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Diffstat (limited to 'crates/mbe/src/expander/matcher.rs')
| -rw-r--r-- | crates/mbe/src/expander/matcher.rs | 31 |
1 files changed, 18 insertions, 13 deletions
diff --git a/crates/mbe/src/expander/matcher.rs b/crates/mbe/src/expander/matcher.rs index e69d7d14e2..90f56cc31d 100644 --- a/crates/mbe/src/expander/matcher.rs +++ b/crates/mbe/src/expander/matcher.rs @@ -69,7 +69,7 @@ use tt::{iter::TtIter, DelimSpan}; use crate::{ expander::{Binding, Bindings, ExpandResult, Fragment}, expect_fragment, - parser::{MetaVarKind, Op, RepeatKind, Separator}, + parser::{ExprKind, MetaVarKind, Op, RepeatKind, Separator}, ExpandError, ExpandErrorKind, MetaTemplate, ValueResult, }; @@ -769,23 +769,28 @@ fn match_meta_var( it.map(|it| tt::TokenTree::subtree_or_wrap(it, delim_span)).map(Fragment::Path) }); } - MetaVarKind::Expr => { - // `expr` should not match underscores, let expressions, or inline const. The latter - // two are for [backwards compatibility][0]. + MetaVarKind::Expr(expr) => { + // `expr_2021` should not match underscores, let expressions, or inline const. + // The latter two are for [backwards compatibility][0]. + // And `expr` also should not contain let expressions but may contain the other two + // since `Edition2024`. // HACK: Macro expansion should not be done using "rollback and try another alternative". // 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.sym == sym::underscore - || it.sym == sym::let_ - || it.sym == sym::const_ => - { - return ExpandResult::only_err(ExpandError::new( - it.span, - ExpandErrorKind::NoMatchingRule, - )) + Some(tt::TokenTree::Leaf(tt::Leaf::Ident(it))) => { + let is_err = if matches!(expr, ExprKind::Expr2021) { + it.sym == sym::underscore || it.sym == sym::let_ || it.sym == sym::const_ + } else { + it.sym == sym::let_ + }; + if is_err { + return ExpandResult::only_err(ExpandError::new( + it.span, + ExpandErrorKind::NoMatchingRule, + )); + } } _ => {} }; |