E0499 error shouldn't suggest adding a semicolon when there already is one · Issue #133941 · rust-lang/rust (original) (raw)

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Description

Code

use std:📑:PhantomData;

struct Bar<'a>(PhantomData<&'a mut i32>);

impl<'a> Drop for Bar<'a> { fn drop(&mut self) {} }

struct Foo();

impl Foo { fn f(&mut self) -> Option<Bar<'_>> { None }

fn g(&mut self) {}

}

fn main() { let mut foo = Foo(); while let Some(_) = foo.f() { foo.g(); }; }

Current output

Compiling playground v0.0.1 (/playground) error[E0499]: cannot borrow foo as mutable more than once at a time --> src/main.rs:22:9 |

21 | while let Some(_) = foo.f() { | ------- | | | first mutable borrow occurs here | a temporary with access to the first borrow is created here ... 22 | foo.g(); | ^^^ second mutable borrow occurs here 23 | }; | - ... and the first borrow might be used here, when that temporary is dropped and runs the destructor for type Option<Bar<'_>> | help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped | 23 | };; | +

For more information about this error, try rustc --explain E0499. error: could not compile playground (bin "playground") due to 1 previous error

Desired output

Not have the help section since there already is a semicolon

Rationale and extra context

No response

Other cases

Rust Version

Tested on the Rust Playground with both stable 1.83.0 and 1.85.0-nightly 2024-12-04 acabb52 (sorry for the lack of the exact command you wanted, but see rust-lang/rust-playground#1043)

Anything else?