Remove rustc_args_required_const attribute Now that stdarch no longer needs it (thanks `@Amanieu!),` we can kill the `rustc_args_required_const` attribute. This means that lifetime extension of references to temporaries is the only remaining job that promotion is performing. :-) r? `@oli-obk` Fixes https://github.com/rust-lang/rust/issues/69493
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.