Possible to support #[rustc::minimum(1.27)] or the like?

[mathstuf]

Using attributes which are always-true or always-false under this would then warn/error about being a tautology. This would help make sure that as the minimum version is bumped, old code/checks go away.

It would also act as documentation for the minimum version allowed. (AFAIK, still waiting on that field in Cargo.toml).

[dtolnay]

Seems reasonable. I would accept a PR implementing this.

[mathstuf]

Looks like there's a merged RFC for this now, so I'll close this in preference for that.