rust-lang / rust-lang/rust

Rust suggests adding `else` to non-let assignment.

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@xizheyin is already working on this.

Since Aug 18, 2025.

A-diagnostics T-compiler
Dominant language
Rust
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Description

Code
fn main() {
    let mut x = 1;
    Some(x) = Some(1);
}
Current output
error[E0005]: refutable pattern in local binding
 --> src/main.rs:3:5
  |
3 |     Some(x) = Some(1);
  |     ^^^^^^^ pattern `None` not covered
  |
  = note: `let` bindings require an "irrefutable pattern", like a `struct` or an `enum` with only one variant
  = note: for more information, visit https://doc.rust-lang.org/book/ch19-02-refutability.html
  = note: the matched value is of type `Option<i32>`
help: you might want to use `let else` to handle the variant that isn't matched
  |
3 |     Some(x) = Some(1) else { todo!() };
  |                       ++++++++++++++++

For more information about this error, try `rustc --explain E0005`.
error: could not compile `playground` (bin "playground") due to 1 previous error
Desired output

Rationale and extra context

Adding the else as suggested results in a parse error.

Other cases

Rust Version
Reproducible on the playground with version 1.91.0-nightly (2025-08-16 2e2642e641a941f0a140)
Anything else?

No response

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