Rollup merge of #142657 - tgross35:nonoptional-fragment-specifiers-cleanup, r=petrochenkov

mbe: Clean up code with non-optional `NonterminalKind`

Since [rust-lang/rust#128425], the fragment specifier is unconditionally required in all
editions. This means `NonTerminalKind` no longer needs to be optional,
as we can reject this code during the expansion of `macro_rules!` rather
than handling it throughout the code. Do this cleanup here.

[rust-lang/rust#128425]: https://github.com/rust-lang/rust/pull/128425

17 files changed, 216 insertions, 164 deletions

diff --git a/compiler/rustc_ast/src/token.rs b/compiler/rustc_ast/src/token.rs
index 54781e8235e..9b4535dcfbc 100644
--- a/compiler/rustc_ast/src/token.rs
+++ b/compiler/rustc_ast/src/token.rs
@@ -1085,6 +1085,7 @@ pub enum NtExprKind {
     Expr2021 { inferred: bool },
 }
 
+/// A macro nonterminal, known in documentation as a fragment specifier.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Encodable, Decodable, Hash, HashStable_Generic)]
 pub enum NonterminalKind {
     Item,
diff --git a/compiler/rustc_expand/src/errors.rs b/compiler/rustc_expand/src/errors.rs
index 714ba3bf0f4..4167be93e7b 100644
--- a/compiler/rustc_expand/src/errors.rs
+++ b/compiler/rustc_expand/src/errors.rs
@@ -444,7 +444,7 @@ pub(crate) struct InvalidFragmentSpecifier {
     #[primary_span]
     pub span: Span,
     pub fragment: Ident,
-    pub help: String,
+    pub help: &'static str,
 }
 
 #[derive(Diagnostic)]
diff --git a/compiler/rustc_expand/src/mbe.rs b/compiler/rustc_expand/src/mbe.rs
index 4ff8c02bcdb..3082c881a7a 100644
--- a/compiler/rustc_expand/src/mbe.rs
+++ b/compiler/rustc_expand/src/mbe.rs
@@ -78,7 +78,13 @@ enum TokenTree {
     /// only covers the ident, e.g. `var`.)
     MetaVar(Span, Ident),
     /// e.g., `$var:expr`. Only appears on the LHS.
-    MetaVarDecl(Span, Ident /* name to bind */, Option<NonterminalKind>),
+    MetaVarDecl {
+        span: Span,
+        /// Name to bind.
+        name: Ident,
+        /// The fragment specifier.
+        kind: NonterminalKind,
+    },
     /// A meta-variable expression inside `${...}`.
     MetaVarExpr(DelimSpan, MetaVarExpr),
 }
@@ -102,7 +108,7 @@ impl TokenTree {
         match *self {
             TokenTree::Token(Token { span, .. })
             | TokenTree::MetaVar(span, _)
-            | TokenTree::MetaVarDecl(span, _, _) => span,
+            | TokenTree::MetaVarDecl { span, .. } => span,
             TokenTree::Delimited(span, ..)
             | TokenTree::MetaVarExpr(span, _)
             | TokenTree::Sequence(span, _) => span.entire(),
diff --git a/compiler/rustc_expand/src/mbe/diagnostics.rs b/compiler/rustc_expand/src/mbe/diagnostics.rs
index 698492f42e2..99aa376626d 100644
--- a/compiler/rustc_expand/src/mbe/diagnostics.rs
+++ b/compiler/rustc_expand/src/mbe/diagnostics.rs
@@ -24,6 +24,7 @@ pub(super) fn failed_to_match_macro(
     arg: TokenStream,
     lhses: &[Vec<MatcherLoc>],
 ) -> (Span, ErrorGuaranteed) {
+    debug!("failed to match macro");
     // An error occurred, try the expansion again, tracking the expansion closely for better
     // diagnostics.
     let mut tracker = CollectTrackerAndEmitter::new(psess.dcx(), sp);
diff --git a/compiler/rustc_expand/src/mbe/macro_check.rs b/compiler/rustc_expand/src/mbe/macro_check.rs
index 3cd803c3e84..dc2d46c4a14 100644
--- a/compiler/rustc_expand/src/mbe/macro_check.rs
+++ b/compiler/rustc_expand/src/mbe/macro_check.rs
@@ -117,7 +117,6 @@ use rustc_session::parse::ParseSess;
 use rustc_span::{ErrorGuaranteed, MacroRulesNormalizedIdent, Span, kw};
 use smallvec::SmallVec;
 
-use super::quoted::VALID_FRAGMENT_NAMES_MSG;
 use crate::errors;
 use crate::mbe::{KleeneToken, TokenTree};
 
@@ -263,14 +262,7 @@ fn check_binders(
             }
         }
         // Similarly, this can only happen when checking a toplevel macro.
-        TokenTree::MetaVarDecl(span, name, kind) => {
-            if kind.is_none() && node_id != DUMMY_NODE_ID {
-                psess.dcx().emit_err(errors::MissingFragmentSpecifier {
-                    span,
-                    add_span: span.shrink_to_hi(),
-                    valid: VALID_FRAGMENT_NAMES_MSG,
-                });
-            }
+        TokenTree::MetaVarDecl { span, name, .. } => {
             if !macros.is_empty() {
                 psess.dcx().span_bug(span, "unexpected MetaVarDecl in nested lhs");
             }
@@ -339,7 +331,7 @@ fn check_occurrences(
 ) {
     match *rhs {
         TokenTree::Token(..) => {}
-        TokenTree::MetaVarDecl(span, _name, _kind) => {
+        TokenTree::MetaVarDecl { span, .. } => {
             psess.dcx().span_bug(span, "unexpected MetaVarDecl in rhs")
         }
         TokenTree::MetaVar(span, name) => {
diff --git a/compiler/rustc_expand/src/mbe/macro_parser.rs b/compiler/rustc_expand/src/mbe/macro_parser.rs
index c78beb40688..802e43209a5 100644
--- a/compiler/rustc_expand/src/mbe/macro_parser.rs
+++ b/compiler/rustc_expand/src/mbe/macro_parser.rs
@@ -122,7 +122,7 @@ pub(crate) enum MatcherLoc {
     MetaVarDecl {
         span: Span,
         bind: Ident,
-        kind: Option<NonterminalKind>,
+        kind: NonterminalKind,
         next_metavar: usize,
         seq_depth: usize,
     },
@@ -151,12 +151,7 @@ impl Display for MatcherLoc {
                 write!(f, "{}", token_descr(token))
             }
             MatcherLoc::MetaVarDecl { bind, kind, .. } => {
-                write!(f, "meta-variable `${bind}")?;
-                if let Some(kind) = kind {
-                    write!(f, ":{kind}")?;
-                }
-                write!(f, "`")?;
-                Ok(())
+                write!(f, "meta-variable `${bind}:{kind}`")
             }
             MatcherLoc::Eof => f.write_str("end of macro"),
 
@@ -220,7 +215,7 @@ pub(super) fn compute_locs(matcher: &[TokenTree]) -> Vec<MatcherLoc> {
                         seq_depth,
                     };
                 }
-                &TokenTree::MetaVarDecl(span, bind, kind) => {
+                &TokenTree::MetaVarDecl { span, name: bind, kind } => {
                     locs.push(MatcherLoc::MetaVarDecl {
                         span,
                         bind,
@@ -330,7 +325,7 @@ pub(super) fn count_metavar_decls(matcher: &[TokenTree]) -> usize {
     matcher
         .iter()
         .map(|tt| match tt {
-            TokenTree::MetaVarDecl(..) => 1,
+            TokenTree::MetaVarDecl { .. } => 1,
             TokenTree::Sequence(_, seq) => seq.num_captures,
             TokenTree::Delimited(.., delim) => count_metavar_decls(&delim.tts),
             TokenTree::Token(..) => 0,
@@ -551,18 +546,12 @@ impl TtParser {
                     mp.idx = idx_first;
                     self.cur_mps.push(mp);
                 }
-                &MatcherLoc::MetaVarDecl { span, kind, .. } => {
+                &MatcherLoc::MetaVarDecl { kind, .. } => {
                     // Built-in nonterminals never start with these tokens, so we can eliminate
                     // them from consideration. We use the span of the metavariable declaration
                     // to determine any edition-specific matching behavior for non-terminals.
-                    if let Some(kind) = kind {
-                        if Parser::nonterminal_may_begin_with(kind, token) {
-                            self.bb_mps.push(mp);
-                        }
-                    } else {
-                        // E.g. `$e` instead of `$e:expr`, reported as a hard error if actually used.
-                        // Both this check and the one in `nameize` are necessary, surprisingly.
-                        return Some(Error(span, "missing fragment specifier".to_string()));
+                    if Parser::nonterminal_may_begin_with(kind, token) {
+                        self.bb_mps.push(mp);
                     }
                 }
                 MatcherLoc::Eof => {
@@ -666,11 +655,7 @@ impl TtParser {
                     let mut mp = self.bb_mps.pop().unwrap();
                     let loc = &matcher[mp.idx];
                     if let &MatcherLoc::MetaVarDecl {
-                        span,
-                        kind: Some(kind),
-                        next_metavar,
-                        seq_depth,
-                        ..
+                        span, kind, next_metavar, seq_depth, ..
                     } = loc
                     {
                         // We use the span of the metavariable declaration to determine any
@@ -715,7 +700,7 @@ impl TtParser {
             .bb_mps
             .iter()
             .map(|mp| match &matcher[mp.idx] {
-                MatcherLoc::MetaVarDecl { bind, kind: Some(kind), .. } => {
+                MatcherLoc::MetaVarDecl { bind, kind, .. } => {
                     format!("{kind} ('{bind}')")
                 }
                 _ => unreachable!(),
@@ -745,19 +730,13 @@ impl TtParser {
         // `NamedParseResult`. Otherwise, it's an error.
         let mut ret_val = FxHashMap::default();
         for loc in matcher {
-            if let &MatcherLoc::MetaVarDecl { span, bind, kind, .. } = loc {
-                if kind.is_some() {
-                    match ret_val.entry(MacroRulesNormalizedIdent::new(bind)) {
-                        Vacant(spot) => spot.insert(res.next().unwrap()),
-                        Occupied(..) => {
-                            return Error(span, format!("duplicated bind name: {bind}"));
-                        }
-                    };
-                } else {
-                    // E.g. `$e` instead of `$e:expr`, reported as a hard error if actually used.
-                    // Both this check and the one in `parse_tt_inner` are necessary, surprisingly.
-                    return Error(span, "missing fragment specifier".to_string());
-                }
+            if let &MatcherLoc::MetaVarDecl { span, bind, .. } = loc {
+                match ret_val.entry(MacroRulesNormalizedIdent::new(bind)) {
+                    Vacant(spot) => spot.insert(res.next().unwrap()),
+                    Occupied(..) => {
+                        return Error(span, format!("duplicated bind name: {bind}"));
+                    }
+                };
             }
         }
         Success(ret_val)
diff --git a/compiler/rustc_expand/src/mbe/macro_rules.rs b/compiler/rustc_expand/src/mbe/macro_rules.rs
index 783f061ec6c..432ab324740 100644
--- a/compiler/rustc_expand/src/mbe/macro_rules.rs
+++ b/compiler/rustc_expand/src/mbe/macro_rules.rs
@@ -392,7 +392,7 @@ pub fn compile_declarative_macro(
 
     let lhs_nm = Ident::new(sym::lhs, span);
     let rhs_nm = Ident::new(sym::rhs, span);
-    let tt_spec = Some(NonterminalKind::TT);
+    let tt_spec = NonterminalKind::TT;
     let macro_rules = macro_def.macro_rules;
 
     // Parse the macro_rules! invocation
@@ -407,9 +407,9 @@ pub fn compile_declarative_macro(
             DelimSpan::dummy(),
             mbe::SequenceRepetition {
                 tts: vec![
-                    mbe::TokenTree::MetaVarDecl(span, lhs_nm, tt_spec),
+                    mbe::TokenTree::MetaVarDecl { span, name: lhs_nm, kind: tt_spec },
                     mbe::TokenTree::token(token::FatArrow, span),
-                    mbe::TokenTree::MetaVarDecl(span, rhs_nm, tt_spec),
+                    mbe::TokenTree::MetaVarDecl { span, name: rhs_nm, kind: tt_spec },
                 ],
                 separator: Some(Token::new(
                     if macro_rules { token::Semi } else { token::Comma },
@@ -448,6 +448,7 @@ pub fn compile_declarative_macro(
         match tt_parser.parse_tt(&mut Cow::Owned(parser), &argument_gram, &mut NoopTracker) {
             Success(m) => m,
             Failure(()) => {
+                debug!("failed to parse macro tt");
                 // The fast `NoopTracker` doesn't have any info on failure, so we need to retry it
                 // with another one that gives us the information we need.
                 // For this we need to reclone the macro body as the previous parser consumed it.
@@ -616,7 +617,7 @@ fn is_empty_token_tree(sess: &Session, seq: &mbe::SequenceRepetition) -> bool {
         let mut iter = seq.tts.iter().peekable();
         while let Some(tt) = iter.next() {
             match tt {
-                mbe::TokenTree::MetaVarDecl(_, _, Some(NonterminalKind::Vis)) => {}
+                mbe::TokenTree::MetaVarDecl { kind: NonterminalKind::Vis, .. } => {}
                 mbe::TokenTree::Token(t @ Token { kind: DocComment(..), .. }) => {
                     let mut now = t;
                     while let Some(&mbe::TokenTree::Token(
@@ -651,7 +652,7 @@ fn check_redundant_vis_repetition(
 ) {
     let is_zero_or_one: bool = seq.kleene.op == KleeneOp::ZeroOrOne;
     let is_vis = seq.tts.first().map_or(false, |tt| {
-        matches!(tt, mbe::TokenTree::MetaVarDecl(_, _, Some(NonterminalKind::Vis)))
+        matches!(tt, mbe::TokenTree::MetaVarDecl { kind: NonterminalKind::Vis, .. })
     });
 
     if is_vis && is_zero_or_one {
@@ -678,7 +679,7 @@ fn check_lhs_no_empty_seq(sess: &Session, tts: &[mbe::TokenTree]) -> Result<(),
         match tt {
             TokenTree::Token(..)
             | TokenTree::MetaVar(..)
-            | TokenTree::MetaVarDecl(..)
+            | TokenTree::MetaVarDecl { .. }
             | TokenTree::MetaVarExpr(..) => (),
             TokenTree::Delimited(.., del) => check_lhs_no_empty_seq(sess, &del.tts)?,
             TokenTree::Sequence(span, seq) => {
@@ -777,7 +778,7 @@ impl<'tt> FirstSets<'tt> {
                 match tt {
                     TokenTree::Token(..)
                     | TokenTree::MetaVar(..)
-                    | TokenTree::MetaVarDecl(..)
+                    | TokenTree::MetaVarDecl { .. }
                     | TokenTree::MetaVarExpr(..) => {
                         first.replace_with(TtHandle::TtRef(tt));
                     }
@@ -845,7 +846,7 @@ impl<'tt> FirstSets<'tt> {
             match tt {
                 TokenTree::Token(..)
                 | TokenTree::MetaVar(..)
-                | TokenTree::MetaVarDecl(..)
+                | TokenTree::MetaVarDecl { .. }
                 | TokenTree::MetaVarExpr(..) => {
                     first.add_one(TtHandle::TtRef(tt));
                     return first;
@@ -1084,7 +1085,7 @@ fn check_matcher_core<'tt>(
         match token {
             TokenTree::Token(..)
             | TokenTree::MetaVar(..)
-            | TokenTree::MetaVarDecl(..)
+            | TokenTree::MetaVarDecl { .. }
             | TokenTree::MetaVarExpr(..) => {
                 if token_can_be_followed_by_any(token) {
                     // don't need to track tokens that work with any,
@@ -1152,7 +1153,7 @@ fn check_matcher_core<'tt>(
         // Now `last` holds the complete set of NT tokens that could
         // end the sequence before SUFFIX. Check that every one works with `suffix`.
         for tt in &last.tokens {
-            if let &TokenTree::MetaVarDecl(span, name, Some(kind)) = tt.get() {
+            if let &TokenTree::MetaVarDecl { span, name, kind } = tt.get() {
                 for next_token in &suffix_first.tokens {
                     let next_token = next_token.get();
 
@@ -1172,11 +1173,11 @@ fn check_matcher_core<'tt>(
                         )
                     {
                         // It is suggestion to use pat_param, for example: $x:pat -> $x:pat_param.
-                        let suggestion = quoted_tt_to_string(&TokenTree::MetaVarDecl(
+                        let suggestion = quoted_tt_to_string(&TokenTree::MetaVarDecl {
                             span,
                             name,
-                            Some(NonterminalKind::Pat(PatParam { inferred: false })),
-                        ));
+                            kind: NonterminalKind::Pat(PatParam { inferred: false }),
+                        });
                         sess.psess.buffer_lint(
                             RUST_2021_INCOMPATIBLE_OR_PATTERNS,
                             span,
@@ -1212,11 +1213,11 @@ fn check_matcher_core<'tt>(
                                 && sess.psess.edition.at_least_rust_2021()
                                 && next_token.is_token(&token::Or)
                             {
-                                let suggestion = quoted_tt_to_string(&TokenTree::MetaVarDecl(
+                                let suggestion = quoted_tt_to_string(&TokenTree::MetaVarDecl {
                                     span,
                                     name,
-                                    Some(NonterminalKind::Pat(PatParam { inferred: false })),
-                                ));
+                                    kind: NonterminalKind::Pat(PatParam { inferred: false }),
+                                });
                                 err.span_suggestion(
                                     span,
                                     "try a `pat_param` fragment specifier instead",
@@ -1254,7 +1255,7 @@ fn check_matcher_core<'tt>(
 }
 
 fn token_can_be_followed_by_any(tok: &mbe::TokenTree) -> bool {
-    if let mbe::TokenTree::MetaVarDecl(_, _, Some(kind)) = *tok {
+    if let mbe::TokenTree::MetaVarDecl { kind, .. } = *tok {
         frag_can_be_followed_by_any(kind)
     } else {
         // (Non NT's can always be followed by anything in matchers.)
@@ -1367,7 +1368,7 @@ fn is_in_follow(tok: &mbe::TokenTree, kind: NonterminalKind) -> IsInFollow {
                         }
                         _ => IsInFollow::No(TOKENS),
                     },
-                    TokenTree::MetaVarDecl(_, _, Some(NonterminalKind::Block)) => IsInFollow::Yes,
+                    TokenTree::MetaVarDecl { kind: NonterminalKind::Block, .. } => IsInFollow::Yes,
                     _ => IsInFollow::No(TOKENS),
                 }
             }
@@ -1400,11 +1401,10 @@ fn is_in_follow(tok: &mbe::TokenTree, kind: NonterminalKind) -> IsInFollow {
                             }
                         }
                     },
-                    TokenTree::MetaVarDecl(
-                        _,
-                        _,
-                        Some(NonterminalKind::Ident | NonterminalKind::Ty | NonterminalKind::Path),
-                    ) => IsInFollow::Yes,
+                    TokenTree::MetaVarDecl {
+                        kind: NonterminalKind::Ident | NonterminalKind::Ty | NonterminalKind::Path,
+                        ..
+                    } => IsInFollow::Yes,
                     _ => IsInFollow::No(TOKENS),
                 }
             }
@@ -1416,8 +1416,7 @@ fn quoted_tt_to_string(tt: &mbe::TokenTree) -> String {
     match tt {
         mbe::TokenTree::Token(token) => pprust::token_to_string(token).into(),
         mbe::TokenTree::MetaVar(_, name) => format!("${name}"),
-        mbe::TokenTree::MetaVarDecl(_, name, Some(kind)) => format!("${name}:{kind}"),
-        mbe::TokenTree::MetaVarDecl(_, name, None) => format!("${name}:"),
+        mbe::TokenTree::MetaVarDecl { name, kind, .. } => format!("${name}:{kind}"),
         _ => panic!(
             "{}",
             "unexpected mbe::TokenTree::{Sequence or Delimited} \
diff --git a/compiler/rustc_expand/src/mbe/quoted.rs b/compiler/rustc_expand/src/mbe/quoted.rs
index 0c2362f23bc..2daa4e71558 100644
--- a/compiler/rustc_expand/src/mbe/quoted.rs
+++ b/compiler/rustc_expand/src/mbe/quoted.rs
@@ -54,66 +54,78 @@ pub(super) fn parse(
         // Given the parsed tree, if there is a metavar and we are expecting matchers, actually
         // parse out the matcher (i.e., in `$id:ident` this would parse the `:` and `ident`).
         let tree = parse_tree(tree, &mut iter, parsing_patterns, sess, node_id, features, edition);
-        match tree {
-            TokenTree::MetaVar(start_sp, ident) if parsing_patterns => {
-                // Not consuming the next token immediately, as it may not be a colon
-                let span = match iter.peek() {
-                    Some(&tokenstream::TokenTree::Token(
-                        Token { kind: token::Colon, span: colon_span },
-                        _,
-                    )) => {
-                        // Consume the colon first
-                        iter.next();
-
-                        // It's ok to consume the next tree no matter how,
-                        // since if it's not a token then it will be an invalid declaration.
-                        match iter.next() {
-                            Some(tokenstream::TokenTree::Token(token, _)) => match token.ident() {
-                                Some((fragment, _)) => {
-                                    let span = token.span.with_lo(start_sp.lo());
-                                    let edition = || {
-                                        // FIXME(#85708) - once we properly decode a foreign
-                                        // crate's `SyntaxContext::root`, then we can replace
-                                        // this with just `span.edition()`. A
-                                        // `SyntaxContext::root()` from the current crate will
-                                        // have the edition of the current crate, and a
-                                        // `SyntaxContext::root()` from a foreign crate will
-                                        // have the edition of that crate (which we manually
-                                        // retrieve via the `edition` parameter).
-                                        if !span.from_expansion() {
-                                            edition
-                                        } else {
-                                            span.edition()
-                                        }
-                                    };
-                                    let kind = NonterminalKind::from_symbol(fragment.name, edition)
-                                        .unwrap_or_else(|| {
-                                            sess.dcx().emit_err(errors::InvalidFragmentSpecifier {
-                                                span,
-                                                fragment,
-                                                help: VALID_FRAGMENT_NAMES_MSG.into(),
-                                            });
-                                            NonterminalKind::Ident
-                                        });
-                                    result.push(TokenTree::MetaVarDecl(span, ident, Some(kind)));
-                                    continue;
-                                }
-                                _ => token.span,
-                            },
-                            // Invalid, return a nice source location
-                            _ => colon_span.with_lo(start_sp.lo()),
-                        }
-                    }
-                    // Whether it's none or some other tree, it doesn't belong to
-                    // the current meta variable, returning the original span.
-                    _ => start_sp,
-                };
 
-                result.push(TokenTree::MetaVarDecl(span, ident, None));
-            }
+        if !parsing_patterns {
+            // No matchers allowed, nothing to process here
+            result.push(tree);
+            continue;
+        }
+
+        let TokenTree::MetaVar(start_sp, ident) = tree else {
+            // Not a metavariable, just return the tree
+            result.push(tree);
+            continue;
+        };
 
-            // Not a metavar or no matchers allowed, so just return the tree
-            _ => result.push(tree),
+        // Push a metavariable with no fragment specifier at the given span
+        let mut missing_fragment_specifier = |span| {
+            sess.dcx().emit_err(errors::MissingFragmentSpecifier {
+                span,
+                add_span: span.shrink_to_hi(),
+                valid: VALID_FRAGMENT_NAMES_MSG,
+            });
+
+            // Fall back to a `TokenTree` since that will match anything if we continue expanding.
+            result.push(TokenTree::MetaVarDecl { span, name: ident, kind: NonterminalKind::TT });
+        };
+
+        // Not consuming the next token immediately, as it may not be a colon
+        if let Some(peek) = iter.peek()
+            && let tokenstream::TokenTree::Token(token, _spacing) = peek
+            && let Token { kind: token::Colon, span: colon_span } = token
+        {
+            // Next token is a colon; consume it
+            iter.next();
+
+            // It's ok to consume the next tree no matter how,
+            // since if it's not a token then it will be an invalid declaration.
+            let Some(tokenstream::TokenTree::Token(token, _)) = iter.next() else {
+                // Invalid, return a nice source location as `var:`
+                missing_fragment_specifier(colon_span.with_lo(start_sp.lo()));
+                continue;
+            };
+
+            let Some((fragment, _)) = token.ident() else {
+                // No identifier for the fragment specifier;
+                missing_fragment_specifier(token.span);
+                continue;
+            };
+
+            let span = token.span.with_lo(start_sp.lo());
+            let edition = || {
+                // FIXME(#85708) - once we properly decode a foreign
+                // crate's `SyntaxContext::root`, then we can replace
+                // this with just `span.edition()`. A
+                // `SyntaxContext::root()` from the current crate will
+                // have the edition of the current crate, and a
+                // `SyntaxContext::root()` from a foreign crate will
+                // have the edition of that crate (which we manually
+                // retrieve via the `edition` parameter).
+                if !span.from_expansion() { edition } else { span.edition() }
+            };
+            let kind = NonterminalKind::from_symbol(fragment.name, edition).unwrap_or_else(|| {
+                sess.dcx().emit_err(errors::InvalidFragmentSpecifier {
+                    span,
+                    fragment,
+                    help: VALID_FRAGMENT_NAMES_MSG,
+                });
+                NonterminalKind::TT
+            });
+            result.push(TokenTree::MetaVarDecl { span, name: ident, kind });
+        } else {
+            // Whether it's none or some other tree, it doesn't belong to
+            // the current meta variable, returning the original span.
+            missing_fragment_specifier(start_sp);
         }
     }
     result
diff --git a/compiler/rustc_expand/src/mbe/transcribe.rs b/compiler/rustc_expand/src/mbe/transcribe.rs
index 0520be5fbae..a8c4a9e4b1b 100644
--- a/compiler/rustc_expand/src/mbe/transcribe.rs
+++ b/compiler/rustc_expand/src/mbe/transcribe.rs
@@ -283,7 +283,7 @@ pub(super) fn transcribe<'a>(
             }
 
             // There should be no meta-var declarations in the invocation of a macro.
-            mbe::TokenTree::MetaVarDecl(..) => panic!("unexpected `TokenTree::MetaVarDecl`"),
+            mbe::TokenTree::MetaVarDecl { .. } => panic!("unexpected `TokenTree::MetaVarDecl`"),
         }
     }
 }
@@ -776,7 +776,7 @@ fn lockstep_iter_size(
                 size.with(lockstep_iter_size(tt, interpolations, repeats))
             })
         }
-        TokenTree::MetaVar(_, name) | TokenTree::MetaVarDecl(_, name, _) => {
+        TokenTree::MetaVar(_, name) | TokenTree::MetaVarDecl { name, .. } => {
             let name = MacroRulesNormalizedIdent::new(*name);
             match lookup_cur_matched(name, interpolations, repeats) {
                 Some(matched) => match matched {
diff --git a/tests/ui/macros/macro-match-nonterminal.rs b/tests/ui/macros/macro-match-nonterminal.rs
index fa2af945a1f..1643cddb192 100644
--- a/tests/ui/macros/macro-match-nonterminal.rs
+++ b/tests/ui/macros/macro-match-nonterminal.rs
@@ -2,11 +2,10 @@ macro_rules! test {
     ($a, $b) => {
         //~^ ERROR missing fragment
         //~| ERROR missing fragment
-        //~| ERROR missing fragment
         ()
     };
 }
 
 fn main() {
-    test!()
+    test!() //~ ERROR unexpected end of macro invocation
 }
diff --git a/tests/ui/macros/macro-match-nonterminal.stderr b/tests/ui/macros/macro-match-nonterminal.stderr
index 8196d795c4c..a92d099ca00 100644
--- a/tests/ui/macros/macro-match-nonterminal.stderr
+++ b/tests/ui/macros/macro-match-nonterminal.stderr
@@ -24,7 +24,16 @@ help: try adding a specifier here
 LL |     ($a, $b:spec) => {
    |            +++++
 
-error: missing fragment specifier
+error: unexpected end of macro invocation
+  --> $DIR/macro-match-nonterminal.rs:10:5
+   |
+LL | macro_rules! test {
+   | ----------------- when calling this macro
+...
+LL |     test!()
+   |     ^^^^^^^ missing tokens in macro arguments
+   |
+note: while trying to match meta-variable `$a:tt`
   --> $DIR/macro-match-nonterminal.rs:2:6
    |
 LL |     ($a, $b) => {
diff --git a/tests/ui/macros/macro-missing-fragment-deduplication.rs b/tests/ui/macros/macro-missing-fragment-deduplication.rs
index 481f08fa111..fc81c713b4d 100644
--- a/tests/ui/macros/macro-missing-fragment-deduplication.rs
+++ b/tests/ui/macros/macro-missing-fragment-deduplication.rs
@@ -2,12 +2,11 @@
 
 macro_rules! m {
     ($name) => {}; //~ ERROR missing fragment
-                   //~| ERROR missing fragment
 }
 
 fn main() {
-    m!();
-    m!();
-    m!();
-    m!();
+    m!(); //~ ERROR unexpected end
+    m!(); //~ ERROR unexpected end
+    m!(); //~ ERROR unexpected end
+    m!(); //~ ERROR unexpected end
 }
diff --git a/tests/ui/macros/macro-missing-fragment-deduplication.stderr b/tests/ui/macros/macro-missing-fragment-deduplication.stderr
index 820f7eb3cf7..29d2ae0e16e 100644
--- a/tests/ui/macros/macro-missing-fragment-deduplication.stderr
+++ b/tests/ui/macros/macro-missing-fragment-deduplication.stderr
@@ -11,11 +11,65 @@ help: try adding a specifier here
 LL |     ($name:spec) => {};
    |           +++++
 
-error: missing fragment specifier
+error: unexpected end of macro invocation
+  --> $DIR/macro-missing-fragment-deduplication.rs:8:5
+   |
+LL | macro_rules! m {
+   | -------------- when calling this macro
+...
+LL |     m!();
+   |     ^^^^ missing tokens in macro arguments
+   |
+note: while trying to match meta-variable `$name:tt`
+  --> $DIR/macro-missing-fragment-deduplication.rs:4:6
+   |
+LL |     ($name) => {};
+   |      ^^^^^
+
+error: unexpected end of macro invocation
+  --> $DIR/macro-missing-fragment-deduplication.rs:9:5
+   |
+LL | macro_rules! m {
+   | -------------- when calling this macro
+...
+LL |     m!();
+   |     ^^^^ missing tokens in macro arguments
+   |
+note: while trying to match meta-variable `$name:tt`
+  --> $DIR/macro-missing-fragment-deduplication.rs:4:6
+   |
+LL |     ($name) => {};
+   |      ^^^^^
+
+error: unexpected end of macro invocation
+  --> $DIR/macro-missing-fragment-deduplication.rs:10:5
+   |
+LL | macro_rules! m {
+   | -------------- when calling this macro
+...
+LL |     m!();
+   |     ^^^^ missing tokens in macro arguments
+   |
+note: while trying to match meta-variable `$name:tt`
+  --> $DIR/macro-missing-fragment-deduplication.rs:4:6
+   |
+LL |     ($name) => {};
+   |      ^^^^^
+
+error: unexpected end of macro invocation
+  --> $DIR/macro-missing-fragment-deduplication.rs:11:5
+   |
+LL | macro_rules! m {
+   | -------------- when calling this macro
+...
+LL |     m!();
+   |     ^^^^ missing tokens in macro arguments
+   |
+note: while trying to match meta-variable `$name:tt`
   --> $DIR/macro-missing-fragment-deduplication.rs:4:6
    |
 LL |     ($name) => {};
    |      ^^^^^
 
-error: aborting due to 2 previous errors
+error: aborting due to 5 previous errors
 
diff --git a/tests/ui/macros/macro-missing-fragment.rs b/tests/ui/macros/macro-missing-fragment.rs
index 533aa147bcb..7ed9074020e 100644
--- a/tests/ui/macros/macro-missing-fragment.rs
+++ b/tests/ui/macros/macro-missing-fragment.rs
@@ -2,7 +2,6 @@
 
 macro_rules! used_arm {
     ( $( any_token $field_rust_type )* ) => {}; //~ ERROR missing fragment
-                                                //~| ERROR missing fragment
 }
 
 macro_rules! used_macro_unused_arm {
diff --git a/tests/ui/macros/macro-missing-fragment.stderr b/tests/ui/macros/macro-missing-fragment.stderr
index 4a99d7d949c..886292378d1 100644
--- a/tests/ui/macros/macro-missing-fragment.stderr
+++ b/tests/ui/macros/macro-missing-fragment.stderr
@@ -12,7 +12,7 @@ LL |     ( $( any_token $field_rust_type:spec )* ) => {};
    |                                    +++++
 
 error: missing fragment specifier
-  --> $DIR/macro-missing-fragment.rs:10:7
+  --> $DIR/macro-missing-fragment.rs:9:7
    |
 LL |     ( $name ) => {};
    |       ^^^^^
@@ -25,7 +25,7 @@ LL |     ( $name:spec ) => {};
    |            +++++
 
 error: missing fragment specifier
-  --> $DIR/macro-missing-fragment.rs:14:7
+  --> $DIR/macro-missing-fragment.rs:13:7
    |
 LL |     ( $name ) => {};
    |       ^^^^^
@@ -37,11 +37,5 @@ help: try adding a specifier here
 LL |     ( $name:spec ) => {};
    |            +++++
 
-error: missing fragment specifier
-  --> $DIR/macro-missing-fragment.rs:4:20
-   |
-LL |     ( $( any_token $field_rust_type )* ) => {};
-   |                    ^^^^^^^^^^^^^^^^
-
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors
 
diff --git a/tests/ui/parser/macro/issue-33569.rs b/tests/ui/parser/macro/issue-33569.rs
index e0a5352ab06..7288fa858db 100644
--- a/tests/ui/parser/macro/issue-33569.rs
+++ b/tests/ui/parser/macro/issue-33569.rs
@@ -1,11 +1,10 @@
 macro_rules! foo {
     { $+ } => { //~ ERROR expected identifier, found `+`
                 //~^ ERROR missing fragment specifier
-                //~| ERROR missing fragment specifier
         $(x)(y) //~ ERROR expected one of: `*`, `+`, or `?`
     }
 }
 
-foo!();
+foo!(); //~ ERROR unexpected end
 
 fn main() {}
diff --git a/tests/ui/parser/macro/issue-33569.stderr b/tests/ui/parser/macro/issue-33569.stderr
index 0d53c04c1c9..dd8e38f0d6e 100644
--- a/tests/ui/parser/macro/issue-33569.stderr
+++ b/tests/ui/parser/macro/issue-33569.stderr
@@ -4,12 +4,6 @@ error: expected identifier, found `+`
 LL |     { $+ } => {
    |        ^
 
-error: expected one of: `*`, `+`, or `?`
-  --> $DIR/issue-33569.rs:5:13
-   |
-LL |         $(x)(y)
-   |             ^^^
-
 error: missing fragment specifier
   --> $DIR/issue-33569.rs:2:8
    |
@@ -23,7 +17,22 @@ help: try adding a specifier here
 LL |     { $+:spec } => {
    |         +++++
 
-error: missing fragment specifier
+error: expected one of: `*`, `+`, or `?`
+  --> $DIR/issue-33569.rs:4:13
+   |
+LL |         $(x)(y)
+   |             ^^^
+
+error: unexpected end of macro invocation
+  --> $DIR/issue-33569.rs:8:1
+   |
+LL | macro_rules! foo {
+   | ---------------- when calling this macro
+...
+LL | foo!();
+   | ^^^^^^ missing tokens in macro arguments
+   |
+note: while trying to match meta-variable `$<!dummy!>:tt`
   --> $DIR/issue-33569.rs:2:8
    |
 LL |     { $+ } => {