Unsupported Rust: coroutines (nightly)

[W95Psp]

We don't support coroutines, which are a nightly feature, and we don't plan on supporting them.

Example of code we reject:

#![feature(coroutines)]

fn f() {
    #[coroutine] || {
        yield 42u8;
    };
}

Open this code snippet in the playground