$ cargo run Compiling patterns v0.1.0 (file:///projects/patterns) error[E0005]: refutable pattern in local binding --> src/main.rs:3:9 | 3 | let Some(x) = some_option_value; | ^^^^^^^ 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/ch18-02-refutability.html = note: the matched value is of type `Option` help: you might want to use `let else` to handle the variant that isn't matched | 3 | let Some(x) = some_option_value else { todo!() }; | ++++++++++++++++ For more information about this error, try `rustc --explain E0005`. error: could not compile `patterns` (bin "patterns") due to 1 previous error