,
-    /// `true` to parse sub-modules in other files.
-    pub(super) recurse_into_file_modules: bool,
-    /// Name of the root module this parser originated from. If `None`, then the
-    /// name is not known. This does not change while the parser is descending
-    /// into modules, and sub-parsers have new values for this name.
-    pub root_module_name: Option<String>,
-    expected_tokens: Vec<TokenType>,
-    token_cursor: TokenCursor,
-    desugar_doc_comments: bool,
-    /// `true` we should configure out of line modules as we parse.
-    cfg_mods: bool,
-    /// This field is used to keep track of how many left angle brackets we have seen. This is
-    /// required in order to detect extra leading left angle brackets (`<` characters) and error
-    /// appropriately.
-    ///
-    /// See the comments in the `parse_path_segment` function for more details.
-    unmatched_angle_bracket_count: u32,
-    max_angle_bracket_count: u32,
-    /// A list of all unclosed delimiters found by the lexer. If an entry is used for error recovery
-    /// it gets removed from here. Every entry left at the end gets emitted as an independent
-    /// error.
-    pub(super) unclosed_delims: Vec<UnmatchedBrace>,
-    last_unexpected_token_span: Option<Span>,
-    pub last_type_ascription: Option<(Span, bool /* likely path typo */)>,
-    /// If present, this `Parser` is not parsing Rust code but rather a macro call.
-    subparser_name: Option<&'static str>,
-}
-
-impl<'a> Drop for Parser<'a> {
-    fn drop(&mut self) {
-        emit_unclosed_delims(&mut self.unclosed_delims, &self.sess);
-    }
-}
-
-#[derive(Clone)]
-struct TokenCursor {
-    frame: TokenCursorFrame,
-    stack: Vec<TokenCursorFrame>,
-}
-
-#[derive(Clone)]
-struct TokenCursorFrame {
-    delim: token::DelimToken,
-    span: DelimSpan,
-    open_delim: bool,
-    tree_cursor: tokenstream::Cursor,
-    close_delim: bool,
-    last_token: LastToken,
-}
-
-/// This is used in `TokenCursorFrame` above to track tokens that are consumed
-/// by the parser, and then that's transitively used to record the tokens that
-/// each parse AST item is created with.
-///
-/// Right now this has two states, either collecting tokens or not collecting
-/// tokens. If we're collecting tokens we just save everything off into a local
-/// `Vec`. This should eventually though likely save tokens from the original
-/// token stream and just use slicing of token streams to avoid creation of a
-/// whole new vector.
-///
-/// The second state is where we're passively not recording tokens, but the last
-/// token is still tracked for when we want to start recording tokens. This
-/// "last token" means that when we start recording tokens we'll want to ensure
-/// that this, the first token, is included in the output.
-///
-/// You can find some more example usage of this in the `collect_tokens` method
-/// on the parser.
-#[derive(Clone)]
-enum LastToken {
-    Collecting(Vec<TreeAndJoint>),
-    Was(Option<TreeAndJoint>),
-}
-
-impl TokenCursorFrame {
-    fn new(span: DelimSpan, delim: DelimToken, tts: &TokenStream) -> Self {
-        TokenCursorFrame {
-            delim,
-            span,
-            open_delim: delim == token::NoDelim,
-            tree_cursor: tts.clone().into_trees(),
-            close_delim: delim == token::NoDelim,
-            last_token: LastToken::Was(None),
-        }
-    }
-}
-
-impl TokenCursor {
-    fn next(&mut self) -> Token {
-        loop {
-            let tree = if !self.frame.open_delim {
-                self.frame.open_delim = true;
-                TokenTree::open_tt(self.frame.span, self.frame.delim)
-            } else if let Some(tree) = self.frame.tree_cursor.next() {
-                tree
-            } else if !self.frame.close_delim {
-                self.frame.close_delim = true;
-                TokenTree::close_tt(self.frame.span, self.frame.delim)
-            } else if let Some(frame) = self.stack.pop() {
-                self.frame = frame;
-                continue
-            } else {
-                return Token::new(token::Eof, DUMMY_SP);
-            };
-
-            match self.frame.last_token {
-                LastToken::Collecting(ref mut v) => v.push(tree.clone().into()),
-                LastToken::Was(ref mut t) => *t = Some(tree.clone().into()),
-            }
-
-            match tree {
-                TokenTree::Token(token) => return token,
-                TokenTree::Delimited(sp, delim, tts) => {
-                    let frame = TokenCursorFrame::new(sp, delim, &tts);
-                    self.stack.push(mem::replace(&mut self.frame, frame));
-                }
-            }
-        }
-    }
-
-    fn next_desugared(&mut self) -> Token {
-        let (name, sp) = match self.next() {
-            Token { kind: token::DocComment(name), span } => (name, span),
-            tok => return tok,
-        };
-
-        let stripped = strip_doc_comment_decoration(&name.as_str());
-
-        // Searches for the occurrences of `"#*` and returns the minimum number of `#`s
-        // required to wrap the text.
-        let mut num_of_hashes = 0;
-        let mut count = 0;
-        for ch in stripped.chars() {
-            count = match ch {
-                '"' => 1,
-                '#' if count > 0 => count + 1,
-                _ => 0,
-            };
-            num_of_hashes = cmp::max(num_of_hashes, count);
-        }
-
-        let delim_span = DelimSpan::from_single(sp);
-        let body = TokenTree::Delimited(
-            delim_span,
-            token::Bracket,
-            [
-                TokenTree::token(token::Ident(sym::doc, false), sp),
-                TokenTree::token(token::Eq, sp),
-                TokenTree::token(TokenKind::lit(
-                    token::StrRaw(num_of_hashes), Symbol::intern(&stripped), None
-                ), sp),
-            ]
-            .iter().cloned().collect::<TokenStream>().into(),
-        );
-
-        self.stack.push(mem::replace(&mut self.frame, TokenCursorFrame::new(
-            delim_span,
-            token::NoDelim,
-            &if doc_comment_style(&name.as_str()) == AttrStyle::Inner {
-                [TokenTree::token(token::Pound, sp), TokenTree::token(token::Not, sp), body]
-                    .iter().cloned().collect::<TokenStream>()
-            } else {
-                [TokenTree::token(token::Pound, sp), body]
-                    .iter().cloned().collect::<TokenStream>()
-            },
-        )));
-
-        self.next()
-    }
-}
-
-#[derive(Clone, PartialEq)]
-enum TokenType {
-    Token(TokenKind),
-    Keyword(Symbol),
-    Operator,
-    Lifetime,
-    Ident,
-    Path,
-    Type,
-    Const,
-}
-
-impl TokenType {
-    fn to_string(&self) -> String {
-        match *self {
-            TokenType::Token(ref t) => format!("`{}`", pprust::token_kind_to_string(t)),
-            TokenType::Keyword(kw) => format!("`{}`", kw),
-            TokenType::Operator => "an operator".to_string(),
-            TokenType::Lifetime => "lifetime".to_string(),
-            TokenType::Ident => "identifier".to_string(),
-            TokenType::Path => "path".to_string(),
-            TokenType::Type => "type".to_string(),
-            TokenType::Const => "const".to_string(),
-        }
-    }
-}
-
-#[derive(Copy, Clone, Debug)]
-enum TokenExpectType {
-    Expect,
-    NoExpect,
-}
-
-/// A sequence separator.
-struct SeqSep {
-    /// The separator token.
-    sep: Option<TokenKind>,
-    /// `true` if a trailing separator is allowed.
-    trailing_sep_allowed: bool,
-}
-
-impl SeqSep {
-    fn trailing_allowed(t: TokenKind) -> SeqSep {
-        SeqSep {
-            sep: Some(t),
-            trailing_sep_allowed: true,
-        }
-    }
-
-    fn none() -> SeqSep {
-        SeqSep {
-            sep: None,
-            trailing_sep_allowed: false,
-        }
-    }
-}
-
-impl<'a> Parser<'a> {
-    pub fn new(
-        sess: &'a ParseSess,
-        tokens: TokenStream,
-        directory: Option<Directory<'a>>,
-        recurse_into_file_modules: bool,
-        desugar_doc_comments: bool,
-        subparser_name: Option<&'static str>,
-    ) -> Self {
-        let mut parser = Parser {
-            sess,
-            token: Token::dummy(),
-            prev_span: DUMMY_SP,
-            meta_var_span: None,
-            prev_token_kind: PrevTokenKind::Other,
-            restrictions: Restrictions::empty(),
-            recurse_into_file_modules,
-            directory: Directory {
-                path: Cow::from(PathBuf::new()),
-                ownership: DirectoryOwnership::Owned { relative: None }
-            },
-            root_module_name: None,
-            expected_tokens: Vec::new(),
-            token_cursor: TokenCursor {
-                frame: TokenCursorFrame::new(
-                    DelimSpan::dummy(),
-                    token::NoDelim,
-                    &tokens.into(),
-                ),
-                stack: Vec::new(),
-            },
-            desugar_doc_comments,
-            cfg_mods: true,
-            unmatched_angle_bracket_count: 0,
-            max_angle_bracket_count: 0,
-            unclosed_delims: Vec::new(),
-            last_unexpected_token_span: None,
-            last_type_ascription: None,
-            subparser_name,
-        };
-
-        parser.token = parser.next_tok();
-
-        if let Some(directory) = directory {
-            parser.directory = directory;
-        } else if !parser.token.span.is_dummy() {
-            if let Some(FileName::Real(path)) =
-                    &sess.source_map().lookup_char_pos(parser.token.span.lo()).file.unmapped_path {
-                if let Some(directory_path) = path.parent() {
-                    parser.directory.path = Cow::from(directory_path.to_path_buf());
-                }
-            }
-        }
-
-        parser.process_potential_macro_variable();
-        parser
-    }
-
-    fn next_tok(&mut self) -> Token {
-        let mut next = if self.desugar_doc_comments {
-            self.token_cursor.next_desugared()
-        } else {
-            self.token_cursor.next()
-        };
-        if next.span.is_dummy() {
-            // Tweak the location for better diagnostics, but keep syntactic context intact.
-            next.span = self.prev_span.with_ctxt(next.span.ctxt());
-        }
-        next
-    }
-
-    /// Converts the current token to a string using `self`'s reader.
-    pub fn this_token_to_string(&self) -> String {
-        pprust::token_to_string(&self.token)
-    }
-
-    fn token_descr(&self) -> Option<&'static str> {
-        Some(match &self.token.kind {
-            _ if self.token.is_special_ident() => "reserved identifier",
-            _ if self.token.is_used_keyword() => "keyword",
-            _ if self.token.is_unused_keyword() => "reserved keyword",
-            token::DocComment(..) => "doc comment",
-            _ => return None,
-        })
-    }
-
-    pub(super) fn this_token_descr(&self) -> String {
-        if let Some(prefix) = self.token_descr() {
-            format!("{} `{}`", prefix, self.this_token_to_string())
-        } else {
-            format!("`{}`", self.this_token_to_string())
-        }
-    }
-
-    crate fn unexpected<T>(&mut self) -> PResult<'a, T> {
-        match self.expect_one_of(&[], &[]) {
-            Err(e) => Err(e),
-            Ok(_) => unreachable!(),
-        }
-    }
-
-    /// Expects and consumes the token `t`. Signals an error if the next token is not `t`.
-    pub fn expect(&mut self, t: &TokenKind) -> PResult<'a, bool /* recovered */> {
-        if self.expected_tokens.is_empty() {
-            if self.token == *t {
-                self.bump();
-                Ok(false)
-            } else {
-                self.unexpected_try_recover(t)
-            }
-        } else {
-            self.expect_one_of(slice::from_ref(t), &[])
-        }
-    }
-
-    /// Expect next token to be edible or inedible token.  If edible,
-    /// then consume it; if inedible, then return without consuming
-    /// anything.  Signal a fatal error if next token is unexpected.
-    pub fn expect_one_of(
-        &mut self,
-        edible: &[TokenKind],
-        inedible: &[TokenKind],
-    ) -> PResult<'a, bool /* recovered */> {
-        if edible.contains(&self.token.kind) {
-            self.bump();
-            Ok(false)
-        } else if inedible.contains(&self.token.kind) {
-            // leave it in the input
-            Ok(false)
-        } else if self.last_unexpected_token_span == Some(self.token.span) {
-            FatalError.raise();
-        } else {
-            self.expected_one_of_not_found(edible, inedible)
-        }
-    }
-
-    fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
-        self.parse_ident_common(true)
-    }
-
-    fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, ast::Ident> {
-        match self.token.kind {
-            token::Ident(name, _) => {
-                if self.token.is_reserved_ident() {
-                    let mut err = self.expected_ident_found();
-                    if recover {
-                        err.emit();
-                    } else {
-                        return Err(err);
-                    }
-                }
-                let span = self.token.span;
-                self.bump();
-                Ok(Ident::new(name, span))
-            }
-            _ => {
-                Err(if self.prev_token_kind == PrevTokenKind::DocComment {
-                    self.span_fatal_err(self.prev_span, Error::UselessDocComment)
-                } else {
-                    self.expected_ident_found()
-                })
-            }
-        }
-    }
-
-    /// Checks if the next token is `tok`, and returns `true` if so.
-    ///
-    /// This method will automatically add `tok` to `expected_tokens` if `tok` is not
-    /// encountered.
-    fn check(&mut self, tok: &TokenKind) -> bool {
-        let is_present = self.token == *tok;
-        if !is_present { self.expected_tokens.push(TokenType::Token(tok.clone())); }
-        is_present
-    }
-
-    /// Consumes a token 'tok' if it exists. Returns whether the given token was present.
-    pub fn eat(&mut self, tok: &TokenKind) -> bool {
-        let is_present = self.check(tok);
-        if is_present { self.bump() }
-        is_present
-    }
-
-    /// If the next token is the given keyword, returns `true` without eating it.
-    /// An expectation is also added for diagnostics purposes.
-    fn check_keyword(&mut self, kw: Symbol) -> bool {
-        self.expected_tokens.push(TokenType::Keyword(kw));
-        self.token.is_keyword(kw)
-    }
-
-    /// If the next token is the given keyword, eats it and returns `true`.
-    /// Otherwise, returns `false`. An expectation is also added for diagnostics purposes.
-    fn eat_keyword(&mut self, kw: Symbol) -> bool {
-        if self.check_keyword(kw) {
-            self.bump();
-            true
-        } else {
-            false
-        }
-    }
-
-    fn eat_keyword_noexpect(&mut self, kw: Symbol) -> bool {
-        if self.token.is_keyword(kw) {
-            self.bump();
-            true
-        } else {
-            false
-        }
-    }
-
-    /// If the given word is not a keyword, signals an error.
-    /// If the next token is not the given word, signals an error.
-    /// Otherwise, eats it.
-    fn expect_keyword(&mut self, kw: Symbol) -> PResult<'a, ()> {
-        if !self.eat_keyword(kw) {
-            self.unexpected()
-        } else {
-            Ok(())
-        }
-    }
-
-    fn check_or_expected(&mut self, ok: bool, typ: TokenType) -> bool {
-        if ok {
-            true
-        } else {
-            self.expected_tokens.push(typ);
-            false
-        }
-    }
-
-    fn check_ident(&mut self) -> bool {
-        self.check_or_expected(self.token.is_ident(), TokenType::Ident)
-    }
-
-    fn check_path(&mut self) -> bool {
-        self.check_or_expected(self.token.is_path_start(), TokenType::Path)
-    }
-
-    fn check_type(&mut self) -> bool {
-        self.check_or_expected(self.token.can_begin_type(), TokenType::Type)
-    }
-
-    fn check_const_arg(&mut self) -> bool {
-        self.check_or_expected(self.token.can_begin_const_arg(), TokenType::Const)
-    }
-
-    /// Checks to see if the next token is either `+` or `+=`.
-    /// Otherwise returns `false`.
-    fn check_plus(&mut self) -> bool {
-        self.check_or_expected(
-            self.token.is_like_plus(),
-            TokenType::Token(token::BinOp(token::Plus)),
-        )
-    }
-
-    /// Expects and consumes a `+`. if `+=` is seen, replaces it with a `=`
-    /// and continues. If a `+` is not seen, returns `false`.
-    ///
-    /// This is used when token-splitting `+=` into `+`.
-    /// See issue #47856 for an example of when this may occur.
-    fn eat_plus(&mut self) -> bool {
-        self.expected_tokens.push(TokenType::Token(token::BinOp(token::Plus)));
-        match self.token.kind {
-            token::BinOp(token::Plus) => {
-                self.bump();
-                true
-            }
-            token::BinOpEq(token::Plus) => {
-                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
-                self.bump_with(token::Eq, span);
-                true
-            }
-            _ => false,
-        }
-    }
-
-    /// Expects and consumes an `&`. If `&&` is seen, replaces it with a single
-    /// `&` and continues. If an `&` is not seen, signals an error.
-    fn expect_and(&mut self) -> PResult<'a, ()> {
-        self.expected_tokens.push(TokenType::Token(token::BinOp(token::And)));
-        match self.token.kind {
-            token::BinOp(token::And) => {
-                self.bump();
-                Ok(())
-            }
-            token::AndAnd => {
-                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
-                Ok(self.bump_with(token::BinOp(token::And), span))
-            }
-            _ => self.unexpected()
-        }
-    }
-
-    /// Expects and consumes an `|`. If `||` is seen, replaces it with a single
-    /// `|` and continues. If an `|` is not seen, signals an error.
-    fn expect_or(&mut self) -> PResult<'a, ()> {
-        self.expected_tokens.push(TokenType::Token(token::BinOp(token::Or)));
-        match self.token.kind {
-            token::BinOp(token::Or) => {
-                self.bump();
-                Ok(())
-            }
-            token::OrOr => {
-                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
-                Ok(self.bump_with(token::BinOp(token::Or), span))
-            }
-            _ => self.unexpected()
-        }
-    }
-
-    /// Attempts to consume a `<`. If `<<` is seen, replaces it with a single
-    /// `<` and continue. If `<-` is seen, replaces it with a single `<`
-    /// and continue. If a `<` is not seen, returns false.
-    ///
-    /// This is meant to be used when parsing generics on a path to get the
-    /// starting token.
-    fn eat_lt(&mut self) -> bool {
-        self.expected_tokens.push(TokenType::Token(token::Lt));
-        let ate = match self.token.kind {
-            token::Lt => {
-                self.bump();
-                true
-            }
-            token::BinOp(token::Shl) => {
-                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
-                self.bump_with(token::Lt, span);
-                true
-            }
-            token::LArrow => {
-                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
-                self.bump_with(token::BinOp(token::Minus), span);
-                true
-            }
-            _ => false,
-        };
-
-        if ate {
-            // See doc comment for `unmatched_angle_bracket_count`.
-            self.unmatched_angle_bracket_count += 1;
-            self.max_angle_bracket_count += 1;
-            debug!("eat_lt: (increment) count={:?}", self.unmatched_angle_bracket_count);
-        }
-
-        ate
-    }
-
-    fn expect_lt(&mut self) -> PResult<'a, ()> {
-        if !self.eat_lt() {
-            self.unexpected()
-        } else {
-            Ok(())
-        }
-    }
-
-    /// Expects and consumes a single `>` token. if a `>>` is seen, replaces it
-    /// with a single `>` and continues. If a `>` is not seen, signals an error.
-    fn expect_gt(&mut self) -> PResult<'a, ()> {
-        self.expected_tokens.push(TokenType::Token(token::Gt));
-        let ate = match self.token.kind {
-            token::Gt => {
-                self.bump();
-                Some(())
-            }
-            token::BinOp(token::Shr) => {
-                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
-                Some(self.bump_with(token::Gt, span))
-            }
-            token::BinOpEq(token::Shr) => {
-                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
-                Some(self.bump_with(token::Ge, span))
-            }
-            token::Ge => {
-                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
-                Some(self.bump_with(token::Eq, span))
-            }
-            _ => None,
-        };
-
-        match ate {
-            Some(_) => {
-                // See doc comment for `unmatched_angle_bracket_count`.
-                if self.unmatched_angle_bracket_count > 0 {
-                    self.unmatched_angle_bracket_count -= 1;
-                    debug!("expect_gt: (decrement) count={:?}", self.unmatched_angle_bracket_count);
-                }
-
-                Ok(())
-            },
-            None => self.unexpected(),
-        }
-    }
-
-    /// Parses a sequence, including the closing delimiter. The function
-    /// `f` must consume tokens until reaching the next separator or
-    /// closing bracket.
-    fn parse_seq_to_end<T>(
-        &mut self,
-        ket: &TokenKind,
-        sep: SeqSep,
-        f: impl FnMut(&mut Parser<'a>) -> PResult<'a,  T>,
-    ) -> PResult<'a, Vec<T>> {
-        let (val, _, recovered) = self.parse_seq_to_before_end(ket, sep, f)?;
-        if !recovered {
-            self.bump();
-        }
-        Ok(val)
-    }
-
-    /// Parses a sequence, not including the closing delimiter. The function
-    /// `f` must consume tokens until reaching the next separator or
-    /// closing bracket.
-    fn parse_seq_to_before_end<T>(
-        &mut self,
-        ket: &TokenKind,
-        sep: SeqSep,
-        f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
-    ) -> PResult<'a, (Vec<T>, bool, bool)> {
-        self.parse_seq_to_before_tokens(&[ket], sep, TokenExpectType::Expect, f)
-    }
-
-    fn expect_any_with_type(&mut self, kets: &[&TokenKind], expect: TokenExpectType) -> bool {
-        kets.iter().any(|k| {
-            match expect {
-                TokenExpectType::Expect => self.check(k),
-                TokenExpectType::NoExpect => self.token == **k,
-            }
-        })
-    }
-
-    fn parse_seq_to_before_tokens<T>(
-        &mut self,
-        kets: &[&TokenKind],
-        sep: SeqSep,
-        expect: TokenExpectType,
-        mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
-    ) -> PResult<'a, (Vec<T>, bool /* trailing */, bool /* recovered */)> {
-        let mut first = true;
-        let mut recovered = false;
-        let mut trailing = false;
-        let mut v = vec![];
-        while !self.expect_any_with_type(kets, expect) {
-            if let token::CloseDelim(..) | token::Eof = self.token.kind {
-                break
-            }
-            if let Some(ref t) = sep.sep {
-                if first {
-                    first = false;
-                } else {
-                    match self.expect(t) {
-                        Ok(false) => {}
-                        Ok(true) => {
-                            recovered = true;
-                            break;
-                        }
-                        Err(mut e) => {
-                            // Attempt to keep parsing if it was a similar separator.
-                            if let Some(ref tokens) = t.similar_tokens() {
-                                if tokens.contains(&self.token.kind) {
-                                    self.bump();
-                                }
-                            }
-                            e.emit();
-                            // Attempt to keep parsing if it was an omitted separator.
-                            match f(self) {
-                                Ok(t) => {
-                                    v.push(t);
-                                    continue;
-                                },
-                                Err(mut e) => {
-                                    e.cancel();
-                                    break;
-                                }
-                            }
-                        }
-                    }
-                }
-            }
-            if sep.trailing_sep_allowed && self.expect_any_with_type(kets, expect) {
-                trailing = true;
-                break;
-            }
-
-            let t = f(self)?;
-            v.push(t);
-        }
-
-        Ok((v, trailing, recovered))
-    }
-
-    /// Parses a sequence, including the closing delimiter. The function
-    /// `f` must consume tokens until reaching the next separator or
-    /// closing bracket.
-    fn parse_unspanned_seq<T>(
-        &mut self,
-        bra: &TokenKind,
-        ket: &TokenKind,
-        sep: SeqSep,
-        f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
-    ) -> PResult<'a, (Vec<T>, bool)> {
-        self.expect(bra)?;
-        let (result, trailing, recovered) = self.parse_seq_to_before_end(ket, sep, f)?;
-        if !recovered {
-            self.eat(ket);
-        }
-        Ok((result, trailing))
-    }
-
-    fn parse_delim_comma_seq<T>(
-        &mut self,
-        delim: DelimToken,
-        f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
-    ) -> PResult<'a, (Vec<T>, bool)> {
-        self.parse_unspanned_seq(
-            &token::OpenDelim(delim),
-            &token::CloseDelim(delim),
-            SeqSep::trailing_allowed(token::Comma),
-            f,
-        )
-    }
-
-    fn parse_paren_comma_seq<T>(
-        &mut self,
-        f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
-    ) -> PResult<'a, (Vec<T>, bool)> {
-        self.parse_delim_comma_seq(token::Paren, f)
-    }
-
-    /// Advance the parser by one token.
-    pub fn bump(&mut self) {
-        if self.prev_token_kind == PrevTokenKind::Eof {
-            // Bumping after EOF is a bad sign, usually an infinite loop.
-            self.bug("attempted to bump the parser past EOF (may be stuck in a loop)");
-        }
-
-        self.prev_span = self.meta_var_span.take().unwrap_or(self.token.span);
-
-        // Record last token kind for possible error recovery.
-        self.prev_token_kind = match self.token.kind {
-            token::DocComment(..) => PrevTokenKind::DocComment,
-            token::Comma => PrevTokenKind::Comma,
-            token::BinOp(token::Plus) => PrevTokenKind::Plus,
-            token::BinOp(token::Or) => PrevTokenKind::BitOr,
-            token::Interpolated(..) => PrevTokenKind::Interpolated,
-            token::Eof => PrevTokenKind::Eof,
-            token::Ident(..) => PrevTokenKind::Ident,
-            _ => PrevTokenKind::Other,
-        };
-
-        self.token = self.next_tok();
-        self.expected_tokens.clear();
-        // Check after each token.
-        self.process_potential_macro_variable();
-    }
-
-    /// Advances the parser using provided token as a next one. Use this when
-    /// consuming a part of a token. For example a single `<` from `<<`.
-    fn bump_with(&mut self, next: TokenKind, span: Span) {
-        self.prev_span = self.token.span.with_hi(span.lo());
-        // It would be incorrect to record the kind of the current token, but
-        // fortunately for tokens currently using `bump_with`, the
-        // `prev_token_kind` will be of no use anyway.
-        self.prev_token_kind = PrevTokenKind::Other;
-        self.token = Token::new(next, span);
-        self.expected_tokens.clear();
-    }
-
-    /// Look-ahead `dist` tokens of `self.token` and get access to that token there.
-    /// When `dist == 0` then the current token is looked at.
-    pub fn look_ahead<R>(&self, dist: usize, looker: impl FnOnce(&Token) -> R) -> R {
-        if dist == 0 {
-            return looker(&self.token);
-        }
-
-        let frame = &self.token_cursor.frame;
-        looker(&match frame.tree_cursor.look_ahead(dist - 1) {
-            Some(tree) => match tree {
-                TokenTree::Token(token) => token,
-                TokenTree::Delimited(dspan, delim, _) =>
-                    Token::new(token::OpenDelim(delim), dspan.open),
-            }
-            None => Token::new(token::CloseDelim(frame.delim), frame.span.close)
-        })
-    }
-
-    /// Returns whether any of the given keywords are `dist` tokens ahead of the current one.
-    fn is_keyword_ahead(&self, dist: usize, kws: &[Symbol]) -> bool {
-        self.look_ahead(dist, |t| kws.iter().any(|&kw| t.is_keyword(kw)))
-    }
-
-    /// Parses asyncness: `async` or nothing.
-    fn parse_asyncness(&mut self) -> IsAsync {
-        if self.eat_keyword(kw::Async) {
-            IsAsync::Async {
-                closure_id: DUMMY_NODE_ID,
-                return_impl_trait_id: DUMMY_NODE_ID,
-            }
-        } else {
-            IsAsync::NotAsync
-        }
-    }
-
-    /// Parses unsafety: `unsafe` or nothing.
-    fn parse_unsafety(&mut self) -> Unsafety {
-        if self.eat_keyword(kw::Unsafe) {
-            Unsafety::Unsafe
-        } else {
-            Unsafety::Normal
-        }
-    }
-
-    /// Parses mutability (`mut` or nothing).
-    fn parse_mutability(&mut self) -> Mutability {
-        if self.eat_keyword(kw::Mut) {
-            Mutability::Mutable
-        } else {
-            Mutability::Immutable
-        }
-    }
-
-    /// Possibly parses mutability (`const` or `mut`).
-    fn parse_const_or_mut(&mut self) -> Option<Mutability> {
-        if self.eat_keyword(kw::Mut) {
-            Some(Mutability::Mutable)
-        } else if self.eat_keyword(kw::Const) {
-            Some(Mutability::Immutable)
-        } else {
-            None
-        }
-    }
-
-    fn parse_field_name(&mut self) -> PResult<'a, Ident> {
-        if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) =
-                self.token.kind {
-            self.expect_no_suffix(self.token.span, "a tuple index", suffix);
-            self.bump();
-            Ok(Ident::new(symbol, self.prev_span))
-        } else {
-            self.parse_ident_common(false)
-        }
-    }
-
-    fn expect_delimited_token_tree(&mut self) -> PResult<'a, (MacDelimiter, TokenStream)> {
-        let delim = match self.token.kind {
-            token::OpenDelim(delim) => delim,
-            _ => {
-                let msg = "expected open delimiter";
-                let mut err = self.fatal(msg);
-                err.span_label(self.token.span, msg);
-                return Err(err)
-            }
-        };
-        let tts = match self.parse_token_tree() {
-            TokenTree::Delimited(_, _, tts) => tts,
-            _ => unreachable!(),
-        };
-        let delim = match delim {
-            token::Paren => MacDelimiter::Parenthesis,
-            token::Bracket => MacDelimiter::Bracket,
-            token::Brace => MacDelimiter::Brace,
-            token::NoDelim => self.bug("unexpected no delimiter"),
-        };
-        Ok((delim, tts.into()))
-    }
-
-    fn parse_or_use_outer_attributes(
-        &mut self,
-        already_parsed_attrs: Option<ThinVec<Attribute>>,
-    ) -> PResult<'a, ThinVec<Attribute>> {
-        if let Some(attrs) = already_parsed_attrs {
-            Ok(attrs)
-        } else {
-            self.parse_outer_attributes().map(|a| a.into())
-        }
-    }
-
-    pub fn process_potential_macro_variable(&mut self) {
-        self.token = match self.token.kind {
-            token::Dollar if self.token.span.from_expansion() &&
-                             self.look_ahead(1, |t| t.is_ident()) => {
-                self.bump();
-                let name = match self.token.kind {
-                    token::Ident(name, _) => name,
-                    _ => unreachable!()
-                };
-                let span = self.prev_span.to(self.token.span);
-                self.diagnostic()
-                    .struct_span_fatal(span, &format!("unknown macro variable `{}`", name))
-                    .span_label(span, "unknown macro variable")
-                    .emit();
-                self.bump();
-                return
-            }
-            token::Interpolated(ref nt) => {
-                self.meta_var_span = Some(self.token.span);
-                // Interpolated identifier and lifetime tokens are replaced with usual identifier
-                // and lifetime tokens, so the former are never encountered during normal parsing.
-                match **nt {
-                    token::NtIdent(ident, is_raw) =>
-                        Token::new(token::Ident(ident.name, is_raw), ident.span),
-                    token::NtLifetime(ident) =>
-                        Token::new(token::Lifetime(ident.name), ident.span),
-                    _ => return,
-                }
-            }
-            _ => return,
-        };
-    }
-
-    /// Parses a single token tree from the input.
-    pub fn parse_token_tree(&mut self) -> TokenTree {
-        match self.token.kind {
-            token::OpenDelim(..) => {
-                let frame = mem::replace(&mut self.token_cursor.frame,
-                                         self.token_cursor.stack.pop().unwrap());
-                self.token.span = frame.span.entire();
-                self.bump();
-                TokenTree::Delimited(
-                    frame.span,
-                    frame.delim,
-                    frame.tree_cursor.stream.into(),
-                )
-            },
-            token::CloseDelim(_) | token::Eof => unreachable!(),
-            _ => {
-                let token = self.token.take();
-                self.bump();
-                TokenTree::Token(token)
-            }
-        }
-    }
-
-    /// Parses a stream of tokens into a list of `TokenTree`s, up to EOF.
-    pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
-        let mut tts = Vec::new();
-        while self.token != token::Eof {
-            tts.push(self.parse_token_tree());
-        }
-        Ok(tts)
-    }
-
-    pub fn parse_tokens(&mut self) -> TokenStream {
-        let mut result = Vec::new();
-        loop {
-            match self.token.kind {
-                token::Eof | token::CloseDelim(..) => break,
-                _ => result.push(self.parse_token_tree().into()),
-            }
-        }
-        TokenStream::new(result)
-    }
-
-    /// Evaluates the closure with restrictions in place.
-    ///
-    /// Afters the closure is evaluated, restrictions are reset.
-    fn with_res<T>(&mut self, res: Restrictions, f: impl FnOnce(&mut Self) -> T) -> T {
-        let old = self.restrictions;
-        self.restrictions = res;
-        let res = f(self);
-        self.restrictions = old;
-        res
-    }
-
-    fn is_crate_vis(&self) -> bool {
-        self.token.is_keyword(kw::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
-    }
-
-    /// Parses `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `crate` for `pub(crate)`,
-    /// `pub(self)` for `pub(in self)` and `pub(super)` for `pub(in super)`.
-    /// If the following element can't be a tuple (i.e., it's a function definition), then
-    /// it's not a tuple struct field), and the contents within the parentheses isn't valid,
-    /// so emit a proper diagnostic.
-    pub fn parse_visibility(&mut self, can_take_tuple: bool) -> PResult<'a, Visibility> {
-        maybe_whole!(self, NtVis, |x| x);
-
-        self.expected_tokens.push(TokenType::Keyword(kw::Crate));
-        if self.is_crate_vis() {
-            self.bump(); // `crate`
-            self.sess.gated_spans.gate(sym::crate_visibility_modifier, self.prev_span);
-            return Ok(respan(self.prev_span, VisibilityKind::Crate(CrateSugar::JustCrate)));
-        }
-
-        if !self.eat_keyword(kw::Pub) {
-            // We need a span for our `Spanned<VisibilityKind>`, but there's inherently no
-            // keyword to grab a span from for inherited visibility; an empty span at the
-            // beginning of the current token would seem to be the "Schelling span".
-            return Ok(respan(self.token.span.shrink_to_lo(), VisibilityKind::Inherited))
-        }
-        let lo = self.prev_span;
-
-        if self.check(&token::OpenDelim(token::Paren)) {
-            // We don't `self.bump()` the `(` yet because this might be a struct definition where
-            // `()` or a tuple might be allowed. For example, `struct Struct(pub (), pub (usize));`.
-            // Because of this, we only `bump` the `(` if we're assured it is appropriate to do so
-            // by the following tokens.
-            if self.is_keyword_ahead(1, &[kw::Crate])
-                && self.look_ahead(2, |t| t != &token::ModSep) // account for `pub(crate::foo)`
-            {
-                // Parse `pub(crate)`.
-                self.bump(); // `(`
-                self.bump(); // `crate`
-                self.expect(&token::CloseDelim(token::Paren))?; // `)`
-                let vis = VisibilityKind::Crate(CrateSugar::PubCrate);
-                return Ok(respan(lo.to(self.prev_span), vis));
-            } else if self.is_keyword_ahead(1, &[kw::In]) {
-                // Parse `pub(in path)`.
-                self.bump(); // `(`
-                self.bump(); // `in`
-                let path = self.parse_path(PathStyle::Mod)?; // `path`
-                self.expect(&token::CloseDelim(token::Paren))?; // `)`
-                let vis = VisibilityKind::Restricted {
-                    path: P(path),
-                    id: ast::DUMMY_NODE_ID,
-                };
-                return Ok(respan(lo.to(self.prev_span), vis));
-            } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren))
-                && self.is_keyword_ahead(1, &[kw::Super, kw::SelfLower])
-            {
-                // Parse `pub(self)` or `pub(super)`.
-                self.bump(); // `(`
-                let path = self.parse_path(PathStyle::Mod)?; // `super`/`self`
-                self.expect(&token::CloseDelim(token::Paren))?; // `)`
-                let vis = VisibilityKind::Restricted {
-                    path: P(path),
-                    id: ast::DUMMY_NODE_ID,
-                };
-                return Ok(respan(lo.to(self.prev_span), vis));
-            } else if !can_take_tuple { // Provide this diagnostic if this is not a tuple struct.
-                self.recover_incorrect_vis_restriction()?;
-                // Emit diagnostic, but continue with public visibility.
-            }
-        }
-
-        Ok(respan(lo, VisibilityKind::Public))
-    }
-
-    /// Recovery for e.g. `pub(something) fn ...` or `struct X { pub(something) y: Z }`
-    fn recover_incorrect_vis_restriction(&mut self) -> PResult<'a, ()> {
-        self.bump(); // `(`
-        let path = self.parse_path(PathStyle::Mod)?;
-        self.expect(&token::CloseDelim(token::Paren))?;  // `)`
-
-        let msg = "incorrect visibility restriction";
-        let suggestion = r##"some possible visibility restrictions are:
-`pub(crate)`: visible only on the current crate
-`pub(super)`: visible only in the current module's parent
-`pub(in path::to::module)`: visible only on the specified path"##;
-
-        let path_str = pprust::path_to_string(&path);
-
-        struct_span_err!(self.sess.span_diagnostic, path.span, E0704, "{}", msg)
-            .help(suggestion)
-            .span_suggestion(
-                path.span,
-                &format!("make this visible only to module `{}` with `in`", path_str),
-                format!("in {}", path_str),
-                Applicability::MachineApplicable,
-            )
-            .emit();
-
-        Ok(())
-    }
-
-    /// Parses `extern string_literal?`.
-    /// If `extern` is not found, the Rust ABI is used.
-    /// If `extern` is found and a `string_literal` does not follow, the C ABI is used.
-    fn parse_extern_abi(&mut self) -> PResult<'a, Abi> {
-        Ok(if self.eat_keyword(kw::Extern) {
-            self.parse_opt_abi()?
-        } else {
-            Abi::default()
-        })
-    }
-
-    /// Parses a string literal as an ABI spec.
-    /// If one is not found, the "C" ABI is used.
-    fn parse_opt_abi(&mut self) -> PResult<'a, Abi> {
-        let span = if self.token.can_begin_literal_or_bool() {
-            let ast::Lit { span, kind, .. } = self.parse_lit()?;
-            match kind {
-                ast::LitKind::Str(symbol, _) => return Ok(Abi::new(symbol, span)),
-                ast::LitKind::Err(_) => {}
-                _ => {
-                    self.struct_span_err(span, "non-string ABI literal")
-                        .span_suggestion(
-                            span,
-                            "specify the ABI with a string literal",
-                            "\"C\"".to_string(),
-                            Applicability::MaybeIncorrect,
-                        )
-                        .emit();
-                }
-            }
-            span
-        } else {
-            self.prev_span
-        };
-        Ok(Abi::new(sym::C, span))
-    }
-
-    /// We are parsing `async fn`. If we are on Rust 2015, emit an error.
-    fn ban_async_in_2015(&self, async_span: Span) {
-        if async_span.rust_2015() {
-            self.diagnostic()
-                .struct_span_err_with_code(
-                    async_span,
-                    "`async fn` is not permitted in the 2015 edition",
-                    DiagnosticId::Error("E0670".into())
-                )
-                .emit();
-        }
-    }
-
-    fn collect_tokens<R>(
-        &mut self,
-        f: impl FnOnce(&mut Self) -> PResult<'a, R>,
-    ) -> PResult<'a, (R, TokenStream)> {
-        // Record all tokens we parse when parsing this item.
-        let mut tokens = Vec::new();
-        let prev_collecting = match self.token_cursor.frame.last_token {
-            LastToken::Collecting(ref mut list) => {
-                Some(mem::take(list))
-            }
-            LastToken::Was(ref mut last) => {
-                tokens.extend(last.take());
-                None
-            }
-        };
-        self.token_cursor.frame.last_token = LastToken::Collecting(tokens);
-        let prev = self.token_cursor.stack.len();
-        let ret = f(self);
-        let last_token = if self.token_cursor.stack.len() == prev {
-            &mut self.token_cursor.frame.last_token
-        } else if self.token_cursor.stack.get(prev).is_none() {
-            // This can happen due to a bad interaction of two unrelated recovery mechanisms with
-            // mismatched delimiters *and* recovery lookahead on the likely typo `pub ident(`
-            // (#62881).
-            return Ok((ret?, TokenStream::default()));
-        } else {
-            &mut self.token_cursor.stack[prev].last_token
-        };
-
-        // Pull out the tokens that we've collected from the call to `f` above.
-        let mut collected_tokens = match *last_token {
-            LastToken::Collecting(ref mut v) => mem::take(v),
-            LastToken::Was(ref was) => {
-                let msg = format!("our vector went away? - found Was({:?})", was);
-                debug!("collect_tokens: {}", msg);
-                self.sess.span_diagnostic.delay_span_bug(self.token.span, &msg);
-                // This can happen due to a bad interaction of two unrelated recovery mechanisms
-                // with mismatched delimiters *and* recovery lookahead on the likely typo
-                // `pub ident(` (#62895, different but similar to the case above).
-                return Ok((ret?, TokenStream::default()));
-            }
-        };
-
-        // If we're not at EOF our current token wasn't actually consumed by
-        // `f`, but it'll still be in our list that we pulled out. In that case
-        // put it back.
-        let extra_token = if self.token != token::Eof {
-            collected_tokens.pop()
-        } else {
-            None
-        };
-
-        // If we were previously collecting tokens, then this was a recursive
-        // call. In that case we need to record all the tokens we collected in
-        // our parent list as well. To do that we push a clone of our stream
-        // onto the previous list.
-        match prev_collecting {
-            Some(mut list) => {
-                list.extend(collected_tokens.iter().cloned());
-                list.extend(extra_token);
-                *last_token = LastToken::Collecting(list);
-            }
-            None => {
-                *last_token = LastToken::Was(extra_token);
-            }
-        }
-
-        Ok((ret?, TokenStream::new(collected_tokens)))
-    }
-
-    /// `::{` or `::*`
-    fn is_import_coupler(&mut self) -> bool {
-        self.check(&token::ModSep) &&
-            self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace) ||
-                                   *t == token::BinOp(token::Star))
-    }
-
-    fn parse_optional_str(&mut self) -> Option<(Symbol, ast::StrStyle, Option<ast::Name>)> {
-        let ret = match self.token.kind {
-            token::Literal(token::Lit { kind: token::Str, symbol, suffix }) =>
-                (symbol, ast::StrStyle::Cooked, suffix),
-            token::Literal(token::Lit { kind: token::StrRaw(n), symbol, suffix }) =>
-                (symbol, ast::StrStyle::Raw(n), suffix),
-            _ => return None
-        };
-        self.bump();
-        Some(ret)
-    }
-
-    pub fn parse_str(&mut self) -> PResult<'a, (Symbol, StrStyle)> {
-        match self.parse_optional_str() {
-            Some((s, style, suf)) => {
-                let sp = self.prev_span;
-                self.expect_no_suffix(sp, "a string literal", suf);
-                Ok((s, style))
-            }
-            _ => {
-                let msg = "expected string literal";
-                let mut err = self.fatal(msg);
-                err.span_label(self.token.span, msg);
-                Err(err)
-            }
-        }
-    }
-}
-
-crate fn make_unclosed_delims_error(
-    unmatched: UnmatchedBrace,
-    sess: &ParseSess,
-) -> Option<DiagnosticBuilder<'_>> {
-    // `None` here means an `Eof` was found. We already emit those errors elsewhere, we add them to
-    // `unmatched_braces` only for error recovery in the `Parser`.
-    let found_delim = unmatched.found_delim?;
-    let mut err = sess.span_diagnostic.struct_span_err(unmatched.found_span, &format!(
-        "incorrect close delimiter: `{}`",
-        pprust::token_kind_to_string(&token::CloseDelim(found_delim)),
-    ));
-    err.span_label(unmatched.found_span, "incorrect close delimiter");
-    if let Some(sp) = unmatched.candidate_span {
-        err.span_label(sp, "close delimiter possibly meant for this");
-    }
-    if let Some(sp) = unmatched.unclosed_span {
-        err.span_label(sp, "un-closed delimiter");
-    }
-    Some(err)
-}
-
-pub fn emit_unclosed_delims(unclosed_delims: &mut Vec<UnmatchedBrace>, sess: &ParseSess) {
-    *sess.reached_eof.borrow_mut() |= unclosed_delims.iter()
-        .any(|unmatched_delim| unmatched_delim.found_delim.is_none());
-    for unmatched in unclosed_delims.drain(..) {
-        make_unclosed_delims_error(unmatched, sess).map(|mut e| e.emit());
-    }
-}
diff --git a/src/libsyntax/parse/parser/module.rs b/src/libsyntax/parse/parser/module.rs
deleted file mode 100644
index ad72b3a1dea..00000000000
--- a/src/libsyntax/parse/parser/module.rs
+++ /dev/null
@@ -1,315 +0,0 @@
-use super::Parser;
-use super::item::ItemInfo;
-use super::diagnostics::Error;
-
-use crate::attr;
-use crate::ast::{self, Ident, Attribute, ItemKind, Mod, Crate};
-use crate::parse::{new_sub_parser_from_file, DirectoryOwnership};
-use crate::token::{self, TokenKind};
-use crate::source_map::{SourceMap, Span, DUMMY_SP, FileName};
-
-use syntax_pos::symbol::sym;
-use errors::PResult;
-
-use std::path::{self, Path, PathBuf};
-
-/// Information about the path to a module.
-pub(super) struct ModulePath {
-    name: String,
-    path_exists: bool,
-    pub result: Result<ModulePathSuccess, Error>,
-}
-
-pub(super) struct ModulePathSuccess {
-    pub path: PathBuf,
-    pub directory_ownership: DirectoryOwnership,
-}
-
-impl<'a> Parser<'a> {
-    /// Parses a source module as a crate. This is the main entry point for the parser.
-    pub fn parse_crate_mod(&mut self) -> PResult<'a, Crate> {
-        let lo = self.token.span;
-        let krate = Ok(ast::Crate {
-            attrs: self.parse_inner_attributes()?,
-            module: self.parse_mod_items(&token::Eof, lo)?,
-            span: lo.to(self.token.span),
-        });
-        krate
-    }
-
-    /// Parses a `mod <foo> { ... }` or `mod <foo>;` item.
-    pub(super) fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
-        // HACK(Centril): See documentation on `ParseSess::process_cfg_mod`.
-        let (in_cfg, outer_attrs) = (self.sess.process_cfg_mod)(
-            self.sess,
-            self.cfg_mods,
-            outer_attrs,
-        );
-
-        let id_span = self.token.span;
-        let id = self.parse_ident()?;
-        if self.eat(&token::Semi) {
-            if in_cfg && self.recurse_into_file_modules {
-                // This mod is in an external file. Let's go get it!
-                let ModulePathSuccess { path, directory_ownership } =
-                    self.submod_path(id, &outer_attrs, id_span)?;
-                let (module, attrs) =
-                    self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?;
-                Ok((id, ItemKind::Mod(module), Some(attrs)))
-            } else {
-                let placeholder = ast::Mod {
-                    inner: DUMMY_SP,
-                    items: Vec::new(),
-                    inline: false
-                };
-                Ok((id, ItemKind::Mod(placeholder), None))
-            }
-        } else {
-            let old_directory = self.directory.clone();
-            self.push_directory(id, &outer_attrs);
-
-            self.expect(&token::OpenDelim(token::Brace))?;
-            let mod_inner_lo = self.token.span;
-            let attrs = self.parse_inner_attributes()?;
-            let module = self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo)?;
-
-            self.directory = old_directory;
-            Ok((id, ItemKind::Mod(module), Some(attrs)))
-        }
-    }
-
-    /// Given a termination token, parses all of the items in a module.
-    fn parse_mod_items(&mut self, term: &TokenKind, inner_lo: Span) -> PResult<'a, Mod> {
-        let mut items = vec![];
-        while let Some(item) = self.parse_item()? {
-            items.push(item);
-            self.maybe_consume_incorrect_semicolon(&items);
-        }
-
-        if !self.eat(term) {
-            let token_str = self.this_token_descr();
-            if !self.maybe_consume_incorrect_semicolon(&items) {
-                let mut err = self.fatal(&format!("expected item, found {}", token_str));
-                err.span_label(self.token.span, "expected item");
-                return Err(err);
-            }
-        }
-
-        let hi = if self.token.span.is_dummy() {
-            inner_lo
-        } else {
-            self.prev_span
-        };
-
-        Ok(Mod {
-            inner: inner_lo.to(hi),
-            items,
-            inline: true
-        })
-    }
-
-    fn submod_path(
-        &mut self,
-        id: ast::Ident,
-        outer_attrs: &[Attribute],
-        id_sp: Span
-    ) -> PResult<'a, ModulePathSuccess> {
-        if let Some(path) = Parser::submod_path_from_attr(outer_attrs, &self.directory.path) {
-            return Ok(ModulePathSuccess {
-                directory_ownership: match path.file_name().and_then(|s| s.to_str()) {
-                    // All `#[path]` files are treated as though they are a `mod.rs` file.
-                    // This means that `mod foo;` declarations inside `#[path]`-included
-                    // files are siblings,
-                    //
-                    // Note that this will produce weirdness when a file named `foo.rs` is
-                    // `#[path]` included and contains a `mod foo;` declaration.
-                    // If you encounter this, it's your own darn fault :P
-                    Some(_) => DirectoryOwnership::Owned { relative: None },
-                    _ => DirectoryOwnership::UnownedViaMod,
-                },
-                path,
-            });
-        }
-
-        let relative = match self.directory.ownership {
-            DirectoryOwnership::Owned { relative } => relative,
-            DirectoryOwnership::UnownedViaBlock |
-            DirectoryOwnership::UnownedViaMod => None,
-        };
-        let paths = Parser::default_submod_path(
-                        id, relative, &self.directory.path, self.sess.source_map());
-
-        match self.directory.ownership {
-            DirectoryOwnership::Owned { .. } => {
-                paths.result.map_err(|err| self.span_fatal_err(id_sp, err))
-            },
-            DirectoryOwnership::UnownedViaBlock => {
-                let msg =
-                    "Cannot declare a non-inline module inside a block \
-                    unless it has a path attribute";
-                let mut err = self.diagnostic().struct_span_err(id_sp, msg);
-                if paths.path_exists {
-                    let msg = format!("Maybe `use` the module `{}` instead of redeclaring it",
-                                      paths.name);
-                    err.span_note(id_sp, &msg);
-                }
-                Err(err)
-            }
-            DirectoryOwnership::UnownedViaMod => {
-                let mut err = self.diagnostic().struct_span_err(id_sp,
-                    "cannot declare a new module at this location");
-                if !id_sp.is_dummy() {
-                    let src_path = self.sess.source_map().span_to_filename(id_sp);
-                    if let FileName::Real(src_path) = src_path {
-                        if let Some(stem) = src_path.file_stem() {
-                            let mut dest_path = src_path.clone();
-                            dest_path.set_file_name(stem);
-                            dest_path.push("mod.rs");
-                            err.span_note(id_sp,
-                                    &format!("maybe move this module `{}` to its own \
-                                                directory via `{}`", src_path.display(),
-                                            dest_path.display()));
-                        }
-                    }
-                }
-                if paths.path_exists {
-                    err.span_note(id_sp,
-                                  &format!("... or maybe `use` the module `{}` instead \
-                                            of possibly redeclaring it",
-                                           paths.name));
-                }
-                Err(err)
-            }
-        }
-    }
-
-    pub(super) fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> {
-        if let Some(s) = attr::first_attr_value_str_by_name(attrs, sym::path) {
-            let s = s.as_str();
-
-            // On windows, the base path might have the form
-            // `\\?\foo\bar` in which case it does not tolerate
-            // mixed `/` and `\` separators, so canonicalize
-            // `/` to `\`.
-            #[cfg(windows)]
-            let s = s.replace("/", "\\");
-            Some(dir_path.join(&*s))
-        } else {
-            None
-        }
-    }
-
-    /// Returns a path to a module.
-    pub(super) fn default_submod_path(
-        id: ast::Ident,
-        relative: Option<ast::Ident>,
-        dir_path: &Path,
-        source_map: &SourceMap) -> ModulePath
-    {
-        // If we're in a foo.rs file instead of a mod.rs file,
-        // we need to look for submodules in
-        // `./foo/<id>.rs` and `./foo/<id>/mod.rs` rather than
-        // `./<id>.rs` and `./<id>/mod.rs`.
-        let relative_prefix_string;
-        let relative_prefix = if let Some(ident) = relative {
-            relative_prefix_string = format!("{}{}", ident, path::MAIN_SEPARATOR);
-            &relative_prefix_string
-        } else {
-            ""
-        };
-
-        let mod_name = id.to_string();
-        let default_path_str = format!("{}{}.rs", relative_prefix, mod_name);
-        let secondary_path_str = format!("{}{}{}mod.rs",
-                                         relative_prefix, mod_name, path::MAIN_SEPARATOR);
-        let default_path = dir_path.join(&default_path_str);
-        let secondary_path = dir_path.join(&secondary_path_str);
-        let default_exists = source_map.file_exists(&default_path);
-        let secondary_exists = source_map.file_exists(&secondary_path);
-
-        let result = match (default_exists, secondary_exists) {
-            (true, false) => Ok(ModulePathSuccess {
-                path: default_path,
-                directory_ownership: DirectoryOwnership::Owned {
-                    relative: Some(id),
-                },
-            }),
-            (false, true) => Ok(ModulePathSuccess {
-                path: secondary_path,
-                directory_ownership: DirectoryOwnership::Owned {
-                    relative: None,
-                },
-            }),
-            (false, false) => Err(Error::FileNotFoundForModule {
-                mod_name: mod_name.clone(),
-                default_path: default_path_str,
-                secondary_path: secondary_path_str,
-                dir_path: dir_path.display().to_string(),
-            }),
-            (true, true) => Err(Error::DuplicatePaths {
-                mod_name: mod_name.clone(),
-                default_path: default_path_str,
-                secondary_path: secondary_path_str,
-            }),
-        };
-
-        ModulePath {
-            name: mod_name,
-            path_exists: default_exists || secondary_exists,
-            result,
-        }
-    }
-
-    /// Reads a module from a source file.
-    fn eval_src_mod(
-        &mut self,
-        path: PathBuf,
-        directory_ownership: DirectoryOwnership,
-        name: String,
-        id_sp: Span,
-    ) -> PResult<'a, (Mod, Vec<Attribute>)> {
-        let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
-        if let Some(i) = included_mod_stack.iter().position(|p| *p == path) {
-            let mut err = String::from("circular modules: ");
-            let len = included_mod_stack.len();
-            for p in &included_mod_stack[i.. len] {
-                err.push_str(&p.to_string_lossy());
-                err.push_str(" -> ");
-            }
-            err.push_str(&path.to_string_lossy());
-            return Err(self.span_fatal(id_sp, &err[..]));
-        }
-        included_mod_stack.push(path.clone());
-        drop(included_mod_stack);
-
-        let mut p0 =
-            new_sub_parser_from_file(self.sess, &path, directory_ownership, Some(name), id_sp);
-        p0.cfg_mods = self.cfg_mods;
-        let mod_inner_lo = p0.token.span;
-        let mod_attrs = p0.parse_inner_attributes()?;
-        let mut m0 = p0.parse_mod_items(&token::Eof, mod_inner_lo)?;
-        m0.inline = false;
-        self.sess.included_mod_stack.borrow_mut().pop();
-        Ok((m0, mod_attrs))
-    }
-
-    fn push_directory(&mut self, id: Ident, attrs: &[Attribute]) {
-        if let Some(path) = attr::first_attr_value_str_by_name(attrs, sym::path) {
-            self.directory.path.to_mut().push(&*path.as_str());
-            self.directory.ownership = DirectoryOwnership::Owned { relative: None };
-        } else {
-            // We have to push on the current module name in the case of relative
-            // paths in order to ensure that any additional module paths from inline
-            // `mod x { ... }` come after the relative extension.
-            //
-            // For example, a `mod z { ... }` inside `x/y.rs` should set the current
-            // directory path to `/x/y/z`, not `/x/z` with a relative offset of `y`.
-            if let DirectoryOwnership::Owned { relative } = &mut self.directory.ownership {
-                if let Some(ident) = relative.take() { // remove the relative offset
-                    self.directory.path.to_mut().push(&*ident.as_str());
-                }
-            }
-            self.directory.path.to_mut().push(&*id.as_str());
-        }
-    }
-}
diff --git a/src/libsyntax/parse/parser/pat.rs b/src/libsyntax/parse/parser/pat.rs
deleted file mode 100644
index f347300da71..00000000000
--- a/src/libsyntax/parse/parser/pat.rs
+++ /dev/null
@@ -1,1016 +0,0 @@
-use super::{Parser, PathStyle};
-
-use crate::{maybe_recover_from_interpolated_ty_qpath, maybe_whole};
-use crate::ptr::P;
-use crate::ast::{self, Attribute, Pat, PatKind, FieldPat, RangeEnd, RangeSyntax, Mac};
-use crate::ast::{BindingMode, Ident, Mutability, Path, QSelf, Expr, ExprKind};
-use crate::mut_visit::{noop_visit_pat, noop_visit_mac, MutVisitor};
-use crate::token;
-use crate::print::pprust;
-use crate::source_map::{respan, Span, Spanned};
-use crate::ThinVec;
-use syntax_pos::symbol::{kw, sym};
-use errors::{PResult, Applicability, DiagnosticBuilder};
-
-type Expected = Option<&'static str>;
-
-/// `Expected` for function and lambda parameter patterns.
-pub(super) const PARAM_EXPECTED: Expected = Some("parameter name");
-
-const WHILE_PARSING_OR_MSG: &str = "while parsing this or-pattern starting here";
-
-/// Whether or not an or-pattern should be gated when occurring in the current context.
-#[derive(PartialEq)]
-pub(super) enum GateOr { Yes, No }
-
-/// Whether or not to recover a `,` when parsing or-patterns.
-#[derive(PartialEq, Copy, Clone)]
-enum RecoverComma { Yes, No }
-
-impl<'a> Parser<'a> {
-    /// Parses a pattern.
-    ///
-    /// Corresponds to `pat<no_top_alt>` in RFC 2535 and does not admit or-patterns
-    /// at the top level. Used when parsing the parameters of lambda expressions,
-    /// functions, function pointers, and `pat` macro fragments.
-    pub fn parse_pat(&mut self, expected: Expected) -> PResult<'a, P<Pat>> {
-        self.parse_pat_with_range_pat(true, expected)
-    }
-
-    /// Entry point to the main pattern parser.
-    /// Corresponds to `top_pat` in RFC 2535 and allows or-pattern at the top level.
-    pub(super) fn parse_top_pat(&mut self, gate_or: GateOr) -> PResult<'a, P<Pat>> {
-        // Allow a '|' before the pats (RFCs 1925, 2530, and 2535).
-        let gated_leading_vert = self.eat_or_separator(None) && gate_or == GateOr::Yes;
-        let leading_vert_span = self.prev_span;
-
-        // Parse the possibly-or-pattern.
-        let pat = self.parse_pat_with_or(None, gate_or, RecoverComma::Yes)?;
-
-        // If we parsed a leading `|` which should be gated,
-        // and no other gated or-pattern has been parsed thus far,
-        // then we should really gate the leading `|`.
-        // This complicated procedure is done purely for diagnostics UX.
-        if gated_leading_vert && self.sess.gated_spans.is_ungated(sym::or_patterns) {
-            self.sess.gated_spans.gate(sym::or_patterns, leading_vert_span);
-        }
-
-        Ok(pat)
-    }
-
-    /// Parse the pattern for a function or function pointer parameter.
-    /// Special recovery is provided for or-patterns and leading `|`.
-    pub(super) fn parse_fn_param_pat(&mut self) -> PResult<'a, P<Pat>> {
-        self.recover_leading_vert(None, "not allowed in a parameter pattern");
-        let pat = self.parse_pat_with_or(PARAM_EXPECTED, GateOr::No, RecoverComma::No)?;
-
-        if let PatKind::Or(..) = &pat.kind {
-            self.ban_illegal_fn_param_or_pat(&pat);
-        }
-
-        Ok(pat)
-    }
-
-    /// Ban `A | B` immediately in a parameter pattern and suggest wrapping in parens.
-    fn ban_illegal_fn_param_or_pat(&self, pat: &Pat) {
-        let msg = "wrap the pattern in parenthesis";
-        let fix = format!("({})", pprust::pat_to_string(pat));
-        self.struct_span_err(pat.span, "an or-pattern parameter must be wrapped in parenthesis")
-            .span_suggestion(pat.span, msg, fix, Applicability::MachineApplicable)
-            .emit();
-    }
-
-    /// Parses a pattern, that may be a or-pattern (e.g. `Foo | Bar` in `Some(Foo | Bar)`).
-    /// Corresponds to `pat<allow_top_alt>` in RFC 2535.
-    fn parse_pat_with_or(
-        &mut self,
-        expected: Expected,
-        gate_or: GateOr,
-        rc: RecoverComma,
-    ) -> PResult<'a, P<Pat>> {
-        // Parse the first pattern (`p_0`).
-        let first_pat = self.parse_pat(expected)?;
-        self.maybe_recover_unexpected_comma(first_pat.span, rc)?;
-
-        // If the next token is not a `|`,
-        // this is not an or-pattern and we should exit here.
-        if !self.check(&token::BinOp(token::Or)) && self.token != token::OrOr {
-            return Ok(first_pat)
-        }
-
-        // Parse the patterns `p_1 | ... | p_n` where `n > 0`.
-        let lo = first_pat.span;
-        let mut pats = vec![first_pat];
-        while self.eat_or_separator(Some(lo)) {
-            let pat = self.parse_pat(expected).map_err(|mut err| {
-                err.span_label(lo, WHILE_PARSING_OR_MSG);
-                err
-            })?;
-            self.maybe_recover_unexpected_comma(pat.span, rc)?;
-            pats.push(pat);
-        }
-        let or_pattern_span = lo.to(self.prev_span);
-
-        // Feature gate the or-pattern if instructed:
-        if gate_or == GateOr::Yes {
-            self.sess.gated_spans.gate(sym::or_patterns, or_pattern_span);
-        }
-
-        Ok(self.mk_pat(or_pattern_span, PatKind::Or(pats)))
-    }
-
-    /// Eat the or-pattern `|` separator.
-    /// If instead a `||` token is encountered, recover and pretend we parsed `|`.
-    fn eat_or_separator(&mut self, lo: Option<Span>) -> bool {
-        if self.recover_trailing_vert(lo) {
-            return false;
-        }
-
-        match self.token.kind {
-            token::OrOr => {
-                // Found `||`; Recover and pretend we parsed `|`.
-                self.ban_unexpected_or_or(lo);
-                self.bump();
-                true
-            }
-            _ => self.eat(&token::BinOp(token::Or)),
-        }
-    }
-
-    /// Recover if `|` or `||` is the current token and we have one of the
-    /// tokens `=>`, `if`, `=`, `:`, `;`, `,`, `]`, `)`, or `}` ahead of us.
-    ///
-    /// These tokens all indicate that we reached the end of the or-pattern
-    /// list and can now reliably say that the `|` was an illegal trailing vert.
-    /// Note that there are more tokens such as `@` for which we know that the `|`
-    /// is an illegal parse. However, the user's intent is less clear in that case.
-    fn recover_trailing_vert(&mut self, lo: Option<Span>) -> bool {
-        let is_end_ahead = self.look_ahead(1, |token| match &token.kind {
-            token::FatArrow // e.g. `a | => 0,`.
-            | token::Ident(kw::If, false) // e.g. `a | if expr`.
-            | token::Eq // e.g. `let a | = 0`.
-            | token::Semi // e.g. `let a |;`.
-            | token::Colon // e.g. `let a | :`.
-            | token::Comma // e.g. `let (a |,)`.
-            | token::CloseDelim(token::Bracket) // e.g. `let [a | ]`.
-            | token::CloseDelim(token::Paren) // e.g. `let (a | )`.
-            | token::CloseDelim(token::Brace) => true, // e.g. `let A { f: a | }`.
-            _ => false,
-        });
-        match (is_end_ahead, &self.token.kind) {
-            (true, token::BinOp(token::Or)) | (true, token::OrOr) => {
-                self.ban_illegal_vert(lo, "trailing", "not allowed in an or-pattern");
-                self.bump();
-                true
-            }
-            _ => false,
-        }
-    }
-
-    /// We have parsed `||` instead of `|`. Error and suggest `|` instead.
-    fn ban_unexpected_or_or(&mut self, lo: Option<Span>) {
-        let mut err = self.struct_span_err(self.token.span, "unexpected token `||` after pattern");
-        err.span_suggestion(
-            self.token.span,
-            "use a single `|` to separate multiple alternative patterns",
-            "|".to_owned(),
-            Applicability::MachineApplicable
-        );
-        if let Some(lo) = lo {
-            err.span_label(lo, WHILE_PARSING_OR_MSG);
-        }
-        err.emit();
-    }
-
-    /// Some special error handling for the "top-level" patterns in a match arm,
-    /// `for` loop, `let`, &c. (in contrast to subpatterns within such).
-    fn maybe_recover_unexpected_comma(&mut self, lo: Span, rc: RecoverComma) -> PResult<'a, ()> {
-        if rc == RecoverComma::No || self.token != token::Comma {
-            return Ok(());
-        }
-
-        // An unexpected comma after a top-level pattern is a clue that the
-        // user (perhaps more accustomed to some other language) forgot the
-        // parentheses in what should have been a tuple pattern; return a
-        // suggestion-enhanced error here rather than choking on the comma later.
-        let comma_span = self.token.span;
-        self.bump();
-        if let Err(mut err) = self.skip_pat_list() {
-            // We didn't expect this to work anyway; we just wanted to advance to the
-            // end of the comma-sequence so we know the span to suggest parenthesizing.
-            err.cancel();
-        }
-        let seq_span = lo.to(self.prev_span);
-        let mut err = self.struct_span_err(comma_span, "unexpected `,` in pattern");
-        if let Ok(seq_snippet) = self.span_to_snippet(seq_span) {
-            err.span_suggestion(
-                seq_span,
-                "try adding parentheses to match on a tuple..",
-                format!("({})", seq_snippet),
-                Applicability::MachineApplicable
-            )
-            .span_suggestion(
-                seq_span,
-                "..or a vertical bar to match on multiple alternatives",
-                format!("{}", seq_snippet.replace(",", " |")),
-                Applicability::MachineApplicable
-            );
-        }
-        Err(err)
-    }
-
-    /// Parse and throw away a parentesized comma separated
-    /// sequence of patterns until `)` is reached.
-    fn skip_pat_list(&mut self) -> PResult<'a, ()> {
-        while !self.check(&token::CloseDelim(token::Paren)) {
-            self.parse_pat(None)?;
-            if !self.eat(&token::Comma) {
-                return Ok(())
-            }
-        }
-        Ok(())
-    }
-
-    /// Recursive possibly-or-pattern parser with recovery for an erroneous leading `|`.
-    /// See `parse_pat_with_or` for details on parsing or-patterns.
-    fn parse_pat_with_or_inner(&mut self) -> PResult<'a, P<Pat>> {
-        self.recover_leading_vert(None, "only allowed in a top-level pattern");
-        self.parse_pat_with_or(None, GateOr::Yes, RecoverComma::No)
-    }
-
-    /// Recover if `|` or `||` is here.
-    /// The user is thinking that a leading `|` is allowed in this position.
-    fn recover_leading_vert(&mut self, lo: Option<Span>, ctx: &str) {
-        if let token::BinOp(token::Or) | token::OrOr = self.token.kind {
-            self.ban_illegal_vert(lo, "leading", ctx);
-            self.bump();
-        }
-    }
-
-    /// A `|` or possibly `||` token shouldn't be here. Ban it.
-    fn ban_illegal_vert(&mut self, lo: Option<Span>, pos: &str, ctx: &str) {
-        let span = self.token.span;
-        let mut err = self.struct_span_err(span, &format!("a {} `|` is {}", pos, ctx));
-        err.span_suggestion(
-            span,
-            &format!("remove the `{}`", pprust::token_to_string(&self.token)),
-            String::new(),
-            Applicability::MachineApplicable,
-        );
-        if let Some(lo) = lo {
-            err.span_label(lo, WHILE_PARSING_OR_MSG);
-        }
-        if let token::OrOr = self.token.kind {
-            err.note("alternatives in or-patterns are separated with `|`, not `||`");
-        }
-        err.emit();
-    }
-
-    /// Parses a pattern, with a setting whether modern range patterns (e.g., `a..=b`, `a..b` are
-    /// allowed).
-    fn parse_pat_with_range_pat(
-        &mut self,
-        allow_range_pat: bool,
-        expected: Expected,
-    ) -> PResult<'a, P<Pat>> {
-        maybe_recover_from_interpolated_ty_qpath!(self, true);
-        maybe_whole!(self, NtPat, |x| x);
-
-        let lo = self.token.span;
-        let pat = match self.token.kind {
-            token::BinOp(token::And) | token::AndAnd => self.parse_pat_deref(expected)?,
-            token::OpenDelim(token::Paren) => self.parse_pat_tuple_or_parens()?,
-            token::OpenDelim(token::Bracket) => {
-                // Parse `[pat, pat,...]` as a slice pattern.
-                let (pats, _) = self.parse_delim_comma_seq(
-                    token::Bracket,
-                    |p| p.parse_pat_with_or_inner(),
-                )?;
-                PatKind::Slice(pats)
-            }
-            token::DotDot => {
-                self.bump();
-                if self.is_pat_range_end_start() {
-                    // Parse `..42` for recovery.
-                    self.parse_pat_range_to(RangeEnd::Excluded, "..")?
-                } else {
-                    // A rest pattern `..`.
-                    PatKind::Rest
-                }
-            }
-            token::DotDotEq => {
-                // Parse `..=42` for recovery.
-                self.bump();
-                self.parse_pat_range_to(RangeEnd::Included(RangeSyntax::DotDotEq), "..=")?
-            }
-            token::DotDotDot => {
-                // Parse `...42` for recovery.
-                self.bump();
-                self.parse_pat_range_to(RangeEnd::Included(RangeSyntax::DotDotDot), "...")?
-            }
-            // At this point, token != `&`, `&&`, `(`, `[`, `..`, `..=`, or `...`.
-            _ => if self.eat_keyword(kw::Underscore) {
-                // Parse _
-                PatKind::Wild
-            } else if self.eat_keyword(kw::Mut) {
-                self.parse_pat_ident_mut()?
-            } else if self.eat_keyword(kw::Ref) {
-                // Parse ref ident @ pat / ref mut ident @ pat
-                let mutbl = self.parse_mutability();
-                self.parse_pat_ident(BindingMode::ByRef(mutbl))?
-            } else if self.eat_keyword(kw::Box) {
-                // Parse `box pat`
-                let pat = self.parse_pat_with_range_pat(false, None)?;
-                self.sess.gated_spans.gate(sym::box_patterns, lo.to(self.prev_span));
-                PatKind::Box(pat)
-            } else if self.can_be_ident_pat() {
-                // Parse `ident @ pat`
-                // This can give false positives and parse nullary enums,
-                // they are dealt with later in resolve.
-                self.parse_pat_ident(BindingMode::ByValue(Mutability::Immutable))?
-            } else if self.is_start_of_pat_with_path() {
-                // Parse pattern starting with a path
-                let (qself, path) = if self.eat_lt() {
-                    // Parse a qualified path
-                    let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
-                    (Some(qself), path)
-                } else {
-                    // Parse an unqualified path
-                    (None, self.parse_path(PathStyle::Expr)?)
-                };
-                match self.token.kind {
-                    token::Not if qself.is_none() => self.parse_pat_mac_invoc(lo, path)?,
-                    token::DotDotDot | token::DotDotEq | token::DotDot => {
-                        self.parse_pat_range_starting_with_path(lo, qself, path)?
-                    }
-                    token::OpenDelim(token::Brace) => self.parse_pat_struct(qself, path)?,
-                    token::OpenDelim(token::Paren) => self.parse_pat_tuple_struct(qself, path)?,
-                    _ => PatKind::Path(qself, path),
-                }
-            } else {
-                // Try to parse everything else as literal with optional minus
-                match self.parse_literal_maybe_minus() {
-                    Ok(begin)
-                        if self.check(&token::DotDot)
-                            || self.check(&token::DotDotEq)
-                            || self.check(&token::DotDotDot) =>
-                    {
-                        self.parse_pat_range_starting_with_lit(begin)?
-                    }
-                    Ok(begin) => PatKind::Lit(begin),
-                    Err(err) => return self.fatal_unexpected_non_pat(err, expected),
-                }
-            }
-        };
-
-        let pat = self.mk_pat(lo.to(self.prev_span), pat);
-        let pat = self.maybe_recover_from_bad_qpath(pat, true)?;
-        let pat = self.recover_intersection_pat(pat)?;
-
-        if !allow_range_pat {
-            self.ban_pat_range_if_ambiguous(&pat)?
-        }
-
-        Ok(pat)
-    }
-
-    /// Try to recover the more general form `intersect ::= $pat_lhs @ $pat_rhs`.
-    ///
-    /// Allowed binding patterns generated by `binding ::= ref? mut? $ident @ $pat_rhs`
-    /// should already have been parsed by now  at this point,
-    /// if the next token is `@` then we can try to parse the more general form.
-    ///
-    /// Consult `parse_pat_ident` for the `binding` grammar.
-    ///
-    /// The notion of intersection patterns are found in
-    /// e.g. [F#][and] where they are called AND-patterns.
-    ///
-    /// [and]: https://docs.microsoft.com/en-us/dotnet/fsharp/language-reference/pattern-matching
-    fn recover_intersection_pat(&mut self, lhs: P<Pat>) -> PResult<'a, P<Pat>> {
-        if self.token.kind != token::At {
-            // Next token is not `@` so it's not going to be an intersection pattern.
-            return Ok(lhs);
-        }
-
-        // At this point we attempt to parse `@ $pat_rhs` and emit an error.
-        self.bump(); // `@`
-        let mut rhs = self.parse_pat(None)?;
-        let sp = lhs.span.to(rhs.span);
-
-        if let PatKind::Ident(_, _, ref mut sub @ None) = rhs.kind {
-            // The user inverted the order, so help them fix that.
-            let mut applicability = Applicability::MachineApplicable;
-            lhs.walk(&mut |p| match p.kind {
-                // `check_match` is unhappy if the subpattern has a binding anywhere.
-                PatKind::Ident(..) => {
-                    applicability = Applicability::MaybeIncorrect;
-                    false // Short-circuit.
-                },
-                _ => true,
-            });
-
-            let lhs_span = lhs.span;
-            // Move the LHS into the RHS as a subpattern.
-            // The RHS is now the full pattern.
-            *sub = Some(lhs);
-
-            self.struct_span_err(sp, "pattern on wrong side of `@`")
-                .span_label(lhs_span, "pattern on the left, should be on the right")
-                .span_label(rhs.span, "binding on the right, should be on the left")
-                .span_suggestion(sp, "switch the order", pprust::pat_to_string(&rhs), applicability)
-                .emit();
-        } else {
-            // The special case above doesn't apply so we may have e.g. `A(x) @ B(y)`.
-            rhs.kind = PatKind::Wild;
-            self.struct_span_err(sp, "left-hand side of `@` must be a binding")
-                .span_label(lhs.span, "interpreted as a pattern, not a binding")
-                .span_label(rhs.span, "also a pattern")
-                .note("bindings are `x`, `mut x`, `ref x`, and `ref mut x`")
-                .emit();
-        }
-
-        rhs.span = sp;
-        Ok(rhs)
-    }
-
-    /// Ban a range pattern if it has an ambiguous interpretation.
-    fn ban_pat_range_if_ambiguous(&self, pat: &Pat) -> PResult<'a, ()> {
-        match pat.kind {
-            PatKind::Range(
-                .., Spanned { node: RangeEnd::Included(RangeSyntax::DotDotDot), .. }
-            ) => return Ok(()),
-            PatKind::Range(..) => {}
-            _ => return Ok(()),
-        }
-
-        let mut err = self.struct_span_err(
-            pat.span,
-            "the range pattern here has ambiguous interpretation",
-        );
-        err.span_suggestion(
-            pat.span,
-            "add parentheses to clarify the precedence",
-            format!("({})", pprust::pat_to_string(&pat)),
-            // "ambiguous interpretation" implies that we have to be guessing
-            Applicability::MaybeIncorrect
-        );
-        Err(err)
-    }
-
-    /// Parse `&pat` / `&mut pat`.
-    fn parse_pat_deref(&mut self, expected: Expected) -> PResult<'a, PatKind> {
-        self.expect_and()?;
-        let mutbl = self.parse_mutability();
-
-        if let token::Lifetime(name) = self.token.kind {
-            let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern", name));
-            err.span_label(self.token.span, "unexpected lifetime");
-            return Err(err);
-        }
-
-        let subpat = self.parse_pat_with_range_pat(false, expected)?;
-        Ok(PatKind::Ref(subpat, mutbl))
-    }
-
-    /// Parse a tuple or parenthesis pattern.
-    fn parse_pat_tuple_or_parens(&mut self) -> PResult<'a, PatKind> {
-        let (fields, trailing_comma) = self.parse_paren_comma_seq(|p| p.parse_pat_with_or_inner())?;
-
-        // Here, `(pat,)` is a tuple pattern.
-        // For backward compatibility, `(..)` is a tuple pattern as well.
-        Ok(if fields.len() == 1 && !(trailing_comma || fields[0].is_rest()) {
-            PatKind::Paren(fields.into_iter().nth(0).unwrap())
-        } else {
-            PatKind::Tuple(fields)
-        })
-    }
-
-    /// Parse a mutable binding with the `mut` token already eaten.
-    fn parse_pat_ident_mut(&mut self) -> PResult<'a, PatKind> {
-        let mut_span = self.prev_span;
-
-        if self.eat_keyword(kw::Ref) {
-            return self.recover_mut_ref_ident(mut_span)
-        }
-
-        self.recover_additional_muts();
-
-        // Make sure we don't allow e.g. `let mut $p;` where `$p:pat`.
-        if let token::Interpolated(ref nt) = self.token.kind {
-             if let token::NtPat(_) = **nt {
-                 self.expected_ident_found().emit();
-             }
-        }
-
-        // Parse the pattern we hope to be an identifier.
-        let mut pat = self.parse_pat(Some("identifier"))?;
-
-        // Add `mut` to any binding in the parsed pattern.
-        let changed_any_binding = Self::make_all_value_bindings_mutable(&mut pat);
-
-        // Unwrap; If we don't have `mut $ident`, error.
-        let pat = pat.into_inner();
-        match &pat.kind {
-            PatKind::Ident(..) => {}
-            _ => self.ban_mut_general_pat(mut_span, &pat, changed_any_binding),
-        }
-
-        Ok(pat.kind)
-    }
-
-    /// Recover on `mut ref? ident @ pat` and suggest
-    /// that the order of `mut` and `ref` is incorrect.
-    fn recover_mut_ref_ident(&mut self, lo: Span) -> PResult<'a, PatKind> {
-        let mutref_span = lo.to(self.prev_span);
-        self.struct_span_err(mutref_span, "the order of `mut` and `ref` is incorrect")
-            .span_suggestion(
-                mutref_span,
-                "try switching the order",
-                "ref mut".into(),
-                Applicability::MachineApplicable
-            )
-            .emit();
-
-        self.parse_pat_ident(BindingMode::ByRef(Mutability::Mutable))
-    }
-
-    /// Turn all by-value immutable bindings in a pattern into mutable bindings.
-    /// Returns `true` if any change was made.
-    fn make_all_value_bindings_mutable(pat: &mut P<Pat>) -> bool {
-        struct AddMut(bool);
-        impl MutVisitor for AddMut {
-            fn visit_mac(&mut self, mac: &mut Mac) {
-                noop_visit_mac(mac, self);
-            }
-
-            fn visit_pat(&mut self, pat: &mut P<Pat>) {
-                if let PatKind::Ident(BindingMode::ByValue(ref mut m @ Mutability::Immutable), ..)
-                    = pat.kind
-                {
-                    *m = Mutability::Mutable;
-                    self.0 = true;
-                }
-                noop_visit_pat(pat, self);
-            }
-        }
-
-        let mut add_mut = AddMut(false);
-        add_mut.visit_pat(pat);
-        add_mut.0
-    }
-
-    /// Error on `mut $pat` where `$pat` is not an ident.
-    fn ban_mut_general_pat(&self, lo: Span, pat: &Pat, changed_any_binding: bool) {
-        let span = lo.to(pat.span);
-        let fix = pprust::pat_to_string(&pat);
-        let (problem, suggestion) = if changed_any_binding {
-            ("`mut` must be attached to each individual binding", "add `mut` to each binding")
-        } else {
-            ("`mut` must be followed by a named binding", "remove the `mut` prefix")
-        };
-        self.struct_span_err(span, problem)
-            .span_suggestion(span, suggestion, fix, Applicability::MachineApplicable)
-            .note("`mut` may be followed by `variable` and `variable @ pattern`")
-            .emit()
-    }
-
-    /// Eat any extraneous `mut`s and error + recover if we ate any.
-    fn recover_additional_muts(&mut self) {
-        let lo = self.token.span;
-        while self.eat_keyword(kw::Mut) {}
-        if lo == self.token.span {
-            return;
-        }
-
-        let span = lo.to(self.prev_span);
-        self.struct_span_err(span, "`mut` on a binding may not be repeated")
-            .span_suggestion(
-                span,
-                "remove the additional `mut`s",
-                String::new(),
-                Applicability::MachineApplicable,
-            )
-            .emit();
-    }
-
-    /// Parse macro invocation
-    fn parse_pat_mac_invoc(&mut self, lo: Span, path: Path) -> PResult<'a, PatKind> {
-        self.bump();
-        let (delim, tts) = self.expect_delimited_token_tree()?;
-        let mac = Mac {
-            path,
-            tts,
-            delim,
-            span: lo.to(self.prev_span),
-            prior_type_ascription: self.last_type_ascription,
-        };
-        Ok(PatKind::Mac(mac))
-    }
-
-    fn excluded_range_end(&self, span: Span) -> RangeEnd {
-        self.sess.gated_spans.gate(sym::exclusive_range_pattern, span);
-        RangeEnd::Excluded
-    }
-
-    /// Parse a range pattern `$path $form $end?` where `$form = ".." | "..." | "..=" ;`.
-    /// The `$path` has already been parsed and the next token is the `$form`.
-    fn parse_pat_range_starting_with_path(
-        &mut self,
-        lo: Span,
-        qself: Option<QSelf>,
-        path: Path
-    ) -> PResult<'a, PatKind> {
-        let (end_kind, form) = match self.token.kind {
-            token::DotDot => (self.excluded_range_end(self.token.span), ".."),
-            token::DotDotDot => (RangeEnd::Included(RangeSyntax::DotDotDot), "..."),
-            token::DotDotEq => (RangeEnd::Included(RangeSyntax::DotDotEq), "..="),
-            _ => panic!("can only parse `..`/`...`/`..=` for ranges (checked above)"),
-        };
-        let op_span = self.token.span;
-        // Parse range
-        let span = lo.to(self.prev_span);
-        let begin = self.mk_expr(span, ExprKind::Path(qself, path), ThinVec::new());
-        self.bump();
-        let end = self.parse_pat_range_end_opt(&begin, form)?;
-        Ok(PatKind::Range(begin, end, respan(op_span, end_kind)))
-    }
-
-    /// Parse a range pattern `$literal $form $end?` where `$form = ".." | "..." | "..=" ;`.
-    /// The `$path` has already been parsed and the next token is the `$form`.
-    fn parse_pat_range_starting_with_lit(&mut self, begin: P<Expr>) -> PResult<'a, PatKind> {
-        let op_span = self.token.span;
-        let (end_kind, form) = if self.eat(&token::DotDotDot) {
-            (RangeEnd::Included(RangeSyntax::DotDotDot), "...")
-        } else if self.eat(&token::DotDotEq) {
-            (RangeEnd::Included(RangeSyntax::DotDotEq), "..=")
-        } else if self.eat(&token::DotDot) {
-            (self.excluded_range_end(op_span), "..")
-        } else {
-            panic!("impossible case: we already matched on a range-operator token")
-        };
-        let end = self.parse_pat_range_end_opt(&begin, form)?;
-        Ok(PatKind::Range(begin, end, respan(op_span, end_kind)))
-    }
-
-    fn fatal_unexpected_non_pat(
-        &mut self,
-        mut err: DiagnosticBuilder<'a>,
-        expected: Expected,
-    ) -> PResult<'a, P<Pat>> {
-        err.cancel();
-
-        let expected = expected.unwrap_or("pattern");
-        let msg = format!("expected {}, found {}", expected, self.this_token_descr());
-
-        let mut err = self.fatal(&msg);
-        err.span_label(self.token.span, format!("expected {}", expected));
-
-        let sp = self.sess.source_map().start_point(self.token.span);
-        if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow().get(&sp) {
-            self.sess.expr_parentheses_needed(&mut err, *sp, None);
-        }
-
-        Err(err)
-    }
-
-    /// Is the current token suitable as the start of a range patterns end?
-    fn is_pat_range_end_start(&self) -> bool {
-        self.token.is_path_start() // e.g. `MY_CONST`;
-            || self.token == token::Dot // e.g. `.5` for recovery;
-            || self.token.can_begin_literal_or_bool() // e.g. `42`.
-            || self.token.is_whole_expr()
-    }
-
-    /// Parse a range-to pattern, e.g. `..X` and `..=X` for recovery.
-    fn parse_pat_range_to(&mut self, re: RangeEnd, form: &str) -> PResult<'a, PatKind> {
-        let lo = self.prev_span;
-        let end = self.parse_pat_range_end()?;
-        let range_span = lo.to(end.span);
-        let begin = self.mk_expr(range_span, ExprKind::Err, ThinVec::new());
-
-        self.diagnostic()
-            .struct_span_err(range_span, &format!("`{}X` range patterns are not supported", form))
-            .span_suggestion(
-                range_span,
-                "try using the minimum value for the type",
-                format!("MIN{}{}", form, pprust::expr_to_string(&end)),
-                Applicability::HasPlaceholders,
-            )
-            .emit();
-
-        Ok(PatKind::Range(begin, end, respan(lo, re)))
-    }
-
-    /// Parse the end of a `X..Y`, `X..=Y`, or `X...Y` range pattern  or recover
-    /// if that end is missing treating it as `X..`, `X..=`, or `X...` respectively.
-    fn parse_pat_range_end_opt(&mut self, begin: &Expr, form: &str) -> PResult<'a, P<Expr>> {
-        if self.is_pat_range_end_start() {
-            // Parsing e.g. `X..=Y`.
-            self.parse_pat_range_end()
-        } else {
-            // Parsing e.g. `X..`.
-            let range_span = begin.span.to(self.prev_span);
-
-            self.diagnostic()
-                .struct_span_err(
-                    range_span,
-                    &format!("`X{}` range patterns are not supported", form),
-                )
-                .span_suggestion(
-                    range_span,
-                    "try using the maximum value for the type",
-                    format!("{}{}MAX", pprust::expr_to_string(&begin), form),
-                    Applicability::HasPlaceholders,
-                )
-                .emit();
-
-            Ok(self.mk_expr(range_span, ExprKind::Err, ThinVec::new()))
-        }
-    }
-
-    fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
-        if self.token.is_path_start() {
-            let lo = self.token.span;
-            let (qself, path) = if self.eat_lt() {
-                // Parse a qualified path
-                let (qself, path) = self.parse_qpath(PathStyle::Expr)?;
-                (Some(qself), path)
-            } else {
-                // Parse an unqualified path
-                (None, self.parse_path(PathStyle::Expr)?)
-            };
-            let hi = self.prev_span;
-            Ok(self.mk_expr(lo.to(hi), ExprKind::Path(qself, path), ThinVec::new()))
-        } else {
-            self.parse_literal_maybe_minus()
-        }
-    }
-
-    /// Is this the start of a pattern beginning with a path?
-    fn is_start_of_pat_with_path(&mut self) -> bool {
-        self.check_path()
-        // Just for recovery (see `can_be_ident`).
-        || self.token.is_ident() && !self.token.is_bool_lit() && !self.token.is_keyword(kw::In)
-    }
-
-    /// Would `parse_pat_ident` be appropriate here?
-    fn can_be_ident_pat(&mut self) -> bool {
-        self.check_ident()
-        && !self.token.is_bool_lit() // Avoid `true` or `false` as a binding as it is a literal.
-        && !self.token.is_path_segment_keyword() // Avoid e.g. `Self` as it is a path.
-        // Avoid `in`. Due to recovery in the list parser this messes with `for ( $pat in $expr )`.
-        && !self.token.is_keyword(kw::In)
-        && self.look_ahead(1, |t| match t.kind { // Try to do something more complex?
-            token::OpenDelim(token::Paren) // A tuple struct pattern.
-            | token::OpenDelim(token::Brace) // A struct pattern.
-            | token::DotDotDot | token::DotDotEq | token::DotDot // A range pattern.
-            | token::ModSep // A tuple / struct variant pattern.
-            | token::Not => false, // A macro expanding to a pattern.
-            _ => true,
-        })
-    }
-
-    /// Parses `ident` or `ident @ pat`.
-    /// Used by the copy foo and ref foo patterns to give a good
-    /// error message when parsing mistakes like `ref foo(a, b)`.
-    fn parse_pat_ident(&mut self, binding_mode: BindingMode) -> PResult<'a, PatKind> {
-        let ident = self.parse_ident()?;
-        let sub = if self.eat(&token::At) {
-            Some(self.parse_pat(Some("binding pattern"))?)
-        } else {
-            None
-        };
-
-        // Just to be friendly, if they write something like `ref Some(i)`,
-        // we end up here with `(` as the current token.
-        // This shortly leads to a parse error. Note that if there is no explicit
-        // binding mode then we do not end up here, because the lookahead
-        // will direct us over to `parse_enum_variant()`.
-        if self.token == token::OpenDelim(token::Paren) {
-            return Err(self.span_fatal(
-                self.prev_span,
-                "expected identifier, found enum pattern",
-            ))
-        }
-
-        Ok(PatKind::Ident(binding_mode, ident, sub))
-    }
-
-    /// Parse a struct ("record") pattern (e.g. `Foo { ... }` or `Foo::Bar { ... }`).
-    fn parse_pat_struct(&mut self, qself: Option<QSelf>, path: Path) -> PResult<'a, PatKind> {
-        if qself.is_some() {
-            let msg = "unexpected `{` after qualified path";
-            let mut err = self.fatal(msg);
-            err.span_label(self.token.span, msg);
-            return Err(err);
-        }
-
-        self.bump();
-        let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
-            e.emit();
-            self.recover_stmt();
-            (vec![], true)
-        });
-        self.bump();
-        Ok(PatKind::Struct(path, fields, etc))
-    }
-
-    /// Parse tuple struct or tuple variant pattern (e.g. `Foo(...)` or `Foo::Bar(...)`).
-    fn parse_pat_tuple_struct(&mut self, qself: Option<QSelf>, path: Path) -> PResult<'a, PatKind> {
-        if qself.is_some() {
-            let msg = "unexpected `(` after qualified path";
-            let mut err = self.fatal(msg);
-            err.span_label(self.token.span, msg);
-            return Err(err);
-        }
-        let (fields, _) = self.parse_paren_comma_seq(|p| p.parse_pat_with_or_inner())?;
-        Ok(PatKind::TupleStruct(path, fields))
-    }
-
-    /// Parses the fields of a struct-like pattern.
-    fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<FieldPat>, bool)> {
-        let mut fields = Vec::new();
-        let mut etc = false;
-        let mut ate_comma = true;
-        let mut delayed_err: Option<DiagnosticBuilder<'a>> = None;
-        let mut etc_span = None;
-
-        while self.token != token::CloseDelim(token::Brace) {
-            let attrs = match self.parse_outer_attributes() {
-                Ok(attrs) => attrs,
-                Err(err) => {
-                    if let Some(mut delayed) = delayed_err {
-                        delayed.emit();
-                    }
-                    return Err(err);
-                },
-            };
-            let lo = self.token.span;
-
-            // check that a comma comes after every field
-            if !ate_comma {
-                let err = self.struct_span_err(self.prev_span, "expected `,`");
-                if let Some(mut delayed) = delayed_err {
-                    delayed.emit();
-                }
-                return Err(err);
-            }
-            ate_comma = false;
-
-            if self.check(&token::DotDot) || self.token == token::DotDotDot {
-                etc = true;
-                let mut etc_sp = self.token.span;
-
-                self.recover_one_fewer_dotdot();
-                self.bump();  // `..` || `...`
-
-                if self.token == token::CloseDelim(token::Brace) {
-                    etc_span = Some(etc_sp);
-                    break;
-                }
-                let token_str = self.this_token_descr();
-                let mut err = self.fatal(&format!("expected `}}`, found {}", token_str));
-
-                err.span_label(self.token.span, "expected `}`");
-                let mut comma_sp = None;
-                if self.token == token::Comma { // Issue #49257
-                    let nw_span = self.sess.source_map().span_until_non_whitespace(self.token.span);
-                    etc_sp = etc_sp.to(nw_span);
-                    err.span_label(etc_sp,
-                                   "`..` must be at the end and cannot have a trailing comma");
-                    comma_sp = Some(self.token.span);
-                    self.bump();
-                    ate_comma = true;
-                }
-
-                etc_span = Some(etc_sp.until(self.token.span));
-                if self.token == token::CloseDelim(token::Brace) {
-                    // If the struct looks otherwise well formed, recover and continue.
-                    if let Some(sp) = comma_sp {
-                        err.span_suggestion_short(
-                            sp,
-                            "remove this comma",
-                            String::new(),
-                            Applicability::MachineApplicable,
-                        );
-                    }
-                    err.emit();
-                    break;
-                } else if self.token.is_ident() && ate_comma {
-                    // Accept fields coming after `..,`.
-                    // This way we avoid "pattern missing fields" errors afterwards.
-                    // We delay this error until the end in order to have a span for a
-                    // suggested fix.
-                    if let Some(mut delayed_err) = delayed_err {
-                        delayed_err.emit();
-                        return Err(err);
-                    } else {
-                        delayed_err = Some(err);
-                    }
-                } else {
-                    if let Some(mut err) = delayed_err {
-                        err.emit();
-                    }
-                    return Err(err);
-                }
-            }
-
-            fields.push(match self.parse_pat_field(lo, attrs) {
-                Ok(field) => field,
-                Err(err) => {
-                    if let Some(mut delayed_err) = delayed_err {
-                        delayed_err.emit();
-                    }
-                    return Err(err);
-                }
-            });
-            ate_comma = self.eat(&token::Comma);
-        }
-
-        if let Some(mut err) = delayed_err {
-            if let Some(etc_span) = etc_span {
-                err.multipart_suggestion(
-                    "move the `..` to the end of the field list",
-                    vec![
-                        (etc_span, String::new()),
-                        (self.token.span, format!("{}.. }}", if ate_comma { "" } else { ", " })),
-                    ],
-                    Applicability::MachineApplicable,
-                );
-            }
-            err.emit();
-        }
-        return Ok((fields, etc));
-    }
-
-    /// Recover on `...` as if it were `..` to avoid further errors.
-    /// See issue #46718.
-    fn recover_one_fewer_dotdot(&self) {
-        if self.token != token::DotDotDot {
-            return;
-        }
-
-        self.struct_span_err(self.token.span, "expected field pattern, found `...`")
-            .span_suggestion(
-                self.token.span,
-                "to omit remaining fields, use one fewer `.`",
-                "..".to_owned(),
-                Applicability::MachineApplicable
-            )
-            .emit();
-    }
-
-    fn parse_pat_field(&mut self, lo: Span, attrs: Vec<Attribute>) -> PResult<'a, FieldPat> {
-        // Check if a colon exists one ahead. This means we're parsing a fieldname.
-        let hi;
-        let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
-            // Parsing a pattern of the form `fieldname: pat`.
-            let fieldname = self.parse_field_name()?;
-            self.bump();
-            let pat = self.parse_pat_with_or_inner()?;
-            hi = pat.span;
-            (pat, fieldname, false)
-        } else {
-            // Parsing a pattern of the form `(box) (ref) (mut) fieldname`.
-            let is_box = self.eat_keyword(kw::Box);
-            let boxed_span = self.token.span;
-            let is_ref = self.eat_keyword(kw::Ref);
-            let is_mut = self.eat_keyword(kw::Mut);
-            let fieldname = self.parse_ident()?;
-            hi = self.prev_span;
-
-            let bind_type = match (is_ref, is_mut) {
-                (true, true) => BindingMode::ByRef(Mutability::Mutable),
-                (true, false) => BindingMode::ByRef(Mutability::Immutable),
-                (false, true) => BindingMode::ByValue(Mutability::Mutable),
-                (false, false) => BindingMode::ByValue(Mutability::Immutable),
-            };
-
-            let fieldpat = self.mk_pat_ident(boxed_span.to(hi), bind_type, fieldname);
-            let subpat = if is_box {
-                self.mk_pat(lo.to(hi), PatKind::Box(fieldpat))
-            } else {
-                fieldpat
-            };
-            (subpat, fieldname, true)
-        };
-
-        Ok(FieldPat {
-            ident: fieldname,
-            pat: subpat,
-            is_shorthand,
-            attrs: attrs.into(),
-            id: ast::DUMMY_NODE_ID,
-            span: lo.to(hi),
-            is_placeholder: false,
-        })
-    }
-
-    pub(super) fn mk_pat_ident(&self, span: Span, bm: BindingMode, ident: Ident) -> P<Pat> {
-        self.mk_pat(span, PatKind::Ident(bm, ident, None))
-    }
-
-    fn mk_pat(&self, span: Span, kind: PatKind) -> P<Pat> {
-        P(Pat { kind, span, id: ast::DUMMY_NODE_ID })
-    }
-}
diff --git a/src/libsyntax/parse/parser/path.rs b/src/libsyntax/parse/parser/path.rs
deleted file mode 100644
index 9ceb3ba1eb4..00000000000
--- a/src/libsyntax/parse/parser/path.rs
+++ /dev/null
@@ -1,497 +0,0 @@
-use super::{Parser, TokenType};
-
-use crate::{maybe_whole, ThinVec};
-use crate::ast::{self, QSelf, Path, PathSegment, Ident, ParenthesizedArgs, AngleBracketedArgs};
-use crate::ast::{AnonConst, GenericArg, AssocTyConstraint, AssocTyConstraintKind, BlockCheckMode};
-use crate::token::{self, Token};
-use crate::source_map::{Span, BytePos};
-use syntax_pos::symbol::{kw, sym};
-
-use std::mem;
-use log::debug;
-use errors::{PResult, Applicability, pluralize};
-
-/// Specifies how to parse a path.
-#[derive(Copy, Clone, PartialEq)]
-pub enum PathStyle {
-    /// In some contexts, notably in expressions, paths with generic arguments are ambiguous
-    /// with something else. For example, in expressions `segment < ....` can be interpreted
-    /// as a comparison and `segment ( ....` can be interpreted as a function call.
-    /// In all such contexts the non-path interpretation is preferred by default for practical
-    /// reasons, but the path interpretation can be forced by the disambiguator `::`, e.g.
-    /// `x<y>` - comparisons, `x::<y>` - unambiguously a path.
-    Expr,
-    /// In other contexts, notably in types, no ambiguity exists and paths can be written
-    /// without the disambiguator, e.g., `x<y>` - unambiguously a path.
-    /// Paths with disambiguators are still accepted, `x::<Y>` - unambiguously a path too.
-    Type,
-    /// A path with generic arguments disallowed, e.g., `foo::bar::Baz`, used in imports,
-    /// visibilities or attributes.
-    /// Technically, this variant is unnecessary and e.g., `Expr` can be used instead
-    /// (paths in "mod" contexts have to be checked later for absence of generic arguments
-    /// anyway, due to macros), but it is used to avoid weird suggestions about expected
-    /// tokens when something goes wrong.
-    Mod,
-}
-
-impl<'a> Parser<'a> {
-    /// Parses a qualified path.
-    /// Assumes that the leading `<` has been parsed already.
-    ///
-    /// `qualified_path = <type [as trait_ref]>::path`
-    ///
-    /// # Examples
-    /// `<T>::default`
-    /// `<T as U>::a`
-    /// `<T as U>::F::a<S>` (without disambiguator)
-    /// `<T as U>::F::a::<S>` (with disambiguator)
-    pub(super) fn parse_qpath(&mut self, style: PathStyle) -> PResult<'a, (QSelf, Path)> {
-        let lo = self.prev_span;
-        let ty = self.parse_ty()?;
-
-        // `path` will contain the prefix of the path up to the `>`,
-        // if any (e.g., `U` in the `<T as U>::*` examples
-        // above). `path_span` has the span of that path, or an empty
-        // span in the case of something like `<T>::Bar`.
-        let (mut path, path_span);
-        if self.eat_keyword(kw::As) {
-            let path_lo = self.token.span;
-            path = self.parse_path(PathStyle::Type)?;
-            path_span = path_lo.to(self.prev_span);
-        } else {
-            path_span = self.token.span.to(self.token.span);
-            path = ast::Path { segments: Vec::new(), span: path_span };
-        }
-
-        // See doc comment for `unmatched_angle_bracket_count`.
-        self.expect(&token::Gt)?;
-        if self.unmatched_angle_bracket_count > 0 {
-            self.unmatched_angle_bracket_count -= 1;
-            debug!("parse_qpath: (decrement) count={:?}", self.unmatched_angle_bracket_count);
-        }
-
-        self.expect(&token::ModSep)?;
-
-        let qself = QSelf { ty, path_span, position: path.segments.len() };
-        self.parse_path_segments(&mut path.segments, style)?;
-
-        Ok((qself, Path { segments: path.segments, span: lo.to(self.prev_span) }))
-    }
-
-    /// Parses simple paths.
-    ///
-    /// `path = [::] segment+`
-    /// `segment = ident | ident[::]<args> | ident[::](args) [-> type]`
-    ///
-    /// # Examples
-    /// `a::b::C<D>` (without disambiguator)
-    /// `a::b::C::<D>` (with disambiguator)
-    /// `Fn(Args)` (without disambiguator)
-    /// `Fn::(Args)` (with disambiguator)
-    pub fn parse_path(&mut self, style: PathStyle) -> PResult<'a, Path> {
-        maybe_whole!(self, NtPath, |path| {
-            if style == PathStyle::Mod &&
-               path.segments.iter().any(|segment| segment.args.is_some()) {
-                self.diagnostic().span_err(path.span, "unexpected generic arguments in path");
-            }
-            path
-        });
-
-        let lo = self.meta_var_span.unwrap_or(self.token.span);
-        let mut segments = Vec::new();
-        let mod_sep_ctxt = self.token.span.ctxt();
-        if self.eat(&token::ModSep) {
-            segments.push(PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt)));
-        }
-        self.parse_path_segments(&mut segments, style)?;
-
-        Ok(Path { segments, span: lo.to(self.prev_span) })
-    }
-
-    /// Like `parse_path`, but also supports parsing `Word` meta items into paths for
-    /// backwards-compatibility. This is used when parsing derive macro paths in `#[derive]`
-    /// attributes.
-    fn parse_path_allowing_meta(&mut self, style: PathStyle) -> PResult<'a, Path> {
-        let meta_ident = match self.token.kind {
-            token::Interpolated(ref nt) => match **nt {
-                token::NtMeta(ref item) => match item.tokens.is_empty() {
-                    true => Some(item.path.clone()),
-                    false => None,
-                },
-                _ => None,
-            },
-            _ => None,
-        };
-        if let Some(path) = meta_ident {
-            self.bump();
-            return Ok(path);
-        }
-        self.parse_path(style)
-    }
-
-    /// Parse a list of paths inside `#[derive(path_0, ..., path_n)]`.
-    pub fn parse_derive_paths(&mut self) -> PResult<'a, Vec<Path>> {
-        self.expect(&token::OpenDelim(token::Paren))?;
-        let mut list = Vec::new();
-        while !self.eat(&token::CloseDelim(token::Paren)) {
-            let path = self.parse_path_allowing_meta(PathStyle::Mod)?;
-            list.push(path);
-            if !self.eat(&token::Comma) {
-                self.expect(&token::CloseDelim(token::Paren))?;
-                break
-            }
-        }
-        Ok(list)
-    }
-
-    pub(super) fn parse_path_segments(
-        &mut self,
-        segments: &mut Vec<PathSegment>,
-        style: PathStyle,
-    ) -> PResult<'a, ()> {
-        loop {
-            let segment = self.parse_path_segment(style)?;
-            if style == PathStyle::Expr {
-                // In order to check for trailing angle brackets, we must have finished
-                // recursing (`parse_path_segment` can indirectly call this function),
-                // that is, the next token must be the highlighted part of the below example:
-                //
-                // `Foo::<Bar as Baz<T>>::Qux`
-                //                      ^ here
-                //
-                // As opposed to the below highlight (if we had only finished the first
-                // recursion):
-                //
-                // `Foo::<Bar as Baz<T>>::Qux`
-                //                     ^ here
-                //
-                // `PathStyle::Expr` is only provided at the root invocation and never in
-                // `parse_path_segment` to recurse and therefore can be checked to maintain
-                // this invariant.
-                self.check_trailing_angle_brackets(&segment, token::ModSep);
-            }
-            segments.push(segment);
-
-            if self.is_import_coupler() || !self.eat(&token::ModSep) {
-                return Ok(());
-            }
-        }
-    }
-
-    pub(super) fn parse_path_segment(&mut self, style: PathStyle) -> PResult<'a, PathSegment> {
-        let ident = self.parse_path_segment_ident()?;
-
-        let is_args_start = |token: &Token| match token.kind {
-            token::Lt | token::BinOp(token::Shl) | token::OpenDelim(token::Paren)
-            | token::LArrow => true,
-            _ => false,
-        };
-        let check_args_start = |this: &mut Self| {
-            this.expected_tokens.extend_from_slice(
-                &[TokenType::Token(token::Lt), TokenType::Token(token::OpenDelim(token::Paren))]
-            );
-            is_args_start(&this.token)
-        };
-
-        Ok(if style == PathStyle::Type && check_args_start(self) ||
-              style != PathStyle::Mod && self.check(&token::ModSep)
-                                      && self.look_ahead(1, |t| is_args_start(t)) {
-            // We use `style == PathStyle::Expr` to check if this is in a recursion or not. If
-            // it isn't, then we reset the unmatched angle bracket count as we're about to start
-            // parsing a new path.
-            if style == PathStyle::Expr {
-                self.unmatched_angle_bracket_count = 0;
-                self.max_angle_bracket_count = 0;
-            }
-
-            // Generic arguments are found - `<`, `(`, `::<` or `::(`.
-            self.eat(&token::ModSep);
-            let lo = self.token.span;
-            let args = if self.eat_lt() {
-                // `<'a, T, A = U>`
-                let (args, constraints) =
-                    self.parse_generic_args_with_leaning_angle_bracket_recovery(style, lo)?;
-                self.expect_gt()?;
-                let span = lo.to(self.prev_span);
-                AngleBracketedArgs { args, constraints, span }.into()
-            } else {
-                // `(T, U) -> R`
-                let (inputs, _) = self.parse_paren_comma_seq(|p| p.parse_ty())?;
-                let span = ident.span.to(self.prev_span);
-                let output = if self.eat(&token::RArrow) {
-                    Some(self.parse_ty_common(false, false, false)?)
-                } else {
-                    None
-                };
-                ParenthesizedArgs { inputs, output, span }.into()
-            };
-
-            PathSegment { ident, args, id: ast::DUMMY_NODE_ID }
-        } else {
-            // Generic arguments are not found.
-            PathSegment::from_ident(ident)
-        })
-    }
-
-    pub(super) fn parse_path_segment_ident(&mut self) -> PResult<'a, Ident> {
-        match self.token.kind {
-            token::Ident(name, _) if name.is_path_segment_keyword() => {
-                let span = self.token.span;
-                self.bump();
-                Ok(Ident::new(name, span))
-            }
-            _ => self.parse_ident(),
-        }
-    }
-
-    /// Parses generic args (within a path segment) with recovery for extra leading angle brackets.
-    /// For the purposes of understanding the parsing logic of generic arguments, this function
-    /// can be thought of being the same as just calling `self.parse_generic_args()` if the source
-    /// had the correct amount of leading angle brackets.
-    ///
-    /// ```ignore (diagnostics)
-    /// bar::<<<<T as Foo>::Output>();
-    ///      ^^ help: remove extra angle brackets
-    /// ```
-    fn parse_generic_args_with_leaning_angle_bracket_recovery(
-        &mut self,
-        style: PathStyle,
-        lo: Span,
-    ) -> PResult<'a, (Vec<GenericArg>, Vec<AssocTyConstraint>)> {
-        // We need to detect whether there are extra leading left angle brackets and produce an
-        // appropriate error and suggestion. This cannot be implemented by looking ahead at
-        // upcoming tokens for a matching `>` character - if there are unmatched `<` tokens
-        // then there won't be matching `>` tokens to find.
-        //
-        // To explain how this detection works, consider the following example:
-        //
-        // ```ignore (diagnostics)
-        // bar::<<<<T as Foo>::Output>();
-        //      ^^ help: remove extra angle brackets
-        // ```
-        //
-        // Parsing of the left angle brackets starts in this function. We start by parsing the
-        // `<` token (incrementing the counter of unmatched angle brackets on `Parser` via
-        // `eat_lt`):
-        //
-        // *Upcoming tokens:* `<<<<T as Foo>::Output>;`
-        // *Unmatched count:* 1
-        // *`parse_path_segment` calls deep:* 0
-        //
-        // This has the effect of recursing as this function is called if a `<` character
-        // is found within the expected generic arguments:
-        //
-        // *Upcoming tokens:* `<<<T as Foo>::Output>;`
-        // *Unmatched count:* 2
-        // *`parse_path_segment` calls deep:* 1
-        //
-        // Eventually we will have recursed until having consumed all of the `<` tokens and
-        // this will be reflected in the count:
-        //
-        // *Upcoming tokens:* `T as Foo>::Output>;`
-        // *Unmatched count:* 4
-        // `parse_path_segment` calls deep:* 3
-        //
-        // The parser will continue until reaching the first `>` - this will decrement the
-        // unmatched angle bracket count and return to the parent invocation of this function
-        // having succeeded in parsing:
-        //
-        // *Upcoming tokens:* `::Output>;`
-        // *Unmatched count:* 3
-        // *`parse_path_segment` calls deep:* 2
-        //
-        // This will continue until the next `>` character which will also return successfully
-        // to the parent invocation of this function and decrement the count:
-        //
-        // *Upcoming tokens:* `;`
-        // *Unmatched count:* 2
-        // *`parse_path_segment` calls deep:* 1
-        //
-        // At this point, this function will expect to find another matching `>` character but
-        // won't be able to and will return an error. This will continue all the way up the
-        // call stack until the first invocation:
-        //
-        // *Upcoming tokens:* `;`
-        // *Unmatched count:* 2
-        // *`parse_path_segment` calls deep:* 0
-        //
-        // In doing this, we have managed to work out how many unmatched leading left angle
-        // brackets there are, but we cannot recover as the unmatched angle brackets have
-        // already been consumed. To remedy this, we keep a snapshot of the parser state
-        // before we do the above. We can then inspect whether we ended up with a parsing error
-        // and unmatched left angle brackets and if so, restore the parser state before we
-        // consumed any `<` characters to emit an error and consume the erroneous tokens to
-        // recover by attempting to parse again.
-        //
-        // In practice, the recursion of this function is indirect and there will be other
-        // locations that consume some `<` characters - as long as we update the count when
-        // this happens, it isn't an issue.
-
-        let is_first_invocation = style == PathStyle::Expr;
-        // Take a snapshot before attempting to parse - we can restore this later.
-        let snapshot = if is_first_invocation {
-            Some(self.clone())
-        } else {
-            None
-        };
-
-        debug!("parse_generic_args_with_leading_angle_bracket_recovery: (snapshotting)");
-        match self.parse_generic_args() {
-            Ok(value) => Ok(value),
-            Err(ref mut e) if is_first_invocation && self.unmatched_angle_bracket_count > 0 => {
-                // Cancel error from being unable to find `>`. We know the error
-                // must have been this due to a non-zero unmatched angle bracket
-                // count.
-                e.cancel();
-
-                // Swap `self` with our backup of the parser state before attempting to parse
-                // generic arguments.
-                let snapshot = mem::replace(self, snapshot.unwrap());
-
-                debug!(
-                    "parse_generic_args_with_leading_angle_bracket_recovery: (snapshot failure) \
-                     snapshot.count={:?}",
-                    snapshot.unmatched_angle_bracket_count,
-                );
-
-                // Eat the unmatched angle brackets.
-                for _ in 0..snapshot.unmatched_angle_bracket_count {
-                    self.eat_lt();
-                }
-
-                // Make a span over ${unmatched angle bracket count} characters.
-                let span = lo.with_hi(
-                    lo.lo() + BytePos(snapshot.unmatched_angle_bracket_count)
-                );
-                self.diagnostic()
-                    .struct_span_err(
-                        span,
-                        &format!(
-                            "unmatched angle bracket{}",
-                            pluralize!(snapshot.unmatched_angle_bracket_count)
-                        ),
-                    )
-                    .span_suggestion(
-                        span,
-                        &format!(
-                            "remove extra angle bracket{}",
-                            pluralize!(snapshot.unmatched_angle_bracket_count)
-                        ),
-                        String::new(),
-                        Applicability::MachineApplicable,
-                    )
-                    .emit();
-
-                // Try again without unmatched angle bracket characters.
-                self.parse_generic_args()
-            },
-            Err(e) => Err(e),
-        }
-    }
-
-    /// Parses (possibly empty) list of lifetime and type arguments and associated type bindings,
-    /// possibly including trailing comma.
-    fn parse_generic_args(&mut self) -> PResult<'a, (Vec<GenericArg>, Vec<AssocTyConstraint>)> {
-        let mut args = Vec::new();
-        let mut constraints = Vec::new();
-        let mut misplaced_assoc_ty_constraints: Vec<Span> = Vec::new();
-        let mut assoc_ty_constraints: Vec<Span> = Vec::new();
-
-        let args_lo = self.token.span;
-
-        loop {
-            if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
-                // Parse lifetime argument.
-                args.push(GenericArg::Lifetime(self.expect_lifetime()));
-                misplaced_assoc_ty_constraints.append(&mut assoc_ty_constraints);
-            } else if self.check_ident()
-                && self.look_ahead(1, |t| t == &token::Eq || t == &token::Colon)
-            {
-                // Parse associated type constraint.
-                let lo = self.token.span;
-                let ident = self.parse_ident()?;
-                let kind = if self.eat(&token::Eq) {
-                    AssocTyConstraintKind::Equality {
-                        ty: self.parse_ty()?,
-                    }
-                } else if self.eat(&token::Colon) {
-                    AssocTyConstraintKind::Bound {
-                        bounds: self.parse_generic_bounds(Some(self.prev_span))?,
-                    }
-                } else {
-                    unreachable!();
-                };
-
-                let span = lo.to(self.prev_span);
-
-                // Gate associated type bounds, e.g., `Iterator<Item: Ord>`.
-                if let AssocTyConstraintKind::Bound { .. } = kind {
-                    self.sess.gated_spans.gate(sym::associated_type_bounds, span);
-                }
-
-                constraints.push(AssocTyConstraint {
-                    id: ast::DUMMY_NODE_ID,
-                    ident,
-                    kind,
-                    span,
-                });
-                assoc_ty_constraints.push(span);
-            } else if self.check_const_arg() {
-                // Parse const argument.
-                let expr = if let token::OpenDelim(token::Brace) = self.token.kind {
-                    self.parse_block_expr(
-                        None, self.token.span, BlockCheckMode::Default, ThinVec::new()
-                    )?
-                } else if self.token.is_ident() {
-                    // FIXME(const_generics): to distinguish between idents for types and consts,
-                    // we should introduce a GenericArg::Ident in the AST and distinguish when
-                    // lowering to the HIR. For now, idents for const args are not permitted.
-                    if self.token.is_bool_lit() {
-                        self.parse_literal_maybe_minus()?
-                    } else {
-                        return Err(
-                            self.fatal("identifiers may currently not be used for const generics")
-                        );
-                    }
-                } else {
-                    self.parse_literal_maybe_minus()?
-                };
-                let value = AnonConst {
-                    id: ast::DUMMY_NODE_ID,
-                    value: expr,
-                };
-                args.push(GenericArg::Const(value));
-                misplaced_assoc_ty_constraints.append(&mut assoc_ty_constraints);
-            } else if self.check_type() {
-                // Parse type argument.
-                args.push(GenericArg::Type(self.parse_ty()?));
-                misplaced_assoc_ty_constraints.append(&mut assoc_ty_constraints);
-            } else {
-                break
-            }
-
-            if !self.eat(&token::Comma) {
-                break
-            }
-        }
-
-        // FIXME: we would like to report this in ast_validation instead, but we currently do not
-        // preserve ordering of generic parameters with respect to associated type binding, so we
-        // lose that information after parsing.
-        if misplaced_assoc_ty_constraints.len() > 0 {
-            let mut err = self.struct_span_err(
-                args_lo.to(self.prev_span),
-                "associated type bindings must be declared after generic parameters",
-            );
-            for span in misplaced_assoc_ty_constraints {
-                err.span_label(
-                    span,
-                    "this associated type binding should be moved after the generic parameters",
-                );
-            }
-            err.emit();
-        }
-
-        Ok((args, constraints))
-    }
-}
diff --git a/src/libsyntax/parse/parser/stmt.rs b/src/libsyntax/parse/parser/stmt.rs
deleted file mode 100644
index 30e47b7a0b2..00000000000
--- a/src/libsyntax/parse/parser/stmt.rs
+++ /dev/null
@@ -1,480 +0,0 @@
-use super::{Parser, Restrictions, PrevTokenKind, SemiColonMode, BlockMode};
-use super::expr::LhsExpr;
-use super::path::PathStyle;
-use super::pat::GateOr;
-use super::diagnostics::Error;
-
-use crate::ptr::P;
-use crate::{maybe_whole, ThinVec};
-use crate::ast::{self, DUMMY_NODE_ID, Stmt, StmtKind, Local, Block, BlockCheckMode, Expr, ExprKind};
-use crate::ast::{Attribute, AttrStyle, VisibilityKind, MacStmtStyle, Mac, MacDelimiter};
-use crate::parse::DirectoryOwnership;
-use crate::util::classify;
-use crate::token;
-use crate::source_map::{respan, Span};
-use crate::symbol::{kw, sym};
-
-use std::mem;
-use errors::{PResult, Applicability};
-
-impl<'a> Parser<'a> {
-    /// Parses a statement. This stops just before trailing semicolons on everything but items.
-    /// e.g., a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed.
-    pub fn parse_stmt(&mut self) -> PResult<'a, Option<Stmt>> {
-        Ok(self.parse_stmt_(true))
-    }
-
-    fn parse_stmt_(&mut self, macro_legacy_warnings: bool) -> Option<Stmt> {
-        self.parse_stmt_without_recovery(macro_legacy_warnings).unwrap_or_else(|mut e| {
-            e.emit();
-            self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
-            None
-        })
-    }
-
-    fn parse_stmt_without_recovery(
-        &mut self,
-        macro_legacy_warnings: bool,
-    ) -> PResult<'a, Option<Stmt>> {
-        maybe_whole!(self, NtStmt, |x| Some(x));
-
-        let attrs = self.parse_outer_attributes()?;
-        let lo = self.token.span;
-
-        Ok(Some(if self.eat_keyword(kw::Let) {
-            Stmt {
-                id: DUMMY_NODE_ID,
-                kind: StmtKind::Local(self.parse_local(attrs.into())?),
-                span: lo.to(self.prev_span),
-            }
-        } else if let Some(macro_def) = self.eat_macro_def(
-            &attrs,
-            &respan(lo, VisibilityKind::Inherited),
-            lo,
-        )? {
-            Stmt {
-                id: DUMMY_NODE_ID,
-                kind: StmtKind::Item(macro_def),
-                span: lo.to(self.prev_span),
-            }
-        // Starts like a simple path, being careful to avoid contextual keywords
-        // such as a union items, item with `crate` visibility or auto trait items.
-        // Our goal here is to parse an arbitrary path `a::b::c` but not something that starts
-        // like a path (1 token), but it fact not a path.
-        // `union::b::c` - path, `union U { ... }` - not a path.
-        // `crate::b::c` - path, `crate struct S;` - not a path.
-        } else if self.token.is_path_start() &&
-                  !self.token.is_qpath_start() &&
-                  !self.is_union_item() &&
-                  !self.is_crate_vis() &&
-                  !self.is_auto_trait_item() &&
-                  !self.is_async_fn() {
-            let path = self.parse_path(PathStyle::Expr)?;
-
-            if !self.eat(&token::Not) {
-                let expr = if self.check(&token::OpenDelim(token::Brace)) {
-                    self.parse_struct_expr(lo, path, ThinVec::new())?
-                } else {
-                    let hi = self.prev_span;
-                    self.mk_expr(lo.to(hi), ExprKind::Path(None, path), ThinVec::new())
-                };
-
-                let expr = self.with_res(Restrictions::STMT_EXPR, |this| {
-                    let expr = this.parse_dot_or_call_expr_with(expr, lo, attrs.into())?;
-                    this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr))
-                })?;
-
-                return Ok(Some(Stmt {
-                    id: DUMMY_NODE_ID,
-                    kind: StmtKind::Expr(expr),
-                    span: lo.to(self.prev_span),
-                }));
-            }
-
-            let (delim, tts) = self.expect_delimited_token_tree()?;
-            let hi = self.prev_span;
-
-            let style = if delim == MacDelimiter::Brace {
-                MacStmtStyle::Braces
-            } else {
-                MacStmtStyle::NoBraces
-            };
-
-            let mac = Mac {
-                path,
-                tts,
-                delim,
-                span: lo.to(hi),
-                prior_type_ascription: self.last_type_ascription,
-            };
-            let kind = if delim == MacDelimiter::Brace ||
-                          self.token == token::Semi || self.token == token::Eof {
-                StmtKind::Mac(P((mac, style, attrs.into())))
-            }
-            // We used to incorrectly stop parsing macro-expanded statements here.
-            // If the next token will be an error anyway but could have parsed with the
-            // earlier behavior, stop parsing here and emit a warning to avoid breakage.
-            else if macro_legacy_warnings && self.token.can_begin_expr() &&
-                match self.token.kind {
-                    // These can continue an expression, so we can't stop parsing and warn.
-                    token::OpenDelim(token::Paren) | token::OpenDelim(token::Bracket) |
-                    token::BinOp(token::Minus) | token::BinOp(token::Star) |
-                    token::BinOp(token::And) | token::BinOp(token::Or) |
-                    token::AndAnd | token::OrOr |
-                    token::DotDot | token::DotDotDot | token::DotDotEq => false,
-                    _ => true,
-                }
-            {
-                self.warn_missing_semicolon();
-                StmtKind::Mac(P((mac, style, attrs.into())))
-            } else {
-                let e = self.mk_expr(mac.span, ExprKind::Mac(mac), ThinVec::new());
-                let e = self.maybe_recover_from_bad_qpath(e, true)?;
-                let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
-                let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
-                StmtKind::Expr(e)
-            };
-            Stmt {
-                id: DUMMY_NODE_ID,
-                span: lo.to(hi),
-                kind,
-            }
-        } else {
-            // FIXME: Bad copy of attrs
-            let old_directory_ownership =
-                mem::replace(&mut self.directory.ownership, DirectoryOwnership::UnownedViaBlock);
-            let item = self.parse_item_(attrs.clone(), false, true)?;
-            self.directory.ownership = old_directory_ownership;
-
-            match item {
-                Some(i) => Stmt {
-                    id: DUMMY_NODE_ID,
-                    span: lo.to(i.span),
-                    kind: StmtKind::Item(i),
-                },
-                None => {
-                    let unused_attrs = |attrs: &[Attribute], s: &mut Self| {
-                        if !attrs.is_empty() {
-                            if s.prev_token_kind == PrevTokenKind::DocComment {
-                                s.span_fatal_err(s.prev_span, Error::UselessDocComment).emit();
-                            } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) {
-                                s.span_err(
-                                    s.token.span, "expected statement after outer attribute"
-                                );
-                            }
-                        }
-                    };
-
-                    // Do not attempt to parse an expression if we're done here.
-                    if self.token == token::Semi {
-                        unused_attrs(&attrs, self);
-                        self.bump();
-                        let mut last_semi = lo;
-                        while self.token == token::Semi {
-                            last_semi = self.token.span;
-                            self.bump();
-                        }
-                        // We are encoding a string of semicolons as an
-                        // an empty tuple that spans the excess semicolons
-                        // to preserve this info until the lint stage
-                        return Ok(Some(Stmt {
-                            id: DUMMY_NODE_ID,
-                            span: lo.to(last_semi),
-                            kind: StmtKind::Semi(self.mk_expr(lo.to(last_semi),
-                                ExprKind::Tup(Vec::new()),
-                                ThinVec::new()
-                            )),
-                        }));
-                    }
-
-                    if self.token == token::CloseDelim(token::Brace) {
-                        unused_attrs(&attrs, self);
-                        return Ok(None);
-                    }
-
-                    // Remainder are line-expr stmts.
-                    let e = self.parse_expr_res(
-                        Restrictions::STMT_EXPR, Some(attrs.into()))?;
-                    Stmt {
-                        id: DUMMY_NODE_ID,
-                        span: lo.to(e.span),
-                        kind: StmtKind::Expr(e),
-                    }
-                }
-            }
-        }))
-    }
-
-    /// Parses a local variable declaration.
-    fn parse_local(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Local>> {
-        let lo = self.prev_span;
-        let pat = self.parse_top_pat(GateOr::Yes)?;
-
-        let (err, ty) = if self.eat(&token::Colon) {
-            // Save the state of the parser before parsing type normally, in case there is a `:`
-            // instead of an `=` typo.
-            let parser_snapshot_before_type = self.clone();
-            let colon_sp = self.prev_span;
-            match self.parse_ty() {
-                Ok(ty) => (None, Some(ty)),
-                Err(mut err) => {
-                    // Rewind to before attempting to parse the type and continue parsing.
-                    let parser_snapshot_after_type = self.clone();
-                    mem::replace(self, parser_snapshot_before_type);
-
-                    let snippet = self.span_to_snippet(pat.span).unwrap();
-                    err.span_label(pat.span, format!("while parsing the type for `{}`", snippet));
-                    (Some((parser_snapshot_after_type, colon_sp, err)), None)
-                }
-            }
-        } else {
-            (None, None)
-        };
-        let init = match (self.parse_initializer(err.is_some()), err) {
-            (Ok(init), None) => {  // init parsed, ty parsed
-                init
-            }
-            (Ok(init), Some((_, colon_sp, mut err))) => {  // init parsed, ty error
-                // Could parse the type as if it were the initializer, it is likely there was a
-                // typo in the code: `:` instead of `=`. Add suggestion and emit the error.
-                err.span_suggestion_short(
-                    colon_sp,
-                    "use `=` if you meant to assign",
-                    " =".to_string(),
-                    Applicability::MachineApplicable
-                );
-                err.emit();
-                // As this was parsed successfully, continue as if the code has been fixed for the
-                // rest of the file. It will still fail due to the emitted error, but we avoid
-                // extra noise.
-                init
-            }
-            (Err(mut init_err), Some((snapshot, _, ty_err))) => {  // init error, ty error
-                init_err.cancel();
-                // Couldn't parse the type nor the initializer, only raise the type error and
-                // return to the parser state before parsing the type as the initializer.
-                // let x: <parse_error>;
-                mem::replace(self, snapshot);
-                return Err(ty_err);
-            }
-            (Err(err), None) => {  // init error, ty parsed
-                // Couldn't parse the initializer and we're not attempting to recover a failed
-                // parse of the type, return the error.
-                return Err(err);
-            }
-        };
-        let hi = if self.token == token::Semi {
-            self.token.span
-        } else {
-            self.prev_span
-        };
-        Ok(P(ast::Local {
-            ty,
-            pat,
-            init,
-            id: DUMMY_NODE_ID,
-            span: lo.to(hi),
-            attrs,
-        }))
-    }
-
-    /// Parses the RHS of a local variable declaration (e.g., '= 14;').
-    fn parse_initializer(&mut self, skip_eq: bool) -> PResult<'a, Option<P<Expr>>> {
-        if self.eat(&token::Eq) {
-            Ok(Some(self.parse_expr()?))
-        } else if skip_eq {
-            Ok(Some(self.parse_expr()?))
-        } else {
-            Ok(None)
-        }
-    }
-
-    fn is_auto_trait_item(&self) -> bool {
-        // auto trait
-        (self.token.is_keyword(kw::Auto) &&
-            self.is_keyword_ahead(1, &[kw::Trait]))
-        || // unsafe auto trait
-        (self.token.is_keyword(kw::Unsafe) &&
-         self.is_keyword_ahead(1, &[kw::Auto]) &&
-         self.is_keyword_ahead(2, &[kw::Trait]))
-    }
-
-    /// Parses a block. No inner attributes are allowed.
-    pub fn parse_block(&mut self) -> PResult<'a, P<Block>> {
-        maybe_whole!(self, NtBlock, |x| x);
-
-        let lo = self.token.span;
-
-        if !self.eat(&token::OpenDelim(token::Brace)) {
-            let sp = self.token.span;
-            let tok = self.this_token_descr();
-            let mut e = self.span_fatal(sp, &format!("expected `{{`, found {}", tok));
-            let do_not_suggest_help =
-                self.token.is_keyword(kw::In) || self.token == token::Colon;
-
-            if self.token.is_ident_named(sym::and) {
-                e.span_suggestion_short(
-                    self.token.span,
-                    "use `&&` instead of `and` for the boolean operator",
-                    "&&".to_string(),
-                    Applicability::MaybeIncorrect,
-                );
-            }
-            if self.token.is_ident_named(sym::or) {
-                e.span_suggestion_short(
-                    self.token.span,
-                    "use `||` instead of `or` for the boolean operator",
-                    "||".to_string(),
-                    Applicability::MaybeIncorrect,
-                );
-            }
-
-            // Check to see if the user has written something like
-            //
-            //    if (cond)
-            //      bar;
-            //
-            // which is valid in other languages, but not Rust.
-            match self.parse_stmt_without_recovery(false) {
-                Ok(Some(stmt)) => {
-                    if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace))
-                        || do_not_suggest_help {
-                        // If the next token is an open brace (e.g., `if a b {`), the place-
-                        // inside-a-block suggestion would be more likely wrong than right.
-                        e.span_label(sp, "expected `{`");
-                        return Err(e);
-                    }
-                    let mut stmt_span = stmt.span;
-                    // Expand the span to include the semicolon, if it exists.
-                    if self.eat(&token::Semi) {
-                        stmt_span = stmt_span.with_hi(self.prev_span.hi());
-                    }
-                    if let Ok(snippet) = self.span_to_snippet(stmt_span) {
-                        e.span_suggestion(
-                            stmt_span,
-                            "try placing this code inside a block",
-                            format!("{{ {} }}", snippet),
-                            // Speculative; has been misleading in the past (#46836).
-                            Applicability::MaybeIncorrect,
-                        );
-                    }
-                }
-                Err(mut e) => {
-                    self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
-                    e.cancel();
-                }
-                _ => ()
-            }
-            e.span_label(sp, "expected `{`");
-            return Err(e);
-        }
-
-        self.parse_block_tail(lo, BlockCheckMode::Default)
-    }
-
-    /// Parses a block. Inner attributes are allowed.
-    pub(super) fn parse_inner_attrs_and_block(
-        &mut self
-    ) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
-        maybe_whole!(self, NtBlock, |x| (Vec::new(), x));
-
-        let lo = self.token.span;
-        self.expect(&token::OpenDelim(token::Brace))?;
-        Ok((self.parse_inner_attributes()?,
-            self.parse_block_tail(lo, BlockCheckMode::Default)?))
-    }
-
-    /// Parses the rest of a block expression or function body.
-    /// Precondition: already parsed the '{'.
-    pub(super) fn parse_block_tail(
-        &mut self,
-        lo: Span,
-        s: BlockCheckMode
-    ) -> PResult<'a, P<Block>> {
-        let mut stmts = vec![];
-        while !self.eat(&token::CloseDelim(token::Brace)) {
-            if self.token == token::Eof {
-                break;
-            }
-            let stmt = match self.parse_full_stmt(false) {
-                Err(mut err) => {
-                    self.maybe_annotate_with_ascription(&mut err, false);
-                    err.emit();
-                    self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore);
-                    Some(Stmt {
-                        id: DUMMY_NODE_ID,
-                        kind: StmtKind::Expr(self.mk_expr_err(self.token.span)),
-                        span: self.token.span,
-                    })
-                }
-                Ok(stmt) => stmt,
-            };
-            if let Some(stmt) = stmt {
-                stmts.push(stmt);
-            } else {
-                // Found only `;` or `}`.
-                continue;
-            };
-        }
-        Ok(P(ast::Block {
-            stmts,
-            id: DUMMY_NODE_ID,
-            rules: s,
-            span: lo.to(self.prev_span),
-        }))
-    }
-
-    /// Parses a statement, including the trailing semicolon.
-    pub fn parse_full_stmt(&mut self, macro_legacy_warnings: bool) -> PResult<'a, Option<Stmt>> {
-        // Skip looking for a trailing semicolon when we have an interpolated statement.
-        maybe_whole!(self, NtStmt, |x| Some(x));
-
-        let mut stmt = match self.parse_stmt_without_recovery(macro_legacy_warnings)? {
-            Some(stmt) => stmt,
-            None => return Ok(None),
-        };
-
-        let mut eat_semi = true;
-        match stmt.kind {
-            StmtKind::Expr(ref expr) if self.token != token::Eof => {
-                // expression without semicolon
-                if classify::expr_requires_semi_to_be_stmt(expr) {
-                    // Just check for errors and recover; do not eat semicolon yet.
-                    if let Err(mut e) =
-                        self.expect_one_of(&[], &[token::Semi, token::CloseDelim(token::Brace)])
-                    {
-                        e.emit();
-                        self.recover_stmt();
-                        // Don't complain about type errors in body tail after parse error (#57383).
-                        let sp = expr.span.to(self.prev_span);
-                        stmt.kind = StmtKind::Expr(self.mk_expr_err(sp));
-                    }
-                }
-            }
-            StmtKind::Local(..) => {
-                // We used to incorrectly allow a macro-expanded let statement to lack a semicolon.
-                if macro_legacy_warnings && self.token != token::Semi {
-                    self.warn_missing_semicolon();
-                } else {
-                    self.expect_semi()?;
-                    eat_semi = false;
-                }
-            }
-            _ => {}
-        }
-
-        if eat_semi && self.eat(&token::Semi) {
-            stmt = stmt.add_trailing_semicolon();
-        }
-        stmt.span = stmt.span.to(self.prev_span);
-        Ok(Some(stmt))
-    }
-
-    fn warn_missing_semicolon(&self) {
-        self.diagnostic().struct_span_warn(self.token.span, {
-            &format!("expected `;`, found {}", self.this_token_descr())
-        }).note({
-            "this was erroneously allowed and will become a hard error in a future release"
-        }).emit();
-    }
-}
diff --git a/src/libsyntax/parse/parser/ty.rs b/src/libsyntax/parse/parser/ty.rs
deleted file mode 100644
index a891634e611..00000000000
--- a/src/libsyntax/parse/parser/ty.rs
+++ /dev/null
@@ -1,458 +0,0 @@
-use super::{Parser, PathStyle, PrevTokenKind, TokenType};
-use super::item::ParamCfg;
-
-use crate::{maybe_whole, maybe_recover_from_interpolated_ty_qpath};
-use crate::ptr::P;
-use crate::ast::{self, Ty, TyKind, MutTy, BareFnTy, FunctionRetTy, GenericParam, Lifetime, Ident};
-use crate::ast::{TraitBoundModifier, TraitObjectSyntax, GenericBound, GenericBounds, PolyTraitRef};
-use crate::ast::{Mutability, AnonConst, Mac};
-use crate::token::{self, Token};
-use crate::source_map::Span;
-use crate::symbol::{kw};
-
-use errors::{PResult, Applicability, pluralize};
-
-/// Returns `true` if `IDENT t` can start a type -- `IDENT::a::b`, `IDENT<u8, u8>`,
-/// `IDENT<<u8 as Trait>::AssocTy>`.
-///
-/// Types can also be of the form `IDENT(u8, u8) -> u8`, however this assumes
-/// that `IDENT` is not the ident of a fn trait.
-fn can_continue_type_after_non_fn_ident(t: &Token) -> bool {
-    t == &token::ModSep || t == &token::Lt ||
-    t == &token::BinOp(token::Shl)
-}
-
-impl<'a> Parser<'a> {
-    /// Parses a type.
-    pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> {
-        self.parse_ty_common(true, true, false)
-    }
-
-    /// Parses a type in restricted contexts where `+` is not permitted.
-    ///
-    /// Example 1: `&'a TYPE`
-    ///     `+` is prohibited to maintain operator priority (P(+) < P(&)).
-    /// Example 2: `value1 as TYPE + value2`
-    ///     `+` is prohibited to avoid interactions with expression grammar.
-    pub(super) fn parse_ty_no_plus(&mut self) -> PResult<'a, P<Ty>> {
-        self.parse_ty_common(false, true, false)
-    }
-
-    /// Parses an optional return type `[ -> TY ]` in a function declaration.
-    pub(super) fn parse_ret_ty(&mut self, allow_plus: bool) -> PResult<'a, FunctionRetTy> {
-        if self.eat(&token::RArrow) {
-            Ok(FunctionRetTy::Ty(self.parse_ty_common(allow_plus, true, false)?))
-        } else {
-            Ok(FunctionRetTy::Default(self.token.span.shrink_to_lo()))
-        }
-    }
-
-    pub(super) fn parse_ty_common(&mut self, allow_plus: bool, allow_qpath_recovery: bool,
-                       allow_c_variadic: bool) -> PResult<'a, P<Ty>> {
-        maybe_recover_from_interpolated_ty_qpath!(self, allow_qpath_recovery);
-        maybe_whole!(self, NtTy, |x| x);
-
-        let lo = self.token.span;
-        let mut impl_dyn_multi = false;
-        let kind = if self.eat(&token::OpenDelim(token::Paren)) {
-            // `(TYPE)` is a parenthesized type.
-            // `(TYPE,)` is a tuple with a single field of type TYPE.
-            let mut ts = vec![];
-            let mut last_comma = false;
-            while self.token != token::CloseDelim(token::Paren) {
-                ts.push(self.parse_ty()?);
-                if self.eat(&token::Comma) {
-                    last_comma = true;
-                } else {
-                    last_comma = false;
-                    break;
-                }
-            }
-            let trailing_plus = self.prev_token_kind == PrevTokenKind::Plus;
-            self.expect(&token::CloseDelim(token::Paren))?;
-
-            if ts.len() == 1 && !last_comma {
-                let ty = ts.into_iter().nth(0).unwrap().into_inner();
-                let maybe_bounds = allow_plus && self.token.is_like_plus();
-                match ty.kind {
-                    // `(TY_BOUND_NOPAREN) + BOUND + ...`.
-                    TyKind::Path(None, ref path) if maybe_bounds => {
-                        self.parse_remaining_bounds(Vec::new(), path.clone(), lo, true)?
-                    }
-                    TyKind::TraitObject(ref bounds, TraitObjectSyntax::None)
-                            if maybe_bounds && bounds.len() == 1 && !trailing_plus => {
-                        let path = match bounds[0] {
-                            GenericBound::Trait(ref pt, ..) => pt.trait_ref.path.clone(),
-                            GenericBound::Outlives(..) => self.bug("unexpected lifetime bound"),
-                        };
-                        self.parse_remaining_bounds(Vec::new(), path, lo, true)?
-                    }
-                    // `(TYPE)`
-                    _ => TyKind::Paren(P(ty))
-                }
-            } else {
-                TyKind::Tup(ts)
-            }
-        } else if self.eat(&token::Not) {
-            // Never type `!`
-            TyKind::Never
-        } else if self.eat(&token::BinOp(token::Star)) {
-            // Raw pointer
-            TyKind::Ptr(self.parse_ptr()?)
-        } else if self.eat(&token::OpenDelim(token::Bracket)) {
-            // Array or slice
-            let t = self.parse_ty()?;
-            // Parse optional `; EXPR` in `[TYPE; EXPR]`
-            let t = match self.maybe_parse_fixed_length_of_vec()? {
-                None => TyKind::Slice(t),
-                Some(length) => TyKind::Array(t, AnonConst {
-                    id: ast::DUMMY_NODE_ID,
-                    value: length,
-                }),
-            };
-            self.expect(&token::CloseDelim(token::Bracket))?;
-            t
-        } else if self.check(&token::BinOp(token::And)) || self.check(&token::AndAnd) {
-            // Reference
-            self.expect_and()?;
-            self.parse_borrowed_pointee()?
-        } else if self.eat_keyword_noexpect(kw::Typeof) {
-            // `typeof(EXPR)`
-            // In order to not be ambiguous, the type must be surrounded by parens.
-            self.expect(&token::OpenDelim(token::Paren))?;
-            let e = AnonConst {
-                id: ast::DUMMY_NODE_ID,
-                value: self.parse_expr()?,
-            };
-            self.expect(&token::CloseDelim(token::Paren))?;
-            TyKind::Typeof(e)
-        } else if self.eat_keyword(kw::Underscore) {
-            // A type to be inferred `_`
-            TyKind::Infer
-        } else if self.token_is_bare_fn_keyword() {
-            // Function pointer type
-            self.parse_ty_bare_fn(Vec::new())?
-        } else if self.check_keyword(kw::For) {
-            // Function pointer type or bound list (trait object type) starting with a poly-trait.
-            //   `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
-            //   `for<'lt> Trait1<'lt> + Trait2 + 'a`
-            let lo = self.token.span;
-            let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
-            if self.token_is_bare_fn_keyword() {
-                self.parse_ty_bare_fn(lifetime_defs)?
-            } else {
-                let path = self.parse_path(PathStyle::Type)?;
-                let parse_plus = allow_plus && self.check_plus();
-                self.parse_remaining_bounds(lifetime_defs, path, lo, parse_plus)?
-            }
-        } else if self.eat_keyword(kw::Impl) {
-            // Always parse bounds greedily for better error recovery.
-            let bounds = self.parse_generic_bounds(None)?;
-            impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
-            TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds)
-        } else if self.check_keyword(kw::Dyn) &&
-                  (self.token.span.rust_2018() ||
-                   self.look_ahead(1, |t| t.can_begin_bound() &&
-                                          !can_continue_type_after_non_fn_ident(t))) {
-            self.bump(); // `dyn`
-            // Always parse bounds greedily for better error recovery.
-            let bounds = self.parse_generic_bounds(None)?;
-            impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus;
-            TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn)
-        } else if self.check(&token::Question) ||
-                  self.check_lifetime() && self.look_ahead(1, |t| t.is_like_plus()) {
-            // Bound list (trait object type)
-            TyKind::TraitObject(self.parse_generic_bounds_common(allow_plus, None)?,
-                                TraitObjectSyntax::None)
-        } else if self.eat_lt() {
-            // Qualified path
-            let (qself, path) = self.parse_qpath(PathStyle::Type)?;
-            TyKind::Path(Some(qself), path)
-        } else if self.token.is_path_start() {
-            // Simple path
-            let path = self.parse_path(PathStyle::Type)?;
-            if self.eat(&token::Not) {
-                // Macro invocation in type position
-                let (delim, tts) = self.expect_delimited_token_tree()?;
-                let mac = Mac {
-                    path,
-                    tts,
-                    delim,
-                    span: lo.to(self.prev_span),
-                    prior_type_ascription: self.last_type_ascription,
-                };
-                TyKind::Mac(mac)
-            } else {
-                // Just a type path or bound list (trait object type) starting with a trait.
-                //   `Type`
-                //   `Trait1 + Trait2 + 'a`
-                if allow_plus && self.check_plus() {
-                    self.parse_remaining_bounds(Vec::new(), path, lo, true)?
-                } else {
-                    TyKind::Path(None, path)
-                }
-            }
-        } else if self.check(&token::DotDotDot) {
-            if allow_c_variadic {
-                self.eat(&token::DotDotDot);
-                TyKind::CVarArgs
-            } else {
-                return Err(struct_span_fatal!(
-                    self.sess.span_diagnostic,
-                    self.token.span,
-                    E0743,
-                    "only foreign functions are allowed to be C-variadic",
-                ));
-            }
-        } else {
-            let msg = format!("expected type, found {}", self.this_token_descr());
-            let mut err = self.fatal(&msg);
-            err.span_label(self.token.span, "expected type");
-            self.maybe_annotate_with_ascription(&mut err, true);
-            return Err(err);
-        };
-
-        let span = lo.to(self.prev_span);
-        let ty = self.mk_ty(span, kind);
-
-        // Try to recover from use of `+` with incorrect priority.
-        self.maybe_report_ambiguous_plus(allow_plus, impl_dyn_multi, &ty);
-        self.maybe_recover_from_bad_type_plus(allow_plus, &ty)?;
-        self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery)
-    }
-
-    fn parse_remaining_bounds(&mut self, generic_params: Vec<GenericParam>, path: ast::Path,
-                              lo: Span, parse_plus: bool) -> PResult<'a, TyKind> {
-        let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_span));
-        let mut bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifier::None)];
-        if parse_plus {
-            self.eat_plus(); // `+`, or `+=` gets split and `+` is discarded
-            bounds.append(&mut self.parse_generic_bounds(Some(self.prev_span))?);
-        }
-        Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None))
-    }
-
-    fn parse_ptr(&mut self) -> PResult<'a, MutTy> {
-        let mutbl = self.parse_const_or_mut().unwrap_or_else(|| {
-            let span = self.prev_span;
-            let msg = "expected mut or const in raw pointer type";
-            self.struct_span_err(span, msg)
-                .span_label(span, msg)
-                .help("use `*mut T` or `*const T` as appropriate")
-                .emit();
-            Mutability::Immutable
-        });
-        let t = self.parse_ty_no_plus()?;
-        Ok(MutTy { ty: t, mutbl })
-    }
-
-    fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<'a, Option<P<ast::Expr>>> {
-        if self.eat(&token::Semi) {
-            Ok(Some(self.parse_expr()?))
-        } else {
-            Ok(None)
-        }
-    }
-
-    fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> {
-        let opt_lifetime = if self.check_lifetime() { Some(self.expect_lifetime()) } else { None };
-        let mutbl = self.parse_mutability();
-        let ty = self.parse_ty_no_plus()?;
-        return Ok(TyKind::Rptr(opt_lifetime, MutTy { ty, mutbl }));
-    }
-
-    /// Is the current token one of the keywords that signals a bare function type?
-    fn token_is_bare_fn_keyword(&mut self) -> bool {
-        self.check_keyword(kw::Fn) ||
-            self.check_keyword(kw::Unsafe) ||
-            self.check_keyword(kw::Extern)
-    }
-
-    /// Parses a `TyKind::BareFn` type.
-    fn parse_ty_bare_fn(&mut self, generic_params: Vec<GenericParam>) -> PResult<'a, TyKind> {
-        /*
-
-        [unsafe] [extern "ABI"] fn (S) -> T
-         ^~~~^           ^~~~^     ^~^    ^
-           |               |        |     |
-           |               |        |   Return type
-           |               |      Argument types
-           |               |
-           |              ABI
-        Function Style
-        */
-
-        let unsafety = self.parse_unsafety();
-        let abi = self.parse_extern_abi()?;
-        self.expect_keyword(kw::Fn)?;
-        let cfg = ParamCfg {
-            is_self_allowed: false,
-            allow_c_variadic: true,
-            is_name_required: |_| false,
-        };
-        let decl = self.parse_fn_decl(cfg, false)?;
-        Ok(TyKind::BareFn(P(BareFnTy {
-            abi,
-            unsafety,
-            generic_params,
-            decl,
-        })))
-    }
-
-    pub(super) fn parse_generic_bounds(&mut self,
-                                  colon_span: Option<Span>) -> PResult<'a, GenericBounds> {
-        self.parse_generic_bounds_common(true, colon_span)
-    }
-
-    /// Parses bounds of a type parameter `BOUND + BOUND + ...`, possibly with trailing `+`.
-    ///
-    /// ```
-    /// BOUND = TY_BOUND | LT_BOUND
-    /// LT_BOUND = LIFETIME (e.g., `'a`)
-    /// TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
-    /// TY_BOUND_NOPAREN = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g., `?for<'a: 'b> m::Trait<'a>`)
-    /// ```
-    fn parse_generic_bounds_common(&mut self,
-                                   allow_plus: bool,
-                                   colon_span: Option<Span>) -> PResult<'a, GenericBounds> {
-        let mut bounds = Vec::new();
-        let mut negative_bounds = Vec::new();
-        let mut last_plus_span = None;
-        let mut was_negative = false;
-        loop {
-            // This needs to be synchronized with `TokenKind::can_begin_bound`.
-            let is_bound_start = self.check_path() || self.check_lifetime() ||
-                                 self.check(&token::Not) || // used for error reporting only
-                                 self.check(&token::Question) ||
-                                 self.check_keyword(kw::For) ||
-                                 self.check(&token::OpenDelim(token::Paren));
-            if is_bound_start {
-                let lo = self.token.span;
-                let has_parens = self.eat(&token::OpenDelim(token::Paren));
-                let inner_lo = self.token.span;
-                let is_negative = self.eat(&token::Not);
-                let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
-                if self.token.is_lifetime() {
-                    if let Some(question_span) = question {
-                        self.span_err(question_span,
-                                      "`?` may only modify trait bounds, not lifetime bounds");
-                    }
-                    bounds.push(GenericBound::Outlives(self.expect_lifetime()));
-                    if has_parens {
-                        let inner_span = inner_lo.to(self.prev_span);
-                        self.expect(&token::CloseDelim(token::Paren))?;
-                        let mut err = self.struct_span_err(
-                            lo.to(self.prev_span),
-                            "parenthesized lifetime bounds are not supported"
-                        );
-                        if let Ok(snippet) = self.span_to_snippet(inner_span) {
-                            err.span_suggestion_short(
-                                lo.to(self.prev_span),
-                                "remove the parentheses",
-                                snippet.to_owned(),
-                                Applicability::MachineApplicable
-                            );
-                        }
-                        err.emit();
-                    }
-                } else {
-                    let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
-                    let path = self.parse_path(PathStyle::Type)?;
-                    if has_parens {
-                        self.expect(&token::CloseDelim(token::Paren))?;
-                    }
-                    let poly_span = lo.to(self.prev_span);
-                    if is_negative {
-                        was_negative = true;
-                        if let Some(sp) = last_plus_span.or(colon_span) {
-                            negative_bounds.push(sp.to(poly_span));
-                        }
-                    } else {
-                        let poly_trait = PolyTraitRef::new(lifetime_defs, path, poly_span);
-                        let modifier = if question.is_some() {
-                            TraitBoundModifier::Maybe
-                        } else {
-                            TraitBoundModifier::None
-                        };
-                        bounds.push(GenericBound::Trait(poly_trait, modifier));
-                    }
-                }
-            } else {
-                break
-            }
-
-            if !allow_plus || !self.eat_plus() {
-                break
-            } else {
-                last_plus_span = Some(self.prev_span);
-            }
-        }
-
-        if !negative_bounds.is_empty() || was_negative {
-            let negative_bounds_len = negative_bounds.len();
-            let last_span = negative_bounds.last().map(|sp| *sp);
-            let mut err = self.struct_span_err(
-                negative_bounds,
-                "negative trait bounds are not supported",
-            );
-            if let Some(sp) = last_span {
-                err.span_label(sp, "negative trait bounds are not supported");
-            }
-            if let Some(bound_list) = colon_span {
-                let bound_list = bound_list.to(self.prev_span);
-                let mut new_bound_list = String::new();
-                if !bounds.is_empty() {
-                    let mut snippets = bounds.iter().map(|bound| bound.span())
-                        .map(|span| self.span_to_snippet(span));
-                    while let Some(Ok(snippet)) = snippets.next() {
-                        new_bound_list.push_str(" + ");
-                        new_bound_list.push_str(&snippet);
-                    }
-                    new_bound_list = new_bound_list.replacen(" +", ":", 1);
-                }
-                err.span_suggestion_hidden(
-                    bound_list,
-                    &format!("remove the trait bound{}", pluralize!(negative_bounds_len)),
-                    new_bound_list,
-                    Applicability::MachineApplicable,
-                );
-            }
-            err.emit();
-        }
-
-        return Ok(bounds);
-    }
-
-    pub(super) fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> {
-        if self.eat_keyword(kw::For) {
-            self.expect_lt()?;
-            let params = self.parse_generic_params()?;
-            self.expect_gt()?;
-            // We rely on AST validation to rule out invalid cases: There must not be type
-            // parameters, and the lifetime parameters must not have bounds.
-            Ok(params)
-        } else {
-            Ok(Vec::new())
-        }
-    }
-
-    pub fn check_lifetime(&mut self) -> bool {
-        self.expected_tokens.push(TokenType::Lifetime);
-        self.token.is_lifetime()
-    }
-
-    /// Parses a single lifetime `'a` or panics.
-    pub fn expect_lifetime(&mut self) -> Lifetime {
-        if let Some(ident) = self.token.lifetime() {
-            let span = self.token.span;
-            self.bump();
-            Lifetime { ident: Ident::new(ident.name, span), id: ast::DUMMY_NODE_ID }
-        } else {
-            self.span_bug(self.token.span, "not a lifetime")
-        }
-    }
-
-    pub(super) fn mk_ty(&self, span: Span, kind: TyKind) -> P<Ty> {
-        P(Ty { kind, span, id: ast::DUMMY_NODE_ID })
-    }
-}
diff --git a/src/libsyntax/parse/validate_attr.rs b/src/libsyntax/parse/validate_attr.rs
deleted file mode 100644
index 6cc8a1ec33e..00000000000
--- a/src/libsyntax/parse/validate_attr.rs
+++ /dev/null
@@ -1,112 +0,0 @@
-//! Meta-syntax validation logic of attributes for post-expansion.
-
-use crate::ast::{self, Attribute, AttrKind, Ident, MetaItem};
-use crate::attr::{AttributeTemplate, mk_name_value_item_str};
-use crate::sess::ParseSess;
-use crate::feature_gate::BUILTIN_ATTRIBUTE_MAP;
-use crate::early_buffered_lints::BufferedEarlyLintId;
-use crate::token;
-use crate::tokenstream::TokenTree;
-
-use errors::{PResult, Applicability};
-use syntax_pos::{Symbol, sym};
-
-pub fn check_meta(sess: &ParseSess, attr: &Attribute) {
-    let attr_info =
-        attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name)).map(|a| **a);
-
-    // Check input tokens for built-in and key-value attributes.
-    match attr_info {
-        // `rustc_dummy` doesn't have any restrictions specific to built-in attributes.
-        Some((name, _, template, _)) if name != sym::rustc_dummy =>
-            check_builtin_attribute(sess, attr, name, template),
-        _ => if let Some(TokenTree::Token(token)) = attr.get_normal_item().tokens.trees().next() {
-            if token == token::Eq {
-                // All key-value attributes are restricted to meta-item syntax.
-                parse_meta(sess, attr).map_err(|mut err| err.emit()).ok();
-            }
-        }
-    }
-}
-
-pub fn parse_meta<'a>(sess: &'a ParseSess, attr: &Attribute) -> PResult<'a, MetaItem> {
-    Ok(match attr.kind {
-        AttrKind::Normal(ref item) => MetaItem {
-            path: item.path.clone(),
-            kind: super::parse_in_attr(sess, attr, |p| p.parse_meta_item_kind())?,
-            span: attr.span,
-        },
-        AttrKind::DocComment(comment) => {
-            mk_name_value_item_str(Ident::new(sym::doc, attr.span), comment, attr.span)
-        }
-    })
-}
-
-pub fn check_builtin_attribute(
-    sess: &ParseSess,
-    attr: &Attribute,
-    name: Symbol,
-    template: AttributeTemplate,
-) {
-    // Some special attributes like `cfg` must be checked
-    // before the generic check, so we skip them here.
-    let should_skip = |name| name == sym::cfg;
-    // Some of previously accepted forms were used in practice,
-    // report them as warnings for now.
-    let should_warn = |name| name == sym::doc || name == sym::ignore ||
-                             name == sym::inline || name == sym::link ||
-                             name == sym::test || name == sym::bench;
-
-    match parse_meta(sess, attr) {
-        Ok(meta) => if !should_skip(name) && !template.compatible(&meta.kind) {
-            let error_msg = format!("malformed `{}` attribute input", name);
-            let mut msg = "attribute must be of the form ".to_owned();
-            let mut suggestions = vec![];
-            let mut first = true;
-            if template.word {
-                first = false;
-                let code = format!("#[{}]", name);
-                msg.push_str(&format!("`{}`", &code));
-                suggestions.push(code);
-            }
-            if let Some(descr) = template.list {
-                if !first {
-                    msg.push_str(" or ");
-                }
-                first = false;
-                let code = format!("#[{}({})]", name, descr);
-                msg.push_str(&format!("`{}`", &code));
-                suggestions.push(code);
-            }
-            if let Some(descr) = template.name_value_str {
-                if !first {
-                    msg.push_str(" or ");
-                }
-                let code = format!("#[{} = \"{}\"]", name, descr);
-                msg.push_str(&format!("`{}`", &code));
-                suggestions.push(code);
-            }
-            if should_warn(name) {
-                sess.buffer_lint(
-                    BufferedEarlyLintId::IllFormedAttributeInput,
-                    meta.span,
-                    ast::CRATE_NODE_ID,
-                    &msg,
-                );
-            } else {
-                sess.span_diagnostic.struct_span_err(meta.span, &error_msg)
-                    .span_suggestions(
-                        meta.span,
-                        if suggestions.len() == 1 {
-                            "must be of the form"
-                        } else {
-                            "the following are the possible correct uses"
-                        },
-                        suggestions.into_iter(),
-                        Applicability::HasPlaceholders,
-                    ).emit();
-            }
-        }
-        Err(mut err) => err.emit(),
-    }
-}
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 04f096200b8..f154b7bde98 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -321,7 +321,7 @@ fn token_to_string_ext(token: &Token, convert_dollar_crate: bool) -> String {
     token_kind_to_string_ext(&token.kind, convert_dollar_crate)
 }
 
-crate fn nonterminal_to_string(nt: &Nonterminal) -> String {
+pub fn nonterminal_to_string(nt: &Nonterminal) -> String {
     match *nt {
         token::NtExpr(ref e)        => expr_to_string(e),
         token::NtMeta(ref e)        => attr_item_to_string(e),
@@ -958,7 +958,7 @@ impl<'a> State<'a> {
         }
     }
 
-    crate fn print_opt_lifetime(&mut self, lifetime: &Option<ast::Lifetime>) {
+    pub fn print_opt_lifetime(&mut self, lifetime: &Option<ast::Lifetime>) {
         if let Some(lt) = *lifetime {
             self.print_lifetime(lt);
             self.nbsp();
@@ -973,7 +973,7 @@ impl<'a> State<'a> {
         }
     }
 
-    crate fn print_type(&mut self, ty: &ast::Ty) {
+    pub fn print_type(&mut self, ty: &ast::Ty) {
         self.maybe_print_comment(ty.span.lo());
         self.ibox(0);
         match ty.kind {
@@ -1998,7 +1998,7 @@ impl<'a> State<'a> {
         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
     }
 
-    crate fn print_expr(&mut self, expr: &ast::Expr) {
+    pub fn print_expr(&mut self, expr: &ast::Expr) {
         self.print_expr_outer_attr_style(expr, true)
     }
 
@@ -2335,7 +2335,7 @@ impl<'a> State<'a> {
         }
     }
 
-    crate fn print_usize(&mut self, i: usize) {
+    pub fn print_usize(&mut self, i: usize) {
         self.s.word(i.to_string())
     }
 
@@ -2604,7 +2604,7 @@ impl<'a> State<'a> {
         }
     }
 
-    crate fn print_type_bounds(&mut self, prefix: &'static str, bounds: &[ast::GenericBound]) {
+    pub fn print_type_bounds(&mut self, prefix: &'static str, bounds: &[ast::GenericBound]) {
         if !bounds.is_empty() {
             self.s.word(prefix);
             let mut first = true;
@@ -2763,7 +2763,7 @@ impl<'a> State<'a> {
         }
     }
 
-    crate fn print_mutability(&mut self, mutbl: ast::Mutability) {
+    pub fn print_mutability(&mut self, mutbl: ast::Mutability) {
         match mutbl {
             ast::Mutability::Mutable => self.word_nbsp("mut"),
             ast::Mutability::Immutable => {},
diff --git a/src/libsyntax/sess.rs b/src/libsyntax/sess.rs
index 5e96b27c970..953f0d1d190 100644
--- a/src/libsyntax/sess.rs
+++ b/src/libsyntax/sess.rs
@@ -71,14 +71,14 @@ impl GatedSpans {
 /// Info about a parsing session.
 pub struct ParseSess {
     pub span_diagnostic: Handler,
-    crate unstable_features: UnstableFeatures,
+    pub unstable_features: UnstableFeatures,
     pub config: CrateConfig,
     pub edition: Edition,
     pub missing_fragment_specifiers: Lock<FxHashSet<Span>>,
     /// Places where raw identifiers were used. This is used for feature-gating raw identifiers.
     pub raw_identifier_spans: Lock<Vec<Span>>,
     /// Used to determine and report recursive module inclusions.
-    pub(super) included_mod_stack: Lock<Vec<PathBuf>>,
+    pub included_mod_stack: Lock<Vec<PathBuf>>,
     source_map: Lrc<SourceMap>,
     pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
     /// Contains the spans of block expressions that could have been incomplete based on the
diff --git a/src/libsyntax/token.rs b/src/libsyntax/token.rs
index 6f3da344ccf..c70e3442703 100644
--- a/src/libsyntax/token.rs
+++ b/src/libsyntax/token.rs
@@ -107,14 +107,14 @@ impl fmt::Display for Lit {
 
 impl LitKind {
     /// An English article for the literal token kind.
-    crate fn article(self) -> &'static str {
+    pub fn article(self) -> &'static str {
         match self {
             Integer | Err => "an",
             _ => "a",
         }
     }
 
-    crate fn descr(self) -> &'static str {
+    pub fn descr(self) -> &'static str {
         match self {
             Bool => panic!("literal token contains `Lit::Bool`"),
             Byte => "byte",
@@ -141,12 +141,12 @@ impl Lit {
     }
 }
 
-pub(crate) fn ident_can_begin_expr(name: ast::Name, span: Span, is_raw: bool) -> bool {
+pub fn ident_can_begin_expr(name: ast::Name, span: Span, is_raw: bool) -> bool {
     let ident_token = Token::new(Ident(name, is_raw), span);
     token_can_begin_expr(&ident_token)
 }
 
-pub(crate) fn token_can_begin_expr(ident_token: &Token) -> bool {
+pub fn token_can_begin_expr(ident_token: &Token) -> bool {
     !ident_token.is_reserved_ident() ||
     ident_token.is_path_segment_keyword() ||
     match ident_token.kind {
@@ -276,7 +276,7 @@ impl TokenKind {
 
     /// Returns tokens that are likely to be typed accidentally instead of the current token.
     /// Enables better error recovery when the wrong token is found.
-    crate fn similar_tokens(&self) -> Option<Vec<TokenKind>> {
+    pub fn similar_tokens(&self) -> Option<Vec<TokenKind>> {
         match *self {
             Comma => Some(vec![Dot, Lt, Semi]),
             Semi => Some(vec![Colon, Comma]),
@@ -291,7 +291,7 @@ impl Token {
     }
 
     /// Some token that will be thrown away later.
-    crate fn dummy() -> Self {
+    pub fn dummy() -> Self {
         Token::new(TokenKind::Whitespace, DUMMY_SP)
     }
 
@@ -305,7 +305,7 @@ impl Token {
         mem::replace(self, Token::dummy())
     }
 
-    crate fn is_op(&self) -> bool {
+    pub fn is_op(&self) -> bool {
         match self.kind {
             OpenDelim(..) | CloseDelim(..) | Literal(..) | DocComment(..) |
             Ident(..) | Lifetime(..) | Interpolated(..) |
@@ -314,7 +314,7 @@ impl Token {
         }
     }
 
-    crate fn is_like_plus(&self) -> bool {
+    pub fn is_like_plus(&self) -> bool {
         match self.kind {
             BinOp(Plus) | BinOpEq(Plus) => true,
             _ => false,
@@ -377,7 +377,7 @@ impl Token {
     }
 
     /// Returns `true` if the token can appear at the start of a const param.
-    crate fn can_begin_const_arg(&self) -> bool {
+    pub fn can_begin_const_arg(&self) -> bool {
         match self.kind {
             OpenDelim(Brace) => true,
             Interpolated(ref nt) => match **nt {
@@ -389,7 +389,7 @@ impl Token {
     }
 
     /// Returns `true` if the token can appear at the start of a generic bound.
-    crate fn can_begin_bound(&self) -> bool {
+    pub fn can_begin_bound(&self) -> bool {
         self.is_path_start() || self.is_lifetime() || self.is_keyword(kw::For) ||
         self == &Question || self == &OpenDelim(Paren)
     }
@@ -446,13 +446,13 @@ impl Token {
     }
 
     /// Returns `true` if the token is a lifetime.
-    crate fn is_lifetime(&self) -> bool {
+    pub fn is_lifetime(&self) -> bool {
         self.lifetime().is_some()
     }
 
     /// Returns `true` if the token is a identifier whose name is the given
     /// string slice.
-    crate fn is_ident_named(&self, name: Symbol) -> bool {
+    pub fn is_ident_named(&self, name: Symbol) -> bool {
         self.ident().map_or(false, |(ident, _)| ident.name == name)
     }
 
@@ -469,7 +469,7 @@ impl Token {
     /// Would `maybe_whole_expr` in `parser.rs` return `Ok(..)`?
     /// That is, is this a pre-parsed expression dropped into the token stream
     /// (which happens while parsing the result of macro expansion)?
-    crate fn is_whole_expr(&self) -> bool {
+    pub fn is_whole_expr(&self) -> bool {
         if let Interpolated(ref nt) = self.kind {
             if let NtExpr(_) | NtLiteral(_) | NtPath(_) | NtIdent(..) | NtBlock(_) = **nt {
                 return true;
@@ -480,16 +480,16 @@ impl Token {
     }
 
     /// Returns `true` if the token is either the `mut` or `const` keyword.
-    crate fn is_mutability(&self) -> bool {
+    pub fn is_mutability(&self) -> bool {
         self.is_keyword(kw::Mut) ||
         self.is_keyword(kw::Const)
     }
 
-    crate fn is_qpath_start(&self) -> bool {
+    pub fn is_qpath_start(&self) -> bool {
         self == &Lt || self == &BinOp(Shl)
     }
 
-    crate fn is_path_start(&self) -> bool {
+    pub fn is_path_start(&self) -> bool {
         self == &ModSep || self.is_qpath_start() || self.is_path() ||
         self.is_path_segment_keyword() || self.is_ident() && !self.is_reserved_ident()
     }
@@ -499,23 +499,23 @@ impl Token {
         self.is_non_raw_ident_where(|id| id.name == kw)
     }
 
-    crate fn is_path_segment_keyword(&self) -> bool {
+    pub fn is_path_segment_keyword(&self) -> bool {
         self.is_non_raw_ident_where(ast::Ident::is_path_segment_keyword)
     }
 
     // Returns true for reserved identifiers used internally for elided lifetimes,
     // unnamed method parameters, crate root module, error recovery etc.
-    crate fn is_special_ident(&self) -> bool {
+    pub fn is_special_ident(&self) -> bool {
         self.is_non_raw_ident_where(ast::Ident::is_special)
     }
 
     /// Returns `true` if the token is a keyword used in the language.
-    crate fn is_used_keyword(&self) -> bool {
+    pub fn is_used_keyword(&self) -> bool {
         self.is_non_raw_ident_where(ast::Ident::is_used_keyword)
     }
 
     /// Returns `true` if the token is a keyword reserved for possible future use.
-    crate fn is_unused_keyword(&self) -> bool {
+    pub fn is_unused_keyword(&self) -> bool {
         self.is_non_raw_ident_where(ast::Ident::is_unused_keyword)
     }
 
@@ -525,7 +525,7 @@ impl Token {
     }
 
     /// Returns `true` if the token is the identifier `true` or `false`.
-    crate fn is_bool_lit(&self) -> bool {
+    pub fn is_bool_lit(&self) -> bool {
         self.is_non_raw_ident_where(|id| id.name.is_bool_lit())
     }
 
@@ -537,7 +537,7 @@ impl Token {
         }
     }
 
-    crate fn glue(&self, joint: &Token) -> Option<Token> {
+    pub fn glue(&self, joint: &Token) -> Option<Token> {
         let kind = match self.kind {
             Eq => match joint.kind {
                 Eq => EqEq,
diff --git a/src/libsyntax/util/comments.rs b/src/libsyntax/util/comments.rs
index ef9226a8879..5e9b7bf8322 100644
--- a/src/libsyntax/util/comments.rs
+++ b/src/libsyntax/util/comments.rs
@@ -32,14 +32,14 @@ pub struct Comment {
     pub pos: BytePos,
 }
 
-crate fn is_line_doc_comment(s: &str) -> bool {
+pub fn is_line_doc_comment(s: &str) -> bool {
     let res = (s.starts_with("///") && *s.as_bytes().get(3).unwrap_or(&b' ') != b'/') ||
               s.starts_with("//!");
     debug!("is {:?} a doc comment? {}", s, res);
     res
 }
 
-crate fn is_block_doc_comment(s: &str) -> bool {
+pub fn is_block_doc_comment(s: &str) -> bool {
     // Prevent `/**/` from being parsed as a doc comment
     let res = ((s.starts_with("/**") && *s.as_bytes().get(3).unwrap_or(&b' ') != b'*') ||
                s.starts_with("/*!")) && s.len() >= 5;
diff --git a/src/libsyntax/util/literal.rs b/src/libsyntax/util/literal.rs
index d4c9b7850c5..af7afab6b9b 100644
--- a/src/libsyntax/util/literal.rs
+++ b/src/libsyntax/util/literal.rs
@@ -14,7 +14,7 @@ use rustc_lexer::unescape::{unescape_raw_str, unescape_raw_byte_str};
 
 use std::ascii;
 
-crate enum LitError {
+pub enum LitError {
     NotLiteral,
     LexerError,
     InvalidSuffix,
@@ -185,12 +185,12 @@ impl LitKind {
 
 impl Lit {
     /// Converts literal token into an AST literal.
-    crate fn from_lit_token(token: token::Lit, span: Span) -> Result<Lit, LitError> {
+    pub fn from_lit_token(token: token::Lit, span: Span) -> Result<Lit, LitError> {
         Ok(Lit { token, kind: LitKind::from_lit_token(token)?, span })
     }
 
     /// Converts arbitrary token into an AST literal.
-    crate fn from_token(token: &Token) -> Result<Lit, LitError> {
+    pub fn from_token(token: &Token) -> Result<Lit, LitError> {
         let lit = match token.kind {
             token::Ident(name, false) if name.is_bool_lit() =>
                 token::Lit::new(token::Bool, name, None),
@@ -217,8 +217,8 @@ impl Lit {
         Lit { token: kind.to_lit_token(), kind, span }
     }
 
-    /// Losslessly convert an AST literal into a token tree.
-    crate fn token_tree(&self) -> TokenTree {
+    /// Losslessly convert an AST literal into a token stream.
+    pub fn token_tree(&self) -> TokenTree {
         let token = match self.token.kind {
             token::Bool => token::Ident(self.token.symbol, false),
             _ => token::Literal(self.token),
diff --git a/src/libsyntax/util/parser.rs b/src/libsyntax/util/parser.rs
index edb708d7e97..df72fdc8014 100644
--- a/src/libsyntax/util/parser.rs
+++ b/src/libsyntax/util/parser.rs
@@ -69,7 +69,7 @@ pub enum Fixity {
 
 impl AssocOp {
     /// Creates a new AssocOP from a token
-    crate fn from_token(t: &Token) -> Option<AssocOp> {
+    pub fn from_token(t: &Token) -> Option<AssocOp> {
         use AssocOp::*;
         match t.kind {
             token::BinOpEq(k) => Some(AssignOp(k)),
@@ -358,7 +358,7 @@ impl ExprPrecedence {
 }
 
 /// In `let p = e`, operators with precedence `<=` this one requires parenthesis in `e`.
-crate fn prec_let_scrutinee_needs_par() -> usize {
+pub fn prec_let_scrutinee_needs_par() -> usize {
     AssocOp::LAnd.precedence()
 }
 
diff --git a/src/libsyntax_expand/Cargo.toml b/src/libsyntax_expand/Cargo.toml
index 02c711bc387..653b87f0d82 100644
--- a/src/libsyntax_expand/Cargo.toml
+++ b/src/libsyntax_expand/Cargo.toml
@@ -11,15 +11,12 @@ path = "lib.rs"
 doctest = false
 
 [dependencies]
-bitflags = "1.0"
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 log = "0.4"
-scoped-tls = "1.0"
-lazy_static = "1.0.0"
 syntax_pos = { path = "../libsyntax_pos" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
 rustc_data_structures = { path = "../librustc_data_structures" }
-rustc_index = { path = "../librustc_index" }
 rustc_lexer = { path = "../librustc_lexer" }
+rustc_parse = { path = "../librustc_parse" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 syntax = { path = "../libsyntax" }
diff --git a/src/libsyntax_expand/base.rs b/src/libsyntax_expand/base.rs
index 47835c92659..97ee241d838 100644
--- a/src/libsyntax_expand/base.rs
+++ b/src/libsyntax_expand/base.rs
@@ -1,15 +1,15 @@
 use crate::expand::{self, AstFragment, Invocation};
 
+use rustc_parse::{self, parser, DirectoryOwnership, MACRO_ARGUMENTS};
 use syntax::ast::{self, NodeId, Attribute, Name, PatKind};
 use syntax::attr::{self, HasAttrs, Stability, Deprecation};
 use syntax::source_map::SourceMap;
 use syntax::edition::Edition;
 use syntax::mut_visit::{self, MutVisitor};
-use syntax::parse::{self, parser, DirectoryOwnership};
 use syntax::ptr::P;
 use syntax::sess::ParseSess;
 use syntax::symbol::{kw, sym, Ident, Symbol};
-use syntax::{ThinVec, MACRO_ARGUMENTS};
+use syntax::ThinVec;
 use syntax::token;
 use syntax::tokenstream::{self, TokenStream};
 use syntax::visit::Visitor;
@@ -18,9 +18,9 @@ use errors::{DiagnosticBuilder, DiagnosticId};
 use smallvec::{smallvec, SmallVec};
 use syntax_pos::{FileName, Span, MultiSpan, DUMMY_SP};
 use syntax_pos::hygiene::{AstPass, ExpnId, ExpnData, ExpnKind};
-
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::{self, Lrc};
+
 use std::iter;
 use std::path::PathBuf;
 use std::rc::Rc;
@@ -922,7 +922,7 @@ impl<'a> ExtCtxt<'a> {
         expand::MacroExpander::new(self, true)
     }
     pub fn new_parser_from_tts(&self, stream: TokenStream) -> parser::Parser<'a> {
-        parse::stream_to_parser(self.parse_sess, stream, MACRO_ARGUMENTS)
+        rustc_parse::stream_to_parser(self.parse_sess, stream, MACRO_ARGUMENTS)
     }
     pub fn source_map(&self) -> &'a SourceMap { self.parse_sess.source_map() }
     pub fn parse_sess(&self) -> &'a ParseSess { self.parse_sess }
diff --git a/src/libsyntax_expand/config.rs b/src/libsyntax_expand/config.rs
index 9acb9948926..7b927fb55f9 100644
--- a/src/libsyntax_expand/config.rs
+++ b/src/libsyntax_expand/config.rs
@@ -1,3 +1,4 @@
+use rustc_parse::validate_attr;
 use syntax::attr::HasAttrs;
 use syntax::feature_gate::{
     feature_err,
@@ -10,11 +11,10 @@ use syntax::attr;
 use syntax::ast;
 use syntax::edition::Edition;
 use syntax::mut_visit::*;
-use syntax::parse::{self, validate_attr};
 use syntax::ptr::P;
 use syntax::sess::ParseSess;
-use syntax::symbol::sym;
 use syntax::util::map_in_place::MapInPlace;
+use syntax_pos::symbol::sym;
 
 use errors::Applicability;
 use smallvec::SmallVec;
@@ -113,7 +113,7 @@ impl<'a> StripUnconfigured<'a> {
             return vec![];
         }
 
-        let res = parse::parse_in_attr(self.sess, &attr, |p| p.parse_cfg_attr());
+        let res = rustc_parse::parse_in_attr(self.sess, &attr, |p| p.parse_cfg_attr());
         let (cfg_predicate, expanded_attrs) = match res {
             Ok(result) => result,
             Err(mut e) => {
diff --git a/src/libsyntax_expand/expand.rs b/src/libsyntax_expand/expand.rs
index 1e6c23087d8..b7f6364c2b5 100644
--- a/src/libsyntax_expand/expand.rs
+++ b/src/libsyntax_expand/expand.rs
@@ -6,15 +6,15 @@ use crate::placeholders::{placeholder, PlaceholderExpander};
 use crate::config::StripUnconfigured;
 use crate::configure;
 
+use rustc_parse::DirectoryOwnership;
+use rustc_parse::parser::Parser;
+use rustc_parse::validate_attr;
 use syntax::ast::{self, AttrItem, Block, Ident, LitKind, NodeId, PatKind, Path};
 use syntax::ast::{MacStmtStyle, StmtKind, ItemKind};
 use syntax::attr::{self, HasAttrs};
 use syntax::source_map::respan;
 use syntax::feature_gate::{self, Features, GateIssue, is_builtin_attr, emit_feature_err};
 use syntax::mut_visit::*;
-use syntax::parse::DirectoryOwnership;
-use syntax::parse::parser::Parser;
-use syntax::parse::validate_attr;
 use syntax::print::pprust;
 use syntax::ptr::P;
 use syntax::sess::ParseSess;
diff --git a/src/libsyntax_expand/mbe/macro_parser.rs b/src/libsyntax_expand/mbe/macro_parser.rs
index 80bf27e1a94..0dcb2c39fdc 100644
--- a/src/libsyntax_expand/mbe/macro_parser.rs
+++ b/src/libsyntax_expand/mbe/macro_parser.rs
@@ -76,9 +76,9 @@ use TokenTreeOrTokenTreeSlice::*;
 
 use crate::mbe::{self, TokenTree};
 
+use rustc_parse::Directory;
+use rustc_parse::parser::{Parser, PathStyle};
 use syntax::ast::{Ident, Name};
-use syntax::parse::Directory;
-use syntax::parse::parser::{Parser, PathStyle};
 use syntax::print::pprust;
 use syntax::sess::ParseSess;
 use syntax::symbol::{kw, sym, Symbol};
@@ -652,7 +652,7 @@ pub(super) fn parse(
         directory,
         recurse_into_modules,
         true,
-        syntax::MACRO_ARGUMENTS,
+        rustc_parse::MACRO_ARGUMENTS,
     );
 
     // A queue of possible matcher positions. We initialize it with the matcher position in which
diff --git a/src/libsyntax_expand/mbe/macro_rules.rs b/src/libsyntax_expand/mbe/macro_rules.rs
index a5fc301fbf6..72b7996628a 100644
--- a/src/libsyntax_expand/mbe/macro_rules.rs
+++ b/src/libsyntax_expand/mbe/macro_rules.rs
@@ -8,30 +8,30 @@ use crate::mbe::macro_parser::{Error, Failure, Success};
 use crate::mbe::macro_parser::{MatchedNonterminal, MatchedSeq, NamedParseResult};
 use crate::mbe::transcribe::transcribe;
 
+use rustc_parse::parser::Parser;
+use rustc_parse::Directory;
 use syntax::ast;
 use syntax::attr::{self, TransparencyError};
 use syntax::edition::Edition;
 use syntax::feature_gate::Features;
-use syntax::parse::parser::Parser;
-use syntax::parse::Directory;
 use syntax::print::pprust;
 use syntax::sess::ParseSess;
 use syntax::symbol::{kw, sym, Symbol};
 use syntax::token::{self, NtTT, Token, TokenKind::*};
 use syntax::tokenstream::{DelimSpan, TokenStream};
+use syntax_pos::hygiene::Transparency;
+use syntax_pos::Span;
 
 use errors::{DiagnosticBuilder, FatalError};
 use log::debug;
-use syntax_pos::hygiene::Transparency;
-use syntax_pos::Span;
 
 use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::sync::Lrc;
 use std::borrow::Cow;
 use std::collections::hash_map::Entry;
 use std::{mem, slice};
 
 use errors::Applicability;
-use rustc_data_structures::sync::Lrc;
 
 const VALID_FRAGMENT_NAMES_MSG: &str = "valid fragment specifiers are \
                                         `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, \
diff --git a/src/libsyntax_expand/parse/lexer/tests.rs b/src/libsyntax_expand/parse/lexer/tests.rs
index 3d5726fa601..d8a1c359c95 100644
--- a/src/libsyntax_expand/parse/lexer/tests.rs
+++ b/src/libsyntax_expand/parse/lexer/tests.rs
@@ -1,18 +1,18 @@
 use crate::config::process_configure_mod;
 
 use rustc_data_structures::sync::Lrc;
+use rustc_parse::lexer::StringReader;
 use syntax::token::{self, Token, TokenKind};
 use syntax::sess::ParseSess;
 use syntax::source_map::{SourceMap, FilePathMapping};
 use syntax::util::comments::is_doc_comment;
 use syntax::with_default_globals;
-use syntax::parse::lexer::StringReader;
 use syntax_pos::symbol::Symbol;
+use syntax_pos::{BytePos, Span};
 
 use errors::{Handler, emitter::EmitterWriter};
 use std::io;
 use std::path::PathBuf;
-use syntax_pos::{BytePos, Span};
 
 fn mk_sess(sm: Lrc<SourceMap>) -> ParseSess {
     let emitter = EmitterWriter::new(
diff --git a/src/libsyntax_expand/parse/tests.rs b/src/libsyntax_expand/parse/tests.rs
index 01739809f7f..60911617995 100644
--- a/src/libsyntax_expand/parse/tests.rs
+++ b/src/libsyntax_expand/parse/tests.rs
@@ -1,6 +1,7 @@
 use crate::config::process_configure_mod;
 use crate::tests::{matches_codepattern, string_to_stream, with_error_checking_parse};
 
+use rustc_parse::new_parser_from_source_str;
 use syntax::ast::{self, Name, PatKind};
 use syntax::attr::first_attr_value_str_by_name;
 use syntax::sess::ParseSess;
@@ -12,7 +13,6 @@ use syntax::symbol::{kw, sym};
 use syntax::tokenstream::{DelimSpan, TokenTree, TokenStream};
 use syntax::visit;
 use syntax::with_default_globals;
-use syntax::parse::new_parser_from_source_str;
 use syntax_pos::{Span, BytePos, Pos, FileName};
 use errors::PResult;
 
diff --git a/src/libsyntax_expand/proc_macro.rs b/src/libsyntax_expand/proc_macro.rs
index 51c368bbaa6..db981fae5c2 100644
--- a/src/libsyntax_expand/proc_macro.rs
+++ b/src/libsyntax_expand/proc_macro.rs
@@ -4,7 +4,6 @@ use crate::proc_macro_server;
 use syntax::ast::{self, ItemKind, Attribute, Mac};
 use syntax::attr::{mark_used, mark_known};
 use syntax::errors::{Applicability, FatalError};
-use syntax::parse;
 use syntax::symbol::sym;
 use syntax::token;
 use syntax::tokenstream::{self, TokenStream};
@@ -135,7 +134,11 @@ impl MultiItemModifier for ProcMacroDerive {
         let error_count_before = ecx.parse_sess.span_diagnostic.err_count();
         let msg = "proc-macro derive produced unparseable tokens";
 
-        let mut parser = parse::stream_to_parser(ecx.parse_sess, stream, Some("proc-macro derive"));
+        let mut parser = rustc_parse::stream_to_parser(
+            ecx.parse_sess,
+            stream,
+            Some("proc-macro derive"),
+        );
         let mut items = vec![];
 
         loop {
@@ -200,7 +203,7 @@ crate fn collect_derives(cx: &mut ExtCtxt<'_>, attrs: &mut Vec<ast::Attribute>)
             if attr.get_normal_item().tokens.is_empty() {
                 return Ok(Vec::new());
             }
-            parse::parse_in_attr(cx.parse_sess, attr, |p| p.parse_derive_paths())
+            rustc_parse::parse_in_attr(cx.parse_sess, attr, |p| p.parse_derive_paths())
         };
 
         match parse_derive_paths(attr) {
diff --git a/src/libsyntax_expand/proc_macro_server.rs b/src/libsyntax_expand/proc_macro_server.rs
index e96b6092787..43a9d4169f6 100644
--- a/src/libsyntax_expand/proc_macro_server.rs
+++ b/src/libsyntax_expand/proc_macro_server.rs
@@ -1,17 +1,17 @@
 use crate::base::ExtCtxt;
 
+use rustc_parse::{parse_stream_from_source_str, nt_to_tokenstream};
 use syntax::ast;
-use syntax::parse;
 use syntax::util::comments;
 use syntax::print::pprust;
 use syntax::sess::ParseSess;
 use syntax::token;
 use syntax::tokenstream::{self, DelimSpan, IsJoint::*, TokenStream, TreeAndJoint};
+use syntax_pos::{BytePos, FileName, MultiSpan, Pos, SourceFile, Span};
+use syntax_pos::symbol::{kw, sym, Symbol};
 
 use errors::Diagnostic;
 use rustc_data_structures::sync::Lrc;
-use syntax_pos::{BytePos, FileName, MultiSpan, Pos, SourceFile, Span};
-use syntax_pos::symbol::{kw, sym, Symbol};
 
 use pm::{Delimiter, Level, LineColumn, Spacing};
 use pm::bridge::{server, TokenTree};
@@ -178,7 +178,7 @@ impl FromInternal<(TreeAndJoint, &'_ ParseSess, &'_ mut Vec<Self>)>
             }
 
             Interpolated(nt) => {
-                let stream = parse::nt_to_tokenstream(&nt, sess, span);
+                let stream = nt_to_tokenstream(&nt, sess, span);
                 TokenTree::Group(Group {
                     delimiter: Delimiter::None,
                     stream,
@@ -402,7 +402,7 @@ impl server::TokenStream for Rustc<'_> {
         stream.is_empty()
     }
     fn from_str(&mut self, src: &str) -> Self::TokenStream {
-        parse::parse_stream_from_source_str(
+        parse_stream_from_source_str(
             FileName::proc_macro_source_code(src),
             src.to_string(),
             self.sess,
diff --git a/src/libsyntax_expand/tests.rs b/src/libsyntax_expand/tests.rs
index 461d9a43954..2683620e845 100644
--- a/src/libsyntax_expand/tests.rs
+++ b/src/libsyntax_expand/tests.rs
@@ -1,10 +1,10 @@
 use crate::config::process_configure_mod;
+use rustc_parse::{source_file_to_stream, new_parser_from_source_str, parser::Parser};
 use syntax::ast;
 use syntax::tokenstream::TokenStream;
 use syntax::sess::ParseSess;
 use syntax::source_map::{SourceMap, FilePathMapping};
 use syntax::with_default_globals;
-use syntax::parse::{source_file_to_stream, new_parser_from_source_str, parser::Parser};
 use syntax_pos::{BytePos, Span, MultiSpan};
 
 use errors::emitter::EmitterWriter;
diff --git a/src/libsyntax_ext/Cargo.toml b/src/libsyntax_ext/Cargo.toml
index 703d51e1c4c..5ae8b3a3e0c 100644
--- a/src/libsyntax_ext/Cargo.toml
+++ b/src/libsyntax_ext/Cargo.toml
@@ -14,6 +14,7 @@ errors = { path = "../librustc_errors", package = "rustc_errors" }
 fmt_macros = { path = "../libfmt_macros" }
 log = "0.4"
 rustc_data_structures = { path = "../librustc_data_structures" }
+rustc_parse = { path = "../librustc_parse" }
 rustc_target = { path = "../librustc_target" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 syntax = { path = "../libsyntax" }
diff --git a/src/libsyntax_ext/assert.rs b/src/libsyntax_ext/assert.rs
index a15423b7ad8..c4f3c03813f 100644
--- a/src/libsyntax_ext/assert.rs
+++ b/src/libsyntax_ext/assert.rs
@@ -1,13 +1,13 @@
 use errors::{Applicability, DiagnosticBuilder};
 
+use rustc_parse::parser::Parser;
 use syntax::ast::{self, *};
-use syntax_expand::base::*;
 use syntax::token::{self, TokenKind};
-use syntax::parse::parser::Parser;
 use syntax::print::pprust;
 use syntax::ptr::P;
 use syntax::symbol::{sym, Symbol};
 use syntax::tokenstream::{TokenStream, TokenTree};
+use syntax_expand::base::*;
 use syntax_pos::{Span, DUMMY_SP};
 
 pub fn expand_assert<'cx>(
diff --git a/src/libsyntax_ext/cmdline_attrs.rs b/src/libsyntax_ext/cmdline_attrs.rs
index 171f2405573..5c3009c432c 100644
--- a/src/libsyntax_ext/cmdline_attrs.rs
+++ b/src/libsyntax_ext/cmdline_attrs.rs
@@ -2,7 +2,6 @@
 
 use syntax::ast::{self, AttrItem, AttrStyle};
 use syntax::attr::mk_attr;
-use syntax::parse;
 use syntax::token;
 use syntax::sess::ParseSess;
 use syntax_expand::panictry;
@@ -10,7 +9,7 @@ use syntax_pos::FileName;
 
 pub fn inject(mut krate: ast::Crate, parse_sess: &ParseSess, attrs: &[String]) -> ast::Crate {
     for raw_attr in attrs {
-        let mut parser = parse::new_parser_from_source_str(
+        let mut parser = rustc_parse::new_parser_from_source_str(
             parse_sess,
             FileName::cli_crate_attr_source_code(&raw_attr),
             raw_attr.clone(),
diff --git a/src/libsyntax_ext/source_util.rs b/src/libsyntax_ext/source_util.rs
index 7e47b40714d..120b533a69b 100644
--- a/src/libsyntax_ext/source_util.rs
+++ b/src/libsyntax_ext/source_util.rs
@@ -1,13 +1,13 @@
-use syntax_expand::panictry;
-use syntax_expand::base::{self, *};
+use rustc_parse::{self, DirectoryOwnership, new_sub_parser_from_file, parser::Parser};
 use syntax::ast;
-use syntax::parse::{self, DirectoryOwnership};
 use syntax::print::pprust;
 use syntax::ptr::P;
 use syntax::symbol::Symbol;
 use syntax::token;
 use syntax::tokenstream::TokenStream;
 use syntax::early_buffered_lints::BufferedEarlyLintId;
+use syntax_expand::panictry;
+use syntax_expand::base::{self, *};
 
 use smallvec::SmallVec;
 use syntax_pos::{self, Pos, Span};
@@ -85,10 +85,10 @@ pub fn expand_include<'cx>(cx: &'cx mut ExtCtxt<'_>, sp: Span, tts: TokenStream)
         },
     };
     let directory_ownership = DirectoryOwnership::Owned { relative: None };
-    let p = parse::new_sub_parser_from_file(cx.parse_sess(), &file, directory_ownership, None, sp);
+    let p = new_sub_parser_from_file(cx.parse_sess(), &file, directory_ownership, None, sp);
 
     struct ExpandResult<'a> {
-        p: parse::parser::Parser<'a>,
+        p: Parser<'a>,
     }
     impl<'a> base::MacResult for ExpandResult<'a> {
         fn make_expr(mut self: Box<ExpandResult<'a>>) -> Option<P<ast::Expr>> {
diff --git a/src/libsyntax_ext/util.rs b/src/libsyntax_ext/util.rs
index c8f0eb4ad25..e59daab1770 100644
--- a/src/libsyntax_ext/util.rs
+++ b/src/libsyntax_ext/util.rs
@@ -1,7 +1,7 @@
+use rustc_parse::validate_attr;
 use syntax_pos::Symbol;
 use syntax::ast::MetaItem;
 use syntax::attr::AttributeTemplate;
-use syntax::parse::validate_attr;
 use syntax_expand::base::ExtCtxt;
 
 pub fn check_builtin_macro_attribute(ecx: &ExtCtxt<'_>, meta_item: &MetaItem, name: Symbol) {
diff --git a/src/test/ui-fulldeps/ast_stmt_expr_attr.rs b/src/test/ui-fulldeps/ast_stmt_expr_attr.rs
index 3d2181d4e37..0bf17302b06 100644
--- a/src/test/ui-fulldeps/ast_stmt_expr_attr.rs
+++ b/src/test/ui-fulldeps/ast_stmt_expr_attr.rs
@@ -7,9 +7,13 @@
 
 extern crate syntax;
 extern crate syntax_expand;
+extern crate rustc_parse;
 extern crate rustc_errors;
 
 use rustc_errors::PResult;
+use rustc_parse::parser::attr::*;
+use rustc_parse::new_parser_from_source_str;
+use rustc_parse::parser::Parser;
 use syntax::ast::*;
 use syntax::attr::*;
 use syntax::ast;
@@ -17,9 +21,6 @@ use syntax::sess::ParseSess;
 use syntax::source_map::{FilePathMapping, FileName};
 use syntax::ptr::P;
 use syntax::print::pprust;
-use syntax::parse::parser::attr::*;
-use syntax::parse::new_parser_from_source_str;
-use syntax::parse::parser::Parser;
 use syntax::token;
 use syntax_expand::config::process_configure_mod;
 use std::fmt;
diff --git a/src/test/ui-fulldeps/mod_dir_path_canonicalized.rs b/src/test/ui-fulldeps/mod_dir_path_canonicalized.rs
index 472440e2e14..2411b9634c3 100644
--- a/src/test/ui-fulldeps/mod_dir_path_canonicalized.rs
+++ b/src/test/ui-fulldeps/mod_dir_path_canonicalized.rs
@@ -6,11 +6,12 @@
 
 extern crate syntax;
 extern crate syntax_expand;
+extern crate rustc_parse;
 
+use rustc_parse::new_parser_from_file;
 use std::path::Path;
 use syntax::sess::ParseSess;
 use syntax::source_map::FilePathMapping;
-use syntax::parse::new_parser_from_file;
 use syntax_expand::config::process_configure_mod;
 
 #[path = "mod_dir_simple/test.rs"]
diff --git a/src/test/ui-fulldeps/pprust-expr-roundtrip.rs b/src/test/ui-fulldeps/pprust-expr-roundtrip.rs
index 99da605f357..5da0297f645 100644
--- a/src/test/ui-fulldeps/pprust-expr-roundtrip.rs
+++ b/src/test/ui-fulldeps/pprust-expr-roundtrip.rs
@@ -22,14 +22,15 @@
 extern crate rustc_data_structures;
 extern crate syntax;
 extern crate syntax_expand;
+extern crate rustc_parse;
 
 use rustc_data_structures::thin_vec::ThinVec;
+use rustc_parse::new_parser_from_source_str;
 use syntax::ast::*;
 use syntax::sess::ParseSess;
 use syntax::source_map::{Spanned, DUMMY_SP, FileName};
 use syntax::source_map::FilePathMapping;
 use syntax::mut_visit::{self, MutVisitor, visit_clobber};
-use syntax::parse::new_parser_from_source_str;
 use syntax::print::pprust;
 use syntax::ptr::P;
 use syntax_expand::config::process_configure_mod;
-- 
cgit 1.4.1-3-g733a5