Rollup merge of #97034 - fee1-dead-contrib:layout-hash, r=dtolnay

Implement `Hash` for `core::alloc::Layout`

This was brought up on [reddit](https://www.reddit.com/r/rust/comments/uoypui/the_standard_library_types_are_good_except_when/), and I don't see why Layout shouldn't implement `Hash`. Feel free to comment if I am wrong though :)

library/core/src/alloc/layout.rs

@@ -26,7 +26,7 @@ const fn size_align<T>() -> (usize, usize) {
 /// like this are met, use specific allocators with looser
 /// requirements, or use the more lenient `Allocator` interface.)
 #[stable(feature = "alloc_layout", since = "1.28.0")]
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[lang = "alloc_layout"]
 pub struct Layout {
     // size of the requested block of memory, measured in bytes.

library/core/src/mem/valid_align.rs

@@ -1,6 +1,6 @@
 use crate::convert::TryFrom;
 use crate::num::NonZeroUsize;
-use crate::{cmp, fmt, mem, num};
+use crate::{cmp, fmt, hash, mem, num};
 
 /// A type storing a `usize` which is a power of two, and thus
 /// represents a possible alignment in the rust abstract machine.
@@ -105,6 +105,13 @@ impl cmp::PartialOrd for ValidAlign {
     }
 }
 
+impl hash::Hash for ValidAlign {
+    #[inline]
+    fn hash<H: hash::Hasher>(&self, state: &mut H) {
+        self.as_nonzero().hash(state)
+    }
+}
+
 #[cfg(target_pointer_width = "16")]
 type ValidAlignEnum = ValidAlignEnum16;
 #[cfg(target_pointer_width = "32")]