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Auto merge of #13027 - jonas-schievink:fix-mismatch-with-trailing-empty-macro, r=jonas-schievink
fix: Fix incorrect type mismatch with `cfg_if!` and other macros in expression position
Fixes https://github.com/rust-lang/rust-analyzer/issues/12940
This is a bit of a hack, ideally `MacroStmts` would not exist at all after HIR lowering, but that requires changing how the lowering code works.
| -rw-r--r-- | crates/hir-def/src/body/lower.rs | 10 | ||||
| -rw-r--r-- | crates/hir-ty/src/tests/regression.rs | 17 |
2 files changed, 26 insertions, 1 deletions
diff --git a/crates/hir-def/src/body/lower.rs b/crates/hir-def/src/body/lower.rs index 66f9c24e87..f6ec8bf7e9 100644 --- a/crates/hir-def/src/body/lower.rs +++ b/crates/hir-def/src/body/lower.rs @@ -551,9 +551,17 @@ impl ExprCollector<'_> { } } ast::Expr::MacroStmts(e) => { - let statements = e.statements().filter_map(|s| self.collect_stmt(s)).collect(); + let statements: Box<[_]> = + e.statements().filter_map(|s| self.collect_stmt(s)).collect(); let tail = e.expr().map(|e| self.collect_expr(e)); + if e.syntax().children().next().is_none() { + // HACK: make sure that macros that expand to nothing aren't treated as a `()` + // expression when used in block tail position. + cov_mark::hit!(empty_macro_in_trailing_position_is_removed); + return None; + } + self.alloc_expr(Expr::MacroStmts { tail, statements }, syntax_ptr) } ast::Expr::UnderscoreExpr(_) => self.alloc_expr(Expr::Underscore, syntax_ptr), diff --git a/crates/hir-ty/src/tests/regression.rs b/crates/hir-ty/src/tests/regression.rs index 93a88ab58e..1b5ed0603b 100644 --- a/crates/hir-ty/src/tests/regression.rs +++ b/crates/hir-ty/src/tests/regression.rs @@ -1648,3 +1648,20 @@ fn main() { "#]], ); } + +#[test] +fn trailing_empty_macro() { + cov_mark::check!(empty_macro_in_trailing_position_is_removed); + check_no_mismatches( + r#" +macro_rules! m2 { + ($($t:tt)*) => {$($t)*}; +} + +fn macrostmts() -> u8 { + m2! { 0 } + m2! {} +} + "#, + ); +} |