Auto merge of #118390 - cuviper:beta-next, r=cuviper

[beta] backports

- feat: implement `DoubleEndedSearcher` for `CharArray[Ref]Searcher` #111922
- Update to LLVM 17.0.5 #117907
- clarify `fn discriminant` guarantees: only free lifetimes may get erased #118006

r? ghost

library/core/src/mem/mod.rs

@@ -1132,10 +1132,12 @@ impl<T> fmt::Debug for Discriminant<T> {
 ///
 /// [Reference]: ../../reference/items/enumerations.html#custom-discriminant-values-for-fieldless-enumerations
 ///
-/// The value of a [`Discriminant<T>`] is independent of any *lifetimes* in `T`. As such, reading
-/// or writing a `Discriminant<Foo<'a>>` as a `Discriminant<Foo<'b>>` (whether via [`transmute`] or
-/// otherwise) is always sound. Note that this is **not** true for other kinds of generic
-/// parameters; `Discriminant<Foo<A>>` and `Discriminant<Foo<B>>` might be incompatible.
+/// The value of a [`Discriminant<T>`] is independent of any *free lifetimes* in `T`. As such,
+/// reading or writing a `Discriminant<Foo<'a>>` as a `Discriminant<Foo<'b>>` (whether via
+/// [`transmute`] or otherwise) is always sound. Note that this is **not** true for other kinds
+/// of generic parameters and for higher-ranked lifetimes; `Discriminant<Foo<A>>` and
+/// `Discriminant<Foo<B>>` as well as `Discriminant<Bar<dyn for<'a> Trait<'a>>>` and
+/// `Discriminant<Bar<dyn Trait<'static>>>` may be incompatible.
 ///
 /// # Examples
 ///

library/core/src/str/pattern.rs

@@ -806,6 +806,8 @@ unsafe impl<'a, const N: usize> ReverseSearcher<'a> for CharArraySearcher<'a, N>
     searcher_methods!(reverse);
 }
 
+impl<'a, const N: usize> DoubleEndedSearcher<'a> for CharArraySearcher<'a, N> {}
+
 /// Searches for chars that are equal to any of the [`char`]s in the array.
 ///
 /// # Examples
@@ -826,6 +828,8 @@ unsafe impl<'a, 'b, const N: usize> ReverseSearcher<'a> for CharArrayRefSearcher
     searcher_methods!(reverse);
 }
 
+impl<'a, 'b, const N: usize> DoubleEndedSearcher<'a> for CharArrayRefSearcher<'a, 'b, N> {}
+
 /////////////////////////////////////////////////////////////////////////////
 // Impl for &[char]
 /////////////////////////////////////////////////////////////////////////////