Conditional compilation according manifest MSRV.

Conditional compilation according manifest MSRV.

Selectors

• #[rustversion_msrv::msrv]

  True on the call-site crate's rust-version field, i.e., its minimum supported Rust version (MSRV).

Use Cases

The motivating use case for the msrv macro in this crate is to ensure a stable compiler error output when running negative trybuild tests. Guarding your test function like this means you only need to update the .stderr files when you bump your MSRV, not (potentially) every stable release (or worse). Of course, try make sure that your CI is actually running an MSRV job in its set.

#[rustversion_msrv::msrv]
#[test]
fn trybuild() {
   // ...
}