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, 7 insertions, 7 deletions

diff --git a/src/libstd/io/stdio.rs b/src/libstd/io/stdio.rs
index 4068c0f9c7d..0324568e6fb 100644
--- a/src/libstd/io/stdio.rs
+++ b/src/libstd/io/stdio.rs
@@ -312,7 +312,7 @@ impl Read for Stdin {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Read for StdinLock<'a> {
+impl Read for StdinLock<'_> {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         self.inner.read(buf)
     }
@@ -323,13 +323,13 @@ impl<'a> Read for StdinLock<'a> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> BufRead for StdinLock<'a> {
+impl BufRead for StdinLock<'_> {
     fn fill_buf(&mut self) -> io::Result<&[u8]> { self.inner.fill_buf() }
     fn consume(&mut self, n: usize) { self.inner.consume(n) }
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a> fmt::Debug for StdinLock<'a> {
+impl fmt::Debug for StdinLock<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.pad("StdinLock { .. }")
     }
@@ -485,7 +485,7 @@ impl Write for Stdout {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Write for StdoutLock<'a> {
+impl Write for StdoutLock<'_> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         self.inner.borrow_mut().write(buf)
     }
@@ -495,7 +495,7 @@ impl<'a> Write for StdoutLock<'a> {
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a> fmt::Debug for StdoutLock<'a> {
+impl fmt::Debug for StdoutLock<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.pad("StdoutLock { .. }")
     }
@@ -638,7 +638,7 @@ impl Write for Stderr {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Write for StderrLock<'a> {
+impl Write for StderrLock<'_> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         self.inner.borrow_mut().write(buf)
     }
@@ -648,7 +648,7 @@ impl<'a> Write for StderrLock<'a> {
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a> fmt::Debug for StderrLock<'a> {
+impl fmt::Debug for StderrLock<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.pad("StderrLock { .. }")
     }