Merge pull request #1 from rust-lang/master

Pull from newest repo

1 files changed, 433 insertions, 7278 deletions

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 24d120376de..89725d8b339 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -1,75 +1,40 @@
-// ignore-tidy-filelength
-
-use crate::ast::{AngleBracketedArgs, AsyncArgument, ParenthesizedArgs, AttrStyle, BareFnTy};
-use crate::ast::{GenericBound, TraitBoundModifier};
-use crate::ast::Unsafety;
-use crate::ast::{Mod, AnonConst, Arg, ArgSource, Arm, Guard, Attribute, BindingMode, TraitItemKind};
-use crate::ast::Block;
-use crate::ast::{BlockCheckMode, CaptureBy, Movability};
-use crate::ast::{Constness, Crate};
-use crate::ast::Defaultness;
-use crate::ast::EnumDef;
-use crate::ast::{Expr, ExprKind, RangeLimits};
-use crate::ast::{Field, FnDecl, FnHeader};
-use crate::ast::{ForeignItem, ForeignItemKind, FunctionRetTy};
-use crate::ast::{GenericParam, GenericParamKind};
-use crate::ast::GenericArg;
-use crate::ast::{Ident, ImplItem, IsAsync, IsAuto, Item, ItemKind};
-use crate::ast::{Label, Lifetime};
-use crate::ast::{Local, LocalSource};
-use crate::ast::MacStmtStyle;
-use crate::ast::{Mac, Mac_, MacDelimiter};
-use crate::ast::{MutTy, Mutability};
-use crate::ast::{Pat, PatKind, PathSegment};
-use crate::ast::{PolyTraitRef, QSelf};
-use crate::ast::{Stmt, StmtKind};
-use crate::ast::{VariantData, StructField};
-use crate::ast::StrStyle;
-use crate::ast::SelfKind;
-use crate::ast::{TraitItem, TraitRef, TraitObjectSyntax};
-use crate::ast::{Ty, TyKind, TypeBinding, GenericBounds};
-use crate::ast::{Visibility, VisibilityKind, WhereClause, CrateSugar};
-use crate::ast::{UseTree, UseTreeKind};
-use crate::ast::{BinOpKind, UnOp};
-use crate::ast::{RangeEnd, RangeSyntax};
-use crate::{ast, attr};
-use crate::ext::base::DummyResult;
-use crate::source_map::{self, SourceMap, Spanned, respan};
-use crate::parse::{SeqSep, classify, literal, token};
-use crate::parse::lexer::{TokenAndSpan, UnmatchedBrace};
+mod expr;
+mod pat;
+mod item;
+pub use item::AliasKind;
+mod module;
+pub use module::{ModulePath, ModulePathSuccess};
+mod ty;
+mod path;
+pub use path::PathStyle;
+mod stmt;
+mod generics;
+
+use crate::ast::{self, AttrStyle, Attribute, Arg, BindingMode, StrStyle, SelfKind};
+use crate::ast::{FnDecl, Ident, IsAsync, MacDelimiter, Mutability, TyKind};
+use crate::ast::{Visibility, VisibilityKind, Unsafety, CrateSugar};
+use crate::source_map::{self, respan};
+use crate::parse::{SeqSep, literal, token};
+use crate::parse::lexer::UnmatchedBrace;
 use crate::parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
-use crate::parse::token::DelimToken;
-use crate::parse::{new_sub_parser_from_file, ParseSess, Directory, DirectoryOwnership};
-use crate::util::parser::{AssocOp, Fixity};
+use crate::parse::token::{Token, TokenKind, DelimToken};
+use crate::parse::{ParseSess, Directory, DirectoryOwnership};
 use crate::print::pprust;
 use crate::ptr::P;
 use crate::parse::PResult;
 use crate::ThinVec;
 use crate::tokenstream::{self, DelimSpan, TokenTree, TokenStream, TreeAndJoint};
-use crate::symbol::{keywords, sym, Symbol};
+use crate::symbol::{kw, sym, Symbol};
+use crate::parse::diagnostics::{Error, dummy_arg};
 
-use errors::{Applicability, DiagnosticBuilder, DiagnosticId, FatalError};
+use errors::{Applicability, DiagnosticId, FatalError};
 use rustc_target::spec::abi::{self, Abi};
-use syntax_pos::{
-    Span, MultiSpan, BytePos, FileName,
-    hygiene::CompilerDesugaringKind,
-};
-use log::{debug, trace};
+use syntax_pos::{Span, BytePos, DUMMY_SP, FileName};
+use log::debug;
 
 use std::borrow::Cow;
-use std::cmp;
-use std::mem;
-use std::path::{self, Path, PathBuf};
-use std::slice;
-
-#[derive(Debug)]
-/// Whether the type alias or associated type is a concrete type or an existential type
-pub 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
-    Existential(GenericBounds),
-}
+use std::{cmp, mem, slice};
+use std::path::PathBuf;
 
 bitflags::bitflags! {
     struct Restrictions: u8 {
@@ -78,31 +43,6 @@ bitflags::bitflags! {
     }
 }
 
-type ItemInfo = (Ident, ItemKind, Option<Vec<Attribute>>);
-
-/// 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,
-}
-
 #[derive(Clone, Copy, PartialEq, Debug)]
 crate enum SemiColonMode {
     Break,
@@ -116,40 +56,11 @@ crate enum BlockMode {
     Ignore,
 }
 
-/// 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 {
-            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.span, ExprKind::Path(None, path), ThinVec::new()));
-                }
-                token::NtBlock(block) => {
-                    let block = block.clone();
-                    $p.bump();
-                    return Ok($p.mk_expr($p.span, ExprKind::Block(block, None), ThinVec::new()));
-                }
-                _ => {},
-            };
-        }
-    }
-}
-
 /// As maybe_whole_expr, but for things other than expressions
+#[macro_export]
 macro_rules! maybe_whole {
     ($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
-        if let token::Interpolated(nt) = &$p.token {
+        if let token::Interpolated(nt) = &$p.token.kind {
             if let token::$constructor(x) = &**nt {
                 let $x = x.clone();
                 $p.bump();
@@ -160,10 +71,11 @@ macro_rules! maybe_whole {
 }
 
 /// 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 {
+            if let token::Interpolated(nt) = &$self.token.kind {
                 if let token::NtTy(ty) = &**nt {
                     let ty = ty.clone();
                     $self.bump();
@@ -193,33 +105,36 @@ enum PrevTokenKind {
     Other,
 }
 
-/* ident is handled by common.rs */
+// NOTE: `Ident`s are handled by `common.rs`.
 
 #[derive(Clone)]
 pub struct Parser<'a> {
     pub sess: &'a ParseSess,
-    /// the current token:
-    pub token: token::Token,
-    /// the span of the current token:
-    pub span: Span,
-    /// the span of the previous token:
+    /// 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,
+    /// Span of the current non-normalized token.
     meta_var_span: Option<Span>,
+    /// Span of the previous non-normalized token.
     pub prev_span: Span,
-    /// the previous token kind
+    /// 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
+    /// Used to determine the path to externally loaded source files.
     crate directory: Directory<'a>,
-    /// Whether to parse sub-modules in other files.
+    /// `true` to parse sub-modules in other files.
     pub 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>,
     crate expected_tokens: Vec<TokenType>,
-    token_cursor: TokenCursor,
+    crate token_cursor: TokenCursor,
     desugar_doc_comments: bool,
-    /// Whether we should configure out of line modules as we parse.
+    /// `true` we should configure out of line modules as we parse.
     pub 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
@@ -232,7 +147,10 @@ pub struct Parser<'a> {
     /// it gets removed from here. Every entry left at the end gets emitted as an independent
     /// error.
     crate unclosed_delims: Vec<UnmatchedBrace>,
-    last_unexpected_token_span: Option<Span>,
+    crate last_unexpected_token_span: Option<Span>,
+    crate last_type_ascription: Option<(Span, bool /* likely path typo */)>,
+    /// If present, this `Parser` is not parsing Rust code but rather a macro call.
+    crate subparser_name: Option<&'static str>,
 }
 
 impl<'a> Drop for Parser<'a> {
@@ -243,19 +161,19 @@ impl<'a> Drop for Parser<'a> {
 }
 
 #[derive(Clone)]
-struct TokenCursor {
-    frame: TokenCursorFrame,
-    stack: Vec<TokenCursorFrame>,
+crate struct TokenCursor {
+    crate frame: TokenCursorFrame,
+    crate 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,
+crate struct TokenCursorFrame {
+    crate delim: token::DelimToken,
+    crate span: DelimSpan,
+    crate open_delim: bool,
+    crate tree_cursor: tokenstream::Cursor,
+    crate close_delim: bool,
+    crate last_token: LastToken,
 }
 
 /// This is used in `TokenCursorFrame` above to track tokens that are consumed
@@ -276,16 +194,16 @@ struct TokenCursorFrame {
 /// You can find some more example usage of this in the `collect_tokens` method
 /// on the parser.
 #[derive(Clone)]
-enum LastToken {
+crate enum LastToken {
     Collecting(Vec<TreeAndJoint>),
     Was(Option<TreeAndJoint>),
 }
 
 impl TokenCursorFrame {
-    fn new(sp: DelimSpan, delim: DelimToken, tts: &TokenStream) -> Self {
+    fn new(span: DelimSpan, delim: DelimToken, tts: &TokenStream) -> Self {
         TokenCursorFrame {
-            delim: delim,
-            span: sp,
+            delim,
+            span,
             open_delim: delim == token::NoDelim,
             tree_cursor: tts.clone().into_trees(),
             close_delim: delim == token::NoDelim,
@@ -295,7 +213,7 @@ impl TokenCursorFrame {
 }
 
 impl TokenCursor {
-    fn next(&mut self) -> TokenAndSpan {
+    fn next(&mut self) -> Token {
         loop {
             let tree = if !self.frame.open_delim {
                 self.frame.open_delim = true;
@@ -309,7 +227,7 @@ impl TokenCursor {
                 self.frame = frame;
                 continue
             } else {
-                return TokenAndSpan { tok: token::Eof, sp: syntax_pos::DUMMY_SP }
+                return Token::new(token::Eof, DUMMY_SP);
             };
 
             match self.frame.last_token {
@@ -318,7 +236,7 @@ impl TokenCursor {
             }
 
             match tree {
-                TokenTree::Token(sp, tok) => return TokenAndSpan { tok: tok, sp: sp },
+                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));
@@ -327,9 +245,9 @@ impl TokenCursor {
         }
     }
 
-    fn next_desugared(&mut self) -> TokenAndSpan {
-        let (sp, name) = match self.next() {
-            TokenAndSpan { sp, tok: token::DocComment(name) } => (sp, name),
+    fn next_desugared(&mut self) -> Token {
+        let (name, sp) = match self.next() {
+            Token { kind: token::DocComment(name), span } => (name, span),
             tok => return tok,
         };
 
@@ -352,10 +270,12 @@ impl TokenCursor {
         let body = TokenTree::Delimited(
             delim_span,
             token::Bracket,
-            [TokenTree::Token(sp, token::Ident(ast::Ident::with_empty_ctxt(sym::doc), false)),
-             TokenTree::Token(sp, token::Eq),
-             TokenTree::Token(sp, token::Literal(
-                token::StrRaw(Symbol::intern(&stripped), num_of_hashes), None))
+            [
+                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(),
         );
@@ -364,10 +284,10 @@ impl TokenCursor {
             delim_span,
             token::NoDelim,
             &if doc_comment_style(&name.as_str()) == AttrStyle::Inner {
-                [TokenTree::Token(sp, token::Pound), TokenTree::Token(sp, token::Not), body]
+                [TokenTree::token(token::Pound, sp), TokenTree::token(token::Not, sp), body]
                     .iter().cloned().collect::<TokenStream>().into()
             } else {
-                [TokenTree::Token(sp, token::Pound), body]
+                [TokenTree::token(token::Pound, sp), body]
                     .iter().cloned().collect::<TokenStream>().into()
             },
         )));
@@ -378,8 +298,8 @@ impl TokenCursor {
 
 #[derive(Clone, PartialEq)]
 crate enum TokenType {
-    Token(token::Token),
-    Keyword(keywords::Keyword),
+    Token(TokenKind),
+    Keyword(Symbol),
     Operator,
     Lifetime,
     Ident,
@@ -391,8 +311,8 @@ crate enum TokenType {
 impl TokenType {
     crate fn to_string(&self) -> String {
         match *self {
-            TokenType::Token(ref t) => format!("`{}`", pprust::token_to_string(t)),
-            TokenType::Keyword(kw) => format!("`{}`", kw.name()),
+            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(),
@@ -403,145 +323,25 @@ impl TokenType {
     }
 }
 
-/// 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::Token) -> bool {
-    t == &token::ModSep || t == &token::Lt ||
-    t == &token::BinOp(token::Shl)
-}
-
-/// Information about the path to a module.
-pub struct ModulePath {
-    name: String,
-    path_exists: bool,
-    pub result: Result<ModulePathSuccess, Error>,
-}
-
-pub struct ModulePathSuccess {
-    pub path: PathBuf,
-    pub directory_ownership: DirectoryOwnership,
-    warn: bool,
-}
-
-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
-            }
-        }
-    }
-}
-
-#[derive(Debug)]
-enum LhsExpr {
-    NotYetParsed,
-    AttributesParsed(ThinVec<Attribute>),
-    AlreadyParsed(P<Expr>),
-}
-
-impl From<Option<ThinVec<Attribute>>> for LhsExpr {
-    fn from(o: Option<ThinVec<Attribute>>) -> Self {
-        if let Some(attrs) = o {
-            LhsExpr::AttributesParsed(attrs)
-        } else {
-            LhsExpr::NotYetParsed
-        }
-    }
-}
-
-impl From<P<Expr>> for LhsExpr {
-    fn from(expr: P<Expr>) -> Self {
-        LhsExpr::AlreadyParsed(expr)
-    }
-}
-
-/// Creates a placeholder argument.
-fn dummy_arg(span: Span) -> Arg {
-    let ident = Ident::new(keywords::Invalid.name(), span);
-    let pat = P(Pat {
-        id: ast::DUMMY_NODE_ID,
-        node: PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), ident, None),
-        span,
-    });
-    let ty = Ty {
-        node: TyKind::Err,
-        span,
-        id: ast::DUMMY_NODE_ID
-    };
-    Arg { ty: P(ty), pat: pat, id: ast::DUMMY_NODE_ID, source: ast::ArgSource::Normal }
-}
-
 #[derive(Copy, Clone, Debug)]
-enum TokenExpectType {
+crate enum TokenExpectType {
     Expect,
     NoExpect,
 }
 
 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)
-               -> Self {
+    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::Whitespace,
-            span: syntax_pos::DUMMY_SP,
-            prev_span: syntax_pos::DUMMY_SP,
+            token: Token::dummy(),
+            prev_span: DUMMY_SP,
             meta_var_span: None,
             prev_token_kind: PrevTokenKind::Other,
             restrictions: Restrictions::empty(),
@@ -566,16 +366,17 @@ impl<'a> Parser<'a> {
             max_angle_bracket_count: 0,
             unclosed_delims: Vec::new(),
             last_unexpected_token_span: None,
+            last_type_ascription: None,
+            subparser_name,
         };
 
-        let tok = parser.next_tok();
-        parser.token = tok.tok;
-        parser.span = tok.sp;
+        parser.token = parser.next_tok();
 
         if let Some(directory) = directory {
             parser.directory = directory;
-        } else if !parser.span.is_dummy() {
-            if let FileName::Real(mut path) = sess.source_map().span_to_unmapped_path(parser.span) {
+        } else if !parser.token.span.is_dummy() {
+            if let FileName::Real(mut path) =
+                    sess.source_map().span_to_unmapped_path(parser.token.span) {
                 path.pop();
                 parser.directory.path = Cow::from(path);
             }
@@ -585,15 +386,15 @@ impl<'a> Parser<'a> {
         parser
     }
 
-    fn next_tok(&mut self) -> TokenAndSpan {
+    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.sp.is_dummy() {
+        if next.span.is_dummy() {
             // Tweak the location for better diagnostics, but keep syntactic context intact.
-            next.sp = self.prev_span.with_ctxt(next.sp.ctxt());
+            next.span = self.prev_span.with_ctxt(next.span.ctxt());
         }
         next
     }
@@ -603,11 +404,11 @@ impl<'a> Parser<'a> {
         pprust::token_to_string(&self.token)
     }
 
-    fn token_descr(&self) -> Option<&'static str> {
-        Some(match &self.token {
-            t if t.is_special_ident() => "reserved identifier",
-            t if t.is_used_keyword() => "keyword",
-            t if t.is_unused_keyword() => "reserved keyword",
+    crate 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,
         })
@@ -629,44 +430,13 @@ impl<'a> Parser<'a> {
     }
 
     /// Expects and consumes the token `t`. Signals an error if the next token is not `t`.
-    pub fn expect(&mut self, t: &token::Token) -> PResult<'a,  bool /* recovered */> {
+    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 {
-                let token_str = pprust::token_to_string(t);
-                let this_token_str = self.this_token_descr();
-                let mut err = self.fatal(&format!("expected `{}`, found {}",
-                                                  token_str,
-                                                  this_token_str));
-
-                let sp = if self.token == token::Token::Eof {
-                    // EOF, don't want to point at the following char, but rather the last token
-                    self.prev_span
-                } else {
-                    self.sess.source_map().next_point(self.prev_span)
-                };
-                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 cm = self.sess.source_map();
-                match (cm.lookup_line(self.span.lo()), cm.lookup_line(sp.lo())) {
-                    (Ok(ref a), Ok(ref b)) if a.line == b.line => {
-                        // 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(self.span, label_exp);
-                    }
-                    _ => {
-                        err.span_label(sp, label_exp);
-                        err.span_label(self.span, "unexpected token");
-                    }
-                }
-                Err(err)
+                self.unexpected_try_recover(t)
             }
         } else {
             self.expect_one_of(slice::from_ref(t), &[])
@@ -678,193 +448,20 @@ impl<'a> Parser<'a> {
     /// anything.  Signal a fatal error if next token is unexpected.
     pub fn expect_one_of(
         &mut self,
-        edible: &[token::Token],
-        inedible: &[token::Token],
+        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
-            })
-        }
-        if edible.contains(&self.token) {
+        if edible.contains(&self.token.kind) {
             self.bump();
             Ok(false)
-        } else if inedible.contains(&self.token) {
+        } else if inedible.contains(&self.token.kind) {
             // leave it in the input
             Ok(false)
-        } else if self.last_unexpected_token_span == Some(self.span) {
+        } else if self.last_unexpected_token_span == Some(self.token.span) {
             FatalError.raise();
         } else {
-            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_to_string();
-            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 {} here", 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 {} here", expect)))
-            };
-            self.last_unexpected_token_span = Some(self.span);
-            let mut err = self.fatal(&msg_exp);
-            if self.token.is_ident_named("and") {
-                err.span_suggestion_short(
-                    self.span,
-                    "use `&&` instead of `and` for the boolean operator",
-                    "&&".to_string(),
-                    Applicability::MaybeIncorrect,
-                );
-            }
-            if self.token.is_ident_named("or") {
-                err.span_suggestion_short(
-                    self.span,
-                    "use `||` instead of `or` for the boolean operator",
-                    "||".to_string(),
-                    Applicability::MaybeIncorrect,
-                );
-            }
-            let sp = if self.token == 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 is_semi_suggestable = expected.iter().any(|t| match t {
-                TokenType::Token(token::Semi) => true, // we expect a `;` here
-                _ => false,
-            }) && ( // a `;` would be expected before the current keyword
-                self.token.is_keyword(keywords::Break) ||
-                self.token.is_keyword(keywords::Continue) ||
-                self.token.is_keyword(keywords::For) ||
-                self.token.is_keyword(keywords::If) ||
-                self.token.is_keyword(keywords::Let) ||
-                self.token.is_keyword(keywords::Loop) ||
-                self.token.is_keyword(keywords::Match) ||
-                self.token.is_keyword(keywords::Return) ||
-                self.token.is_keyword(keywords::While)
-            );
-            let cm = self.sess.source_map();
-            match (cm.lookup_line(self.span.lo()), cm.lookup_line(sp.lo())) {
-                (Ok(ref a), Ok(ref b)) if a.line != b.line && is_semi_suggestable => {
-                    // The spans are in different lines, expected `;` and found `let` or `return`.
-                    // High likelihood that it is only a missing `;`.
-                    err.span_suggestion_short(
-                        label_sp,
-                        "a semicolon may be missing here",
-                        ";".to_string(),
-                        Applicability::MaybeIncorrect,
-                    );
-                    err.emit();
-                    return Ok(true);
-                }
-                (Ok(ref a), Ok(ref b)) if a.line == b.line => {
-                    // 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.span, label_exp);
-                }
-                _ if self.prev_span == syntax_pos::DUMMY_SP => {
-                    // Account for macro context where the previous span might not be
-                    // available to avoid incorrect output (#54841).
-                    err.span_label(self.span, "unexpected token");
-                }
-                _ => {
-                    err.span_label(sp, label_exp);
-                    err.span_label(self.span, "unexpected token");
-                }
-            }
-            Err(err)
-        }
-    }
-
-    /// 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 expected_ident_found(&self) -> DiagnosticBuilder<'a> {
-        let mut err = self.struct_span_err(self.span,
-                                           &format!("expected identifier, found {}",
-                                                    self.this_token_descr()));
-        if let token::Ident(ident, false) = &self.token {
-            if ident.is_raw_guess() {
-                err.span_suggestion(
-                    self.span,
-                    "you can escape reserved keywords to use them as identifiers",
-                    format!("r#{}", ident),
-                    Applicability::MaybeIncorrect,
-                );
-            }
+            self.expected_one_of_not_found(edible, inedible)
         }
-        if let Some(token_descr) = self.token_descr() {
-            err.span_label(self.span, format!("expected identifier, found {}", token_descr));
-        } else {
-            err.span_label(self.span, "expected identifier");
-            if self.token == token::Comma && self.look_ahead(1, |t| t.is_ident()) {
-                err.span_suggestion(
-                    self.span,
-                    "remove this comma",
-                    String::new(),
-                    Applicability::MachineApplicable,
-                );
-            }
-        }
-        err
     }
 
     pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
@@ -872,8 +469,8 @@ impl<'a> Parser<'a> {
     }
 
     fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, ast::Ident> {
-        match self.token {
-            token::Ident(ident, _) => {
+        match self.token.kind {
+            token::Ident(name, _) => {
                 if self.token.is_reserved_ident() {
                     let mut err = self.expected_ident_found();
                     if recover {
@@ -882,16 +479,16 @@ impl<'a> Parser<'a> {
                         return Err(err);
                     }
                 }
-                let span = self.span;
+                let span = self.token.span;
                 self.bump();
-                Ok(Ident::new(ident.name, span))
+                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()
-                    })
+                    self.span_fatal_err(self.prev_span, Error::UselessDocComment)
+                } else {
+                    self.expected_ident_found()
+                })
             }
         }
     }
@@ -900,27 +497,27 @@ impl<'a> Parser<'a> {
     ///
     /// This method will automatically add `tok` to `expected_tokens` if `tok` is not
     /// encountered.
-    crate fn check(&mut self, tok: &token::Token) -> bool {
+    crate 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: &token::Token) -> bool {
+    pub fn eat(&mut self, tok: &TokenKind) -> bool {
         let is_present = self.check(tok);
         if is_present { self.bump() }
         is_present
     }
 
-    fn check_keyword(&mut self, kw: keywords::Keyword) -> bool {
+    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`.
-    pub fn eat_keyword(&mut self, kw: keywords::Keyword) -> bool {
+    pub fn eat_keyword(&mut self, kw: Symbol) -> bool {
         if self.check_keyword(kw) {
             self.bump();
             true
@@ -929,7 +526,7 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn eat_keyword_noexpect(&mut self, kw: keywords::Keyword) -> bool {
+    fn eat_keyword_noexpect(&mut self, kw: Symbol) -> bool {
         if self.token.is_keyword(kw) {
             self.bump();
             true
@@ -941,7 +538,7 @@ impl<'a> Parser<'a> {
     /// 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: keywords::Keyword) -> PResult<'a, ()> {
+    fn expect_keyword(&mut self, kw: Symbol) -> PResult<'a, ()> {
         if !self.eat_keyword(kw) {
             self.unexpected()
         } else {
@@ -949,7 +546,7 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn check_ident(&mut self) -> bool {
+    crate fn check_ident(&mut self) -> bool {
         if self.token.is_ident() {
             true
         } else {
@@ -992,13 +589,13 @@ impl<'a> Parser<'a> {
     /// 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 {
+        match self.token.kind {
             token::BinOp(token::Plus) => {
                 self.bump();
                 true
             }
             token::BinOpEq(token::Plus) => {
-                let span = self.span.with_lo(self.span.lo() + BytePos(1));
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
                 self.bump_with(token::Eq, span);
                 true
             }
@@ -1006,7 +603,6 @@ impl<'a> Parser<'a> {
         }
     }
 
-
     /// Checks to see if the next token is either `+` or `+=`.
     /// Otherwise returns `false`.
     fn check_plus(&mut self) -> bool {
@@ -1023,13 +619,13 @@ impl<'a> Parser<'a> {
     /// `&` 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 {
+        match self.token.kind {
             token::BinOp(token::And) => {
                 self.bump();
                 Ok(())
             }
             token::AndAnd => {
-                let span = self.span.with_lo(self.span.lo() + BytePos(1));
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
                 Ok(self.bump_with(token::BinOp(token::And), span))
             }
             _ => self.unexpected()
@@ -1040,13 +636,13 @@ impl<'a> Parser<'a> {
     /// `|` 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 {
+        match self.token.kind {
             token::BinOp(token::Or) => {
                 self.bump();
                 Ok(())
             }
             token::OrOr => {
-                let span = self.span.with_lo(self.span.lo() + BytePos(1));
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
                 Ok(self.bump_with(token::BinOp(token::Or), span))
             }
             _ => self.unexpected()
@@ -1054,7 +650,7 @@ impl<'a> Parser<'a> {
     }
 
     fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<ast::Name>) {
-        literal::expect_no_suffix(sp, &self.sess.span_diagnostic, kind, suffix)
+        literal::expect_no_suffix(&self.sess.span_diagnostic, sp, kind, suffix)
     }
 
     /// Attempts to consume a `<`. If `<<` is seen, replaces it with a single
@@ -1065,18 +661,18 @@ impl<'a> Parser<'a> {
     /// starting token.
     fn eat_lt(&mut self) -> bool {
         self.expected_tokens.push(TokenType::Token(token::Lt));
-        let ate = match self.token {
+        let ate = match self.token.kind {
             token::Lt => {
                 self.bump();
                 true
             }
             token::BinOp(token::Shl) => {
-                let span = self.span.with_lo(self.span.lo() + BytePos(1));
+                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.span.with_lo(self.span.lo() + BytePos(1));
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
                 self.bump_with(token::BinOp(token::Minus), span);
                 true
             }
@@ -1105,21 +701,21 @@ impl<'a> Parser<'a> {
     /// 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 {
+        let ate = match self.token.kind {
             token::Gt => {
                 self.bump();
                 Some(())
             }
             token::BinOp(token::Shr) => {
-                let span = self.span.with_lo(self.span.lo() + BytePos(1));
+                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.span.with_lo(self.span.lo() + BytePos(1));
+                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.span.with_lo(self.span.lo() + BytePos(1));
+                let span = self.token.span.with_lo(self.token.span.lo() + BytePos(1));
                 Some(self.bump_with(token::Eq, span))
             }
             _ => None,
@@ -1139,30 +735,16 @@ impl<'a> Parser<'a> {
         }
     }
 
-    /// Eats and discards tokens until one of `kets` is encountered. Respects token trees,
-    /// passes through any errors encountered. Used for error recovery.
-    fn eat_to_tokens(&mut self, kets: &[&token::Token]) {
-        let handler = self.diagnostic();
-
-        if let Err(ref mut err) = self.parse_seq_to_before_tokens(kets,
-                                                                  SeqSep::none(),
-                                                                  TokenExpectType::Expect,
-                                                                  |p| Ok(p.parse_token_tree())) {
-            handler.cancel(err);
-        }
-    }
-
     /// Parses a sequence, including the closing delimiter. The function
     /// `f` must consume tokens until reaching the next separator or
     /// closing bracket.
-    pub fn parse_seq_to_end<T, F>(&mut self,
-                                  ket: &token::Token,
-                                  sep: SeqSep,
-                                  f: F)
-                                  -> PResult<'a, Vec<T>> where
-        F: FnMut(&mut Parser<'a>) -> PResult<'a,  T>,
-    {
-        let (val, recovered) = self.parse_seq_to_before_end(ket, sep, f)?;
+    pub 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();
         }
@@ -1172,39 +754,39 @@ impl<'a> Parser<'a> {
     /// Parses a sequence, not including the closing delimiter. The function
     /// `f` must consume tokens until reaching the next separator or
     /// closing bracket.
-    pub fn parse_seq_to_before_end<T, F>(
+    pub fn parse_seq_to_before_end<T>(
         &mut self,
-        ket: &token::Token,
+        ket: &TokenKind,
         sep: SeqSep,
-        f: F,
-    ) -> PResult<'a, (Vec<T>, bool)>
-        where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
-    {
+        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 parse_seq_to_before_tokens<T, 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,
+            }
+        })
+    }
+
+    crate fn parse_seq_to_before_tokens<T>(
         &mut self,
-        kets: &[&token::Token],
+        kets: &[&TokenKind],
         sep: SeqSep,
         expect: TokenExpectType,
-        mut f: F,
-    ) -> PResult<'a, (Vec<T>, bool /* recovered */)>
-        where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
-    {
+        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 !kets.iter().any(|k| {
-                match expect {
-                    TokenExpectType::Expect => self.check(k),
-                    TokenExpectType::NoExpect => self.token == **k,
-                }
-            }) {
-            match self.token {
-                token::CloseDelim(..) | token::Eof => break,
-                _ => {}
-            };
+        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;
@@ -1218,7 +800,7 @@ impl<'a> Parser<'a> {
                         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) {
+                                if tokens.contains(&self.token.kind) {
                                     self.bump();
                                 }
                             }
@@ -1238,12 +820,8 @@ impl<'a> Parser<'a> {
                     }
                 }
             }
-            if sep.trailing_sep_allowed && kets.iter().any(|k| {
-                match expect {
-                    TokenExpectType::Expect => self.check(k),
-                    TokenExpectType::NoExpect => self.token == **k,
-                }
-            }) {
+            if sep.trailing_sep_allowed && self.expect_any_with_type(kets, expect) {
+                trailing = true;
                 break;
             }
 
@@ -1251,27 +829,45 @@ impl<'a> Parser<'a> {
             v.push(t);
         }
 
-        Ok((v, recovered))
+        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, F>(
+    fn parse_unspanned_seq<T>(
         &mut self,
-        bra: &token::Token,
-        ket: &token::Token,
+        bra: &TokenKind,
+        ket: &TokenKind,
         sep: SeqSep,
-        f: F,
-    ) -> PResult<'a, Vec<T>> where
-        F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
-    {
+        f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
+    ) -> PResult<'a, (Vec<T>, bool)> {
         self.expect(bra)?;
-        let (result, recovered) = self.parse_seq_to_before_end(ket, sep, f)?;
+        let (result, trailing, recovered) = self.parse_seq_to_before_end(ket, sep, f)?;
         if !recovered {
             self.eat(ket);
         }
-        Ok(result)
+        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
@@ -1281,10 +877,10 @@ impl<'a> Parser<'a> {
             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.span);
+        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 {
+        self.prev_token_kind = match self.token.kind {
             token::DocComment(..) => PrevTokenKind::DocComment,
             token::Comma => PrevTokenKind::Comma,
             token::BinOp(token::Plus) => PrevTokenKind::Plus,
@@ -1295,9 +891,7 @@ impl<'a> Parser<'a> {
             _ => PrevTokenKind::Other,
         };
 
-        let next = self.next_tok();
-        self.span = next.sp;
-        self.token = next.tok;
+        self.token = self.next_tok();
         self.expected_tokens.clear();
         // check after each token
         self.process_potential_macro_variable();
@@ -1305,125 +899,45 @@ impl<'a> Parser<'a> {
 
     /// Advance 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: token::Token, span: Span) {
-        self.prev_span = self.span.with_hi(span.lo());
+    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.span = span;
-        self.token = next;
+        self.token = Token::new(next, span);
         self.expected_tokens.clear();
     }
 
     pub fn look_ahead<R, F>(&self, dist: usize, f: F) -> R where
-        F: FnOnce(&token::Token) -> R,
+        F: FnOnce(&Token) -> R,
     {
         if dist == 0 {
-            return f(&self.token)
+            return f(&self.token);
         }
 
-        f(&match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
+        let frame = &self.token_cursor.frame;
+        f(&match frame.tree_cursor.look_ahead(dist - 1) {
             Some(tree) => match tree {
-                TokenTree::Token(_, tok) => tok,
-                TokenTree::Delimited(_, delim, _) => token::OpenDelim(delim),
-            },
-            None => token::CloseDelim(self.token_cursor.frame.delim),
+                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)
         })
     }
 
-    crate fn look_ahead_span(&self, dist: usize) -> Span {
-        if dist == 0 {
-            return self.span
-        }
-
-        match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
-            Some(TokenTree::Token(span, _)) => span,
-            Some(TokenTree::Delimited(span, ..)) => span.entire(),
-            None => self.look_ahead_span(dist - 1),
-        }
-    }
-    pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> {
-        self.sess.span_diagnostic.struct_span_fatal(self.span, m)
-    }
-    pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
-        self.sess.span_diagnostic.struct_span_fatal(sp, m)
-    }
-    fn span_fatal_err<S: Into<MultiSpan>>(&self, sp: S, err: Error) -> DiagnosticBuilder<'a> {
-        err.span_err(sp, self.diagnostic())
-    }
-    fn bug(&self, m: &str) -> ! {
-        self.sess.span_diagnostic.span_bug(self.span, m)
-    }
-    fn span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) {
-        self.sess.span_diagnostic.span_err(sp, m)
-    }
-    crate fn struct_span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
-        self.sess.span_diagnostic.struct_span_err(sp, m)
-    }
-    crate fn span_bug<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> ! {
-        self.sess.span_diagnostic.span_bug(sp, m)
-    }
-
-    fn cancel(&self, err: &mut DiagnosticBuilder<'_>) {
-        self.sess.span_diagnostic.cancel(err)
-    }
-
-    crate fn diagnostic(&self) -> &'a errors::Handler {
-        &self.sess.span_diagnostic
-    }
-
-    /// 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(keywords::Fn) ||
-            self.check_keyword(keywords::Unsafe) ||
-            self.check_keyword(keywords::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 = if self.eat_keyword(keywords::Extern) {
-            self.parse_opt_abi()?.unwrap_or(Abi::C)
-        } else {
-            Abi::Rust
-        };
-
-        self.expect_keyword(keywords::Fn)?;
-        let (inputs, c_variadic) = self.parse_fn_args(false, true)?;
-        let ret_ty = self.parse_ret_ty(false)?;
-        let decl = P(FnDecl {
-            inputs,
-            output: ret_ty,
-            c_variadic,
-        });
-        Ok(TyKind::BareFn(P(BareFnTy {
-            abi,
-            unsafety,
-            generic_params,
-            decl,
-        })))
+    /// 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(keywords::Async) {
+        if self.eat_keyword(kw::Async) {
             IsAsync::Async {
                 closure_id: ast::DUMMY_NODE_ID,
                 return_impl_trait_id: ast::DUMMY_NODE_ID,
-                arguments: Vec::new(),
             }
         } else {
             IsAsync::NotAsync
@@ -1432,365 +946,21 @@ impl<'a> Parser<'a> {
 
     /// Parses unsafety: `unsafe` or nothing.
     fn parse_unsafety(&mut self) -> Unsafety {
-        if self.eat_keyword(keywords::Unsafe) {
+        if self.eat_keyword(kw::Unsafe) {
             Unsafety::Unsafe
         } else {
             Unsafety::Normal
         }
     }
 
-    /// 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.span;
-        self.eat_bad_pub();
-        let (name, node, generics) = if self.eat_keyword(keywords::Type) {
-            self.parse_trait_item_assoc_ty()?
-        } else if self.is_const_item() {
-            self.expect_keyword(keywords::Const)?;
-            let ident = self.parse_ident()?;
-            self.expect(&token::Colon)?;
-            let ty = self.parse_ty()?;
-            let default = if self.eat(&token::Eq) {
-                let expr = self.parse_expr()?;
-                self.expect(&token::Semi)?;
-                Some(expr)
-            } else {
-                self.expect(&token::Semi)?;
-                None
-            };
-            (ident, TraitItemKind::Const(ty, default), ast::Generics::default())
-        } else if let Some(mac) = self.parse_assoc_macro_invoc("trait", None, &mut false)? {
-            // trait item macro.
-            (keywords::Invalid.ident(), ast::TraitItemKind::Macro(mac), ast::Generics::default())
-        } else {
-            let (constness, unsafety, mut asyncness, abi) = self.parse_fn_front_matter()?;
-
-            let ident = self.parse_ident()?;
-            let mut generics = self.parse_generics()?;
-
-            let mut decl = self.parse_fn_decl_with_self(|p: &mut Parser<'a>| {
-                // 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.
-                p.parse_arg_general(p.span.rust_2018(), true, false)
-            })?;
-            generics.where_clause = self.parse_where_clause()?;
-            self.construct_async_arguments(&mut asyncness, &mut decl);
-
-            let sig = ast::MethodSig {
-                header: FnHeader {
-                    unsafety,
-                    constness,
-                    abi,
-                    asyncness,
-                },
-                decl,
-            };
-
-            let body = match self.token {
-                token::Semi => {
-                    self.bump();
-                    *at_end = true;
-                    debug!("parse_trait_methods(): parsing required method");
-                    None
-                }
-                token::OpenDelim(token::Brace) => {
-                    debug!("parse_trait_methods(): 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)
-                        }
-                        _ => {
-                            let token_str = self.this_token_descr();
-                            let mut err = self.fatal(&format!("expected `;` or `{{`, found {}",
-                                                              token_str));
-                            err.span_label(self.span, "expected `;` or `{`");
-                            return Err(err);
-                        }
-                    }
-                }
-                _ => {
-                    let token_str = self.this_token_descr();
-                    let mut err = self.fatal(&format!("expected `;` or `{{`, found {}",
-                                                      token_str));
-                    err.span_label(self.span, "expected `;` or `{`");
-                    return Err(err);
-                }
-            };
-            (ident, ast::TraitItemKind::Method(sig, body), generics)
-        };
-
-        Ok(TraitItem {
-            id: ast::DUMMY_NODE_ID,
-            ident: name,
-            attrs,
-            generics,
-            node,
-            span: lo.to(self.prev_span),
-            tokens: None,
-        })
-    }
-
-    /// Parses an optional return type `[ -> TY ]` in a function declaration.
-    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.span.shrink_to_lo()))
-        }
-    }
-
-    /// 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.
-    fn parse_ty_no_plus(&mut self) -> PResult<'a, P<Ty>> {
-        self.parse_ty_common(false, true, false)
-    }
-
-    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.span;
-        let mut impl_dyn_multi = false;
-        let node = 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.node {
-                    // `(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(keywords::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(keywords::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(keywords::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.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(keywords::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(keywords::Dyn) &&
-                  (self.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 node = Mac_ { path, tts, delim };
-                TyKind::Mac(respan(lo.to(self.prev_span), node))
-            } 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(self.fatal(
-                    "only foreign functions are allowed to be C-variadic"
-                ));
-            }
-        } else {
-            let msg = format!("expected type, found {}", self.this_token_descr());
-            return Err(self.fatal(&msg));
-        };
-
-        let span = lo.to(self.prev_span);
-        let ty = P(Ty { node, span, id: ast::DUMMY_NODE_ID });
-
-        // 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_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: ty, mutbl: mutbl }));
-    }
-
-    fn parse_ptr(&mut self) -> PResult<'a, MutTy> {
-        let mutbl = if self.eat_keyword(keywords::Mut) {
-            Mutability::Mutable
-        } else if self.eat_keyword(keywords::Const) {
-            Mutability::Immutable
-        } 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: mutbl })
-    }
-
     fn is_named_argument(&self) -> bool {
-        let offset = match self.token {
+        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(keywords::Mut) => 1,
+            _ if self.token.is_keyword(kw::Mut) => 1,
             _ => 0,
         };
 
@@ -1800,88 +970,48 @@ impl<'a> Parser<'a> {
 
     /// Skips unexpected attributes and doc comments in this position and emits an appropriate
     /// error.
-    fn eat_incorrect_doc_comment(&mut self, applied_to: &str) {
-        if let token::DocComment(_) = self.token {
-            let mut err = self.diagnostic().struct_span_err(
-                self.span,
-                &format!("documentation comments cannot be applied to {}", applied_to),
-            );
-            err.span_label(self.span, "doc comments are not allowed here");
-            err.emit();
-            self.bump();
-        } else if self.token == token::Pound && self.look_ahead(1, |t| {
-            *t == token::OpenDelim(token::Bracket)
-        }) {
-            let lo = self.span;
-            // Skip every token until next possible arg.
-            while self.token != token::CloseDelim(token::Bracket) {
-                self.bump();
-            }
-            let sp = lo.to(self.span);
-            self.bump();
-            let mut err = self.diagnostic().struct_span_err(
-                sp,
-                &format!("attributes cannot be applied to {}", applied_to),
-            );
-            err.span_label(sp, "attributes are not allowed here");
-            err.emit();
-        }
-    }
-
     /// This version of parse arg doesn't necessarily require identifier names.
-    fn parse_arg_general(&mut self, require_name: bool, is_trait_item: bool,
-                         allow_c_variadic: bool) -> PResult<'a, Arg> {
-        if let Ok(Some(_)) = self.parse_self_arg() {
-            let mut err = self.struct_span_err(self.prev_span,
-                "unexpected `self` argument in function");
-            err.span_label(self.prev_span,
-                "`self` is only valid as the first argument of an associated function");
-            return Err(err);
+    fn parse_arg_general<F>(
+        &mut self,
+        is_trait_item: bool,
+        allow_c_variadic: bool,
+        is_name_required: F,
+    ) -> PResult<'a, Arg>
+    where
+        F: Fn(&token::Token) -> bool
+    {
+        let lo = self.token.span;
+        let attrs = self.parse_arg_attributes()?;
+        if let Some(mut arg) = self.parse_self_arg()? {
+            arg.attrs = attrs.into();
+            return self.recover_bad_self_arg(arg, is_trait_item);
         }
 
-        let (pat, ty) = if require_name || self.is_named_argument() {
-            debug!("parse_arg_general parse_pat (require_name:{})",
-                   require_name);
-            self.eat_incorrect_doc_comment("method arguments");
-            let pat = self.parse_pat(Some("argument name"))?;
+        let is_name_required = is_name_required(&self.token);
+        let (pat, ty) = if is_name_required || self.is_named_argument() {
+            debug!("parse_arg_general parse_pat (is_name_required:{})", is_name_required);
 
+            let pat = self.parse_pat(Some("argument name"))?;
             if let Err(mut err) = self.expect(&token::Colon) {
-                // 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)
-                }) {
-                    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,
-                    );
-                } else if require_name && is_trait_item {
-                    if let PatKind::Ident(_, ident, _) = pat.node {
-                        err.span_suggestion(
-                            pat.span,
-                            "explicitly ignore parameter",
-                            format!("_: {}", ident),
-                            Applicability::MachineApplicable,
-                        );
-                    }
-
-                    err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)");
+                if let Some(ident) = self.argument_without_type(
+                    &mut err,
+                    pat,
+                    is_name_required,
+                    is_trait_item,
+                ) {
+                    err.emit();
+                    return Ok(dummy_arg(ident));
+                } else {
+                    return Err(err);
                 }
-
-                return Err(err);
             }
 
-            self.eat_incorrect_doc_comment("a method argument's type");
+            self.eat_incorrect_doc_comment_for_arg_type();
             (pat, self.parse_ty_common(true, true, allow_c_variadic)?)
         } else {
             debug!("parse_arg_general ident_to_pat");
             let parser_snapshot_before_ty = self.clone();
-            self.eat_incorrect_doc_comment("a method argument's type");
+            self.eat_incorrect_doc_comment_for_arg_type();
             let mut ty = self.parse_ty_common(true, true, allow_c_variadic);
             if ty.is_ok() && self.token != token::Comma &&
                self.token != token::CloseDelim(token::Paren) {
@@ -1891,13 +1021,9 @@ impl<'a> Parser<'a> {
             }
             match ty {
                 Ok(ty) => {
-                    let ident = Ident::new(keywords::Invalid.name(), self.prev_span);
-                    let pat = P(Pat {
-                        id: ast::DUMMY_NODE_ID,
-                        node: PatKind::Ident(
-                            BindingMode::ByValue(Mutability::Immutable), ident, None),
-                        span: ty.span,
-                    });
+                    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)
                 }
                 Err(mut err) => {
@@ -1909,331 +1035,19 @@ impl<'a> Parser<'a> {
                     // Recover from attempting to parse the argument as a type without pattern.
                     err.cancel();
                     mem::replace(self, parser_snapshot_before_ty);
-                    let pat = self.parse_pat(Some("argument name"))?;
-                    self.expect(&token::Colon)?;
-                    let ty = self.parse_ty()?;
-
-                    let mut err = self.diagnostic().struct_span_err_with_code(
-                        pat.span,
-                        "patterns aren't allowed in methods without bodies",
-                        DiagnosticId::Error("E0642".into()),
-                    );
-                    err.span_suggestion_short(
-                        pat.span,
-                        "give this argument a name or use an underscore to ignore it",
-                        "_".to_owned(),
-                        Applicability::MachineApplicable,
-                    );
-                    err.emit();
-
-                    // Pretend the pattern is `_`, to avoid duplicate errors from AST validation.
-                    let pat = P(Pat {
-                        node: PatKind::Wild,
-                        span: pat.span,
-                        id: ast::DUMMY_NODE_ID
-                    });
-                    (pat, ty)
+                    self.recover_arg_parse()?
                 }
             }
         };
 
-        Ok(Arg { ty, pat, id: ast::DUMMY_NODE_ID, source: ast::ArgSource::Normal })
-    }
-
-    /// Parses a single function argument.
-    crate fn parse_arg(&mut self) -> PResult<'a, Arg> {
-        self.parse_arg_general(true, false, false)
-    }
+        let span = lo.to(self.token.span);
 
-    /// Parses an argument in a lambda header (e.g., `|arg, arg|`).
-    fn parse_fn_block_arg(&mut self) -> PResult<'a, Arg> {
-        let pat = self.parse_pat(Some("argument name"))?;
-        let t = if self.eat(&token::Colon) {
-            self.parse_ty()?
-        } else {
-            P(Ty {
-                id: ast::DUMMY_NODE_ID,
-                node: TyKind::Infer,
-                span: self.prev_span,
-            })
-        };
-        Ok(Arg {
-            ty: t,
-            pat,
-            id: ast::DUMMY_NODE_ID,
-            source: ast::ArgSource::Normal,
-        })
-    }
-
-    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)
-        }
-    }
-
-    /// Matches `'-' lit | lit` (cf. `ast_validation::AstValidator::check_expr_within_pat`).
-    crate fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
-        maybe_whole_expr!(self);
-
-        let minus_lo = self.span;
-        let minus_present = self.eat(&token::BinOp(token::Minus));
-        let lo = self.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)
-        }
-    }
-
-    fn parse_path_segment_ident(&mut self) -> PResult<'a, ast::Ident> {
-        match self.token {
-            token::Ident(ident, _) if self.token.is_path_segment_keyword() => {
-                let span = self.span;
-                self.bump();
-                Ok(Ident::new(ident.name, span))
-            }
-            _ => self.parse_ident(),
-        }
-    }
-
-    fn parse_ident_or_underscore(&mut self) -> PResult<'a, ast::Ident> {
-        match self.token {
-            token::Ident(ident, false) if ident.name == keywords::Underscore.name() => {
-                let span = self.span;
-                self.bump();
-                Ok(Ident::new(ident.name, span))
-            }
-            _ => self.parse_ident(),
-        }
-    }
-
-    /// 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)
-    fn parse_qpath(&mut self, style: PathStyle) -> PResult<'a, (QSelf, ast::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(keywords::As) {
-            let path_lo = self.span;
-            path = self.parse_path(PathStyle::Type)?;
-            path_span = path_lo.to(self.prev_span);
-        } else {
-            path = ast::Path { segments: Vec::new(), span: syntax_pos::DUMMY_SP };
-            path_span = self.span.to(self.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, ast::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, ast::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.span);
-        let mut segments = Vec::new();
-        let mod_sep_ctxt = self.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(ast::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.
-    pub fn parse_path_allowing_meta(&mut self, style: PathStyle) -> PResult<'a, ast::Path> {
-        let meta_ident = match self.token {
-            token::Interpolated(ref nt) => match **nt {
-                token::NtMeta(ref meta) => match meta.node {
-                    ast::MetaItemKind::Word => Some(meta.path.clone()),
-                    _ => None,
-                },
-                _ => None,
-            },
-            _ => None,
-        };
-        if let Some(path) = meta_ident {
-            self.bump();
-            return Ok(path);
-        }
-        self.parse_path(style)
-    }
-
-    crate 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(());
-            }
-        }
-    }
-
-    fn parse_path_segment(&mut self, style: PathStyle) -> PResult<'a, PathSegment> {
-        let ident = self.parse_path_segment_ident()?;
-
-        let is_args_start = |token: &token::Token| match *token {
-            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.span;
-            let args = if self.eat_lt() {
-                // `<'a, T, A = U>`
-                let (args, bindings) =
-                    self.parse_generic_args_with_leaning_angle_bracket_recovery(style, lo)?;
-                self.expect_gt()?;
-                let span = lo.to(self.prev_span);
-                AngleBracketedArgs { args, bindings, span }.into()
-            } else {
-                // `(T, U) -> R`
-                self.bump(); // `(`
-                let (inputs, recovered) = self.parse_seq_to_before_tokens(
-                    &[&token::CloseDelim(token::Paren)],
-                    SeqSep::trailing_allowed(token::Comma),
-                    TokenExpectType::Expect,
-                    |p| p.parse_ty())?;
-                if !recovered {
-                    self.bump(); // `)`
-                }
-                let span = lo.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)
-        })
-    }
-
-    crate fn check_lifetime(&mut self) -> bool {
-        self.expected_tokens.push(TokenType::Lifetime);
-        self.token.is_lifetime()
-    }
-
-    /// Parses a single lifetime `'a` or panics.
-    crate fn expect_lifetime(&mut self) -> Lifetime {
-        if let Some(ident) = self.token.lifetime() {
-            let span = self.span;
-            self.bump();
-            Lifetime { ident: Ident::new(ident.name, span), id: ast::DUMMY_NODE_ID }
-        } else {
-            self.span_bug(self.span, "not a lifetime")
-        }
-    }
-
-    fn eat_label(&mut self) -> Option<Label> {
-        if let Some(ident) = self.token.lifetime() {
-            let span = self.span;
-            self.bump();
-            Some(Label { ident: Ident::new(ident.name, span) })
-        } else {
-            None
-        }
+        Ok(Arg { attrs: attrs.into(), id: ast::DUMMY_NODE_ID, pat, span, ty })
     }
 
     /// Parses mutability (`mut` or nothing).
     fn parse_mutability(&mut self) -> Mutability {
-        if self.eat_keyword(keywords::Mut) {
+        if self.eat_keyword(kw::Mut) {
             Mutability::Mutable
         } else {
             Mutability::Immutable
@@ -2241,102 +1055,23 @@ impl<'a> Parser<'a> {
     }
 
     fn parse_field_name(&mut self) -> PResult<'a, Ident> {
-        if let token::Literal(token::Integer(name), suffix) = self.token {
-            self.expect_no_suffix(self.span, "a tuple index", suffix);
+        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(name, self.prev_span))
+            Ok(Ident::new(symbol, self.prev_span))
         } else {
             self.parse_ident_common(false)
         }
     }
 
-    /// Parse ident (COLON expr)?
-    fn parse_field(&mut self) -> PResult<'a, Field> {
-        let attrs = self.parse_outer_attributes()?;
-        let lo = self.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.span, "expected `:`, found `=`")
-                    .span_suggestion(
-                        fieldname.span.shrink_to_hi().to(self.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(),
-        })
-    }
-
-    crate fn mk_expr(&self, span: Span, node: ExprKind, attrs: ThinVec<Attribute>) -> P<Expr> {
-        P(Expr { node, span, attrs, id: ast::DUMMY_NODE_ID })
-    }
-
-    fn mk_unary(&self, unop: ast::UnOp, expr: P<Expr>) -> ast::ExprKind {
-        ExprKind::Unary(unop, expr)
-    }
-
-    fn mk_binary(&self, binop: ast::BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
-        ExprKind::Binary(binop, lhs, rhs)
-    }
-
-    fn mk_call(&self, f: P<Expr>, args: Vec<P<Expr>>) -> ast::ExprKind {
-        ExprKind::Call(f, args)
-    }
-
-    fn mk_index(&self, expr: P<Expr>, idx: P<Expr>) -> ast::ExprKind {
-        ExprKind::Index(expr, idx)
-    }
-
-    fn mk_range(&self,
-                    start: Option<P<Expr>>,
-                    end: Option<P<Expr>>,
-                    limits: RangeLimits)
-                    -> PResult<'a, ast::ExprKind> {
-        if end.is_none() && limits == RangeLimits::Closed {
-            Err(self.span_fatal_err(self.span, Error::InclusiveRangeWithNoEnd))
-        } else {
-            Ok(ExprKind::Range(start, end, limits))
-        }
-    }
-
-    fn mk_assign_op(&self, binop: ast::BinOp,
-                        lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
-        ExprKind::AssignOp(binop, lhs, rhs)
-    }
-
     fn expect_delimited_token_tree(&mut self) -> PResult<'a, (MacDelimiter, TokenStream)> {
-        let delim = match self.token {
+        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.span, msg);
+                err.span_label(self.token.span, msg);
                 return Err(err)
             }
         };
@@ -2353,461 +1088,6 @@ impl<'a> Parser<'a> {
         Ok((delim, tts.into()))
     }
 
-    /// 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.span;
-        let mut hi = self.span;
-
-        let ex: ExprKind;
-
-        // Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr().
-        match self.token {
-            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(err) => {
-                            // recover from parse error in tuple list
-                            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_lambda_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 {
-                    // Nonempty vector.
-                    let first_expr = self.parse_expr()?;
-                    if self.eat(&token::Semi) {
-                        // Repeating array syntax: [ 0; 512 ]
-                        let count = AnonConst {
-                            id: ast::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.span.rust_2018() && self.check_keyword(keywords::Async) {
-                    return if self.is_async_block() { // check for `async {` and `async move {`
-                        self.parse_async_block(attrs)
-                    } else {
-                        self.parse_lambda_expr(attrs)
-                    };
-                }
-                if self.check_keyword(keywords::Move) || self.check_keyword(keywords::Static) {
-                    return self.parse_lambda_expr(attrs);
-                }
-                if self.eat_keyword(keywords::If) {
-                    return self.parse_if_expr(attrs);
-                }
-                if self.eat_keyword(keywords::For) {
-                    let lo = self.prev_span;
-                    return self.parse_for_expr(None, lo, attrs);
-                }
-                if self.eat_keyword(keywords::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(keywords::While) {
-                        return self.parse_while_expr(Some(label), lo, attrs)
-                    }
-                    if self.eat_keyword(keywords::For) {
-                        return self.parse_for_expr(Some(label), lo, attrs)
-                    }
-                    if self.eat_keyword(keywords::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.span, msg);
-                    return Err(err);
-                }
-                if self.eat_keyword(keywords::Loop) {
-                    let lo = self.prev_span;
-                    return self.parse_loop_expr(None, lo, attrs);
-                }
-                if self.eat_keyword(keywords::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(keywords::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(keywords::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.span;
-                    assert!(self.eat_keyword(keywords::Try));
-                    return self.parse_try_block(lo, attrs);
-                }
-                if self.eat_keyword(keywords::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(keywords::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(keywords::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);
-                    }
-                } else if self.token.is_keyword(keywords::Let) {
-                    // Catch this syntax error here, instead of in `parse_ident`, so
-                    // that we can explicitly mention that let is not to be used as an expression
-                    let mut db = self.fatal("expected expression, found statement (`let`)");
-                    db.span_label(self.span, "expected expression");
-                    db.note("variable declaration using `let` is a statement");
-                    return Err(db);
-                } else if self.span.rust_2018() && self.eat_keyword(keywords::Await) {
-                    let (await_hi, e_kind) = self.parse_await_macro_or_alt(lo, self.prev_span)?;
-                    hi = await_hi;
-                    ex = e_kind;
-                } else 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(respan(lo.to(hi), Mac_ { path, tts, delim }));
-                    } 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);
-                    }
-                } 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.span, ExprKind::Err, ThinVec::new()));
-                    }
-                    match self.parse_literal_maybe_minus() {
-                        Ok(expr) => {
-                            hi = expr.span;
-                            ex = expr.node.clone();
-                        }
-                        Err(mut err) => {
-                            self.cancel(&mut err);
-                            let msg = format!("expected expression, found {}",
-                                              self.this_token_descr());
-                            let mut err = self.fatal(&msg);
-                            let sp = self.sess.source_map().start_point(self.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(self.span, "expected expression");
-                            return Err(err);
-                        }
-                    }
-                }
-            }
-        }
-
-        let expr = self.mk_expr(lo.to(hi), ex, attrs);
-        self.maybe_recover_from_bad_qpath(expr, true)
-    }
-
-    /// Parse `await!(<expr>)` calls, or alternatively recover from incorrect but reasonable
-    /// alternative syntaxes `await <expr>`, `await? <expr>`, `await(<expr>)` and
-    /// `await { <expr> }`.
-    fn parse_await_macro_or_alt(
-        &mut self,
-        lo: Span,
-        await_sp: Span,
-    ) -> PResult<'a, (Span, ExprKind)> {
-        if self.token == token::Not {
-            // Handle correct `await!(<expr>)`.
-            // FIXME: make this an error when `await!` is no longer supported
-            // https://github.com/rust-lang/rust/issues/60610
-            self.expect(&token::Not)?;
-            self.expect(&token::OpenDelim(token::Paren))?;
-            let expr = self.parse_expr().map_err(|mut err| {
-                err.span_label(await_sp, "while parsing this await macro call");
-                err
-            })?;
-            self.expect(&token::CloseDelim(token::Paren))?;
-            Ok((self.prev_span, ExprKind::Await(ast::AwaitOrigin::MacroLike, expr)))
-        } else { // Handle `await <expr>`.
-            self.parse_incorrect_await_syntax(lo, await_sp)
-        }
-    }
-
-    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) {
-                let mut err = self.diagnostic().struct_span_err(
-                    expr.span,
-                    "struct literals are not allowed here",
-                );
-                err.multipart_suggestion(
-                    "surround the struct literal with parentheses",
-                    vec![
-                        (lo.shrink_to_lo(), "(".to_string()),
-                        (expr.span.shrink_to_hi(), ")".to_string()),
-                    ],
-                    Applicability::MachineApplicable,
-                );
-                err.emit();
-            }
-            return Some(expr);
-        }
-        None
-    }
-
-    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 {
-                    let mut err = self.sess.span_diagnostic.mut_span_err(
-                        exp_span.to(self.prev_span),
-                        "cannot use a comma after the base struct",
-                    );
-                    err.span_suggestion_short(
-                        self.span,
-                        "remove this comma",
-                        String::new(),
-                        Applicability::MachineApplicable
-                    );
-                    err.note("the base struct must always be the last field");
-                    err.emit();
-                    self.recover_stmt();
-                }
-                break;
-            }
-
-            let mut recovery_field = None;
-            if let token::Ident(ident, _) = self.token {
-                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 }`
-                    let mut ident = ident.clone();
-                    ident.span = self.span;
-                    recovery_field = Some(ast::Field {
-                        ident,
-                        span: self.span,
-                        expr: self.mk_expr(self.span, ExprKind::Err, ThinVec::new()),
-                        is_shorthand: false,
-                        attrs: ThinVec::new(),
-                    });
-                }
-            }
-            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.span);
-        self.expect(&token::CloseDelim(token::Brace))?;
-        return Ok(self.mk_expr(span, ExprKind::Struct(pth, fields, base), attrs));
-    }
-
     fn parse_or_use_outer_attributes(&mut self,
                                      already_parsed_attrs: Option<ThinVec<Attribute>>)
                                      -> PResult<'a, ThinVec<Attribute>> {
@@ -2818,351 +1098,46 @@ impl<'a> Parser<'a> {
         }
     }
 
-    /// Parses a block or unsafe block.
-    crate fn parse_block_expr(
-        &mut self,
-        opt_label: Option<Label>,
-        lo: Span,
-        blk_mode: BlockCheckMode,
-        outer_attrs: ThinVec<Attribute>,
-    ) -> PResult<'a, P<Expr>> {
-        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)?;
-        return Ok(self.mk_expr(blk.span, ExprKind::Block(blk, opt_label), attrs));
-    }
-
-    /// 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)
-    }
-
-    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.node {
-                    ExprKind::If(..) | ExprKind::IfLet(..) => {
-                        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
-            })
-        )
-    }
-
-    // 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.span.rust_2018() && self.eat_keyword(keywords::Await) {
-            let span = lo.to(self.prev_span);
-            let await_expr = self.mk_expr(
-                span,
-                ExprKind::Await(ast::AwaitOrigin::FieldLike, self_arg),
-                ThinVec::new(),
-            );
-            self.recover_from_await_method_call();
-            return Ok(await_expr);
-        }
-        let segment = self.parse_path_segment(PathStyle::Expr)?;
-        self.check_trailing_angle_brackets(&segment, token::OpenDelim(token::Paren));
-
-        Ok(match self.token {
-            token::OpenDelim(token::Paren) => {
-                // Method call `expr.f()`
-                let mut args = self.parse_unspanned_seq(
-                    &token::OpenDelim(token::Paren),
-                    &token::CloseDelim(token::Paren),
-                    SeqSep::trailing_allowed(token::Comma),
-                    |p| Ok(p.parse_expr()?)
-                )?;
-                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())
-            }
-        })
-    }
-
-    /// 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
-    /// ```
-    fn check_trailing_angle_brackets(&mut self, segment: &PathSegment, end: token::Token) {
-        // 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.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.span);
-
-            let plural = number_of_gt > 1 || number_of_shr >= 1;
-            self.diagnostic()
-                .struct_span_err(
-                    span,
-                    &format!("unmatched angle bracket{}", if plural { "s" } else { "" }),
-                )
-                .span_suggestion(
-                    span,
-                    &format!("remove extra angle bracket{}", if plural { "s" } else { "" }),
-                    String::new(),
-                    Applicability::MachineApplicable,
-                )
-                .emit();
-        }
-    }
-
-    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 {
-                    token::Ident(..) => {
-                        e = self.parse_dot_suffix(e, lo)?;
-                    }
-                    token::Literal(token::Integer(name), suffix) => {
-                        let span = self.span;
-                        self.bump();
-                        let field = ExprKind::Field(e, Ident::new(name, span));
-                        e = self.mk_expr(lo.to(span), field, ThinVec::new());
-
-                        self.expect_no_suffix(span, "a tuple index", suffix);
-                    }
-                    token::Literal(token::Float(n), _suf) => {
-                      self.bump();
-                      let fstr = n.as_str();
-                      let mut err = self.diagnostic()
-                          .struct_span_err(self.prev_span, &format!("unexpected token: `{}`", n));
-                      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| {
-                              use crate::print::pprust::PrintState;
-                              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.span, &format!("unexpected token: `{}`", actual));
-                    }
-                }
-                continue;
-            }
-            if self.expr_is_complete(&e) { break; }
-            match self.token {
-                // expr(...)
-                token::OpenDelim(token::Paren) => {
-                    let seq = self.parse_unspanned_seq(
-                        &token::OpenDelim(token::Paren),
-                        &token::CloseDelim(token::Paren),
-                        SeqSep::trailing_allowed(token::Comma),
-                        |p| Ok(p.parse_expr()?)
-                    ).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.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);
-    }
-
     crate fn process_potential_macro_variable(&mut self) {
-        let (token, span) = match self.token {
-            token::Dollar if self.span.ctxt() != syntax_pos::hygiene::SyntaxContext::empty() &&
+        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 {
-                    token::Ident(ident, _) => ident,
+                let name = match self.token.kind {
+                    token::Ident(name, _) => name,
                     _ => unreachable!()
                 };
-                let mut err = self.fatal(&format!("unknown macro variable `{}`", name));
-                err.span_label(self.span, "unknown macro variable");
-                err.emit();
+                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.span);
+                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::Ident(ident, is_raw), ident.span),
-                    token::NtLifetime(ident) => (token::Lifetime(ident), ident.span),
+                    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,
         };
-        self.token = token;
-        self.span = span;
     }
 
     /// Parses a single token tree from the input.
     crate fn parse_token_tree(&mut self) -> TokenTree {
-        match self.token {
+        match self.token.kind {
             token::OpenDelim(..) => {
                 let frame = mem::replace(&mut self.token_cursor.frame,
                                          self.token_cursor.stack.pop().unwrap());
-                self.span = frame.span.entire();
+                self.token.span = frame.span.entire();
                 self.bump();
                 TokenTree::Delimited(
                     frame.span,
@@ -3172,15 +1147,14 @@ impl<'a> Parser<'a> {
             },
             token::CloseDelim(_) | token::Eof => unreachable!(),
             _ => {
-                let (token, span) = (mem::replace(&mut self.token, token::Whitespace), self.span);
+                let token = self.token.take();
                 self.bump();
-                TokenTree::Token(span, token)
+                TokenTree::Token(token)
             }
         }
     }
 
-    // parse a stream of tokens into a list of TokenTree's,
-    // up to EOF.
+    /// 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 {
@@ -3192,7 +1166,7 @@ impl<'a> Parser<'a> {
     pub fn parse_tokens(&mut self) -> TokenStream {
         let mut result = Vec::new();
         loop {
-            match self.token {
+            match self.token.kind {
                 token::Eof | token::CloseDelim(..) => break,
                 _ => result.push(self.parse_token_tree().into()),
             }
@@ -3200,823 +1174,6 @@ impl<'a> Parser<'a> {
         TokenStream::new(result)
     }
 
-    /// Parse 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.span;
-        // Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr()
-        let (hi, ex) = match self.token {
-            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;
-                let mut err = self.diagnostic()
-                    .struct_span_err(span_of_tilde, "`~` cannot be used as a unary operator");
-                err.span_suggestion_short(
-                    span_of_tilde,
-                    "use `!` to perform bitwise negation",
-                    "!".to_owned(),
-                    Applicability::MachineApplicable
-                );
-                err.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(keywords::In) => {
-                self.bump();
-                let place = self.parse_expr_res(
-                    Restrictions::NO_STRUCT_LITERAL,
-                    None,
-                )?;
-                let blk = self.parse_block()?;
-                let span = blk.span;
-                let blk_expr = self.mk_expr(span, ExprKind::Block(blk, None), ThinVec::new());
-                (lo.to(span), ExprKind::ObsoleteInPlace(place, blk_expr))
-            }
-            token::Ident(..) if self.token.is_keyword(keywords::Box) => {
-                self.bump();
-                let e = self.parse_prefix_expr(None);
-                let (span, e) = self.interpolated_or_expr_span(e)?;
-                (lo.to(span), ExprKind::Box(e))
-            }
-            token::Ident(..) if self.token.is_ident_named("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::Token| match *t {
-                    // These tokens can start an expression after `!`, but
-                    // can't continue an expression after an ident
-                    token::Ident(ident, is_raw) => token::ident_can_begin_expr(ident, is_raw),
-                    token::Literal(..) | token::Pound => true,
-                    token::Interpolated(ref nt) => match **nt {
-                        token::NtIdent(..) | token::NtExpr(..) |
-                        token::NtBlock(..) | token::NtPath(..) => true,
-                        _ => false,
-                    },
-                    _ => false
-                };
-                let cannot_continue_expr = self.look_ahead(1, token_cannot_continue_expr);
-                if cannot_continue_expr {
-                    self.bump();
-                    // Emit the error ...
-                    let mut err = self.diagnostic()
-                        .struct_span_err(self.span,
-                                         &format!("unexpected {} after identifier",
-                                                  self.this_token_descr()));
-                    // span the `not` plus trailing whitespace to avoid
-                    // trailing whitespace after the `!` in our suggestion
-                    let to_replace = self.sess.source_map()
-                        .span_until_non_whitespace(lo.to(self.span));
-                    err.span_suggestion_short(
-                        to_replace,
-                        "use `!` to perform logical negation",
-                        "!".to_owned(),
-                        Applicability::MachineApplicable
-                    );
-                    err.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));
-    }
-
-    /// 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.
-    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) {
-                return self.parse_prefix_range_expr(attrs);
-            } else {
-                self.parse_prefix_expr(attrs)?
-            }
-        };
-
-        match (self.expr_is_complete(&lhs), AssocOp::from_token(&self.token)) {
-            (true, 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::Add)) => { // `{ 42 } + 42
-                // These cases are ambiguous and can't be identified in the parser alone
-                let sp = self.sess.source_map().start_point(self.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() => {
-                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.sess.span_diagnostic.struct_span_err(self.span, &format!(
-                    "expected expression, found `{}`",
-                    pprust::token_to_string(&self.token),
-                ));
-                err.span_label(self.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.node) {
-                (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.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.span);
-            }
-
-            self.bump();
-            if op.is_comparison() {
-                self.check_no_chained_comparison(&lhs, &op);
-            }
-            // 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.node);
-                let next_sp = self.span;
-
-                lhs = match self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Type) {
-                    Ok(lhs) => lhs,
-                    Err(mut err) => {
-                        self.bad_type_ascription(
-                            &mut err,
-                            lhs_span,
-                            cur_op_span,
-                            next_sp,
-                            maybe_path,
-                        );
-                        return Err(err);
-                    }
-                };
-                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::ObsoleteInPlace =>
-                    self.mk_expr(span, ExprKind::ObsoleteInPlace(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 }
-        }
-        Ok(lhs)
-    }
-
-    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 {
-                            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 {}", path, op_noun);
-                        let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &msg);
-                        err.span_label(self.look_ahead_span(1).to(parser_snapshot_after_type.span),
-                                       "interpreted as generic arguments");
-                        err.span_label(self.span, format!("not interpreted as {}", op_noun));
-
-                        let expr = mk_expr(self, P(Ty {
-                            span: path.span,
-                            node: TyKind::Path(None, path),
-                            id: ast::DUMMY_NODE_ID
-                        }));
-
-                        let expr_str = self.sess.source_map().span_to_snippet(expr.span)
-                                                .unwrap_or_else(|_| pprust::expr_to_string(&expr));
-                        err.span_suggestion(
-                            expr.span,
-                            &format!("try {} the cast value", op_verb),
-                            format!("({})", expr_str),
-                            Applicability::MachineApplicable
-                        );
-                        err.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)
-                    }
-                }
-            }
-        }
-    }
-
-    /// Produce an error if comparison operators are chained (RFC #558).
-    /// We only need to check lhs, not rhs, because all comparison ops
-    /// have same precedence and are left-associative
-    fn check_no_chained_comparison(&self, lhs: &Expr, outer_op: &AssocOp) {
-        debug_assert!(outer_op.is_comparison(),
-                      "check_no_chained_comparison: {:?} is not comparison",
-                      outer_op);
-        match lhs.node {
-            ExprKind::Binary(op, _, _) if op.node.is_comparison() => {
-                // respan to include both operators
-                let op_span = op.span.to(self.span);
-                let mut err = self.diagnostic().struct_span_err(op_span,
-                    "chained comparison operators require parentheses");
-                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, ()>>>
-                    err.help(
-                        "use `::<...>` instead of `<...>` if you meant to specify type arguments");
-                    err.help("or use `(...)` if you meant to specify fn arguments");
-                }
-                err.emit();
-            }
-            _ => {}
-        }
-    }
-
-    /// Parse 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.span);
-        }
-
-        debug_assert!([token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token),
-                      "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.span;
-        let mut hi = self.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))
-    }
-
-    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 an `if` or `if let` expression (`if` token already eaten).
-    fn parse_if_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
-        if self.check_keyword(keywords::Let) {
-            return self.parse_if_let_expr(attrs);
-        }
-        let lo = self.prev_span;
-        let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
-
-        // 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(keywords::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` statemement");
-            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(keywords::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 an `if let` expression (`if` token already eaten).
-    fn parse_if_let_expr(&mut self, attrs: ThinVec<Attribute>)
-                             -> PResult<'a, P<Expr>> {
-        let lo = self.prev_span;
-        self.expect_keyword(keywords::Let)?;
-        let pats = self.parse_pats()?;
-        self.expect(&token::Eq)?;
-        let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
-        let thn = self.parse_block()?;
-        let (hi, els) = if self.eat_keyword(keywords::Else) {
-            let expr = self.parse_else_expr()?;
-            (expr.span, Some(expr))
-        } else {
-            (thn.span, None)
-        };
-        Ok(self.mk_expr(lo.to(hi), ExprKind::IfLet(pats, expr, thn, els), attrs))
-    }
-
-    /// Parses `move |args| expr`.
-    fn parse_lambda_expr(&mut self,
-                             attrs: ThinVec<Attribute>)
-                             -> PResult<'a, P<Expr>>
-    {
-        let lo = self.span;
-        let movability = if self.eat_keyword(keywords::Static) {
-            Movability::Static
-        } else {
-            Movability::Movable
-        };
-        let asyncness = if self.span.rust_2018() {
-            self.parse_asyncness()
-        } else {
-            IsAsync::NotAsync
-        };
-        let capture_clause = if self.eat_keyword(keywords::Move) {
-            CaptureBy::Value
-        } else {
-            CaptureBy::Ref
-        };
-        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.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))
-    }
-
-    // `else` token already eaten
-    fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
-        if self.eat_keyword(keywords::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()));
-        }
-    }
-
-    /// Parse 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>`
-
-        let pat = self.parse_top_level_pat()?;
-        if !self.eat_keyword(keywords::In) {
-            let in_span = self.prev_span.between(self.span);
-            let mut err = self.sess.span_diagnostic
-                .struct_span_err(in_span, "missing `in` in `for` loop");
-            err.span_suggestion_short(
-                in_span, "try adding `in` here", " in ".into(),
-                // has been misleading, at least in the past (closed Issue #48492)
-                Applicability::MaybeIncorrect
-            );
-            err.emit();
-        }
-        let in_span = self.prev_span;
-        if self.eat_keyword(keywords::In) {
-            // a common typo: `for _ in in bar {}`
-            let mut err = self.sess.span_diagnostic.struct_span_err(
-                self.prev_span,
-                "expected iterable, found keyword `in`",
-            );
-            err.span_suggestion_short(
-                in_span.until(self.prev_span),
-                "remove the duplicated `in`",
-                String::new(),
-                Applicability::MachineApplicable,
-            );
-            err.note("if you meant to use emplacement syntax, it is obsolete (for now, anyway)");
-            err.note("for more information on the status of emplacement syntax, see <\
-                      https://github.com/rust-lang/rust/issues/27779#issuecomment-378416911>");
-            err.emit();
-        }
-        let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
-        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>> {
-        if self.token.is_keyword(keywords::Let) {
-            return self.parse_while_let_expr(opt_label, span_lo, attrs);
-        }
-        let cond = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
-        let (iattrs, body) = self.parse_inner_attrs_and_block()?;
-        attrs.extend(iattrs);
-        let span = span_lo.to(body.span);
-        return Ok(self.mk_expr(span, ExprKind::While(cond, body, opt_label), attrs));
-    }
-
-    /// Parses a `while let` expression (`while` token already eaten).
-    fn parse_while_let_expr(&mut self, opt_label: Option<Label>,
-                                span_lo: Span,
-                                mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
-        self.expect_keyword(keywords::Let)?;
-        let pats = self.parse_pats()?;
-        self.expect(&token::Eq)?;
-        let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
-        let (iattrs, body) = self.parse_inner_attrs_and_block()?;
-        attrs.extend(iattrs);
-        let span = span_lo.to(body.span);
-        return Ok(self.mk_expr(span, ExprKind::WhileLet(pats, expr, body, opt_label), attrs));
-    }
-
-    // parse `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))
-    }
-
-    /// Parses an `async move {...}` expression.
-    pub fn parse_async_block(&mut self, mut attrs: ThinVec<Attribute>)
-        -> PResult<'a, P<Expr>>
-    {
-        let span_lo = self.span;
-        self.expect_keyword(keywords::Async)?;
-        let capture_clause = if self.eat_keyword(keywords::Move) {
-            CaptureBy::Value
-        } else {
-            CaptureBy::Ref
-        };
-        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, ast::DUMMY_NODE_ID, body), attrs))
-    }
-
-    /// 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(keywords::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 {
-            Ok(self.mk_expr(span_lo.to(body.span), ExprKind::TryBlock(body), attrs))
-        }
-    }
-
-    // `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::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.span);
-                    if self.token == token::CloseDelim(token::Brace) {
-                        self.bump();
-                    }
-                    return Ok(self.mk_expr(span, ExprKind::Match(discriminant, arms), attrs));
-                }
-            }
-        }
-        let hi = self.span;
-        self.bump();
-        return Ok(self.mk_expr(lo.to(hi), ExprKind::Match(discriminant, arms), attrs));
-    }
-
-    crate fn parse_arm(&mut self) -> PResult<'a, Arm> {
-        let attrs = self.parse_outer_attributes()?;
-        let pats = self.parse_pats()?;
-        let guard = if self.eat_keyword(keywords::If) {
-            Some(Guard::If(self.parse_expr()?))
-        } else {
-            None
-        };
-        let arrow_span = self.span;
-        self.expect(&token::FatArrow)?;
-        let arm_start_span = self.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);
-
-        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.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,
-            pats,
-            guard,
-            body: expr,
-        })
-    }
-
-    /// Parses an expression.
-    #[inline]
-    pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
-        self.parse_expr_res(Restrictions::empty(), None)
-    }
-
     /// Evaluates the closure with restrictions in place.
     ///
     /// Afters the closure is evaluated, restrictions are reset.
@@ -4031,1963 +1188,54 @@ impl<'a> Parser<'a> {
 
     }
 
-    /// Parses an expression, subject to the given restrictions.
-    #[inline]
-    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 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)
-        }
-    }
-
-    /// Parses patterns, separated by '|' s.
-    fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
-        // Allow a '|' before the pats (RFC 1925 + RFC 2530)
-        self.eat(&token::BinOp(token::Or));
-
-        let mut pats = Vec::new();
-        loop {
-            pats.push(self.parse_top_level_pat()?);
-
-            if self.token == token::OrOr {
-                let mut err = self.struct_span_err(self.span,
-                                                   "unexpected token `||` after pattern");
-                err.span_suggestion(
-                    self.span,
-                    "use a single `|` to specify multiple patterns",
-                    "|".to_owned(),
-                    Applicability::MachineApplicable
-                );
-                err.emit();
-                self.bump();
-            } else if self.eat(&token::BinOp(token::Or)) {
-                // This is a No-op. Continue the loop to parse the next
-                // pattern.
-            } else {
-                return Ok(pats);
-            }
-        };
-    }
-
-    // Parses a parenthesized list of patterns like
-    // `()`, `(p)`, `(p,)`, `(p, q)`, or `(p, .., q)`. Returns:
-    // - a vector of the patterns that were parsed
-    // - an option indicating the index of the `..` element
-    // - a boolean indicating whether a trailing comma was present.
-    // Trailing commas are significant because (p) and (p,) are different patterns.
-    fn parse_parenthesized_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
-        self.expect(&token::OpenDelim(token::Paren))?;
-        let result = match self.parse_pat_list() {
-            Ok(result) => result,
-            Err(mut err) => { // recover from parse error in tuple pattern list
-                err.emit();
-                self.consume_block(token::Paren);
-                return Ok((vec![], Some(0), false));
-            }
-        };
-        self.expect(&token::CloseDelim(token::Paren))?;
-        Ok(result)
-    }
-
-    fn parse_pat_list(&mut self) -> PResult<'a, (Vec<P<Pat>>, Option<usize>, bool)> {
-        let mut fields = Vec::new();
-        let mut ddpos = None;
-        let mut prev_dd_sp = None;
-        let mut trailing_comma = false;
-        loop {
-            if self.eat(&token::DotDot) {
-                if ddpos.is_none() {
-                    ddpos = Some(fields.len());
-                    prev_dd_sp = Some(self.prev_span);
-                } else {
-                    // Emit a friendly error, ignore `..` and continue parsing
-                    let mut err = self.struct_span_err(
-                        self.prev_span,
-                        "`..` can only be used once per tuple or tuple struct pattern",
-                    );
-                    err.span_label(self.prev_span, "can only be used once per pattern");
-                    if let Some(sp) = prev_dd_sp {
-                        err.span_label(sp, "previously present here");
-                    }
-                    err.emit();
-                }
-            } else if !self.check(&token::CloseDelim(token::Paren)) {
-                fields.push(self.parse_pat(None)?);
-            } else {
-                break
-            }
-
-            trailing_comma = self.eat(&token::Comma);
-            if !trailing_comma {
-                break
-            }
-        }
-
-        if ddpos == Some(fields.len()) && trailing_comma {
-            // `..` needs to be followed by `)` or `, pat`, `..,)` is disallowed.
-            let msg = "trailing comma is not permitted after `..`";
-            self.struct_span_err(self.prev_span, msg)
-                .span_label(self.prev_span, msg)
-                .emit();
-        }
-
-        Ok((fields, ddpos, trailing_comma))
-    }
-
-    fn parse_pat_vec_elements(
-        &mut self,
-    ) -> PResult<'a, (Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>)> {
-        let mut before = Vec::new();
-        let mut slice = None;
-        let mut after = Vec::new();
-        let mut first = true;
-        let mut before_slice = true;
-
-        while self.token != token::CloseDelim(token::Bracket) {
-            if first {
-                first = false;
-            } else {
-                self.expect(&token::Comma)?;
-
-                if self.token == token::CloseDelim(token::Bracket)
-                        && (before_slice || !after.is_empty()) {
-                    break
-                }
-            }
-
-            if before_slice {
-                if self.eat(&token::DotDot) {
-
-                    if self.check(&token::Comma) ||
-                            self.check(&token::CloseDelim(token::Bracket)) {
-                        slice = Some(P(Pat {
-                            id: ast::DUMMY_NODE_ID,
-                            node: PatKind::Wild,
-                            span: self.prev_span,
-                        }));
-                        before_slice = false;
-                    }
-                    continue
-                }
-            }
-
-            let subpat = self.parse_pat(None)?;
-            if before_slice && self.eat(&token::DotDot) {
-                slice = Some(subpat);
-                before_slice = false;
-            } else if before_slice {
-                before.push(subpat);
-            } else {
-                after.push(subpat);
-            }
-        }
-
-        Ok((before, slice, after))
-    }
-
-    fn parse_pat_field(
-        &mut self,
-        lo: Span,
-        attrs: Vec<Attribute>
-    ) -> PResult<'a, source_map::Spanned<ast::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(None)?;
-            hi = pat.span;
-            (pat, fieldname, false)
-        } else {
-            // Parsing a pattern of the form "(box) (ref) (mut) fieldname"
-            let is_box = self.eat_keyword(keywords::Box);
-            let boxed_span = self.span;
-            let is_ref = self.eat_keyword(keywords::Ref);
-            let is_mut = self.eat_keyword(keywords::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 = P(Pat {
-                id: ast::DUMMY_NODE_ID,
-                node: PatKind::Ident(bind_type, fieldname, None),
-                span: boxed_span.to(hi),
-            });
-
-            let subpat = if is_box {
-                P(Pat {
-                    id: ast::DUMMY_NODE_ID,
-                    node: PatKind::Box(fieldpat),
-                    span: lo.to(hi),
-                })
-            } else {
-                fieldpat
-            };
-            (subpat, fieldname, true)
-        };
-
-        Ok(source_map::Spanned {
-            span: lo.to(hi),
-            node: ast::FieldPat {
-                ident: fieldname,
-                pat: subpat,
-                is_shorthand,
-                attrs: attrs.into(),
-           }
-        })
-    }
-
-    /// Parses the fields of a struct-like pattern.
-    fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<source_map::Spanned<ast::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 = self.parse_outer_attributes()?;
-            let lo = self.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.span;
-
-                if self.token == token::DotDotDot { // Issue #46718
-                    // Accept `...` as if it were `..` to avoid further errors
-                    let mut err = self.struct_span_err(self.span,
-                                                       "expected field pattern, found `...`");
-                    err.span_suggestion(
-                        self.span,
-                        "to omit remaining fields, use one fewer `.`",
-                        "..".to_owned(),
-                        Applicability::MachineApplicable
-                    );
-                    err.emit();
-                }
-                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.span, "expected `}`");
-                let mut comma_sp = None;
-                if self.token == token::Comma { // Issue #49257
-                    etc_sp = etc_sp.to(self.sess.source_map().span_until_non_whitespace(self.span));
-                    err.span_label(etc_sp,
-                                   "`..` must be at the end and cannot have a trailing comma");
-                    comma_sp = Some(self.span);
-                    self.bump();
-                    ate_comma = true;
-                }
-
-                etc_span = Some(etc_sp.until(self.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);
+    fn parse_fn_args(&mut self, named_args: bool, allow_c_variadic: bool)
+                     -> PResult<'a, (Vec<Arg> , bool)> {
+        let sp = self.token.span;
+        let mut c_variadic = false;
+        let (args, _): (Vec<Option<Arg>>, _) = self.parse_paren_comma_seq(|p| {
+            let do_not_enforce_named_arguments_for_c_variadic =
+                |token: &token::Token| -> bool {
+                    if token == &token::DotDotDot {
+                        false
                     } 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();
+                        named_args
                     }
-                    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.span, format!("{}.. }}", if ate_comma { "" } else { ", " })),
-                    ],
-                    Applicability::MachineApplicable,
-                );
-            }
-            err.emit();
-        }
-        return Ok((fields, etc));
-    }
-
-    fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
-        if self.token.is_path_start() {
-            let lo = self.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()
-        }
-    }
-
-    // helper function to decide whether to parse as ident binding or to try to do
-    // something more complex like range patterns
-    fn parse_as_ident(&mut self) -> bool {
-        self.look_ahead(1, |t| match *t {
-            token::OpenDelim(token::Paren) | token::OpenDelim(token::Brace) |
-            token::DotDotDot | token::DotDotEq | token::ModSep | token::Not => Some(false),
-            // ensure slice patterns [a, b.., c] and [a, b, c..] don't go into the
-            // range pattern branch
-            token::DotDot => None,
-            _ => Some(true),
-        }).unwrap_or_else(|| self.look_ahead(2, |t| match *t {
-            token::Comma | token::CloseDelim(token::Bracket) => true,
-            _ => false,
-        }))
-    }
-
-    /// A wrapper around `parse_pat` with some special error handling for the
-    /// "top-level" patterns in a match arm, `for` loop, `let`, &c. (in contrast
-    /// to subpatterns within such).
-    fn parse_top_level_pat(&mut self) -> PResult<'a, P<Pat>> {
-        let pat = self.parse_pat(None)?;
-        if self.token == token::Comma {
-            // 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.span;
-            self.bump();
-            if let Err(mut err) = self.parse_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 = pat.span.to(self.prev_span);
-            let mut err = self.struct_span_err(comma_span,
-                                               "unexpected `,` in pattern");
-            if let Ok(seq_snippet) = self.sess.source_map().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
-                );
-            }
-            return Err(err);
-        }
-        Ok(pat)
-    }
-
-    /// Parses a pattern.
-    pub fn parse_pat(&mut self, expected: Option<&'static str>) -> PResult<'a, P<Pat>> {
-        self.parse_pat_with_range_pat(true, expected)
-    }
-
-    /// 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: Option<&'static str>,
-    ) -> PResult<'a, P<Pat>> {
-        maybe_recover_from_interpolated_ty_qpath!(self, true);
-        maybe_whole!(self, NtPat, |x| x);
-
-        let lo = self.span;
-        let pat;
-        match self.token {
-            token::BinOp(token::And) | token::AndAnd => {
-                // Parse &pat / &mut pat
-                self.expect_and()?;
-                let mutbl = self.parse_mutability();
-                if let token::Lifetime(ident) = self.token {
-                    let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern",
-                                                      ident));
-                    err.span_label(self.span, "unexpected lifetime");
-                    return Err(err);
-                }
-                let subpat = self.parse_pat_with_range_pat(false, expected)?;
-                pat = PatKind::Ref(subpat, mutbl);
-            }
-            token::OpenDelim(token::Paren) => {
-                // Parse (pat,pat,pat,...) as tuple pattern
-                let (fields, ddpos, trailing_comma) = self.parse_parenthesized_pat_list()?;
-                pat = if fields.len() == 1 && ddpos.is_none() && !trailing_comma {
-                    PatKind::Paren(fields.into_iter().nth(0).unwrap())
-                } else {
-                    PatKind::Tuple(fields, ddpos)
-                };
-            }
-            token::OpenDelim(token::Bracket) => {
-                // Parse [pat,pat,...] as slice pattern
-                self.bump();
-                let (before, slice, after) = self.parse_pat_vec_elements()?;
-                self.expect(&token::CloseDelim(token::Bracket))?;
-                pat = PatKind::Slice(before, slice, after);
-            }
-            // At this point, token != &, &&, (, [
-            _ => if self.eat_keyword(keywords::Underscore) {
-                // Parse _
-                pat = PatKind::Wild;
-            } else if self.eat_keyword(keywords::Mut) {
-                // Parse mut ident @ pat / mut ref ident @ pat
-                let mutref_span = self.prev_span.to(self.span);
-                let binding_mode = if self.eat_keyword(keywords::Ref) {
-                    self.diagnostic()
-                        .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();
-                    BindingMode::ByRef(Mutability::Mutable)
-                } else {
-                    BindingMode::ByValue(Mutability::Mutable)
-                };
-                pat = self.parse_pat_ident(binding_mode)?;
-            } else if self.eat_keyword(keywords::Ref) {
-                // Parse ref ident @ pat / ref mut ident @ pat
-                let mutbl = self.parse_mutability();
-                pat = self.parse_pat_ident(BindingMode::ByRef(mutbl))?;
-            } else if self.eat_keyword(keywords::Box) {
-                // Parse box pat
-                let subpat = self.parse_pat_with_range_pat(false, None)?;
-                pat = PatKind::Box(subpat);
-            } else if self.token.is_ident() && !self.token.is_reserved_ident() &&
-                      self.parse_as_ident() {
-                // Parse ident @ pat
-                // This can give false positives and parse nullary enums,
-                // they are dealt with later in resolve
-                let binding_mode = BindingMode::ByValue(Mutability::Immutable);
-                pat = self.parse_pat_ident(binding_mode)?;
-            } else if self.token.is_path_start() {
-                // 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 {
-                    token::Not if qself.is_none() => {
-                        // Parse macro invocation
-                        self.bump();
-                        let (delim, tts) = self.expect_delimited_token_tree()?;
-                        let mac = respan(lo.to(self.prev_span), Mac_ { path, tts, delim });
-                        pat = PatKind::Mac(mac);
-                    }
-                    token::DotDotDot | token::DotDotEq | token::DotDot => {
-                        let end_kind = match self.token {
-                            token::DotDot => RangeEnd::Excluded,
-                            token::DotDotDot => RangeEnd::Included(RangeSyntax::DotDotDot),
-                            token::DotDotEq => RangeEnd::Included(RangeSyntax::DotDotEq),
-                            _ => panic!("can only parse `..`/`...`/`..=` for ranges \
-                                         (checked above)"),
-                        };
-                        let op_span = self.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()?;
-                        let op = Spanned { span: op_span, node: end_kind };
-                        pat = PatKind::Range(begin, end, op);
-                    }
-                    token::OpenDelim(token::Brace) => {
-                        if qself.is_some() {
-                            let msg = "unexpected `{` after qualified path";
-                            let mut err = self.fatal(msg);
-                            err.span_label(self.span, msg);
-                            return Err(err);
-                        }
-                        // Parse struct pattern
-                        self.bump();
-                        let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
-                            e.emit();
-                            self.recover_stmt();
-                            (vec![], true)
-                        });
-                        self.bump();
-                        pat = PatKind::Struct(path, fields, etc);
-                    }
-                    token::OpenDelim(token::Paren) => {
-                        if qself.is_some() {
-                            let msg = "unexpected `(` after qualified path";
-                            let mut err = self.fatal(msg);
-                            err.span_label(self.span, msg);
-                            return Err(err);
-                        }
-                        // Parse tuple struct or enum pattern
-                        let (fields, ddpos, _) = self.parse_parenthesized_pat_list()?;
-                        pat = PatKind::TupleStruct(path, fields, ddpos)
-                    }
-                    _ => pat = PatKind::Path(qself, path),
-                }
-            } else {
-                // Try to parse everything else as literal with optional minus
-                match self.parse_literal_maybe_minus() {
-                    Ok(begin) => {
-                        let op_span = self.span;
-                        if self.check(&token::DotDot) || self.check(&token::DotDotEq) ||
-                                self.check(&token::DotDotDot) {
-                            let end_kind = 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) {
-                                RangeEnd::Excluded
-                            } else {
-                                panic!("impossible case: we already matched \
-                                        on a range-operator token")
-                            };
-                            let end = self.parse_pat_range_end()?;
-                            let op = Spanned { span: op_span, node: end_kind };
-                            pat = PatKind::Range(begin, end, op);
+            match p.parse_arg_general(
+                false,
+                allow_c_variadic,
+                do_not_enforce_named_arguments_for_c_variadic
+            ) {
+                Ok(arg) => {
+                    if let TyKind::CVarArgs = arg.ty.node {
+                        c_variadic = true;
+                        if p.token != token::CloseDelim(token::Paren) {
+                            let span = p.token.span;
+                            p.span_err(span,
+                                "`...` must be the last argument of a C-variadic function");
+                            Ok(None)
                         } else {
-                            pat = PatKind::Lit(begin);
-                        }
-                    }
-                    Err(mut err) => {
-                        self.cancel(&mut err);
-                        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.span, format!("expected {}", expected));
-                        let sp = self.sess.source_map().start_point(self.span);
-                        if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow().get(&sp) {
-                            self.sess.expr_parentheses_needed(&mut err, *sp, None);
-                        }
-                        return Err(err);
-                    }
-                }
-            }
-        }
-
-        let pat = P(Pat { node: pat, span: lo.to(self.prev_span), id: ast::DUMMY_NODE_ID });
-        let pat = self.maybe_recover_from_bad_qpath(pat, true)?;
-
-        if !allow_range_pat {
-            match pat.node {
-                PatKind::Range(
-                    _, _, Spanned { node: RangeEnd::Included(RangeSyntax::DotDotDot), .. }
-                ) => {},
-                PatKind::Range(..) => {
-                    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
-                    );
-                    return Err(err);
-                }
-                _ => {}
-            }
-        }
-
-        Ok(pat)
-    }
-
-    /// 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: ast::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))
-    }
-
-    /// 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_level_pat()?;
-
-        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.sess.source_map().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.span
-        } else {
-            self.prev_span
-        };
-        Ok(P(ast::Local {
-            ty,
-            pat,
-            init,
-            id: ast::DUMMY_NODE_ID,
-            span: lo.to(hi),
-            attrs,
-            source: LocalSource::Normal,
-        }))
-    }
-
-    /// 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: ast::DUMMY_NODE_ID,
-            ty,
-            attrs,
-        })
-    }
-
-    /// Emits an expected-item-after-attributes error.
-    fn expected_item_err(&mut self, attrs: &[Attribute]) -> PResult<'a,  ()> {
-        let message = match attrs.last() {
-            Some(&Attribute { is_sugared_doc: true, .. }) => "expected item after doc comment",
-            _ => "expected item after attributes",
-        };
-
-        let mut err = self.diagnostic().struct_span_err(self.prev_span, message);
-        if attrs.last().unwrap().is_sugared_doc {
-            err.span_label(self.prev_span, "this doc comment doesn't document anything");
-        }
-        Err(err)
-    }
-
-    /// Parse 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 is_async_block(&self) -> bool {
-        self.token.is_keyword(keywords::Async) &&
-        (
-            ( // `async move {`
-                self.look_ahead(1, |t| t.is_keyword(keywords::Move)) &&
-                self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))
-            ) || ( // `async {`
-                self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace))
-            )
-        )
-    }
-
-    fn is_async_fn(&self) -> bool {
-        self.token.is_keyword(keywords::Async) &&
-            self.look_ahead(1, |t| t.is_keyword(keywords::Fn))
-    }
-
-    fn is_do_catch_block(&self) -> bool {
-        self.token.is_keyword(keywords::Do) &&
-        self.look_ahead(1, |t| t.is_keyword(keywords::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(keywords::Try) &&
-        self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) &&
-        self.span.rust_2018() &&
-        // prevent `while try {} {}`, `if try {} {} else {}`, etc.
-        !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
-    }
-
-    fn is_union_item(&self) -> bool {
-        self.token.is_keyword(keywords::Union) &&
-        self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
-    }
-
-    fn is_crate_vis(&self) -> bool {
-        self.token.is_keyword(keywords::Crate) && self.look_ahead(1, |t| t != &token::ModSep)
-    }
-
-    fn is_existential_type_decl(&self) -> bool {
-        self.token.is_keyword(keywords::Existential) &&
-        self.look_ahead(1, |t| t.is_keyword(keywords::Type))
-    }
-
-    fn is_auto_trait_item(&self) -> bool {
-        // auto trait
-        (self.token.is_keyword(keywords::Auto)
-            && self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
-        || // unsafe auto trait
-        (self.token.is_keyword(keywords::Unsafe) &&
-         self.look_ahead(1, |t| t.is_keyword(keywords::Auto)) &&
-         self.look_ahead(2, |t| t.is_keyword(keywords::Trait)))
-    }
-
-    fn eat_macro_def(&mut self, attrs: &[Attribute], vis: &Visibility, lo: Span)
-                     -> PResult<'a, Option<P<Item>>> {
-        let token_lo = self.span;
-        let (ident, def) = match self.token {
-            token::Ident(ident, false) if ident.name == keywords::Macro.name() => {
-                self.bump();
-                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_lo.to(self.prev_span), token::FatArrow).into(),
-                        body.into(),
-                    ])
-                } else {
-                    self.unexpected()?;
-                    unreachable!()
-                };
-
-                (ident, ast::MacroDef { tokens: tokens.into(), legacy: false })
-            }
-            token::Ident(ident, _) if ident.name == sym::macro_rules &&
-                                   self.look_ahead(1, |t| *t == token::Not) => {
-                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: tokens, legacy: true })
-            }
-            _ => return Ok(None),
-        };
-
-        let span = lo.to(self.prev_span);
-        Ok(Some(self.mk_item(span, ident, ItemKind::MacroDef(def), vis.clone(), attrs.to_vec())))
-    }
-
-    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.span;
-
-        Ok(Some(if self.eat_keyword(keywords::Let) {
-            Stmt {
-                id: ast::DUMMY_NODE_ID,
-                node: StmtKind::Local(self.parse_local(attrs.into())?),
-                span: lo.to(self.prev_span),
-            }
-        } else if let Some(macro_def) = self.eat_macro_def(
-            &attrs,
-            &source_map::respan(lo, VisibilityKind::Inherited),
-            lo,
-        )? {
-            Stmt {
-                id: ast::DUMMY_NODE_ID,
-                node: 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_existential_type_decl() &&
-                  !self.is_auto_trait_item() &&
-                  !self.is_async_fn() {
-            let pth = self.parse_path(PathStyle::Expr)?;
-
-            if !self.eat(&token::Not) {
-                let expr = if self.check(&token::OpenDelim(token::Brace)) {
-                    self.parse_struct_expr(lo, pth, ThinVec::new())?
-                } else {
-                    let hi = self.prev_span;
-                    self.mk_expr(lo.to(hi), ExprKind::Path(None, pth), 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: ast::DUMMY_NODE_ID,
-                    node: StmtKind::Expr(expr),
-                    span: lo.to(self.prev_span),
-                }));
-            }
-
-            // it's a macro invocation
-            let id = match self.token {
-                token::OpenDelim(_) => keywords::Invalid.ident(), // no special identifier
-                _ => self.parse_ident()?,
-            };
-
-            // check that we're pointing at delimiters (need to check
-            // again after the `if`, because of `parse_ident`
-            // consuming more tokens).
-            match self.token {
-                token::OpenDelim(_) => {}
-                _ => {
-                    // we only expect an ident if we didn't parse one
-                    // above.
-                    let ident_str = if id.name == keywords::Invalid.name() {
-                        "identifier, "
-                    } else {
-                        ""
-                    };
-                    let tok_str = self.this_token_descr();
-                    let mut err = self.fatal(&format!("expected {}`(` or `{{`, found {}",
-                                                      ident_str,
-                                                      tok_str));
-                    err.span_label(self.span, format!("expected {}`(` or `{{`", ident_str));
-                    return Err(err)
-                },
-            }
-
-            let (delim, tts) = self.expect_delimited_token_tree()?;
-            let hi = self.prev_span;
-
-            let style = if delim == MacDelimiter::Brace {
-                MacStmtStyle::Braces
-            } else {
-                MacStmtStyle::NoBraces
-            };
-
-            if id.name == keywords::Invalid.name() {
-                let mac = respan(lo.to(hi), Mac_ { path: pth, tts, delim });
-                let node = 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 {
-                    // 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: ast::DUMMY_NODE_ID,
-                    span: lo.to(hi),
-                    node,
-                }
-            } else {
-                // if it has a special ident, it's definitely an item
-                //
-                // Require a semicolon or braces.
-                if style != MacStmtStyle::Braces && !self.eat(&token::Semi) {
-                    self.report_invalid_macro_expansion_item();
-                }
-                let span = lo.to(hi);
-                Stmt {
-                    id: ast::DUMMY_NODE_ID,
-                    span,
-                    node: StmtKind::Item({
-                        self.mk_item(
-                            span, id /*id is good here*/,
-                            ItemKind::Mac(respan(span, Mac_ { path: pth, tts, delim })),
-                            respan(lo, VisibilityKind::Inherited),
-                            attrs)
-                    }),
-                }
-            }
-        } 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: ast::DUMMY_NODE_ID,
-                    span: lo.to(i.span),
-                    node: 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.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();
-                        return Ok(None);
-                    }
-
-                    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: ast::DUMMY_NODE_ID,
-                        span: lo.to(e.span),
-                        node: StmtKind::Expr(e),
-                    }
-                }
-            }
-        }))
-    }
-
-    /// 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)
-    }
-
-    /// 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.span;
-
-        if !self.eat(&token::OpenDelim(token::Brace)) {
-            let sp = self.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(keywords::In) || self.token == token::Colon;
-
-            if self.token.is_ident_named("and") {
-                e.span_suggestion_short(
-                    self.span,
-                    "use `&&` instead of `and` for the boolean operator",
-                    "&&".to_string(),
-                    Applicability::MaybeIncorrect,
-                );
-            }
-            if self.token.is_ident_named("or") {
-                e.span_suggestion_short(
-                    self.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());
-                    }
-                    let sugg = pprust::to_string(|s| {
-                        use crate::print::pprust::{PrintState, INDENT_UNIT};
-                        s.ibox(INDENT_UNIT)?;
-                        s.bopen()?;
-                        s.print_stmt(&stmt)?;
-                        s.bclose_maybe_open(stmt.span, INDENT_UNIT, false)
-                    });
-                    e.span_suggestion(
-                        stmt_span,
-                        "try placing this code inside a block",
-                        sugg,
-                        // speculative, has been misleading in the past (closed Issue #46836)
-                        Applicability::MaybeIncorrect
-                    );
-                }
-                Err(mut e) => {
-                    self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
-                    self.cancel(&mut e);
-                }
-                _ => ()
-            }
-            e.span_label(sp, "expected `{`");
-            return Err(e);
-        }
-
-        self.parse_block_tail(lo, BlockCheckMode::Default)
-    }
-
-    /// Parses a block. Inner attributes are allowed.
-    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.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 '{'.
-    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)) {
-            let stmt = match self.parse_full_stmt(false) {
-                Err(mut err) => {
-                    err.emit();
-                    self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore);
-                    Some(Stmt {
-                        id: ast::DUMMY_NODE_ID,
-                        node: StmtKind::Expr(DummyResult::raw_expr(self.span, true)),
-                        span: self.span,
-                    })
-                }
-                Ok(stmt) => stmt,
-            };
-            if let Some(stmt) = stmt {
-                stmts.push(stmt);
-            } else if self.token == token::Eof {
-                break;
-            } else {
-                // Found only `;` or `}`.
-                continue;
-            };
-        }
-        Ok(P(ast::Block {
-            stmts,
-            id: ast::DUMMY_NODE_ID,
-            rules: s,
-            span: lo.to(self.prev_span),
-        }))
-    }
-
-    /// Parses a statement, including the trailing semicolon.
-    crate 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),
-        };
-
-        match stmt.node {
-            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();
-                    }
-                }
-            }
-            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_one_of(&[], &[token::Semi])?;
-                }
-            }
-            _ => {}
-        }
-
-        if self.eat(&token::Semi) {
-            stmt = stmt.add_trailing_semicolon();
-        }
-
-        stmt.span = stmt.span.with_hi(self.prev_span.hi());
-        Ok(Some(stmt))
-    }
-
-    fn warn_missing_semicolon(&self) {
-        self.diagnostic().struct_span_warn(self.span, {
-            &format!("expected `;`, found {}", self.this_token_descr())
-        }).note({
-            "This was erroneously allowed and will become a hard error in a future release"
-        }).emit();
-    }
-
-    fn err_dotdotdot_syntax(&self, span: Span) {
-        self.diagnostic().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();
-    }
-
-    /// 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 `Token::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(keywords::For) ||
-                                 self.check(&token::OpenDelim(token::Paren));
-            if is_bound_start {
-                let lo = self.span;
-                let has_parens = self.eat(&token::OpenDelim(token::Paren));
-                let inner_lo = self.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.sess.source_map().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));
+                            Ok(Some(arg))
                         }
                     } 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));
+                        Ok(Some(arg))
                     }
-                }
-            } 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 plural = negative_bounds.len() > 1;
-            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.sess.source_map().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{}", if plural { "s" } else { "" }),
-                    new_bound_list,
-                    Applicability::MachineApplicable,
-                );
-            }
-            err.emit();
-        }
-
-        return Ok(bounds);
-    }
-
-    crate 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 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,
-            }
-        })
-    }
-
-    /// Parses the following grammar:
-    ///
-    ///     TraitItemAssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty]
-    fn parse_trait_item_assoc_ty(&mut self)
-        -> PResult<'a, (Ident, TraitItemKind, ast::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(&token::Semi)?;
-
-        Ok((ident, TraitItemKind::Type(bounds, default), generics))
-    }
-
-    fn parse_const_param(&mut self, preceding_attrs: Vec<Attribute>) -> PResult<'a, GenericParam> {
-        self.expect_keyword(keywords::Const)?;
-        let ident = self.parse_ident()?;
-        self.expect(&token::Colon)?;
-        let ty = self.parse_ty()?;
-
-        Ok(GenericParam {
-            ident,
-            id: ast::DUMMY_NODE_ID,
-            attrs: preceding_attrs.into(),
-            bounds: Vec::new(),
-            kind: GenericParamKind::Const {
-                ty,
-            }
-        })
-    }
-
-    /// Parses a (possibly empty) list of lifetime and type parameters, possibly including
-    /// a trailing comma and erroneous trailing attributes.
-    crate 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,
-                });
-            } else if self.check_keyword(keywords::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 {
-                // Check for trailing attributes and stop parsing.
-                if !attrs.is_empty() {
-                    if !params.is_empty() {
-                        self.struct_span_err(
-                            attrs[0].span,
-                            &format!("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 )
-    fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
-        let span_lo = self.span;
-        if self.eat_lt() {
-            let params = self.parse_generic_params()?;
-            self.expect_gt()?;
-            Ok(ast::Generics {
-                params,
-                where_clause: WhereClause {
-                    id: ast::DUMMY_NODE_ID,
-                    predicates: Vec::new(),
-                    span: syntax_pos::DUMMY_SP,
                 },
-                span: span_lo.to(self.prev_span),
-            })
-        } else {
-            Ok(ast::Generics::default())
-        }
-    }
-
-    /// 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<TypeBinding>)> {
-        // 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)
-                );
-                let plural = snapshot.unmatched_angle_bracket_count > 1;
-                self.diagnostic()
-                    .struct_span_err(
-                        span,
-                        &format!(
-                            "unmatched angle bracket{}",
-                            if plural { "s" } else { "" }
-                        ),
-                    )
-                    .span_suggestion(
-                        span,
-                        &format!(
-                            "remove extra angle bracket{}",
-                            if plural { "s" } else { "" }
-                        ),
-                        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<TypeBinding>)> {
-        let mut args = Vec::new();
-        let mut bindings = Vec::new();
-        let mut misplaced_assoc_ty_bindings: Vec<Span> = Vec::new();
-        let mut assoc_ty_bindings: Vec<Span> = Vec::new();
-
-        let args_lo = self.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_bindings.append(&mut assoc_ty_bindings);
-            } else if self.check_ident() && self.look_ahead(1, |t| t == &token::Eq) {
-                // Parse associated type binding.
-                let lo = self.span;
-                let ident = self.parse_ident()?;
-                self.bump();
-                let ty = self.parse_ty()?;
-                let span = lo.to(self.prev_span);
-                bindings.push(TypeBinding {
-                    id: ast::DUMMY_NODE_ID,
-                    ident,
-                    ty,
-                    span,
-                });
-                assoc_ty_bindings.push(span);
-            } else if self.check_const_arg() {
-                // Parse const argument.
-                let expr = if let token::OpenDelim(token::Brace) = self.token {
-                    self.parse_block_expr(None, self.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.
-                    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_bindings.append(&mut assoc_ty_bindings);
-            } else if self.check_type() {
-                // Parse type argument.
-                args.push(GenericArg::Type(self.parse_ty()?));
-                misplaced_assoc_ty_bindings.append(&mut assoc_ty_bindings);
-            } 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_bindings.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_bindings {
-                err.span_label(
-                    span,
-                    "this associated type binding should be moved after the generic parameters",
-                );
-            }
-            err.emit();
-        }
-
-        Ok((args, bindings))
-    }
-
-    /// Parses an optional where-clause and places it in `generics`.
-    ///
-    /// ```ignore (only-for-syntax-highlight)
-    /// where T : Trait<U, V> + 'b, 'a : 'b
-    /// ```
-    fn parse_where_clause(&mut self) -> PResult<'a, WhereClause> {
-        let mut where_clause = WhereClause {
-            id: ast::DUMMY_NODE_ID,
-            predicates: Vec::new(),
-            span: syntax_pos::DUMMY_SP,
-        };
-
-        if !self.eat_keyword(keywords::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.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() {
-                // 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.
-                // Example 1: for<'a> Trait1<'a>: Trait2<'a /*ok*/>
-                // Example 2: (for<'a> Trait1<'a>): Trait2<'a /*not ok*/>
-                // Example 3: 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))?;
-                    where_clause.predicates.push(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()?;
-                    where_clause.predicates.push(ast::WherePredicate::EqPredicate(
-                        ast::WhereEqPredicate {
-                            span: lo.to(self.prev_span),
-                            lhs_ty: ty,
-                            rhs_ty,
-                            id: ast::DUMMY_NODE_ID,
-                        }
-                    ));
-                } else {
-                    return self.unexpected();
+                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))))
                 }
-            } else {
-                break
             }
-
-            if !self.eat(&token::Comma) {
-                break
-            }
-        }
-
-        where_clause.span = lo.to(self.prev_span);
-        Ok(where_clause)
-    }
-
-    fn parse_fn_args(&mut self, named_args: bool, allow_c_variadic: bool)
-                     -> PResult<'a, (Vec<Arg> , bool)> {
-        self.expect(&token::OpenDelim(token::Paren))?;
-
-        let sp = self.span;
-        let mut c_variadic = false;
-        let (args, recovered): (Vec<Option<Arg>>, bool) =
-            self.parse_seq_to_before_end(
-                &token::CloseDelim(token::Paren),
-                SeqSep::trailing_allowed(token::Comma),
-                |p| {
-                    // If the argument is a C-variadic argument we should not
-                    // enforce named arguments.
-                    let enforce_named_args = if p.token == token::DotDotDot {
-                        false
-                    } else {
-                        named_args
-                    };
-                    match p.parse_arg_general(enforce_named_args, false,
-                                              allow_c_variadic) {
-                        Ok(arg) => {
-                            if let TyKind::CVarArgs = arg.ty.node {
-                                c_variadic = true;
-                                if p.token != token::CloseDelim(token::Paren) {
-                                    let span = p.span;
-                                    p.span_err(span,
-                                        "`...` must be the last argument of a C-variadic function");
-                                    Ok(None)
-                                } else {
-                                    Ok(Some(arg))
-                                }
-                            } else {
-                                Ok(Some(arg))
-                            }
-                        },
-                        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(span)))
-                        }
-                    }
-                }
-            )?;
-
-        if !recovered {
-            self.eat(&token::CloseDelim(token::Paren));
-        }
+        })?;
 
         let args: Vec<_> = args.into_iter().filter_map(|x| x).collect();
 
-        if c_variadic && args.is_empty() {
+        if c_variadic && args.len() <= 1 {
             self.span_err(sp,
                           "C-variadic function must be declared with at least one named argument");
         }
@@ -5995,47 +1243,36 @@ impl<'a> Parser<'a> {
         Ok((args, c_variadic))
     }
 
-    /// Parses the argument list and result type of a function declaration.
-    fn parse_fn_decl(&mut self, allow_c_variadic: bool) -> PResult<'a, P<FnDecl>> {
-
-        let (args, c_variadic) = self.parse_fn_args(true, allow_c_variadic)?;
-        let ret_ty = self.parse_ret_ty(true)?;
-
-        Ok(P(FnDecl {
-            inputs: args,
-            output: ret_ty,
-            c_variadic,
-        }))
-    }
-
     /// Returns the parsed optional self argument and whether a self shortcut was used.
+    ///
+    /// See `parse_self_arg_with_attrs` to collect attributes.
     fn parse_self_arg(&mut self) -> PResult<'a, Option<Arg>> {
-        let expect_ident = |this: &mut Self| match this.token {
+        let expect_ident = |this: &mut Self| match this.token.kind {
             // Preserve hygienic context.
-            token::Ident(ident, _) =>
-                { let span = this.span; this.bump(); Ident::new(ident.name, span) }
+            token::Ident(name, _) =>
+                { let span = this.token.span; this.bump(); Ident::new(name, span) }
             _ => unreachable!()
         };
         let isolated_self = |this: &mut Self, n| {
-            this.look_ahead(n, |t| t.is_keyword(keywords::SelfLower)) &&
+            this.look_ahead(n, |t| t.is_keyword(kw::SelfLower)) &&
             this.look_ahead(n + 1, |t| t != &token::ModSep)
         };
 
-        // Parse optional self parameter of a method.
-        // Only a limited set of initial token sequences is considered self parameters, anything
+        // 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.span;
-        let (eself, eself_ident, eself_hi) = match self.token {
+        let eself_lo = self.token.span;
+        let (eself, eself_ident, eself_hi) = match self.token.kind {
             token::BinOp(token::And) => {
-                // &self
-                // &mut self
-                // &'lt self
-                // &'lt mut self
-                // &not_self
+                // `&self`
+                // `&mut self`
+                // `&'lt self`
+                // `&'lt mut self`
+                // `&not_self`
                 (if isolated_self(self, 1) {
                     self.bump();
                     SelfKind::Region(None, Mutability::Immutable)
-                } else if self.look_ahead(1, |t| t.is_keyword(keywords::Mut)) &&
+                } else if self.is_keyword_ahead(1, &[kw::Mut]) &&
                           isolated_self(self, 2) {
                     self.bump();
                     self.bump();
@@ -6046,7 +1283,7 @@ impl<'a> Parser<'a> {
                     let lt = self.expect_lifetime();
                     SelfKind::Region(Some(lt), Mutability::Immutable)
                 } else if self.look_ahead(1, |t| t.is_lifetime()) &&
-                          self.look_ahead(2, |t| t.is_keyword(keywords::Mut)) &&
+                          self.is_keyword_ahead(2, &[kw::Mut]) &&
                           isolated_self(self, 3) {
                     self.bump();
                     let lt = self.expect_lifetime();
@@ -6057,24 +1294,24 @@ impl<'a> Parser<'a> {
                 }, expect_ident(self), self.prev_span)
             }
             token::BinOp(token::Star) => {
-                // *self
-                // *const self
-                // *mut self
-                // *not_self
+                // `*self`
+                // `*const self`
+                // `*mut self`
+                // `*not_self`
                 // Emit special error for `self` cases.
                 let msg = "cannot pass `self` by raw pointer";
                 (if isolated_self(self, 1) {
                     self.bump();
-                    self.struct_span_err(self.span, msg)
-                        .span_label(self.span, msg)
+                    self.struct_span_err(self.token.span, msg)
+                        .span_label(self.token.span, msg)
                         .emit();
                     SelfKind::Value(Mutability::Immutable)
                 } else if self.look_ahead(1, |t| t.is_mutability()) &&
                           isolated_self(self, 2) {
                     self.bump();
                     self.bump();
-                    self.struct_span_err(self.span, msg)
-                        .span_label(self.span, msg)
+                    self.struct_span_err(self.token.span, msg)
+                        .span_label(self.token.span, msg)
                         .emit();
                     SelfKind::Value(Mutability::Immutable)
                 } else {
@@ -6083,8 +1320,8 @@ impl<'a> Parser<'a> {
             }
             token::Ident(..) => {
                 if isolated_self(self, 0) {
-                    // self
-                    // self: TYPE
+                    // `self`
+                    // `self: TYPE`
                     let eself_ident = expect_ident(self);
                     let eself_hi = self.prev_span;
                     (if self.eat(&token::Colon) {
@@ -6093,10 +1330,10 @@ impl<'a> Parser<'a> {
                     } else {
                         SelfKind::Value(Mutability::Immutable)
                     }, eself_ident, eself_hi)
-                } else if self.token.is_keyword(keywords::Mut) &&
+                } else if self.token.is_keyword(kw::Mut) &&
                           isolated_self(self, 1) {
-                    // mut self
-                    // mut self: TYPE
+                    // `mut self`
+                    // `mut self: TYPE`
                     self.bump();
                     let eself_ident = expect_ident(self);
                     let eself_hi = self.prev_span;
@@ -6114,7 +1351,18 @@ impl<'a> Parser<'a> {
         };
 
         let eself = source_map::respan(eself_lo.to(eself_hi), eself);
-        Ok(Some(Arg::from_self(eself, eself_ident)))
+        Ok(Some(Arg::from_self(ThinVec::default(), eself, eself_ident)))
+    }
+
+    /// Returns the parsed optional self argument with attributes and whether a self
+    /// shortcut was used.
+    fn parse_self_arg_with_attrs(&mut self) -> PResult<'a, Option<Arg>> {
+        let attrs = self.parse_arg_attributes()?;
+        let arg_opt = self.parse_self_arg()?;
+        Ok(arg_opt.map(|mut arg| {
+            arg.attrs = attrs.into();
+            arg
+        }))
     }
 
     /// Parses the parameter list and result type of a function that may have a `self` parameter.
@@ -6123,17 +1371,17 @@ impl<'a> Parser<'a> {
     {
         self.expect(&token::OpenDelim(token::Paren))?;
 
-        // Parse optional self argument
-        let self_arg = self.parse_self_arg()?;
+        // Parse optional self argument.
+        let self_arg = self.parse_self_arg_with_attrs()?;
 
         // Parse the rest of the function parameter list.
         let sep = SeqSep::trailing_allowed(token::Comma);
-        let (fn_inputs, recovered) = if let Some(self_arg) = self_arg {
+        let (mut fn_inputs, recovered) = if let Some(self_arg) = self_arg {
             if self.check(&token::CloseDelim(token::Paren)) {
                 (vec![self_arg], false)
             } else if self.eat(&token::Comma) {
                 let mut fn_inputs = vec![self_arg];
-                let (mut input, recovered) = self.parse_seq_to_before_end(
+                let (mut input, _, recovered) = self.parse_seq_to_before_end(
                     &token::CloseDelim(token::Paren), sep, parse_arg_fn)?;
                 fn_inputs.append(&mut input);
                 (fn_inputs, recovered)
@@ -6144,13 +1392,18 @@ impl<'a> Parser<'a> {
                 }
             }
         } else {
-            self.parse_seq_to_before_end(&token::CloseDelim(token::Paren), sep, parse_arg_fn)?
+            let (input, _, recovered) =
+                self.parse_seq_to_before_end(&token::CloseDelim(token::Paren), sep, parse_arg_fn)?;
+            (input, recovered)
         };
 
         if !recovered {
             // Parse closing paren and return type.
             self.expect(&token::CloseDelim(token::Paren))?;
         }
+        // Replace duplicated recovered arguments with `_` pattern to avoid unecessary errors.
+        self.deduplicate_recovered_arg_names(&mut fn_inputs);
+
         Ok(P(FnDecl {
             inputs: fn_inputs,
             output: self.parse_ret_ty(true)?,
@@ -6158,682 +1411,8 @@ impl<'a> Parser<'a> {
         }))
     }
 
-    /// 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_arg()
-                )?.0;
-                self.expect_or()?;
-                args
-            }
-        };
-        let output = self.parse_ret_ty(true)?;
-
-        Ok(P(FnDecl {
-            inputs: inputs_captures,
-            output,
-            c_variadic: false
-        }))
-    }
-
-    /// Parses the name and optional generic types of a function header.
-    fn parse_fn_header(&mut self) -> PResult<'a, (Ident, ast::Generics)> {
-        let id = self.parse_ident()?;
-        let generics = self.parse_generics()?;
-        Ok((id, generics))
-    }
-
-    fn mk_item(&self, span: Span, ident: Ident, node: ItemKind, vis: Visibility,
-               attrs: Vec<Attribute>) -> P<Item> {
-        P(Item {
-            ident,
-            attrs,
-            id: ast::DUMMY_NODE_ID,
-            node,
-            vis,
-            span,
-            tokens: None,
-        })
-    }
-
-    /// Parses an item-position function declaration.
-    fn parse_item_fn(&mut self,
-                     unsafety: Unsafety,
-                     mut asyncness: Spanned<IsAsync>,
-                     constness: Spanned<Constness>,
-                     abi: Abi)
-                     -> PResult<'a, ItemInfo> {
-        let (ident, mut generics) = self.parse_fn_header()?;
-        let allow_c_variadic = abi == Abi::C && unsafety == Unsafety::Unsafe;
-        let mut decl = self.parse_fn_decl(allow_c_variadic)?;
-        generics.where_clause = self.parse_where_clause()?;
-        let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
-        self.construct_async_arguments(&mut asyncness, &mut decl);
-        let header = FnHeader { unsafety, asyncness, constness, abi };
-        Ok((ident, ItemKind::Fn(decl, header, generics, body), Some(inner_attrs)))
-    }
-
-    /// 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(keywords::Const) &&
-            !self.look_ahead(1, |t| t.is_keyword(keywords::Fn)) &&
-            !self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe))
-    }
-
-    /// 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, (
-            Spanned<Constness>,
-            Unsafety,
-            Spanned<IsAsync>,
-            Abi
-        )>
-    {
-        let is_const_fn = self.eat_keyword(keywords::Const);
-        let const_span = self.prev_span;
-        let unsafety = self.parse_unsafety();
-        let asyncness = self.parse_asyncness();
-        let asyncness = respan(self.prev_span, asyncness);
-        let (constness, unsafety, abi) = if is_const_fn {
-            (respan(const_span, Constness::Const), unsafety, Abi::Rust)
-        } else {
-            let abi = if self.eat_keyword(keywords::Extern) {
-                self.parse_opt_abi()?.unwrap_or(Abi::C)
-            } else {
-                Abi::Rust
-            };
-            (respan(self.prev_span, Constness::NotConst), unsafety, abi)
-        };
-        if !self.eat_keyword(keywords::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((constness, unsafety, asyncness, abi))
-    }
-
-    /// 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.span;
-        let vis = self.parse_visibility(false)?;
-        let defaultness = self.parse_defaultness();
-        let (name, node, generics) = if let Some(type_) = self.eat_type() {
-            let (name, alias, generics) = type_?;
-            let kind = match alias {
-                AliasKind::Weak(typ) => ast::ImplItemKind::Type(typ),
-                AliasKind::Existential(bounds) => ast::ImplItemKind::Existential(bounds),
-            };
-            (name, kind, generics)
-        } else if self.is_const_item() {
-            // This parses the grammar:
-            //     ImplItemConst = "const" Ident ":" Ty "=" Expr ";"
-            self.expect_keyword(keywords::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(&token::Semi)?;
-            (name, ast::ImplItemKind::Const(typ, expr), ast::Generics::default())
-        } else {
-            let (name, inner_attrs, generics, node) = self.parse_impl_method(&vis, at_end)?;
-            attrs.extend(inner_attrs);
-            (name, node, generics)
-        };
-
-        Ok(ImplItem {
-            id: ast::DUMMY_NODE_ID,
-            span: lo.to(self.prev_span),
-            ident: name,
-            vis,
-            defaultness,
-            attrs,
-            generics,
-            node,
-            tokens: None,
-        })
-    }
-
-    fn complain_if_pub_macro(&self, vis: &VisibilityKind, sp: Span) {
-        match *vis {
-            VisibilityKind::Inherited => {}
-            _ => {
-                let is_macro_rules: bool = match self.token {
-                    token::Ident(sid, _) => sid.name == Symbol::intern("macro_rules"),
-                    _ => false,
-                };
-                let mut err = if is_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 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
-    }
-
-    /// Parse a method or a macro invocation in a trait impl.
-    fn parse_impl_method(&mut self, vis: &Visibility, at_end: &mut bool)
-                         -> PResult<'a, (Ident, Vec<Attribute>, ast::Generics,
-                             ast::ImplItemKind)> {
-        // code copied from parse_macro_use_or_failure... abstraction!
-        if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(vis), at_end)? {
-            // method macro
-            Ok((keywords::Invalid.ident(), vec![], ast::Generics::default(),
-                ast::ImplItemKind::Macro(mac)))
-        } else {
-            let (constness, unsafety, mut asyncness, abi) = self.parse_fn_front_matter()?;
-            let ident = self.parse_ident()?;
-            let mut generics = self.parse_generics()?;
-            let mut decl = self.parse_fn_decl_with_self(|p| p.parse_arg())?;
-            generics.where_clause = self.parse_where_clause()?;
-            self.construct_async_arguments(&mut asyncness, &mut decl);
-            *at_end = true;
-            let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
-            let header = ast::FnHeader { abi, unsafety, constness, asyncness };
-            Ok((ident, inner_attrs, generics, ast::ImplItemKind::Method(
-                ast::MethodSig { header, decl },
-                body
-            )))
-        }
-    }
-
-    /// Parses `trait Foo { ... }` or `trait Foo = Bar;`.
-    fn parse_item_trait(&mut self, is_auto: IsAuto, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
-        let ident = self.parse_ident()?;
-        let mut tps = self.parse_generics()?;
-
-        // Parse optional colon and supertrait bounds.
-        let bounds = if self.eat(&token::Colon) {
-            self.parse_generic_bounds(Some(self.prev_span))?
-        } else {
-            Vec::new()
-        };
-
-        if self.eat(&token::Eq) {
-            // it's a trait alias
-            let bounds = self.parse_generic_bounds(None)?;
-            tps.where_clause = self.parse_where_clause()?;
-            self.expect(&token::Semi)?;
-            if is_auto == IsAuto::Yes {
-                let msg = "trait aliases cannot be `auto`";
-                self.struct_span_err(self.prev_span, msg)
-                    .span_label(self.prev_span, msg)
-                    .emit();
-            }
-            if unsafety != Unsafety::Normal {
-                let msg = "trait aliases cannot be `unsafe`";
-                self.struct_span_err(self.prev_span, msg)
-                    .span_label(self.prev_span, msg)
-                    .emit();
-            }
-            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 {
-                    if self.look_ahead(1,
-                    |tok| tok == &token::Token::CloseDelim(token::Brace)) {
-                        let mut err = self.diagnostic().struct_span_err_with_code(
-                            self.span,
-                            "found a documentation comment that doesn't document anything",
-                            DiagnosticId::Error("E0584".into()),
-                        );
-                        err.help("doc comments must come before what they document, maybe a \
-                            comment was intended with `//`?",
-                        );
-                        err.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.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
-                        }
-                    }
-                }
-            }
-            Ok((ident, ItemKind::Trait(is_auto, unsafety, tps, bounds, trait_items), None))
-        }
-    }
-
-    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.look_ahead(1, |t| t.is_keyword(keywords::Const)))
-    }
-
-    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.recover_stmt_(SemiColonMode::Break, BlockMode::Break);
-                    }
-                }
-            }
-        }
-        Ok((impl_items, attrs))
-    }
-
-    /// 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 {
-            ast::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(keywords::Invalid.name(), span));
-        let ty_first = if self.token.is_keyword(keywords::For) &&
-                          self.look_ahead(1, |t| t != &token::Lt) {
-            let span = self.prev_span.between(self.span);
-            self.struct_span_err(span, "missing trait in a trait impl").emit();
-            P(Ty { node: TyKind::Path(None, err_path(span)), span, id: ast::DUMMY_NODE_ID })
-        } else {
-            self.parse_ty()?
-        };
-
-        // If `for` is missing we try to recover.
-        let has_for = self.eat_keyword(keywords::For);
-        let missing_for_span = self.prev_span.between(self.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(DummyResult::raw_ty(self.prev_span, true))
-        } 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.node {
-                    // 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((keywords::Invalid.ident(), item_kind, Some(attrs)))
-    }
-
-    fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> {
-        if self.eat_keyword(keywords::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())
-        }
-    }
-
-    /// 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(keywords::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(ast::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(ast::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()?, ast::DUMMY_NODE_ID);
-            generics.where_clause = self.parse_where_clause()?;
-            self.expect(&token::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.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(keywords::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.span, "expected `where` or `{` after union name");
-            return Err(err);
-        };
-
-        Ok((class_name, ItemKind::Union(vdata, generics), None))
-    }
-
-    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.recover_stmt();
-                    recovered = true;
-                    e
-                });
-                match field {
-                    Ok(field) => fields.push(field),
-                    Err(mut err) => {
-                        err.emit();
-                    }
-                }
-            }
-            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.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
-        let fields = self.parse_unspanned_seq(
-            &token::OpenDelim(token::Paren),
-            &token::CloseDelim(token::Paren),
-            SeqSep::trailing_allowed(token::Comma),
-            |p| {
-                let attrs = p.parse_outer_attributes()?;
-                let lo = p.span;
-                let vis = p.parse_visibility(true)?;
-                let ty = p.parse_ty()?;
-                Ok(StructField {
-                    span: lo.to(ty.span),
-                    vis,
-                    ident: None,
-                    id: ast::DUMMY_NODE_ID,
-                    ty,
-                    attrs,
-                })
-            })?;
-
-        Ok(fields)
-    }
-
-    /// 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 {
-            token::Comma => {
-                self.bump();
-            }
-            token::CloseDelim(token::Brace) => {}
-            token::DocComment(_) => {
-                let previous_span = self.prev_span;
-                let mut err = self.span_fatal_err(self.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 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.span;
-        let vis = self.parse_visibility(false)?;
-        self.parse_single_struct_field(lo, vis, attrs)
+    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)`,
@@ -6844,17 +1423,17 @@ impl<'a> Parser<'a> {
     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(keywords::Crate));
+        self.expected_tokens.push(TokenType::Keyword(kw::Crate));
         if self.is_crate_vis() {
             self.bump(); // `crate`
             return Ok(respan(self.prev_span, VisibilityKind::Crate(CrateSugar::JustCrate)));
         }
 
-        if !self.eat_keyword(keywords::Pub) {
+        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.span.shrink_to_lo(), VisibilityKind::Inherited))
+            return Ok(respan(self.token.span.shrink_to_lo(), VisibilityKind::Inherited))
         }
         let lo = self.prev_span;
 
@@ -6863,7 +1442,7 @@ impl<'a> Parser<'a> {
             // `()` 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.look_ahead(1, |t| t.is_keyword(keywords::Crate)) &&
+            if self.is_keyword_ahead(1, &[kw::Crate]) &&
                 self.look_ahead(2, |t| t != &token::ModSep) // account for `pub(crate::foo)`
             {
                 // `pub(crate)`
@@ -6875,7 +1454,7 @@ impl<'a> Parser<'a> {
                     VisibilityKind::Crate(CrateSugar::PubCrate),
                 );
                 return Ok(vis)
-            } else if self.look_ahead(1, |t| t.is_keyword(keywords::In)) {
+            } else if self.is_keyword_ahead(1, &[kw::In]) {
                 // `pub(in path)`
                 self.bump(); // `(`
                 self.bump(); // `in`
@@ -6887,8 +1466,7 @@ impl<'a> Parser<'a> {
                 });
                 return Ok(vis)
             } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren)) &&
-                      self.look_ahead(1, |t| t.is_keyword(keywords::Super) ||
-                                             t.is_keyword(keywords::SelfLower))
+                      self.is_keyword_ahead(1, &[kw::Super, kw::SelfLower])
             {
                 // `pub(self)` or `pub(super)`
                 self.bump(); // `(`
@@ -6911,665 +1489,44 @@ impl<'a> Parser<'a> {
                 let sp = path.span;
                 let help_msg = format!("make this visible only to module `{}` with `in`", path);
                 self.expect(&token::CloseDelim(token::Paren))?;  // `)`
-                let mut err = struct_span_err!(self.sess.span_diagnostic, sp, E0704, "{}", msg);
-                err.help(suggestion);
-                err.span_suggestion(
-                    sp, &help_msg, format!("in {}", path), Applicability::MachineApplicable
-                );
-                err.emit();  // emit diagnostic, but continue with public visibility
-            }
-        }
-
-        Ok(respan(lo, VisibilityKind::Public))
-    }
-
-    /// Parses defaultness (i.e., `default` or nothing).
-    fn parse_defaultness(&mut self) -> Defaultness {
-        // `pub` is included for better error messages
-        if self.check_keyword(keywords::Default) &&
-           self.look_ahead(1, |t| t.is_keyword(keywords::Impl) ||
-                                  t.is_keyword(keywords::Const) ||
-                                  t.is_keyword(keywords::Fn) ||
-                                  t.is_keyword(keywords::Unsafe) ||
-                                  t.is_keyword(keywords::Extern) ||
-                                  t.is_keyword(keywords::Type) ||
-                                  t.is_keyword(keywords::Pub)) {
-            self.bump(); // `default`
-            Defaultness::Default
-        } else {
-            Defaultness::Final
-        }
-    }
-
-    /// Given a termination token, parses all of the items in a module.
-    fn parse_mod_items(&mut self, term: &token::Token, 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.span, "expected item");
-                return Err(err);
-            }
-        }
-
-        let hi = if self.span.is_dummy() {
-            inner_lo
-        } else {
-            self.prev_span
-        };
-
-        Ok(ast::Mod {
-            inner: inner_lo.to(hi),
-            items,
-            inline: true
-        })
-    }
-
-    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() }?;
-        self.expect(&token::Colon)?;
-        let ty = self.parse_ty()?;
-        self.expect(&token::Eq)?;
-        let e = self.parse_expr()?;
-        self.expect(&token::Semi)?;
-        let item = match m {
-            Some(m) => ItemKind::Static(ty, m, e),
-            None => ItemKind::Const(ty, e),
-        };
-        Ok((id, item, None))
-    }
-
-    /// Parse a `mod <foo> { ... }` or `mod <foo>;` item
-    fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
-        let (in_cfg, outer_attrs) = {
-            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.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, warn } =
-                    self.submod_path(id, &outer_attrs, id_span)?;
-                let (module, mut attrs) =
-                    self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?;
-                // Record that we fetched the mod from an external file
-                if warn {
-                    let attr = Attribute {
-                        id: attr::mk_attr_id(),
-                        style: ast::AttrStyle::Outer,
-                        path: ast::Path::from_ident(
-                            Ident::with_empty_ctxt(sym::warn_directory_ownership)),
-                        tokens: TokenStream::empty(),
-                        is_sugared_doc: false,
-                        span: syntax_pos::DUMMY_SP,
-                    };
-                    attr::mark_known(&attr);
-                    attrs.push(attr);
-                }
-                Ok((id, ItemKind::Mod(module), Some(attrs)))
-            } else {
-                let placeholder = ast::Mod {
-                    inner: syntax_pos::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.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)))
-        }
-    }
-
-    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());
-        }
-    }
-
-    pub 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 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.as_str(), 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),
-                },
-                warn: false,
-            }),
-            (false, true) => Ok(ModulePathSuccess {
-                path: secondary_path,
-                directory_ownership: DirectoryOwnership::Owned {
-                    relative: None,
-                },
-                warn: false,
-            }),
-            (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,
-        }
-    }
-
-    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(true),
-                },
-                path,
-                warn: false,
-            });
-        }
-
-        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(warn) => {
-                if warn {
-                    if let Ok(result) = paths.result {
-                        return Ok(ModulePathSuccess { warn: true, ..result });
-                    }
-                }
-                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)
-            }
-        }
-    }
-
-    /// 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, (ast::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.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))
-    }
-
-    /// Parses a function declaration from a foreign module.
-    fn parse_item_foreign_fn(&mut self, vis: ast::Visibility, lo: Span, attrs: Vec<Attribute>)
-                             -> PResult<'a, ForeignItem> {
-        self.expect_keyword(keywords::Fn)?;
-
-        let (ident, mut generics) = self.parse_fn_header()?;
-        let decl = self.parse_fn_decl(true)?;
-        generics.where_clause = self.parse_where_clause()?;
-        let hi = self.span;
-        self.expect(&token::Semi)?;
-        Ok(ast::ForeignItem {
-            ident,
-            attrs,
-            node: ForeignItemKind::Fn(decl, generics),
-            id: ast::DUMMY_NODE_ID,
-            span: lo.to(hi),
-            vis,
-        })
-    }
-
-    /// 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.span;
-        self.expect(&token::Semi)?;
-        Ok(ForeignItem {
-            ident,
-            attrs,
-            node: ForeignItemKind::Static(ty, mutbl),
-            id: ast::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(keywords::Type)?;
-
-        let ident = self.parse_ident()?;
-        let hi = self.span;
-        self.expect(&token::Semi)?;
-        Ok(ast::ForeignItem {
-            ident: ident,
-            attrs: attrs,
-            node: ForeignItemKind::Ty,
-            id: ast::DUMMY_NODE_ID,
-            span: lo.to(hi),
-            vis: vis
-        })
-    }
-
-    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(keywords::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::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(&fixed_name).with_span_pos(fixed_name_sp);
-
-            let mut err = self.struct_span_err(fixed_name_sp, error_msg);
-            err.span_label(fixed_name_sp, "dash-separated idents are not valid");
-            err.multipart_suggestion(
-                suggestion_msg,
-                replacement,
-                Applicability::MachineApplicable,
-            );
-            err.emit();
-        }
-        Ok(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(&token::Semi)?;
-
-        let span = lo.to(self.prev_span);
-        Ok(self.mk_item(span, item_name, ItemKind::ExternCrate(orig_name), visibility, attrs))
-    }
-
-    /// 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,
-                              opt_abi: Option<Abi>,
-                              visibility: Visibility,
-                              mut attrs: Vec<Attribute>)
-                              -> PResult<'a, P<Item>> {
-        self.expect(&token::OpenDelim(token::Brace))?;
-
-        let abi = opt_abi.unwrap_or(Abi::C);
-
-        attrs.extend(self.parse_inner_attributes()?);
-
-        let mut foreign_items = vec![];
-        while !self.eat(&token::CloseDelim(token::Brace)) {
-            foreign_items.push(self.parse_foreign_item()?);
-        }
-
-        let prev_span = self.prev_span;
-        let m = ast::ForeignMod {
-            abi,
-            items: foreign_items
-        };
-        let invalid = keywords::Invalid.ident();
-        Ok(self.mk_item(lo.to(prev_span), invalid, ItemKind::ForeignMod(m), visibility, attrs))
-    }
-
-    /// Parses `type Foo = Bar;`
-    /// or
-    /// `existential type Foo: Bar;`
-    /// or
-    /// `return `None``
-    /// without modifying the parser state.
-    fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, ast::Generics)>> {
-        // This parses the grammar:
-        //     Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
-        if self.check_keyword(keywords::Type) ||
-           self.check_keyword(keywords::Existential) &&
-                self.look_ahead(1, |t| t.is_keyword(keywords::Type)) {
-            let existential = self.eat_keyword(keywords::Existential);
-            assert!(self.eat_keyword(keywords::Type));
-            Some(self.parse_existential_or_alias(existential))
-        } else {
-            None
-        }
-    }
-
-    /// Parses a type alias or existential type.
-    fn parse_existential_or_alias(
-        &mut self,
-        existential: bool,
-    ) -> PResult<'a, (Ident, AliasKind, ast::Generics)> {
-        let ident = self.parse_ident()?;
-        let mut tps = self.parse_generics()?;
-        tps.where_clause = self.parse_where_clause()?;
-        let alias = if existential {
-            self.expect(&token::Colon)?;
-            let bounds = self.parse_generic_bounds(Some(self.prev_span))?;
-            AliasKind::Existential(bounds)
-        } else {
-            self.expect(&token::Eq)?;
-            let ty = self.parse_ty()?;
-            AliasKind::Weak(ty)
-        };
-        self.expect(&token::Semi)?;
-        Ok((ident, alias, tps))
-    }
-
-    /// Parses the part of an enum declaration following the `{`.
-    fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<'a, EnumDef> {
-        let mut variants = Vec::new();
-        let mut all_nullary = true;
-        let mut any_disr = vec![];
-        while self.token != token::CloseDelim(token::Brace) {
-            let variant_attrs = self.parse_outer_attributes()?;
-            let vlo = self.span;
-
-            let struct_def;
-            let mut disr_expr = None;
-            self.eat_bad_pub();
-            let ident = self.parse_ident()?;
-            if self.check(&token::OpenDelim(token::Brace)) {
-                // Parse a struct variant.
-                all_nullary = false;
-                let (fields, recovered) = self.parse_record_struct_body()?;
-                struct_def = VariantData::Struct(fields, recovered);
-            } else if self.check(&token::OpenDelim(token::Paren)) {
-                all_nullary = false;
-                struct_def = VariantData::Tuple(
-                    self.parse_tuple_struct_body()?,
-                    ast::DUMMY_NODE_ID,
-                );
-            } else if self.eat(&token::Eq) {
-                disr_expr = Some(AnonConst {
-                    id: ast::DUMMY_NODE_ID,
-                    value: self.parse_expr()?,
-                });
-                if let Some(sp) = disr_expr.as_ref().map(|c| c.value.span) {
-                    any_disr.push(sp);
-                }
-                struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
-            } else {
-                struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
-            }
-
-            let vr = ast::Variant_ {
-                ident,
-                id: ast::DUMMY_NODE_ID,
-                attrs: variant_attrs,
-                data: struct_def,
-                disr_expr,
-            };
-            variants.push(respan(vlo.to(self.prev_span), 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);
-                    let mut err = self.struct_span_err(sp, "missing comma");
-                    err.span_suggestion_short(
+                struct_span_err!(self.sess.span_diagnostic, sp, E0704, "{}", msg)
+                    .help(suggestion)
+                    .span_suggestion(
                         sp,
-                        "missing comma",
-                        ",".to_owned(),
-                        Applicability::MaybeIncorrect,
-                    );
-                    err.emit();
-                } else {
-                    break;
-                }
-            }
-        }
-        self.expect(&token::CloseDelim(token::Brace))?;
-        if !any_disr.is_empty() && !all_nullary {
-            let mut err = self.struct_span_err(
-                any_disr.clone(),
-                "discriminator values can only be used with a field-less enum",
-            );
-            for sp in any_disr {
-                err.span_label(sp, "only valid in field-less enums");
+                        &help_msg,
+                        format!("in {}", path),
+                        Applicability::MachineApplicable,
+                    )
+                    .emit();  // emit diagnostic, but continue with public visibility
             }
-            err.emit();
         }
 
-        Ok(ast::EnumDef { variants })
-    }
-
-    /// 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))
+        Ok(respan(lo, VisibilityKind::Public))
     }
 
     /// Parses a string as an ABI spec on an extern type or module. Consumes
     /// the `extern` keyword, if one is found.
     fn parse_opt_abi(&mut self) -> PResult<'a, Option<Abi>> {
-        match self.token {
-            token::Literal(token::Str_(s), suf) | token::Literal(token::StrRaw(s, _), suf) => {
-                let sp = self.span;
-                self.expect_no_suffix(sp, "an ABI spec", suf);
+        match self.token.kind {
+            token::Literal(token::Lit { kind: token::Str, symbol, suffix }) |
+            token::Literal(token::Lit { kind: token::StrRaw(..), symbol, suffix }) => {
+                let sp = self.token.span;
+                self.expect_no_suffix(sp, "an ABI spec", suffix);
                 self.bump();
-                match abi::lookup(&s.as_str()) {
+                match abi::lookup(&symbol.as_str()) {
                     Some(abi) => Ok(Some(abi)),
                     None => {
                         let prev_span = self.prev_span;
-                        let mut err = struct_span_err!(
+                        struct_span_err!(
                             self.sess.span_diagnostic,
                             prev_span,
                             E0703,
                             "invalid ABI: found `{}`",
-                            s);
-                        err.span_label(prev_span, "invalid ABI");
-                        err.help(&format!("valid ABIs: {}", abi::all_names().join(", ")));
-                        err.emit();
+                            symbol
+                        )
+                        .span_label(prev_span, "invalid ABI")
+                        .help(&format!("valid ABIs: {}", abi::all_names().join(", ")))
+                        .emit();
                         Ok(None)
                     }
                 }
@@ -7579,640 +1536,16 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn is_static_global(&mut self) -> bool {
-        if self.check_keyword(keywords::Static) {
-            // Check if this could be a closure
-            !self.look_ahead(1, |token| {
-                if token.is_keyword(keywords::Move) {
-                    return true;
-                }
-                match *token {
-                    token::BinOp(token::Or) | token::OrOr => true,
-                    _ => false,
-                }
-            })
-        } else {
-            false
-        }
-    }
-
-    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.span;
-
-        let visibility = self.parse_visibility(false)?;
-
-        if self.eat_keyword(keywords::Use) {
-            // USE ITEM
-            let item_ = ItemKind::Use(P(self.parse_use_tree()?));
-            self.expect(&token::Semi)?;
-
-            let span = lo.to(self.prev_span);
-            let item = self.mk_item(span, keywords::Invalid.ident(), item_, visibility, attrs);
-            return Ok(Some(item));
-        }
-
-        if self.eat_keyword(keywords::Extern) {
-            if self.eat_keyword(keywords::Crate) {
-                return Ok(Some(self.parse_item_extern_crate(lo, visibility, attrs)?));
-            }
-
-            let opt_abi = self.parse_opt_abi()?;
-
-            if self.eat_keyword(keywords::Fn) {
-                // EXTERN FUNCTION ITEM
-                let fn_span = self.prev_span;
-                let abi = opt_abi.unwrap_or(Abi::C);
-                let (ident, item_, extra_attrs) =
-                    self.parse_item_fn(Unsafety::Normal,
-                                       respan(fn_span, IsAsync::NotAsync),
-                                       respan(fn_span, Constness::NotConst),
-                                       abi)?;
-                let prev_span = self.prev_span;
-                let item = self.mk_item(lo.to(prev_span),
-                                        ident,
-                                        item_,
-                                        visibility,
-                                        maybe_append(attrs, extra_attrs));
-                return Ok(Some(item));
-            } else if self.check(&token::OpenDelim(token::Brace)) {
-                return Ok(Some(self.parse_item_foreign_mod(lo, opt_abi, visibility, attrs)?));
-            }
-
-            self.unexpected()?;
-        }
-
-        if self.is_static_global() {
-            self.bump();
-            // STATIC ITEM
-            let m = if self.eat_keyword(keywords::Mut) {
-                Mutability::Mutable
-            } else {
-                Mutability::Immutable
-            };
-            let (ident, item_, extra_attrs) = self.parse_item_const(Some(m))?;
-            let prev_span = self.prev_span;
-            let item = self.mk_item(lo.to(prev_span),
-                                    ident,
-                                    item_,
-                                    visibility,
-                                    maybe_append(attrs, extra_attrs));
-            return Ok(Some(item));
-        }
-        if self.eat_keyword(keywords::Const) {
-            let const_span = self.prev_span;
-            if self.check_keyword(keywords::Fn)
-                || (self.check_keyword(keywords::Unsafe)
-                    && self.look_ahead(1, |t| t.is_keyword(keywords::Fn))) {
-                // CONST FUNCTION ITEM
-                let unsafety = self.parse_unsafety();
-                self.bump();
-                let (ident, item_, extra_attrs) =
-                    self.parse_item_fn(unsafety,
-                                       respan(const_span, IsAsync::NotAsync),
-                                       respan(const_span, Constness::Const),
-                                       Abi::Rust)?;
-                let prev_span = self.prev_span;
-                let item = self.mk_item(lo.to(prev_span),
-                                        ident,
-                                        item_,
-                                        visibility,
-                                        maybe_append(attrs, extra_attrs));
-                return Ok(Some(item));
-            }
-
-            // CONST ITEM
-            if self.eat_keyword(keywords::Mut) {
-                let prev_span = self.prev_span;
-                let mut err = self.diagnostic()
-                    .struct_span_err(prev_span, "const globals cannot be mutable");
-                err.span_label(prev_span, "cannot be mutable");
-                err.span_suggestion(
-                    const_span,
-                    "you might want to declare a static instead",
-                    "static".to_owned(),
-                    Applicability::MaybeIncorrect,
-                );
-                err.emit();
-            }
-            let (ident, item_, extra_attrs) = self.parse_item_const(None)?;
-            let prev_span = self.prev_span;
-            let item = self.mk_item(lo.to(prev_span),
-                                    ident,
-                                    item_,
-                                    visibility,
-                                    maybe_append(attrs, extra_attrs));
-            return Ok(Some(item));
-        }
-
-        // `unsafe async fn` or `async fn`
-        if (
-            self.check_keyword(keywords::Unsafe) &&
-            self.look_ahead(1, |t| t.is_keyword(keywords::Async))
-        ) || (
-            self.check_keyword(keywords::Async) &&
-            self.look_ahead(1, |t| t.is_keyword(keywords::Fn))
-        )
-        {
-            // ASYNC FUNCTION ITEM
-            let unsafety = self.parse_unsafety();
-            self.expect_keyword(keywords::Async)?;
-            let async_span = self.prev_span;
-            self.expect_keyword(keywords::Fn)?;
-            let fn_span = self.prev_span;
-            let (ident, item_, extra_attrs) =
-                self.parse_item_fn(unsafety,
-                                   respan(async_span, IsAsync::Async {
-                                       closure_id: ast::DUMMY_NODE_ID,
-                                       return_impl_trait_id: ast::DUMMY_NODE_ID,
-                                       arguments: Vec::new(),
-                                   }),
-                                   respan(fn_span, Constness::NotConst),
-                                   Abi::Rust)?;
-            let prev_span = self.prev_span;
-            let item = self.mk_item(lo.to(prev_span),
-                                    ident,
-                                    item_,
-                                    visibility,
-                                    maybe_append(attrs, extra_attrs));
-            if self.span.rust_2015() {
-                self.diagnostic().struct_span_err_with_code(
+    /// 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();
-            }
-            return Ok(Some(item));
-        }
-        if self.check_keyword(keywords::Unsafe) &&
-            (self.look_ahead(1, |t| t.is_keyword(keywords::Trait)) ||
-            self.look_ahead(1, |t| t.is_keyword(keywords::Auto)))
-        {
-            // UNSAFE TRAIT ITEM
-            self.bump(); // `unsafe`
-            let is_auto = if self.eat_keyword(keywords::Trait) {
-                IsAuto::No
-            } else {
-                self.expect_keyword(keywords::Auto)?;
-                self.expect_keyword(keywords::Trait)?;
-                IsAuto::Yes
-            };
-            let (ident, item_, extra_attrs) =
-                self.parse_item_trait(is_auto, Unsafety::Unsafe)?;
-            let prev_span = self.prev_span;
-            let item = self.mk_item(lo.to(prev_span),
-                                    ident,
-                                    item_,
-                                    visibility,
-                                    maybe_append(attrs, extra_attrs));
-            return Ok(Some(item));
-        }
-        if self.check_keyword(keywords::Impl) ||
-           self.check_keyword(keywords::Unsafe) &&
-                self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) ||
-           self.check_keyword(keywords::Default) &&
-                self.look_ahead(1, |t| t.is_keyword(keywords::Impl)) ||
-           self.check_keyword(keywords::Default) &&
-                self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe)) {
-            // IMPL ITEM
-            let defaultness = self.parse_defaultness();
-            let unsafety = self.parse_unsafety();
-            self.expect_keyword(keywords::Impl)?;
-            let (ident, item, extra_attrs) = self.parse_item_impl(unsafety, defaultness)?;
-            let span = lo.to(self.prev_span);
-            return Ok(Some(self.mk_item(span, ident, item, visibility,
-                                        maybe_append(attrs, extra_attrs))));
-        }
-        if self.check_keyword(keywords::Fn) {
-            // FUNCTION ITEM
-            self.bump();
-            let fn_span = self.prev_span;
-            let (ident, item_, extra_attrs) =
-                self.parse_item_fn(Unsafety::Normal,
-                                   respan(fn_span, IsAsync::NotAsync),
-                                   respan(fn_span, Constness::NotConst),
-                                   Abi::Rust)?;
-            let prev_span = self.prev_span;
-            let item = self.mk_item(lo.to(prev_span),
-                                    ident,
-                                    item_,
-                                    visibility,
-                                    maybe_append(attrs, extra_attrs));
-            return Ok(Some(item));
-        }
-        if self.check_keyword(keywords::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 = if self.eat_keyword(keywords::Extern) {
-                self.parse_opt_abi()?.unwrap_or(Abi::C)
-            } else {
-                Abi::Rust
-            };
-            self.expect_keyword(keywords::Fn)?;
-            let fn_span = self.prev_span;
-            let (ident, item_, extra_attrs) =
-                self.parse_item_fn(Unsafety::Unsafe,
-                                   respan(fn_span, IsAsync::NotAsync),
-                                   respan(fn_span, Constness::NotConst),
-                                   abi)?;
-            let prev_span = self.prev_span;
-            let item = self.mk_item(lo.to(prev_span),
-                                    ident,
-                                    item_,
-                                    visibility,
-                                    maybe_append(attrs, extra_attrs));
-            return Ok(Some(item));
-        }
-        if self.eat_keyword(keywords::Mod) {
-            // MODULE ITEM
-            let (ident, item_, extra_attrs) =
-                self.parse_item_mod(&attrs[..])?;
-            let prev_span = self.prev_span;
-            let item = self.mk_item(lo.to(prev_span),
-                                    ident,
-                                    item_,
-                                    visibility,
-                                    maybe_append(attrs, extra_attrs));
-            return Ok(Some(item));
-        }
-        if let Some(type_) = self.eat_type() {
-            let (ident, alias, generics) = type_?;
-            // TYPE ITEM
-            let item_ = match alias {
-                AliasKind::Weak(ty) => ItemKind::Ty(ty, generics),
-                AliasKind::Existential(bounds) => ItemKind::Existential(bounds, generics),
-            };
-            let prev_span = self.prev_span;
-            let item = self.mk_item(lo.to(prev_span),
-                                    ident,
-                                    item_,
-                                    visibility,
-                                    attrs);
-            return Ok(Some(item));
-        }
-        if self.eat_keyword(keywords::Enum) {
-            // ENUM ITEM
-            let (ident, item_, extra_attrs) = self.parse_item_enum()?;
-            let prev_span = self.prev_span;
-            let item = self.mk_item(lo.to(prev_span),
-                                    ident,
-                                    item_,
-                                    visibility,
-                                    maybe_append(attrs, extra_attrs));
-            return Ok(Some(item));
-        }
-        if self.check_keyword(keywords::Trait)
-            || (self.check_keyword(keywords::Auto)
-                && self.look_ahead(1, |t| t.is_keyword(keywords::Trait)))
-        {
-            let is_auto = if self.eat_keyword(keywords::Trait) {
-                IsAuto::No
-            } else {
-                self.expect_keyword(keywords::Auto)?;
-                self.expect_keyword(keywords::Trait)?;
-                IsAuto::Yes
-            };
-            // TRAIT ITEM
-            let (ident, item_, extra_attrs) =
-                self.parse_item_trait(is_auto, Unsafety::Normal)?;
-            let prev_span = self.prev_span;
-            let item = self.mk_item(lo.to(prev_span),
-                                    ident,
-                                    item_,
-                                    visibility,
-                                    maybe_append(attrs, extra_attrs));
-            return Ok(Some(item));
-        }
-        if self.eat_keyword(keywords::Struct) {
-            // STRUCT ITEM
-            let (ident, item_, extra_attrs) = self.parse_item_struct()?;
-            let prev_span = self.prev_span;
-            let item = self.mk_item(lo.to(prev_span),
-                                    ident,
-                                    item_,
-                                    visibility,
-                                    maybe_append(attrs, extra_attrs));
-            return Ok(Some(item));
-        }
-        if self.is_union_item() {
-            // UNION ITEM
-            self.bump();
-            let (ident, item_, extra_attrs) = self.parse_item_union()?;
-            let prev_span = self.prev_span;
-            let item = self.mk_item(lo.to(prev_span),
-                                    ident,
-                                    item_,
-                                    visibility,
-                                    maybe_append(attrs, extra_attrs));
-            return Ok(Some(item));
-        }
-        if let Some(macro_def) = self.eat_macro_def(&attrs, &visibility, 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 visibility.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.span);
-            let full_sp = self.prev_span.to(self.span);
-            let ident_sp = self.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 = if let Ok(Some(_)) = self.parse_self_arg() {
-                    "method"
-                } else {
-                    "function"
-                };
-                self.consume_block(token::Paren);
-                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);
-                    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.sess.source_map().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)) {
-                    if let Ok(Some(_)) = self.parse_self_arg() {
-                        ("fn", "method", false)
-                    } else {
-                        ("fn", "function", 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, visibility)
-    }
-
-    /// Parses a foreign item.
-    crate fn parse_foreign_item(&mut self) -> PResult<'a, ForeignItem> {
-        maybe_whole!(self, NtForeignItem, |ni| ni);
-
-        let attrs = self.parse_outer_attributes()?;
-        let lo = self.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(keywords::Static) || self.token.is_keyword(keywords::Const) {
-            if self.token.is_keyword(keywords::Const) {
-                self.diagnostic()
-                    .struct_span_err(self.span, "extern items cannot be `const`")
-                    .span_suggestion(
-                        self.span,
-                        "try using a static value",
-                        "static".to_owned(),
-                        Applicability::MachineApplicable
-                    ).emit();
-            }
-            self.bump(); // `static` or `const`
-            return Ok(self.parse_item_foreign_static(visibility, lo, attrs)?);
-        }
-        // FOREIGN FUNCTION ITEM
-        if self.check_keyword(keywords::Fn) {
-            return Ok(self.parse_item_foreign_fn(visibility, lo, attrs)?);
-        }
-        // FOREIGN TYPE ITEM
-        if self.check_keyword(keywords::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: keywords::Invalid.ident(),
-                        span: lo.to(self.prev_span),
-                        id: ast::DUMMY_NODE_ID,
-                        attrs,
-                        vis: visibility,
-                        node: ForeignItemKind::Macro(mac),
-                    }
                 )
-            }
-            None => {
-                if !attrs.is_empty()  {
-                    self.expected_item_err(&attrs)?;
-                }
-
-                self.unexpected()
-            }
-        }
-    }
-
-    /// 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.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.span;
-
-            // item macro.
-            let pth = self.parse_path(PathStyle::Mod)?;
-            self.expect(&token::Not)?;
-
-            // a 'special' identifier (like what `macro_rules!` uses)
-            // is optional. We should eventually unify invoc syntax
-            // and remove this.
-            let id = if self.token.is_ident() {
-                self.parse_ident()?
-            } else {
-                keywords::Invalid.ident() // no special identifier
-            };
-            // eat a matched-delimiter token tree:
-            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 = respan(mac_lo.to(hi), Mac_ { path: pth, tts, delim });
-            let item = self.mk_item(lo.to(hi), id, 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)
-    }
-
-    /// 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.span.rust_2015()) {
-            let prev_span = self.prev_span;
-            let lo = self.span;
-            let pth = self.parse_path(PathStyle::Mod)?;
-
-            if pth.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(&token::Semi)?;
-            }
-
-            Ok(Some(respan(lo.to(self.prev_span), Mac_ { path: pth, tts, delim })))
-        } else {
-            Ok(None)
+                .emit();
         }
     }
 
@@ -8223,7 +1556,7 @@ impl<'a> Parser<'a> {
         let mut tokens = Vec::new();
         let prev_collecting = match self.token_cursor.frame.last_token {
             LastToken::Collecting(ref mut list) => {
-                Some(mem::replace(list, Vec::new()))
+                Some(mem::take(list))
             }
             LastToken::Was(ref mut last) => {
                 tokens.extend(last.take());
@@ -8235,14 +1568,27 @@ impl<'a> Parser<'a> {
         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::new(vec![])));
         } 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::replace(v, Vec::new()),
-            LastToken::Was(_) => panic!("our vector went away?"),
+            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::new(vec![])));
+            }
         };
 
         // If we're not at EOF our current token wasn't actually consumed by
@@ -8272,11 +1618,6 @@ impl<'a> Parser<'a> {
         Ok((ret?, TokenStream::new(collected_tokens)))
     }
 
-    pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> {
-        let attrs = self.parse_outer_attributes()?;
-        self.parse_item_(attrs, true, false)
-    }
-
     /// `::{` or `::*`
     fn is_import_coupler(&mut self) -> bool {
         self.check(&token::ModSep) &&
@@ -8284,89 +1625,12 @@ impl<'a> Parser<'a> {
                                    *t == token::BinOp(token::Star))
     }
 
-    /// 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.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.span.ctxt();
-            if self.eat(&token::ModSep) {
-                prefix.segments.push(
-                    PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt))
-                );
-            }
-
-            if self.eat(&token::BinOp(token::Star)) {
-                UseTreeKind::Glob
-            } else {
-                UseTreeKind::Nested(self.parse_use_tree_list()?)
-            }
-        } 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) {
-                if self.eat(&token::BinOp(token::Star)) {
-                    UseTreeKind::Glob
-                } else {
-                    UseTreeKind::Nested(self.parse_use_tree_list()?)
-                }
-            } else {
-                UseTreeKind::Simple(self.parse_rename()?, ast::DUMMY_NODE_ID, ast::DUMMY_NODE_ID)
-            }
-        };
-
-        Ok(UseTree { prefix, kind, span: lo.to(self.prev_span) })
-    }
-
-    /// 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_unspanned_seq(&token::OpenDelim(token::Brace),
-                                 &token::CloseDelim(token::Brace),
-                                 SeqSep::trailing_allowed(token::Comma), |this| {
-            Ok((this.parse_use_tree()?, ast::DUMMY_NODE_ID))
-        })
-    }
-
-    fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
-        if self.eat_keyword(keywords::As) {
-            self.parse_ident_or_underscore().map(Some)
-        } else {
-            Ok(None)
-        }
-    }
-
-    /// 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.span;
-        let krate = Ok(ast::Crate {
-            attrs: self.parse_inner_attributes()?,
-            module: self.parse_mod_items(&token::Eof, lo)?,
-            span: lo.to(self.span),
-        });
-        krate
-    }
-
     pub fn parse_optional_str(&mut self) -> Option<(Symbol, ast::StrStyle, Option<ast::Name>)> {
-        let ret = match self.token {
-            token::Literal(token::Str_(s), suf) => (s, ast::StrStyle::Cooked, suf),
-            token::Literal(token::StrRaw(s, n), suf) => (s, ast::StrStyle::Raw(n), suf),
+        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();
@@ -8383,7 +1647,7 @@ impl<'a> Parser<'a> {
             _ => {
                 let msg = "expected string literal";
                 let mut err = self.fatal(msg);
-                err.span_label(self.span, msg);
+                err.span_label(self.token.span, msg);
                 Err(err)
             }
         }
@@ -8407,122 +1671,13 @@ impl<'a> Parser<'a> {
             Applicability::MaybeIncorrect,
         ).emit();
     }
-
-    /// When lowering a `async fn` to the HIR, we need to move all of the arguments of the function
-    /// into the generated closure so that they are dropped when the future is polled and not when
-    /// it is created.
-    ///
-    /// The arguments of the function are replaced in HIR lowering with the arguments created by
-    /// this function and the statements created here are inserted at the top of the closure body.
-    fn construct_async_arguments(&mut self, asyncness: &mut Spanned<IsAsync>, decl: &mut FnDecl) {
-        // FIXME(davidtwco): This function should really live in the HIR lowering but because
-        // the types constructed here need to be used in parts of resolve so that the correct
-        // locals are considered upvars, it is currently easier for it to live here in the parser,
-        // where it can be constructed once.
-        if let IsAsync::Async { ref mut arguments, .. } = asyncness.node {
-            for (index, input) in decl.inputs.iter_mut().enumerate() {
-                let id = ast::DUMMY_NODE_ID;
-                let span = input.pat.span;
-
-                // Construct a name for our temporary argument.
-                let name = format!("__arg{}", index);
-                let ident = Ident::from_str(&name).gensym();
-
-                // Check if this is a ident pattern, if so, we can optimize and avoid adding a
-                // `let <pat> = __argN;` statement, instead just adding a `let <pat> = <pat>;`
-                // statement.
-                let (binding_mode, ident, is_simple_pattern) = match input.pat.node {
-                    PatKind::Ident(binding_mode @ BindingMode::ByValue(_), ident, _) => {
-                        // Simple patterns like this don't have a generated argument, but they are
-                        // moved into the closure with a statement, so any `mut` bindings on the
-                        // argument will be unused. This binding mode can't be removed, because
-                        // this would affect the input to procedural macros, but they can have
-                        // their span marked as being the result of a compiler desugaring so
-                        // that they aren't linted against.
-                        input.pat.span = self.sess.source_map().mark_span_with_reason(
-                            CompilerDesugaringKind::Async, span, None);
-
-                        (binding_mode, ident, true)
-                    }
-                    _ => (BindingMode::ByValue(Mutability::Mutable), ident, false),
-                };
-
-                // Construct an argument representing `__argN: <ty>` to replace the argument of the
-                // async function if it isn't a simple pattern.
-                let arg = if is_simple_pattern {
-                    None
-                } else {
-                    Some(Arg {
-                        ty: input.ty.clone(),
-                        id,
-                        pat: P(Pat {
-                            id,
-                            node: PatKind::Ident(
-                                BindingMode::ByValue(Mutability::Immutable), ident, None,
-                            ),
-                            span,
-                        }),
-                        source: ArgSource::AsyncFn(input.pat.clone()),
-                    })
-                };
-
-                // Construct a `let __argN = __argN;` statement to insert at the top of the
-                // async closure. This makes sure that the argument is captured by the closure and
-                // that the drop order is correct.
-                let move_local = Local {
-                    pat: P(Pat {
-                        id,
-                        node: PatKind::Ident(binding_mode, ident, None),
-                        span,
-                    }),
-                    // We explicitly do not specify the type for this statement. When the user's
-                    // argument type is `impl Trait` then this would require the
-                    // `impl_trait_in_bindings` feature to also be present for that same type to
-                    // be valid in this binding. At the time of writing (13 Mar 19),
-                    // `impl_trait_in_bindings` is not stable.
-                    ty: None,
-                    init: Some(P(Expr {
-                        id,
-                        node: ExprKind::Path(None, ast::Path {
-                            span,
-                            segments: vec![PathSegment { ident, id, args: None }],
-                        }),
-                        span,
-                        attrs: ThinVec::new(),
-                    })),
-                    id,
-                    span,
-                    attrs: ThinVec::new(),
-                    source: LocalSource::AsyncFn,
-                };
-
-                // Construct a `let <pat> = __argN;` statement to insert at the top of the
-                // async closure if this isn't a simple pattern.
-                let pat_stmt = if is_simple_pattern {
-                    None
-                } else {
-                    Some(Stmt {
-                        id,
-                        node: StmtKind::Local(P(Local {
-                            pat: input.pat.clone(),
-                            ..move_local.clone()
-                        })),
-                        span,
-                    })
-                };
-
-                let move_stmt = Stmt { id, node: StmtKind::Local(P(move_local)), span };
-                arguments.push(AsyncArgument { ident, arg, pat_stmt, move_stmt });
-            }
-        }
-    }
 }
 
 pub fn emit_unclosed_delims(unclosed_delims: &mut Vec<UnmatchedBrace>, handler: &errors::Handler) {
     for unmatched in unclosed_delims.iter() {
         let mut err = handler.struct_span_err(unmatched.found_span, &format!(
             "incorrect close delimiter: `{}`",
-            pprust::token_to_string(&token::Token::CloseDelim(unmatched.found_delim)),
+            pprust::token_kind_to_string(&token::CloseDelim(unmatched.found_delim)),
         ));
         err.span_label(unmatched.found_span, "incorrect close delimiter");
         if let Some(sp) = unmatched.candidate_span {