Following my failed target_version RFC, there is one idea I want to salvage: allowing non-lang items to be deprecated.
Currently, this feature is restricted to
lang items APIs distributed with rustc, presumably because the
since field refers to rust version, but I see no point where this is actually checked.
Lifting the restriction seems easy enough, and it would open smoother upgrade paths for library writers.
So is there any technical reason other than “we didn’t get around to it yet” to keep this limitation? I know that I see enough use cases, does it need an RFC (considering the feature is already there, albeit restricted to lang items)?