Unnamed repository; edit this file 'description' to name the repository.
Auto merge of #13523 - lowr:fix/adjust-expectation-for-if, r=lnicola
fix: disregard type variable expectation for if expressions
Fixes #13522
As [the comment](https://github.com/rust-lang/rust-analyzer/blob/8142d1f606dc2e52b1d2b8992671e2bd73379f28/crates/hir-ty/src/infer.rs#L1087-L1090) on `Expectation::adjust_for_branches` explains:
> If the expected type is just a type variable, then don't use an expected type. Otherwise, we might write parts of the type when checking the 'then' block which are incompatible with the 'else' branch.
Note that we already use it in match expressions. I've added tests for them too nevertheless.
| -rw-r--r-- | crates/hir-ty/src/infer/expr.rs | 1 | ||||
| -rw-r--r-- | crates/hir-ty/src/tests/coercion.rs | 33 |
2 files changed, 34 insertions, 0 deletions
diff --git a/crates/hir-ty/src/infer/expr.rs b/crates/hir-ty/src/infer/expr.rs index f56108b26c..b1f4de8260 100644 --- a/crates/hir-ty/src/infer/expr.rs +++ b/crates/hir-ty/src/infer/expr.rs @@ -85,6 +85,7 @@ impl<'a> InferenceContext<'a> { let ty = match &self.body[tgt_expr] { Expr::Missing => self.err_ty(), &Expr::If { condition, then_branch, else_branch } => { + let expected = &expected.adjust_for_branches(&mut self.table); self.infer_expr( condition, &Expectation::has_type(TyKind::Scalar(Scalar::Bool).intern(Interner)), diff --git a/crates/hir-ty/src/tests/coercion.rs b/crates/hir-ty/src/tests/coercion.rs index d301595bcd..1abdb0be7f 100644 --- a/crates/hir-ty/src/tests/coercion.rs +++ b/crates/hir-ty/src/tests/coercion.rs @@ -123,6 +123,23 @@ fn test() { } #[test] +fn if_else_adjust_for_branches_discard_type_var() { + check_no_mismatches( + r#" +fn test() { + let f = || { + if true { + &"" + } else { + "" + } + }; +} +"#, + ); +} + +#[test] fn match_first_coerce() { check_no_mismatches( r#" @@ -183,6 +200,22 @@ fn test() { } #[test] +fn match_adjust_for_branches_discard_type_var() { + check_no_mismatches( + r#" +fn test() { + let f = || { + match 0i32 { + 0i32 => &"", + _ => "", + } + }; +} +"#, + ); +} + +#[test] fn return_coerce_unknown() { check_types( r" |