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Auto merge of #17174 - Kohei316:fix-infer-async-block-with-tail-return-expr, r=Veykril
Fix: infer type of async block with tail return expr
Fixes #17106
The `infer_async_block` method calls the `infer_block` method internally, which returns the never type without coercion when `tail_expr` is `None` and `ctx.diverges` is `Diverges::Always`.This is the reason for the bug in this issue.
https://github.com/rust-lang/rust-analyzer/blob/cfce2bb46da62950a8b70ddb0b2a12332da1b1e1/crates/hir-ty/src/infer/expr.rs#L1411-L1413
This PR solves the bug by adding a process to coerce after calling `infer_block` method.
This code passes all the tests, including tests I added for this isuue, however, I am not sure if this solution is right. I think that this solution is an ad hoc solution. So, I would appreciate to have your review.
I apologize if I'm off the mark, but `infer_async_block` method should be rewritten to share code with the process of infering type of `expr::Closure` instead of the `infer_block` method. That way it will be closer to the infer process of rustc.
| -rw-r--r-- | crates/hir-ty/src/infer/expr.rs | 18 | ||||
| -rw-r--r-- | crates/ide/src/inlay_hints/bind_pat.rs | 26 |
2 files changed, 43 insertions, 1 deletions
diff --git a/crates/hir-ty/src/infer/expr.rs b/crates/hir-ty/src/infer/expr.rs index 38076fce8f..4c12786362 100644 --- a/crates/hir-ty/src/infer/expr.rs +++ b/crates/hir-ty/src/infer/expr.rs @@ -933,8 +933,24 @@ impl InferenceContext<'_> { let prev_ret_coercion = mem::replace(&mut self.return_coercion, Some(CoerceMany::new(ret_ty.clone()))); + // FIXME: We should handle async blocks like we handle closures + let expected = &Expectation::has_type(ret_ty); let (_, inner_ty) = self.with_breakable_ctx(BreakableKind::Border, None, None, |this| { - this.infer_block(tgt_expr, *id, statements, *tail, None, &Expectation::has_type(ret_ty)) + let ty = this.infer_block(tgt_expr, *id, statements, *tail, None, expected); + if let Some(target) = expected.only_has_type(&mut this.table) { + match this.coerce(Some(tgt_expr), &ty, &target) { + Ok(res) => res, + Err(_) => { + this.result.type_mismatches.insert( + tgt_expr.into(), + TypeMismatch { expected: target.clone(), actual: ty.clone() }, + ); + target + } + } + } else { + ty + } }); self.diverges = prev_diverges; diff --git a/crates/ide/src/inlay_hints/bind_pat.rs b/crates/ide/src/inlay_hints/bind_pat.rs index 0cb8c485b2..3311bb48ad 100644 --- a/crates/ide/src/inlay_hints/bind_pat.rs +++ b/crates/ide/src/inlay_hints/bind_pat.rs @@ -1120,4 +1120,30 @@ fn test() { "#, ); } + + #[test] + fn type_hints_async_block() { + check_types( + r#" +//- minicore: future +async fn main() { + let _x = async { 8_i32 }; + //^^ impl Future<Output = i32> +}"#, + ); + } + + #[test] + fn type_hints_async_block_with_tail_return_exp() { + check_types( + r#" +//- minicore: future +async fn main() { + let _x = async { + //^^ impl Future<Output = i32> + return 8_i32; + }; +}"#, + ); + } } |