Accurately refer to assoc fn without receiver as assoc fn instead of methods.
Add `AssocItem::descr` method to centralize where we call methods and associated functions.
delegation: Implement glob delegation
Support delegating to all trait methods in one go.
Overriding globs with explicit definitions is also supported.
The implementation is generally based on the design from https://github.com/rust-lang/rfcs/pull/3530#issuecomment-2020869823, but unlike with list delegation in https://github.com/rust-lang/rust/pull/123413 we cannot expand glob delegation eagerly.
We have to enqueue it into the queue of unexpanded macros (most other macros are processed this way too), and then a glob delegation waits in that queue until its trait path is resolved, and enough code expands to generate the identifier list produced from the glob.
Glob delegation is only allowed in impls, and can only point to traits.
Supporting it in other places gives very little practical benefit, but significantly raises the implementation complexity.
Part of https://github.com/rust-lang/rust/issues/118212.
delegation: Fix hygiene for `self`
And fix diagnostics for `self` from a macro.
The missing rib caused `self` to be treated as a generic parameter and ignore `macro_rules` hygiene.
Addresses this comment https://github.com/rust-lang/rust/pull/124135#discussion_r1637492234.
Also allow `impl Trait` in delegated functions.
The delegation item will refer to the original opaque type from the callee, fresh opaque type won't be created.
Delegation: fix ICE on wrong `self` resolution
fixes https://github.com/rust-lang/rust/issues/122874
Delegation item should be wrapped in a `rib` to behave like a regular function during name resolution.
r? `@petrochenkov`
