Auto merge of #120486 - reitermarkus:use-generic-nonzero, r=dtolnay

Use generic `NonZero` internally.

Tracking issue: https://github.com/rust-lang/rust/issues/120257

compiler/rustc_data_structures/src/lib.rs

@@ -20,6 +20,7 @@
 #![feature(cfg_match)]
 #![feature(core_intrinsics)]
 #![feature(extend_one)]
+#![feature(generic_nonzero)]
 #![feature(hash_raw_entry)]
 #![feature(hasher_prefixfree_extras)]
 #![feature(lazy_cell)]

compiler/rustc_data_structures/src/stable_hasher.rs

@@ -6,6 +6,7 @@ use std::fmt;
 use std::hash::{BuildHasher, Hash, Hasher};
 use std::marker::PhantomData;
 use std::mem;
+use std::num::NonZero;
 
 #[cfg(test)]
 mod tests;
@@ -338,14 +339,14 @@ impl<CTX, T> HashStable<CTX> for PhantomData<T> {
     fn hash_stable(&self, _ctx: &mut CTX, _hasher: &mut StableHasher) {}
 }
 
-impl<CTX> HashStable<CTX> for ::std::num::NonZeroU32 {
+impl<CTX> HashStable<CTX> for NonZero<u32> {
     #[inline]
     fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
         self.get().hash_stable(ctx, hasher)
     }
 }
 
-impl<CTX> HashStable<CTX> for ::std::num::NonZeroUsize {
+impl<CTX> HashStable<CTX> for NonZero<usize> {
     #[inline]
     fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
         self.get().hash_stable(ctx, hasher)

compiler/rustc_data_structures/src/sync/worker_local.rs

@@ -1,7 +1,7 @@
 use parking_lot::Mutex;
 use std::cell::Cell;
 use std::cell::OnceCell;
-use std::num::NonZeroUsize;
+use std::num::NonZero;
 use std::ops::Deref;
 use std::ptr;
 use std::sync::Arc;
@@ -31,7 +31,7 @@ impl RegistryId {
 }
 
 struct RegistryData {
-    thread_limit: NonZeroUsize,
+    thread_limit: NonZero<usize>,
     threads: Mutex<usize>,
 }
 
@@ -61,7 +61,7 @@ thread_local! {
 
 impl Registry {
     /// Creates a registry which can hold up to `thread_limit` threads.
-    pub fn new(thread_limit: NonZeroUsize) -> Self {
+    pub fn new(thread_limit: NonZero<usize>) -> Self {
         Registry(Arc::new(RegistryData { thread_limit, threads: Mutex::new(0) }))
     }
 

compiler/rustc_data_structures/src/tagged_ptr/copy.rs

@@ -4,7 +4,7 @@ use std::fmt;
 use std::hash::{Hash, Hasher};
 use std::marker::PhantomData;
 use std::mem::ManuallyDrop;
-use std::num::NonZeroUsize;
+use std::num::NonZero;
 use std::ops::{Deref, DerefMut};
 use std::ptr::NonNull;
 
@@ -134,7 +134,7 @@ where
 
         ptr.map_addr(|addr| {
             // Safety:
-            // - The pointer is `NonNull` => it's address is `NonZeroUsize`
+            // - The pointer is `NonNull` => it's address is `NonZero<usize>`
             // - `P::BITS` least significant bits are always zero (`Pointer` contract)
             // - `T::BITS <= P::BITS` (from `Self::ASSERTION`)
             //
@@ -143,14 +143,14 @@ where
             // `{non_zero} | packed_tag` can't make the value zero.
 
             let packed = (addr.get() >> T::BITS) | packed_tag;
-            unsafe { NonZeroUsize::new_unchecked(packed) }
+            unsafe { NonZero::new_unchecked(packed) }
         })
     }
 
     /// Retrieves the original raw pointer from `self.packed`.
     #[inline]
     pub(super) fn pointer_raw(&self) -> NonNull<P::Target> {
-        self.packed.map_addr(|addr| unsafe { NonZeroUsize::new_unchecked(addr.get() << T::BITS) })
+        self.packed.map_addr(|addr| unsafe { NonZero::new_unchecked(addr.get() << T::BITS) })
     }
 
     /// This provides a reference to the `P` pointer itself, rather than the