Rustc suggest `break` with value inside `while`

[Exonorid]

Code

pub fn a() {
    let a = while false {
        some_function()
    };
}

fn some_function() -> i32 {
    1
}

Current output

error[E0308]: mismatched types
 --> <source>:3:9
  |
2 |       let a = while false {
  |  _____________-
3 | |         some_function()
  | |         ^^^^^^^^^^^^^^^ expected `()`, found `i32`
4 | |     };
  | |_____- expected this to be `()`
  |
help: consider using a semicolon here
  |
3 |         some_function();
  |                        +
help: consider using a semicolon here
  |
4 |     };;
  |      +
help: you might have meant to break the loop with this value
  |
3 |         break some_function();
  |         +++++                +

Desired output

error[E0308]: mismatched types
 --> <source>:3:9
  |
2 |       let a = while false {
  |  _____________-
3 | |         some_function()
  | |         ^^^^^^^^^^^^^^^ expected `()`, found `i32`
4 | |     };
  | |_____- `while` loops can't produce a non-trivial (i.e. not `()`) value
  |
help: consider using a semicolon here
  |
3 |         some_function();
  |                        +

Rationale and extra context

The suggestion to add a second semicolon after the loop is evidently wrong, and the suggestion to replace the expression with a break expression may mislead the user into thinking that will solve the problem. I can see how it may be debatable how likely confusion from said second point is, but the compiler knows from the fact that it's in a while loop that adding break won't do anything, so I don't see a good reason not to change it.

Other cases

If the expression inside the block is not a function call, the suggestions to add a semicolon disappear.

Rust Version

rustc 1.92.0 (ded5c06cf 2025-12-08)
binary: rustc
commit-hash: ded5c06cf21d2b93bffd5d884aa6e96934ee4234
commit-date: 2025-12-08
host: x86_64-unknown-linux-gnu
release: 1.92.0
LLVM version: 21.1.3

Anything else?

No response

[eggyal]

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