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Diffstat (limited to 'crates/mbe/src/expander/matcher.rs')
| -rw-r--r-- | crates/mbe/src/expander/matcher.rs | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/crates/mbe/src/expander/matcher.rs b/crates/mbe/src/expander/matcher.rs index 3f656df25f..b6c5c1026e 100644 --- a/crates/mbe/src/expander/matcher.rs +++ b/crates/mbe/src/expander/matcher.rs @@ -698,12 +698,16 @@ fn match_meta_var(kind: MetaVarKind, input: &mut TtIter<'_>) -> ExpandResult<Opt MetaVarKind::Item => parser::PrefixEntryPoint::Item, MetaVarKind::Vis => parser::PrefixEntryPoint::Vis, MetaVarKind::Expr => { - // `expr` should not match underscores. + // `expr` should not match underscores, let expressions, or inline const. The latter + // two are for [backwards compatibility][0]. // HACK: Macro expansion should not be done using "rollback and try another alternative". - // rustc [explicitly checks the next token][0]. - // [0]: https://github.com/rust-lang/rust/blob/f0c4da499/compiler/rustc_expand/src/mbe/macro_parser.rs#L576 + // rustc [explicitly checks the next token][1]. + // [0]: https://github.com/rust-lang/rust/issues/86730 + // [1]: https://github.com/rust-lang/rust/blob/f0c4da499/compiler/rustc_expand/src/mbe/macro_parser.rs#L576 match input.peek_n(0) { - Some(tt::TokenTree::Leaf(tt::Leaf::Ident(it))) if it.text == "_" => { + Some(tt::TokenTree::Leaf(tt::Leaf::Ident(it))) + if it.text == "_" || it.text == "let" || it.text == "const" => + { return ExpandResult::only_err(ExpandError::NoMatchingRule) } _ => {} |