Auto merge of #68529 - TimDiekmann:rename-alloc, r=Amanieu

Rename `Alloc` to `AllocRef`

The allocator-wg has decided to merge this change upstream in https://github.com/rust-lang/wg-allocators/issues/8#issuecomment-577122958.

This renames `Alloc` to `AllocRef` because types that implement `Alloc` are a reference, smart pointer, or ZSTs. It is not possible to have an allocator like `MyAlloc([u8; N])`, that owns the memory and also implements `Alloc`, since that would mean, that moving a `Vec<T, MyAlloc>` would need to correct the internal pointer, which is not possible as we don't have move constructors.

For further explanation please see https://github.com/rust-lang/wg-allocators/issues/8#issuecomment-489464843 and the comments after that one.

Additionally it clarifies the semantics of `Clone` on an allocator. In the case of `AllocRef`, it is clear that the cloned handle still points to the same allocator instance, and that you can free data allocated from one handle with another handle.

The initial proposal was to rename `Alloc` to `AllocHandle`, but `Ref` expresses the semantics better than `Handle`. Also, the only appearance of `Handle` in `std` are for windows specific resources, which might be confusing.

Blocked on https://github.com/rust-lang/miri/pull/1160

8 files changed, 26 insertions, 26 deletions

diff --git a/src/liballoc/alloc.rs b/src/liballoc/alloc.rs
index 0c0dc928b95..9fb0de63e6f 100644
--- a/src/liballoc/alloc.rs
+++ b/src/liballoc/alloc.rs
@@ -31,14 +31,14 @@ extern "Rust" {
 
 /// The global memory allocator.
 ///
-/// This type implements the [`Alloc`] trait by forwarding calls
+/// This type implements the [`AllocRef`] trait by forwarding calls
 /// to the allocator registered with the `#[global_allocator]` attribute
 /// if there is one, or the `std` crate’s default.
 ///
 /// Note: while this type is unstable, the functionality it provides can be
 /// accessed through the [free functions in `alloc`](index.html#functions).
 ///
-/// [`Alloc`]: trait.Alloc.html
+/// [`AllocRef`]: trait.AllocRef.html
 #[unstable(feature = "allocator_api", issue = "32838")]
 #[derive(Copy, Clone, Default, Debug)]
 pub struct Global;
@@ -50,14 +50,14 @@ pub struct Global;
 /// if there is one, or the `std` crate’s default.
 ///
 /// This function is expected to be deprecated in favor of the `alloc` method
-/// of the [`Global`] type when it and the [`Alloc`] trait become stable.
+/// of the [`Global`] type when it and the [`AllocRef`] trait become stable.
 ///
 /// # Safety
 ///
 /// See [`GlobalAlloc::alloc`].
 ///
 /// [`Global`]: struct.Global.html
-/// [`Alloc`]: trait.Alloc.html
+/// [`AllocRef`]: trait.AllocRef.html
 /// [`GlobalAlloc::alloc`]: trait.GlobalAlloc.html#tymethod.alloc
 ///
 /// # Examples
@@ -88,14 +88,14 @@ pub unsafe fn alloc(layout: Layout) -> *mut u8 {
 /// if there is one, or the `std` crate’s default.
 ///
 /// This function is expected to be deprecated in favor of the `dealloc` method
-/// of the [`Global`] type when it and the [`Alloc`] trait become stable.
+/// of the [`Global`] type when it and the [`AllocRef`] trait become stable.
 ///
 /// # Safety
 ///
 /// See [`GlobalAlloc::dealloc`].
 ///
 /// [`Global`]: struct.Global.html
-/// [`Alloc`]: trait.Alloc.html
+/// [`AllocRef`]: trait.AllocRef.html
 /// [`GlobalAlloc::dealloc`]: trait.GlobalAlloc.html#tymethod.dealloc
 #[stable(feature = "global_alloc", since = "1.28.0")]
 #[inline]
@@ -110,14 +110,14 @@ pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) {
 /// if there is one, or the `std` crate’s default.
 ///
 /// This function is expected to be deprecated in favor of the `realloc` method
-/// of the [`Global`] type when it and the [`Alloc`] trait become stable.
+/// of the [`Global`] type when it and the [`AllocRef`] trait become stable.
 ///
 /// # Safety
 ///
 /// See [`GlobalAlloc::realloc`].
 ///
 /// [`Global`]: struct.Global.html
-/// [`Alloc`]: trait.Alloc.html
+/// [`AllocRef`]: trait.AllocRef.html
 /// [`GlobalAlloc::realloc`]: trait.GlobalAlloc.html#method.realloc
 #[stable(feature = "global_alloc", since = "1.28.0")]
 #[inline]
@@ -132,14 +132,14 @@ pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8
 /// if there is one, or the `std` crate’s default.
 ///
 /// This function is expected to be deprecated in favor of the `alloc_zeroed` method
-/// of the [`Global`] type when it and the [`Alloc`] trait become stable.
+/// of the [`Global`] type when it and the [`AllocRef`] trait become stable.
 ///
 /// # Safety
 ///
 /// See [`GlobalAlloc::alloc_zeroed`].
 ///
 /// [`Global`]: struct.Global.html
-/// [`Alloc`]: trait.Alloc.html
+/// [`AllocRef`]: trait.AllocRef.html
 /// [`GlobalAlloc::alloc_zeroed`]: trait.GlobalAlloc.html#method.alloc_zeroed
 ///
 /// # Examples
@@ -163,7 +163,7 @@ pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 {
 }
 
 #[unstable(feature = "allocator_api", issue = "32838")]
-unsafe impl Alloc for Global {
+unsafe impl AllocRef for Global {
     #[inline]
     unsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr> {
         NonNull::new(alloc(layout)).ok_or(AllocErr)
diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index 87a4924f9be..8735c2c8f36 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -145,7 +145,7 @@ use core::ptr::{self, NonNull, Unique};
 use core::slice;
 use core::task::{Context, Poll};
 
-use crate::alloc::{self, Alloc, Global};
+use crate::alloc::{self, AllocRef, Global};
 use crate::raw_vec::RawVec;
 use crate::str::from_boxed_utf8_unchecked;
 use crate::vec::Vec;
diff --git a/src/liballoc/collections/btree/node.rs b/src/liballoc/collections/btree/node.rs
index d9cdebb4f73..c0a96e89366 100644
--- a/src/liballoc/collections/btree/node.rs
+++ b/src/liballoc/collections/btree/node.rs
@@ -36,7 +36,7 @@ use core::mem::{self, MaybeUninit};
 use core::ptr::{self, NonNull, Unique};
 use core::slice;
 
-use crate::alloc::{Alloc, Global, Layout};
+use crate::alloc::{AllocRef, Global, Layout};
 use crate::boxed::Box;
 
 const B: usize = 6;
diff --git a/src/liballoc/raw_vec.rs b/src/liballoc/raw_vec.rs
index 86aed612efe..e1b549bed18 100644
--- a/src/liballoc/raw_vec.rs
+++ b/src/liballoc/raw_vec.rs
@@ -7,7 +7,7 @@ use core::ops::Drop;
 use core::ptr::{self, NonNull, Unique};
 use core::slice;
 
-use crate::alloc::{handle_alloc_error, Alloc, AllocErr, Global, Layout};
+use crate::alloc::{handle_alloc_error, AllocErr, AllocRef, Global, Layout};
 use crate::boxed::Box;
 use crate::collections::TryReserveError::{self, *};
 
@@ -42,13 +42,13 @@ mod tests;
 /// field. This allows zero-sized types to not be special-cased by consumers of
 /// this type.
 #[allow(missing_debug_implementations)]
-pub struct RawVec<T, A: Alloc = Global> {
+pub struct RawVec<T, A: AllocRef = Global> {
     ptr: Unique<T>,
     cap: usize,
     a: A,
 }
 
-impl<T, A: Alloc> RawVec<T, A> {
+impl<T, A: AllocRef> RawVec<T, A> {
     /// Like `new`, but parameterized over the choice of allocator for
     /// the returned `RawVec`.
     pub const fn new_in(a: A) -> Self {
@@ -147,7 +147,7 @@ impl<T> RawVec<T, Global> {
     }
 }
 
-impl<T, A: Alloc> RawVec<T, A> {
+impl<T, A: AllocRef> RawVec<T, A> {
     /// Reconstitutes a `RawVec` from a pointer, capacity, and allocator.
     ///
     /// # Undefined Behavior
@@ -182,7 +182,7 @@ impl<T> RawVec<T, Global> {
     }
 }
 
-impl<T, A: Alloc> RawVec<T, A> {
+impl<T, A: AllocRef> RawVec<T, A> {
     /// Gets a raw pointer to the start of the allocation. Note that this is
     /// `Unique::empty()` if `capacity == 0` or `T` is zero-sized. In the former case, you must
     /// be careful.
@@ -622,7 +622,7 @@ enum ReserveStrategy {
 
 use ReserveStrategy::*;
 
-impl<T, A: Alloc> RawVec<T, A> {
+impl<T, A: AllocRef> RawVec<T, A> {
     fn reserve_internal(
         &mut self,
         used_capacity: usize,
@@ -700,7 +700,7 @@ impl<T> RawVec<T, Global> {
     }
 }
 
-impl<T, A: Alloc> RawVec<T, A> {
+impl<T, A: AllocRef> RawVec<T, A> {
     /// Frees the memory owned by the `RawVec` *without* trying to drop its contents.
     pub unsafe fn dealloc_buffer(&mut self) {
         let elem_size = mem::size_of::<T>();
@@ -712,7 +712,7 @@ impl<T, A: Alloc> RawVec<T, A> {
     }
 }
 
-unsafe impl<#[may_dangle] T, A: Alloc> Drop for RawVec<T, A> {
+unsafe impl<#[may_dangle] T, A: AllocRef> Drop for RawVec<T, A> {
     /// Frees the memory owned by the `RawVec` *without* trying to drop its contents.
     fn drop(&mut self) {
         unsafe {
diff --git a/src/liballoc/raw_vec/tests.rs b/src/liballoc/raw_vec/tests.rs
index b214cef3011..63087501f0e 100644
--- a/src/liballoc/raw_vec/tests.rs
+++ b/src/liballoc/raw_vec/tests.rs
@@ -19,7 +19,7 @@ fn allocator_param() {
     struct BoundedAlloc {
         fuel: usize,
     }
-    unsafe impl Alloc for BoundedAlloc {
+    unsafe impl AllocRef for BoundedAlloc {
         unsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr> {
             let size = layout.size();
             if size > self.fuel {
diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index b176e0f6e2a..9dc5447397f 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -252,7 +252,7 @@ use core::ptr::{self, NonNull};
 use core::slice::{self, from_raw_parts_mut};
 use core::usize;
 
-use crate::alloc::{box_free, handle_alloc_error, Alloc, Global, Layout};
+use crate::alloc::{box_free, handle_alloc_error, AllocRef, Global, Layout};
 use crate::string::String;
 use crate::vec::Vec;
 
diff --git a/src/liballoc/sync.rs b/src/liballoc/sync.rs
index 4aa0190b149..fd285242d5b 100644
--- a/src/liballoc/sync.rs
+++ b/src/liballoc/sync.rs
@@ -25,7 +25,7 @@ use core::sync::atomic;
 use core::sync::atomic::Ordering::{Acquire, Relaxed, Release, SeqCst};
 use core::{isize, usize};
 
-use crate::alloc::{box_free, handle_alloc_error, Alloc, Global, Layout};
+use crate::alloc::{box_free, handle_alloc_error, AllocRef, Global, Layout};
 use crate::boxed::Box;
 use crate::rc::is_dangling;
 use crate::string::String;
diff --git a/src/liballoc/tests/heap.rs b/src/liballoc/tests/heap.rs
index 43cd7187823..7fcfcf9b294 100644
--- a/src/liballoc/tests/heap.rs
+++ b/src/liballoc/tests/heap.rs
@@ -1,4 +1,4 @@
-use std::alloc::{Alloc, Global, Layout, System};
+use std::alloc::{AllocRef, Global, Layout, System};
 
 /// Issue #45955 and #62251.
 #[test]
@@ -11,7 +11,7 @@ fn std_heap_overaligned_request() {
     check_overalign_requests(Global)
 }
 
-fn check_overalign_requests<T: Alloc>(mut allocator: T) {
+fn check_overalign_requests<T: AllocRef>(mut allocator: T) {
     for &align in &[4, 8, 16, 32] {
         // less than and bigger than `MIN_ALIGN`
         for &size in &[align / 2, align - 1] {