error[E0005]: refutable pattern in local binding --> $DIR/feature-gate-exhaustive-patterns.rs:8:9 | LL | let Ok(_x) = foo(); | ^^^^^^ pattern `Err(_)` 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/ch18-02-refutability.html = note: the matched value is of type `Result` help: you might want to use `let else` to handle the variant that isn't matched | LL | let Ok(_x) = foo() else { todo!() }; | ++++++++++++++++ error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0005`.