Matching on usize requires half-open range #146476
Description
usize ranges in match statements are surprising:
fn test(i: usize) { match i { 0..=usize::MAX => todo!(), } }I expected this to compile; instead, rustc returns an error:
error[E0004]: non-exhaustive patterns: `usize::MAX..` not covered --> src/lib.rs:2:11 | 2 | match i { | ^ pattern `usize::MAX..` not covered | = note: the matched value is of type `usize` = note: `usize` does not have a fixed maximum value, so half-open ranges are necessary to match exhaustively help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown | 3 ~ 0..=usize::MAX => todo!(), 4 ~ usize::MAX.. => todo!(), | For more information about this error, try `rustc --explain E0004`. This is obviously a known edge case, given the custom error message (which is great!), but it's still a weird paper cut. It's especially weird to declare "usize does not have a fixed maximum value" when usize::MAX is right there!
Doing a little digging, it looks like it dates back to at least #118598
Meta
rustc --version --verbose:
rustc 1.89.0 (29483883e 2025-08-04) binary: rustc commit-hash: 29483883eed69d5fb4db01964cdf2af4d86e9cb2 commit-date: 2025-08-04 host: aarch64-apple-darwin release: 1.89.0 LLVM version: 20.1.7