From 2b228ce31075811028c9447d2387ca037e4ac9ee Mon Sep 17 00:00:00 2001
From: bluurryy <164359728+bluurryy@users.noreply.github.com>
Date: Sun, 21 Sep 2025 01:42:06 +0200
Subject: [PATCH] Implement `Allocator` for `&mut A` where `A: Allocator +
 ?Sized`

---
 library/core/src/alloc/mod.rs | 55 +++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/library/core/src/alloc/mod.rs b/library/core/src/alloc/mod.rs
index 9d608d5e83c40..680b1ec105a22 100644
--- a/library/core/src/alloc/mod.rs
+++ b/library/core/src/alloc/mod.rs
@@ -421,3 +421,58 @@ where
         unsafe { (**self).shrink(ptr, old_layout, new_layout) }
     }
 }
+
+#[unstable(feature = "allocator_api", issue = "32838")]
+unsafe impl<A> Allocator for &mut A
+where
+    A: Allocator + ?Sized,
+{
+    #[inline]
+    fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
+        (**self).allocate(layout)
+    }
+
+    #[inline]
+    fn allocate_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
+        (**self).allocate_zeroed(layout)
+    }
+
+    #[inline]
+    unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
+        // SAFETY: the safety contract must be upheld by the caller
+        unsafe { (**self).deallocate(ptr, layout) }
+    }
+
+    #[inline]
+    unsafe fn grow(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        // SAFETY: the safety contract must be upheld by the caller
+        unsafe { (**self).grow(ptr, old_layout, new_layout) }
+    }
+
+    #[inline]
+    unsafe fn grow_zeroed(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        // SAFETY: the safety contract must be upheld by the caller
+        unsafe { (**self).grow_zeroed(ptr, old_layout, new_layout) }
+    }
+
+    #[inline]
+    unsafe fn shrink(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        // SAFETY: the safety contract must be upheld by the caller
+        unsafe { (**self).shrink(ptr, old_layout, new_layout) }
+    }
+}