UPDATE: We've decided to convert this warning into a hard error, but are still waiting for a PR to make that a reality. If you're interested in contributing, there are directions for writing such a PR available here.

This tracking issue pertains to a bug fix for #22889. The problem was that the compiler was accepting two inherent impls that both defined the same method, which creates an obvious ambiguity:

struct Foo;

impl Foo {
    fn id() {}
}

impl Foo {
    fn id() {}
}

The most obvious fix here is to give one method a distinct name, though sometimes there are other possible rewrites (e.g., one could rewrite the impls to use a double dispatch pattern).

Current status

• Forbid items with the same name from appearing in overlapping inherent impl blocks #31925 introduces the overlapping_inherent_impls lint as warn-by-default
• Make sufficiently old or low-impact compatibility lints deny-by-default #36894 makes the overlapping_inherent_impls lint deny-by-default
• PR ? makes the overlapping_inherent_impls lint a hard error