From 3c9a7491c2e2f54fa0ea59246c798017fcb8ce3f Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Tue, 4 Jul 2023 04:05:44 -0400
Subject: [PATCH 1/2] Add a test for `PartialEq` across `Allocator`s breaking
 inference (#113283)

Verify that `PartialEq` implementations do not break type inference
when comparing types across different allocators. This catches a
regression in current nightly introduced in 001b081cc1b (alloc: Allow
comparing `Box`s over different allocators")

`Box` is the only type that currently impelements this, but tests are
included for `Rc` and `Arc` to prevent future regresssions.
---
 .../issue-113283-alllocator-trait-eq.rs        | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 tests/ui/type-inference/issue-113283-alllocator-trait-eq.rs

diff --git a/tests/ui/type-inference/issue-113283-alllocator-trait-eq.rs b/tests/ui/type-inference/issue-113283-alllocator-trait-eq.rs
new file mode 100644
index 0000000000000..5d0e456d9ddc0
--- /dev/null
+++ b/tests/ui/type-inference/issue-113283-alllocator-trait-eq.rs
@@ -0,0 +1,18 @@
+// run-pass
+// Verify that PartialEq implementations do not break type inference when
+// accepting types with different allocators
+
+use std::rc::Rc;
+use std::sync::Arc;
+
+
+fn main() {
+    let boxed: Vec<Box<i32>> = vec![];
+    assert_eq!(boxed, vec![]);
+
+    let rc: Vec<Rc<i32>> = vec![];
+    assert_eq!(rc, vec![]);
+
+    let arc: Vec<Arc<i32>> = vec![];
+    assert_eq!(arc, vec![]);
+}

From a635bf7a3ba121b20993ed3f24300d2b81f7e5c1 Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Tue, 4 Jul 2023 04:23:18 -0400
Subject: [PATCH 2/2] Revert "alloc: Allow comparing `Box`s over different
 allocators"

This reverts commit 001b081cc1bfd24657e2dccbd9c8289f9a9d67a5.

This change was done as the above commit introduces a regression in type
inference. Regression test located at
`tests/ui/type-inference/issue-113283-alllocator-trait-eq.rs`
---
 library/alloc/src/boxed.rs | 35 +++++++++--------------------------
 1 file changed, 9 insertions(+), 26 deletions(-)

diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index fa23367593dbc..8ef2bac9282cd 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -1319,56 +1319,39 @@ impl Clone for Box<str> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A1, A2> PartialEq<Box<T, A2>> for Box<T, A1>
-where
-    T: ?Sized + PartialEq,
-    A1: Allocator,
-    A2: Allocator,
-{
+impl<T: ?Sized + PartialEq, A: Allocator> PartialEq for Box<T, A> {
     #[inline]
-    fn eq(&self, other: &Box<T, A2>) -> bool {
+    fn eq(&self, other: &Self) -> bool {
         PartialEq::eq(&**self, &**other)
     }
-
     #[inline]
-    fn ne(&self, other: &Box<T, A2>) -> bool {
+    fn ne(&self, other: &Self) -> bool {
         PartialEq::ne(&**self, &**other)
     }
 }
-
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, A1, A2> PartialOrd<Box<T, A2>> for Box<T, A1>
-where
-    T: ?Sized + PartialOrd,
-    A1: Allocator,
-    A2: Allocator,
-{
+impl<T: ?Sized + PartialOrd, A: Allocator> PartialOrd for Box<T, A> {
     #[inline]
-    fn partial_cmp(&self, other: &Box<T, A2>) -> Option<Ordering> {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
         PartialOrd::partial_cmp(&**self, &**other)
     }
-
     #[inline]
-    fn lt(&self, other: &Box<T, A2>) -> bool {
+    fn lt(&self, other: &Self) -> bool {
         PartialOrd::lt(&**self, &**other)
     }
-
     #[inline]
-    fn le(&self, other: &Box<T, A2>) -> bool {
+    fn le(&self, other: &Self) -> bool {
         PartialOrd::le(&**self, &**other)
     }
-
     #[inline]
-    fn ge(&self, other: &Box<T, A2>) -> bool {
+    fn ge(&self, other: &Self) -> bool {
         PartialOrd::ge(&**self, &**other)
     }
-
     #[inline]
-    fn gt(&self, other: &Box<T, A2>) -> bool {
+    fn gt(&self, other: &Self) -> bool {
         PartialOrd::gt(&**self, &**other)
     }
 }
-
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized + Ord, A: Allocator> Ord for Box<T, A> {
     #[inline]