move from non zero impls to `libcore/convert/num.rs`

52 files changed, 768 insertions, 19874 deletions

diff --git a/src/libsyntax/Cargo.toml b/src/libsyntax/Cargo.toml
index 3e17e7949ea..8a00bcbfe17 100644
--- a/src/libsyntax/Cargo.toml
+++ b/src/libsyntax/Cargo.toml
@@ -18,6 +18,10 @@ 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_feature = { path = "../librustc_feature" }
 rustc_index = { path = "../librustc_index" }
 rustc_lexer = { path = "../librustc_lexer" }
+rustc_macros = { path = "../librustc_macros" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
+rustc_error_codes = { path = "../librustc_error_codes" }
+rustc_session = { path = "../librustc_session" }
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index b57d2238991..92ba071a03d 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -27,20 +27,19 @@ pub use syntax_pos::symbol::{Ident, Symbol as Name};
 use crate::ptr::P;
 use crate::source_map::{dummy_spanned, respan, Spanned};
 use crate::token::{self, DelimToken};
-use crate::tokenstream::TokenStream;
+use crate::tokenstream::{TokenStream, TokenTree, DelimSpan};
 
 use syntax_pos::symbol::{kw, sym, Symbol};
-use syntax_pos::{Span, DUMMY_SP, ExpnId};
+use syntax_pos::{Span, DUMMY_SP};
 
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 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_macros::HashStable_Generic;
 
-#[cfg(target_arch = "x86_64")]
-use rustc_data_structures::static_assert_size;
-
+use std::iter;
 use std::fmt;
 
 #[cfg(test)]
@@ -56,7 +55,7 @@ mod tests;
 /// ```
 ///
 /// `'outer` is a label.
-#[derive(Clone, RustcEncodable, RustcDecodable, Copy)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Copy, HashStable_Generic)]
 pub struct Label {
     pub ident: Ident,
 }
@@ -114,6 +113,15 @@ impl PartialEq<Symbol> for Path {
     }
 }
 
+impl<CTX> HashStable<CTX> for Path {
+    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
+        self.segments.len().hash_stable(hcx, hasher);
+        for segment in &self.segments {
+            segment.ident.name.hash_stable(hcx, hasher);
+        }
+    }
+}
+
 impl Path {
     // Convert a span and an identifier to the corresponding
     // one-segment path.
@@ -259,46 +267,7 @@ impl ParenthesizedArgs {
     }
 }
 
-// hack to ensure that we don't try to access the private parts of `NodeId` in this module
-mod node_id_inner {
-    use rustc_index::vec::Idx;
-    rustc_index::newtype_index! {
-        pub struct NodeId {
-            ENCODABLE = custom
-            DEBUG_FORMAT = "NodeId({})"
-        }
-    }
-}
-
-pub use node_id_inner::NodeId;
-
-impl NodeId {
-    pub fn placeholder_from_expn_id(expn_id: ExpnId) -> Self {
-        NodeId::from_u32(expn_id.as_u32())
-    }
-
-    pub fn placeholder_to_expn_id(self) -> ExpnId {
-        ExpnId::from_u32(self.as_u32())
-    }
-}
-
-impl fmt::Display for NodeId {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(&self.as_u32(), f)
-    }
-}
-
-impl rustc_serialize::UseSpecializedEncodable for NodeId {
-    fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
-        s.emit_u32(self.as_u32())
-    }
-}
-
-impl rustc_serialize::UseSpecializedDecodable for NodeId {
-    fn default_decode<D: Decoder>(d: &mut D) -> Result<NodeId, D::Error> {
-        d.read_u32().map(NodeId::from_u32)
-    }
-}
+pub use rustc_session::node_id::NodeId;
 
 /// `NodeId` used to represent the root of the crate.
 pub const CRATE_NODE_ID: NodeId = NodeId::from_u32_const(0);
@@ -461,9 +430,7 @@ pub struct WhereEqPredicate {
     pub rhs_ty: P<Ty>,
 }
 
-/// The set of `MetaItem`s that define the compilation environment of the crate,
-/// used to drive conditional compilation.
-pub type CrateConfig = FxHashSet<(Name, Option<Symbol>)>;
+pub use rustc_session::parse::CrateConfig;
 
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Crate {
@@ -475,7 +442,7 @@ pub struct Crate {
 /// Possible values inside of compile-time attribute lists.
 ///
 /// E.g., the '..' in `#[name(..)]`.
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub enum NestedMetaItem {
     /// A full MetaItem, for recursive meta items.
     MetaItem(MetaItem),
@@ -488,7 +455,7 @@ pub enum NestedMetaItem {
 /// A spanned compile-time attribute item.
 ///
 /// E.g., `#[test]`, `#[derive(..)]`, `#[rustfmt::skip]` or `#[feature = "foo"]`.
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub struct MetaItem {
     pub path: Path,
     pub kind: MetaItemKind,
@@ -498,7 +465,7 @@ pub struct MetaItem {
 /// A compile-time attribute item.
 ///
 /// E.g., `#[test]`, `#[derive(..)]` or `#[feature = "foo"]`.
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub enum MetaItemKind {
     /// Word meta item.
     ///
@@ -537,7 +504,7 @@ 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,
@@ -725,14 +692,52 @@ pub enum PatKind {
     Mac(Mac),
 }
 
-#[derive(
-    Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable, Debug, Copy,
-)]
+#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
+         RustcEncodable, RustcDecodable, Debug, Copy, HashStable_Generic)]
 pub enum Mutability {
     Mutable,
     Immutable,
 }
 
+impl Mutability {
+    /// Returns `MutMutable` only if both `self` and `other` are mutable.
+    pub fn and(self, other: Self) -> Self {
+        match self {
+            Mutability::Mutable => other,
+            Mutability::Immutable => Mutability::Immutable,
+        }
+    }
+
+    pub fn invert(self) -> Self {
+        match self {
+            Mutability::Mutable => Mutability::Immutable,
+            Mutability::Immutable => Mutability::Mutable,
+        }
+    }
+
+    pub fn prefix_str(&self) -> &'static str {
+        match self {
+            Mutability::Mutable => "mut ",
+            Mutability::Immutable => "",
+        }
+    }
+}
+
+/// The kind of borrow in an `AddrOf` expression,
+/// e.g., `&place` or `&raw const place`.
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+#[derive(RustcEncodable, RustcDecodable, HashStable_Generic)]
+pub enum BorrowKind {
+    /// A raw borrow, `&raw const $expr` or `&raw mut $expr`.
+    /// The resulting type is either `*const T` or `*mut T`
+    /// where `T = typeof($expr)`.
+    Ref,
+    /// A normal borrow, `&$expr` or `&mut $expr`.
+    /// The resulting type is either `&'a T` or `&'a mut T`
+    /// where `T = typeof($expr)` and `'a` is some lifetime.
+    Raw,
+}
+
 #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, Copy)]
 pub enum BinOpKind {
     /// The `+` operator (addition)
@@ -961,12 +966,12 @@ pub struct Arm {
 /// Access of a named (e.g., `obj.foo`) or unnamed (e.g., `obj.0`) struct field.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Field {
+    pub attrs: ThinVec<Attribute>,
+    pub id: NodeId,
+    pub span: Span,
     pub ident: Ident,
     pub expr: P<Expr>,
-    pub span: Span,
     pub is_shorthand: bool,
-    pub attrs: ThinVec<Attribute>,
-    pub id: NodeId,
     pub is_placeholder: bool,
 }
 
@@ -1004,7 +1009,7 @@ pub struct Expr {
 
 // `Expr` is used a lot. Make sure it doesn't unintentionally get bigger.
 #[cfg(target_arch = "x86_64")]
-static_assert_size!(Expr, 96);
+rustc_data_structures::static_assert_size!(Expr, 96);
 
 impl Expr {
     /// Returns `true` if this expression would be valid somewhere that expects a value;
@@ -1031,7 +1036,7 @@ 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 +1047,7 @@ 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()),
@@ -1050,7 +1055,7 @@ impl Expr {
 
             ExprKind::Paren(expr) => expr.to_ty().map(TyKind::Paren)?,
 
-            ExprKind::AddrOf(mutbl, expr) => expr
+            ExprKind::AddrOf(BorrowKind::Ref, mutbl, expr) => expr
                 .to_ty()
                 .map(|ty| TyKind::Rptr(None, MutTy { ty, mutbl: *mutbl }))?,
 
@@ -1241,8 +1246,8 @@ pub enum ExprKind {
     /// Optionally "qualified" (e.g., `<Vec<T> as SomeTrait>::SomeType`).
     Path(Option<QSelf>, Path),
 
-    /// A referencing operation (`&a` or `&mut a`).
-    AddrOf(Mutability, P<Expr>),
+    /// A referencing operation (`&a`, `&mut a`, `&raw const a` or `&raw mut a`).
+    AddrOf(BorrowKind, Mutability, P<Expr>),
     /// A `break`, with an optional label to break, and an optional expression.
     Break(Option<Label>, Option<P<Expr>>),
     /// A `continue`, with an optional label.
@@ -1307,7 +1312,7 @@ pub struct QSelf {
 }
 
 /// A capture clause used in closures and `async` blocks.
-#[derive(Clone, Copy, PartialEq, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, Copy, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub enum CaptureBy {
     /// `move |x| y + x`.
     Value,
@@ -1315,41 +1320,100 @@ pub enum CaptureBy {
     Ref,
 }
 
-/// The movability of a generator / closure literal.
-#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, Copy)]
+/// The movability of a generator / closure literal:
+/// whether a generator contains self-references, causing it to be `!Unpin`.
+#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
+         RustcEncodable, RustcDecodable, Debug, Copy, HashStable_Generic)]
 pub enum Movability {
+    /// May contain self-references, `!Unpin`.
     Static,
+    /// Must not contain self-references, `Unpin`.
     Movable,
 }
 
-/// Represents a macro invocation. The `Path` indicates which macro
-/// is being invoked, and the vector of token-trees contains the source
-/// of the macro invocation.
-///
-/// N.B., the additional ident for a `macro_rules`-style macro is actually
-/// stored in the enclosing item.
+/// Represents a macro invocation. The `path` indicates which macro
+/// is being invoked, and the `args` are arguments passed to it.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Mac {
     pub path: Path,
-    pub delim: MacDelimiter,
-    pub tts: TokenStream,
-    pub span: Span,
+    pub args: P<MacArgs>,
     pub prior_type_ascription: Option<(Span, bool)>,
 }
 
-#[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Debug)]
+impl Mac {
+    pub fn span(&self) -> Span {
+        self.path.span.to(self.args.span().unwrap_or(self.path.span))
+    }
+}
+
+/// Arguments passed to an attribute or a function-like macro.
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
+pub enum MacArgs {
+    /// No arguments - `#[attr]`.
+    Empty,
+    /// Delimited arguments - `#[attr()/[]/{}]` or `mac!()/[]/{}`.
+    Delimited(DelimSpan, MacDelimiter, TokenStream),
+    /// Arguments of a key-value attribute - `#[attr = "value"]`.
+    Eq(
+        /// Span of the `=` token.
+        Span,
+        /// Token stream of the "value".
+        TokenStream,
+    ),
+}
+
+impl MacArgs {
+    pub fn delim(&self) -> DelimToken {
+        match self {
+            MacArgs::Delimited(_, delim, _) => delim.to_token(),
+            MacArgs::Empty | MacArgs::Eq(..) => token::NoDelim,
+        }
+    }
+
+    pub fn span(&self) -> Option<Span> {
+        match *self {
+            MacArgs::Empty => None,
+            MacArgs::Delimited(dspan, ..) => Some(dspan.entire()),
+            MacArgs::Eq(eq_span, ref tokens) => Some(eq_span.to(tokens.span().unwrap_or(eq_span))),
+        }
+    }
+
+    /// Tokens inside the delimiters or after `=`.
+    /// Proc macros see these tokens, for example.
+    pub fn inner_tokens(&self) -> TokenStream {
+        match self {
+            MacArgs::Empty => TokenStream::default(),
+            MacArgs::Delimited(.., tokens) |
+            MacArgs::Eq(.., tokens) => tokens.clone(),
+        }
+    }
+
+    /// Tokens together with the delimiters or `=`.
+    /// Use of this method generally means that something suboptimal or hacky is happening.
+    pub fn outer_tokens(&self) -> TokenStream {
+        match *self {
+            MacArgs::Empty => TokenStream::default(),
+            MacArgs::Delimited(dspan, delim, ref tokens) =>
+                TokenTree::Delimited(dspan, delim.to_token(), tokens.clone()).into(),
+            MacArgs::Eq(eq_span, ref tokens) => iter::once(TokenTree::token(token::Eq, eq_span))
+                                                .chain(tokens.trees()).collect(),
+        }
+    }
+
+    /// Whether a macro with these arguments needs a semicolon
+    /// when used as a standalone item or statement.
+    pub fn need_semicolon(&self) -> bool {
+        !matches!(self, MacArgs::Delimited(_, MacDelimiter::Brace ,_))
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub enum MacDelimiter {
     Parenthesis,
     Bracket,
     Brace,
 }
 
-impl Mac {
-    pub fn stream(&self) -> TokenStream {
-        self.tts.clone()
-    }
-}
-
 impl MacDelimiter {
     crate fn to_token(self) -> DelimToken {
         match self {
@@ -1358,24 +1422,27 @@ impl MacDelimiter {
             MacDelimiter::Brace => DelimToken::Brace,
         }
     }
+
+    pub fn from_token(delim: DelimToken) -> Option<MacDelimiter> {
+        match delim {
+            token::Paren => Some(MacDelimiter::Parenthesis),
+            token::Bracket => Some(MacDelimiter::Bracket),
+            token::Brace => Some(MacDelimiter::Brace),
+            token::NoDelim => None,
+        }
+    }
 }
 
 /// Represents a macro definition.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct MacroDef {
-    pub tokens: TokenStream,
+    pub body: P<MacArgs>,
     /// `true` if macro was defined with `macro_rules`.
     pub legacy: bool,
 }
 
-impl MacroDef {
-    pub fn stream(&self) -> TokenStream {
-        self.tokens.clone().into()
-    }
-}
-
 // Clippy uses Hash and PartialEq
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug, Copy, Hash, PartialEq)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug, Copy, Hash, PartialEq, HashStable_Generic)]
 pub enum StrStyle {
     /// A regular string, like `"foo"`.
     Cooked,
@@ -1386,7 +1453,7 @@ pub enum StrStyle {
 }
 
 /// An AST literal.
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub struct Lit {
     /// The original literal token as written in source code.
     pub token: token::Lit,
@@ -1397,9 +1464,36 @@ pub struct Lit {
     pub span: Span,
 }
 
+/// Same as `Lit`, but restricted to string literals.
+#[derive(Clone, Copy, RustcEncodable, RustcDecodable, Debug)]
+pub struct StrLit {
+    /// The original literal token as written in source code.
+    pub style: StrStyle,
+    pub symbol: Symbol,
+    pub suffix: Option<Symbol>,
+    pub span: Span,
+    /// The unescaped "semantic" representation of the literal lowered from the original token.
+    /// FIXME: Remove this and only create the semantic representation during lowering to HIR.
+    pub symbol_unescaped: Symbol,
+}
+
+impl StrLit {
+    crate fn as_lit(&self) -> Lit {
+        let token_kind = match self.style {
+            StrStyle::Cooked => token::Str,
+            StrStyle::Raw(n) => token::StrRaw(n),
+        };
+        Lit {
+            token: token::Lit::new(token_kind, self.symbol, self.suffix),
+            span: self.span,
+            kind: LitKind::Str(self.symbol_unescaped, self.style),
+        }
+    }
+}
+
 // Clippy uses Hash and PartialEq
 /// Type of the integer literal based on provided suffix.
-#[derive(Clone, Copy, RustcEncodable, RustcDecodable, Debug, Hash, PartialEq)]
+#[derive(Clone, Copy, RustcEncodable, RustcDecodable, Debug, Hash, PartialEq, HashStable_Generic)]
 pub enum LitIntType {
     /// e.g. `42_i32`.
     Signed(IntTy),
@@ -1410,7 +1504,7 @@ pub enum LitIntType {
 }
 
 /// Type of the float literal based on provided suffix.
-#[derive(Clone, Copy, RustcEncodable, RustcDecodable, Debug, Hash, PartialEq)]
+#[derive(Clone, Copy, RustcEncodable, RustcDecodable, Debug, Hash, PartialEq, HashStable_Generic)]
 pub enum LitFloatType {
     /// A float literal with a suffix (`1f32` or `1E10f32`).
     Suffixed(FloatTy),
@@ -1422,7 +1516,7 @@ pub enum LitFloatType {
 ///
 /// E.g., `"foo"`, `42`, `12.34`, or `bool`.
 // Clippy uses Hash and PartialEq
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug, Hash, PartialEq)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug, Hash, PartialEq, HashStable_Generic)]
 pub enum LitKind {
     /// A string literal (`"foo"`).
     Str(Symbol, StrStyle),
@@ -1515,12 +1609,14 @@ pub struct FnSig {
 /// signature) or provided (meaning it has a default implementation).
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct TraitItem {
+    pub attrs: Vec<Attribute>,
     pub id: NodeId,
+    pub span: Span,
+    pub vis: Visibility,
     pub ident: Ident,
-    pub attrs: Vec<Attribute>,
+
     pub generics: Generics,
     pub kind: TraitItemKind,
-    pub span: Span,
     /// See `Item::tokens` for what this is.
     pub tokens: Option<TokenStream>,
 }
@@ -1536,14 +1632,15 @@ pub enum TraitItemKind {
 /// Represents anything within an `impl` block.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct ImplItem {
+    pub attrs: Vec<Attribute>,
     pub id: NodeId,
-    pub ident: Ident,
+    pub span: Span,
     pub vis: Visibility,
+    pub ident: Ident,
+
     pub defaultness: Defaultness,
-    pub attrs: Vec<Attribute>,
     pub generics: Generics,
     pub kind: ImplItemKind,
-    pub span: Span,
     /// See `Item::tokens` for what this is.
     pub tokens: Option<TokenStream>,
 }
@@ -1554,11 +1651,11 @@ pub enum ImplItemKind {
     Const(P<Ty>, P<Expr>),
     Method(FnSig, P<Block>),
     TyAlias(P<Ty>),
-    OpaqueTy(GenericBounds),
     Macro(Mac),
 }
 
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable_Generic,
+         RustcEncodable, RustcDecodable, Debug)]
 pub enum FloatTy {
     F32,
     F64,
@@ -1587,7 +1684,8 @@ impl FloatTy {
     }
 }
 
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable_Generic,
+         RustcEncodable, RustcDecodable, Debug)]
 pub enum IntTy {
     Isize,
     I8,
@@ -1637,9 +1735,22 @@ impl IntTy {
             IntTy::I128 => 128,
         })
     }
+
+    pub fn normalize(&self, target_width: u32) -> Self {
+        match self {
+            IntTy::Isize => match target_width {
+                16 => IntTy::I16,
+                32 => IntTy::I32,
+                64 => IntTy::I64,
+                _ => unreachable!(),
+            },
+            _ => *self,
+        }
+    }
 }
 
-#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable, Copy, Debug)]
+#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable_Generic,
+         RustcEncodable, RustcDecodable, Copy, Debug)]
 pub enum UintTy {
     Usize,
     U8,
@@ -1686,6 +1797,18 @@ impl UintTy {
             UintTy::U128 => 128,
         })
     }
+
+    pub fn normalize(&self, target_width: u32) -> Self {
+        match self {
+            UintTy::Usize => match target_width {
+                16 => UintTy::U16,
+                32 => UintTy::U32,
+                64 => UintTy::U64,
+                _ => unreachable!(),
+            },
+            _ => *self,
+        }
+    }
 }
 
 /// A constraint on an associated type (e.g., `A = Bar` in `Foo<A = Bar>` or
@@ -1721,7 +1844,7 @@ pub struct Ty {
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct BareFnTy {
     pub unsafety: Unsafety,
-    pub abi: Abi,
+    pub ext: Extern,
     pub generic_params: Vec<GenericParam>,
     pub decl: P<FnDecl>,
 }
@@ -1791,6 +1914,15 @@ impl TyKind {
             false
         }
     }
+
+    /// HACK(type_alias_impl_trait, Centril): A temporary crutch used
+    /// in lowering to avoid making larger changes there and beyond.
+    pub fn opaque_top_hack(&self) -> Option<&GenericBounds> {
+        match self {
+            Self::ImplTrait(_, bounds) => Some(bounds),
+            _ => None,
+        }
+    }
 }
 
 /// Syntax used to declare a trait object.
@@ -1803,7 +1935,7 @@ pub enum TraitObjectSyntax {
 /// Inline assembly dialect.
 ///
 /// E.g., `"intel"` as in `asm!("mov eax, 2" : "={eax}"(result) : : : "intel")`.
-#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, Copy)]
+#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, Copy, HashStable_Generic)]
 pub enum AsmDialect {
     Att,
     Intel,
@@ -1961,18 +2093,40 @@ impl FnDecl {
 }
 
 /// Is the trait definition an auto trait?
-#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub enum IsAuto {
     Yes,
     No,
 }
 
-#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
+         RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub enum Unsafety {
     Unsafe,
     Normal,
 }
 
+impl Unsafety {
+    pub fn prefix_str(&self) -> &'static str {
+        match self {
+            Unsafety::Unsafe => "unsafe ",
+            Unsafety::Normal => "",
+        }
+    }
+}
+
+impl fmt::Display for Unsafety {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(
+            match *self {
+                Unsafety::Normal => "normal",
+                Unsafety::Unsafe => "unsafe",
+            },
+            f,
+        )
+    }
+}
+
 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug)]
 pub enum IsAsync {
     Async {
@@ -2003,7 +2157,7 @@ impl IsAsync {
     }
 }
 
-#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub enum Constness {
     Const,
     NotConst,
@@ -2011,25 +2165,13 @@ pub enum Constness {
 
 /// Item defaultness.
 /// For details see the [RFC #2532](https://github.com/rust-lang/rfcs/pull/2532).
-#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub enum Defaultness {
     Default,
     Final,
 }
 
-impl fmt::Display for Unsafety {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(
-            match *self {
-                Unsafety::Normal => "normal",
-                Unsafety::Unsafe => "unsafe",
-            },
-            f,
-        )
-    }
-}
-
-#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable)]
+#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable_Generic)]
 pub enum ImplPolarity {
     /// `impl Trait for Type`
     Positive,
@@ -2085,7 +2227,7 @@ pub struct Mod {
 /// E.g., `extern { .. }` or `extern C { .. }`.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct ForeignMod {
-    pub abi: Abi,
+    pub abi: Option<StrLit>,
     pub items: Vec<ForeignItem>,
 }
 
@@ -2101,22 +2243,24 @@ pub struct GlobalAsm {
 pub struct EnumDef {
     pub variants: Vec<Variant>,
 }
-
 /// Enum variant.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Variant {
-    /// Name of the variant.
-    pub ident: Ident,
     /// Attributes of the variant.
     pub attrs: Vec<Attribute>,
     /// Id of the variant (not the constructor, see `VariantData::ctor_id()`).
     pub id: NodeId,
+    /// Span
+    pub span: Span,
+    /// The visibility of the variant. Syntactically accepted but not semantically.
+    pub vis: Visibility,
+    /// Name of the variant.
+    pub ident: Ident,
+
     /// Fields and constructor id of the variant.
     pub data: VariantData,
     /// Explicit discriminant, e.g., `Foo = 1`.
     pub disr_expr: Option<AnonConst>,
-    /// Span
-    pub span: Span,
     /// Is a macro placeholder
     pub is_placeholder: bool,
 }
@@ -2163,7 +2307,7 @@ impl UseTree {
 /// Distinguishes between `Attribute`s that decorate items and Attributes that
 /// are contained as statements within items. These two cases need to be
 /// distinguished for pretty-printing.
-#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, Copy)]
+#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, Copy, HashStable_Generic)]
 pub enum AttrStyle {
     Outer,
     Inner,
@@ -2193,10 +2337,10 @@ impl rustc_serialize::Decodable for AttrId {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub struct AttrItem {
     pub path: Path,
-    pub tokens: TokenStream,
+    pub args: MacArgs,
 }
 
 /// Metadata associated with an item.
@@ -2261,7 +2405,7 @@ impl PolyTraitRef {
     }
 }
 
-#[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub enum CrateSugar {
     /// Source is `pub(crate)`.
     PubCrate,
@@ -2295,12 +2439,13 @@ impl VisibilityKind {
 /// E.g., `bar: usize` as in `struct Foo { bar: usize }`.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct StructField {
+    pub attrs: Vec<Attribute>,
+    pub id: NodeId,
     pub span: Span,
-    pub ident: Option<Ident>,
     pub vis: Visibility,
-    pub id: NodeId,
+    pub ident: Option<Ident>,
+
     pub ty: P<Ty>,
-    pub attrs: Vec<Attribute>,
     pub is_placeholder: bool,
 }
 
@@ -2343,13 +2488,14 @@ impl VariantData {
 ///
 /// The name might be a dummy name in case of anonymous items.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
-pub struct Item {
-    pub ident: Ident,
+pub struct Item<K = ItemKind> {
     pub attrs: Vec<Attribute>,
     pub id: NodeId,
-    pub kind: ItemKind,
-    pub vis: Visibility,
     pub span: Span,
+    pub vis: Visibility,
+    pub ident: Ident,
+
+    pub kind: K,
 
     /// Original tokens this item was parsed from. This isn't necessarily
     /// available for all items, although over time more and more items should
@@ -2368,24 +2514,17 @@ 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 }
-    }
+/// `extern` qualifier on a function item or function type.
+#[derive(Clone, Copy, RustcEncodable, RustcDecodable, Debug)]
+pub enum Extern {
+    None,
+    Implicit,
+    Explicit(StrLit),
 }
 
-impl Default for Abi {
-    fn default() -> Self {
-        Self::new(sym::Rust, DUMMY_SP)
+impl Extern {
+    pub fn from_abi(abi: Option<StrLit>) -> Extern {
+        abi.map_or(Extern::Implicit, Extern::Explicit)
     }
 }
 
@@ -2398,7 +2537,7 @@ pub struct FnHeader {
     pub unsafety: Unsafety,
     pub asyncness: Spanned<IsAsync>,
     pub constness: Spanned<Constness>,
-    pub abi: Abi,
+    pub ext: Extern,
 }
 
 impl Default for FnHeader {
@@ -2407,7 +2546,7 @@ impl Default for FnHeader {
             unsafety: Unsafety::Normal,
             asyncness: dummy_spanned(IsAsync::NotAsync),
             constness: dummy_spanned(Constness::NotConst),
-            abi: Abi::default(),
+            ext: Extern::None,
         }
     }
 }
@@ -2448,10 +2587,6 @@ pub enum ItemKind {
     ///
     /// E.g., `type Foo = Bar<u8>;`.
     TyAlias(P<Ty>, Generics),
-    /// An opaque `impl Trait` type alias.
-    ///
-    /// E.g., `type Foo = impl Bar + Boo;`.
-    OpaqueTy(GenericBounds, Generics),
     /// An enum definition (`enum`).
     ///
     /// E.g., `enum Foo<A, B> { C<A>, D<B> }`.
@@ -2505,7 +2640,6 @@ impl ItemKind {
             ItemKind::ForeignMod(..) => "foreign module",
             ItemKind::GlobalAsm(..) => "global asm",
             ItemKind::TyAlias(..) => "type alias",
-            ItemKind::OpaqueTy(..) => "opaque type",
             ItemKind::Enum(..) => "enum",
             ItemKind::Struct(..) => "struct",
             ItemKind::Union(..) => "union",
@@ -2516,15 +2650,7 @@ impl ItemKind {
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
-pub struct ForeignItem {
-    pub ident: Ident,
-    pub attrs: Vec<Attribute>,
-    pub kind: ForeignItemKind,
-    pub id: NodeId,
-    pub span: Span,
-    pub vis: Visibility,
-}
+pub type ForeignItem = Item<ForeignItemKind>;
 
 /// An item within an `extern` block.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
diff --git a/src/libsyntax/attr/builtin.rs b/src/libsyntax/attr/builtin.rs
index 787d69f5e99..3c10f27b60a 100644
--- a/src/libsyntax/attr/builtin.rs
+++ b/src/libsyntax/attr/builtin.rs
@@ -1,16 +1,23 @@
 //! Parsing and validation of builtin attributes
 
+use super::{mark_used, MetaItemKind};
 use crate::ast::{self, Attribute, MetaItem, NestedMetaItem};
-use crate::early_buffered_lints::BufferedEarlyLintId;
-use crate::feature_gate::{Features, GatedCfg};
+use crate::feature_gate::feature_err;
 use crate::print::pprust;
 use crate::sess::ParseSess;
 
 use errors::{Applicability, Handler};
+use std::num::NonZeroU32;
 use syntax_pos::hygiene::Transparency;
 use syntax_pos::{symbol::Symbol, symbol::sym, Span};
+use rustc_feature::{Features, find_gated_cfg, GatedCfg, is_builtin_attr_name};
+use rustc_macros::HashStable_Generic;
 
-use super::{mark_used, MetaItemKind};
+use rustc_error_codes::*;
+
+pub fn is_builtin_attr(attr: &Attribute) -> bool {
+    attr.ident().filter(|ident| is_builtin_attr_name(ident.name)).is_some()
+}
 
 enum AttrError {
     MultipleItem(String),
@@ -21,31 +28,6 @@ enum AttrError {
     UnsupportedLiteral(&'static str, /* is_bytestr */ bool),
 }
 
-/// A template that the attribute input must match.
-/// 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>,
-}
-
-impl AttributeTemplate {
-    pub fn only_word() -> Self {
-        Self { word: true, list: None, name_value_str: None }
-    }
-
-    /// Checks that the given meta-item is compatible with this template.
-    fn compatible(&self, meta_item_kind: &ast::MetaItemKind) -> bool {
-        match meta_item_kind {
-            ast::MetaItemKind::Word => self.word,
-            ast::MetaItemKind::List(..) => self.list.is_some(),
-            ast::MetaItemKind::NameValue(lit) if lit.kind.is_str() => self.name_value_str.is_some(),
-            ast::MetaItemKind::NameValue(..) => false,
-        }
-    }
-}
-
 fn handle_errors(sess: &ParseSess, span: Span, error: AttrError) {
     let diag = &sess.span_diagnostic;
     match error {
@@ -139,7 +121,8 @@ pub fn find_unwind_attr(diagnostic: Option<&Handler>, attrs: &[Attribute]) -> Op
 }
 
 /// Represents the #[stable], #[unstable], #[rustc_{deprecated,const_unstable}] attributes.
-#[derive(RustcEncodable, RustcDecodable, Copy, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(RustcEncodable, RustcDecodable, Copy, Clone, Debug,
+         PartialEq, Eq, Hash, HashStable_Generic)]
 pub struct Stability {
     pub level: StabilityLevel,
     pub feature: Symbol,
@@ -155,10 +138,11 @@ pub struct Stability {
 }
 
 /// The available stability levels.
-#[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Copy, Clone, Debug, Eq, Hash)]
+#[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd,
+         Copy, Clone, Debug, Eq, Hash, HashStable_Generic)]
 pub enum StabilityLevel {
     // Reason for the current stability level and the relevant rust-lang issue
-    Unstable { reason: Option<Symbol>, issue: u32, is_soft: bool },
+    Unstable { reason: Option<Symbol>, issue: Option<NonZeroU32>, is_soft: bool },
     Stable { since: Symbol },
 }
 
@@ -179,7 +163,8 @@ impl StabilityLevel {
     }
 }
 
-#[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Copy, Clone, Debug, Eq, Hash)]
+#[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd,
+         Copy, Clone, Debug, Eq, Hash, HashStable_Generic)]
 pub struct RustcDeprecation {
     pub since: Symbol,
     pub reason: Symbol,
@@ -395,18 +380,28 @@ fn find_stability_generic<'a, I>(sess: &ParseSess,
 
                     match (feature, reason, issue) {
                         (Some(feature), reason, Some(issue)) => {
+                            let issue = match &*issue.as_str() {
+                                // FIXME(rossmacarthur): remove "0" because "none" should be used
+                                // See #41260
+                                "none" | "0" => None,
+                                issue => {
+                                    if let Ok(num) = issue.parse() {
+                                        NonZeroU32::new(num)
+                                    } else {
+                                        span_err!(
+                                            diagnostic,
+                                            attr.span,
+                                            E0545,
+                                            "incorrect 'issue'"
+                                        );
+                                        continue
+                                    }
+                                }
+                            };
                             stab = Some(Stability {
                                 level: Unstable {
                                     reason,
-                                    issue: {
-                                        if let Ok(issue) = issue.as_str().parse() {
-                                            issue
-                                        } else {
-                                            span_err!(diagnostic, attr.span, E0545,
-                                                      "incorrect 'issue'");
-                                            continue
-                                        }
-                                    },
+                                    issue,
                                     is_soft,
                                 },
                                 feature,
@@ -539,8 +534,9 @@ pub fn find_crate_name(attrs: &[Attribute]) -> Option<Symbol> {
 /// Tests if a cfg-pattern matches the cfg set
 pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Features>) -> bool {
     eval_condition(cfg, sess, &mut |cfg| {
-        if let (Some(feats), Some(gated_cfg)) = (features, GatedCfg::gate(cfg)) {
-            gated_cfg.check_and_emit(sess, feats);
+        let gate = find_gated_cfg(|sym| cfg.check_name(sym));
+        if let (Some(feats), Some(gated_cfg)) = (features, gate) {
+            gate_cfg(&gated_cfg, cfg.span, sess, feats);
         }
         let error = |span, msg| { sess.span_diagnostic.span_err(span, msg); true };
         if cfg.path.segments.len() != 1 {
@@ -569,12 +565,21 @@ pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Feat
     })
 }
 
+fn gate_cfg(gated_cfg: &GatedCfg, cfg_span: Span, sess: &ParseSess, features: &Features) {
+    let (cfg, feature, has_feature) = gated_cfg;
+    if !has_feature(features) && !cfg_span.allows_unstable(*feature) {
+        let explain = format!("`cfg({})` is experimental and subject to change", cfg);
+        feature_err(sess, *feature, cfg_span, &explain).emit()
+    }
+}
+
 /// Evaluate a cfg-like condition (with `any` and `all`), using `eval` to
 /// evaluate individual items.
-pub fn eval_condition<F>(cfg: &ast::MetaItem, sess: &ParseSess, eval: &mut F)
-                         -> bool
-    where F: FnMut(&ast::MetaItem) -> bool
-{
+pub fn eval_condition(
+    cfg: &ast::MetaItem,
+    sess: &ParseSess,
+    eval: &mut impl FnMut(&ast::MetaItem) -> bool,
+) -> bool {
     match cfg.kind {
         ast::MetaItemKind::List(ref mis) => {
             for mi in mis.iter() {
@@ -624,7 +629,7 @@ pub fn eval_condition<F>(cfg: &ast::MetaItem, sess: &ParseSess, eval: &mut F)
     }
 }
 
-#[derive(RustcEncodable, RustcDecodable, Clone)]
+#[derive(RustcEncodable, RustcDecodable, Clone, HashStable_Generic)]
 pub struct Deprecation {
     pub since: Option<Symbol>,
     pub note: Option<Symbol>,
@@ -655,7 +660,10 @@ fn find_deprecation_generic<'a, I>(sess: &ParseSess,
             break
         }
 
-        let meta = attr.meta().unwrap();
+        let meta = match attr.meta() {
+            Some(meta) => meta,
+            None => continue,
+        };
         depr = match &meta.kind {
             MetaItemKind::Word => Some(Deprecation { since: None, note: None }),
             MetaItemKind::NameValue(..) => {
@@ -748,7 +756,7 @@ pub enum ReprAttr {
     ReprAlign(u32),
 }
 
-#[derive(Eq, PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
+#[derive(Eq, PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone, HashStable_Generic)]
 pub enum IntType {
     SignedInt(ast::IntTy),
     UnsignedInt(ast::UintTy)
@@ -938,69 +946,3 @@ pub fn find_transparency(
     let fallback = if is_legacy { Transparency::SemiTransparent } else { Transparency::Opaque };
     (transparency.map_or(fallback, |t| t.0), error)
 }
-
-pub fn check_builtin_attribute(
-    sess: &ParseSess, attr: &ast::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 attr.parse_meta(sess) {
-        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/attr/mod.rs b/src/libsyntax/attr/mod.rs
index c639431794c..079a0f6fafa 100644
--- a/src/libsyntax/attr/mod.rs
+++ b/src/libsyntax/attr/mod.rs
@@ -10,21 +10,17 @@ pub use crate::ast::Attribute;
 
 use crate::ast;
 use crate::ast::{AttrItem, AttrId, AttrKind, AttrStyle, Name, Ident, Path, PathSegment};
-use crate::ast::{MetaItem, MetaItemKind, NestedMetaItem};
+use crate::ast::{MacArgs, MacDelimiter, MetaItem, MetaItemKind, NestedMetaItem};
 use crate::ast::{Lit, LitKind, Expr, Item, Local, Stmt, StmtKind, GenericParam};
 use crate::mut_visit::visit_clobber;
 use crate::source_map::{BytePos, Spanned};
-use crate::parse;
 use crate::token::{self, Token};
 use crate::ptr::P;
-use crate::sess::ParseSess;
 use crate::symbol::{sym, Symbol};
 use crate::ThinVec;
 use crate::tokenstream::{DelimSpan, TokenStream, TokenTree, TreeAndJoint};
 use crate::GLOBALS;
 
-use errors::PResult;
-
 use log::debug;
 use syntax_pos::Span;
 
@@ -202,7 +198,7 @@ impl Attribute {
 
     pub fn is_word(&self) -> bool {
         if let AttrKind::Normal(item) = &self.kind {
-            item.tokens.is_empty()
+            matches!(item.args, MacArgs::Empty)
         } else {
             false
         }
@@ -281,18 +277,10 @@ impl MetaItem {
 }
 
 impl AttrItem {
-    crate fn meta(&self, span: Span) -> Option<MetaItem> {
-        let mut tokens = self.tokens.trees().peekable();
+    pub fn meta(&self, span: Span) -> Option<MetaItem> {
         Some(MetaItem {
             path: self.path.clone(),
-            kind: if let Some(kind) = MetaItemKind::from_tokens(&mut tokens) {
-                if tokens.peek().is_some() {
-                    return None;
-                }
-                kind
-            } else {
-                return None;
-            },
+            kind: MetaItemKind::from_mac_args(&self.args)?,
             span,
         })
     }
@@ -328,21 +316,6 @@ impl Attribute {
                 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> {
-        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))
-            }
-        }
-    }
 }
 
 /* Constructors */
@@ -381,9 +354,13 @@ crate fn mk_attr_id() -> AttrId {
     AttrId(id)
 }
 
-pub fn mk_attr(style: AttrStyle, path: Path, tokens: TokenStream, span: Span) -> Attribute {
+pub fn mk_attr(style: AttrStyle, path: Path, args: MacArgs, span: Span) -> Attribute {
+    mk_attr_from_item(style, AttrItem { path, args }, span)
+}
+
+pub fn mk_attr_from_item(style: AttrStyle, item: AttrItem, span: Span) -> Attribute {
     Attribute {
-        kind: AttrKind::Normal(AttrItem { path, tokens }),
+        kind: AttrKind::Normal(item),
         id: mk_attr_id(),
         style,
         span,
@@ -392,12 +369,12 @@ pub fn mk_attr(style: AttrStyle, path: Path, tokens: TokenStream, span: Span) ->
 
 /// Returns an inner attribute with the given value and span.
 pub fn mk_attr_inner(item: MetaItem) -> Attribute {
-    mk_attr(AttrStyle::Inner, item.path, item.kind.tokens(item.span), item.span)
+    mk_attr(AttrStyle::Inner, item.path, item.kind.mac_args(item.span), item.span)
 }
 
 /// Returns an outer attribute with the given value and span.
 pub fn mk_attr_outer(item: MetaItem) -> Attribute {
-    mk_attr(AttrStyle::Outer, item.path, item.kind.tokens(item.span), item.span)
+    mk_attr(AttrStyle::Outer, item.path, item.kind.mac_args(item.span), item.span)
 }
 
 pub fn mk_doc_comment(style: AttrStyle, comment: Symbol, span: Span) -> Attribute {
@@ -535,7 +512,26 @@ impl MetaItem {
 }
 
 impl MetaItemKind {
-    pub fn token_trees_and_joints(&self, span: Span) -> Vec<TreeAndJoint> {
+    pub fn mac_args(&self, span: Span) -> MacArgs {
+        match self {
+            MetaItemKind::Word => MacArgs::Empty,
+            MetaItemKind::NameValue(lit) => MacArgs::Eq(span, lit.token_tree().into()),
+            MetaItemKind::List(list) => {
+                let mut tts = Vec::new();
+                for (i, item) in list.iter().enumerate() {
+                    if i > 0 {
+                        tts.push(TokenTree::token(token::Comma, span).into());
+                    }
+                    tts.extend(item.token_trees_and_joints())
+                }
+                MacArgs::Delimited(
+                    DelimSpan::from_single(span), MacDelimiter::Parenthesis, TokenStream::new(tts)
+                )
+            }
+        }
+    }
+
+    fn token_trees_and_joints(&self, span: Span) -> Vec<TreeAndJoint> {
         match *self {
             MetaItemKind::Word => vec![],
             MetaItemKind::NameValue(ref lit) => {
@@ -563,33 +559,8 @@ impl MetaItemKind {
         }
     }
 
-    // Premature conversions of `TokenTree`s to `TokenStream`s can hurt
-    // performance. Do not use this function if `token_trees_and_joints()` can
-    // be used instead.
-    pub fn tokens(&self, span: Span) -> TokenStream {
-        TokenStream::new(self.token_trees_and_joints(span))
-    }
-
-    fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<MetaItemKind>
-        where I: Iterator<Item = TokenTree>,
-    {
-        let delimited = match tokens.peek().cloned() {
-            Some(TokenTree::Token(token)) if token == token::Eq => {
-                tokens.next();
-                return if let Some(TokenTree::Token(token)) = tokens.next() {
-                    Lit::from_token(&token).ok().map(MetaItemKind::NameValue)
-                } else {
-                    None
-                };
-            }
-            Some(TokenTree::Delimited(_, delim, ref tts)) if delim == token::Paren => {
-                tokens.next();
-                tts.clone()
-            }
-            _ => return Some(MetaItemKind::Word),
-        };
-
-        let mut tokens = delimited.into_trees().peekable();
+    fn list_from_tokens(tokens: TokenStream) -> Option<MetaItemKind> {
+        let mut tokens = tokens.into_trees().peekable();
         let mut result = Vec::new();
         while let Some(..) = tokens.peek() {
             let item = NestedMetaItem::from_tokens(&mut tokens)?;
@@ -601,6 +572,47 @@ impl MetaItemKind {
         }
         Some(MetaItemKind::List(result))
     }
+
+    fn name_value_from_tokens(
+        tokens: &mut impl Iterator<Item = TokenTree>,
+    ) -> Option<MetaItemKind> {
+        match tokens.next() {
+            Some(TokenTree::Token(token)) =>
+                Lit::from_token(&token).ok().map(MetaItemKind::NameValue),
+            _ => None,
+        }
+    }
+
+    fn from_mac_args(args: &MacArgs) -> Option<MetaItemKind> {
+        match args {
+            MacArgs::Delimited(_, MacDelimiter::Parenthesis, tokens) =>
+                MetaItemKind::list_from_tokens(tokens.clone()),
+            MacArgs::Delimited(..) => None,
+            MacArgs::Eq(_, tokens) => {
+                assert!(tokens.len() == 1);
+                MetaItemKind::name_value_from_tokens(&mut tokens.trees())
+            }
+            MacArgs::Empty => Some(MetaItemKind::Word),
+        }
+    }
+
+    fn from_tokens(
+        tokens: &mut iter::Peekable<impl Iterator<Item = TokenTree>>,
+    ) -> Option<MetaItemKind> {
+        match tokens.peek() {
+            Some(TokenTree::Delimited(_, token::Paren, inner_tokens)) => {
+                let inner_tokens = inner_tokens.clone();
+                tokens.next();
+                MetaItemKind::list_from_tokens(inner_tokens)
+            }
+            Some(TokenTree::Delimited(..)) => None,
+            Some(TokenTree::Token(Token { kind: token::Eq, .. })) => {
+                tokens.next();
+                MetaItemKind::name_value_from_tokens(tokens)
+            }
+            _ => Some(MetaItemKind::Word),
+        }
+    }
 }
 
 impl NestedMetaItem {
diff --git a/src/libsyntax/config.rs b/src/libsyntax/config.rs
deleted file mode 100644
index 5f89ed36e2a..00000000000
--- a/src/libsyntax/config.rs
+++ /dev/null
@@ -1,352 +0,0 @@
-use crate::attr::HasAttrs;
-use crate::feature_gate::{
-    feature_err,
-    EXPLAIN_STMT_ATTR_SYNTAX,
-    Features,
-    get_features,
-    GateIssue,
-};
-use crate::attr;
-use crate::ast;
-use crate::edition::Edition;
-use crate::mut_visit::*;
-use crate::parse;
-use crate::ptr::P;
-use crate::sess::ParseSess;
-use crate::symbol::sym;
-use crate::util::map_in_place::MapInPlace;
-
-use errors::Applicability;
-use smallvec::SmallVec;
-
-/// A folder that strips out items that do not belong in the current configuration.
-pub struct StripUnconfigured<'a> {
-    pub sess: &'a ParseSess,
-    pub features: Option<&'a Features>,
-}
-
-// `cfg_attr`-process the crate's attributes and compute the crate's features.
-pub fn features(mut krate: ast::Crate, sess: &ParseSess, edition: Edition,
-                allow_features: &Option<Vec<String>>) -> (ast::Crate, Features) {
-    let features;
-    {
-        let mut strip_unconfigured = StripUnconfigured {
-            sess,
-            features: None,
-        };
-
-        let unconfigured_attrs = krate.attrs.clone();
-        let err_count = sess.span_diagnostic.err_count();
-        if let Some(attrs) = strip_unconfigured.configure(krate.attrs) {
-            krate.attrs = attrs;
-        } else { // the entire crate is unconfigured
-            krate.attrs = Vec::new();
-            krate.module.items = Vec::new();
-            return (krate, Features::new());
-        }
-
-        features = get_features(&sess.span_diagnostic, &krate.attrs, edition, allow_features);
-
-        // Avoid reconfiguring malformed `cfg_attr`s
-        if err_count == sess.span_diagnostic.err_count() {
-            strip_unconfigured.features = Some(&features);
-            strip_unconfigured.configure(unconfigured_attrs);
-        }
-    }
-
-    (krate, features)
-}
-
-#[macro_export]
-macro_rules! configure {
-    ($this:ident, $node:ident) => {
-        match $this.configure($node) {
-            Some(node) => node,
-            None => return Default::default(),
-        }
-    }
-}
-
-impl<'a> StripUnconfigured<'a> {
-    pub fn configure<T: HasAttrs>(&mut self, mut node: T) -> Option<T> {
-        self.process_cfg_attrs(&mut node);
-        if self.in_cfg(node.attrs()) { Some(node) } else { None }
-    }
-
-    /// Parse and expand all `cfg_attr` attributes into a list of attributes
-    /// that are within each `cfg_attr` that has a true configuration predicate.
-    ///
-    /// Gives compiler warnigns if any `cfg_attr` does not contain any
-    /// attributes and is in the original source code. Gives compiler errors if
-    /// the syntax of any `cfg_attr` is incorrect.
-    pub fn process_cfg_attrs<T: HasAttrs>(&mut self, node: &mut T) {
-        node.visit_attrs(|attrs| {
-            attrs.flat_map_in_place(|attr| self.process_cfg_attr(attr));
-        });
-    }
-
-    /// Parse and expand a single `cfg_attr` attribute into a list of attributes
-    /// when the configuration predicate is true, or otherwise expand into an
-    /// empty list of attributes.
-    ///
-    /// Gives a compiler warning when the `cfg_attr` contains no attributes and
-    /// 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.has_name(sym::cfg_attr) {
-            return vec![attr];
-        }
-        if attr.get_normal_item().tokens.is_empty() {
-            self.sess.span_diagnostic
-                .struct_span_err(
-                    attr.span,
-                    "malformed `cfg_attr` attribute input",
-                ).span_suggestion(
-                    attr.span,
-                    "missing condition and attribute",
-                    "#[cfg_attr(condition, attribute, other_attribute, ...)]".to_owned(),
-                    Applicability::HasPlaceholders,
-                ).note("for more information, visit \
-                       <https://doc.rust-lang.org/reference/conditional-compilation.html\
-                       #the-cfg_attr-attribute>")
-                .emit();
-            return vec![];
-        }
-
-        let res = 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) => {
-                e.emit();
-                return vec![];
-            }
-        };
-
-        // Lint on zero attributes in source.
-        if expanded_attrs.is_empty() {
-            return vec![attr];
-        }
-
-        // At this point we know the attribute is considered used.
-        attr::mark_used(&attr);
-
-        if attr::cfg_matches(&cfg_predicate, self.sess, self.features) {
-            // We call `process_cfg_attr` recursively in case there's a
-            // `cfg_attr` inside of another `cfg_attr`. E.g.
-            //  `#[cfg_attr(false, cfg_attr(true, some_attr))]`.
-            expanded_attrs.into_iter()
-            .flat_map(|(item, span)| self.process_cfg_attr(ast::Attribute {
-                kind: ast::AttrKind::Normal(item),
-                id: attr::mk_attr_id(),
-                style: attr.style,
-                span,
-            }))
-            .collect()
-        } else {
-            vec![]
-        }
-    }
-
-    /// Determines if a node with the given attributes should be included in this configuration.
-    pub fn in_cfg(&mut self, attrs: &[ast::Attribute]) -> bool {
-        attrs.iter().all(|attr| {
-            if !is_cfg(attr) {
-                return true;
-            }
-
-            let error = |span, msg, suggestion: &str| {
-                let mut err = self.sess.span_diagnostic.struct_span_err(span, msg);
-                if !suggestion.is_empty() {
-                    err.span_suggestion(
-                        span,
-                        "expected syntax is",
-                        suggestion.into(),
-                        Applicability::MaybeIncorrect,
-                    );
-                }
-                err.emit();
-                true
-            };
-
-            let meta_item = match attr.parse_meta(self.sess) {
-                Ok(meta_item) => meta_item,
-                Err(mut err) => { err.emit(); return true; }
-            };
-            let nested_meta_items = if let Some(nested_meta_items) = meta_item.meta_item_list() {
-                nested_meta_items
-            } else {
-                return error(meta_item.span, "`cfg` is not followed by parentheses",
-                                             "cfg(/* predicate */)");
-            };
-
-            if nested_meta_items.is_empty() {
-                return error(meta_item.span, "`cfg` predicate is not specified", "");
-            } else if nested_meta_items.len() > 1 {
-                return error(nested_meta_items.last().unwrap().span(),
-                             "multiple `cfg` predicates are specified", "");
-            }
-
-            match nested_meta_items[0].meta_item() {
-                Some(meta_item) => attr::cfg_matches(meta_item, self.sess, self.features),
-                None => error(nested_meta_items[0].span(),
-                              "`cfg` predicate key cannot be a literal", ""),
-            }
-        })
-    }
-
-    /// Visit attributes on expression and statements (but not attributes on items in blocks).
-    fn visit_expr_attrs(&mut self, attrs: &[ast::Attribute]) {
-        // flag the offending attributes
-        for attr in attrs.iter() {
-            self.maybe_emit_expr_attr_err(attr);
-        }
-    }
-
-    /// If attributes are not allowed on expressions, emit an error for `attr`
-    pub fn maybe_emit_expr_attr_err(&self, attr: &ast::Attribute) {
-        if !self.features.map(|features| features.stmt_expr_attributes).unwrap_or(true) {
-            let mut err = feature_err(self.sess,
-                                      sym::stmt_expr_attributes,
-                                      attr.span,
-                                      GateIssue::Language,
-                                      EXPLAIN_STMT_ATTR_SYNTAX);
-
-            if attr.is_doc_comment() {
-                err.help("`///` is for documentation comments. For a plain comment, use `//`.");
-            }
-
-            err.emit();
-        }
-    }
-
-    pub fn configure_foreign_mod(&mut self, foreign_mod: &mut ast::ForeignMod) {
-        let ast::ForeignMod { abi: _, items } = foreign_mod;
-        items.flat_map_in_place(|item| self.configure(item));
-    }
-
-    pub fn configure_generic_params(&mut self, params: &mut Vec<ast::GenericParam>) {
-        params.flat_map_in_place(|param| self.configure(param));
-    }
-
-    fn configure_variant_data(&mut self, vdata: &mut ast::VariantData) {
-        match vdata {
-            ast::VariantData::Struct(fields, ..) | ast::VariantData::Tuple(fields, _) =>
-                fields.flat_map_in_place(|field| self.configure(field)),
-            ast::VariantData::Unit(_) => {}
-        }
-    }
-
-    pub fn configure_item_kind(&mut self, item: &mut ast::ItemKind) {
-        match item {
-            ast::ItemKind::Struct(def, _generics) |
-            ast::ItemKind::Union(def, _generics) => self.configure_variant_data(def),
-            ast::ItemKind::Enum(ast::EnumDef { variants }, _generics) => {
-                variants.flat_map_in_place(|variant| self.configure(variant));
-                for variant in variants {
-                    self.configure_variant_data(&mut variant.data);
-                }
-            }
-            _ => {}
-        }
-    }
-
-    pub fn configure_expr_kind(&mut self, expr_kind: &mut ast::ExprKind) {
-        match expr_kind {
-            ast::ExprKind::Match(_m, arms) => {
-                arms.flat_map_in_place(|arm| self.configure(arm));
-            }
-            ast::ExprKind::Struct(_path, fields, _base) => {
-                fields.flat_map_in_place(|field| self.configure(field));
-            }
-            _ => {}
-        }
-    }
-
-    pub fn configure_expr(&mut self, expr: &mut P<ast::Expr>) {
-        self.visit_expr_attrs(expr.attrs());
-
-        // If an expr is valid to cfg away it will have been removed by the
-        // outer stmt or expression folder before descending in here.
-        // Anything else is always required, and thus has to error out
-        // in case of a cfg attr.
-        //
-        // N.B., this is intentionally not part of the visit_expr() function
-        //     in order for filter_map_expr() to be able to avoid this check
-        if let Some(attr) = expr.attrs().iter().find(|a| is_cfg(a)) {
-            let msg = "removing an expression is not supported in this position";
-            self.sess.span_diagnostic.span_err(attr.span, msg);
-        }
-
-        self.process_cfg_attrs(expr)
-    }
-
-    pub fn configure_pat(&mut self, pat: &mut P<ast::Pat>) {
-        if let ast::PatKind::Struct(_path, fields, _etc) = &mut pat.kind {
-            fields.flat_map_in_place(|field| self.configure(field));
-        }
-    }
-
-    pub fn configure_fn_decl(&mut self, fn_decl: &mut ast::FnDecl) {
-        fn_decl.inputs.flat_map_in_place(|arg| self.configure(arg));
-    }
-}
-
-impl<'a> MutVisitor for StripUnconfigured<'a> {
-    fn visit_foreign_mod(&mut self, foreign_mod: &mut ast::ForeignMod) {
-        self.configure_foreign_mod(foreign_mod);
-        noop_visit_foreign_mod(foreign_mod, self);
-    }
-
-    fn visit_item_kind(&mut self, item: &mut ast::ItemKind) {
-        self.configure_item_kind(item);
-        noop_visit_item_kind(item, self);
-    }
-
-    fn visit_expr(&mut self, expr: &mut P<ast::Expr>) {
-        self.configure_expr(expr);
-        self.configure_expr_kind(&mut expr.kind);
-        noop_visit_expr(expr, self);
-    }
-
-    fn filter_map_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
-        let mut expr = configure!(self, expr);
-        self.configure_expr_kind(&mut expr.kind);
-        noop_visit_expr(&mut expr, self);
-        Some(expr)
-    }
-
-    fn flat_map_stmt(&mut self, stmt: ast::Stmt) -> SmallVec<[ast::Stmt; 1]> {
-        noop_flat_map_stmt(configure!(self, stmt), self)
-    }
-
-    fn flat_map_item(&mut self, item: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
-        noop_flat_map_item(configure!(self, item), self)
-    }
-
-    fn flat_map_impl_item(&mut self, item: ast::ImplItem) -> SmallVec<[ast::ImplItem; 1]> {
-        noop_flat_map_impl_item(configure!(self, item), self)
-    }
-
-    fn flat_map_trait_item(&mut self, item: ast::TraitItem) -> SmallVec<[ast::TraitItem; 1]> {
-        noop_flat_map_trait_item(configure!(self, item), self)
-    }
-
-    fn visit_mac(&mut self, _mac: &mut ast::Mac) {
-        // Don't configure interpolated AST (cf. issue #34171).
-        // Interpolated AST will get configured once the surrounding tokens are parsed.
-    }
-
-    fn visit_pat(&mut self, pat: &mut P<ast::Pat>) {
-        self.configure_pat(pat);
-        noop_visit_pat(pat, self)
-    }
-
-    fn visit_fn_decl(&mut self, mut fn_decl: &mut P<ast::FnDecl>) {
-        self.configure_fn_decl(&mut fn_decl);
-        noop_visit_fn_decl(fn_decl, self);
-    }
-}
-
-fn is_cfg(attr: &ast::Attribute) -> bool {
-    attr.check_name(sym::cfg)
-}
diff --git a/src/libsyntax/diagnostics/macros.rs b/src/libsyntax/diagnostics/macros.rs
index c95c5bd5d02..6679b4459a0 100644
--- a/src/libsyntax/diagnostics/macros.rs
+++ b/src/libsyntax/diagnostics/macros.rs
@@ -1,7 +1,7 @@
 #[macro_export]
 macro_rules! diagnostic_used {
     ($code:ident) => (
-        let _ = crate::error_codes::$code;
+        let _ = $code;
     )
 }
 
@@ -167,25 +167,3 @@ macro_rules! help {
         ($err).help(&format!($($message)*));
     })
 }
-
-#[macro_export]
-macro_rules! register_diagnostics {
-    ($($ecode:ident: $message:expr,)*) => (
-        $crate::register_diagnostics!{$($ecode:$message,)* ;}
-    );
-
-    ($($ecode:ident: $message:expr,)* ; $($code:ident,)*) => (
-        pub static DIAGNOSTICS: &[(&str, &str)] = &[
-            $( (stringify!($ecode), $message), )*
-        ];
-
-        $(
-            #[deny(unused)]
-            pub(crate) const $ecode: &str = $message;
-        )*
-        $(
-            #[deny(unused)]
-            pub(crate) const $code: () = ();
-        )*
-    )
-}
diff --git a/src/libsyntax/early_buffered_lints.rs b/src/libsyntax/early_buffered_lints.rs
index 5cc953b9066..2c32894a23b 100644
--- a/src/libsyntax/early_buffered_lints.rs
+++ b/src/libsyntax/early_buffered_lints.rs
@@ -3,28 +3,28 @@
 //! Since we cannot have a dependency on `librustc`, we implement some types here that are somewhat
 //! redundant. Later, these types can be converted to types for use by the rest of the compiler.
 
-use crate::ast::NodeId;
-use syntax_pos::MultiSpan;
+use rustc_session::lint::FutureIncompatibleInfo;
+use rustc_session::declare_lint;
+pub use rustc_session::lint::BufferedEarlyLint;
 
-/// Since we cannot import `LintId`s from `rustc::lint`, we define some Ids here which can later be
-/// passed to `rustc::lint::Lint::from_parser_lint_id` to get a `rustc::lint::Lint`.
-pub enum BufferedEarlyLintId {
-    IllFormedAttributeInput,
-    MetaVariableMisuse,
-    IncompleteInclude,
+declare_lint! {
+    pub ILL_FORMED_ATTRIBUTE_INPUT,
+    Deny,
+    "ill-formed attribute inputs that were previously accepted and used in practice",
+    @future_incompatible = FutureIncompatibleInfo {
+        reference: "issue #57571 <https://github.com/rust-lang/rust/issues/57571>",
+        edition: None,
+    };
 }
 
-/// Stores buffered lint info which can later be passed to `librustc`.
-pub struct BufferedEarlyLint {
-    /// The span of code that we are linting on.
-   pub span: MultiSpan,
-
-   /// The lint message.
-   pub msg: String,
-
-   /// The `NodeId` of the AST node that generated the lint.
-   pub id: NodeId,
+declare_lint! {
+    pub META_VARIABLE_MISUSE,
+    Allow,
+    "possible meta-variable misuse at macro definition"
+}
 
-   /// A lint Id that can be passed to `rustc::lint::Lint::from_parser_lint_id`.
-   pub lint_id: BufferedEarlyLintId,
+declare_lint! {
+    pub INCOMPLETE_INCLUDE,
+    Deny,
+    "trailing content in included file"
 }
diff --git a/src/libsyntax/error_codes.rs b/src/libsyntax/error_codes.rs
deleted file mode 100644
index c23c8d65a7f..00000000000
--- a/src/libsyntax/error_codes.rs
+++ /dev/null
@@ -1,544 +0,0 @@
-// 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.
-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.
-
-Erroneous code example:
-
-```compile_fail,E0536
-#[cfg(not())] // error: expected 1 cfg-pattern
-pub fn something() {}
-
-pub fn main() {}
-```
-
-The `not` predicate expects one cfg-pattern. Example:
-
-```
-#[cfg(not(target_os = "linux"))] // ok!
-pub fn something() {}
-
-pub fn main() {}
-```
-
-For more information about the cfg attribute, read:
-https://doc.rust-lang.org/reference.html#conditional-compilation
-"##,
-
-E0537: r##"
-An unknown predicate was used inside the `cfg` attribute.
-
-Erroneous code example:
-
-```compile_fail,E0537
-#[cfg(unknown())] // error: invalid predicate `unknown`
-pub fn something() {}
-
-pub fn main() {}
-```
-
-The `cfg` attribute supports only three kinds of predicates:
-
- * any
- * all
- * not
-
-Example:
-
-```
-#[cfg(not(target_os = "linux"))] // ok!
-pub fn something() {}
-
-pub fn main() {}
-```
-
-For more information about the cfg attribute, read:
-https://doc.rust-lang.org/reference.html#conditional-compilation
-"##,
-
-E0538: r##"
-Attribute contains same meta item more than once.
-
-Erroneous code example:
-
-```compile_fail,E0538
-#[deprecated(
-    since="1.0.0",
-    note="First deprecation note.",
-    note="Second deprecation note." // error: multiple same meta item
-)]
-fn deprecated_function() {}
-```
-
-Meta items are the key-value pairs inside of an attribute. Each key may only be
-used once in each attribute.
-
-To fix the problem, remove all but one of the meta items with the same key.
-
-Example:
-
-```
-#[deprecated(
-    since="1.0.0",
-    note="First deprecation note."
-)]
-fn deprecated_function() {}
-```
-"##,
-
-E0541: r##"
-An unknown meta item was used.
-
-Erroneous code example:
-
-```compile_fail,E0541
-#[deprecated(
-    since="1.0.0",
-    // error: unknown meta item
-    reason="Example invalid meta item. Should be 'note'")
-]
-fn deprecated_function() {}
-```
-
-Meta items are the key-value pairs inside of an attribute. The keys provided
-must be one of the valid keys for the specified attribute.
-
-To fix the problem, either remove the unknown meta item, or rename it if you
-provided the wrong name.
-
-In the erroneous code example above, the wrong name was provided, so changing
-to a correct one it will fix the error. Example:
-
-```
-#[deprecated(
-    since="1.0.0",
-    note="This is a valid meta item for the deprecated attribute."
-)]
-fn deprecated_function() {}
-```
-"##,
-
-E0550: r##"
-More than one `deprecated` attribute has been put on an item.
-
-Erroneous code example:
-
-```compile_fail,E0550
-#[deprecated(note = "because why not?")]
-#[deprecated(note = "right?")] // error!
-fn the_banished() {}
-```
-
-The `deprecated` attribute can only be present **once** on an item.
-
-```
-#[deprecated(note = "because why not, right?")]
-fn the_banished() {} // ok!
-```
-"##,
-
-E0551: r##"
-An invalid meta-item was used inside an attribute.
-
-Erroneous code example:
-
-```compile_fail,E0551
-#[deprecated(note)] // error!
-fn i_am_deprecated() {}
-```
-
-Meta items are the key-value pairs inside of an attribute. To fix this issue,
-you need to give a value to the `note` key. Example:
-
-```
-#[deprecated(note = "because")] // ok!
-fn i_am_deprecated() {}
-```
-"##,
-
-E0552: r##"
-A unrecognized representation attribute was used.
-
-Erroneous code example:
-
-```compile_fail,E0552
-#[repr(D)] // error: unrecognized representation hint
-struct MyStruct {
-    my_field: usize
-}
-```
-
-You can use a `repr` attribute to tell the compiler how you want a struct or
-enum to be laid out in memory.
-
-Make sure you're using one of the supported options:
-
-```
-#[repr(C)] // ok!
-struct MyStruct {
-    my_field: usize
-}
-```
-
-For more information about specifying representations, see the ["Alternative
-Representations" section] of the Rustonomicon.
-
-["Alternative Representations" section]: https://doc.rust-lang.org/nomicon/other-reprs.html
-"##,
-
-E0554: r##"
-Feature attributes are only allowed on the nightly release channel. Stable or
-beta compilers will not comply.
-
-Example of erroneous code (on a stable compiler):
-
-```ignore (depends on release channel)
-#![feature(non_ascii_idents)] // error: `#![feature]` may not be used on the
-                              //        stable release channel
-```
-
-If you need the feature, make sure to use a nightly release of the compiler
-(but be warned that the feature may be removed or altered in the future).
-"##,
-
-E0556: r##"
-The `feature` attribute was badly formed.
-
-Erroneous code example:
-
-```compile_fail,E0556
-#![feature(foo_bar_baz, foo(bar), foo = "baz", foo)] // error!
-#![feature] // error!
-#![feature = "foo"] // error!
-```
-
-The `feature` attribute only accept a "feature flag" and can only be used on
-nightly. Example:
-
-```ignore (only works in nightly)
-#![feature(flag)]
-```
-"##,
-
-E0557: r##"
-A feature attribute named a feature that has been removed.
-
-Erroneous code example:
-
-```compile_fail,E0557
-#![feature(managed_boxes)] // error: feature has been removed
-```
-
-Delete the offending feature attribute.
-"##,
-
-E0565: r##"
-A literal was used in a built-in attribute that doesn't support literals.
-
-Erroneous code example:
-
-```ignore (compile_fail not working here; see Issue #43707)
-#[inline("always")] // error: unsupported literal
-pub fn something() {}
-```
-
-Literals in attributes are new and largely unsupported in built-in attributes.
-Work to support literals where appropriate is ongoing. Try using an unquoted
-name instead:
-
-```
-#[inline(always)]
-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.
-
-```compile_fail,E0589
-#[repr(align(15))] // error: invalid `repr(align)` attribute: not a power of two
-enum Foo {
-    Bar(u64),
-}
-```
-"##,
-
-E0658: r##"
-An unstable feature was used.
-
-Erroneous code example:
-
-```compile_fail,E658
-#[repr(u128)] // error: use of unstable library feature 'repr128'
-enum Foo {
-    Bar(u64),
-}
-```
-
-If you're using a stable or a beta version of rustc, you won't be able to use
-any unstable features. In order to do so, please switch to a nightly version of
-rustc (by using rustup).
-
-If you're using a nightly version of rustc, just add the corresponding feature
-to be able to use it:
-
-```
-#![feature(repr128)]
-
-#[repr(u128)] // ok!
-enum Foo {
-    Bar(u64),
-}
-```
-"##,
-
-E0633: r##"
-The `unwind` attribute was malformed.
-
-Erroneous code example:
-
-```ignore (compile_fail not working here; see Issue #43707)
-#[unwind()] // error: expected one argument
-pub extern fn something() {}
-
-fn main() {}
-```
-
-The `#[unwind]` attribute should be used as follows:
-
-- `#[unwind(aborts)]` -- specifies that if a non-Rust ABI function
-  should abort the process if it attempts to unwind. This is the safer
-  and preferred option.
-
-- `#[unwind(allowed)]` -- specifies that a non-Rust ABI function
-  should be allowed to unwind. This can easily result in Undefined
-  Behavior (UB), so be careful.
-
-NB. The default behavior here is "allowed", but this is unspecified
-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.
-
-Erroneous code example:
-
-```ignore (limited to a warning during 2018 edition development)
-#![feature(rust_2018_preview)]
-#![feature(test_2018_feature)] // error: the feature
-                               // `test_2018_feature` is
-                               // included in the Rust 2018 edition
-```
-"##,
-
-E0725: r##"
-A feature attribute named a feature that was disallowed in the compiler
-command line flags.
-
-Erroneous code example:
-
-```ignore (can't specify compiler flags from doctests)
-#![feature(never_type)] // error: the feature `never_type` is not in
-                        // the list of allowed features
-```
-
-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
-    E0540, // multiple rustc_deprecated attributes
-    E0542, // missing 'since'
-    E0543, // missing 'reason'
-    E0544, // multiple stability levels
-    E0545, // incorrect 'issue'
-    E0546, // missing 'feature'
-    E0547, // missing 'issue'
-//  E0548, // replaced with a generic attribute input check
-    // rustc_deprecated attribute must be paired with either stable or unstable
-    // attribute
-    E0549,
-    E0553, // multiple rustc_const_unstable attributes
-//  E0555, // replaced with a generic attribute input check
-    E0629, // missing 'feature' (rustc_const_unstable)
-    // rustc_const_unstable attribute must be paired with stable/unstable
-    // attribute
-    E0630,
-    E0693, // incorrect `repr(align)` attribute format
-//  E0694, // an unknown tool name found in scoped attributes
-    E0717, // rustc_promotable without stability attribute
-}
diff --git a/src/libsyntax/expand/allocator.rs b/src/libsyntax/expand/allocator.rs
index 20487b9af03..cc3eeed04a6 100644
--- a/src/libsyntax/expand/allocator.rs
+++ b/src/libsyntax/expand/allocator.rs
@@ -5,16 +5,14 @@ use syntax_pos::Span;
 #[derive(Clone, Copy)]
 pub enum AllocatorKind {
     Global,
-    DefaultLib,
-    DefaultExe,
+    Default,
 }
 
 impl AllocatorKind {
     pub fn fn_name(&self, base: &str) -> String {
         match *self {
             AllocatorKind::Global => format!("__rg_{}", base),
-            AllocatorKind::DefaultLib => format!("__rdl_{}", base),
-            AllocatorKind::DefaultExe => format!("__rde_{}", base),
+            AllocatorKind::Default => format!("__rdl_{}", base),
         }
     }
 }
diff --git a/src/libsyntax/feature_gate/accepted.rs b/src/libsyntax/feature_gate/accepted.rs
deleted file mode 100644
index 0107611460b..00000000000
--- a/src/libsyntax/feature_gate/accepted.rs
+++ /dev/null
@@ -1,263 +0,0 @@
-//! List of the accepted feature gates.
-
-use crate::symbol::sym;
-use super::{State, Feature};
-
-macro_rules! declare_features {
-    ($(
-        $(#[doc = $doc:tt])* (accepted, $feature:ident, $ver:expr, $issue:expr, None),
-    )+) => {
-        /// Those language feature has since been Accepted (it was once Active)
-        pub const ACCEPTED_FEATURES: &[Feature] = &[
-            $(
-                Feature {
-                    state: State::Accepted,
-                    name: sym::$feature,
-                    since: $ver,
-                    issue: $issue,
-                    edition: None,
-                    description: concat!($($doc,)*),
-                }
-            ),+
-        ];
-    }
-}
-
-declare_features! (
-    // -------------------------------------------------------------------------
-    // feature-group-start: for testing purposes
-    // -------------------------------------------------------------------------
-
-    /// A temporary feature gate used to enable parser extensions needed
-    /// to bootstrap fix for #5723.
-    (accepted, issue_5723_bootstrap, "1.0.0", None, None),
-    /// These are used to test this portion of the compiler,
-    /// they don't actually mean anything.
-    (accepted, test_accepted_feature, "1.0.0", None, None),
-
-    // -------------------------------------------------------------------------
-    // feature-group-end: for testing purposes
-    // -------------------------------------------------------------------------
-
-    // -------------------------------------------------------------------------
-    // feature-group-start: accepted features
-    // -------------------------------------------------------------------------
-
-    /// Allows using associated `type`s in `trait`s.
-    (accepted, associated_types, "1.0.0", None, None),
-    /// Allows using assigning a default type to type parameters in algebraic data type definitions.
-    (accepted, default_type_params, "1.0.0", None, None),
-    // FIXME: explain `globs`.
-    (accepted, globs, "1.0.0", None, None),
-    /// Allows `macro_rules!` items.
-    (accepted, macro_rules, "1.0.0", None, None),
-    /// Allows use of `&foo[a..b]` as a slicing syntax.
-    (accepted, slicing_syntax, "1.0.0", None, None),
-    /// Allows struct variants `Foo { baz: u8, .. }` in enums (RFC 418).
-    (accepted, struct_variant, "1.0.0", None, None),
-    /// Allows indexing tuples.
-    (accepted, tuple_indexing, "1.0.0", None, None),
-    /// Allows the use of `if let` expressions.
-    (accepted, if_let, "1.0.0", None, None),
-    /// Allows the use of `while let` expressions.
-    (accepted, while_let, "1.0.0", None, None),
-    /// Allows using `#![no_std]`.
-    (accepted, no_std, "1.6.0", None, None),
-    /// Allows overloading augmented assignment operations like `a += b`.
-    (accepted, augmented_assignments, "1.8.0", Some(28235), None),
-    /// Allows empty structs and enum variants with braces.
-    (accepted, braced_empty_structs, "1.8.0", Some(29720), None),
-    /// Allows `#[deprecated]` attribute.
-    (accepted, deprecated, "1.9.0", Some(29935), None),
-    /// Allows macros to appear in the type position.
-    (accepted, type_macros, "1.13.0", Some(27245), None),
-    /// Allows use of the postfix `?` operator in expressions.
-    (accepted, question_mark, "1.13.0", Some(31436), None),
-    /// Allows `..` in tuple (struct) patterns.
-    (accepted, dotdot_in_tuple_patterns, "1.14.0", Some(33627), None),
-    /// Allows some increased flexibility in the name resolution rules,
-    /// especially around globs and shadowing (RFC 1560).
-    (accepted, item_like_imports, "1.15.0", Some(35120), None),
-    /// Allows using `Self` and associated types in struct expressions and patterns.
-    (accepted, more_struct_aliases, "1.16.0", Some(37544), None),
-    /// Allows elision of `'static` lifetimes in `static`s and `const`s.
-    (accepted, static_in_const, "1.17.0", Some(35897), None),
-    /// Allows field shorthands (`x` meaning `x: x`) in struct literal expressions.
-    (accepted, field_init_shorthand, "1.17.0", Some(37340), None),
-    /// Allows the definition recursive static items.
-    (accepted, static_recursion, "1.17.0", Some(29719), None),
-    /// Allows `pub(restricted)` visibilities (RFC 1422).
-    (accepted, pub_restricted, "1.18.0", Some(32409), None),
-    /// Allows `#![windows_subsystem]`.
-    (accepted, windows_subsystem, "1.18.0", Some(37499), None),
-    /// Allows `break {expr}` with a value inside `loop`s.
-    (accepted, loop_break_value, "1.19.0", Some(37339), None),
-    /// Allows numeric fields in struct expressions and patterns.
-    (accepted, relaxed_adts, "1.19.0", Some(35626), None),
-    /// Allows coercing non capturing closures to function pointers.
-    (accepted, closure_to_fn_coercion, "1.19.0", Some(39817), None),
-    /// Allows attributes on struct literal fields.
-    (accepted, struct_field_attributes, "1.20.0", Some(38814), None),
-    /// Allows the definition of associated constants in `trait` or `impl` blocks.
-    (accepted, associated_consts, "1.20.0", Some(29646), None),
-    /// Allows usage of the `compile_error!` macro.
-    (accepted, compile_error, "1.20.0", Some(40872), None),
-    /// Allows code like `let x: &'static u32 = &42` to work (RFC 1414).
-    (accepted, rvalue_static_promotion, "1.21.0", Some(38865), None),
-    /// Allows `Drop` types in constants (RFC 1440).
-    (accepted, drop_types_in_const, "1.22.0", Some(33156), None),
-    /// Allows the sysV64 ABI to be specified on all platforms
-    /// instead of just the platforms on which it is the C ABI.
-    (accepted, abi_sysv64, "1.24.0", Some(36167), None),
-    /// Allows `repr(align(16))` struct attribute (RFC 1358).
-    (accepted, repr_align, "1.25.0", Some(33626), None),
-    /// Allows '|' at beginning of match arms (RFC 1925).
-    (accepted, match_beginning_vert, "1.25.0", Some(44101), None),
-    /// Allows nested groups in `use` items (RFC 2128).
-    (accepted, use_nested_groups, "1.25.0", Some(44494), None),
-    /// Allows indexing into constant arrays.
-    (accepted, const_indexing, "1.26.0", Some(29947), None),
-    /// Allows using `a..=b` and `..=b` as inclusive range syntaxes.
-    (accepted, inclusive_range_syntax, "1.26.0", Some(28237), None),
-    /// Allows `..=` in patterns (RFC 1192).
-    (accepted, dotdoteq_in_patterns, "1.26.0", Some(28237), None),
-    /// Allows `fn main()` with return types which implements `Termination` (RFC 1937).
-    (accepted, termination_trait, "1.26.0", Some(43301), None),
-    /// Allows implementing `Clone` for closures where possible (RFC 2132).
-    (accepted, clone_closures, "1.26.0", Some(44490), None),
-    /// Allows implementing `Copy` for closures where possible (RFC 2132).
-    (accepted, copy_closures, "1.26.0", Some(44490), None),
-    /// Allows `impl Trait` in function arguments.
-    (accepted, universal_impl_trait, "1.26.0", Some(34511), None),
-    /// Allows `impl Trait` in function return types.
-    (accepted, conservative_impl_trait, "1.26.0", Some(34511), None),
-    /// Allows using the `u128` and `i128` types.
-    (accepted, i128_type, "1.26.0", Some(35118), None),
-    /// Allows default match binding modes (RFC 2005).
-    (accepted, match_default_bindings, "1.26.0", Some(42640), None),
-    /// Allows `'_` placeholder lifetimes.
-    (accepted, underscore_lifetimes, "1.26.0", Some(44524), None),
-    /// Allows attributes on lifetime/type formal parameters in generics (RFC 1327).
-    (accepted, generic_param_attrs, "1.27.0", Some(48848), None),
-    /// Allows `cfg(target_feature = "...")`.
-    (accepted, cfg_target_feature, "1.27.0", Some(29717), None),
-    /// Allows `#[target_feature(...)]`.
-    (accepted, target_feature, "1.27.0", None, None),
-    /// Allows using `dyn Trait` as a syntax for trait objects.
-    (accepted, dyn_trait, "1.27.0", Some(44662), None),
-    /// Allows `#[must_use]` on functions, and introduces must-use operators (RFC 1940).
-    (accepted, fn_must_use, "1.27.0", Some(43302), None),
-    /// Allows use of the `:lifetime` macro fragment specifier.
-    (accepted, macro_lifetime_matcher, "1.27.0", Some(34303), None),
-    /// Allows `#[test]` functions where the return type implements `Termination` (RFC 1937).
-    (accepted, termination_trait_test, "1.27.0", Some(48854), None),
-    /// Allows the `#[global_allocator]` attribute.
-    (accepted, global_allocator, "1.28.0", Some(27389), None),
-    /// Allows `#[repr(transparent)]` attribute on newtype structs.
-    (accepted, repr_transparent, "1.28.0", Some(43036), None),
-    /// Allows procedural macros in `proc-macro` crates.
-    (accepted, proc_macro, "1.29.0", Some(38356), None),
-    /// Allows `foo.rs` as an alternative to `foo/mod.rs`.
-    (accepted, non_modrs_mods, "1.30.0", Some(44660), None),
-    /// Allows use of the `:vis` macro fragment specifier
-    (accepted, macro_vis_matcher, "1.30.0", Some(41022), None),
-    /// Allows importing and reexporting macros with `use`,
-    /// enables macro modularization in general.
-    (accepted, use_extern_macros, "1.30.0", Some(35896), None),
-    /// Allows keywords to be escaped for use as identifiers.
-    (accepted, raw_identifiers, "1.30.0", Some(48589), None),
-    /// Allows attributes scoped to tools.
-    (accepted, tool_attributes, "1.30.0", Some(44690), None),
-    /// Allows multi-segment paths in attributes and derives.
-    (accepted, proc_macro_path_invoc, "1.30.0", Some(38356), None),
-    /// Allows all literals in attribute lists and values of key-value pairs.
-    (accepted, attr_literals, "1.30.0", Some(34981), None),
-    /// Allows inferring outlives requirements (RFC 2093).
-    (accepted, infer_outlives_requirements, "1.30.0", Some(44493), None),
-    /// Allows annotating functions conforming to `fn(&PanicInfo) -> !` with `#[panic_handler]`.
-    /// This defines the behavior of panics.
-    (accepted, panic_handler, "1.30.0", Some(44489), None),
-    /// Allows `#[used]` to preserve symbols (see llvm.used).
-    (accepted, used, "1.30.0", Some(40289), None),
-    /// Allows `crate` in paths.
-    (accepted, crate_in_paths, "1.30.0", Some(45477), None),
-    /// Allows resolving absolute paths as paths from other crates.
-    (accepted, extern_absolute_paths, "1.30.0", Some(44660), None),
-    /// Allows access to crate names passed via `--extern` through prelude.
-    (accepted, extern_prelude, "1.30.0", Some(44660), None),
-    /// Allows parentheses in patterns.
-    (accepted, pattern_parentheses, "1.31.0", Some(51087), None),
-    /// Allows the definition of `const fn` functions.
-    (accepted, min_const_fn, "1.31.0", Some(53555), None),
-    /// Allows scoped lints.
-    (accepted, tool_lints, "1.31.0", Some(44690), None),
-    /// Allows lifetime elision in `impl` headers. For example:
-    /// + `impl<I:Iterator> Iterator for &mut Iterator`
-    /// + `impl Debug for Foo<'_>`
-    (accepted, impl_header_lifetime_elision, "1.31.0", Some(15872), None),
-    /// Allows `extern crate foo as bar;`. This puts `bar` into extern prelude.
-    (accepted, extern_crate_item_prelude, "1.31.0", Some(55599), None),
-    /// Allows use of the `:literal` macro fragment specifier (RFC 1576).
-    (accepted, macro_literal_matcher, "1.32.0", Some(35625), None),
-    /// Allows use of `?` as the Kleene "at most one" operator in macros.
-    (accepted, macro_at_most_once_rep, "1.32.0", Some(48075), None),
-    /// Allows `Self` struct constructor (RFC 2302).
-    (accepted, self_struct_ctor, "1.32.0", Some(51994), None),
-    /// Allows `Self` in type definitions (RFC 2300).
-    (accepted, self_in_typedefs, "1.32.0", Some(49303), None),
-    /// Allows `use x::y;` to search `x` in the current scope.
-    (accepted, uniform_paths, "1.32.0", Some(53130), None),
-    /// Allows integer match exhaustiveness checking (RFC 2591).
-    (accepted, exhaustive_integer_patterns, "1.33.0", Some(50907), None),
-    /// Allows `use path as _;` and `extern crate c as _;`.
-    (accepted, underscore_imports, "1.33.0", Some(48216), None),
-    /// Allows `#[repr(packed(N))]` attribute on structs.
-    (accepted, repr_packed, "1.33.0", Some(33158), None),
-    /// Allows irrefutable patterns in `if let` and `while let` statements (RFC 2086).
-    (accepted, irrefutable_let_patterns, "1.33.0", Some(44495), None),
-    /// Allows calling `const unsafe fn` inside `unsafe` blocks in `const fn` functions.
-    (accepted, min_const_unsafe_fn, "1.33.0", Some(55607), None),
-    /// Allows let bindings, assignments and destructuring in `const` functions and constants.
-    /// As long as control flow is not implemented in const eval, `&&` and `||` may not be used
-    /// at the same time as let bindings.
-    (accepted, const_let, "1.33.0", Some(48821), None),
-    /// Allows `#[cfg_attr(predicate, multiple, attributes, here)]`.
-    (accepted, cfg_attr_multi, "1.33.0", Some(54881), None),
-    /// Allows top level or-patterns (`p | q`) in `if let` and `while let`.
-    (accepted, if_while_or_patterns, "1.33.0", Some(48215), None),
-    /// Allows `cfg(target_vendor = "...")`.
-    (accepted, cfg_target_vendor, "1.33.0", Some(29718), None),
-    /// Allows `extern crate self as foo;`.
-    /// This puts local crate root into extern prelude under name `foo`.
-    (accepted, extern_crate_self, "1.34.0", Some(56409), None),
-    /// Allows arbitrary delimited token streams in non-macro attributes.
-    (accepted, unrestricted_attribute_tokens, "1.34.0", Some(55208), None),
-    /// Allows paths to enum variants on type aliases including `Self`.
-    (accepted, type_alias_enum_variants, "1.37.0", Some(49683), None),
-    /// Allows using `#[repr(align(X))]` on enums with equivalent semantics
-    /// to wrapping an enum in a wrapper struct with `#[repr(align(X))]`.
-    (accepted, repr_align_enum, "1.37.0", Some(57996), None),
-    /// Allows `const _: TYPE = VALUE`.
-    (accepted, underscore_const_names, "1.37.0", Some(54912), None),
-    /// Allows free and inherent `async fn`s, `async` blocks, and `<expr>.await` expressions.
-    (accepted, async_await, "1.39.0", Some(50547), None),
-    /// Allows mixing bind-by-move in patterns and references to those identifiers in guards.
-    (accepted, bind_by_move_pattern_guards, "1.39.0", Some(15287), None),
-    /// Allows attributes in formal function parameters.
-    (accepted, param_attrs, "1.39.0", Some(60406), None),
-    /// Allows macro invocations in `extern {}` blocks.
-    (accepted, macros_in_extern, "1.40.0", Some(49476), None),
-    /// Allows future-proofing enums/structs with the `#[non_exhaustive]` attribute (RFC 2008).
-    (accepted, non_exhaustive, "1.40.0", Some(44109), None),
-    /// Allows calling constructor functions in `const fn`.
-    (accepted, const_constructor, "1.40.0", Some(61456), None),
-    /// Allows the use of `#[cfg(doctest)]`, set when rustdoc is collecting doctests.
-    (accepted, cfg_doctest, "1.40.0", Some(62210), None),
-    /// Allows relaxing the coherence rules such that
-    /// `impl<T> ForeignTrait<LocalType> for ForeignType<T>` is permitted.
-    (accepted, re_rebalance_coherence, "1.41.0", Some(55437), None),
-
-    // -------------------------------------------------------------------------
-    // feature-group-end: accepted features
-    // -------------------------------------------------------------------------
-);
diff --git a/src/libsyntax/feature_gate/active.rs b/src/libsyntax/feature_gate/active.rs
deleted file mode 100644
index 1d198fca56b..00000000000
--- a/src/libsyntax/feature_gate/active.rs
+++ /dev/null
@@ -1,545 +0,0 @@
-//! List of the active feature gates.
-
-use super::{State, Feature};
-
-use crate::edition::Edition;
-use crate::symbol::{Symbol, sym};
-
-use syntax_pos::Span;
-
-macro_rules! set {
-    ($field: ident) => {{
-        fn f(features: &mut Features, _: Span) {
-            features.$field = true;
-        }
-        f as fn(&mut Features, Span)
-    }}
-}
-
-macro_rules! declare_features {
-    ($(
-        $(#[doc = $doc:tt])* (active, $feature:ident, $ver:expr, $issue:expr, $edition:expr),
-    )+) => {
-        /// Represents active features that are currently being implemented or
-        /// currently being considered for addition/removal.
-        pub const ACTIVE_FEATURES:
-            &[Feature] =
-            &[$(
-                // (sym::$feature, $ver, $issue, $edition, set!($feature))
-                Feature {
-                    state: State::Active { set: set!($feature) },
-                    name: sym::$feature,
-                    since: $ver,
-                    issue: $issue,
-                    edition: $edition,
-                    description: concat!($($doc,)*),
-                }
-            ),+];
-
-        /// A set of features to be used by later passes.
-        #[derive(Clone)]
-        pub struct Features {
-            /// `#![feature]` attrs for language features, for error reporting.
-            pub declared_lang_features: Vec<(Symbol, Span, Option<Symbol>)>,
-            /// `#![feature]` attrs for non-language (library) features.
-            pub declared_lib_features: Vec<(Symbol, Span)>,
-            $(
-                $(#[doc = $doc])*
-                pub $feature: bool
-            ),+
-        }
-
-        impl Features {
-            pub fn new() -> Features {
-                Features {
-                    declared_lang_features: Vec::new(),
-                    declared_lib_features: Vec::new(),
-                    $($feature: false),+
-                }
-            }
-
-            pub fn walk_feature_fields<F>(&self, mut f: F)
-                where F: FnMut(&str, bool)
-            {
-                $(f(stringify!($feature), self.$feature);)+
-            }
-        }
-    };
-}
-
-impl Feature {
-    /// Sets this feature in `Features`. Panics if called on a non-active feature.
-    pub fn set(&self, features: &mut Features, span: Span) {
-        match self.state {
-            State::Active { set } => set(features, span),
-            _ => panic!("called `set` on feature `{}` which is not `active`", self.name)
-        }
-    }
-}
-
-// If you change this, please modify `src/doc/unstable-book` as well.
-//
-// Don't ever remove anything from this list; move them to `removed.rs`.
-//
-// The version numbers here correspond to the version in which the current status
-// was set. This is most important for knowing when a particular feature became
-// stable (active).
-//
-// Note that the features are grouped into internal/user-facing and then
-// sorted by version inside those groups. This is enforced with tidy.
-//
-// N.B., `tools/tidy/src/features.rs` parses this information directly out of the
-// source, so take care when modifying it.
-
-declare_features! (
-    // -------------------------------------------------------------------------
-    // feature-group-start: internal feature gates
-    // -------------------------------------------------------------------------
-
-    // no-tracking-issue-start
-
-    /// Allows using compiler's own crates.
-    (active, rustc_private, "1.0.0", Some(27812), None),
-
-    /// Allows using the `rust-intrinsic`'s "ABI".
-    (active, intrinsics, "1.0.0", None, None),
-
-    /// Allows using `#[lang = ".."]` attribute for linking items to special compiler logic.
-    (active, lang_items, "1.0.0", None, None),
-
-    /// Allows using the `#[stable]` and `#[unstable]` attributes.
-    (active, staged_api, "1.0.0", None, None),
-
-    /// Allows using `#[allow_internal_unstable]`. This is an
-    /// attribute on `macro_rules!` and can't use the attribute handling
-    /// below (it has to be checked before expansion possibly makes
-    /// macros disappear).
-    (active, allow_internal_unstable, "1.0.0", None, None),
-
-    /// Allows using `#[allow_internal_unsafe]`. This is an
-    /// attribute on `macro_rules!` and can't use the attribute handling
-    /// below (it has to be checked before expansion possibly makes
-    /// macros disappear).
-    (active, allow_internal_unsafe, "1.0.0", None, None),
-
-    /// Allows using `#[rustc_const_unstable(feature = "foo", ..)]` which
-    /// lets a function to be `const` when opted into with `#![feature(foo)]`.
-    (active, rustc_const_unstable, "1.0.0", None, None),
-
-    /// no-tracking-issue-end
-
-    /// Allows using `#[link_name="llvm.*"]`.
-    (active, link_llvm_intrinsics, "1.0.0", Some(29602), None),
-
-    /// Allows using `rustc_*` attributes (RFC 572).
-    (active, rustc_attrs, "1.0.0", Some(29642), None),
-
-    /// Allows using the `box $expr` syntax.
-    (active, box_syntax, "1.0.0", Some(49733), None),
-
-    /// Allows using `#[main]` to replace the entrypoint `#[lang = "start"]` calls.
-    (active, main, "1.0.0", Some(29634), None),
-
-    /// Allows using `#[start]` on a function indicating that it is the program entrypoint.
-    (active, start, "1.0.0", Some(29633), None),
-
-    /// Allows using the `#[fundamental]` attribute.
-    (active, fundamental, "1.0.0", Some(29635), None),
-
-    /// Allows using the `rust-call` ABI.
-    (active, unboxed_closures, "1.0.0", Some(29625), None),
-
-    /// Allows using the `#[linkage = ".."]` attribute.
-    (active, linkage, "1.0.0", Some(29603), None),
-
-    /// Allows features specific to OIBIT (auto traits).
-    (active, optin_builtin_traits, "1.0.0", Some(13231), None),
-
-    /// Allows using `box` in patterns (RFC 469).
-    (active, box_patterns, "1.0.0", Some(29641), None),
-
-    // no-tracking-issue-start
-
-    /// Allows using `#[prelude_import]` on glob `use` items.
-    (active, prelude_import, "1.2.0", None, None),
-
-    // no-tracking-issue-end
-
-    // no-tracking-issue-start
-
-    /// Allows using `#[omit_gdb_pretty_printer_section]`.
-    (active, omit_gdb_pretty_printer_section, "1.5.0", None, None),
-
-    /// Allows using the `vectorcall` ABI.
-    (active, abi_vectorcall, "1.7.0", None, None),
-
-    // no-tracking-issue-end
-
-    /// Allows using `#[structural_match]` which indicates that a type is structurally matchable.
-    (active, structural_match, "1.8.0", Some(31434), None),
-
-    /// Allows using the `may_dangle` attribute (RFC 1327).
-    (active, dropck_eyepatch, "1.10.0", Some(34761), None),
-
-    /// Allows using the `#![panic_runtime]` attribute.
-    (active, panic_runtime, "1.10.0", Some(32837), None),
-
-    /// Allows declaring with `#![needs_panic_runtime]` that a panic runtime is needed.
-    (active, needs_panic_runtime, "1.10.0", Some(32837), None),
-
-    // no-tracking-issue-start
-
-    /// Allows identifying the `compiler_builtins` crate.
-    (active, compiler_builtins, "1.13.0", None, None),
-
-    /// Allows using the `unadjusted` ABI; perma-unstable.
-    (active, abi_unadjusted, "1.16.0", None, None),
-
-    /// Allows identifying crates that contain sanitizer runtimes.
-    (active, sanitizer_runtime, "1.17.0", None, None),
-
-    /// Used to identify crates that contain the profiler runtime.
-    (active, profiler_runtime, "1.18.0", None, None),
-
-    /// Allows using the `thiscall` ABI.
-    (active, abi_thiscall, "1.19.0", None, None),
-
-    /// Allows using `#![needs_allocator]`, an implementation detail of `#[global_allocator]`.
-    (active, allocator_internals, "1.20.0", None, None),
-
-    // no-tracking-issue-end
-
-    /// Added for testing E0705; perma-unstable.
-    (active, test_2018_feature, "1.31.0", Some(0), Some(Edition::Edition2018)),
-
-    // -------------------------------------------------------------------------
-    // feature-group-end: internal feature gates
-    // -------------------------------------------------------------------------
-
-    // -------------------------------------------------------------------------
-    // feature-group-start: actual feature gates (target features)
-    // -------------------------------------------------------------------------
-
-    // FIXME: Document these and merge with the list below.
-
-    // Unstable `#[target_feature]` directives.
-    (active, arm_target_feature, "1.27.0", Some(44839), None),
-    (active, aarch64_target_feature, "1.27.0", Some(44839), None),
-    (active, hexagon_target_feature, "1.27.0", Some(44839), None),
-    (active, powerpc_target_feature, "1.27.0", Some(44839), None),
-    (active, mips_target_feature, "1.27.0", Some(44839), None),
-    (active, avx512_target_feature, "1.27.0", Some(44839), None),
-    (active, mmx_target_feature, "1.27.0", Some(44839), None),
-    (active, sse4a_target_feature, "1.27.0", Some(44839), None),
-    (active, tbm_target_feature, "1.27.0", Some(44839), None),
-    (active, wasm_target_feature, "1.30.0", Some(44839), None),
-    (active, adx_target_feature, "1.32.0", Some(44839), None),
-    (active, cmpxchg16b_target_feature, "1.32.0", Some(44839), None),
-    (active, movbe_target_feature, "1.34.0", Some(44839), None),
-    (active, rtm_target_feature, "1.35.0", Some(44839), None),
-    (active, f16c_target_feature, "1.36.0", Some(44839), None),
-
-    // -------------------------------------------------------------------------
-    // feature-group-end: actual feature gates (target features)
-    // -------------------------------------------------------------------------
-
-    // -------------------------------------------------------------------------
-    // feature-group-start: actual feature gates
-    // -------------------------------------------------------------------------
-
-    /// Allows using the `#[link_args]` attribute.
-    (active, link_args, "1.0.0", Some(29596), None),
-
-    /// Allows defining identifiers beyond ASCII.
-    (active, non_ascii_idents, "1.0.0", Some(55467), None),
-
-    /// Allows using `#[plugin_registrar]` on functions.
-    (active, plugin_registrar, "1.0.0", Some(29597), None),
-
-    /// Allows using `#![plugin(myplugin)]`.
-    (active, plugin, "1.0.0", Some(29597), None),
-
-    /// Allows using `#[thread_local]` on `static` items.
-    (active, thread_local, "1.0.0", Some(29594), None),
-
-    /// Allows the use of SIMD types in functions declared in `extern` blocks.
-    (active, simd_ffi, "1.0.0", Some(27731), None),
-
-    /// Allows using custom attributes (RFC 572).
-    (active, custom_attribute, "1.0.0", Some(29642), None),
-
-    /// Allows using non lexical lifetimes (RFC 2094).
-    (active, nll, "1.0.0", Some(43234), None),
-
-    /// Allows using slice patterns.
-    (active, slice_patterns, "1.0.0", Some(62254), None),
-
-    /// Allows the definition of `const` functions with some advanced features.
-    (active, const_fn, "1.2.0", Some(57563), None),
-
-    /// Allows associated type defaults.
-    (active, associated_type_defaults, "1.2.0", Some(29661), None),
-
-    /// Allows `#![no_core]`.
-    (active, no_core, "1.3.0", Some(29639), None),
-
-    /// Allows default type parameters to influence type inference.
-    (active, default_type_parameter_fallback, "1.3.0", Some(27336), None),
-
-    /// Allows `repr(simd)` and importing the various simd intrinsics.
-    (active, repr_simd, "1.4.0", Some(27731), None),
-
-    /// Allows `extern "platform-intrinsic" { ... }`.
-    (active, platform_intrinsics, "1.4.0", Some(27731), None),
-
-    /// Allows `#[unwind(..)]`.
-    ///
-    /// Permits specifying whether a function should permit unwinding or abort on unwind.
-    (active, unwind_attributes, "1.4.0", Some(58760), None),
-
-    /// Allows `#[no_debug]`.
-    (active, no_debug, "1.5.0", Some(29721), None),
-
-    /// Allows attributes on expressions and non-item statements.
-    (active, stmt_expr_attributes, "1.6.0", Some(15701), None),
-
-    /// Allows the use of type ascription in expressions.
-    (active, type_ascription, "1.6.0", Some(23416), None),
-
-    /// Allows `cfg(target_thread_local)`.
-    (active, cfg_target_thread_local, "1.7.0", Some(29594), None),
-
-    /// Allows specialization of implementations (RFC 1210).
-    (active, specialization, "1.7.0", Some(31844), None),
-
-    /// Allows using `#[naked]` on functions.
-    (active, naked_functions, "1.9.0", Some(32408), None),
-
-    /// Allows `cfg(target_has_atomic = "...")`.
-    (active, cfg_target_has_atomic, "1.9.0", Some(32976), None),
-
-    /// Allows `X..Y` patterns.
-    (active, exclusive_range_pattern, "1.11.0", Some(37854), None),
-
-    /// Allows the `!` type. Does not imply 'exhaustive_patterns' (below) any more.
-    (active, never_type, "1.13.0", Some(35121), None),
-
-    /// Allows exhaustive pattern matching on types that contain uninhabited types.
-    (active, exhaustive_patterns, "1.13.0", Some(51085), None),
-
-    /// Allows `union`s to implement `Drop`. Moreover, `union`s may now include fields
-    /// that don't implement `Copy` as long as they don't have any drop glue.
-    /// This is checked recursively. On encountering type variable where no progress can be made,
-    /// `T: Copy` is used as a substitute for "no drop glue".
-    ///
-    /// NOTE: A limited form of `union U { ... }` was accepted in 1.19.0.
-    (active, untagged_unions, "1.13.0", Some(55149), None),
-
-    /// Allows `#[link(..., cfg(..))]`.
-    (active, link_cfg, "1.14.0", Some(37406), None),
-
-    /// Allows `extern "ptx-*" fn()`.
-    (active, abi_ptx, "1.15.0", Some(38788), None),
-
-    /// Allows the `#[repr(i128)]` attribute for enums.
-    (active, repr128, "1.16.0", Some(35118), None),
-
-    /// Allows `#[link(kind="static-nobundle"...)]`.
-    (active, static_nobundle, "1.16.0", Some(37403), None),
-
-    /// Allows `extern "msp430-interrupt" fn()`.
-    (active, abi_msp430_interrupt, "1.16.0", Some(38487), None),
-
-    /// Allows declarative macros 2.0 (`macro`).
-    (active, decl_macro, "1.17.0", Some(39412), None),
-
-    /// Allows `extern "x86-interrupt" fn()`.
-    (active, abi_x86_interrupt, "1.17.0", Some(40180), None),
-
-    /// Allows overlapping impls of marker traits.
-    (active, overlapping_marker_traits, "1.18.0", Some(29864), None),
-
-    /// Allows a test to fail without failing the whole suite.
-    (active, allow_fail, "1.19.0", Some(46488), None),
-
-    /// Allows unsized tuple coercion.
-    (active, unsized_tuple_coercion, "1.20.0", Some(42877), None),
-
-    /// Allows defining generators.
-    (active, generators, "1.21.0", Some(43122), None),
-
-    /// Allows `#[doc(cfg(...))]`.
-    (active, doc_cfg, "1.21.0", Some(43781), None),
-
-    /// Allows `#[doc(masked)]`.
-    (active, doc_masked, "1.21.0", Some(44027), None),
-
-    /// Allows `#[doc(spotlight)]`.
-    (active, doc_spotlight, "1.22.0", Some(45040), None),
-
-    /// Allows `#[doc(include = "some-file")]`.
-    (active, external_doc, "1.22.0", Some(44732), None),
-
-    /// Allows using `crate` as visibility modifier, synonymous with `pub(crate)`.
-    (active, crate_visibility_modifier, "1.23.0", Some(53120), None),
-
-    /// Allows defining `extern type`s.
-    (active, extern_types, "1.23.0", Some(43467), None),
-
-    /// Allows trait methods with arbitrary self types.
-    (active, arbitrary_self_types, "1.23.0", Some(44874), None),
-
-    /// Allows in-band quantification of lifetime bindings (e.g., `fn foo(x: &'a u8) -> &'a u8`).
-    (active, in_band_lifetimes, "1.23.0", Some(44524), None),
-
-    /// Allows associated types to be generic, e.g., `type Foo<T>;` (RFC 1598).
-    (active, generic_associated_types, "1.23.0", Some(44265), None),
-
-    /// Allows defining `trait X = A + B;` alias items.
-    (active, trait_alias, "1.24.0", Some(41517), None),
-
-    /// Allows infering `'static` outlives requirements (RFC 2093).
-    (active, infer_static_outlives_requirements, "1.26.0", Some(54185), None),
-
-    /// Allows accessing fields of unions inside `const` functions.
-    (active, const_fn_union, "1.27.0", Some(51909), None),
-
-    /// Allows casting raw pointers to `usize` during const eval.
-    (active, const_raw_ptr_to_usize_cast, "1.27.0", Some(51910), None),
-
-    /// Allows dereferencing raw pointers during const eval.
-    (active, const_raw_ptr_deref, "1.27.0", Some(51911), None),
-
-    /// Allows comparing raw pointers during const eval.
-    (active, const_compare_raw_pointers, "1.27.0", Some(53020), None),
-
-    /// Allows `#[doc(alias = "...")]`.
-    (active, doc_alias, "1.27.0", Some(50146), None),
-
-    /// Allows inconsistent bounds in where clauses.
-    (active, trivial_bounds, "1.28.0", Some(48214), None),
-
-    /// Allows `'a: { break 'a; }`.
-    (active, label_break_value, "1.28.0", Some(48594), None),
-
-    /// Allows using `#[doc(keyword = "...")]`.
-    (active, doc_keyword, "1.28.0", Some(51315), None),
-
-    /// Allows reinterpretation of the bits of a value of one type as another
-    /// type during const eval.
-    (active, const_transmute, "1.29.0", Some(53605), None),
-
-    /// Allows using `try {...}` expressions.
-    (active, try_blocks, "1.29.0", Some(31436), None),
-
-    /// Allows defining an `#[alloc_error_handler]`.
-    (active, alloc_error_handler, "1.29.0", Some(51540), None),
-
-    /// Allows using the `amdgpu-kernel` ABI.
-    (active, abi_amdgpu_kernel, "1.29.0", Some(51575), None),
-
-    /// Allows panicking during const eval (producing compile-time errors).
-    (active, const_panic, "1.30.0", Some(51999), None),
-
-    /// Allows `#[marker]` on certain traits allowing overlapping implementations.
-    (active, marker_trait_attr, "1.30.0", Some(29864), None),
-
-    /// Allows macro invocations on modules expressions and statements and
-    /// procedural macros to expand to non-items.
-    (active, proc_macro_hygiene, "1.30.0", Some(54727), None),
-
-    /// Allows unsized rvalues at arguments and parameters.
-    (active, unsized_locals, "1.30.0", Some(48055), None),
-
-    /// Allows custom test frameworks with `#![test_runner]` and `#[test_case]`.
-    (active, custom_test_frameworks, "1.30.0", Some(50297), None),
-
-    /// Allows non-builtin attributes in inner attribute position.
-    (active, custom_inner_attributes, "1.30.0", Some(54726), None),
-
-    /// Allows `impl Trait` in bindings (`let`, `const`, `static`).
-    (active, impl_trait_in_bindings, "1.30.0", Some(63065), None),
-
-    /// Allows using `reason` in lint attributes and the `#[expect(lint)]` lint check.
-    (active, lint_reasons, "1.31.0", Some(54503), None),
-
-    /// Allows exhaustive integer pattern matching on `usize` and `isize`.
-    (active, precise_pointer_size_matching, "1.32.0", Some(56354), None),
-
-    /// Allows using `#[ffi_returns_twice]` on foreign functions.
-    (active, ffi_returns_twice, "1.34.0", Some(58314), None),
-
-    /// Allows const generic types (e.g. `struct Foo<const N: usize>(...);`).
-    (active, const_generics, "1.34.0", Some(44580), None),
-
-    /// Allows using `#[optimize(X)]`.
-    (active, optimize_attribute, "1.34.0", Some(54882), None),
-
-    /// Allows using C-variadics.
-    (active, c_variadic, "1.34.0", Some(44930), None),
-
-    /// Allows the user of associated type bounds.
-    (active, associated_type_bounds, "1.34.0", Some(52662), None),
-
-    /// Allows `if/while p && let q = r && ...` chains.
-    (active, let_chains, "1.37.0", Some(53667), None),
-
-    /// Allows #[repr(transparent)] on enums (RFC 2645).
-    (active, transparent_enums, "1.37.0", Some(60405), None),
-
-    /// Allows #[repr(transparent)] on unions (RFC 2645).
-    (active, transparent_unions, "1.37.0", Some(60405), None),
-
-    /// Allows explicit discriminants on non-unit enum variants.
-    (active, arbitrary_enum_discriminant, "1.37.0", Some(60553), None),
-
-    /// Allows `impl Trait` with multiple unrelated lifetimes.
-    (active, member_constraints, "1.37.0", Some(61977), None),
-
-    /// Allows `async || body` closures.
-    (active, async_closure, "1.37.0", Some(62290), None),
-
-    /// Allows `[x; N]` where `x` is a constant (RFC 2203).
-    (active, const_in_array_repeat_expressions, "1.37.0", Some(49147), None),
-
-    /// Allows `impl Trait` to be used inside type aliases (RFC 2515).
-    (active, type_alias_impl_trait, "1.38.0", Some(63063), None),
-
-    /// Allows the use of or-patterns (e.g., `0 | 1`).
-    (active, or_patterns, "1.38.0", Some(54883), None),
-
-    /// Allows the definition of `const extern fn` and `const unsafe extern fn`.
-    (active, const_extern_fn, "1.40.0", Some(64926), None),
-
-    /// Allows the use of raw-dylibs (RFC 2627).
-    (active, raw_dylib, "1.40.0", Some(58713), None),
-
-    /// Allows `#[track_caller]` to be used which provides
-    /// accurate caller location reporting during panic (RFC 2091).
-    (active, track_caller, "1.40.0", Some(47809), None),
-
-    /// Allows making `dyn Trait` well-formed even if `Trait` is not object safe.
-    /// In that case, `dyn Trait: Trait` does not hold. Moreover, coercions and
-    /// casts in safe Rust to `dyn Trait` for such a `Trait` is also forbidden.
-    (active, object_safe_for_dispatch, "1.40.0", Some(43561), None),
-
-    /// Allows using the `efiapi` ABI.
-    (active, abi_efiapi, "1.40.0", Some(65815), None),
-
-    // -------------------------------------------------------------------------
-    // feature-group-end: actual feature gates
-    // -------------------------------------------------------------------------
-);
-
-/// Some features are known to be incomplete and using them is likely to have
-/// unanticipated results, such as compiler crashes. We warn the user about these
-/// to alert them.
-pub const INCOMPLETE_FEATURES: &[Symbol] = &[
-    sym::impl_trait_in_bindings,
-    sym::generic_associated_types,
-    sym::const_generics,
-    sym::or_patterns,
-    sym::let_chains,
-    sym::raw_dylib,
-    sym::track_caller,
-];
diff --git a/src/libsyntax/feature_gate/builtin_attrs.rs b/src/libsyntax/feature_gate/builtin_attrs.rs
deleted file mode 100644
index b32a887c6b2..00000000000
--- a/src/libsyntax/feature_gate/builtin_attrs.rs
+++ /dev/null
@@ -1,598 +0,0 @@
-//! Built-in attributes and `cfg` flag gating.
-
-use AttributeType::*;
-use AttributeGate::*;
-
-use super::check::{emit_feature_err, GateIssue};
-use super::check::{Stability, EXPLAIN_ALLOW_INTERNAL_UNSAFE, EXPLAIN_ALLOW_INTERNAL_UNSTABLE};
-use super::active::Features;
-
-use crate::ast;
-use crate::attr::AttributeTemplate;
-use crate::sess::ParseSess;
-use crate::symbol::{Symbol, sym};
-
-use syntax_pos::Span;
-use rustc_data_structures::fx::FxHashMap;
-use lazy_static::lazy_static;
-
-type GateFn = fn(&Features) -> bool;
-
-macro_rules! cfg_fn {
-    ($field: ident) => {
-        (|features| { features.$field }) as GateFn
-    }
-}
-
-/// `cfg(...)`'s that are feature gated.
-const GATED_CFGS: &[(Symbol, Symbol, GateFn)] = &[
-    // (name in cfg, feature, function to check if the feature is enabled)
-    (sym::target_thread_local, sym::cfg_target_thread_local, cfg_fn!(cfg_target_thread_local)),
-    (sym::target_has_atomic, sym::cfg_target_has_atomic, cfg_fn!(cfg_target_has_atomic)),
-    (sym::target_has_atomic_load_store, sym::cfg_target_has_atomic, cfg_fn!(cfg_target_has_atomic)),
-    (sym::rustdoc, sym::doc_cfg, cfg_fn!(doc_cfg)),
-];
-
-#[derive(Debug)]
-pub struct GatedCfg {
-    span: Span,
-    index: usize,
-}
-
-impl GatedCfg {
-    pub fn gate(cfg: &ast::MetaItem) -> Option<GatedCfg> {
-        GATED_CFGS.iter()
-                  .position(|info| cfg.check_name(info.0))
-                  .map(|idx| {
-                      GatedCfg {
-                          span: cfg.span,
-                          index: idx
-                      }
-                  })
-    }
-
-    pub fn check_and_emit(&self, sess: &ParseSess, features: &Features) {
-        let (cfg, feature, has_feature) = GATED_CFGS[self.index];
-        if !has_feature(features) && !self.span.allows_unstable(feature) {
-            let explain = format!("`cfg({})` is experimental and subject to change", cfg);
-            emit_feature_err(sess, feature, self.span, GateIssue::Language, &explain);
-        }
-    }
-}
-
-// If you change this, please modify `src/doc/unstable-book` as well. You must
-// move that documentation into the relevant place in the other docs, and
-// remove the chapter on the flag.
-
-#[derive(Copy, Clone, PartialEq, Debug)]
-pub enum AttributeType {
-    /// Normal, builtin attribute that is consumed
-    /// by the compiler before the unused_attribute check
-    Normal,
-
-    /// Builtin attribute that may not be consumed by the compiler
-    /// before the unused_attribute check. These attributes
-    /// will be ignored by the unused_attribute lint
-    Whitelisted,
-
-    /// Builtin attribute that is only allowed at the crate level
-    CrateLevel,
-}
-
-#[derive(Clone, Copy)]
-pub enum AttributeGate {
-    /// Is gated by a given feature gate, reason
-    /// and function to check if enabled
-    Gated(Stability, Symbol, &'static str, fn(&Features) -> bool),
-
-    /// Ungated attribute, can be used on all release channels
-    Ungated,
-}
-
-// fn() is not Debug
-impl std::fmt::Debug for AttributeGate {
-    fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match *self {
-            Self::Gated(ref stab, name, expl, _) =>
-                write!(fmt, "Gated({:?}, {}, {})", stab, name, expl),
-            Self::Ungated => write!(fmt, "Ungated")
-        }
-    }
-}
-
-impl AttributeGate {
-    fn is_deprecated(&self) -> bool {
-        match *self {
-            Self::Gated(Stability::Deprecated(_, _), ..) => true,
-            _ => false,
-        }
-    }
-}
-
-/// A convenience macro for constructing attribute templates.
-/// E.g., `template!(Word, List: "description")` means that the attribute
-/// supports forms `#[attr]` and `#[attr(description)]`.
-macro_rules! template {
-    (Word) => { template!(@ true, None, None) };
-    (List: $descr: expr) => { template!(@ false, Some($descr), None) };
-    (NameValueStr: $descr: expr) => { template!(@ false, None, Some($descr)) };
-    (Word, List: $descr: expr) => { template!(@ true, Some($descr), None) };
-    (Word, NameValueStr: $descr: expr) => { template!(@ true, None, Some($descr)) };
-    (List: $descr1: expr, NameValueStr: $descr2: expr) => {
-        template!(@ false, Some($descr1), Some($descr2))
-    };
-    (Word, List: $descr1: expr, NameValueStr: $descr2: expr) => {
-        template!(@ true, Some($descr1), Some($descr2))
-    };
-    (@ $word: expr, $list: expr, $name_value_str: expr) => { AttributeTemplate {
-        word: $word, list: $list, name_value_str: $name_value_str
-    } };
-}
-
-macro_rules! ungated {
-    ($attr:ident, $typ:expr, $tpl:expr $(,)?) => {
-        (sym::$attr, $typ, $tpl, Ungated)
-    };
-}
-
-macro_rules! gated {
-    ($attr:ident, $typ:expr, $tpl:expr, $gate:ident, $msg:expr $(,)?) => {
-        (sym::$attr, $typ, $tpl, Gated(Stability::Unstable, sym::$gate, $msg, cfg_fn!($gate)))
-    };
-    ($attr:ident, $typ:expr, $tpl:expr, $msg:expr $(,)?) => {
-        (sym::$attr, $typ, $tpl, Gated(Stability::Unstable, sym::$attr, $msg, cfg_fn!($attr)))
-    };
-}
-
-macro_rules! rustc_attr {
-    (TEST, $attr:ident, $typ:expr, $tpl:expr $(,)?) => {
-        rustc_attr!(
-            $attr, $typ, $tpl,
-            concat!("the `#[", stringify!($attr), "]` attribute is just used for rustc unit tests \
-                and will never be stable",
-            ),
-        )
-    };
-    ($attr:ident, $typ:expr, $tpl:expr, $msg:expr $(,)?) => {
-        (sym::$attr, $typ, $tpl,
-         Gated(Stability::Unstable, sym::rustc_attrs, $msg, cfg_fn!(rustc_attrs)))
-    };
-}
-
-macro_rules! experimental {
-    ($attr:ident) => {
-        concat!("the `#[", stringify!($attr), "]` attribute is an experimental feature")
-    }
-}
-
-const IMPL_DETAIL: &str = "internal implementation detail";
-const INTERNAL_UNSTABLE: &str = "this is an internal attribute that will never be stable";
-
-pub type BuiltinAttribute = (Symbol, AttributeType, AttributeTemplate, AttributeGate);
-
-/// Attributes that have a special meaning to rustc or rustdoc.
-pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
-    // ==========================================================================
-    // Stable attributes:
-    // ==========================================================================
-
-    // Condtional compilation:
-    ungated!(cfg, Normal, template!(List: "predicate")),
-    ungated!(cfg_attr, Normal, template!(List: "predicate, attr1, attr2, ...")),
-
-    // Testing:
-    ungated!(ignore, Normal, template!(Word, NameValueStr: "reason")),
-    ungated!(
-        should_panic, Normal,
-        template!(Word, List: r#"expected = "reason"#, NameValueStr: "reason"),
-    ),
-    // FIXME(Centril): This can be used on stable but shouldn't.
-    ungated!(reexport_test_harness_main, Normal, template!(NameValueStr: "name")),
-
-    // Macros:
-    ungated!(derive, Normal, template!(List: "Trait1, Trait2, ...")),
-    ungated!(automatically_derived, Normal, template!(Word)),
-    // FIXME(#14407)
-    ungated!(macro_use, Normal, template!(Word, List: "name1, name2, ...")),
-    ungated!(macro_escape, Normal, template!(Word)), // Deprecated synonym for `macro_use`.
-    ungated!(macro_export, Normal, template!(Word, List: "local_inner_macros")),
-    ungated!(proc_macro, Normal, template!(Word)),
-    ungated!(
-        proc_macro_derive, Normal,
-        template!(List: "TraitName, /*opt*/ attributes(name1, name2, ...)"),
-    ),
-    ungated!(proc_macro_attribute, Normal, template!(Word)),
-
-    // Lints:
-    ungated!(warn, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
-    ungated!(allow, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
-    ungated!(forbid, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
-    ungated!(deny, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
-    ungated!(must_use, Whitelisted, template!(Word, NameValueStr: "reason")),
-    // FIXME(#14407)
-    ungated!(
-        deprecated, Normal,
-        template!(
-            Word,
-            List: r#"/*opt*/ since = "version", /*opt*/ note = "reason""#,
-            NameValueStr: "reason"
-        ),
-    ),
-
-    // Crate properties:
-    ungated!(crate_name, CrateLevel, template!(NameValueStr: "name")),
-    ungated!(crate_type, CrateLevel, template!(NameValueStr: "bin|lib|...")),
-    ungated!(crate_id, CrateLevel, template!(NameValueStr: "ignored")),
-
-    // ABI, linking, symbols, and FFI
-    ungated!(
-        link, Whitelisted,
-        template!(List: r#"name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ cfg = "...""#),
-    ),
-    ungated!(link_name, Whitelisted, template!(NameValueStr: "name")),
-    ungated!(no_link, Normal, template!(Word)),
-    ungated!(repr, Normal, template!(List: "C, packed, ...")),
-    ungated!(export_name, Whitelisted, template!(NameValueStr: "name")),
-    ungated!(link_section, Whitelisted, template!(NameValueStr: "name")),
-    ungated!(no_mangle, Whitelisted, template!(Word)),
-    ungated!(used, Whitelisted, template!(Word)),
-
-    // Limits:
-    ungated!(recursion_limit, CrateLevel, template!(NameValueStr: "N")),
-    ungated!(type_length_limit, CrateLevel, template!(NameValueStr: "N")),
-
-    // Entry point:
-    ungated!(main, Normal, template!(Word)),
-    ungated!(start, Normal, template!(Word)),
-    ungated!(no_start, CrateLevel, template!(Word)),
-    ungated!(no_main, CrateLevel, template!(Word)),
-
-    // Modules, prelude, and resolution:
-    ungated!(path, Normal, template!(NameValueStr: "file")),
-    ungated!(no_std, CrateLevel, template!(Word)),
-    ungated!(no_implicit_prelude, Normal, template!(Word)),
-    ungated!(non_exhaustive, Whitelisted, template!(Word)),
-
-    // Runtime
-    ungated!(windows_subsystem, Whitelisted, template!(NameValueStr: "windows|console")),
-    ungated!(panic_handler, Normal, template!(Word)), // RFC 2070
-
-    // Code generation:
-    ungated!(inline, Whitelisted, template!(Word, List: "always|never")),
-    ungated!(cold, Whitelisted, template!(Word)),
-    ungated!(no_builtins, Whitelisted, template!(Word)),
-    ungated!(target_feature, Whitelisted, template!(List: r#"enable = "name""#)),
-
-    // FIXME: #14408 whitelist docs since rustdoc looks at them
-    ungated!(doc, Whitelisted, template!(List: "hidden|inline|...", NameValueStr: "string")),
-
-    // ==========================================================================
-    // Unstable attributes:
-    // ==========================================================================
-
-    // Linking:
-    gated!(naked, Whitelisted, template!(Word), naked_functions, experimental!(naked)),
-    gated!(
-        link_args, Normal, template!(NameValueStr: "args"),
-        "the `link_args` attribute is experimental and not portable across platforms, \
-        it is recommended to use `#[link(name = \"foo\")] instead",
-    ),
-    gated!(
-        link_ordinal, Whitelisted, template!(List: "ordinal"), raw_dylib,
-        experimental!(link_ordinal)
-    ),
-
-    // Plugins:
-    (
-        sym::plugin_registrar, Normal, template!(Word),
-        Gated(
-            Stability::Deprecated(
-                "https://github.com/rust-lang/rust/pull/64675",
-                Some("may be removed in a future compiler version"),
-            ),
-            sym::plugin_registrar,
-            "compiler plugins are deprecated",
-            cfg_fn!(plugin_registrar)
-        )
-    ),
-    (
-        sym::plugin, CrateLevel, template!(List: "name|name(args)"),
-        Gated(
-            Stability::Deprecated(
-                "https://github.com/rust-lang/rust/pull/64675",
-                Some("may be removed in a future compiler version"),
-            ),
-            sym::plugin,
-            "compiler plugins are deprecated",
-            cfg_fn!(plugin)
-        )
-    ),
-
-    // Testing:
-    gated!(allow_fail, Normal, template!(Word), experimental!(allow_fail)),
-    gated!(
-        test_runner, CrateLevel, template!(List: "path"), custom_test_frameworks,
-        "custom test frameworks are an unstable feature",
-    ),
-    // RFC #1268
-    gated!(marker, Normal, template!(Word), marker_trait_attr, experimental!(marker)),
-    gated!(
-        thread_local, Whitelisted, template!(Word),
-        "`#[thread_local]` is an experimental feature, and does not currently handle destructors",
-    ),
-    gated!(no_core, CrateLevel, template!(Word), experimental!(no_core)),
-    // RFC 2412
-    gated!(
-        optimize, Whitelisted, template!(List: "size|speed"), optimize_attribute,
-        experimental!(optimize),
-    ),
-
-    gated!(ffi_returns_twice, Whitelisted, template!(Word), experimental!(ffi_returns_twice)),
-    gated!(track_caller, Whitelisted, template!(Word), experimental!(track_caller)),
-
-    // ==========================================================================
-    // Internal attributes: Stability, deprecation, and unsafe:
-    // ==========================================================================
-
-    ungated!(feature, CrateLevel, template!(List: "name1, name1, ...")),
-    // FIXME(#14407) -- only looked at on-demand so we can't
-    // guarantee they'll have already been checked.
-    ungated!(
-        rustc_deprecated, Whitelisted,
-        template!(List: r#"since = "version", reason = "...""#)
-    ),
-    // FIXME(#14407)
-    ungated!(stable, Whitelisted, template!(List: r#"feature = "name", since = "version""#)),
-    // FIXME(#14407)
-    ungated!(
-        unstable, Whitelisted,
-        template!(List: r#"feature = "name", reason = "...", issue = "N""#),
-    ),
-    gated!(
-        rustc_const_unstable, Normal, template!(List: r#"feature = "name""#),
-        "the `#[rustc_const_unstable]` attribute is an internal feature",
-    ),
-    gated!(
-        allow_internal_unstable, Normal, template!(Word, List: "feat1, feat2, ..."),
-        EXPLAIN_ALLOW_INTERNAL_UNSTABLE,
-    ),
-    gated!(allow_internal_unsafe, Normal, template!(Word), EXPLAIN_ALLOW_INTERNAL_UNSAFE),
-
-    // ==========================================================================
-    // Internal attributes: Type system related:
-    // ==========================================================================
-
-    gated!(fundamental, Whitelisted, template!(Word), experimental!(fundamental)),
-    gated!(
-        // RFC #1445.
-        structural_match, Whitelisted, template!(Word),
-        "the semantics of constant patterns is not yet settled",
-    ),
-    gated!(
-        may_dangle, Normal, template!(Word), dropck_eyepatch,
-        "`may_dangle` has unstable semantics and may be removed in the future",
-    ),
-
-    // ==========================================================================
-    // Internal attributes: Runtime related:
-    // ==========================================================================
-
-    rustc_attr!(rustc_allocator, Whitelisted, template!(Word), IMPL_DETAIL),
-    rustc_attr!(rustc_allocator_nounwind, Whitelisted, template!(Word), IMPL_DETAIL),
-    gated!(alloc_error_handler, Normal, template!(Word), experimental!(alloc_error_handler)),
-    gated!(
-        default_lib_allocator, Whitelisted, template!(Word), allocator_internals,
-        experimental!(default_lib_allocator),
-    ),
-    gated!(
-        needs_allocator, Normal, template!(Word), allocator_internals,
-        experimental!(needs_allocator),
-    ),
-    gated!(panic_runtime, Whitelisted, template!(Word), experimental!(panic_runtime)),
-    gated!(needs_panic_runtime, Whitelisted, template!(Word), experimental!(needs_panic_runtime)),
-    gated!(
-        unwind, Whitelisted, template!(List: "allowed|aborts"), unwind_attributes,
-        experimental!(unwind),
-    ),
-    gated!(
-        compiler_builtins, Whitelisted, template!(Word),
-        "the `#[compiler_builtins]` attribute is used to identify the `compiler_builtins` crate \
-        which contains compiler-rt intrinsics and will never be stable",
-    ),
-    gated!(
-        sanitizer_runtime, Whitelisted, template!(Word),
-        "the `#[sanitizer_runtime]` attribute is used to identify crates that contain the runtime \
-        of a sanitizer and will never be stable",
-    ),
-    gated!(
-        profiler_runtime, Whitelisted, template!(Word),
-        "the `#[profiler_runtime]` attribute is used to identify the `profiler_builtins` crate \
-        which contains the profiler runtime and will never be stable",
-    ),
-
-    // ==========================================================================
-    // Internal attributes, Linkage:
-    // ==========================================================================
-
-    gated!(
-        linkage, Whitelisted, template!(NameValueStr: "external|internal|..."),
-        "the `linkage` attribute is experimental and not portable across platforms",
-    ),
-    rustc_attr!(rustc_std_internal_symbol, Whitelisted, template!(Word), INTERNAL_UNSTABLE),
-
-    // ==========================================================================
-    // Internal attributes, Macro related:
-    // ==========================================================================
-
-    rustc_attr!(rustc_builtin_macro, Whitelisted, template!(Word), IMPL_DETAIL),
-    rustc_attr!(rustc_proc_macro_decls, Normal, template!(Word), INTERNAL_UNSTABLE),
-    rustc_attr!(
-        rustc_macro_transparency, Whitelisted,
-        template!(NameValueStr: "transparent|semitransparent|opaque"),
-        "used internally for testing macro hygiene",
-    ),
-
-    // ==========================================================================
-    // Internal attributes, Diagnostics related:
-    // ==========================================================================
-
-    rustc_attr!(
-        rustc_on_unimplemented, Whitelisted,
-        template!(
-            List: r#"/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...""#,
-            NameValueStr: "message"
-        ),
-        INTERNAL_UNSTABLE
-    ),
-    // Whitelists "identity-like" conversion methods to suggest on type mismatch.
-    rustc_attr!(rustc_conversion_suggestion, Whitelisted, template!(Word), INTERNAL_UNSTABLE),
-
-    // ==========================================================================
-    // Internal attributes, Const related:
-    // ==========================================================================
-
-    rustc_attr!(rustc_promotable, Whitelisted, template!(Word), IMPL_DETAIL),
-    rustc_attr!(rustc_allow_const_fn_ptr, Whitelisted, template!(Word), IMPL_DETAIL),
-    rustc_attr!(rustc_args_required_const, Whitelisted, template!(List: "N"), INTERNAL_UNSTABLE),
-
-    // ==========================================================================
-    // Internal attributes, Layout related:
-    // ==========================================================================
-
-    rustc_attr!(
-        rustc_layout_scalar_valid_range_start, Whitelisted, template!(List: "value"),
-        "the `#[rustc_layout_scalar_valid_range_start]` attribute is just used to enable \
-        niche optimizations in libcore and will never be stable",
-    ),
-    rustc_attr!(
-        rustc_layout_scalar_valid_range_end, Whitelisted, template!(List: "value"),
-        "the `#[rustc_layout_scalar_valid_range_end]` attribute is just used to enable \
-        niche optimizations in libcore and will never be stable",
-    ),
-    rustc_attr!(
-        rustc_nonnull_optimization_guaranteed, Whitelisted, template!(Word),
-        "the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to enable \
-        niche optimizations in libcore and will never be stable",
-    ),
-
-    // ==========================================================================
-    // Internal attributes, Misc:
-    // ==========================================================================
-    gated!(
-        lang, Normal, template!(NameValueStr: "name"), lang_items,
-        "language items are subject to change",
-    ),
-    (
-        sym::rustc_diagnostic_item,
-        Normal,
-        template!(NameValueStr: "name"),
-        Gated(
-            Stability::Unstable,
-            sym::rustc_attrs,
-            "diagnostic items compiler internal support for linting",
-            cfg_fn!(rustc_attrs),
-        ),
-    ),
-    (
-        sym::no_debug, Whitelisted, template!(Word),
-        Gated(
-            Stability::Deprecated("https://github.com/rust-lang/rust/issues/29721", None),
-            sym::no_debug,
-            "the `#[no_debug]` attribute was an experimental feature that has been \
-            deprecated due to lack of demand",
-            cfg_fn!(no_debug)
-        )
-    ),
-    gated!(
-        // Used in resolve:
-        prelude_import, Whitelisted, template!(Word),
-        "`#[prelude_import]` is for use by rustc only",
-    ),
-    gated!(
-        rustc_paren_sugar, Normal, template!(Word), unboxed_closures,
-        "unboxed_closures are still evolving",
-    ),
-    rustc_attr!(
-        rustc_inherit_overflow_checks, Whitelisted, template!(Word),
-        "the `#[rustc_inherit_overflow_checks]` attribute is just used to control \
-        overflow checking behavior of several libcore functions that are inlined \
-        across crates and will never be stable",
-    ),
-    rustc_attr!(rustc_reservation_impl, Normal, template!(NameValueStr: "reservation message"),
-                "the `#[rustc_reservation_impl]` attribute is internally used \
-                 for reserving for `for<T> From<!> for T` impl"
-    ),
-    rustc_attr!(
-        rustc_test_marker, Normal, template!(Word),
-        "the `#[rustc_test_marker]` attribute is used internally to track tests",
-    ),
-
-    // ==========================================================================
-    // Internal attributes, Testing:
-    // ==========================================================================
-
-    rustc_attr!(TEST, rustc_outlives, Normal, template!(Word)),
-    rustc_attr!(TEST, rustc_variance, Normal, template!(Word)),
-    rustc_attr!(TEST, rustc_layout, Normal, template!(List: "field1, field2, ...")),
-    rustc_attr!(TEST, rustc_regions, Normal, template!(Word)),
-    rustc_attr!(TEST, rustc_error, Whitelisted, template!(Word)),
-    rustc_attr!(TEST, rustc_dump_user_substs, Whitelisted, template!(Word)),
-    rustc_attr!(TEST, rustc_if_this_changed, Whitelisted, template!(Word, List: "DepNode")),
-    rustc_attr!(TEST, rustc_then_this_would_need, Whitelisted, template!(List: "DepNode")),
-    rustc_attr!(
-        TEST, rustc_dirty, Whitelisted,
-        template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#),
-    ),
-    rustc_attr!(
-        TEST, rustc_clean, Whitelisted,
-        template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#),
-    ),
-    rustc_attr!(
-        TEST, rustc_partition_reused, Whitelisted,
-        template!(List: r#"cfg = "...", module = "...""#),
-    ),
-    rustc_attr!(
-        TEST, rustc_partition_codegened, Whitelisted,
-        template!(List: r#"cfg = "...", module = "...""#),
-    ),
-    rustc_attr!(
-        TEST, rustc_expected_cgu_reuse, Whitelisted,
-        template!(List: r#"cfg = "...", module = "...", kind = "...""#),
-    ),
-    rustc_attr!(TEST, rustc_synthetic, Whitelisted, template!(Word)),
-    rustc_attr!(TEST, rustc_symbol_name, Whitelisted, template!(Word)),
-    rustc_attr!(TEST, rustc_def_path, Whitelisted, template!(Word)),
-    rustc_attr!(TEST, rustc_mir, Whitelisted, template!(List: "arg1, arg2, ...")),
-    rustc_attr!(TEST, rustc_dump_program_clauses, Whitelisted, template!(Word)),
-    rustc_attr!(TEST, rustc_dump_env_program_clauses, Whitelisted, template!(Word)),
-    rustc_attr!(TEST, rustc_object_lifetime_default, Whitelisted, template!(Word)),
-    rustc_attr!(TEST, rustc_dummy, Normal, template!(Word /* doesn't matter*/)),
-    gated!(
-        omit_gdb_pretty_printer_section, Whitelisted, template!(Word),
-        "the `#[omit_gdb_pretty_printer_section]` attribute is just used for the Rust test suite",
-    ),
-];
-
-pub fn deprecated_attributes() -> Vec<&'static BuiltinAttribute> {
-    BUILTIN_ATTRIBUTES.iter().filter(|(.., gate)| gate.is_deprecated()).collect()
-}
-
-pub fn is_builtin_attr_name(name: ast::Name) -> bool {
-    BUILTIN_ATTRIBUTE_MAP.get(&name).is_some()
-}
-
-pub fn is_builtin_attr(attr: &ast::Attribute) -> bool {
-    attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name)).is_some()
-}
-
-lazy_static! {
-    pub static ref BUILTIN_ATTRIBUTE_MAP: FxHashMap<Symbol, &'static BuiltinAttribute> = {
-        let mut map = FxHashMap::default();
-        for attr in BUILTIN_ATTRIBUTES.iter() {
-            if map.insert(attr.0, attr).is_some() {
-                panic!("duplicate builtin attribute `{}`", attr.0);
-            }
-        }
-        map
-    };
-}
diff --git a/src/libsyntax/feature_gate/check.rs b/src/libsyntax/feature_gate/check.rs
index ecff89ad59b..3d2c3b1d4f9 100644
--- a/src/libsyntax/feature_gate/check.rs
+++ b/src/libsyntax/feature_gate/check.rs
@@ -1,35 +1,23 @@
-use super::{active::{ACTIVE_FEATURES, Features}, Feature, State as FeatureState};
-use super::accepted::ACCEPTED_FEATURES;
-use super::removed::{REMOVED_FEATURES, STABLE_REMOVED_FEATURES};
-use super::builtin_attrs::{AttributeGate, BUILTIN_ATTRIBUTE_MAP};
-
-use crate::ast::{
-    self, AssocTyConstraint, AssocTyConstraintKind, NodeId, GenericParam, GenericParamKind,
-    PatKind, RangeEnd, VariantData,
-};
-use crate::attr::{self, check_builtin_attribute};
+use rustc_feature::{ACCEPTED_FEATURES, ACTIVE_FEATURES, REMOVED_FEATURES, STABLE_REMOVED_FEATURES};
+use rustc_feature::{AttributeGate, BUILTIN_ATTRIBUTE_MAP};
+use rustc_feature::{Features, Feature, State as FeatureState, UnstableFeatures};
+use rustc_feature::{find_feature_issue, GateIssue};
+
+use crate::ast::{self, AssocTyConstraint, AssocTyConstraintKind, NodeId};
+use crate::ast::{GenericParam, GenericParamKind, PatKind, RangeEnd, VariantData};
+use crate::attr;
 use crate::source_map::Spanned;
 use crate::edition::{ALL_EDITIONS, Edition};
 use crate::visit::{self, FnKind, Visitor};
-use crate::token;
 use crate::sess::ParseSess;
 use crate::symbol::{Symbol, sym};
-use crate::tokenstream::TokenTree;
 
 use errors::{Applicability, DiagnosticBuilder, Handler};
 use rustc_data_structures::fx::FxHashMap;
 use syntax_pos::{Span, DUMMY_SP, MultiSpan};
 use log::debug;
 
-use std::env;
-
-#[derive(Copy, Clone, Debug)]
-pub enum Stability {
-    Unstable,
-    // First argument is tracking issue link; second argument is an optional
-    // help message, which defaults to "remove this attribute"
-    Deprecated(&'static str, Option<&'static str>),
-}
+use rustc_error_codes::*;
 
 macro_rules! gate_feature_fn {
     ($cx: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr, $level: expr) => {{
@@ -59,27 +47,6 @@ pub fn check_attribute(attr: &ast::Attribute, parse_sess: &ParseSess, features:
     PostExpansionVisitor { parse_sess, features }.visit_attribute(attr)
 }
 
-fn find_lang_feature_issue(feature: Symbol) -> Option<u32> {
-    if let Some(info) = ACTIVE_FEATURES.iter().find(|t| t.name == feature) {
-        // FIXME (#28244): enforce that active features have issue numbers
-        // assert!(info.issue.is_some())
-        info.issue
-    } else {
-        // search in Accepted, Removed, or Stable Removed features
-        let found = ACCEPTED_FEATURES.iter().chain(REMOVED_FEATURES).chain(STABLE_REMOVED_FEATURES)
-            .find(|t| t.name == feature);
-        match found {
-            Some(&Feature { issue, .. }) => issue,
-            None => panic!("Feature `{}` is not declared anywhere", feature),
-        }
-    }
-}
-
-pub enum GateIssue {
-    Language,
-    Library(Option<u32>)
-}
-
 #[derive(Debug, Copy, Clone, PartialEq)]
 pub enum GateStrength {
     /// A hard error. (Most feature gates should use this.)
@@ -88,41 +55,35 @@ pub enum GateStrength {
     Soft,
 }
 
-pub fn emit_feature_err(
-    sess: &ParseSess,
+pub fn feature_err<'a>(
+    sess: &'a ParseSess,
     feature: Symbol,
-    span: Span,
-    issue: GateIssue,
+    span: impl Into<MultiSpan>,
     explain: &str,
-) {
-    feature_err(sess, feature, span, issue, explain).emit();
+) -> DiagnosticBuilder<'a> {
+    feature_err_issue(sess, feature, span, GateIssue::Language, explain)
 }
 
-pub fn feature_err<'a, S: Into<MultiSpan>>(
+pub fn feature_err_issue<'a>(
     sess: &'a ParseSess,
     feature: Symbol,
-    span: S,
+    span: impl Into<MultiSpan>,
     issue: GateIssue,
     explain: &str,
 ) -> DiagnosticBuilder<'a> {
     leveled_feature_err(sess, feature, span, issue, explain, GateStrength::Hard)
 }
 
-fn leveled_feature_err<'a, S: Into<MultiSpan>>(
+fn leveled_feature_err<'a>(
     sess: &'a ParseSess,
     feature: Symbol,
-    span: S,
+    span: impl Into<MultiSpan>,
     issue: GateIssue,
     explain: &str,
     level: GateStrength,
 ) -> DiagnosticBuilder<'a> {
     let diag = &sess.span_diagnostic;
 
-    let issue = match issue {
-        GateIssue::Language => find_lang_feature_issue(feature),
-        GateIssue::Library(lib) => lib,
-    };
-
     let mut err = match level {
         GateStrength::Hard => {
             diag.struct_span_err_with_code(span, explain, stringify_error_code!(E0658))
@@ -130,14 +91,11 @@ fn leveled_feature_err<'a, S: Into<MultiSpan>>(
         GateStrength::Soft => diag.struct_span_warn(span, explain),
     };
 
-    match issue {
-        None | Some(0) => {}  // We still accept `0` as a stand-in for backwards compatibility
-        Some(n) => {
-            err.note(&format!(
-                "for more information, see https://github.com/rust-lang/rust/issues/{}",
-                n,
-            ));
-        }
+    if let Some(n) = find_feature_issue(feature, issue) {
+        err.note(&format!(
+            "for more information, see https://github.com/rust-lang/rust/issues/{}",
+            n,
+        ));
     }
 
     // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
@@ -156,20 +114,6 @@ fn leveled_feature_err<'a, S: Into<MultiSpan>>(
 
 }
 
-const EXPLAIN_BOX_SYNTAX: &str =
-    "box expression syntax is experimental; you can call `Box::new` instead";
-
-pub const EXPLAIN_STMT_ATTR_SYNTAX: &str =
-    "attributes on expressions are experimental";
-
-pub const EXPLAIN_ALLOW_INTERNAL_UNSTABLE: &str =
-    "allow_internal_unstable side-steps feature gating and stability checks";
-pub const EXPLAIN_ALLOW_INTERNAL_UNSAFE: &str =
-    "allow_internal_unsafe side-steps the unsafe_code lint";
-
-pub const EXPLAIN_UNSIZED_TUPLE_COERCION: &str =
-    "unsized tuple coercion is not stable enough for use and is subject to change";
-
 struct PostExpansionVisitor<'a> {
     parse_sess: &'a ParseSess,
     features: &'a Features,
@@ -191,10 +135,10 @@ macro_rules! gate_feature_post {
 }
 
 impl<'a> PostExpansionVisitor<'a> {
-    fn check_abi(&self, abi: ast::Abi) {
-        let ast::Abi { symbol, span } = abi;
+    fn check_abi(&self, abi: ast::StrLit) {
+        let ast::StrLit { symbol_unescaped, span, .. } = abi;
 
-        match &*symbol.as_str() {
+        match &*symbol_unescaped.as_str() {
             // Stable
             "Rust" |
             "C" |
@@ -258,6 +202,12 @@ impl<'a> PostExpansionVisitor<'a> {
         }
     }
 
+    fn check_extern(&self, ext: ast::Extern) {
+        if let ast::Extern::Explicit(abi) = ext {
+            self.check_abi(abi);
+        }
+    }
+
     fn maybe_report_invalid_custom_discriminants(&self, variants: &[ast::Variant]) {
         let has_fields = variants.iter().any(|variant| match variant.data {
             VariantData::Tuple(..) | VariantData::Struct(..) => true,
@@ -276,7 +226,6 @@ impl<'a> PostExpansionVisitor<'a> {
                 self.parse_sess,
                 sym::arbitrary_enum_discriminant,
                 discriminant_spans.clone(),
-                crate::feature_gate::GateIssue::Language,
                 "custom discriminant values are not allowed in enums with tuple or struct variants",
             );
             for sp in discriminant_spans {
@@ -321,6 +270,27 @@ impl<'a> PostExpansionVisitor<'a> {
             );
         }
     }
+
+    /// Feature gate `impl Trait` inside `type Alias = $type_expr;`.
+    fn check_impl_trait(&self, ty: &ast::Ty) {
+        struct ImplTraitVisitor<'a> {
+            vis: &'a PostExpansionVisitor<'a>,
+        }
+        impl Visitor<'_> for ImplTraitVisitor<'_> {
+            fn visit_ty(&mut self, ty: &ast::Ty) {
+                if let ast::TyKind::ImplTrait(..) = ty.kind {
+                    gate_feature_post!(
+                        &self.vis,
+                        type_alias_impl_trait,
+                        ty.span,
+                        "`impl Trait` in type aliases is unstable"
+                    );
+                }
+                visit::walk_ty(self, ty);
+            }
+        }
+        ImplTraitVisitor { vis: self }.visit_ty(ty);
+    }
 }
 
 impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
@@ -331,19 +301,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
         if let Some((.., AttributeGate::Gated(_, name, descr, has_feature))) = attr_info {
             gate_feature_fn!(self, has_feature, attr.span, name, descr, GateStrength::Hard);
         }
-        // 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(self.parse_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.
-                    attr.parse_meta(self.parse_sess).map_err(|mut err| err.emit()).ok();
-                }
-            }
-        }
         // Check unstable flavors of the `#[doc]` attribute.
         if attr.check_name(sym::doc) {
             for nested_meta in attr.meta_item_list().unwrap_or_default() {
@@ -380,7 +337,9 @@ 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);
+                if let Some(abi) = foreign_module.abi {
+                    self.check_abi(abi);
+                }
             }
 
             ast::ItemKind::Fn(..) => {
@@ -468,14 +427,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 gate_feature_post!(&self, decl_macro, i.span, msg);
             }
 
-            ast::ItemKind::OpaqueTy(..) => {
-                gate_feature_post!(
-                    &self,
-                    type_alias_impl_trait,
-                    i.span,
-                    "`impl Trait` in type aliases is unstable"
-                );
-            }
+            ast::ItemKind::TyAlias(ref ty, ..) => self.check_impl_trait(&ty),
 
             _ => {}
         }
@@ -510,31 +462,20 @@ 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);
-            }
-            ast::TyKind::Never => {
-                gate_feature_post!(&self, never_type, ty.span,
-                                   "The `!` type is experimental");
+                self.check_extern(bare_fn_ty.ext);
             }
             _ => {}
         }
         visit::walk_ty(self, ty)
     }
 
-    fn visit_fn_ret_ty(&mut self, ret_ty: &'a ast::FunctionRetTy) {
-        if let ast::FunctionRetTy::Ty(ref output_ty) = *ret_ty {
-            if let ast::TyKind::Never = output_ty.kind {
-                // Do nothing.
-            } else {
-                self.visit_ty(output_ty)
-            }
-        }
-    }
-
     fn visit_expr(&mut self, e: &'a ast::Expr) {
         match e.kind {
             ast::ExprKind::Box(_) => {
-                gate_feature_post!(&self, box_syntax, e.span, EXPLAIN_BOX_SYNTAX);
+                gate_feature_post!(
+                    &self, box_syntax, e.span,
+                    "box expression syntax is experimental; you can call `Box::new` instead"
+                );
             }
             ast::ExprKind::Type(..) => {
                 // To avoid noise about type ascription in common syntax errors, only emit if it
@@ -558,10 +499,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
         visit::walk_expr(self, e)
     }
 
-    fn visit_arm(&mut self, arm: &'a ast::Arm) {
-        visit::walk_arm(self, arm)
-    }
-
     fn visit_pat(&mut self, pattern: &'a ast::Pat) {
         match &pattern.kind {
             PatKind::Slice(pats) => {
@@ -604,7 +541,7 @@ 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);
+            self.check_extern(header.ext);
         }
 
         if fn_decl.c_variadic() {
@@ -638,7 +575,7 @@ 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);
+                    self.check_extern(sig.header.ext);
                 }
                 if sig.decl.c_variadic() {
                     gate_feature_post!(&self, c_variadic, ti.span,
@@ -649,9 +586,8 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 }
             }
             ast::TraitItemKind::Type(_, ref default) => {
-                // We use three if statements instead of something like match guards so that all
-                // of these errors can be emitted if all cases apply.
-                if default.is_some() {
+                if let Some(ty) = default {
+                    self.check_impl_trait(ty);
                     gate_feature_post!(&self, associated_type_defaults, ti.span,
                                        "associated type defaults are unstable");
                 }
@@ -676,15 +612,8 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                                        "C-variadic functions are unstable");
                 }
             }
-            ast::ImplItemKind::OpaqueTy(..) => {
-                gate_feature_post!(
-                    &self,
-                    type_alias_impl_trait,
-                    ii.span,
-                    "`impl Trait` in type aliases is unstable"
-                );
-            }
-            ast::ImplItemKind::TyAlias(_) => {
+            ast::ImplItemKind::TyAlias(ref ty) => {
+                self.check_impl_trait(ty);
                 self.check_gat(&ii.generics, ii.span);
             }
             _ => {}
@@ -705,15 +634,14 @@ pub fn get_features(span_handler: &Handler, krate_attrs: &[ast::Attribute],
                     crate_edition: Edition, allow_features: &Option<Vec<String>>) -> Features {
     fn feature_removed(span_handler: &Handler, span: Span, reason: Option<&str>) {
         let mut err = struct_span_err!(span_handler, span, E0557, "feature has been removed");
+        err.span_label(span, "feature has been removed");
         if let Some(reason) = reason {
-            err.span_note(span, reason);
-        } else {
-            err.span_label(span, "feature has been removed");
+            err.note(reason);
         }
         err.emit();
     }
 
-    let mut features = Features::new();
+    let mut features = Features::default();
     let mut edition_enabled_features = FxHashMap::default();
 
     for &edition in ALL_EDITIONS {
@@ -883,6 +811,7 @@ pub fn check_crate(krate: &ast::Crate,
     gate_all!(generators, "yield syntax is experimental");
     gate_all!(or_patterns, "or-patterns syntax is experimental");
     gate_all!(const_extern_fn, "`const extern fn` definitions are unstable");
+    gate_all!(raw_ref_op, "raw address of syntax is experimental");
 
     // All uses of `gate_all!` below this point were added in #65742,
     // and subsequently disabled (with the non-early gating readded).
@@ -917,40 +846,6 @@ pub fn check_crate(krate: &ast::Crate,
     visit::walk_crate(&mut visitor, krate);
 }
 
-#[derive(Clone, Copy, Hash)]
-pub enum UnstableFeatures {
-    /// Hard errors for unstable features are active, as on beta/stable channels.
-    Disallow,
-    /// Allow features to be activated, as on nightly.
-    Allow,
-    /// Errors are bypassed for bootstrapping. This is required any time
-    /// during the build that feature-related lints are set to warn or above
-    /// because the build turns on warnings-as-errors and uses lots of unstable
-    /// features. As a result, this is always required for building Rust itself.
-    Cheat
-}
-
-impl UnstableFeatures {
-    pub fn from_environment() -> UnstableFeatures {
-        // `true` if this is a feature-staged build, i.e., on the beta or stable channel.
-        let disable_unstable_features = option_env!("CFG_DISABLE_UNSTABLE_FEATURES").is_some();
-        // `true` if we should enable unstable features for bootstrapping.
-        let bootstrap = env::var("RUSTC_BOOTSTRAP").is_ok();
-        match (disable_unstable_features, bootstrap) {
-            (_, true) => UnstableFeatures::Cheat,
-            (true, _) => UnstableFeatures::Disallow,
-            (false, _) => UnstableFeatures::Allow
-        }
-    }
-
-    pub fn is_nightly_build(&self) -> bool {
-        match *self {
-            UnstableFeatures::Allow | UnstableFeatures::Cheat => true,
-            UnstableFeatures::Disallow => false,
-        }
-    }
-}
-
 fn maybe_stage_features(span_handler: &Handler, krate: &ast::Crate, unstable: UnstableFeatures) {
     if !unstable.is_nightly_build() {
         for attr in krate.attrs.iter().filter(|attr| attr.check_name(sym::feature)) {
diff --git a/src/libsyntax/feature_gate/mod.rs b/src/libsyntax/feature_gate/mod.rs
deleted file mode 100644
index ba970618c0e..00000000000
--- a/src/libsyntax/feature_gate/mod.rs
+++ /dev/null
@@ -1,64 +0,0 @@
-//! # Feature gating
-//!
-//! This module implements the gating necessary for preventing certain compiler
-//! features from being used by default. This module will crawl a pre-expanded
-//! AST to ensure that there are no features which are used that are not
-//! enabled.
-//!
-//! Features are enabled in programs via the crate-level attributes of
-//! `#![feature(...)]` with a comma-separated list of features.
-//!
-//! For the purpose of future feature-tracking, once code for detection of feature
-//! gate usage is added, *do not remove it again* even once the feature
-//! becomes stable.
-
-mod accepted;
-mod removed;
-mod active;
-mod builtin_attrs;
-mod check;
-
-use std::fmt;
-use crate::{edition::Edition, symbol::Symbol};
-use syntax_pos::Span;
-
-#[derive(Clone, Copy)]
-pub enum State {
-    Accepted,
-    Active { set: fn(&mut Features, Span) },
-    Removed { reason: Option<&'static str> },
-    Stabilized { reason: Option<&'static str> },
-}
-
-impl fmt::Debug for State {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            State::Accepted { .. } => write!(f, "accepted"),
-            State::Active { .. } => write!(f, "active"),
-            State::Removed { .. } => write!(f, "removed"),
-            State::Stabilized { .. } => write!(f, "stabilized"),
-        }
-    }
-}
-
-#[derive(Debug, Clone)]
-pub struct Feature {
-    state: State,
-    name: Symbol,
-    since: &'static str,
-    issue: Option<u32>,
-    edition: Option<Edition>,
-    description: &'static str,
-}
-
-pub use active::{Features, INCOMPLETE_FEATURES};
-pub use builtin_attrs::{
-    AttributeGate, AttributeType, GatedCfg,
-    BuiltinAttribute, BUILTIN_ATTRIBUTES, BUILTIN_ATTRIBUTE_MAP,
-    deprecated_attributes, is_builtin_attr,  is_builtin_attr_name,
-};
-pub use check::{
-    check_crate, check_attribute, get_features, feature_err, emit_feature_err,
-    Stability, GateIssue, UnstableFeatures,
-    EXPLAIN_STMT_ATTR_SYNTAX, EXPLAIN_UNSIZED_TUPLE_COERCION,
-};
diff --git a/src/libsyntax/feature_gate/removed.rs b/src/libsyntax/feature_gate/removed.rs
deleted file mode 100644
index c7b931a6f70..00000000000
--- a/src/libsyntax/feature_gate/removed.rs
+++ /dev/null
@@ -1,113 +0,0 @@
-//! List of the removed feature gates.
-
-use crate::symbol::sym;
-use super::{State, Feature};
-
-macro_rules! declare_features {
-    ($(
-        $(#[doc = $doc:tt])* (removed, $feature:ident, $ver:expr, $issue:expr, None, $reason:expr),
-    )+) => {
-        /// Represents unstable features which have since been removed (it was once Active)
-        pub const REMOVED_FEATURES: &[Feature] = &[
-            $(
-                Feature {
-                    state: State::Removed { reason: $reason },
-                    name: sym::$feature,
-                    since: $ver,
-                    issue: $issue,
-                    edition: None,
-                    description: concat!($($doc,)*),
-                }
-            ),+
-        ];
-    };
-
-    ($(
-        $(#[doc = $doc:tt])* (stable_removed, $feature:ident, $ver:expr, $issue:expr, None),
-    )+) => {
-        /// Represents stable features which have since been removed (it was once Accepted)
-        pub const STABLE_REMOVED_FEATURES: &[Feature] = &[
-            $(
-                Feature {
-                    state: State::Stabilized { reason: None },
-                    name: sym::$feature,
-                    since: $ver,
-                    issue: $issue,
-                    edition: None,
-                    description: concat!($($doc,)*),
-                }
-            ),+
-        ];
-    };
-}
-
-declare_features! (
-    // -------------------------------------------------------------------------
-    // feature-group-start: removed features
-    // -------------------------------------------------------------------------
-
-    (removed, import_shadowing, "1.0.0", None, None, None),
-    (removed, managed_boxes, "1.0.0", None, None, None),
-    /// Allows use of unary negate on unsigned integers, e.g., -e for e: u8
-    (removed, negate_unsigned, "1.0.0", Some(29645), None, None),
-    (removed, reflect, "1.0.0", Some(27749), None, None),
-    /// A way to temporarily opt out of opt in copy. This will *never* be accepted.
-    (removed, opt_out_copy, "1.0.0", None, None, None),
-    (removed, quad_precision_float, "1.0.0", None, None, None),
-    (removed, struct_inherit, "1.0.0", None, None, None),
-    (removed, test_removed_feature, "1.0.0", None, None, None),
-    (removed, visible_private_types, "1.0.0", None, None, None),
-    (removed, unsafe_no_drop_flag, "1.0.0", None, None, None),
-    /// Allows using items which are missing stability attributes
-    (removed, unmarked_api, "1.0.0", None, None, None),
-    (removed, allocator, "1.0.0", None, None, None),
-    (removed, simd, "1.0.0", Some(27731), None,
-     Some("removed in favor of `#[repr(simd)]`")),
-    (removed, advanced_slice_patterns, "1.0.0", Some(62254), None,
-     Some("merged into `#![feature(slice_patterns)]`")),
-    (removed, macro_reexport, "1.0.0", Some(29638), None,
-     Some("subsumed by `pub use`")),
-    (removed, pushpop_unsafe, "1.2.0", None, None, None),
-    (removed, needs_allocator, "1.4.0", Some(27389), None,
-     Some("subsumed by `#![feature(allocator_internals)]`")),
-    (removed, proc_macro_mod, "1.27.0", Some(54727), None,
-     Some("subsumed by `#![feature(proc_macro_hygiene)]`")),
-    (removed, proc_macro_expr, "1.27.0", Some(54727), None,
-     Some("subsumed by `#![feature(proc_macro_hygiene)]`")),
-    (removed, proc_macro_non_items, "1.27.0", Some(54727), None,
-     Some("subsumed by `#![feature(proc_macro_hygiene)]`")),
-    (removed, proc_macro_gen, "1.27.0", Some(54727), None,
-     Some("subsumed by `#![feature(proc_macro_hygiene)]`")),
-    (removed, panic_implementation, "1.28.0", Some(44489), None,
-     Some("subsumed by `#[panic_handler]`")),
-    /// Allows the use of `#[derive(Anything)]` as sugar for `#[derive_Anything]`.
-    (removed, custom_derive, "1.32.0", Some(29644), None,
-     Some("subsumed by `#[proc_macro_derive]`")),
-    /// Paths of the form: `extern::foo::bar`
-    (removed, extern_in_paths, "1.33.0", Some(55600), None,
-     Some("subsumed by `::foo::bar` paths")),
-    (removed, quote, "1.33.0", Some(29601), None, None),
-    /// Allows using `#[unsafe_destructor_blind_to_params]` (RFC 1238).
-    (removed, dropck_parametricity, "1.38.0", Some(28498), None, None),
-    (removed, await_macro, "1.38.0", Some(50547), None,
-     Some("subsumed by `.await` syntax")),
-    /// Allows defining `existential type`s.
-    (removed, existential_type, "1.38.0", Some(63063), None,
-     Some("removed in favor of `#![feature(type_alias_impl_trait)]`")),
-    /// Allows using the macros:
-    /// + `__diagnostic_used`
-    /// + `__register_diagnostic`
-    /// +`__build_diagnostic_array`
-    (removed, rustc_diagnostic_macros, "1.38.0", None, None, None),
-    /// Allows using `#[on_unimplemented(..)]` on traits.
-    /// (Moved to `rustc_attrs`.)
-    (removed, on_unimplemented, "1.40.0", None, None, None),
-
-    // -------------------------------------------------------------------------
-    // feature-group-end: removed features
-    // -------------------------------------------------------------------------
-);
-
-declare_features! (
-    (stable_removed, no_stack_check, "1.0.0", None, None),
-);
diff --git a/src/libsyntax/json.rs b/src/libsyntax/json.rs
deleted file mode 100644
index 0b157938375..00000000000
--- a/src/libsyntax/json.rs
+++ /dev/null
@@ -1,434 +0,0 @@
-//! A JSON emitter for errors.
-//!
-//! This works by converting errors to a simplified structural format (see the
-//! structs at the start of the file) and then serializing them. These should
-//! contain as much information about the error as possible.
-//!
-//! The format of the JSON output should be considered *unstable*. For now the
-//! structs at the end of this file (Diagnostic*) specify the error format.
-
-// FIXME: spec the JSON output properly.
-
-use crate::source_map::{SourceMap, FilePathMapping};
-
-use errors::registry::Registry;
-use errors::{SubDiagnostic, CodeSuggestion, SourceMapper, SourceMapperDyn};
-use errors::{DiagnosticId, Applicability};
-use errors::emitter::{Emitter, HumanReadableErrorType};
-
-use syntax_pos::{MacroBacktrace, Span, SpanLabel, MultiSpan};
-use rustc_data_structures::sync::{self, Lrc};
-use std::io::{self, Write};
-use std::path::Path;
-use std::vec;
-use std::sync::{Arc, Mutex};
-
-use rustc_serialize::json::{as_json, as_pretty_json};
-
-#[cfg(test)]
-mod tests;
-
-pub struct JsonEmitter {
-    dst: Box<dyn Write + Send>,
-    registry: Option<Registry>,
-    sm: Lrc<dyn SourceMapper + sync::Send + sync::Sync>,
-    pretty: bool,
-    ui_testing: bool,
-    json_rendered: HumanReadableErrorType,
-    external_macro_backtrace: bool,
-}
-
-impl JsonEmitter {
-    pub fn stderr(
-        registry: Option<Registry>,
-        source_map: Lrc<SourceMap>,
-        pretty: bool,
-        json_rendered: HumanReadableErrorType,
-        external_macro_backtrace: bool,
-    ) -> JsonEmitter {
-        JsonEmitter {
-            dst: Box::new(io::stderr()),
-            registry,
-            sm: source_map,
-            pretty,
-            ui_testing: false,
-            json_rendered,
-            external_macro_backtrace,
-        }
-    }
-
-    pub fn basic(
-        pretty: bool,
-        json_rendered: HumanReadableErrorType,
-        external_macro_backtrace: bool,
-    ) -> JsonEmitter {
-        let file_path_mapping = FilePathMapping::empty();
-        JsonEmitter::stderr(None, Lrc::new(SourceMap::new(file_path_mapping)),
-                            pretty, json_rendered, external_macro_backtrace)
-    }
-
-    pub fn new(
-        dst: Box<dyn Write + Send>,
-        registry: Option<Registry>,
-        source_map: Lrc<SourceMap>,
-        pretty: bool,
-        json_rendered: HumanReadableErrorType,
-        external_macro_backtrace: bool,
-    ) -> JsonEmitter {
-        JsonEmitter {
-            dst,
-            registry,
-            sm: source_map,
-            pretty,
-            ui_testing: false,
-            json_rendered,
-            external_macro_backtrace,
-        }
-    }
-
-    pub fn ui_testing(self, ui_testing: bool) -> Self {
-        Self { ui_testing, ..self }
-    }
-}
-
-impl Emitter for JsonEmitter {
-    fn emit_diagnostic(&mut self, diag: &errors::Diagnostic) {
-        let data = Diagnostic::from_errors_diagnostic(diag, self);
-        let result = if self.pretty {
-            writeln!(&mut self.dst, "{}", as_pretty_json(&data))
-        } else {
-            writeln!(&mut self.dst, "{}", as_json(&data))
-        };
-        if let Err(e) = result {
-            panic!("failed to print diagnostics: {:?}", e);
-        }
-    }
-
-    fn emit_artifact_notification(&mut self, path: &Path, artifact_type: &str) {
-        let data = ArtifactNotification { artifact: path, emit: artifact_type };
-        let result = if self.pretty {
-            writeln!(&mut self.dst, "{}", as_pretty_json(&data))
-        } else {
-            writeln!(&mut self.dst, "{}", as_json(&data))
-        };
-        if let Err(e) = result {
-            panic!("failed to print notification: {:?}", e);
-        }
-    }
-
-    fn source_map(&self) -> Option<&Lrc<SourceMapperDyn>> {
-        Some(&self.sm)
-    }
-
-    fn should_show_explain(&self) -> bool {
-        match self.json_rendered {
-            HumanReadableErrorType::Short(_) => false,
-            _ => true,
-        }
-    }
-}
-
-// The following data types are provided just for serialisation.
-
-#[derive(RustcEncodable)]
-struct Diagnostic {
-    /// The primary error message.
-    message: String,
-    code: Option<DiagnosticCode>,
-    /// "error: internal compiler error", "error", "warning", "note", "help".
-    level: &'static str,
-    spans: Vec<DiagnosticSpan>,
-    /// Associated diagnostic messages.
-    children: Vec<Diagnostic>,
-    /// The message as rustc would render it.
-    rendered: Option<String>,
-}
-
-#[derive(RustcEncodable)]
-struct DiagnosticSpan {
-    file_name: String,
-    byte_start: u32,
-    byte_end: u32,
-    /// 1-based.
-    line_start: usize,
-    line_end: usize,
-    /// 1-based, character offset.
-    column_start: usize,
-    column_end: usize,
-    /// Is this a "primary" span -- meaning the point, or one of the points,
-    /// where the error occurred?
-    is_primary: bool,
-    /// Source text from the start of line_start to the end of line_end.
-    text: Vec<DiagnosticSpanLine>,
-    /// Label that should be placed at this location (if any)
-    label: Option<String>,
-    /// If we are suggesting a replacement, this will contain text
-    /// that should be sliced in atop this span.
-    suggested_replacement: Option<String>,
-    /// If the suggestion is approximate
-    suggestion_applicability: Option<Applicability>,
-    /// Macro invocations that created the code at this span, if any.
-    expansion: Option<Box<DiagnosticSpanMacroExpansion>>,
-}
-
-#[derive(RustcEncodable)]
-struct DiagnosticSpanLine {
-    text: String,
-
-    /// 1-based, character offset in self.text.
-    highlight_start: usize,
-
-    highlight_end: usize,
-}
-
-#[derive(RustcEncodable)]
-struct DiagnosticSpanMacroExpansion {
-    /// span where macro was applied to generate this code; note that
-    /// this may itself derive from a macro (if
-    /// `span.expansion.is_some()`)
-    span: DiagnosticSpan,
-
-    /// name of macro that was applied (e.g., "foo!" or "#[derive(Eq)]")
-    macro_decl_name: String,
-
-    /// span where macro was defined (if known)
-    def_site_span: DiagnosticSpan,
-}
-
-#[derive(RustcEncodable)]
-struct DiagnosticCode {
-    /// The code itself.
-    code: String,
-    /// An explanation for the code.
-    explanation: Option<&'static str>,
-}
-
-#[derive(RustcEncodable)]
-struct ArtifactNotification<'a> {
-    /// The path of the artifact.
-    artifact: &'a Path,
-    /// What kind of artifact we're emitting.
-    emit: &'a str,
-}
-
-impl Diagnostic {
-    fn from_errors_diagnostic(diag: &errors::Diagnostic,
-                               je: &JsonEmitter)
-                               -> Diagnostic {
-        let sugg = diag.suggestions.iter().map(|sugg| {
-            Diagnostic {
-                message: sugg.msg.clone(),
-                code: None,
-                level: "help",
-                spans: DiagnosticSpan::from_suggestion(sugg, je),
-                children: vec![],
-                rendered: None,
-            }
-        });
-
-        // generate regular command line output and store it in the json
-
-        // A threadsafe buffer for writing.
-        #[derive(Default, Clone)]
-        struct BufWriter(Arc<Mutex<Vec<u8>>>);
-
-        impl Write for BufWriter {
-            fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-                self.0.lock().unwrap().write(buf)
-            }
-            fn flush(&mut self) -> io::Result<()> {
-                self.0.lock().unwrap().flush()
-            }
-        }
-        let buf = BufWriter::default();
-        let output = buf.clone();
-        je.json_rendered.new_emitter(
-            Box::new(buf), Some(je.sm.clone()), false, None, je.external_macro_backtrace
-        ).ui_testing(je.ui_testing).emit_diagnostic(diag);
-        let output = Arc::try_unwrap(output.0).unwrap().into_inner().unwrap();
-        let output = String::from_utf8(output).unwrap();
-
-        Diagnostic {
-            message: diag.message(),
-            code: DiagnosticCode::map_opt_string(diag.code.clone(), je),
-            level: diag.level.to_str(),
-            spans: DiagnosticSpan::from_multispan(&diag.span, je),
-            children: diag.children.iter().map(|c| {
-                Diagnostic::from_sub_diagnostic(c, je)
-            }).chain(sugg).collect(),
-            rendered: Some(output),
-        }
-    }
-
-    fn from_sub_diagnostic(diag: &SubDiagnostic, je: &JsonEmitter) -> Diagnostic {
-        Diagnostic {
-            message: diag.message(),
-            code: None,
-            level: diag.level.to_str(),
-            spans: diag.render_span.as_ref()
-                     .map(|sp| DiagnosticSpan::from_multispan(sp, je))
-                     .unwrap_or_else(|| DiagnosticSpan::from_multispan(&diag.span, je)),
-            children: vec![],
-            rendered: None,
-        }
-    }
-}
-
-impl DiagnosticSpan {
-    fn from_span_label(span: SpanLabel,
-                       suggestion: Option<(&String, Applicability)>,
-                       je: &JsonEmitter)
-                       -> DiagnosticSpan {
-        Self::from_span_etc(span.span,
-                            span.is_primary,
-                            span.label,
-                            suggestion,
-                            je)
-    }
-
-    fn from_span_etc(span: Span,
-                     is_primary: bool,
-                     label: Option<String>,
-                     suggestion: Option<(&String, Applicability)>,
-                     je: &JsonEmitter)
-                     -> DiagnosticSpan {
-        // obtain the full backtrace from the `macro_backtrace`
-        // helper; in some ways, it'd be better to expand the
-        // backtrace ourselves, but the `macro_backtrace` helper makes
-        // some decision, such as dropping some frames, and I don't
-        // want to duplicate that logic here.
-        let backtrace = span.macro_backtrace().into_iter();
-        DiagnosticSpan::from_span_full(span,
-                                       is_primary,
-                                       label,
-                                       suggestion,
-                                       backtrace,
-                                       je)
-    }
-
-    fn from_span_full(span: Span,
-                      is_primary: bool,
-                      label: Option<String>,
-                      suggestion: Option<(&String, Applicability)>,
-                      mut backtrace: vec::IntoIter<MacroBacktrace>,
-                      je: &JsonEmitter)
-                      -> DiagnosticSpan {
-        let start = je.sm.lookup_char_pos(span.lo());
-        let end = je.sm.lookup_char_pos(span.hi());
-        let backtrace_step = backtrace.next().map(|bt| {
-            let call_site =
-                Self::from_span_full(bt.call_site,
-                                     false,
-                                     None,
-                                     None,
-                                     backtrace,
-                                     je);
-            let def_site_span =
-                Self::from_span_full(bt.def_site_span,
-                                     false,
-                                     None,
-                                     None,
-                                     vec![].into_iter(),
-                                     je);
-            Box::new(DiagnosticSpanMacroExpansion {
-                span: call_site,
-                macro_decl_name: bt.macro_decl_name,
-                def_site_span,
-            })
-        });
-
-        DiagnosticSpan {
-            file_name: start.file.name.to_string(),
-            byte_start: start.file.original_relative_byte_pos(span.lo()).0,
-            byte_end: start.file.original_relative_byte_pos(span.hi()).0,
-            line_start: start.line,
-            line_end: end.line,
-            column_start: start.col.0 + 1,
-            column_end: end.col.0 + 1,
-            is_primary,
-            text: DiagnosticSpanLine::from_span(span, je),
-            suggested_replacement: suggestion.map(|x| x.0.clone()),
-            suggestion_applicability: suggestion.map(|x| x.1),
-            expansion: backtrace_step,
-            label,
-        }
-    }
-
-    fn from_multispan(msp: &MultiSpan, je: &JsonEmitter) -> Vec<DiagnosticSpan> {
-        msp.span_labels()
-           .into_iter()
-           .map(|span_str| Self::from_span_label(span_str, None, je))
-           .collect()
-    }
-
-    fn from_suggestion(suggestion: &CodeSuggestion, je: &JsonEmitter)
-                       -> Vec<DiagnosticSpan> {
-        suggestion.substitutions
-                      .iter()
-                      .flat_map(|substitution| {
-                          substitution.parts.iter().map(move |suggestion_inner| {
-                              let span_label = SpanLabel {
-                                  span: suggestion_inner.span,
-                                  is_primary: true,
-                                  label: None,
-                              };
-                              DiagnosticSpan::from_span_label(span_label,
-                                                              Some((&suggestion_inner.snippet,
-                                                                   suggestion.applicability)),
-                                                              je)
-                          })
-                      })
-                      .collect()
-    }
-}
-
-impl DiagnosticSpanLine {
-    fn line_from_source_file(fm: &syntax_pos::SourceFile,
-                         index: usize,
-                         h_start: usize,
-                         h_end: usize)
-                         -> DiagnosticSpanLine {
-        DiagnosticSpanLine {
-            text: fm.get_line(index).map_or(String::new(), |l| l.into_owned()),
-            highlight_start: h_start,
-            highlight_end: h_end,
-        }
-    }
-
-    /// Creates a list of DiagnosticSpanLines from span - each line with any part
-    /// of `span` gets a DiagnosticSpanLine, with the highlight indicating the
-    /// `span` within the line.
-    fn from_span(span: Span, je: &JsonEmitter) -> Vec<DiagnosticSpanLine> {
-        je.sm.span_to_lines(span)
-            .map(|lines| {
-                let fm = &*lines.file;
-                lines.lines
-                    .iter()
-                    .map(|line| DiagnosticSpanLine::line_from_source_file(
-                        fm,
-                        line.line_index,
-                        line.start_col.0 + 1,
-                        line.end_col.0 + 1,
-                    )).collect()
-            }).unwrap_or_else(|_| vec![])
-    }
-}
-
-impl DiagnosticCode {
-    fn map_opt_string(s: Option<DiagnosticId>, je: &JsonEmitter) -> Option<DiagnosticCode> {
-        s.map(|s| {
-            let s = match s {
-                DiagnosticId::Error(s) => s,
-                DiagnosticId::Lint(s) => s,
-            };
-            let explanation = je.registry
-                                .as_ref()
-                                .and_then(|registry| registry.find_description(&s));
-
-            DiagnosticCode {
-                code: s,
-                explanation,
-            }
-        })
-    }
-}
diff --git a/src/libsyntax/json/tests.rs b/src/libsyntax/json/tests.rs
deleted file mode 100644
index eb0d9ef3947..00000000000
--- a/src/libsyntax/json/tests.rs
+++ /dev/null
@@ -1,186 +0,0 @@
-use super::*;
-
-use crate::json::JsonEmitter;
-use crate::source_map::{FilePathMapping, SourceMap};
-use crate::tests::Shared;
-use crate::with_default_globals;
-
-use errors::emitter::{ColorConfig, HumanReadableErrorType};
-use errors::Handler;
-use rustc_serialize::json::decode;
-use syntax_pos::{BytePos, Span};
-
-use std::str;
-
-#[derive(RustcDecodable, Debug, PartialEq, Eq)]
-struct TestData {
-    spans: Vec<SpanTestData>,
-}
-
-#[derive(RustcDecodable, Debug, PartialEq, Eq)]
-struct SpanTestData {
-    pub byte_start: u32,
-    pub byte_end: u32,
-    pub line_start: u32,
-    pub column_start: u32,
-    pub line_end: u32,
-    pub column_end: u32,
-}
-
-/// Test the span yields correct positions in JSON.
-fn test_positions(code: &str, span: (u32, u32), expected_output: SpanTestData) {
-    let expected_output = TestData { spans: vec![expected_output] };
-
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        sm.new_source_file(Path::new("test.rs").to_owned().into(), code.to_owned());
-
-        let output = Arc::new(Mutex::new(Vec::new()));
-        let je = JsonEmitter::new(
-            Box::new(Shared { data: output.clone() }),
-            None,
-            sm,
-            true,
-            HumanReadableErrorType::Short(ColorConfig::Never),
-            false,
-        );
-
-        let span = Span::with_root_ctxt(BytePos(span.0), BytePos(span.1));
-        let handler = Handler::with_emitter(true, None, Box::new(je));
-        handler.span_err(span, "foo");
-
-        let bytes = output.lock().unwrap();
-        let actual_output = str::from_utf8(&bytes).unwrap();
-        let actual_output: TestData = decode(actual_output).unwrap();
-
-        assert_eq!(expected_output, actual_output)
-    })
-}
-
-#[test]
-fn empty() {
-    test_positions(
-        " ",
-        (0, 1),
-        SpanTestData {
-            byte_start: 0,
-            byte_end: 1,
-            line_start: 1,
-            column_start: 1,
-            line_end: 1,
-            column_end: 2,
-        },
-    )
-}
-
-#[test]
-fn bom() {
-    test_positions(
-        "\u{feff} ",
-        (0, 1),
-        SpanTestData {
-            byte_start: 3,
-            byte_end: 4,
-            line_start: 1,
-            column_start: 1,
-            line_end: 1,
-            column_end: 2,
-        },
-    )
-}
-
-#[test]
-fn lf_newlines() {
-    test_positions(
-        "\nmod foo;\nmod bar;\n",
-        (5, 12),
-        SpanTestData {
-            byte_start: 5,
-            byte_end: 12,
-            line_start: 2,
-            column_start: 5,
-            line_end: 3,
-            column_end: 3,
-        },
-    )
-}
-
-#[test]
-fn crlf_newlines() {
-    test_positions(
-        "\r\nmod foo;\r\nmod bar;\r\n",
-        (5, 12),
-        SpanTestData {
-            byte_start: 6,
-            byte_end: 14,
-            line_start: 2,
-            column_start: 5,
-            line_end: 3,
-            column_end: 3,
-        },
-    )
-}
-
-#[test]
-fn crlf_newlines_with_bom() {
-    test_positions(
-        "\u{feff}\r\nmod foo;\r\nmod bar;\r\n",
-        (5, 12),
-        SpanTestData {
-            byte_start: 9,
-            byte_end: 17,
-            line_start: 2,
-            column_start: 5,
-            line_end: 3,
-            column_end: 3,
-        },
-    )
-}
-
-#[test]
-fn span_before_crlf() {
-    test_positions(
-        "foo\r\nbar",
-        (2, 3),
-        SpanTestData {
-            byte_start: 2,
-            byte_end: 3,
-            line_start: 1,
-            column_start: 3,
-            line_end: 1,
-            column_end: 4,
-        },
-    )
-}
-
-#[test]
-fn span_on_crlf() {
-    test_positions(
-        "foo\r\nbar",
-        (3, 4),
-        SpanTestData {
-            byte_start: 3,
-            byte_end: 5,
-            line_start: 1,
-            column_start: 4,
-            line_end: 2,
-            column_end: 1,
-        },
-    )
-}
-
-#[test]
-fn span_after_crlf() {
-    test_positions(
-        "foo\r\nbar",
-        (4, 5),
-        SpanTestData {
-            byte_start: 5,
-            byte_end: 6,
-            line_start: 2,
-            column_start: 1,
-            line_end: 2,
-            column_end: 2,
-        },
-    )
-}
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 1b17de529c4..36173801eae 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -7,11 +7,13 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/",
        test(attr(deny(warnings))))]
 
+#![feature(bool_to_option)]
 #![feature(box_syntax)]
 #![feature(const_fn)]
 #![feature(const_transmute)]
 #![feature(crate_visibility_modifier)]
 #![feature(label_break_value)]
+#![feature(matches_macro)]
 #![feature(nll)]
 #![feature(try_trait)]
 #![feature(slice_patterns)]
@@ -26,11 +28,6 @@ pub use rustc_data_structures::thin_vec::ThinVec;
 use ast::AttrId;
 use syntax_pos::edition::Edition;
 
-#[cfg(test)]
-mod tests;
-
-pub const MACRO_ARGUMENTS: Option<&'static str> = Some("macro arguments");
-
 #[macro_export]
 macro_rules! unwrap_or {
     ($opt:expr, $default:expr) => {
@@ -82,34 +79,31 @@ pub mod diagnostics {
     pub mod macros;
 }
 
-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;
 }
 
-pub mod json;
-
 pub mod ast;
 pub mod attr;
 pub mod expand;
-pub mod source_map;
-#[macro_use] pub mod config;
+pub use syntax_pos::source_map;
 pub mod entry;
-pub mod feature_gate;
+pub mod feature_gate {
+    mod check;
+    pub use check::{check_crate, check_attribute, get_features, feature_err, feature_err_issue};
+}
 pub mod mut_visit;
-pub mod parse;
 pub mod ptr;
 pub mod show_span;
 pub use syntax_pos::edition;
 pub use syntax_pos::symbol;
-pub mod sess;
+pub use rustc_session::parse as sess;
 pub mod token;
 pub mod tokenstream;
 pub mod visit;
@@ -121,3 +115,8 @@ pub mod print {
 }
 
 pub mod early_buffered_lints;
+
+/// Requirements for a `StableHashingContext` to be used in this crate.
+/// This is a hack to allow using the `HashStable_Generic` derive macro
+/// instead of implementing everything in librustc.
+pub trait HashStableContext: syntax_pos::HashStableContext {}
diff --git a/src/libsyntax/mut_visit.rs b/src/libsyntax/mut_visit.rs
index 7696ea48f93..f8795d885d2 100644
--- a/src/libsyntax/mut_visit.rs
+++ b/src/libsyntax/mut_visit.rs
@@ -22,9 +22,6 @@ use rustc_data_structures::sync::Lrc;
 use std::ops::DerefMut;
 use std::{panic, process, ptr};
 
-#[cfg(test)]
-mod tests;
-
 pub trait ExpectOne<A: Array> {
     fn expect_one(self, err: &'static str) -> A::Item;
 }
@@ -362,6 +359,26 @@ pub fn visit_fn_sig<T: MutVisitor>(FnSig { header, decl }: &mut FnSig, vis: &mut
     vis.visit_fn_decl(decl);
 }
 
+// No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
+pub fn visit_mac_args<T: MutVisitor>(args: &mut MacArgs, vis: &mut T) {
+    match args {
+        MacArgs::Empty => {}
+        MacArgs::Delimited(dspan, _delim, tokens) => {
+            visit_delim_span(dspan, vis);
+            vis.visit_tts(tokens);
+        }
+        MacArgs::Eq(eq_span, tokens) => {
+            vis.visit_span(eq_span);
+            vis.visit_tts(tokens);
+        }
+    }
+}
+
+pub fn visit_delim_span<T: MutVisitor>(dspan: &mut DelimSpan, vis: &mut T) {
+    vis.visit_span(&mut dspan.open);
+    vis.visit_span(&mut dspan.close);
+}
+
 pub fn noop_flat_map_field_pattern<T: MutVisitor>(
     mut fp: FieldPat,
     vis: &mut T,
@@ -444,7 +461,7 @@ pub fn noop_visit_ty<T: MutVisitor>(ty: &mut P<Ty>, vis: &mut T) {
             vis.visit_mt(mt);
         }
         TyKind::BareFn(bft) => {
-            let BareFnTy { unsafety: _, abi: _, generic_params, decl } = bft.deref_mut();
+            let BareFnTy { unsafety: _, ext: _, generic_params, decl } = bft.deref_mut();
             generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
             vis.visit_fn_decl(decl);
         }
@@ -475,16 +492,17 @@ pub fn noop_visit_foreign_mod<T: MutVisitor>(foreign_mod: &mut ForeignMod, vis:
     items.flat_map_in_place(|item| vis.flat_map_foreign_item(item));
 }
 
-pub fn noop_flat_map_variant<T: MutVisitor>(mut variant: Variant, vis: &mut T)
+pub fn noop_flat_map_variant<T: MutVisitor>(mut variant: Variant, visitor: &mut T)
     -> SmallVec<[Variant; 1]>
 {
-    let Variant { ident, attrs, id, data, disr_expr, span, is_placeholder: _ } = &mut variant;
-    vis.visit_ident(ident);
-    visit_attrs(attrs, vis);
-    vis.visit_id(id);
-    vis.visit_variant_data(data);
-    visit_opt(disr_expr, |disr_expr| vis.visit_anon_const(disr_expr));
-    vis.visit_span(span);
+    let Variant { ident, vis, attrs, id, data, disr_expr, span, is_placeholder: _ } = &mut variant;
+    visitor.visit_ident(ident);
+    visitor.visit_vis(vis);
+    visit_attrs(attrs, visitor);
+    visitor.visit_id(id);
+    visitor.visit_variant_data(data);
+    visit_opt(disr_expr, |disr_expr| visitor.visit_anon_const(disr_expr));
+    visitor.visit_span(span);
     smallvec![variant]
 }
 
@@ -552,9 +570,9 @@ 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 { kind, id: _, style: _, span } = attr;
     match kind {
-        AttrKind::Normal(AttrItem { path, tokens }) => {
+        AttrKind::Normal(AttrItem { path, args }) => {
             vis.visit_path(path);
-            vis.visit_tts(tokens);
+            visit_mac_args(args, vis);
         }
         AttrKind::DocComment(_) => {}
     }
@@ -562,15 +580,14 @@ pub fn noop_visit_attribute<T: MutVisitor>(attr: &mut Attribute, vis: &mut T) {
 }
 
 pub fn noop_visit_mac<T: MutVisitor>(mac: &mut Mac, vis: &mut T) {
-    let Mac { path, delim: _, tts, span, prior_type_ascription: _ } = mac;
+    let Mac { path, args, prior_type_ascription: _ } = mac;
     vis.visit_path(path);
-    vis.visit_tts(tts);
-    vis.visit_span(span);
+    visit_mac_args(args, vis);
 }
 
 pub fn noop_visit_macro_def<T: MutVisitor>(macro_def: &mut MacroDef, vis: &mut T) {
-    let MacroDef { tokens, legacy: _ } = macro_def;
-    vis.visit_tts(tokens);
+    let MacroDef { body, legacy: _ } = macro_def;
+    visit_mac_args(body, vis);
 }
 
 pub fn noop_visit_meta_list_item<T: MutVisitor>(li: &mut NestedMetaItem, vis: &mut T) {
@@ -684,9 +701,9 @@ pub fn noop_visit_interpolated<T: MutVisitor>(nt: &mut token::Nonterminal, vis:
         token::NtIdent(ident, _is_raw) => vis.visit_ident(ident),
         token::NtLifetime(ident) => vis.visit_ident(ident),
         token::NtLiteral(expr) => vis.visit_expr(expr),
-        token::NtMeta(AttrItem { path, tokens }) => {
+        token::NtMeta(AttrItem { path, args }) => {
             vis.visit_path(path);
-            vis.visit_tts(tokens);
+            visit_mac_args(args, vis);
         }
         token::NtPath(path) => vis.visit_path(path),
         token::NtTT(tt) => vis.visit_tt(tt),
@@ -890,10 +907,6 @@ pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
             vis.visit_ty(ty);
             vis.visit_generics(generics);
         }
-        ItemKind::OpaqueTy(bounds, generics) => {
-            visit_bounds(bounds, vis);
-            vis.visit_generics(generics);
-        }
         ItemKind::Enum(EnumDef { variants }, generics) => {
             variants.flat_map_in_place(|variant| vis.flat_map_variant(variant));
             vis.visit_generics(generics);
@@ -923,32 +936,33 @@ pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
     }
 }
 
-pub fn noop_flat_map_trait_item<T: MutVisitor>(mut item: TraitItem, vis: &mut T)
+pub fn noop_flat_map_trait_item<T: MutVisitor>(mut item: TraitItem, visitor: &mut T)
     -> SmallVec<[TraitItem; 1]>
 {
-    let TraitItem { id, ident, attrs, generics, kind, span, tokens: _ } = &mut item;
-    vis.visit_id(id);
-    vis.visit_ident(ident);
-    visit_attrs(attrs, vis);
-    vis.visit_generics(generics);
+    let TraitItem { id, ident, vis, attrs, generics, kind, span, tokens: _ } = &mut item;
+    visitor.visit_id(id);
+    visitor.visit_ident(ident);
+    visitor.visit_vis(vis);
+    visit_attrs(attrs, visitor);
+    visitor.visit_generics(generics);
     match kind {
         TraitItemKind::Const(ty, default) => {
-            vis.visit_ty(ty);
-            visit_opt(default, |default| vis.visit_expr(default));
+            visitor.visit_ty(ty);
+            visit_opt(default, |default| visitor.visit_expr(default));
         }
         TraitItemKind::Method(sig, body) => {
-            visit_fn_sig(sig, vis);
-            visit_opt(body, |body| vis.visit_block(body));
+            visit_fn_sig(sig, visitor);
+            visit_opt(body, |body| visitor.visit_block(body));
         }
         TraitItemKind::Type(bounds, default) => {
-            visit_bounds(bounds, vis);
-            visit_opt(default, |default| vis.visit_ty(default));
+            visit_bounds(bounds, visitor);
+            visit_opt(default, |default| visitor.visit_ty(default));
         }
         TraitItemKind::Macro(mac) => {
-            vis.visit_mac(mac);
+            visitor.visit_mac(mac);
         }
     }
-    vis.visit_span(span);
+    visitor.visit_span(span);
 
     smallvec![item]
 }
@@ -973,7 +987,6 @@ pub fn noop_flat_map_impl_item<T: MutVisitor>(mut item: ImplItem, visitor: &mut
             visitor.visit_block(body);
         }
         ImplItemKind::TyAlias(ty) => visitor.visit_ty(ty),
-        ImplItemKind::OpaqueTy(bounds) => visit_bounds(bounds, visitor),
         ImplItemKind::Macro(mac) => visitor.visit_mac(mac),
     }
     visitor.visit_span(span);
@@ -982,7 +995,7 @@ pub fn noop_flat_map_impl_item<T: MutVisitor>(mut item: ImplItem, visitor: &mut
 }
 
 pub fn noop_visit_fn_header<T: MutVisitor>(header: &mut FnHeader, vis: &mut T) {
-    let FnHeader { unsafety: _, asyncness, constness: _, abi: _ } = header;
+    let FnHeader { unsafety: _, asyncness, constness: _, ext: _ } = header;
     vis.visit_asyncness(&mut asyncness.node);
 }
 
@@ -1040,7 +1053,7 @@ pub fn noop_flat_map_item<T: MutVisitor>(mut item: P<Item>, visitor: &mut T)
 pub fn noop_flat_map_foreign_item<T: MutVisitor>(mut item: ForeignItem, visitor: &mut T)
     -> SmallVec<[ForeignItem; 1]>
 {
-    let ForeignItem { ident, attrs, kind, id, span, vis } = &mut item;
+    let ForeignItem { ident, attrs, id, kind, vis, span, tokens: _ } = &mut item;
     visitor.visit_ident(ident);
     visit_attrs(attrs, visitor);
     match kind {
@@ -1134,7 +1147,7 @@ pub fn noop_visit_expr<T: MutVisitor>(Expr { kind, id, span, attrs }: &mut Expr,
             vis.visit_expr(expr);
             vis.visit_ty(ty);
         }
-        ExprKind::AddrOf(_m, ohs) => vis.visit_expr(ohs),
+        ExprKind::AddrOf(_, _, ohs) => vis.visit_expr(ohs),
         ExprKind::Let(pat, scrutinee) => {
             vis.visit_pat(pat);
             vis.visit_expr(scrutinee);
diff --git a/src/libsyntax/mut_visit/tests.rs b/src/libsyntax/mut_visit/tests.rs
deleted file mode 100644
index f779e0d0a60..00000000000
--- a/src/libsyntax/mut_visit/tests.rs
+++ /dev/null
@@ -1,71 +0,0 @@
-use super::*;
-
-use crate::ast::{self, Ident};
-use crate::tests::{string_to_crate, matches_codepattern};
-use crate::print::pprust;
-use crate::mut_visit;
-use crate::with_default_globals;
-
-// This version doesn't care about getting comments or doc-strings in.
-fn fake_print_crate(s: &mut pprust::State<'_>,
-                    krate: &ast::Crate) {
-    s.print_mod(&krate.module, &krate.attrs)
-}
-
-// Change every identifier to "zz".
-struct ToZzIdentMutVisitor;
-
-impl MutVisitor for ToZzIdentMutVisitor {
-    fn visit_ident(&mut self, ident: &mut ast::Ident) {
-        *ident = Ident::from_str("zz");
-    }
-    fn visit_mac(&mut self, mac: &mut ast::Mac) {
-        mut_visit::noop_visit_mac(mac, self)
-    }
-}
-
-// Maybe add to `expand.rs`.
-macro_rules! assert_pred {
-    ($pred:expr, $predname:expr, $a:expr , $b:expr) => (
-        {
-            let pred_val = $pred;
-            let a_val = $a;
-            let b_val = $b;
-            if !(pred_val(&a_val, &b_val)) {
-                panic!("expected args satisfying {}, got {} and {}",
-                        $predname, a_val, b_val);
-            }
-        }
-    )
-}
-
-// Make sure idents get transformed everywhere.
-#[test] fn ident_transformation () {
-    with_default_globals(|| {
-        let mut zz_visitor = ToZzIdentMutVisitor;
-        let mut krate = string_to_crate(
-            "#[a] mod b {fn c (d : e, f : g) {h!(i,j,k);l;m}}".to_string());
-        zz_visitor.visit_crate(&mut krate);
-        assert_pred!(
-            matches_codepattern,
-            "matches_codepattern",
-            pprust::to_string(|s| fake_print_crate(s, &krate)),
-            "#[zz]mod zz{fn zz(zz:zz,zz:zz){zz!(zz,zz,zz);zz;zz}}".to_string());
-    })
-}
-
-// Make sure idents get transformed even inside macro defs.
-#[test] fn ident_transformation_in_defs () {
-    with_default_globals(|| {
-        let mut zz_visitor = ToZzIdentMutVisitor;
-        let mut krate = string_to_crate(
-            "macro_rules! a {(b $c:expr $(d $e:token)f+ => \
-            (g $(d $d $e)+))} ".to_string());
-        zz_visitor.visit_crate(&mut krate);
-        assert_pred!(
-            matches_codepattern,
-            "matches_codepattern",
-            pprust::to_string(|s| fake_print_crate(s, &krate)),
-            "macro_rules! zz{(zz$zz:zz$(zz $zz:zz)zz+=>(zz$(zz$zz$zz)+))}".to_string());
-    })
-}
diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
deleted file mode 100644
index b1b7b08c78a..00000000000
--- a/src/libsyntax/parse/lexer/mod.rs
+++ /dev/null
@@ -1,645 +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;
-
-#[cfg(test)]
-mod tests;
-
-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.
-    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/tests.rs b/src/libsyntax/parse/lexer/tests.rs
deleted file mode 100644
index baa6fb59537..00000000000
--- a/src/libsyntax/parse/lexer/tests.rs
+++ /dev/null
@@ -1,270 +0,0 @@
-use super::*;
-
-use crate::symbol::Symbol;
-use crate::source_map::{SourceMap, FilePathMapping};
-use crate::token;
-use crate::util::comments::is_doc_comment;
-use crate::with_default_globals;
-
-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(
-        Box::new(io::sink()),
-        Some(sm.clone()),
-        false,
-        false,
-        false,
-        None,
-        false,
-    );
-    ParseSess::with_span_handler(Handler::with_emitter(true, None, Box::new(emitter)), sm)
-}
-
-// Creates a string reader for the given string.
-fn setup<'a>(sm: &SourceMap,
-                sess: &'a ParseSess,
-                teststr: String)
-                -> StringReader<'a> {
-    let sf = sm.new_source_file(PathBuf::from(teststr.clone()).into(), teststr);
-    StringReader::new(sess, sf, None)
-}
-
-#[test]
-fn t1() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        let mut string_reader = setup(
-            &sm,
-            &sh,
-            "/* my source file */ fn main() { println!(\"zebra\"); }\n".to_string(),
-        );
-        assert_eq!(string_reader.next_token(), token::Comment);
-        assert_eq!(string_reader.next_token(), token::Whitespace);
-        let tok1 = string_reader.next_token();
-        let tok2 = Token::new(
-            mk_ident("fn"),
-            Span::with_root_ctxt(BytePos(21), BytePos(23)),
-        );
-        assert_eq!(tok1.kind, tok2.kind);
-        assert_eq!(tok1.span, tok2.span);
-        assert_eq!(string_reader.next_token(), token::Whitespace);
-        // Read another token.
-        let tok3 = string_reader.next_token();
-        assert_eq!(string_reader.pos.clone(), BytePos(28));
-        let tok4 = Token::new(
-            mk_ident("main"),
-            Span::with_root_ctxt(BytePos(24), BytePos(28)),
-        );
-        assert_eq!(tok3.kind, tok4.kind);
-        assert_eq!(tok3.span, tok4.span);
-
-        assert_eq!(string_reader.next_token(), token::OpenDelim(token::Paren));
-        assert_eq!(string_reader.pos.clone(), BytePos(29))
-    })
-}
-
-// Checks that the given reader produces the desired stream
-// of tokens (stop checking after exhausting `expected`).
-fn check_tokenization(mut string_reader: StringReader<'_>, expected: Vec<TokenKind>) {
-    for expected_tok in &expected {
-        assert_eq!(&string_reader.next_token(), expected_tok);
-    }
-}
-
-// Makes the identifier by looking up the string in the interner.
-fn mk_ident(id: &str) -> TokenKind {
-    token::Ident(Symbol::intern(id), false)
-}
-
-fn mk_lit(kind: token::LitKind, symbol: &str, suffix: Option<&str>) -> TokenKind {
-    TokenKind::lit(kind, Symbol::intern(symbol), suffix.map(Symbol::intern))
-}
-
-#[test]
-fn doublecolon_parsing() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        check_tokenization(
-            setup(&sm, &sh, "a b".to_string()),
-            vec![mk_ident("a"), token::Whitespace, mk_ident("b")],
-        );
-    })
-}
-
-#[test]
-fn doublecolon_parsing_2() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        check_tokenization(
-            setup(&sm, &sh, "a::b".to_string()),
-            vec![mk_ident("a"), token::Colon, token::Colon, mk_ident("b")],
-        );
-    })
-}
-
-#[test]
-fn doublecolon_parsing_3() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        check_tokenization(
-            setup(&sm, &sh, "a ::b".to_string()),
-            vec![mk_ident("a"), token::Whitespace, token::Colon, token::Colon, mk_ident("b")],
-        );
-    })
-}
-
-#[test]
-fn doublecolon_parsing_4() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        check_tokenization(
-            setup(&sm, &sh, "a:: b".to_string()),
-            vec![mk_ident("a"), token::Colon, token::Colon, token::Whitespace, mk_ident("b")],
-        );
-    })
-}
-
-#[test]
-fn character_a() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        assert_eq!(
-            setup(&sm, &sh, "'a'".to_string()).next_token(),
-            mk_lit(token::Char, "a", None),
-        );
-    })
-}
-
-#[test]
-fn character_space() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        assert_eq!(
-            setup(&sm, &sh, "' '".to_string()).next_token(),
-            mk_lit(token::Char, " ", None),
-        );
-    })
-}
-
-#[test]
-fn character_escaped() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        assert_eq!(
-            setup(&sm, &sh, "'\\n'".to_string()).next_token(),
-            mk_lit(token::Char, "\\n", None),
-        );
-    })
-}
-
-#[test]
-fn lifetime_name() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        assert_eq!(
-            setup(&sm, &sh, "'abc".to_string()).next_token(),
-            token::Lifetime(Symbol::intern("'abc")),
-        );
-    })
-}
-
-#[test]
-fn raw_string() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        assert_eq!(
-            setup(&sm, &sh, "r###\"\"#a\\b\x00c\"\"###".to_string()).next_token(),
-            mk_lit(token::StrRaw(3), "\"#a\\b\x00c\"", None),
-        );
-    })
-}
-
-#[test]
-fn literal_suffixes() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        macro_rules! test {
-            ($input: expr, $tok_type: ident, $tok_contents: expr) => {{
-                assert_eq!(
-                    setup(&sm, &sh, format!("{}suffix", $input)).next_token(),
-                    mk_lit(token::$tok_type, $tok_contents, Some("suffix")),
-                );
-                // with a whitespace separator
-                assert_eq!(
-                    setup(&sm, &sh, format!("{} suffix", $input)).next_token(),
-                    mk_lit(token::$tok_type, $tok_contents, None),
-                );
-            }}
-        }
-
-        test!("'a'", Char, "a");
-        test!("b'a'", Byte, "a");
-        test!("\"a\"", Str, "a");
-        test!("b\"a\"", ByteStr, "a");
-        test!("1234", Integer, "1234");
-        test!("0b101", Integer, "0b101");
-        test!("0xABC", Integer, "0xABC");
-        test!("1.0", Float, "1.0");
-        test!("1.0e10", Float, "1.0e10");
-
-        assert_eq!(
-            setup(&sm, &sh, "2us".to_string()).next_token(),
-            mk_lit(token::Integer, "2", Some("us")),
-        );
-        assert_eq!(
-            setup(&sm, &sh, "r###\"raw\"###suffix".to_string()).next_token(),
-            mk_lit(token::StrRaw(3), "raw", Some("suffix")),
-        );
-        assert_eq!(
-            setup(&sm, &sh, "br###\"raw\"###suffix".to_string()).next_token(),
-            mk_lit(token::ByteStrRaw(3), "raw", Some("suffix")),
-        );
-    })
-}
-
-#[test]
-fn line_doc_comments() {
-    assert!(is_doc_comment("///"));
-    assert!(is_doc_comment("/// blah"));
-    assert!(!is_doc_comment("////"));
-}
-
-#[test]
-fn nested_block_comments() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        let mut lexer = setup(&sm, &sh, "/* /* */ */'a'".to_string());
-        assert_eq!(lexer.next_token(), token::Comment);
-        assert_eq!(lexer.next_token(), mk_lit(token::Char, "a", None));
-    })
-}
-
-#[test]
-fn crlf_comments() {
-    with_default_globals(|| {
-        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let sh = mk_sess(sm.clone());
-        let mut lexer = setup(&sm, &sh, "// test\r\n/// test\r\n".to_string());
-        let comment = lexer.next_token();
-        assert_eq!(comment.kind, token::Comment);
-        assert_eq!((comment.span.lo(), comment.span.hi()), (BytePos(0), BytePos(7)));
-        assert_eq!(lexer.next_token(), token::Whitespace);
-        assert_eq!(lexer.next_token(), token::DocComment(Symbol::intern("/// test")));
-    })
-}
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 b54f4862f12..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;
-
-#[cfg(test)]
-mod tests;
-
-#[macro_use]
-pub mod parser;
-pub mod lexer;
-
-#[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 31f0a02a483..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.
-    crate 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 3e5974c2eee..00000000000
--- a/src/libsyntax/parse/parser/module.rs
+++ /dev/null
@@ -1,320 +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 crate::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> {
-        let (in_cfg, outer_attrs) = {
-            // FIXME(Centril): This results in a cycle between config and parsing.
-            // Consider using dynamic dispatch via `self.sess` to disentangle the knot.
-            let mut strip_unconfigured = crate::config::StripUnconfigured {
-                sess: self.sess,
-                features: None, // Don't perform gated feature checking.
-            };
-            let mut outer_attrs = outer_attrs.to_owned();
-            strip_unconfigured.process_cfg_attrs(&mut outer_attrs);
-            (!self.cfg_mods || strip_unconfigured.in_cfg(&outer_attrs), 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/tests.rs b/src/libsyntax/parse/tests.rs
deleted file mode 100644
index 27ca2b6472f..00000000000
--- a/src/libsyntax/parse/tests.rs
+++ /dev/null
@@ -1,339 +0,0 @@
-use super::*;
-
-use crate::ast::{self, Name, PatKind};
-use crate::attr::first_attr_value_str_by_name;
-use crate::sess::ParseSess;
-use crate::parse::{PResult, new_parser_from_source_str};
-use crate::token::Token;
-use crate::print::pprust::item_to_string;
-use crate::ptr::P;
-use crate::source_map::FilePathMapping;
-use crate::symbol::{kw, sym};
-use crate::tests::{matches_codepattern, string_to_stream, with_error_checking_parse};
-use crate::tokenstream::{DelimSpan, TokenTree, TokenStream};
-use crate::with_default_globals;
-use syntax_pos::{Span, BytePos, Pos};
-
-use std::path::PathBuf;
-
-/// Parses an item.
-///
-/// Returns `Ok(Some(item))` when successful, `Ok(None)` when no item was found, and `Err`
-/// when a syntax error occurred.
-fn parse_item_from_source_str(name: FileName, source: String, sess: &ParseSess)
-                                    -> PResult<'_, Option<P<ast::Item>>> {
-    new_parser_from_source_str(sess, name, source).parse_item()
-}
-
-// Produces a `syntax_pos::span`.
-fn sp(a: u32, b: u32) -> Span {
-    Span::with_root_ctxt(BytePos(a), BytePos(b))
-}
-
-/// Parses a string, return an expression.
-fn string_to_expr(source_str : String) -> P<ast::Expr> {
-    let ps = ParseSess::new(FilePathMapping::empty());
-    with_error_checking_parse(source_str, &ps, |p| {
-        p.parse_expr()
-    })
-}
-
-/// Parses a string, returns an item.
-fn string_to_item(source_str : String) -> Option<P<ast::Item>> {
-    let ps = ParseSess::new(FilePathMapping::empty());
-    with_error_checking_parse(source_str, &ps, |p| {
-        p.parse_item()
-    })
-}
-
-#[should_panic]
-#[test] fn bad_path_expr_1() {
-    with_default_globals(|| {
-        string_to_expr("::abc::def::return".to_string());
-    })
-}
-
-// Checks the token-tree-ization of macros.
-#[test]
-fn string_to_tts_macro () {
-    with_default_globals(|| {
-        let tts: Vec<_> =
-            string_to_stream("macro_rules! zip (($a)=>($a))".to_string()).trees().collect();
-        let tts: &[TokenTree] = &tts[..];
-
-        match tts {
-            [
-                TokenTree::Token(Token { kind: token::Ident(name_macro_rules, false), .. }),
-                TokenTree::Token(Token { kind: token::Not, .. }),
-                TokenTree::Token(Token { kind: token::Ident(name_zip, false), .. }),
-                TokenTree::Delimited(_, macro_delim,  macro_tts)
-            ]
-            if name_macro_rules == &sym::macro_rules && name_zip.as_str() == "zip" => {
-                let tts = &macro_tts.trees().collect::<Vec<_>>();
-                match &tts[..] {
-                    [
-                        TokenTree::Delimited(_, first_delim, first_tts),
-                        TokenTree::Token(Token { kind: token::FatArrow, .. }),
-                        TokenTree::Delimited(_, second_delim, second_tts),
-                    ]
-                    if macro_delim == &token::Paren => {
-                        let tts = &first_tts.trees().collect::<Vec<_>>();
-                        match &tts[..] {
-                            [
-                                TokenTree::Token(Token { kind: token::Dollar, .. }),
-                                TokenTree::Token(Token { kind: token::Ident(name, false), .. }),
-                            ]
-                            if first_delim == &token::Paren && name.as_str() == "a" => {},
-                            _ => panic!("value 3: {:?} {:?}", first_delim, first_tts),
-                        }
-                        let tts = &second_tts.trees().collect::<Vec<_>>();
-                        match &tts[..] {
-                            [
-                                TokenTree::Token(Token { kind: token::Dollar, .. }),
-                                TokenTree::Token(Token { kind: token::Ident(name, false), .. }),
-                            ]
-                            if second_delim == &token::Paren && name.as_str() == "a" => {},
-                            _ => panic!("value 4: {:?} {:?}", second_delim, second_tts),
-                        }
-                    },
-                    _ => panic!("value 2: {:?} {:?}", macro_delim, macro_tts),
-                }
-            },
-            _ => panic!("value: {:?}",tts),
-        }
-    })
-}
-
-#[test]
-fn string_to_tts_1() {
-    with_default_globals(|| {
-        let tts = string_to_stream("fn a (b : i32) { b; }".to_string());
-
-        let expected = TokenStream::new(vec![
-            TokenTree::token(token::Ident(kw::Fn, false), sp(0, 2)).into(),
-            TokenTree::token(token::Ident(Name::intern("a"), false), sp(3, 4)).into(),
-            TokenTree::Delimited(
-                DelimSpan::from_pair(sp(5, 6), sp(13, 14)),
-                token::DelimToken::Paren,
-                TokenStream::new(vec![
-                    TokenTree::token(token::Ident(Name::intern("b"), false), sp(6, 7)).into(),
-                    TokenTree::token(token::Colon, sp(8, 9)).into(),
-                    TokenTree::token(token::Ident(sym::i32, false), sp(10, 13)).into(),
-                ]).into(),
-            ).into(),
-            TokenTree::Delimited(
-                DelimSpan::from_pair(sp(15, 16), sp(20, 21)),
-                token::DelimToken::Brace,
-                TokenStream::new(vec![
-                    TokenTree::token(token::Ident(Name::intern("b"), false), sp(17, 18)).into(),
-                    TokenTree::token(token::Semi, sp(18, 19)).into(),
-                ]).into(),
-            ).into()
-        ]);
-
-        assert_eq!(tts, expected);
-    })
-}
-
-#[test] fn parse_use() {
-    with_default_globals(|| {
-        let use_s = "use foo::bar::baz;";
-        let vitem = string_to_item(use_s.to_string()).unwrap();
-        let vitem_s = item_to_string(&vitem);
-        assert_eq!(&vitem_s[..], use_s);
-
-        let use_s = "use foo::bar as baz;";
-        let vitem = string_to_item(use_s.to_string()).unwrap();
-        let vitem_s = item_to_string(&vitem);
-        assert_eq!(&vitem_s[..], use_s);
-    })
-}
-
-#[test] fn parse_extern_crate() {
-    with_default_globals(|| {
-        let ex_s = "extern crate foo;";
-        let vitem = string_to_item(ex_s.to_string()).unwrap();
-        let vitem_s = item_to_string(&vitem);
-        assert_eq!(&vitem_s[..], ex_s);
-
-        let ex_s = "extern crate foo as bar;";
-        let vitem = string_to_item(ex_s.to_string()).unwrap();
-        let vitem_s = item_to_string(&vitem);
-        assert_eq!(&vitem_s[..], ex_s);
-    })
-}
-
-fn get_spans_of_pat_idents(src: &str) -> Vec<Span> {
-    let item = string_to_item(src.to_string()).unwrap();
-
-    struct PatIdentVisitor {
-        spans: Vec<Span>
-    }
-    impl<'a> crate::visit::Visitor<'a> for PatIdentVisitor {
-        fn visit_pat(&mut self, p: &'a ast::Pat) {
-            match p.kind {
-                PatKind::Ident(_ , ref ident, _) => {
-                    self.spans.push(ident.span.clone());
-                }
-                _ => {
-                    crate::visit::walk_pat(self, p);
-                }
-            }
-        }
-    }
-    let mut v = PatIdentVisitor { spans: Vec::new() };
-    crate::visit::walk_item(&mut v, &item);
-    return v.spans;
-}
-
-#[test] fn span_of_self_arg_pat_idents_are_correct() {
-    with_default_globals(|| {
-
-        let srcs = ["impl z { fn a (&self, &myarg: i32) {} }",
-                    "impl z { fn a (&mut self, &myarg: i32) {} }",
-                    "impl z { fn a (&'a self, &myarg: i32) {} }",
-                    "impl z { fn a (self, &myarg: i32) {} }",
-                    "impl z { fn a (self: Foo, &myarg: i32) {} }",
-                    ];
-
-        for &src in &srcs {
-            let spans = get_spans_of_pat_idents(src);
-            let (lo, hi) = (spans[0].lo(), spans[0].hi());
-            assert!("self" == &src[lo.to_usize()..hi.to_usize()],
-                    "\"{}\" != \"self\". src=\"{}\"",
-                    &src[lo.to_usize()..hi.to_usize()], src)
-        }
-    })
-}
-
-#[test] fn parse_exprs () {
-    with_default_globals(|| {
-        // just make sure that they parse....
-        string_to_expr("3 + 4".to_string());
-        string_to_expr("a::z.froob(b,&(987+3))".to_string());
-    })
-}
-
-#[test] fn attrs_fix_bug () {
-    with_default_globals(|| {
-        string_to_item("pub fn mk_file_writer(path: &Path, flags: &[FileFlag])
-                -> Result<Box<Writer>, String> {
-#[cfg(windows)]
-fn wb() -> c_int {
-    (O_WRONLY | libc::consts::os::extra::O_BINARY) as c_int
-}
-
-#[cfg(unix)]
-fn wb() -> c_int { O_WRONLY as c_int }
-
-let mut fflags: c_int = wb();
-}".to_string());
-    })
-}
-
-#[test] fn crlf_doc_comments() {
-    with_default_globals(|| {
-        let sess = ParseSess::new(FilePathMapping::empty());
-
-        let name_1 = FileName::Custom("crlf_source_1".to_string());
-        let source = "/// doc comment\r\nfn foo() {}".to_string();
-        let item = parse_item_from_source_str(name_1, source, &sess)
-            .unwrap().unwrap();
-        let doc = first_attr_value_str_by_name(&item.attrs, sym::doc).unwrap();
-        assert_eq!(doc.as_str(), "/// doc comment");
-
-        let name_2 = FileName::Custom("crlf_source_2".to_string());
-        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.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);
-
-        let name_3 = FileName::Custom("clrf_source_3".to_string());
-        let source = "/** doc comment\r\n *  with CRLF */\r\nfn foo() {}".to_string();
-        let item = parse_item_from_source_str(name_3, source, &sess).unwrap().unwrap();
-        let doc = first_attr_value_str_by_name(&item.attrs, sym::doc).unwrap();
-        assert_eq!(doc.as_str(), "/** doc comment\n *  with CRLF */");
-    });
-}
-
-#[test]
-fn ttdelim_span() {
-    fn parse_expr_from_source_str(
-        name: FileName, source: String, sess: &ParseSess
-    ) -> PResult<'_, P<ast::Expr>> {
-        new_parser_from_source_str(sess, name, source).parse_expr()
-    }
-
-    with_default_globals(|| {
-        let sess = ParseSess::new(FilePathMapping::empty());
-        let expr = parse_expr_from_source_str(PathBuf::from("foo").into(),
-            "foo!( fn main() { body } )".to_string(), &sess).unwrap();
-
-        let tts: Vec<_> = match expr.kind {
-            ast::ExprKind::Mac(ref mac) => mac.stream().trees().collect(),
-            _ => panic!("not a macro"),
-        };
-
-        let span = tts.iter().rev().next().unwrap().span();
-
-        match sess.source_map().span_to_snippet(span) {
-            Ok(s) => assert_eq!(&s[..], "{ body }"),
-            Err(_) => panic!("could not get snippet"),
-        }
-    });
-}
-
-// This tests that when parsing a string (rather than a file) we don't try
-// and read in a file for a module declaration and just parse a stub.
-// See `recurse_into_file_modules` in the parser.
-#[test]
-fn out_of_line_mod() {
-    with_default_globals(|| {
-        let sess = ParseSess::new(FilePathMapping::empty());
-        let item = parse_item_from_source_str(
-            PathBuf::from("foo").into(),
-            "mod foo { struct S; mod this_does_not_exist; }".to_owned(),
-            &sess,
-        ).unwrap().unwrap();
-
-        if let ast::ItemKind::Mod(ref m) = item.kind {
-            assert!(m.items.len() == 2);
-        } else {
-            panic!();
-        }
-    });
-}
-
-#[test]
-fn eqmodws() {
-    assert_eq!(matches_codepattern("",""),true);
-    assert_eq!(matches_codepattern("","a"),false);
-    assert_eq!(matches_codepattern("a",""),false);
-    assert_eq!(matches_codepattern("a","a"),true);
-    assert_eq!(matches_codepattern("a b","a   \n\t\r  b"),true);
-    assert_eq!(matches_codepattern("a b ","a   \n\t\r  b"),true);
-    assert_eq!(matches_codepattern("a b","a   \n\t\r  b "),false);
-    assert_eq!(matches_codepattern("a   b","a b"),true);
-    assert_eq!(matches_codepattern("ab","a b"),false);
-    assert_eq!(matches_codepattern("a   b","ab"),true);
-    assert_eq!(matches_codepattern(" a   b","ab"),true);
-}
-
-#[test]
-fn pattern_whitespace() {
-    assert_eq!(matches_codepattern("","\x0C"), false);
-    assert_eq!(matches_codepattern("a b ","a   \u{0085}\n\t\r  b"),true);
-    assert_eq!(matches_codepattern("a b","a   \u{0085}\n\t\r  b "),false);
-}
-
-#[test]
-fn non_pattern_whitespace() {
-    // These have the property 'White_Space' but not 'Pattern_White_Space'
-    assert_eq!(matches_codepattern("a b","a\u{2002}b"), false);
-    assert_eq!(matches_codepattern("a   b","a\u{2002}b"), false);
-    assert_eq!(matches_codepattern("\u{205F}a   b","ab"), false);
-    assert_eq!(matches_codepattern("a  \u{3000}b","ab"), false);
-}
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 2203e8d9d06..b2e8d8526fd 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -1,6 +1,6 @@
 use crate::ast::{self, BlockCheckMode, PatKind, RangeEnd, RangeSyntax};
 use crate::ast::{SelfKind, GenericBound, TraitBoundModifier};
-use crate::ast::{Attribute, MacDelimiter, GenericArg};
+use crate::ast::{Attribute, GenericArg, MacArgs};
 use crate::util::parser::{self, AssocOp, Fixity};
 use crate::util::comments;
 use crate::attr;
@@ -317,11 +317,11 @@ pub fn token_to_string(token: &Token) -> String {
 }
 
 fn token_to_string_ext(token: &Token, convert_dollar_crate: bool) -> String {
-    let convert_dollar_crate = if convert_dollar_crate { Some(token.span) } else { None };
+    let convert_dollar_crate = convert_dollar_crate.then_some(token.span);
     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),
@@ -639,17 +639,22 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
 
     fn print_attr_item(&mut self, item: &ast::AttrItem, span: Span) {
         self.ibox(0);
-        match item.tokens.trees().next() {
-            Some(TokenTree::Delimited(_, delim, tts)) => {
-                self.print_mac_common(
-                    Some(MacHeader::Path(&item.path)), false, None, delim, tts, true, span
-                );
-            }
-            tree => {
+        match &item.args {
+            MacArgs::Delimited(_, delim, tokens) => self.print_mac_common(
+                Some(MacHeader::Path(&item.path)),
+                false,
+                None,
+                delim.to_token(),
+                tokens.clone(),
+                true,
+                span,
+            ),
+            MacArgs::Empty | MacArgs::Eq(..) => {
                 self.print_path(&item.path, false, 0);
-                if tree.is_some() {
+                if let MacArgs::Eq(_, tokens) = &item.args {
                     self.space();
-                    self.print_tts(item.tokens.clone(), true);
+                    self.word_space("=");
+                    self.print_tts(tokens.clone(), true);
                 }
             }
         }
@@ -939,8 +944,11 @@ impl<'a> State<'a> {
         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(e), |e| e.span)
     }
 
-    crate fn print_mod(&mut self, _mod: &ast::Mod,
-                       attrs: &[ast::Attribute]) {
+    pub fn print_mod(
+        &mut self,
+        _mod: &ast::Mod,
+        attrs: &[ast::Attribute],
+    ) {
         self.print_inner_attributes(attrs);
         for item in &_mod.items {
             self.print_item(item);
@@ -955,7 +963,7 @@ 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();
@@ -970,7 +978,7 @@ 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 {
@@ -981,16 +989,12 @@ impl<'a> State<'a> {
             }
             ast::TyKind::Ptr(ref mt) => {
                 self.s.word("*");
-                match mt.mutbl {
-                    ast::Mutability::Mutable => self.word_nbsp("mut"),
-                    ast::Mutability::Immutable => self.word_nbsp("const"),
-                }
-                self.print_type(&mt.ty);
+                self.print_mt(mt, true);
             }
             ast::TyKind::Rptr(ref lifetime, ref mt) => {
                 self.s.word("&");
                 self.print_opt_lifetime(lifetime);
-                self.print_mt(mt);
+                self.print_mt(mt, false);
             }
             ast::TyKind::Never => {
                 self.s.word("!");
@@ -1010,7 +1014,7 @@ impl<'a> State<'a> {
                 self.pclose();
             }
             ast::TyKind::BareFn(ref f) => {
-                self.print_ty_fn(f.abi,
+                self.print_ty_fn(f.ext,
                                  f.unsafety,
                                  &f.decl,
                                  None,
@@ -1098,9 +1102,8 @@ impl<'a> State<'a> {
             }
             ast::ForeignItemKind::Macro(ref m) => {
                 self.print_mac(m);
-                match m.delim {
-                    MacDelimiter::Brace => {},
-                    _ => self.s.word(";")
+                if m.args.need_semicolon() {
+                    self.s.word(";");
                 }
             }
         }
@@ -1229,7 +1232,10 @@ impl<'a> State<'a> {
             }
             ast::ItemKind::ForeignMod(ref nmod) => {
                 self.head("extern");
-                self.print_abi(nmod.abi);
+                if let Some(abi) = nmod.abi {
+                    self.print_literal(&abi.as_lit());
+                    self.nbsp();
+                }
                 self.bopen();
                 self.print_foreign_mod(nmod, &item.attrs);
                 self.bclose(item.span);
@@ -1252,19 +1258,6 @@ impl<'a> State<'a> {
                 self.s.word(";");
                 self.end(); // end the outer ibox
             }
-            ast::ItemKind::OpaqueTy(ref bounds, ref generics) => {
-                self.head(visibility_qualified(&item.vis, "type"));
-                self.print_ident(item.ident);
-                self.word_space("= impl");
-                self.print_generic_params(&generics.params);
-                self.end(); // end the inner ibox
-
-                self.print_where_clause(&generics.where_clause);
-                self.s.space();
-                self.print_type_bounds(":", bounds);
-                self.s.word(";");
-                self.end(); // end the outer ibox
-            }
             ast::ItemKind::Enum(ref enum_definition, ref params) => {
                 self.print_enum_def(
                     enum_definition,
@@ -1372,9 +1365,8 @@ impl<'a> State<'a> {
             }
             ast::ItemKind::Mac(ref mac) => {
                 self.print_mac(mac);
-                match mac.delim {
-                    MacDelimiter::Brace => {}
-                    _ => self.s.word(";"),
+                if mac.args.need_semicolon() {
+                    self.s.word(";");
                 }
             }
             ast::ItemKind::MacroDef(ref macro_def) => {
@@ -1388,8 +1380,8 @@ impl<'a> State<'a> {
                     Some(MacHeader::Keyword(kw)),
                     has_bang,
                     Some(item.ident),
-                    DelimToken::Brace,
-                    macro_def.stream(),
+                    macro_def.body.delim(),
+                    macro_def.body.inner_tokens(),
                     true,
                     item.span,
                 );
@@ -1589,9 +1581,8 @@ impl<'a> State<'a> {
             }
             ast::TraitItemKind::Macro(ref mac) => {
                 self.print_mac(mac);
-                match mac.delim {
-                    MacDelimiter::Brace => {}
-                    _ => self.s.word(";"),
+                if mac.args.need_semicolon() {
+                    self.s.word(";");
                 }
             }
         }
@@ -1617,18 +1608,10 @@ impl<'a> State<'a> {
             ast::ImplItemKind::TyAlias(ref ty) => {
                 self.print_associated_type(ii.ident, None, Some(ty));
             }
-            ast::ImplItemKind::OpaqueTy(ref bounds) => {
-                self.word_space("type");
-                self.print_ident(ii.ident);
-                self.word_space("= impl");
-                self.print_type_bounds(":", bounds);
-                self.s.word(";");
-            }
             ast::ImplItemKind::Macro(ref mac) => {
                 self.print_mac(mac);
-                match mac.delim {
-                    MacDelimiter::Brace => {}
-                    _ => self.s.word(";"),
+                if mac.args.need_semicolon() {
+                    self.s.word(";");
                 }
             }
         }
@@ -1793,10 +1776,10 @@ impl<'a> State<'a> {
             Some(MacHeader::Path(&m.path)),
             true,
             None,
-            m.delim.to_token(),
-            m.stream(),
+            m.args.delim(),
+            m.args.inner_tokens(),
             true,
-            m.span,
+            m.span(),
         );
     }
 
@@ -1988,14 +1971,21 @@ impl<'a> State<'a> {
     }
 
     fn print_expr_addr_of(&mut self,
+                          kind: ast::BorrowKind,
                           mutability: ast::Mutability,
                           expr: &ast::Expr) {
         self.s.word("&");
-        self.print_mutability(mutability);
+        match kind {
+            ast::BorrowKind::Ref => self.print_mutability(mutability, false),
+            ast::BorrowKind::Raw => {
+                self.word_nbsp("raw");
+                self.print_mutability(mutability, true);
+            }
+        }
         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)
     }
 
@@ -2042,8 +2032,8 @@ impl<'a> State<'a> {
             ast::ExprKind::Unary(op, ref expr) => {
                 self.print_expr_unary(op, expr);
             }
-            ast::ExprKind::AddrOf(m, ref expr) => {
-                self.print_expr_addr_of(m, expr);
+            ast::ExprKind::AddrOf(k, m, ref expr) => {
+                self.print_expr_addr_of(k, m, expr);
             }
             ast::ExprKind::Lit(ref lit) => {
                 self.print_literal(lit);
@@ -2332,7 +2322,7 @@ 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())
     }
 
@@ -2375,7 +2365,7 @@ impl<'a> State<'a> {
                 match binding_mode {
                     ast::BindingMode::ByRef(mutbl) => {
                         self.word_nbsp("ref");
-                        self.print_mutability(mutbl);
+                        self.print_mutability(mutbl, false);
                     }
                     ast::BindingMode::ByValue(ast::Mutability::Immutable) => {}
                     ast::BindingMode::ByValue(ast::Mutability::Mutable) => {
@@ -2518,17 +2508,17 @@ impl<'a> State<'a> {
     fn print_explicit_self(&mut self, explicit_self: &ast::ExplicitSelf) {
         match explicit_self.node {
             SelfKind::Value(m) => {
-                self.print_mutability(m);
+                self.print_mutability(m, false);
                 self.s.word("self")
             }
             SelfKind::Region(ref lt, m) => {
                 self.s.word("&");
                 self.print_opt_lifetime(lt);
-                self.print_mutability(m);
+                self.print_mutability(m, false);
                 self.s.word("self")
             }
             SelfKind::Explicit(ref typ, m) => {
-                self.print_mutability(m);
+                self.print_mutability(m, false);
                 self.s.word("self");
                 self.word_space(":");
                 self.print_type(typ)
@@ -2601,7 +2591,7 @@ 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;
@@ -2760,15 +2750,15 @@ impl<'a> State<'a> {
         }
     }
 
-    crate fn print_mutability(&mut self, mutbl: ast::Mutability) {
+    pub fn print_mutability(&mut self, mutbl: ast::Mutability, print_const: bool) {
         match mutbl {
             ast::Mutability::Mutable => self.word_nbsp("mut"),
-            ast::Mutability::Immutable => {},
+            ast::Mutability::Immutable => if print_const { self.word_nbsp("const"); },
         }
     }
 
-    crate fn print_mt(&mut self, mt: &ast::MutTy) {
-        self.print_mutability(mt.mutbl);
+    crate fn print_mt(&mut self, mt: &ast::MutTy, print_const: bool) {
+        self.print_mutability(mt.mutbl, print_const);
         self.print_type(&mt.ty)
     }
 
@@ -2822,7 +2812,7 @@ impl<'a> State<'a> {
     }
 
     crate fn print_ty_fn(&mut self,
-                       abi: ast::Abi,
+                       ext: ast::Extern,
                        unsafety: ast::Unsafety,
                        decl: &ast::FnDecl,
                        name: Option<ast::Ident>,
@@ -2842,7 +2832,7 @@ impl<'a> State<'a> {
             span: syntax_pos::DUMMY_SP,
         };
         self.print_fn(decl,
-                      ast::FnHeader { unsafety, abi, ..ast::FnHeader::default() },
+                      ast::FnHeader { unsafety, ext, ..ast::FnHeader::default() },
                       name,
                       &generics,
                       &source_map::dummy_spanned(ast::VisibilityKind::Inherited));
@@ -2883,18 +2873,21 @@ impl<'a> State<'a> {
         self.print_asyncness(header.asyncness.node);
         self.print_unsafety(header.unsafety);
 
-        if header.abi.symbol != sym::Rust {
-            self.word_nbsp("extern");
-            self.print_abi(header.abi);
+        match header.ext {
+            ast::Extern::None => {}
+            ast::Extern::Implicit => {
+                self.word_nbsp("extern");
+            }
+            ast::Extern::Explicit(abi) => {
+                self.word_nbsp("extern");
+                self.print_literal(&abi.as_lit());
+                self.nbsp();
+            }
         }
 
         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 2c6dd0fb1c6..d7725acb5d4 100644
--- a/src/libsyntax/print/pprust/tests.rs
+++ b/src/libsyntax/print/pprust/tests.rs
@@ -50,6 +50,7 @@ fn test_variant_to_string() {
 
         let var = ast::Variant {
             ident,
+            vis: source_map::respan(syntax_pos::DUMMY_SP, ast::VisibilityKind::Inherited),
             attrs: Vec::new(),
             id: ast::DUMMY_NODE_ID,
             data: ast::VariantData::Unit(ast::DUMMY_NODE_ID),
diff --git a/src/libsyntax/sess.rs b/src/libsyntax/sess.rs
deleted file mode 100644
index faad3e4af1e..00000000000
--- a/src/libsyntax/sess.rs
+++ /dev/null
@@ -1,169 +0,0 @@
-//! Contains `ParseSess` which holds state living beyond what one `Parser` might.
-//! It also serves as an input to the parser itself.
-
-use crate::ast::{CrateConfig, NodeId};
-use crate::early_buffered_lints::{BufferedEarlyLint, BufferedEarlyLintId};
-use crate::source_map::{SourceMap, FilePathMapping};
-use crate::feature_gate::UnstableFeatures;
-
-use errors::{Applicability, emitter::SilentEmitter, Handler, ColorConfig, DiagnosticBuilder};
-use rustc_data_structures::fx::{FxHashSet, FxHashMap};
-use rustc_data_structures::sync::{Lrc, Lock, Once};
-use syntax_pos::{Symbol, Span, MultiSpan};
-use syntax_pos::edition::Edition;
-use syntax_pos::hygiene::ExpnId;
-
-use std::path::PathBuf;
-use std::str;
-
-/// Collected spans during parsing for places where a certain feature was
-/// used and should be feature gated accordingly in `check_crate`.
-#[derive(Default)]
-pub struct GatedSpans {
-    pub spans: Lock<FxHashMap<Symbol, Vec<Span>>>,
-}
-
-impl GatedSpans {
-    /// Feature gate the given `span` under the given `feature`
-    /// which is same `Symbol` used in `active.rs`.
-    pub fn gate(&self, feature: Symbol, span: Span) {
-        self.spans
-            .borrow_mut()
-            .entry(feature)
-            .or_default()
-            .push(span);
-    }
-
-    /// Ungate the last span under the given `feature`.
-    /// Panics if the given `span` wasn't the last one.
-    ///
-    /// Using this is discouraged unless you have a really good reason to.
-    pub fn ungate_last(&self, feature: Symbol, span: Span) {
-        let removed_span = self.spans
-            .borrow_mut()
-            .entry(feature)
-            .or_default()
-            .pop()
-            .unwrap();
-        debug_assert_eq!(span, removed_span);
-    }
-
-    /// Is the provided `feature` gate ungated currently?
-    ///
-    /// Using this is discouraged unless you have a really good reason to.
-    pub fn is_ungated(&self, feature: Symbol) -> bool {
-        self.spans
-            .borrow()
-            .get(&feature)
-            .map_or(true, |spans| spans.is_empty())
-    }
-
-    /// Prepend the given set of `spans` onto the set in `self`.
-    pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
-        let mut inner = self.spans.borrow_mut();
-        for (gate, mut gate_spans) in inner.drain() {
-            spans.entry(gate).or_default().append(&mut gate_spans);
-        }
-        *inner = spans;
-    }
-}
-
-/// Info about a parsing session.
-pub struct ParseSess {
-    pub span_diagnostic: Handler,
-    crate 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>>,
-    source_map: Lrc<SourceMap>,
-    pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
-    /// Contains the spans of block expressions that could have been incomplete based on the
-    /// operation token that followed it, but that the parser cannot identify without further
-    /// analysis.
-    pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
-    pub injected_crate_name: Once<Symbol>,
-    pub gated_spans: GatedSpans,
-    /// The parser has reached `Eof` due to an unclosed brace. Used to silence unnecessary errors.
-    pub reached_eof: Lock<bool>,
-}
-
-impl ParseSess {
-    pub fn new(file_path_mapping: FilePathMapping) -> Self {
-        let cm = Lrc::new(SourceMap::new(file_path_mapping));
-        let handler = Handler::with_tty_emitter(
-            ColorConfig::Auto,
-            true,
-            None,
-            Some(cm.clone()),
-        );
-        ParseSess::with_span_handler(handler, cm)
-    }
-
-    pub fn with_span_handler(handler: Handler, source_map: Lrc<SourceMap>) -> Self {
-        Self {
-            span_diagnostic: handler,
-            unstable_features: UnstableFeatures::from_environment(),
-            config: FxHashSet::default(),
-            edition: ExpnId::root().expn_data().edition,
-            missing_fragment_specifiers: Lock::new(FxHashSet::default()),
-            raw_identifier_spans: Lock::new(Vec::new()),
-            included_mod_stack: Lock::new(vec![]),
-            source_map,
-            buffered_lints: Lock::new(vec![]),
-            ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
-            injected_crate_name: Once::new(),
-            gated_spans: GatedSpans::default(),
-            reached_eof: Lock::new(false),
-        }
-    }
-
-    pub fn with_silent_emitter() -> Self {
-        let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let handler = Handler::with_emitter(false, None, Box::new(SilentEmitter));
-        ParseSess::with_span_handler(handler, cm)
-    }
-
-    #[inline]
-    pub fn source_map(&self) -> &SourceMap {
-        &self.source_map
-    }
-
-    pub fn buffer_lint(
-        &self,
-        lint_id: BufferedEarlyLintId,
-        span: impl Into<MultiSpan>,
-        id: NodeId,
-        msg: &str,
-    ) {
-        self.buffered_lints.with_lock(|buffered_lints| {
-            buffered_lints.push(BufferedEarlyLint{
-                span: span.into(),
-                id,
-                msg: msg.into(),
-                lint_id,
-            });
-        });
-    }
-
-    /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
-    /// parser to continue parsing the following operation as part of the same expression.
-    pub fn expr_parentheses_needed(
-        &self,
-        err: &mut DiagnosticBuilder<'_>,
-        span: Span,
-        alt_snippet: Option<String>,
-    ) {
-        if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
-            err.span_suggestion(
-                span,
-                "parentheses are required to parse this as an expression",
-                format!("({})", snippet),
-                Applicability::MachineApplicable,
-            );
-        }
-    }
-}
diff --git a/src/libsyntax/source_map.rs b/src/libsyntax/source_map.rs
deleted file mode 100644
index d9f618602a4..00000000000
--- a/src/libsyntax/source_map.rs
+++ /dev/null
@@ -1,1035 +0,0 @@
-//! The `SourceMap` tracks all the source code used within a single crate, mapping
-//! from integer byte positions to the original source code location. Each bit
-//! of source parsed during crate parsing (typically files, in-memory strings,
-//! or various bits of macro expansion) cover a continuous range of bytes in the
-//! `SourceMap` and are represented by `SourceFile`s. Byte positions are stored in
-//! `Span` and used pervasively in the compiler. They are absolute positions
-//! within the `SourceMap`, which upon request can be converted to line and column
-//! information, source code snippets, etc.
-
-pub use syntax_pos::*;
-pub use syntax_pos::hygiene::{ExpnKind, ExpnData};
-
-use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::stable_hasher::StableHasher;
-use rustc_data_structures::sync::{Lrc, Lock, LockGuard, MappedLockGuard};
-use std::cmp;
-use std::hash::Hash;
-use std::path::{Path, PathBuf};
-
-use std::env;
-use std::fs;
-use std::io;
-use log::debug;
-
-use errors::SourceMapper;
-
-#[cfg(test)]
-mod tests;
-
-/// Returns the span itself if it doesn't come from a macro expansion,
-/// otherwise return the call site span up to the `enclosing_sp` by
-/// following the `expn_data` chain.
-pub fn original_sp(sp: Span, enclosing_sp: Span) -> Span {
-    let expn_data1 = sp.ctxt().outer_expn_data();
-    let expn_data2 = enclosing_sp.ctxt().outer_expn_data();
-    if expn_data1.is_root() ||
-       !expn_data2.is_root() && expn_data1.call_site == expn_data2.call_site {
-        sp
-    } else {
-        original_sp(expn_data1.call_site, enclosing_sp)
-    }
-}
-
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug, Copy)]
-pub struct Spanned<T> {
-    pub node: T,
-    pub span: Span,
-}
-
-pub fn respan<T>(sp: Span, t: T) -> Spanned<T> {
-    Spanned {node: t, span: sp}
-}
-
-pub fn dummy_spanned<T>(t: T) -> Spanned<T> {
-    respan(DUMMY_SP, t)
-}
-
-// _____________________________________________________________________________
-// SourceFile, MultiByteChar, FileName, FileLines
-//
-
-/// An abstraction over the fs operations used by the Parser.
-pub trait FileLoader {
-    /// Query the existence of a file.
-    fn file_exists(&self, path: &Path) -> bool;
-
-    /// Returns an absolute path to a file, if possible.
-    fn abs_path(&self, path: &Path) -> Option<PathBuf>;
-
-    /// Read the contents of an UTF-8 file into memory.
-    fn read_file(&self, path: &Path) -> io::Result<String>;
-}
-
-/// A FileLoader that uses std::fs to load real files.
-pub struct RealFileLoader;
-
-impl FileLoader for RealFileLoader {
-    fn file_exists(&self, path: &Path) -> bool {
-        fs::metadata(path).is_ok()
-    }
-
-    fn abs_path(&self, path: &Path) -> Option<PathBuf> {
-        if path.is_absolute() {
-            Some(path.to_path_buf())
-        } else {
-            env::current_dir()
-                .ok()
-                .map(|cwd| cwd.join(path))
-        }
-    }
-
-    fn read_file(&self, path: &Path) -> io::Result<String> {
-        fs::read_to_string(path)
-    }
-}
-
-// This is a `SourceFile` identifier that is used to correlate `SourceFile`s between
-// subsequent compilation sessions (which is something we need to do during
-// incremental compilation).
-#[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug)]
-pub struct StableSourceFileId(u128);
-
-impl StableSourceFileId {
-    pub fn new(source_file: &SourceFile) -> StableSourceFileId {
-        StableSourceFileId::new_from_pieces(&source_file.name,
-                                            source_file.name_was_remapped,
-                                            source_file.unmapped_path.as_ref())
-    }
-
-    pub fn new_from_pieces(name: &FileName,
-                           name_was_remapped: bool,
-                           unmapped_path: Option<&FileName>) -> StableSourceFileId {
-        let mut hasher = StableHasher::new();
-
-        name.hash(&mut hasher);
-        name_was_remapped.hash(&mut hasher);
-        unmapped_path.hash(&mut hasher);
-
-        StableSourceFileId(hasher.finish())
-    }
-}
-
-// _____________________________________________________________________________
-// SourceMap
-//
-
-#[derive(Default)]
-pub(super) struct SourceMapFiles {
-    source_files: Vec<Lrc<SourceFile>>,
-    stable_id_to_source_file: FxHashMap<StableSourceFileId, Lrc<SourceFile>>
-}
-
-pub struct SourceMap {
-    files: Lock<SourceMapFiles>,
-    file_loader: Box<dyn FileLoader + Sync + Send>,
-    // This is used to apply the file path remapping as specified via
-    // `--remap-path-prefix` to all `SourceFile`s allocated within this `SourceMap`.
-    path_mapping: FilePathMapping,
-}
-
-impl SourceMap {
-    pub fn new(path_mapping: FilePathMapping) -> SourceMap {
-        SourceMap {
-            files: Default::default(),
-            file_loader: Box::new(RealFileLoader),
-            path_mapping,
-        }
-    }
-
-    pub fn with_file_loader(file_loader: Box<dyn FileLoader + Sync + Send>,
-                            path_mapping: FilePathMapping)
-                            -> SourceMap {
-        SourceMap {
-            files: Default::default(),
-            file_loader,
-            path_mapping,
-        }
-    }
-
-    pub fn path_mapping(&self) -> &FilePathMapping {
-        &self.path_mapping
-    }
-
-    pub fn file_exists(&self, path: &Path) -> bool {
-        self.file_loader.file_exists(path)
-    }
-
-    pub fn load_file(&self, path: &Path) -> io::Result<Lrc<SourceFile>> {
-        let src = self.file_loader.read_file(path)?;
-        let filename = path.to_owned().into();
-        Ok(self.new_source_file(filename, src))
-    }
-
-    /// Loads source file as a binary blob.
-    ///
-    /// Unlike `load_file`, guarantees that no normalization like BOM-removal
-    /// takes place.
-    pub fn load_binary_file(&self, path: &Path) -> io::Result<Vec<u8>> {
-        // Ideally, this should use `self.file_loader`, but it can't
-        // deal with binary files yet.
-        let bytes = fs::read(path)?;
-
-        // We need to add file to the `SourceMap`, so that it is present
-        // in dep-info. There's also an edge case that file might be both
-        // loaded as a binary via `include_bytes!` and as proper `SourceFile`
-        // via `mod`, so we try to use real file contents and not just an
-        // empty string.
-        let text = std::str::from_utf8(&bytes).unwrap_or("")
-            .to_string();
-        self.new_source_file(path.to_owned().into(), text);
-        Ok(bytes)
-    }
-
-    pub fn files(&self) -> MappedLockGuard<'_, Vec<Lrc<SourceFile>>> {
-        LockGuard::map(self.files.borrow(), |files| &mut files.source_files)
-    }
-
-    pub fn source_file_by_stable_id(&self, stable_id: StableSourceFileId) ->
-    Option<Lrc<SourceFile>> {
-        self.files.borrow().stable_id_to_source_file.get(&stable_id).map(|sf| sf.clone())
-    }
-
-    fn next_start_pos(&self) -> usize {
-        match self.files.borrow().source_files.last() {
-            None => 0,
-            // Add one so there is some space between files. This lets us distinguish
-            // positions in the `SourceMap`, even in the presence of zero-length files.
-            Some(last) => last.end_pos.to_usize() + 1,
-        }
-    }
-
-    /// Creates a new `SourceFile`.
-    /// If a file already exists in the `SourceMap` with the same ID, that file is returned
-    /// unmodified.
-    pub fn new_source_file(&self, filename: FileName, src: String) -> Lrc<SourceFile> {
-        self.try_new_source_file(filename, src)
-            .unwrap_or_else(|OffsetOverflowError| {
-                eprintln!("fatal error: rustc does not support files larger than 4GB");
-                errors::FatalError.raise()
-            })
-    }
-
-    fn try_new_source_file(
-        &self,
-        filename: FileName,
-        src: String
-    ) -> Result<Lrc<SourceFile>, OffsetOverflowError> {
-        let start_pos = self.next_start_pos();
-
-        // The path is used to determine the directory for loading submodules and
-        // include files, so it must be before remapping.
-        // Note that filename may not be a valid path, eg it may be `<anon>` etc,
-        // but this is okay because the directory determined by `path.pop()` will
-        // be empty, so the working directory will be used.
-        let unmapped_path = filename.clone();
-
-        let (filename, was_remapped) = match filename {
-            FileName::Real(filename) => {
-                let (filename, was_remapped) = self.path_mapping.map_prefix(filename);
-                (FileName::Real(filename), was_remapped)
-            },
-            other => (other, false),
-        };
-
-        let file_id = StableSourceFileId::new_from_pieces(&filename,
-                                                       was_remapped,
-                                                       Some(&unmapped_path));
-
-        let lrc_sf = match self.source_file_by_stable_id(file_id) {
-            Some(lrc_sf) => lrc_sf,
-            None => {
-                let source_file = Lrc::new(SourceFile::new(
-                    filename,
-                    was_remapped,
-                    unmapped_path,
-                    src,
-                    Pos::from_usize(start_pos),
-                )?);
-
-                let mut files = self.files.borrow_mut();
-
-                files.source_files.push(source_file.clone());
-                files.stable_id_to_source_file.insert(file_id, source_file.clone());
-
-                source_file
-            }
-        };
-        Ok(lrc_sf)
-    }
-
-    /// Allocates a new `SourceFile` representing a source file from an external
-    /// crate. The source code of such an "imported `SourceFile`" is not available,
-    /// but we still know enough to generate accurate debuginfo location
-    /// information for things inlined from other crates.
-    pub fn new_imported_source_file(
-        &self,
-        filename: FileName,
-        name_was_remapped: bool,
-        crate_of_origin: u32,
-        src_hash: u128,
-        name_hash: u128,
-        source_len: usize,
-        mut file_local_lines: Vec<BytePos>,
-        mut file_local_multibyte_chars: Vec<MultiByteChar>,
-        mut file_local_non_narrow_chars: Vec<NonNarrowChar>,
-        mut file_local_normalized_pos: Vec<NormalizedPos>,
-    ) -> Lrc<SourceFile> {
-        let start_pos = self.next_start_pos();
-
-        let end_pos = Pos::from_usize(start_pos + source_len);
-        let start_pos = Pos::from_usize(start_pos);
-
-        for pos in &mut file_local_lines {
-            *pos = *pos + start_pos;
-        }
-
-        for mbc in &mut file_local_multibyte_chars {
-            mbc.pos = mbc.pos + start_pos;
-        }
-
-        for swc in &mut file_local_non_narrow_chars {
-            *swc = *swc + start_pos;
-        }
-
-        for nc in &mut file_local_normalized_pos {
-            nc.pos = nc.pos + start_pos;
-        }
-
-        let source_file = Lrc::new(SourceFile {
-            name: filename,
-            name_was_remapped,
-            unmapped_path: None,
-            crate_of_origin,
-            src: None,
-            src_hash,
-            external_src: Lock::new(ExternalSource::AbsentOk),
-            start_pos,
-            end_pos,
-            lines: file_local_lines,
-            multibyte_chars: file_local_multibyte_chars,
-            non_narrow_chars: file_local_non_narrow_chars,
-            normalized_pos: file_local_normalized_pos,
-            name_hash,
-        });
-
-        let mut files = self.files.borrow_mut();
-
-        files.source_files.push(source_file.clone());
-        files.stable_id_to_source_file.insert(StableSourceFileId::new(&source_file),
-                                              source_file.clone());
-
-        source_file
-    }
-
-    pub fn mk_substr_filename(&self, sp: Span) -> String {
-        let pos = self.lookup_char_pos(sp.lo());
-        format!("<{}:{}:{}>",
-                 pos.file.name,
-                 pos.line,
-                 pos.col.to_usize() + 1)
-    }
-
-    // If there is a doctest offset, applies it to the line.
-    pub fn doctest_offset_line(&self, file: &FileName, orig: usize) -> usize {
-        return match file {
-            FileName::DocTest(_, offset) => {
-                return if *offset >= 0 {
-                    orig + *offset as usize
-                } else {
-                    orig - (-(*offset)) as usize
-                }
-            },
-            _ => orig
-        }
-    }
-
-    /// Looks up source information about a `BytePos`.
-    pub fn lookup_char_pos(&self, pos: BytePos) -> Loc {
-        let chpos = self.bytepos_to_file_charpos(pos);
-        match self.lookup_line(pos) {
-            Ok(SourceFileAndLine { sf: f, line: a }) => {
-                let line = a + 1; // Line numbers start at 1
-                let linebpos = f.lines[a];
-                let linechpos = self.bytepos_to_file_charpos(linebpos);
-                let col = chpos - linechpos;
-
-                let col_display = {
-                    let start_width_idx = f
-                        .non_narrow_chars
-                        .binary_search_by_key(&linebpos, |x| x.pos())
-                        .unwrap_or_else(|x| x);
-                    let end_width_idx = f
-                        .non_narrow_chars
-                        .binary_search_by_key(&pos, |x| x.pos())
-                        .unwrap_or_else(|x| x);
-                    let special_chars = end_width_idx - start_width_idx;
-                    let non_narrow: usize = f
-                        .non_narrow_chars[start_width_idx..end_width_idx]
-                        .into_iter()
-                        .map(|x| x.width())
-                        .sum();
-                    col.0 - special_chars + non_narrow
-                };
-                debug!("byte pos {:?} is on the line at byte pos {:?}",
-                       pos, linebpos);
-                debug!("char pos {:?} is on the line at char pos {:?}",
-                       chpos, linechpos);
-                debug!("byte is on line: {}", line);
-                assert!(chpos >= linechpos);
-                Loc {
-                    file: f,
-                    line,
-                    col,
-                    col_display,
-                }
-            }
-            Err(f) => {
-                let col_display = {
-                    let end_width_idx = f
-                        .non_narrow_chars
-                        .binary_search_by_key(&pos, |x| x.pos())
-                        .unwrap_or_else(|x| x);
-                    let non_narrow: usize = f
-                        .non_narrow_chars[0..end_width_idx]
-                        .into_iter()
-                        .map(|x| x.width())
-                        .sum();
-                    chpos.0 - end_width_idx + non_narrow
-                };
-                Loc {
-                    file: f,
-                    line: 0,
-                    col: chpos,
-                    col_display,
-                }
-            }
-        }
-    }
-
-    // If the corresponding `SourceFile` is empty, does not return a line number.
-    pub fn lookup_line(&self, pos: BytePos) -> Result<SourceFileAndLine, Lrc<SourceFile>> {
-        let idx = self.lookup_source_file_idx(pos);
-
-        let f = (*self.files.borrow().source_files)[idx].clone();
-
-        match f.lookup_line(pos) {
-            Some(line) => Ok(SourceFileAndLine { sf: f, line }),
-            None => Err(f)
-        }
-    }
-
-    /// Returns `Some(span)`, a union of the LHS and RHS span. The LHS must precede the RHS. If
-    /// there are gaps between LHS and RHS, the resulting union will cross these gaps.
-    /// For this to work,
-    ///
-    ///    * the syntax contexts of both spans much match,
-    ///    * the LHS span needs to end on the same line the RHS span begins,
-    ///    * the LHS span must start at or before the RHS span.
-    pub fn merge_spans(&self, sp_lhs: Span, sp_rhs: Span) -> Option<Span> {
-        // Ensure we're at the same expansion ID.
-        if sp_lhs.ctxt() != sp_rhs.ctxt() {
-            return None;
-        }
-
-        let lhs_end = match self.lookup_line(sp_lhs.hi()) {
-            Ok(x) => x,
-            Err(_) => return None
-        };
-        let rhs_begin = match self.lookup_line(sp_rhs.lo()) {
-            Ok(x) => x,
-            Err(_) => return None
-        };
-
-        // If we must cross lines to merge, don't merge.
-        if lhs_end.line != rhs_begin.line {
-            return None;
-        }
-
-        // Ensure these follow the expected order and that we don't overlap.
-        if (sp_lhs.lo() <= sp_rhs.lo()) && (sp_lhs.hi() <= sp_rhs.lo()) {
-            Some(sp_lhs.to(sp_rhs))
-        } else {
-            None
-        }
-    }
-
-    pub fn span_to_string(&self, sp: Span) -> String {
-        if self.files.borrow().source_files.is_empty() && sp.is_dummy() {
-            return "no-location".to_string();
-        }
-
-        let lo = self.lookup_char_pos(sp.lo());
-        let hi = self.lookup_char_pos(sp.hi());
-        format!("{}:{}:{}: {}:{}",
-            lo.file.name,
-            lo.line,
-            lo.col.to_usize() + 1,
-            hi.line,
-            hi.col.to_usize() + 1,
-        )
-    }
-
-    pub fn span_to_filename(&self, sp: Span) -> FileName {
-        self.lookup_char_pos(sp.lo()).file.name.clone()
-    }
-
-    pub fn span_to_unmapped_path(&self, sp: Span) -> FileName {
-        self.lookup_char_pos(sp.lo()).file.unmapped_path.clone()
-            .expect("`SourceMap::span_to_unmapped_path` called for imported `SourceFile`?")
-    }
-
-    pub fn is_multiline(&self, sp: Span) -> bool {
-        let lo = self.lookup_char_pos(sp.lo());
-        let hi = self.lookup_char_pos(sp.hi());
-        lo.line != hi.line
-    }
-
-    pub fn span_to_lines(&self, sp: Span) -> FileLinesResult {
-        debug!("span_to_lines(sp={:?})", sp);
-
-        let lo = self.lookup_char_pos(sp.lo());
-        debug!("span_to_lines: lo={:?}", lo);
-        let hi = self.lookup_char_pos(sp.hi());
-        debug!("span_to_lines: hi={:?}", hi);
-
-        if lo.file.start_pos != hi.file.start_pos {
-            return Err(SpanLinesError::DistinctSources(DistinctSources {
-                begin: (lo.file.name.clone(), lo.file.start_pos),
-                end: (hi.file.name.clone(), hi.file.start_pos),
-            }));
-        }
-        assert!(hi.line >= lo.line);
-
-        let mut lines = Vec::with_capacity(hi.line - lo.line + 1);
-
-        // The span starts partway through the first line,
-        // but after that it starts from offset 0.
-        let mut start_col = lo.col;
-
-        // For every line but the last, it extends from `start_col`
-        // and to the end of the line. Be careful because the line
-        // numbers in Loc are 1-based, so we subtract 1 to get 0-based
-        // lines.
-        for line_index in lo.line-1 .. hi.line-1 {
-            let line_len = lo.file.get_line(line_index)
-                                  .map(|s| s.chars().count())
-                                  .unwrap_or(0);
-            lines.push(LineInfo { line_index,
-                                  start_col,
-                                  end_col: CharPos::from_usize(line_len) });
-            start_col = CharPos::from_usize(0);
-        }
-
-        // For the last line, it extends from `start_col` to `hi.col`:
-        lines.push(LineInfo { line_index: hi.line - 1,
-                              start_col,
-                              end_col: hi.col });
-
-        Ok(FileLines {file: lo.file, lines})
-    }
-
-    /// Extracts the source surrounding the given `Span` using the `extract_source` function. The
-    /// extract function takes three arguments: a string slice containing the source, an index in
-    /// the slice for the beginning of the span and an index in the slice for the end of the span.
-    fn span_to_source<F>(&self, sp: Span, extract_source: F) -> Result<String, SpanSnippetError>
-        where F: Fn(&str, usize, usize) -> Result<String, SpanSnippetError>
-    {
-        let local_begin = self.lookup_byte_offset(sp.lo());
-        let local_end = self.lookup_byte_offset(sp.hi());
-
-        if local_begin.sf.start_pos != local_end.sf.start_pos {
-            return Err(SpanSnippetError::DistinctSources(DistinctSources {
-                begin: (local_begin.sf.name.clone(),
-                        local_begin.sf.start_pos),
-                end: (local_end.sf.name.clone(),
-                      local_end.sf.start_pos)
-            }));
-        } else {
-            self.ensure_source_file_source_present(local_begin.sf.clone());
-
-            let start_index = local_begin.pos.to_usize();
-            let end_index = local_end.pos.to_usize();
-            let source_len = (local_begin.sf.end_pos -
-                              local_begin.sf.start_pos).to_usize();
-
-            if start_index > end_index || end_index > source_len {
-                return Err(SpanSnippetError::MalformedForSourcemap(
-                    MalformedSourceMapPositions {
-                        name: local_begin.sf.name.clone(),
-                        source_len,
-                        begin_pos: local_begin.pos,
-                        end_pos: local_end.pos,
-                    }));
-            }
-
-            if let Some(ref src) = local_begin.sf.src {
-                return extract_source(src, start_index, end_index);
-            } else if let Some(src) = local_begin.sf.external_src.borrow().get_source() {
-                return extract_source(src, start_index, end_index);
-            } else {
-                return Err(SpanSnippetError::SourceNotAvailable {
-                    filename: local_begin.sf.name.clone()
-                });
-            }
-        }
-    }
-
-    /// Returns the source snippet as `String` corresponding to the given `Span`.
-    pub fn span_to_snippet(&self, sp: Span) -> Result<String, SpanSnippetError> {
-        self.span_to_source(sp, |src, start_index, end_index| src.get(start_index..end_index)
-            .map(|s| s.to_string())
-            .ok_or_else(|| SpanSnippetError::IllFormedSpan(sp)))
-    }
-
-    pub fn span_to_margin(&self, sp: Span) -> Option<usize> {
-        match self.span_to_prev_source(sp) {
-            Err(_) => None,
-            Ok(source) => source.split('\n').last().map(|last_line| {
-                last_line.len() - last_line.trim_start().len()
-            })
-        }
-    }
-
-    /// Returns the source snippet as `String` before the given `Span`.
-    pub fn span_to_prev_source(&self, sp: Span) -> Result<String, SpanSnippetError> {
-        self.span_to_source(sp, |src, start_index, _| src.get(..start_index)
-            .map(|s| s.to_string())
-            .ok_or_else(|| SpanSnippetError::IllFormedSpan(sp)))
-    }
-
-    /// Extends the given `Span` to just after the previous occurrence of `c`. Return the same span
-    /// if no character could be found or if an error occurred while retrieving the code snippet.
-    pub fn span_extend_to_prev_char(&self, sp: Span, c: char) -> Span {
-        if let Ok(prev_source) = self.span_to_prev_source(sp) {
-            let prev_source = prev_source.rsplit(c).nth(0).unwrap_or("").trim_start();
-            if !prev_source.is_empty() && !prev_source.contains('\n') {
-                return sp.with_lo(BytePos(sp.lo().0 - prev_source.len() as u32));
-            }
-        }
-
-        sp
-    }
-
-    /// Extends the given `Span` to just after the previous occurrence of `pat` when surrounded by
-    /// whitespace. Returns the same span if no character could be found or if an error occurred
-    /// while retrieving the code snippet.
-    pub fn span_extend_to_prev_str(&self, sp: Span, pat: &str, accept_newlines: bool) -> Span {
-        // assure that the pattern is delimited, to avoid the following
-        //     fn my_fn()
-        //           ^^^^ returned span without the check
-        //     ---------- correct span
-        for ws in &[" ", "\t", "\n"] {
-            let pat = pat.to_owned() + ws;
-            if let Ok(prev_source) = self.span_to_prev_source(sp) {
-                let prev_source = prev_source.rsplit(&pat).nth(0).unwrap_or("").trim_start();
-                if !prev_source.is_empty() && (!prev_source.contains('\n') || accept_newlines) {
-                    return sp.with_lo(BytePos(sp.lo().0 - prev_source.len() as u32));
-                }
-            }
-        }
-
-        sp
-    }
-
-    /// Given a `Span`, tries to get a shorter span ending before the first occurrence of `char`
-    /// `c`.
-    pub fn span_until_char(&self, sp: Span, c: char) -> Span {
-        match self.span_to_snippet(sp) {
-            Ok(snippet) => {
-                let snippet = snippet.split(c).nth(0).unwrap_or("").trim_end();
-                if !snippet.is_empty() && !snippet.contains('\n') {
-                    sp.with_hi(BytePos(sp.lo().0 + snippet.len() as u32))
-                } else {
-                    sp
-                }
-            }
-            _ => sp,
-        }
-    }
-
-    /// Given a `Span`, tries to get a shorter span ending just after the first occurrence of `char`
-    /// `c`.
-    pub fn span_through_char(&self, sp: Span, c: char) -> Span {
-        if let Ok(snippet) = self.span_to_snippet(sp) {
-            if let Some(offset) = snippet.find(c) {
-                return sp.with_hi(BytePos(sp.lo().0 + (offset + c.len_utf8()) as u32));
-            }
-        }
-        sp
-    }
-
-    /// Given a `Span`, gets a new `Span` covering the first token and all its trailing whitespace
-    /// or the original `Span`.
-    ///
-    /// If `sp` points to `"let mut x"`, then a span pointing at `"let "` will be returned.
-    pub fn span_until_non_whitespace(&self, sp: Span) -> Span {
-        let mut whitespace_found = false;
-
-        self.span_take_while(sp, |c| {
-            if !whitespace_found && c.is_whitespace() {
-                whitespace_found = true;
-            }
-
-            if whitespace_found && !c.is_whitespace() {
-                false
-            } else {
-                true
-            }
-        })
-    }
-
-    /// Given a `Span`, gets a new `Span` covering the first token without its trailing whitespace
-    /// or the original `Span` in case of error.
-    ///
-    /// If `sp` points to `"let mut x"`, then a span pointing at `"let"` will be returned.
-    pub fn span_until_whitespace(&self, sp: Span) -> Span {
-        self.span_take_while(sp, |c| !c.is_whitespace())
-    }
-
-    /// Given a `Span`, gets a shorter one until `predicate` yields `false`.
-    pub fn span_take_while<P>(&self, sp: Span, predicate: P) -> Span
-        where P: for <'r> FnMut(&'r char) -> bool
-    {
-        if let Ok(snippet) = self.span_to_snippet(sp) {
-            let offset = snippet.chars()
-                .take_while(predicate)
-                .map(|c| c.len_utf8())
-                .sum::<usize>();
-
-            sp.with_hi(BytePos(sp.lo().0 + (offset as u32)))
-        } else {
-            sp
-        }
-    }
-
-    pub fn def_span(&self, sp: Span) -> Span {
-        self.span_until_char(sp, '{')
-    }
-
-    /// Returns a new span representing just the start point of this span.
-    pub fn start_point(&self, sp: Span) -> Span {
-        let pos = sp.lo().0;
-        let width = self.find_width_of_character_at_span(sp, false);
-        let corrected_start_position = pos.checked_add(width).unwrap_or(pos);
-        let end_point = BytePos(cmp::max(corrected_start_position, sp.lo().0));
-        sp.with_hi(end_point)
-    }
-
-    /// Returns a new span representing just the end point of this span.
-    pub fn end_point(&self, sp: Span) -> Span {
-        let pos = sp.hi().0;
-
-        let width = self.find_width_of_character_at_span(sp, false);
-        let corrected_end_position = pos.checked_sub(width).unwrap_or(pos);
-
-        let end_point = BytePos(cmp::max(corrected_end_position, sp.lo().0));
-        sp.with_lo(end_point)
-    }
-
-    /// Returns a new span representing the next character after the end-point of this span.
-    pub fn next_point(&self, sp: Span) -> Span {
-        let start_of_next_point = sp.hi().0;
-
-        let width = self.find_width_of_character_at_span(sp, true);
-        // If the width is 1, then the next span should point to the same `lo` and `hi`. However,
-        // in the case of a multibyte character, where the width != 1, the next span should
-        // span multiple bytes to include the whole character.
-        let end_of_next_point = start_of_next_point.checked_add(
-            width - 1).unwrap_or(start_of_next_point);
-
-        let end_of_next_point = BytePos(cmp::max(sp.lo().0 + 1, end_of_next_point));
-        Span::new(BytePos(start_of_next_point), end_of_next_point, sp.ctxt())
-    }
-
-    /// Finds the width of a character, either before or after the provided span.
-    fn find_width_of_character_at_span(&self, sp: Span, forwards: bool) -> u32 {
-        let sp = sp.data();
-        if sp.lo == sp.hi {
-            debug!("find_width_of_character_at_span: early return empty span");
-            return 1;
-        }
-
-        let local_begin = self.lookup_byte_offset(sp.lo);
-        let local_end = self.lookup_byte_offset(sp.hi);
-        debug!("find_width_of_character_at_span: local_begin=`{:?}`, local_end=`{:?}`",
-               local_begin, local_end);
-
-        if local_begin.sf.start_pos != local_end.sf.start_pos {
-            debug!("find_width_of_character_at_span: begin and end are in different files");
-            return 1;
-        }
-
-        let start_index = local_begin.pos.to_usize();
-        let end_index = local_end.pos.to_usize();
-        debug!("find_width_of_character_at_span: start_index=`{:?}`, end_index=`{:?}`",
-               start_index, end_index);
-
-        // Disregard indexes that are at the start or end of their spans, they can't fit bigger
-        // characters.
-        if (!forwards && end_index == usize::min_value()) ||
-            (forwards && start_index == usize::max_value()) {
-            debug!("find_width_of_character_at_span: start or end of span, cannot be multibyte");
-            return 1;
-        }
-
-        let source_len = (local_begin.sf.end_pos - local_begin.sf.start_pos).to_usize();
-        debug!("find_width_of_character_at_span: source_len=`{:?}`", source_len);
-        // Ensure indexes are also not malformed.
-        if start_index > end_index || end_index > source_len {
-            debug!("find_width_of_character_at_span: source indexes are malformed");
-            return 1;
-        }
-
-        let src = local_begin.sf.external_src.borrow();
-
-        // We need to extend the snippet to the end of the src rather than to end_index so when
-        // searching forwards for boundaries we've got somewhere to search.
-        let snippet = if let Some(ref src) = local_begin.sf.src {
-            let len = src.len();
-            (&src[start_index..len])
-        } else if let Some(src) = src.get_source() {
-            let len = src.len();
-            (&src[start_index..len])
-        } else {
-            return 1;
-        };
-        debug!("find_width_of_character_at_span: snippet=`{:?}`", snippet);
-
-        let mut target = if forwards { end_index + 1 } else { end_index - 1 };
-        debug!("find_width_of_character_at_span: initial target=`{:?}`", target);
-
-        while !snippet.is_char_boundary(target - start_index) && target < source_len {
-            target = if forwards {
-                target + 1
-            } else {
-                match target.checked_sub(1) {
-                    Some(target) => target,
-                    None => {
-                        break;
-                    }
-                }
-            };
-            debug!("find_width_of_character_at_span: target=`{:?}`", target);
-        }
-        debug!("find_width_of_character_at_span: final target=`{:?}`", target);
-
-        if forwards {
-            (target - end_index) as u32
-        } else {
-            (end_index - target) as u32
-        }
-    }
-
-    pub fn get_source_file(&self, filename: &FileName) -> Option<Lrc<SourceFile>> {
-        for sf in self.files.borrow().source_files.iter() {
-            if *filename == sf.name {
-                return Some(sf.clone());
-            }
-        }
-        None
-    }
-
-    /// For a global `BytePos`, computes the local offset within the containing `SourceFile`.
-    pub fn lookup_byte_offset(&self, bpos: BytePos) -> SourceFileAndBytePos {
-        let idx = self.lookup_source_file_idx(bpos);
-        let sf = (*self.files.borrow().source_files)[idx].clone();
-        let offset = bpos - sf.start_pos;
-        SourceFileAndBytePos {sf, pos: offset}
-    }
-
-    /// Converts an absolute `BytePos` to a `CharPos` relative to the `SourceFile`.
-    pub fn bytepos_to_file_charpos(&self, bpos: BytePos) -> CharPos {
-        let idx = self.lookup_source_file_idx(bpos);
-        let map = &(*self.files.borrow().source_files)[idx];
-
-        // The number of extra bytes due to multibyte chars in the `SourceFile`.
-        let mut total_extra_bytes = 0;
-
-        for mbc in map.multibyte_chars.iter() {
-            debug!("{}-byte char at {:?}", mbc.bytes, mbc.pos);
-            if mbc.pos < bpos {
-                // Every character is at least one byte, so we only
-                // count the actual extra bytes.
-                total_extra_bytes += mbc.bytes as u32 - 1;
-                // We should never see a byte position in the middle of a
-                // character.
-                assert!(bpos.to_u32() >= mbc.pos.to_u32() + mbc.bytes as u32);
-            } else {
-                break;
-            }
-        }
-
-        assert!(map.start_pos.to_u32() + total_extra_bytes <= bpos.to_u32());
-        CharPos(bpos.to_usize() - map.start_pos.to_usize() - total_extra_bytes as usize)
-    }
-
-    // Returns the index of the `SourceFile` (in `self.files`) that contains `pos`.
-    pub fn lookup_source_file_idx(&self, pos: BytePos) -> usize {
-        self.files.borrow().source_files.binary_search_by_key(&pos, |key| key.start_pos)
-            .unwrap_or_else(|p| p - 1)
-    }
-
-    pub fn count_lines(&self) -> usize {
-        self.files().iter().fold(0, |a, f| a + f.count_lines())
-    }
-
-
-    pub fn generate_fn_name_span(&self, span: Span) -> Option<Span> {
-        let prev_span = self.span_extend_to_prev_str(span, "fn", true);
-        self.span_to_snippet(prev_span).map(|snippet| {
-            let len = snippet.find(|c: char| !c.is_alphanumeric() && c != '_')
-                .expect("no label after fn");
-            prev_span.with_hi(BytePos(prev_span.lo().0 + len as u32))
-        }).ok()
-    }
-
-    /// Takes the span of a type parameter in a function signature and try to generate a span for
-    /// the function name (with generics) and a new snippet for this span with the pointed type
-    /// parameter as a new local type parameter.
-    ///
-    /// For instance:
-    /// ```rust,ignore (pseudo-Rust)
-    /// // Given span
-    /// fn my_function(param: T)
-    /// //                    ^ Original span
-    ///
-    /// // Result
-    /// fn my_function(param: T)
-    /// // ^^^^^^^^^^^ Generated span with snippet `my_function<T>`
-    /// ```
-    ///
-    /// Attention: The method used is very fragile since it essentially duplicates the work of the
-    /// parser. If you need to use this function or something similar, please consider updating the
-    /// `SourceMap` functions and this function to something more robust.
-    pub fn generate_local_type_param_snippet(&self, span: Span) -> Option<(Span, String)> {
-        // Try to extend the span to the previous "fn" keyword to retrieve the function
-        // signature.
-        let sugg_span = self.span_extend_to_prev_str(span, "fn", false);
-        if sugg_span != span {
-            if let Ok(snippet) = self.span_to_snippet(sugg_span) {
-                // Consume the function name.
-                let mut offset = snippet.find(|c: char| !c.is_alphanumeric() && c != '_')
-                    .expect("no label after fn");
-
-                // Consume the generics part of the function signature.
-                let mut bracket_counter = 0;
-                let mut last_char = None;
-                for c in snippet[offset..].chars() {
-                    match c {
-                        '<' => bracket_counter += 1,
-                        '>' => bracket_counter -= 1,
-                        '(' => if bracket_counter == 0 { break; }
-                        _ => {}
-                    }
-                    offset += c.len_utf8();
-                    last_char = Some(c);
-                }
-
-                // Adjust the suggestion span to encompass the function name with its generics.
-                let sugg_span = sugg_span.with_hi(BytePos(sugg_span.lo().0 + offset as u32));
-
-                // Prepare the new suggested snippet to append the type parameter that triggered
-                // the error in the generics of the function signature.
-                let mut new_snippet = if last_char == Some('>') {
-                    format!("{}, ", &snippet[..(offset - '>'.len_utf8())])
-                } else {
-                    format!("{}<", &snippet[..offset])
-                };
-                new_snippet.push_str(
-                    &self.span_to_snippet(span).unwrap_or_else(|_| "T".to_string()));
-                new_snippet.push('>');
-
-                return Some((sugg_span, new_snippet));
-            }
-        }
-
-        None
-    }
-}
-
-impl SourceMapper for SourceMap {
-    fn lookup_char_pos(&self, pos: BytePos) -> Loc {
-        self.lookup_char_pos(pos)
-    }
-    fn span_to_lines(&self, sp: Span) -> FileLinesResult {
-        self.span_to_lines(sp)
-    }
-    fn span_to_string(&self, sp: Span) -> String {
-        self.span_to_string(sp)
-    }
-    fn span_to_snippet(&self, sp: Span) -> Result<String, SpanSnippetError> {
-        self.span_to_snippet(sp)
-    }
-    fn span_to_filename(&self, sp: Span) -> FileName {
-        self.span_to_filename(sp)
-    }
-    fn merge_spans(&self, sp_lhs: Span, sp_rhs: Span) -> Option<Span> {
-        self.merge_spans(sp_lhs, sp_rhs)
-    }
-    fn call_span_if_macro(&self, sp: Span) -> Span {
-        if self.span_to_filename(sp.clone()).is_macros() {
-            let v = sp.macro_backtrace();
-            if let Some(use_site) = v.last() {
-                return use_site.call_site;
-            }
-        }
-        sp
-    }
-    fn ensure_source_file_source_present(&self, source_file: Lrc<SourceFile>) -> bool {
-        source_file.add_external_src(
-            || match source_file.name {
-                FileName::Real(ref name) => self.file_loader.read_file(name).ok(),
-                _ => None,
-            }
-        )
-    }
-    fn doctest_offset_line(&self, file: &FileName, line: usize) -> usize {
-        self.doctest_offset_line(file, line)
-    }
-}
-
-#[derive(Clone)]
-pub struct FilePathMapping {
-    mapping: Vec<(PathBuf, PathBuf)>,
-}
-
-impl FilePathMapping {
-    pub fn empty() -> FilePathMapping {
-        FilePathMapping {
-            mapping: vec![]
-        }
-    }
-
-    pub fn new(mapping: Vec<(PathBuf, PathBuf)>) -> FilePathMapping {
-        FilePathMapping {
-            mapping,
-        }
-    }
-
-    /// Applies any path prefix substitution as defined by the mapping.
-    /// The return value is the remapped path and a boolean indicating whether
-    /// the path was affected by the mapping.
-    pub fn map_prefix(&self, path: PathBuf) -> (PathBuf, bool) {
-        // NOTE: We are iterating over the mapping entries from last to first
-        //       because entries specified later on the command line should
-        //       take precedence.
-        for &(ref from, ref to) in self.mapping.iter().rev() {
-            if let Ok(rest) = path.strip_prefix(from) {
-                return (to.join(rest), true);
-            }
-        }
-
-        (path, false)
-    }
-}
diff --git a/src/libsyntax/source_map/tests.rs b/src/libsyntax/source_map/tests.rs
deleted file mode 100644
index 15254336bbf..00000000000
--- a/src/libsyntax/source_map/tests.rs
+++ /dev/null
@@ -1,221 +0,0 @@
-use super::*;
-
-use rustc_data_structures::sync::Lrc;
-
-fn init_source_map() -> SourceMap {
-    let sm = SourceMap::new(FilePathMapping::empty());
-    sm.new_source_file(
-        PathBuf::from("blork.rs").into(),
-        "first line.\nsecond line".to_string(),
-    );
-    sm.new_source_file(
-        PathBuf::from("empty.rs").into(),
-        String::new(),
-    );
-    sm.new_source_file(
-        PathBuf::from("blork2.rs").into(),
-        "first line.\nsecond line".to_string(),
-    );
-    sm
-}
-
-/// Tests `lookup_byte_offset`.
-#[test]
-fn t3() {
-    let sm = init_source_map();
-
-    let srcfbp1 = sm.lookup_byte_offset(BytePos(23));
-    assert_eq!(srcfbp1.sf.name, PathBuf::from("blork.rs").into());
-    assert_eq!(srcfbp1.pos, BytePos(23));
-
-    let srcfbp1 = sm.lookup_byte_offset(BytePos(24));
-    assert_eq!(srcfbp1.sf.name, PathBuf::from("empty.rs").into());
-    assert_eq!(srcfbp1.pos, BytePos(0));
-
-    let srcfbp2 = sm.lookup_byte_offset(BytePos(25));
-    assert_eq!(srcfbp2.sf.name, PathBuf::from("blork2.rs").into());
-    assert_eq!(srcfbp2.pos, BytePos(0));
-}
-
-/// Tests `bytepos_to_file_charpos`.
-#[test]
-fn t4() {
-    let sm = init_source_map();
-
-    let cp1 = sm.bytepos_to_file_charpos(BytePos(22));
-    assert_eq!(cp1, CharPos(22));
-
-    let cp2 = sm.bytepos_to_file_charpos(BytePos(25));
-    assert_eq!(cp2, CharPos(0));
-}
-
-/// Tests zero-length `SourceFile`s.
-#[test]
-fn t5() {
-    let sm = init_source_map();
-
-    let loc1 = sm.lookup_char_pos(BytePos(22));
-    assert_eq!(loc1.file.name, PathBuf::from("blork.rs").into());
-    assert_eq!(loc1.line, 2);
-    assert_eq!(loc1.col, CharPos(10));
-
-    let loc2 = sm.lookup_char_pos(BytePos(25));
-    assert_eq!(loc2.file.name, PathBuf::from("blork2.rs").into());
-    assert_eq!(loc2.line, 1);
-    assert_eq!(loc2.col, CharPos(0));
-}
-
-fn init_source_map_mbc() -> SourceMap {
-    let sm = SourceMap::new(FilePathMapping::empty());
-    // "€" is a three-byte UTF8 char.
-    sm.new_source_file(PathBuf::from("blork.rs").into(),
-                    "fir€st €€€€ line.\nsecond line".to_string());
-    sm.new_source_file(PathBuf::from("blork2.rs").into(),
-                    "first line€€.\n€ second line".to_string());
-    sm
-}
-
-/// Tests `bytepos_to_file_charpos` in the presence of multi-byte chars.
-#[test]
-fn t6() {
-    let sm = init_source_map_mbc();
-
-    let cp1 = sm.bytepos_to_file_charpos(BytePos(3));
-    assert_eq!(cp1, CharPos(3));
-
-    let cp2 = sm.bytepos_to_file_charpos(BytePos(6));
-    assert_eq!(cp2, CharPos(4));
-
-    let cp3 = sm.bytepos_to_file_charpos(BytePos(56));
-    assert_eq!(cp3, CharPos(12));
-
-    let cp4 = sm.bytepos_to_file_charpos(BytePos(61));
-    assert_eq!(cp4, CharPos(15));
-}
-
-/// Test `span_to_lines` for a span ending at the end of a `SourceFile`.
-#[test]
-fn t7() {
-    let sm = init_source_map();
-    let span = Span::with_root_ctxt(BytePos(12), BytePos(23));
-    let file_lines = sm.span_to_lines(span).unwrap();
-
-    assert_eq!(file_lines.file.name, PathBuf::from("blork.rs").into());
-    assert_eq!(file_lines.lines.len(), 1);
-    assert_eq!(file_lines.lines[0].line_index, 1);
-}
-
-/// Given a string like " ~~~~~~~~~~~~ ", produces a span
-/// converting that range. The idea is that the string has the same
-/// length as the input, and we uncover the byte positions. Note
-/// that this can span lines and so on.
-fn span_from_selection(input: &str, selection: &str) -> Span {
-    assert_eq!(input.len(), selection.len());
-    let left_index = selection.find('~').unwrap() as u32;
-    let right_index = selection.rfind('~').map(|x|x as u32).unwrap_or(left_index);
-    Span::with_root_ctxt(BytePos(left_index), BytePos(right_index + 1))
-}
-
-/// Tests `span_to_snippet` and `span_to_lines` for a span converting 3
-/// lines in the middle of a file.
-#[test]
-fn span_to_snippet_and_lines_spanning_multiple_lines() {
-    let sm = SourceMap::new(FilePathMapping::empty());
-    let inputtext = "aaaaa\nbbbbBB\nCCC\nDDDDDddddd\neee\n";
-    let selection = "     \n    ~~\n~~~\n~~~~~     \n   \n";
-    sm.new_source_file(Path::new("blork.rs").to_owned().into(), inputtext.to_string());
-    let span = span_from_selection(inputtext, selection);
-
-    // Check that we are extracting the text we thought we were extracting.
-    assert_eq!(&sm.span_to_snippet(span).unwrap(), "BB\nCCC\nDDDDD");
-
-    // Check that span_to_lines gives us the complete result with the lines/cols we expected.
-    let lines = sm.span_to_lines(span).unwrap();
-    let expected = vec![
-        LineInfo { line_index: 1, start_col: CharPos(4), end_col: CharPos(6) },
-        LineInfo { line_index: 2, start_col: CharPos(0), end_col: CharPos(3) },
-        LineInfo { line_index: 3, start_col: CharPos(0), end_col: CharPos(5) }
-        ];
-    assert_eq!(lines.lines, expected);
-}
-
-/// Test span_to_snippet for a span ending at the end of a `SourceFile`.
-#[test]
-fn t8() {
-    let sm = init_source_map();
-    let span = Span::with_root_ctxt(BytePos(12), BytePos(23));
-    let snippet = sm.span_to_snippet(span);
-
-    assert_eq!(snippet, Ok("second line".to_string()));
-}
-
-/// Test `span_to_str` for a span ending at the end of a `SourceFile`.
-#[test]
-fn t9() {
-    let sm = init_source_map();
-    let span = Span::with_root_ctxt(BytePos(12), BytePos(23));
-    let sstr =  sm.span_to_string(span);
-
-    assert_eq!(sstr, "blork.rs:2:1: 2:12");
-}
-
-/// Tests failing to merge two spans on different lines.
-#[test]
-fn span_merging_fail() {
-    let sm = SourceMap::new(FilePathMapping::empty());
-    let inputtext  = "bbbb BB\ncc CCC\n";
-    let selection1 = "     ~~\n      \n";
-    let selection2 = "       \n   ~~~\n";
-    sm.new_source_file(Path::new("blork.rs").to_owned().into(), inputtext.to_owned());
-    let span1 = span_from_selection(inputtext, selection1);
-    let span2 = span_from_selection(inputtext, selection2);
-
-    assert!(sm.merge_spans(span1, span2).is_none());
-}
-
-/// Returns the span corresponding to the `n`th occurrence of `substring` in `source_text`.
-trait SourceMapExtension {
-    fn span_substr(
-        &self,
-        file: &Lrc<SourceFile>,
-        source_text: &str,
-        substring: &str,
-        n: usize,
-    ) -> Span;
-}
-
-impl SourceMapExtension for SourceMap {
-    fn span_substr(
-        &self,
-        file: &Lrc<SourceFile>,
-        source_text: &str,
-        substring: &str,
-        n: usize,
-    ) -> Span {
-        println!(
-            "span_substr(file={:?}/{:?}, substring={:?}, n={})",
-            file.name, file.start_pos, substring, n
-        );
-        let mut i = 0;
-        let mut hi = 0;
-        loop {
-            let offset = source_text[hi..].find(substring).unwrap_or_else(|| {
-                panic!(
-                    "source_text `{}` does not have {} occurrences of `{}`, only {}",
-                    source_text, n, substring, i
-                );
-            });
-            let lo = hi + offset;
-            hi = lo + substring.len();
-            if i == n {
-                let span = Span::with_root_ctxt(
-                    BytePos(lo as u32 + file.start_pos.0),
-                    BytePos(hi as u32 + file.start_pos.0),
-                );
-                assert_eq!(&self.span_to_snippet(span).unwrap()[..], substring);
-                return span;
-            }
-            i += 1;
-        }
-    }
-}
diff --git a/src/libsyntax/tests.rs b/src/libsyntax/tests.rs
deleted file mode 100644
index ed457c3627f..00000000000
--- a/src/libsyntax/tests.rs
+++ /dev/null
@@ -1,1255 +0,0 @@
-use crate::ast;
-use crate::parse::source_file_to_stream;
-use crate::parse::new_parser_from_source_str;
-use crate::parse::parser::Parser;
-use crate::sess::ParseSess;
-use crate::source_map::{SourceMap, FilePathMapping};
-use crate::tokenstream::TokenStream;
-use crate::with_default_globals;
-
-use errors::emitter::EmitterWriter;
-use errors::{PResult, Handler};
-use rustc_data_structures::sync::Lrc;
-use syntax_pos::{BytePos, Span, MultiSpan};
-
-use std::io;
-use std::io::prelude::*;
-use std::iter::Peekable;
-use std::path::{Path, PathBuf};
-use std::str;
-use std::sync::{Arc, Mutex};
-
-/// Map string to parser (via tts).
-fn string_to_parser(ps: &ParseSess, source_str: String) -> Parser<'_> {
-    new_parser_from_source_str(ps, PathBuf::from("bogofile").into(), source_str)
-}
-
-crate fn with_error_checking_parse<'a, T, F>(s: String, ps: &'a ParseSess, f: F) -> T where
-    F: FnOnce(&mut Parser<'a>) -> PResult<'a, T>,
-{
-    let mut p = string_to_parser(&ps, s);
-    let x = f(&mut p).unwrap();
-    p.sess.span_diagnostic.abort_if_errors();
-    x
-}
-
-/// Maps a string to tts, using a made-up filename.
-crate fn string_to_stream(source_str: String) -> TokenStream {
-    let ps = ParseSess::new(FilePathMapping::empty());
-    source_file_to_stream(
-        &ps,
-        ps.source_map().new_source_file(PathBuf::from("bogofile").into(),
-        source_str,
-    ), None).0
-}
-
-/// Parses a string, returns a crate.
-crate fn string_to_crate(source_str : String) -> ast::Crate {
-    let ps = ParseSess::new(FilePathMapping::empty());
-    with_error_checking_parse(source_str, &ps, |p| {
-        p.parse_crate_mod()
-    })
-}
-
-/// Does the given string match the pattern? whitespace in the first string
-/// may be deleted or replaced with other whitespace to match the pattern.
-/// This function is relatively Unicode-ignorant; fortunately, the careful design
-/// of UTF-8 mitigates this ignorance. It doesn't do NKF-normalization(?).
-crate fn matches_codepattern(a : &str, b : &str) -> bool {
-    let mut a_iter = a.chars().peekable();
-    let mut b_iter = b.chars().peekable();
-
-    loop {
-        let (a, b) = match (a_iter.peek(), b_iter.peek()) {
-            (None, None) => return true,
-            (None, _) => return false,
-            (Some(&a), None) => {
-                if rustc_lexer::is_whitespace(a) {
-                    break // Trailing whitespace check is out of loop for borrowck.
-                } else {
-                    return false
-                }
-            }
-            (Some(&a), Some(&b)) => (a, b)
-        };
-
-        if rustc_lexer::is_whitespace(a) && rustc_lexer::is_whitespace(b) {
-            // Skip whitespace for `a` and `b`.
-            scan_for_non_ws_or_end(&mut a_iter);
-            scan_for_non_ws_or_end(&mut b_iter);
-        } else if rustc_lexer::is_whitespace(a) {
-            // Skip whitespace for `a`.
-            scan_for_non_ws_or_end(&mut a_iter);
-        } else if a == b {
-            a_iter.next();
-            b_iter.next();
-        } else {
-            return false
-        }
-    }
-
-    // Check if a has *only* trailing whitespace.
-    a_iter.all(rustc_lexer::is_whitespace)
-}
-
-/// Advances the given peekable `Iterator` until it reaches a non-whitespace character.
-fn scan_for_non_ws_or_end<I: Iterator<Item = char>>(iter: &mut Peekable<I>) {
-    while iter.peek().copied().map(|c| rustc_lexer::is_whitespace(c)) == Some(true) {
-        iter.next();
-    }
-}
-
-/// Identifies a position in the text by the n'th occurrence of a string.
-struct Position {
-    string: &'static str,
-    count: usize,
-}
-
-struct SpanLabel {
-    start: Position,
-    end: Position,
-    label: &'static str,
-}
-
-crate struct Shared<T: Write> {
-    pub data: Arc<Mutex<T>>,
-}
-
-impl<T: Write> Write for Shared<T> {
-    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        self.data.lock().unwrap().write(buf)
-    }
-
-    fn flush(&mut self) -> io::Result<()> {
-        self.data.lock().unwrap().flush()
-    }
-}
-
-fn test_harness(file_text: &str, span_labels: Vec<SpanLabel>, expected_output: &str) {
-    with_default_globals(|| {
-        let output = Arc::new(Mutex::new(Vec::new()));
-
-        let source_map = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        source_map.new_source_file(Path::new("test.rs").to_owned().into(), file_text.to_owned());
-
-        let primary_span = make_span(&file_text, &span_labels[0].start, &span_labels[0].end);
-        let mut msp = MultiSpan::from_span(primary_span);
-        for span_label in span_labels {
-            let span = make_span(&file_text, &span_label.start, &span_label.end);
-            msp.push_span_label(span, span_label.label.to_string());
-            println!("span: {:?} label: {:?}", span, span_label.label);
-            println!("text: {:?}", source_map.span_to_snippet(span));
-        }
-
-        let emitter = EmitterWriter::new(
-            Box::new(Shared { data: output.clone() }),
-            Some(source_map.clone()),
-            false,
-            false,
-            false,
-            None,
-            false,
-        );
-        let handler = Handler::with_emitter(true, None, Box::new(emitter));
-        handler.span_err(msp, "foo");
-
-        assert!(expected_output.chars().next() == Some('\n'),
-                "expected output should begin with newline");
-        let expected_output = &expected_output[1..];
-
-        let bytes = output.lock().unwrap();
-        let actual_output = str::from_utf8(&bytes).unwrap();
-        println!("expected output:\n------\n{}------", expected_output);
-        println!("actual output:\n------\n{}------", actual_output);
-
-        assert!(expected_output == actual_output)
-    })
-}
-
-fn make_span(file_text: &str, start: &Position, end: &Position) -> Span {
-    let start = make_pos(file_text, start);
-    let end = make_pos(file_text, end) + end.string.len(); // just after matching thing ends
-    assert!(start <= end);
-    Span::with_root_ctxt(BytePos(start as u32), BytePos(end as u32))
-}
-
-fn make_pos(file_text: &str, pos: &Position) -> usize {
-    let mut remainder = file_text;
-    let mut offset = 0;
-    for _ in 0..pos.count {
-        if let Some(n) = remainder.find(&pos.string) {
-            offset += n;
-            remainder = &remainder[n + 1..];
-        } else {
-            panic!("failed to find {} instances of {:?} in {:?}",
-                   pos.count,
-                   pos.string,
-                   file_text);
-        }
-    }
-    offset
-}
-
-#[test]
-fn ends_on_col0() {
-    test_harness(r#"
-fn foo() {
-}
-"#,
-    vec![
-        SpanLabel {
-           start: Position {
-               string: "{",
-               count: 1,
-           },
-           end: Position {
-               string: "}",
-               count: 1,
-           },
-           label: "test",
-       },
-    ],
-    r#"
-error: foo
- --> test.rs:2:10
-  |
-2 |   fn foo() {
-  |  __________^
-3 | | }
-  | |_^ test
-
-"#);
-}
-
-#[test]
-fn ends_on_col2() {
-    test_harness(r#"
-fn foo() {
-
-
-  }
-"#,
-     vec![
-        SpanLabel {
-            start: Position {
-                string: "{",
-                count: 1,
-            },
-            end: Position {
-                string: "}",
-                count: 1,
-            },
-            label: "test",
-        },
-     ],
-     r#"
-error: foo
- --> test.rs:2:10
-  |
-2 |   fn foo() {
-  |  __________^
-3 | |
-4 | |
-5 | |   }
-  | |___^ test
-
-"#);
-}
-#[test]
-fn non_nested() {
-    test_harness(r#"
-fn foo() {
-  X0 Y0
-  X1 Y1
-  X2 Y2
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "X0",
-                count: 1,
-            },
-            end: Position {
-                string: "X2",
-                count: 1,
-            },
-            label: "`X` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "Y0",
-                count: 1,
-            },
-            end: Position {
-                string: "Y2",
-                count: 1,
-            },
-            label: "`Y` is a good letter too",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:3
-  |
-3 |      X0 Y0
-  |  ____^__-
-  | | ___|
-  | ||
-4 | ||   X1 Y1
-5 | ||   X2 Y2
-  | ||____^__- `Y` is a good letter too
-  |  |____|
-  |       `X` is a good letter
-
-"#);
-}
-
-#[test]
-fn nested() {
-    test_harness(r#"
-fn foo() {
-  X0 Y0
-  Y1 X1
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "X0",
-                count: 1,
-            },
-            end: Position {
-                string: "X1",
-                count: 1,
-            },
-            label: "`X` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "Y0",
-                count: 1,
-            },
-            end: Position {
-                string: "Y1",
-                count: 1,
-            },
-            label: "`Y` is a good letter too",
-        },
-    ],
-r#"
-error: foo
- --> test.rs:3:3
-  |
-3 |      X0 Y0
-  |  ____^__-
-  | | ___|
-  | ||
-4 | ||   Y1 X1
-  | ||____-__^ `X` is a good letter
-  | |_____|
-  |       `Y` is a good letter too
-
-"#);
-}
-
-#[test]
-fn different_overlap() {
-    test_harness(r#"
-fn foo() {
-  X0 Y0 Z0
-  X1 Y1 Z1
-  X2 Y2 Z2
-  X3 Y3 Z3
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "Y0",
-                count: 1,
-            },
-            end: Position {
-                string: "X2",
-                count: 1,
-            },
-            label: "`X` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "Z1",
-                count: 1,
-            },
-            end: Position {
-                string: "X3",
-                count: 1,
-            },
-            label: "`Y` is a good letter too",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:6
-  |
-3 |      X0 Y0 Z0
-  |   ______^
-4 |  |   X1 Y1 Z1
-  |  |_________-
-5 | ||   X2 Y2 Z2
-  | ||____^ `X` is a good letter
-6 | |    X3 Y3 Z3
-  | |_____- `Y` is a good letter too
-
-"#);
-}
-
-#[test]
-fn triple_overlap() {
-    test_harness(r#"
-fn foo() {
-  X0 Y0 Z0
-  X1 Y1 Z1
-  X2 Y2 Z2
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "X0",
-                count: 1,
-            },
-            end: Position {
-                string: "X2",
-                count: 1,
-            },
-            label: "`X` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "Y0",
-                count: 1,
-            },
-            end: Position {
-                string: "Y2",
-                count: 1,
-            },
-            label: "`Y` is a good letter too",
-        },
-        SpanLabel {
-            start: Position {
-                string: "Z0",
-                count: 1,
-            },
-            end: Position {
-                string: "Z2",
-                count: 1,
-            },
-            label: "`Z` label",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:3
-  |
-3 |       X0 Y0 Z0
-  |  _____^__-__-
-  | | ____|__|
-  | || ___|
-  | |||
-4 | |||   X1 Y1 Z1
-5 | |||   X2 Y2 Z2
-  | |||____^__-__- `Z` label
-  |  ||____|__|
-  |   |____|  `Y` is a good letter too
-  |        `X` is a good letter
-
-"#);
-}
-
-#[test]
-fn triple_exact_overlap() {
-    test_harness(r#"
-fn foo() {
-  X0 Y0 Z0
-  X1 Y1 Z1
-  X2 Y2 Z2
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "X0",
-                count: 1,
-            },
-            end: Position {
-                string: "X2",
-                count: 1,
-            },
-            label: "`X` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "X0",
-                count: 1,
-            },
-            end: Position {
-                string: "X2",
-                count: 1,
-            },
-            label: "`Y` is a good letter too",
-        },
-        SpanLabel {
-            start: Position {
-                string: "X0",
-                count: 1,
-            },
-            end: Position {
-                string: "X2",
-                count: 1,
-            },
-            label: "`Z` label",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:3
-  |
-3 | /   X0 Y0 Z0
-4 | |   X1 Y1 Z1
-5 | |   X2 Y2 Z2
-  | |    ^
-  | |    |
-  | |    `X` is a good letter
-  | |____`Y` is a good letter too
-  |      `Z` label
-
-"#);
-}
-
-#[test]
-fn minimum_depth() {
-    test_harness(r#"
-fn foo() {
-  X0 Y0 Z0
-  X1 Y1 Z1
-  X2 Y2 Z2
-  X3 Y3 Z3
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "Y0",
-                count: 1,
-            },
-            end: Position {
-                string: "X1",
-                count: 1,
-            },
-            label: "`X` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "Y1",
-                count: 1,
-            },
-            end: Position {
-                string: "Z2",
-                count: 1,
-            },
-            label: "`Y` is a good letter too",
-        },
-        SpanLabel {
-            start: Position {
-                string: "X2",
-                count: 1,
-            },
-            end: Position {
-                string: "Y3",
-                count: 1,
-            },
-            label: "`Z`",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:6
-  |
-3 |      X0 Y0 Z0
-  |   ______^
-4 |  |   X1 Y1 Z1
-  |  |____^_-
-  | ||____|
-  | |     `X` is a good letter
-5 | |    X2 Y2 Z2
-  | |____-______- `Y` is a good letter too
-  |  ____|
-  | |
-6 | |    X3 Y3 Z3
-  | |________- `Z`
-
-"#);
-}
-
-#[test]
-fn non_overlaping() {
-    test_harness(r#"
-fn foo() {
-  X0 Y0 Z0
-  X1 Y1 Z1
-  X2 Y2 Z2
-  X3 Y3 Z3
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "X0",
-                count: 1,
-            },
-            end: Position {
-                string: "X1",
-                count: 1,
-            },
-            label: "`X` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "Y2",
-                count: 1,
-            },
-            end: Position {
-                string: "Z3",
-                count: 1,
-            },
-            label: "`Y` is a good letter too",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:3
-  |
-3 | /   X0 Y0 Z0
-4 | |   X1 Y1 Z1
-  | |____^ `X` is a good letter
-5 |     X2 Y2 Z2
-  |  ______-
-6 | |   X3 Y3 Z3
-  | |__________- `Y` is a good letter too
-
-"#);
-}
-
-#[test]
-fn overlaping_start_and_end() {
-    test_harness(r#"
-fn foo() {
-  X0 Y0 Z0
-  X1 Y1 Z1
-  X2 Y2 Z2
-  X3 Y3 Z3
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "Y0",
-                count: 1,
-            },
-            end: Position {
-                string: "X1",
-                count: 1,
-            },
-            label: "`X` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "Z1",
-                count: 1,
-            },
-            end: Position {
-                string: "Z3",
-                count: 1,
-            },
-            label: "`Y` is a good letter too",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:6
-  |
-3 |      X0 Y0 Z0
-  |   ______^
-4 |  |   X1 Y1 Z1
-  |  |____^____-
-  | ||____|
-  | |     `X` is a good letter
-5 | |    X2 Y2 Z2
-6 | |    X3 Y3 Z3
-  | |___________- `Y` is a good letter too
-
-"#);
-}
-
-#[test]
-fn multiple_labels_primary_without_message() {
-    test_harness(r#"
-fn foo() {
-  a { b { c } d }
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "b",
-                count: 1,
-            },
-            end: Position {
-                string: "}",
-                count: 1,
-            },
-            label: "",
-        },
-        SpanLabel {
-            start: Position {
-                string: "a",
-                count: 1,
-            },
-            end: Position {
-                string: "d",
-                count: 1,
-            },
-            label: "`a` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "c",
-                count: 1,
-            },
-            end: Position {
-                string: "c",
-                count: 1,
-            },
-            label: "",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:7
-  |
-3 |   a { b { c } d }
-  |   ----^^^^-^^-- `a` is a good letter
-
-"#);
-}
-
-#[test]
-fn multiple_labels_secondary_without_message() {
-    test_harness(r#"
-fn foo() {
-  a { b { c } d }
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "a",
-                count: 1,
-            },
-            end: Position {
-                string: "d",
-                count: 1,
-            },
-            label: "`a` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "b",
-                count: 1,
-            },
-            end: Position {
-                string: "}",
-                count: 1,
-            },
-            label: "",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:3
-  |
-3 |   a { b { c } d }
-  |   ^^^^-------^^ `a` is a good letter
-
-"#);
-}
-
-#[test]
-fn multiple_labels_primary_without_message_2() {
-    test_harness(r#"
-fn foo() {
-  a { b { c } d }
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "b",
-                count: 1,
-            },
-            end: Position {
-                string: "}",
-                count: 1,
-            },
-            label: "`b` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "a",
-                count: 1,
-            },
-            end: Position {
-                string: "d",
-                count: 1,
-            },
-            label: "",
-        },
-        SpanLabel {
-            start: Position {
-                string: "c",
-                count: 1,
-            },
-            end: Position {
-                string: "c",
-                count: 1,
-            },
-            label: "",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:7
-  |
-3 |   a { b { c } d }
-  |   ----^^^^-^^--
-  |       |
-  |       `b` is a good letter
-
-"#);
-}
-
-#[test]
-fn multiple_labels_secondary_without_message_2() {
-    test_harness(r#"
-fn foo() {
-  a { b { c } d }
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "a",
-                count: 1,
-            },
-            end: Position {
-                string: "d",
-                count: 1,
-            },
-            label: "",
-        },
-        SpanLabel {
-            start: Position {
-                string: "b",
-                count: 1,
-            },
-            end: Position {
-                string: "}",
-                count: 1,
-            },
-            label: "`b` is a good letter",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:3
-  |
-3 |   a { b { c } d }
-  |   ^^^^-------^^
-  |       |
-  |       `b` is a good letter
-
-"#);
-}
-
-#[test]
-fn multiple_labels_secondary_without_message_3() {
-    test_harness(r#"
-fn foo() {
-  a  bc  d
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "a",
-                count: 1,
-            },
-            end: Position {
-                string: "b",
-                count: 1,
-            },
-            label: "`a` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "c",
-                count: 1,
-            },
-            end: Position {
-                string: "d",
-                count: 1,
-            },
-            label: "",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:3
-  |
-3 |   a  bc  d
-  |   ^^^^----
-  |   |
-  |   `a` is a good letter
-
-"#);
-}
-
-#[test]
-fn multiple_labels_without_message() {
-    test_harness(r#"
-fn foo() {
-  a { b { c } d }
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "a",
-                count: 1,
-            },
-            end: Position {
-                string: "d",
-                count: 1,
-            },
-            label: "",
-        },
-        SpanLabel {
-            start: Position {
-                string: "b",
-                count: 1,
-            },
-            end: Position {
-                string: "}",
-                count: 1,
-            },
-            label: "",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:3
-  |
-3 |   a { b { c } d }
-  |   ^^^^-------^^
-
-"#);
-}
-
-#[test]
-fn multiple_labels_without_message_2() {
-    test_harness(r#"
-fn foo() {
-  a { b { c } d }
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "b",
-                count: 1,
-            },
-            end: Position {
-                string: "}",
-                count: 1,
-            },
-            label: "",
-        },
-        SpanLabel {
-            start: Position {
-                string: "a",
-                count: 1,
-            },
-            end: Position {
-                string: "d",
-                count: 1,
-            },
-            label: "",
-        },
-        SpanLabel {
-            start: Position {
-                string: "c",
-                count: 1,
-            },
-            end: Position {
-                string: "c",
-                count: 1,
-            },
-            label: "",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:7
-  |
-3 |   a { b { c } d }
-  |   ----^^^^-^^--
-
-"#);
-}
-
-#[test]
-fn multiple_labels_with_message() {
-    test_harness(r#"
-fn foo() {
-  a { b { c } d }
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "a",
-                count: 1,
-            },
-            end: Position {
-                string: "d",
-                count: 1,
-            },
-            label: "`a` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "b",
-                count: 1,
-            },
-            end: Position {
-                string: "}",
-                count: 1,
-            },
-            label: "`b` is a good letter",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:3
-  |
-3 |   a { b { c } d }
-  |   ^^^^-------^^
-  |   |   |
-  |   |   `b` is a good letter
-  |   `a` is a good letter
-
-"#);
-}
-
-#[test]
-fn single_label_with_message() {
-    test_harness(r#"
-fn foo() {
-  a { b { c } d }
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "a",
-                count: 1,
-            },
-            end: Position {
-                string: "d",
-                count: 1,
-            },
-            label: "`a` is a good letter",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:3
-  |
-3 |   a { b { c } d }
-  |   ^^^^^^^^^^^^^ `a` is a good letter
-
-"#);
-}
-
-#[test]
-fn single_label_without_message() {
-    test_harness(r#"
-fn foo() {
-  a { b { c } d }
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "a",
-                count: 1,
-            },
-            end: Position {
-                string: "d",
-                count: 1,
-            },
-            label: "",
-        },
-    ],
-    r#"
-error: foo
- --> test.rs:3:3
-  |
-3 |   a { b { c } d }
-  |   ^^^^^^^^^^^^^
-
-"#);
-}
-
-#[test]
-fn long_snippet() {
-    test_harness(r#"
-fn foo() {
-  X0 Y0 Z0
-  X1 Y1 Z1
-1
-2
-3
-4
-5
-6
-7
-8
-9
-10
-  X2 Y2 Z2
-  X3 Y3 Z3
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "Y0",
-                count: 1,
-            },
-            end: Position {
-                string: "X1",
-                count: 1,
-            },
-            label: "`X` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "Z1",
-                count: 1,
-            },
-            end: Position {
-                string: "Z3",
-                count: 1,
-            },
-            label: "`Y` is a good letter too",
-        },
-    ],
-    r#"
-error: foo
-  --> test.rs:3:6
-   |
-3  |      X0 Y0 Z0
-   |   ______^
-4  |  |   X1 Y1 Z1
-   |  |____^____-
-   | ||____|
-   | |     `X` is a good letter
-5  | |  1
-6  | |  2
-7  | |  3
-...  |
-15 | |    X2 Y2 Z2
-16 | |    X3 Y3 Z3
-   | |___________- `Y` is a good letter too
-
-"#);
-}
-
-#[test]
-fn long_snippet_multiple_spans() {
-    test_harness(r#"
-fn foo() {
-  X0 Y0 Z0
-1
-2
-3
-  X1 Y1 Z1
-4
-5
-6
-  X2 Y2 Z2
-7
-8
-9
-10
-  X3 Y3 Z3
-}
-"#,
-    vec![
-        SpanLabel {
-            start: Position {
-                string: "Y0",
-                count: 1,
-            },
-            end: Position {
-                string: "Y3",
-                count: 1,
-            },
-            label: "`Y` is a good letter",
-        },
-        SpanLabel {
-            start: Position {
-                string: "Z1",
-                count: 1,
-            },
-            end: Position {
-                string: "Z2",
-                count: 1,
-            },
-            label: "`Z` is a good letter too",
-        },
-    ],
-    r#"
-error: foo
-  --> test.rs:3:6
-   |
-3  |      X0 Y0 Z0
-   |   ______^
-4  |  | 1
-5  |  | 2
-6  |  | 3
-7  |  |   X1 Y1 Z1
-   |  |_________-
-8  | || 4
-9  | || 5
-10 | || 6
-11 | ||   X2 Y2 Z2
-   | ||__________- `Z` is a good letter too
-...   |
-15 |  | 10
-16 |  |   X3 Y3 Z3
-   |  |_______^ `Y` is a good letter
-
-"#);
-}
diff --git a/src/libsyntax/token.rs b/src/libsyntax/token.rs
index 6f3da344ccf..6f45211ac5f 100644
--- a/src/libsyntax/token.rs
+++ b/src/libsyntax/token.rs
@@ -14,11 +14,12 @@ use syntax_pos::{self, Span, DUMMY_SP};
 
 use std::fmt;
 use std::mem;
-#[cfg(target_arch = "x86_64")]
-use rustc_data_structures::static_assert_size;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lrc;
+use rustc_macros::HashStable_Generic;
 
 #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
+#[derive(HashStable_Generic)]
 pub enum BinOpToken {
     Plus,
     Minus,
@@ -34,6 +35,7 @@ pub enum BinOpToken {
 
 /// A delimiter token.
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
+#[derive(HashStable_Generic)]
 pub enum DelimToken {
     /// A round parenthesis (i.e., `(` or `)`).
     Paren,
@@ -55,7 +57,7 @@ impl DelimToken {
     }
 }
 
-#[derive(Clone, Copy, PartialEq, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, Copy, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub enum LitKind {
     Bool, // AST only, must never appear in a `Token`
     Byte,
@@ -70,7 +72,7 @@ pub enum LitKind {
 }
 
 /// A literal token.
-#[derive(Clone, Copy, PartialEq, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, Copy, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub struct Lit {
     pub kind: LitKind,
     pub symbol: Symbol,
@@ -107,14 +109,14 @@ 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 +143,12 @@ 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 {
@@ -191,7 +193,7 @@ fn ident_can_begin_type(name: ast::Name, span: Span, is_raw: bool) -> bool {
     ].contains(&name)
 }
 
-#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub enum TokenKind {
     /* Expression-operator symbols. */
     Eq,
@@ -261,9 +263,9 @@ pub enum TokenKind {
 
 // `TokenKind` is used a lot. Make sure it doesn't unintentionally get bigger.
 #[cfg(target_arch = "x86_64")]
-static_assert_size!(TokenKind, 16);
+rustc_data_structures::static_assert_size!(TokenKind, 16);
 
-#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable_Generic)]
 pub struct Token {
     pub kind: TokenKind,
     pub span: Span,
@@ -276,7 +278,7 @@ 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 +293,7 @@ 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 +307,7 @@ 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 +316,7 @@ 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 +379,7 @@ 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 +391,7 @@ 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 +448,13 @@ 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 +471,7 @@ 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 +482,16 @@ 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 +501,23 @@ 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 +527,7 @@ 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 +539,7 @@ 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,
@@ -726,3 +728,11 @@ impl fmt::Debug for Nonterminal {
         }
     }
 }
+
+impl<CTX> HashStable<CTX> for Nonterminal
+    where CTX: crate::HashStableContext
+{
+    fn hash_stable(&self, _hcx: &mut CTX, _hasher: &mut StableHasher) {
+        panic!("interpolated tokens should not be present in the HIR")
+    }
+}
diff --git a/src/libsyntax/tokenstream.rs b/src/libsyntax/tokenstream.rs
index 6e1bb85ce1a..491b9a9ade4 100644
--- a/src/libsyntax/tokenstream.rs
+++ b/src/libsyntax/tokenstream.rs
@@ -16,16 +16,13 @@
 use crate::token::{self, DelimToken, Token, TokenKind};
 
 use syntax_pos::{Span, DUMMY_SP};
-#[cfg(target_arch = "x86_64")]
-use rustc_data_structures::static_assert_size;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_macros::HashStable_Generic;
 use rustc_data_structures::sync::Lrc;
 use smallvec::{SmallVec, smallvec};
 
 use std::{iter, mem};
 
-#[cfg(test)]
-mod tests;
-
 /// When the main rust parser encounters a syntax-extension invocation, it
 /// parses the arguments to the invocation as a token-tree. This is a very
 /// loose structure, such that all sorts of different AST-fragments can
@@ -38,7 +35,7 @@ mod tests;
 ///
 /// The RHS of an MBE macro is the only place `SubstNt`s are substituted.
 /// Nothing special happens to misnamed or misplaced `SubstNt`s.
-#[derive(Debug, Clone, PartialEq, RustcEncodable, RustcDecodable)]
+#[derive(Debug, Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable_Generic)]
 pub enum TokenTree {
     /// A single token
     Token(Token),
@@ -120,6 +117,16 @@ impl TokenTree {
     }
 }
 
+impl<CTX> HashStable<CTX> for TokenStream
+    where CTX: crate::HashStableContext
+{
+    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
+        for sub_tt in self.trees() {
+            sub_tt.hash_stable(hcx, hasher);
+        }
+    }
+}
+
 /// A `TokenStream` is an abstract sequence of tokens, organized into `TokenTree`s.
 ///
 /// The goal is for procedural macros to work with `TokenStream`s and `TokenTree`s
@@ -132,7 +139,7 @@ pub type TreeAndJoint = (TokenTree, IsJoint);
 
 // `TokenStream` is used a lot. Make sure it doesn't unintentionally get bigger.
 #[cfg(target_arch = "x86_64")]
-static_assert_size!(TokenStream, 8);
+rustc_data_structures::static_assert_size!(TokenStream, 8);
 
 #[derive(Clone, Copy, Debug, PartialEq, RustcEncodable, RustcDecodable)]
 pub enum IsJoint {
@@ -218,7 +225,15 @@ impl TokenStream {
         self.0.len()
     }
 
-    pub(crate) fn from_streams(mut streams: SmallVec<[TokenStream; 2]>) -> TokenStream {
+    pub fn span(&self) -> Option<Span> {
+        match &**self.0 {
+            [] => None,
+            [(tt, _)] => Some(tt.span()),
+            [(tt_start, _), .., (tt_end, _)] => Some(tt_start.span().to(tt_end.span())),
+        }
+    }
+
+    pub fn from_streams(mut streams: SmallVec<[TokenStream; 2]>) -> TokenStream {
         match streams.len() {
             0 => TokenStream::default(),
             1 => streams.pop().unwrap(),
@@ -449,7 +464,7 @@ impl Cursor {
     }
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, RustcEncodable, RustcDecodable)]
+#[derive(Debug, Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable_Generic)]
 pub struct DelimSpan {
     pub open: Span,
     pub close: Span,
diff --git a/src/libsyntax/tokenstream/tests.rs b/src/libsyntax/tokenstream/tests.rs
deleted file mode 100644
index 5017e5f5424..00000000000
--- a/src/libsyntax/tokenstream/tests.rs
+++ /dev/null
@@ -1,108 +0,0 @@
-use super::*;
-
-use crate::ast::Name;
-use crate::with_default_globals;
-use crate::tests::string_to_stream;
-use syntax_pos::{Span, BytePos};
-
-fn string_to_ts(string: &str) -> TokenStream {
-    string_to_stream(string.to_owned())
-}
-
-fn sp(a: u32, b: u32) -> Span {
-    Span::with_root_ctxt(BytePos(a), BytePos(b))
-}
-
-#[test]
-fn test_concat() {
-    with_default_globals(|| {
-        let test_res = string_to_ts("foo::bar::baz");
-        let test_fst = string_to_ts("foo::bar");
-        let test_snd = string_to_ts("::baz");
-        let eq_res = TokenStream::from_streams(smallvec![test_fst, test_snd]);
-        assert_eq!(test_res.trees().count(), 5);
-        assert_eq!(eq_res.trees().count(), 5);
-        assert_eq!(test_res.eq_unspanned(&eq_res), true);
-    })
-}
-
-#[test]
-fn test_to_from_bijection() {
-    with_default_globals(|| {
-        let test_start = string_to_ts("foo::bar(baz)");
-        let test_end = test_start.trees().collect();
-        assert_eq!(test_start, test_end)
-    })
-}
-
-#[test]
-fn test_eq_0() {
-    with_default_globals(|| {
-        let test_res = string_to_ts("foo");
-        let test_eqs = string_to_ts("foo");
-        assert_eq!(test_res, test_eqs)
-    })
-}
-
-#[test]
-fn test_eq_1() {
-    with_default_globals(|| {
-        let test_res = string_to_ts("::bar::baz");
-        let test_eqs = string_to_ts("::bar::baz");
-        assert_eq!(test_res, test_eqs)
-    })
-}
-
-#[test]
-fn test_eq_3() {
-    with_default_globals(|| {
-        let test_res = string_to_ts("");
-        let test_eqs = string_to_ts("");
-        assert_eq!(test_res, test_eqs)
-    })
-}
-
-#[test]
-fn test_diseq_0() {
-    with_default_globals(|| {
-        let test_res = string_to_ts("::bar::baz");
-        let test_eqs = string_to_ts("bar::baz");
-        assert_eq!(test_res == test_eqs, false)
-    })
-}
-
-#[test]
-fn test_diseq_1() {
-    with_default_globals(|| {
-        let test_res = string_to_ts("(bar,baz)");
-        let test_eqs = string_to_ts("bar,baz");
-        assert_eq!(test_res == test_eqs, false)
-    })
-}
-
-#[test]
-fn test_is_empty() {
-    with_default_globals(|| {
-        let test0: TokenStream = Vec::<TokenTree>::new().into_iter().collect();
-        let test1: TokenStream =
-            TokenTree::token(token::Ident(Name::intern("a"), false), sp(0, 1)).into();
-        let test2 = string_to_ts("foo(bar::baz)");
-
-        assert_eq!(test0.is_empty(), true);
-        assert_eq!(test1.is_empty(), false);
-        assert_eq!(test2.is_empty(), false);
-    })
-}
-
-#[test]
-fn test_dotdotdot() {
-    with_default_globals(|| {
-        let mut builder = TokenStreamBuilder::new();
-        builder.push(TokenTree::token(token::Dot, sp(0, 1)).joint());
-        builder.push(TokenTree::token(token::Dot, sp(1, 2)).joint());
-        builder.push(TokenTree::token(token::Dot, sp(2, 3)));
-        let stream = builder.build();
-        assert!(stream.eq_unspanned(&string_to_ts("...")));
-        assert_eq!(stream.trees().count(), 1);
-    })
-}
diff --git a/src/libsyntax/util/comments.rs b/src/libsyntax/util/comments.rs
index 448b4f3b825..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;
@@ -47,7 +47,8 @@ crate fn is_block_doc_comment(s: &str) -> bool {
     res
 }
 
-crate fn is_doc_comment(s: &str) -> bool {
+// FIXME(#64197): Try to privatize this again.
+pub fn is_doc_comment(s: &str) -> bool {
     (s.starts_with("///") && is_line_doc_comment(s)) || s.starts_with("//!") ||
     (s.starts_with("/**") && is_block_doc_comment(s)) || s.starts_with("/*!")
 }
diff --git a/src/libsyntax/util/lev_distance.rs b/src/libsyntax/util/lev_distance.rs
index 4127a8c7fce..efb3c2396c3 100644
--- a/src/libsyntax/util/lev_distance.rs
+++ b/src/libsyntax/util/lev_distance.rs
@@ -77,6 +77,6 @@ pub fn find_best_match_for_name<'a, T>(iter_names: T,
     if let Some(candidate) = case_insensitive_match {
         Some(candidate) // exact case insensitive match has a higher priority
     } else {
-        if let Some((candidate, _)) = levenstein_match { Some(candidate) } else { None }
+        levenstein_match.map(|(candidate, _)| candidate)
     }
 }
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/visit.rs b/src/libsyntax/visit.rs
index ea2dc357e6e..4ee09b4b87a 100644
--- a/src/libsyntax/visit.rs
+++ b/src/libsyntax/visit.rs
@@ -263,10 +263,6 @@ pub fn walk_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a Item) {
             visitor.visit_ty(typ);
             visitor.visit_generics(generics)
         }
-        ItemKind::OpaqueTy(ref bounds, ref generics) => {
-            walk_list!(visitor, visit_param_bound, bounds);
-            visitor.visit_generics(generics)
-        }
         ItemKind::Enum(ref enum_definition, ref generics) => {
             visitor.visit_generics(generics);
             visitor.visit_enum_def(enum_definition, generics, item.id, item.span)
@@ -314,6 +310,7 @@ pub fn walk_variant<'a, V: Visitor<'a>>(visitor: &mut V, variant: &'a Variant)
     where V: Visitor<'a>,
 {
     visitor.visit_ident(variant.ident);
+    visitor.visit_vis(&variant.vis);
     visitor.visit_variant_data(&variant.data);
     walk_list!(visitor, visit_anon_const, &variant.disr_expr);
     walk_list!(visitor, visit_attribute, &variant.attrs);
@@ -585,6 +582,7 @@ pub fn walk_fn<'a, V>(visitor: &mut V, kind: FnKind<'a>, declaration: &'a FnDecl
 }
 
 pub fn walk_trait_item<'a, V: Visitor<'a>>(visitor: &mut V, trait_item: &'a TraitItem) {
+    visitor.visit_vis(&trait_item.vis);
     visitor.visit_ident(trait_item.ident);
     walk_list!(visitor, visit_attribute, &trait_item.attrs);
     visitor.visit_generics(&trait_item.generics);
@@ -628,9 +626,6 @@ pub fn walk_impl_item<'a, V: Visitor<'a>>(visitor: &mut V, impl_item: &'a ImplIt
         ImplItemKind::TyAlias(ref ty) => {
             visitor.visit_ty(ty);
         }
-        ImplItemKind::OpaqueTy(ref bounds) => {
-            walk_list!(visitor, visit_param_bound, bounds);
-        }
         ImplItemKind::Macro(ref mac) => {
             visitor.visit_mac(mac);
         }
@@ -713,7 +708,7 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
             visitor.visit_expr(left_expression);
             visitor.visit_expr(right_expression)
         }
-        ExprKind::AddrOf(_, ref subexpression) | ExprKind::Unary(_, ref subexpression) => {
+        ExprKind::AddrOf(_, _, ref subexpression) | ExprKind::Unary(_, ref subexpression) => {
             visitor.visit_expr(subexpression)
         }
         ExprKind::Cast(ref subexpression, ref typ) | ExprKind::Type(ref subexpression, ref typ) => {
@@ -846,11 +841,19 @@ 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) {
     match attr.kind {
-        AttrKind::Normal(ref item) => visitor.visit_tts(item.tokens.clone()),
+        AttrKind::Normal(ref item) => walk_mac_args(visitor, &item.args),
         AttrKind::DocComment(_) => {}
     }
 }
 
+pub fn walk_mac_args<'a, V: Visitor<'a>>(visitor: &mut V, args: &'a MacArgs) {
+    match args {
+        MacArgs::Empty => {}
+        MacArgs::Delimited(_dspan, _delim, tokens) => visitor.visit_tts(tokens.clone()),
+        MacArgs::Eq(_eq_span, tokens) => visitor.visit_tts(tokens.clone()),
+    }
+}
+
 pub fn walk_tt<'a, V: Visitor<'a>>(visitor: &mut V, tt: TokenTree) {
     match tt {
         TokenTree::Token(token) => visitor.visit_token(token),