Auto merge of #28642 - petrochenkov:name3, r=nrc

This PR removes random remaining `Ident`s outside of libsyntax and performs general cleanup
In particular, interfaces of `Name` and `Ident` are tidied up, `Name`s and `Ident`s being small `Copy` aggregates are always passed to functions by value, and `Ident`s are never used as keys in maps, because `Ident` comparisons are tricky.

Although this PR closes https://github.com/rust-lang/rust/issues/6993 there's still work related to it:
- `Name` can be made `NonZero` to compress numerous `Option<Name>`s and `Option<Ident>`s but it requires const unsafe functions.
- Implementation of `PartialEq` on `Ident` should be eliminated and replaced with explicit hygienic, non-hygienic or member-wise comparisons.
- Finally, large parts of AST can potentially be converted to `Name`s in the same way as HIR to clearly separate identifiers used in hygienic and non-hygienic contexts.

r? @nrc 

1 files changed, 6 insertions, 6 deletions

diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 6643dad6a68..18c6d74d62e 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -35,7 +35,7 @@ use codemap::{CodeMap, Span};
 use diagnostic::SpanHandler;
 use visit;
 use visit::{FnKind, Visitor};
-use parse::token::{self, InternedString};
+use parse::token::InternedString;
 
 use std::ascii::AsciiExt;
 use std::cmp;
@@ -673,7 +673,7 @@ struct MacroVisitor<'a> {
 impl<'a, 'v> Visitor<'v> for MacroVisitor<'a> {
     fn visit_mac(&mut self, mac: &ast::Mac) {
         let path = &mac.node.path;
-        let id = path.segments.last().unwrap().identifier;
+        let name = path.segments.last().unwrap().identifier.name.as_str();
 
         // Issue 22234: If you add a new case here, make sure to also
         // add code to catch the macro during or after expansion.
@@ -683,19 +683,19 @@ impl<'a, 'v> Visitor<'v> for MacroVisitor<'a> {
         // catch uses of these macros within conditionally-compiled
         // code, e.g. `#[cfg]`-guarded functions.
 
-        if id == token::str_to_ident("asm") {
+        if name == "asm" {
             self.context.gate_feature("asm", path.span, EXPLAIN_ASM);
         }
 
-        else if id == token::str_to_ident("log_syntax") {
+        else if name == "log_syntax" {
             self.context.gate_feature("log_syntax", path.span, EXPLAIN_LOG_SYNTAX);
         }
 
-        else if id == token::str_to_ident("trace_macros") {
+        else if name == "trace_macros" {
             self.context.gate_feature("trace_macros", path.span, EXPLAIN_TRACE_MACROS);
         }
 
-        else if id == token::str_to_ident("concat_idents") {
+        else if name == "concat_idents" {
             self.context.gate_feature("concat_idents", path.span, EXPLAIN_CONCAT_IDENTS);
         }
     }