From 7a30bb1676690596f73659d18959877d993510ae Mon Sep 17 00:00:00 2001
From: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>
Date: Mon, 9 Mar 2020 12:42:33 +0300
Subject: [PATCH] Address review comments

---
 src/librustc_ast/token.rs               | 19 ++++++++++++++-----
 src/librustc_expand/mbe/macro_parser.rs |  5 +----
 src/librustc_parse/parser/expr.rs       | 13 ++++++-------
 src/librustc_parse/parser/item.rs       |  2 +-
 4 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/src/librustc_ast/token.rs b/src/librustc_ast/token.rs
index b022d969deccb..b67b7d346f756 100644
--- a/src/librustc_ast/token.rs
+++ b/src/librustc_ast/token.rs
@@ -225,8 +225,15 @@ pub enum TokenKind {
     /* Literals */
     Literal(Lit),
 
-    /* Name components */
+    /// Identifier token.
+    /// Do not forget about `NtIdent` when you want to match on identifiers.
+    /// It's recommended to use `Token::(ident,uninterpolate,uninterpolated_span)` to
+    /// treat regular and interpolated identifiers in the same way.
     Ident(ast::Name, /* is_raw */ bool),
+    /// Lifetime identifier token.
+    /// Do not forget about `NtLifetime` when you want to match on lifetime identifiers.
+    /// It's recommended to use `Token::(lifetime,uninterpolate,uninterpolated_span)` to
+    /// treat regular and interpolated lifetime identifiers in the same way.
     Lifetime(ast::Name),
 
     Interpolated(Lrc<Nonterminal>),
@@ -328,11 +335,12 @@ impl Token {
         mem::replace(self, Token::dummy())
     }
 
-    /// For interpolated tokens returns a span of the fragment to which the interpolated
-    /// token refers, for all other tokens this is just a regular span.
+    /// For interpolated tokens, returns a span of the fragment to which the interpolated
+    /// token refers. For all other tokens this is just a regular span.
     /// It is particularly important to use this for identifiers and lifetimes
-    /// for which spans affect name resolution. This also includes edition checks
-    /// for edition-specific keyword identifiers.
+    /// for which spans affect name resolution and edition checks.
+    /// Note that keywords are also identifiers, so they should use this
+    /// if they keep spans or perform edition checks.
     pub fn uninterpolated_span(&self) -> Span {
         match &self.kind {
             Interpolated(nt) => nt.span(),
@@ -453,6 +461,7 @@ impl Token {
         }
     }
 
+    // A convenience function for matching on identifiers during parsing.
     // Turns interpolated identifier (`$i: ident`) or lifetime (`$l: lifetime`) token
     // into the regular identifier or lifetime token it refers to,
     // otherwise returns the original token.
diff --git a/src/librustc_expand/mbe/macro_parser.rs b/src/librustc_expand/mbe/macro_parser.rs
index efba3a8ccb1e6..6d4d7f5b4f394 100644
--- a/src/librustc_expand/mbe/macro_parser.rs
+++ b/src/librustc_expand/mbe/macro_parser.rs
@@ -751,10 +751,7 @@ pub(super) fn parse_tt(parser: &mut Cow<'_, Parser<'_>>, ms: &[TokenTree]) -> Na
 /// The token is an identifier, but not `_`.
 /// We prohibit passing `_` to macros expecting `ident` for now.
 fn get_macro_ident(token: &Token) -> Option<(Ident, bool)> {
-    match token.ident() {
-        Some((ident, is_raw)) if ident.name != kw::Underscore => Some((ident, is_raw)),
-        _ => None,
-    }
+    token.ident().filter(|(ident, _)| ident.name != kw::Underscore)
 }
 
 /// Checks whether a non-terminal may begin with a particular token.
diff --git a/src/librustc_parse/parser/expr.rs b/src/librustc_parse/parser/expr.rs
index d28b9cd968218..bfca9f07f05d5 100644
--- a/src/librustc_parse/parser/expr.rs
+++ b/src/librustc_parse/parser/expr.rs
@@ -97,9 +97,8 @@ impl<'a> Parser<'a> {
         match self.parse_expr() {
             Ok(expr) => Ok(expr),
             Err(mut err) => match self.token.ident() {
-                Some((ident, false))
-                    if ident.name == kw::Underscore
-                        && self.look_ahead(1, |t| t == &token::Comma) =>
+                Some((Ident { name: kw::Underscore, .. }, false))
+                    if self.look_ahead(1, |t| t == &token::Comma) =>
                 {
                     // Special-case handling of `foo(_, _, _)`
                     err.emit();
@@ -333,13 +332,13 @@ impl<'a> Parser<'a> {
     fn check_assoc_op(&self) -> Option<Spanned<AssocOp>> {
         let (op, span) = match (AssocOp::from_token(&self.token), self.token.ident()) {
             (Some(op), _) => (op, self.token.span),
-            (None, Some((ident, false))) if ident.name == sym::and => {
+            (None, Some((Ident { name: sym::and, span }, false))) => {
                 self.error_bad_logical_op("and", "&&", "conjunction");
-                (AssocOp::LAnd, ident.span)
+                (AssocOp::LAnd, span)
             }
-            (None, Some((ident, false))) if ident.name == sym::or => {
+            (None, Some((Ident { name: sym::or, span }, false))) => {
                 self.error_bad_logical_op("or", "||", "disjunction");
-                (AssocOp::LOr, ident.span)
+                (AssocOp::LOr, span)
             }
             _ => return None,
         };
diff --git a/src/librustc_parse/parser/item.rs b/src/librustc_parse/parser/item.rs
index bf612bfc0e4a1..126686c8defbf 100644
--- a/src/librustc_parse/parser/item.rs
+++ b/src/librustc_parse/parser/item.rs
@@ -751,7 +751,7 @@ impl<'a> Parser<'a> {
 
     fn parse_ident_or_underscore(&mut self) -> PResult<'a, ast::Ident> {
         match self.token.ident() {
-            Some((ident, false)) if ident.name == kw::Underscore => {
+            Some((ident @ Ident { name: kw::Underscore, .. }, false)) => {
                 self.bump();
                 Ok(ident)
             }