Auto merge of #115694 - clarfonthey:std-hash-private, r=dtolnay

Add `std::hash::{DefaultHasher, RandomState}` exports (needs FCP)

This implements rust-lang/libs-team#267 to move the libstd hasher types to `std::hash` where they belong, instead of `std::collections::hash_map`.

<details><summary>The below no longer applies, but is kept for clarity.</summary>
This is a small refactor for #27242, which moves the definitions of `RandomState` and `DefaultHasher` into `std::hash`, but in a way that won't be noticed in the public API.

I've opened rust-lang/libs-team#267 as a formal ACP to move these directly into the root of `std::hash`, but for now, they're at least separated out from the collections code in a way that will make moving that around easier.

I decided to simply copy the rustdoc for `std::hash` from `core::hash` since I think it would be ideal for the two to diverge longer-term, especially if the ACP is accepted. However, I would be willing to factor them out into a common markdown document if that's preferred.
</details>

1 files changed, 2 insertions, 3 deletions

diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 42589012257..f716c0fe922 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -494,8 +494,6 @@ pub use core::convert;
 pub use core::default;
 #[stable(feature = "futures_api", since = "1.36.0")]
 pub use core::future;
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::hash;
 #[stable(feature = "core_hint", since = "1.27.0")]
 pub use core::hint;
 #[stable(feature = "i128", since = "1.26.0")]
@@ -565,6 +563,7 @@ pub mod env;
 pub mod error;
 pub mod ffi;
 pub mod fs;
+pub mod hash;
 pub mod io;
 pub mod net;
 pub mod num;
@@ -716,7 +715,7 @@ pub(crate) mod test_helpers {
     #[track_caller]
     pub(crate) fn test_rng() -> rand_xorshift::XorShiftRng {
         use core::hash::{BuildHasher, Hash, Hasher};
-        let mut hasher = crate::collections::hash_map::RandomState::new().build_hasher();
+        let mut hasher = crate::hash::RandomState::new().build_hasher();
         core::panic::Location::caller().hash(&mut hasher);
         let hc64 = hasher.finish();
         let seed_vec = hc64.to_le_bytes().into_iter().chain(0u8..8).collect::<Vec<u8>>();