Remove a `Span` from `TokenKind::Interpolated`.

This span records the declaration of the metavariable in the LHS of the macro.
It's used in a couple of error messages. Unfortunately, it gets in the way of
the long-term goal of removing `TokenKind::Interpolated`. So this commit
removes it, which degrades a couple of (obscure) error messages but makes
things simpler and enables the next commit.

4 files changed, 7 insertions, 18 deletions

diff --git a/compiler/rustc_expand/src/mbe/diagnostics.rs b/compiler/rustc_expand/src/mbe/diagnostics.rs
index 464361cb402..3fee39dd085 100644
--- a/compiler/rustc_expand/src/mbe/diagnostics.rs
+++ b/compiler/rustc_expand/src/mbe/diagnostics.rs
@@ -73,12 +73,6 @@ pub(super) fn failed_to_match_macro<'cx>(
         && (matches!(expected_token.kind, TokenKind::Interpolated(_))
             || matches!(token.kind, TokenKind::Interpolated(_)))
     {
-        if let TokenKind::Interpolated(node) = &expected_token.kind {
-            err.span_label(node.1, "");
-        }
-        if let TokenKind::Interpolated(node) = &token.kind {
-            err.span_label(node.1, "");
-        }
         err.note("captured metavariables except for `:tt`, `:ident` and `:lifetime` cannot be compared to other tokens");
         err.note("see <https://doc.rust-lang.org/nightly/reference/macros-by-example.html#forwarding-a-matched-fragment> for more information");
 
diff --git a/compiler/rustc_expand/src/mbe/macro_parser.rs b/compiler/rustc_expand/src/mbe/macro_parser.rs
index ffb50f4c92e..27cf6fee702 100644
--- a/compiler/rustc_expand/src/mbe/macro_parser.rs
+++ b/compiler/rustc_expand/src/mbe/macro_parser.rs
@@ -75,10 +75,9 @@ pub(crate) use ParseResult::*;
 
 use crate::mbe::{macro_rules::Tracker, KleeneOp, TokenTree};
 
-use rustc_ast::token::{self, DocComment, Nonterminal, NonterminalKind, Token};
+use rustc_ast::token::{self, DocComment, NonterminalKind, Token};
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::sync::Lrc;
 use rustc_errors::ErrorGuaranteed;
 use rustc_lint_defs::pluralize;
 use rustc_parse::parser::{ParseNtResult, Parser};
@@ -392,7 +391,7 @@ pub(super) fn count_metavar_decls(matcher: &[TokenTree]) -> usize {
 #[derive(Debug, Clone)]
 pub(crate) enum NamedMatch {
     MatchedSeq(Vec<NamedMatch>),
-    MatchedSingle(ParseNtResult<Lrc<(Nonterminal, Span)>>),
+    MatchedSingle(ParseNtResult),
 }
 
 /// Performs a token equality check, ignoring syntax context (that is, an unhygienic comparison)
@@ -686,11 +685,7 @@ impl TtParser {
                             }
                             Ok(nt) => nt,
                         };
-                        mp.push_match(
-                            next_metavar,
-                            seq_depth,
-                            MatchedSingle(nt.map_nt(|nt| (Lrc::new((nt, span))))),
-                        );
+                        mp.push_match(next_metavar, seq_depth, MatchedSingle(nt));
                         mp.idx += 1;
                     } else {
                         unreachable!()
diff --git a/compiler/rustc_expand/src/proc_macro.rs b/compiler/rustc_expand/src/proc_macro.rs
index 4b5c148cb55..530059e53c2 100644
--- a/compiler/rustc_expand/src/proc_macro.rs
+++ b/compiler/rustc_expand/src/proc_macro.rs
@@ -127,7 +127,7 @@ impl MultiItemModifier for DeriveProcMacro {
                 Annotatable::Stmt(stmt) => token::NtStmt(stmt),
                 _ => unreachable!(),
             };
-            TokenStream::token_alone(token::Interpolated(Lrc::new((nt, span))), DUMMY_SP)
+            TokenStream::token_alone(token::Interpolated(Lrc::new(nt)), DUMMY_SP)
         } else {
             item.to_tokens()
         };
diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index 5a66b0fbdef..8cf96580161 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -259,7 +259,7 @@ impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStre
                     }));
                 }
 
-                Interpolated(ref nt) if let NtIdent(ident, is_raw) = &nt.0 => {
+                Interpolated(ref nt) if let NtIdent(ident, is_raw) = &**nt => {
                     trees.push(TokenTree::Ident(Ident {
                         sym: ident.name,
                         is_raw: matches!(is_raw, IdentIsRaw::Yes),
@@ -268,14 +268,14 @@ impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStre
                 }
 
                 Interpolated(nt) => {
-                    let stream = TokenStream::from_nonterminal_ast(&nt.0);
+                    let stream = TokenStream::from_nonterminal_ast(&nt);
                     // A hack used to pass AST fragments to attribute and derive
                     // macros as a single nonterminal token instead of a token
                     // stream. Such token needs to be "unwrapped" and not
                     // represented as a delimited group.
                     // FIXME: It needs to be removed, but there are some
                     // compatibility issues (see #73345).
-                    if crate::base::nt_pretty_printing_compatibility_hack(&nt.0, rustc.ecx.sess) {
+                    if crate::base::nt_pretty_printing_compatibility_hack(&nt, rustc.ecx.sess) {
                         trees.extend(Self::from_internal((stream, rustc)));
                     } else {
                         trees.push(TokenTree::Group(Group {