Soft-deprecating something in the standard library with a clippy lint feels a bit off for me too; I think that if something in the standard library is going to

Soft-deprecating something in the standard library with a clippy lint feels a bit off for me too; I think that if something in the standard library is going to be discouraged, it should be done in the standard library itself (e.g. through documentation and/or using the deprecation warning). Clippy is absolutely phenomenal, but I tend not to think of it as something that's intended to be required by all users. Using it as a way to keep track of discouraged std types feels like it could easily lead to fragmentation where users stop looking to the standard library as the source of truth for its own contents.