Resurrecting #33135

Started rebasing @sgrif's PR #33135 off of current master. (Well, actually merging it into a new branch based off current master.)

The following files still need to be fixed or at least reviewed:

- `src/libsyntax/ext/tt/macro_parser.rs`: calls `Parser::parse_lifetime`, which doesn't exist anymore
- `src/libsyntax/parse/parser.rs`: @sgrif added an error message to `Parser::parse_lifetime`. Code has since been refactored, so I just took it out for now.
- `src/libsyntax/ext/tt/transcribe.rs`: This code has been refactored bigtime. Not sure whether @sgrif's changes here are still necessary. Took it out for this commit.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index 05368c52d2c..a5766f5601a 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -524,6 +524,7 @@ pub enum Nonterminal {
     NtGenerics(ast::Generics),
     NtWhereClause(ast::WhereClause),
     NtArg(ast::Arg),
+    NtLifetime(ast::Lifetime),
 }
 
 impl fmt::Debug for Nonterminal {
@@ -546,6 +547,7 @@ impl fmt::Debug for Nonterminal {
             NtWhereClause(..) => f.pad("NtWhereClause(..)"),
             NtArg(..) => f.pad("NtArg(..)"),
             NtVis(..) => f.pad("NtVis(..)"),
+            NtLifetime(..) => f.pad("NtLifetime(..)"),
         }
     }
 }