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Diagnostic suggests changing &mut vec![1] to mut vec![1] #143523

@theemathas

Description

@theemathas

Code

trait Trait {}

impl Trait for Vec<i32> {}

fn foo(_: impl Trait) {}

fn main() {
    foo(&mut vec![1]);
}

Current output

error[E0277]: the trait bound `&mut Vec<{integer}>: Trait` is not satisfied
 --> src/main.rs:8:9
  |
8 |     foo(&mut vec![1]);
  |     --- ^^^^^^^^^^^^ the trait `Trait` is not implemented for `&mut Vec<{integer}>`
  |     |
  |     required by a bound introduced by this call
  |
note: required by a bound in `foo`
 --> src/main.rs:5:16
  |
5 | fn foo(_: impl Trait) {}
  |                ^^^^^ required by this bound in `foo`
help: consider removing the leading `&`-reference
  |
8 -     foo(&mut vec![1]);
8 +     foo(mut vec![1]);
  |

For more information about this error, try `rustc --explain E0277`.
error: could not compile `playground` (bin "playground") due to 1 previous error

Desired output

error[E0277]: the trait bound `&mut Vec<{integer}>: Trait` is not satisfied
 --> src/main.rs:8:9
  |
8 |     foo(&mut vec![1]);
  |     --- ^^^^^^^^^^^^ the trait `Trait` is not implemented for `&mut Vec<{integer}>`
  |     |
  |     required by a bound introduced by this call
  |
note: required by a bound in `foo`
 --> src/main.rs:5:16
  |
5 | fn foo(_: impl Trait) {}
  |                ^^^^^ required by this bound in `foo`
help: consider removing the leading `&mut`-reference
  |
8 -     foo(&mut vec![1]);
8 +     foo(vec![1]);
  |

For more information about this error, try `rustc --explain E0277`.
error: could not compile `playground` (bin "playground") due to 1 previous error

Rationale and extra context

The suggested mut vec![] is invalid. The presence of the trait and the presence of the vec macro seem to both be required for this bug to occur.

Other cases

Rust Version

Reproducible on the playground with 1.90.0-nightly (2025-07-05 5adb489a8034f7b56b29)

Anything else?

No response

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