Auto merge of #50307 - petrochenkov:keyhyg2, r=nikomatsakis

Implement edition hygiene for keywords

Determine "keywordness" of an identifier in its hygienic context.
cc https://github.com/rust-lang/rust/pull/49611

I've resurrected `proc` as an Edition-2015-only keyword for testing purposes, but it should probably be buried again. EDIT: `proc` is removed again.

2 files changed, 7 insertions, 45 deletions

diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
index a0434fe6616..bbece1ee5e3 100644
--- a/src/libsyntax/parse/lexer/mod.rs
+++ b/src/libsyntax/parse/lexer/mod.rs
@@ -1128,7 +1128,7 @@ impl<'a> StringReader<'a> {
                 return Ok(self.with_str_from(start, |string| {
                     // FIXME: perform NFKC normalization here. (Issue #2253)
                     let ident = self.mk_ident(string);
-                    if is_raw_ident && (token::is_path_segment_keyword(ident) ||
+                    if is_raw_ident && (ident.is_path_segment_keyword() ||
                                         ident.name == keywords::Underscore.name()) {
                         self.fatal_span_(raw_start, self.pos,
                             &format!("`r#{}` is not currently supported.", ident.name)
diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index a1c056cbb2c..5575614a4d4 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -138,44 +138,6 @@ fn ident_can_begin_type(ident: ast::Ident, is_raw: bool) -> bool {
     ].contains(&ident.name)
 }
 
-pub fn is_path_segment_keyword(id: ast::Ident) -> bool {
-    id.name == keywords::Super.name() ||
-    id.name == keywords::SelfValue.name() ||
-    id.name == keywords::SelfType.name() ||
-    id.name == keywords::Extern.name() ||
-    id.name == keywords::Crate.name() ||
-    id.name == keywords::CrateRoot.name() ||
-    id.name == keywords::DollarCrate.name()
-}
-
-// We see this identifier in a normal identifier position, like variable name or a type.
-// How was it written originally? Did it use the raw form? Let's try to guess.
-pub fn is_raw_guess(ident: ast::Ident) -> bool {
-    ident.name != keywords::Invalid.name() &&
-    is_reserved_ident(ident) && !is_path_segment_keyword(ident)
-}
-
-// Returns true for reserved identifiers used internally for elided lifetimes,
-// unnamed method parameters, crate root module, error recovery etc.
-pub fn is_special_ident(id: ast::Ident) -> bool {
-    id.name <= keywords::Underscore.name()
-}
-
-/// Returns `true` if the token is a keyword used in the language.
-pub fn is_used_keyword(id: ast::Ident) -> bool {
-    id.name >= keywords::As.name() && id.name <= keywords::While.name()
-}
-
-/// Returns `true` if the token is a keyword reserved for possible future use.
-pub fn is_unused_keyword(id: ast::Ident) -> bool {
-    id.name >= keywords::Abstract.name() && id.name <= keywords::Yield.name()
-}
-
-/// Returns `true` if the token is either a special identifier or a keyword.
-pub fn is_reserved_ident(id: ast::Ident) -> bool {
-    is_special_ident(id) || is_used_keyword(id) || is_unused_keyword(id)
-}
-
 #[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Hash, Debug)]
 pub enum Token {
     /* Expression-operator symbols. */
@@ -251,7 +213,7 @@ impl Token {
 
     /// Recovers a `Token` from an `ast::Ident`. This creates a raw identifier if necessary.
     pub fn from_ast_ident(ident: ast::Ident) -> Token {
-        Ident(ident, is_raw_guess(ident))
+        Ident(ident, ident.is_raw_guess())
     }
 
     /// Returns `true` if the token starts with '>'.
@@ -431,7 +393,7 @@ impl Token {
 
     pub fn is_path_segment_keyword(&self) -> bool {
         match self.ident() {
-            Some((id, false)) => is_path_segment_keyword(id),
+            Some((id, false)) => id.is_path_segment_keyword(),
             _ => false,
         }
     }
@@ -440,7 +402,7 @@ impl Token {
     // unnamed method parameters, crate root module, error recovery etc.
     pub fn is_special_ident(&self) -> bool {
         match self.ident() {
-            Some((id, false)) => is_special_ident(id),
+            Some((id, false)) => id.is_special(),
             _ => false,
         }
     }
@@ -448,7 +410,7 @@ impl Token {
     /// Returns `true` if the token is a keyword used in the language.
     pub fn is_used_keyword(&self) -> bool {
         match self.ident() {
-            Some((id, false)) => is_used_keyword(id),
+            Some((id, false)) => id.is_used_keyword(),
             _ => false,
         }
     }
@@ -456,7 +418,7 @@ impl Token {
     /// Returns `true` if the token is a keyword reserved for possible future use.
     pub fn is_unused_keyword(&self) -> bool {
         match self.ident() {
-            Some((id, false)) => is_unused_keyword(id),
+            Some((id, false)) => id.is_unused_keyword(),
             _ => false,
         }
     }
@@ -464,7 +426,7 @@ impl Token {
     /// Returns `true` if the token is either a special identifier or a keyword.
     pub fn is_reserved_ident(&self) -> bool {
         match self.ident() {
-            Some((id, false)) => is_reserved_ident(id),
+            Some((id, false)) => id.is_reserved(),
             _ => false,
         }
     }