Type mismatch helper not check is closure return block

[A4-Tacks]

Code

struct SmolStr;
const _: fn() = || {
    match Some(()) {
        Some(()) => (),
        None => return,
    };
    let _: String = {
        SmolStr
    };
};

Current output

error[E0308]: mismatched types
 --> src/lib.rs:8:9
  |
8 |         SmolStr
  |         ^^^^^^^ expected `String`, found `SmolStr`
  |
note: return type inferred to be `String` here
 --> src/lib.rs:5:17
  |
5 |         None => return,
  |                 ^^^^^^

Desired output

error[E0308]: mismatched types
 --> src/lib.rs:8:9
  |
8 |         SmolStr
  |         ^^^^^^^ expected `String`, found `SmolStr`
  |

Rationale and extra context

No response

Other cases

struct SmolStr;
const _: fn() = || {
    match Some(()) {
        Some(()) => (),
        None => return,
    };
    let _: String = SmolStr;
};

Rust Version

rustc 1.97.0-nightly (913e4bea8 2026-04-22)
binary: rustc
commit-hash: 913e4bea83424658d76712fee9c52452a3a9ef0e
commit-date: 2026-04-22
host: aarch64-unknown-linux-gnu
release: 1.97.0-nightly
LLVM version: 22.1.2

Anything else?

No response

[cijiugechu]

can also reproduce on the latest stable(1.95.0): playground

[cijiugechu]

Regressed nightly: 2022-09-17,
nightly-2022-09-16 output:

error[E0308]: mismatched types
 --> /data/exp/repos/rust/tmp-closure-type-mismatch.rs:8:9
  |
8 |         SmolStr
  |         ^^^^^^^ expected struct `String`, found struct `SmolStr`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.

Seems to point to #101753

[cijiugechu]

@rustbot label +S-has-bisection