Rollup merge of #58553 - scottmcm:more-ihle, r=Centril

Use more impl header lifetime elision

Inspired by seeing explicit lifetimes on these two:

- https://doc.rust-lang.org/nightly/std/slice/struct.Iter.html#impl-FusedIterator
- https://doc.rust-lang.org/nightly/std/primitive.u32.html#impl-Not

And a follow-up to https://github.com/rust-lang/rust/pull/54687, that started using IHLE in libcore.

Most of the changes in here fall into two big categories:

- Removing lifetimes from common traits that can essentially never user a lifetime from an input (particularly `Drop`, `Debug`, and `Clone`)

- Forwarding impls that are only possible because the lifetime doesn't matter (like `impl<R: Read + ?Sized> Read for &mut R`)

I omitted things that seemed like they could be more controversial, like the handful of iterators that have a `Item: 'static` despite the iterator having a lifetime or the `PartialEq` implementations [where the flipped one cannot elide the lifetime](https://internals.rust-lang.org/t/impl-type-parameter-aliases/9403/2?u=scottmcm).

I also removed two lifetimes that turned out to be completely unused; see https://github.com/rust-lang/rust/issues/41960#issuecomment-464557423

1 files changed, 1 insertions, 1 deletions

diff --git a/src/liballoc/vec.rs b/src/liballoc/vec.rs
index 57723e4d212..a351d482fed 100644
--- a/src/liballoc/vec.rs
+++ b/src/liballoc/vec.rs
@@ -2455,7 +2455,7 @@ pub struct Drain<'a, T: 'a> {
 }
 
 #[stable(feature = "collection_debug", since = "1.17.0")]
-impl<'a, T: 'a + fmt::Debug> fmt::Debug for Drain<'a, T> {
+impl<T: fmt::Debug> fmt::Debug for Drain<'_, T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_tuple("Drain")
          .field(&self.iter.as_slice())