Auto merge of #39419 - jseyfried:simplify_tokentree, r=nrc

Simplify `TokenTree` and fix `macro_rules!` bugs

This PR
 - fixes #39390, fixes #39403, and fixes #39404 (each is a [breaking-change], see issues for examples),
 - fixes #39889,
 - simplifies and optimizes macro invocation parsing,
 - cleans up `ext::tt::transcribe`,
 - removes `tokenstream::TokenTree::Sequence` and `Token::MatchNt`,
   - instead, adds a new type `ext::tt::quoted::TokenTree` for use by `macro_rules!` (`ext::tt`)
 - removes `parser.quote_depth` and `parser.parsing_token_tree`, and
 - removes `quote_matcher!`.
   - Instead, use `quote_tokens!` and `ext::tt::quoted::parse` the result with `expect_matchers=true`.
   - I found no outside uses of `quote_matcher!` when searching Rust code on Github.

r? @nrc

1 files changed, 2 insertions, 5 deletions

diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index 0f0c6d0ca83..5b65aac92b8 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -50,8 +50,8 @@ pub enum DelimToken {
 }
 
 impl DelimToken {
-    pub fn len(&self) -> u32 {
-        if *self == NoDelim { 0 } else { 1 }
+    pub fn len(self) -> usize {
+        if self == NoDelim { 0 } else { 1 }
     }
 }
 
@@ -152,9 +152,6 @@ pub enum Token {
     // Can be expanded into several tokens.
     /// Doc comment
     DocComment(ast::Name),
-    // In left-hand-sides of MBE macros:
-    /// Parse a nonterminal (name to bind, name of NT)
-    MatchNt(ast::Ident, ast::Ident),
     // In right-hand-sides of MBE macros:
     /// A syntactic variable that will be filled in by macro expansion.
     SubstNt(ast::Ident),