From 9a170fedd792b3373ddf7b512cff0b1463ee30e0 Mon Sep 17 00:00:00 2001
From: Antoni Spaanderman <56turtle56@gmail.com>
Date: Fri, 2 Jan 2026 16:15:40 +0100
Subject: [PATCH] make specialization of Vec::extend and VecDeque::extend_front
 work for vec::IntoIter with any Allocator, not just Global

---
 .../alloc/src/collections/vec_deque/spec_extend.rs | 14 ++++++++------
 library/alloc/src/vec/spec_extend.rs               |  4 ++--
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/library/alloc/src/collections/vec_deque/spec_extend.rs b/library/alloc/src/collections/vec_deque/spec_extend.rs
index f73ba795cbea..b65e229361f2 100644
--- a/library/alloc/src/collections/vec_deque/spec_extend.rs
+++ b/library/alloc/src/collections/vec_deque/spec_extend.rs
@@ -77,8 +77,8 @@ where
 }
 
 #[cfg(not(test))]
-impl<T, A: Allocator> SpecExtend<T, vec::IntoIter<T>> for VecDeque<T, A> {
-    fn spec_extend(&mut self, mut iterator: vec::IntoIter<T>) {
+impl<T, A1: Allocator, A2: Allocator> SpecExtend<T, vec::IntoIter<T, A2>> for VecDeque<T, A1> {
+    fn spec_extend(&mut self, mut iterator: vec::IntoIter<T, A2>) {
         let slice = iterator.as_slice();
         self.reserve(slice.len());
 
@@ -153,9 +153,9 @@ where
 }
 
 #[cfg(not(test))]
-impl<T, A: Allocator> SpecExtendFront<T, vec::IntoIter<T>> for VecDeque<T, A> {
+impl<T, A1: Allocator, A2: Allocator> SpecExtendFront<T, vec::IntoIter<T, A2>> for VecDeque<T, A1> {
     #[track_caller]
-    fn spec_extend_front(&mut self, mut iterator: vec::IntoIter<T>) {
+    fn spec_extend_front(&mut self, mut iterator: vec::IntoIter<T, A2>) {
         let slice = iterator.as_slice();
         // SAFETY: elements in the slice are forgotten after this call
         unsafe { prepend_reversed(self, slice) };
@@ -164,9 +164,11 @@ impl<T, A: Allocator> SpecExtendFront<T, vec::IntoIter<T>> for VecDeque<T, A> {
 }
 
 #[cfg(not(test))]
-impl<T, A: Allocator> SpecExtendFront<T, Rev<vec::IntoIter<T>>> for VecDeque<T, A> {
+impl<T, A1: Allocator, A2: Allocator> SpecExtendFront<T, Rev<vec::IntoIter<T, A2>>>
+    for VecDeque<T, A1>
+{
     #[track_caller]
-    fn spec_extend_front(&mut self, iterator: Rev<vec::IntoIter<T>>) {
+    fn spec_extend_front(&mut self, iterator: Rev<vec::IntoIter<T, A2>>) {
         let mut iterator = iterator.into_inner();
         let slice = iterator.as_slice();
         // SAFETY: elements in the slice are forgotten after this call
diff --git a/library/alloc/src/vec/spec_extend.rs b/library/alloc/src/vec/spec_extend.rs
index f5bcd3ec9d82..7c908841c90e 100644
--- a/library/alloc/src/vec/spec_extend.rs
+++ b/library/alloc/src/vec/spec_extend.rs
@@ -28,8 +28,8 @@ where
     }
 }
 
-impl<T, A: Allocator> SpecExtend<T, IntoIter<T>> for Vec<T, A> {
-    fn spec_extend(&mut self, mut iterator: IntoIter<T>) {
+impl<T, A1: Allocator, A2: Allocator> SpecExtend<T, IntoIter<T, A2>> for Vec<T, A1> {
+    fn spec_extend(&mut self, mut iterator: IntoIter<T, A2>) {
         unsafe {
             self.append_elements(iterator.as_slice() as _);
         }