Cleanup interfaces of Name, SyntaxContext and Ident

Make sure Name, SyntaxContext and Ident are passed by value
Make sure Idents don't serve as keys (or parts of keys) in maps, Ident comparison is not well defined

src/libsyntax/parse/parser.rs

@@ -4715,7 +4715,7 @@ impl<'a> Parser<'a> {
             (fields, None)
         // Tuple-style struct definition with optional where-clause.
         } else if self.token == token::OpenDelim(token::Paren) {
-            let fields = try!(self.parse_tuple_struct_body(&class_name, &mut generics));
+            let fields = try!(self.parse_tuple_struct_body(class_name, &mut generics));
             (fields, Some(ast::DUMMY_NODE_ID))
         } else {
             let token_str = self.this_token_to_string();
@@ -4750,7 +4750,7 @@ impl<'a> Parser<'a> {
     }
 
     pub fn parse_tuple_struct_body(&mut self,
-                                   class_name: &ast::Ident,
+                                   class_name: ast::Ident,
                                    generics: &mut ast::Generics)
                                    -> PResult<Vec<StructField>> {
         // This is the case where we find `struct Foo<T>(T) where T: Copy;`
@@ -5780,10 +5780,10 @@ impl<'a> Parser<'a> {
                                                  Option<ast::Name>)>> {
         let ret = match self.token {
             token::Literal(token::Str_(s), suf) => {
-                (self.id_to_interned_str(s.ident()), ast::CookedStr, suf)
+                (self.id_to_interned_str(ast::Ident::with_empty_ctxt(s)), ast::CookedStr, suf)
             }
             token::Literal(token::StrRaw(s, n), suf) => {
-                (self.id_to_interned_str(s.ident()), ast::RawStr(n), suf)
+                (self.id_to_interned_str(ast::Ident::with_empty_ctxt(s)), ast::RawStr(n), suf)
             }
             _ => return Ok(None)
         };