Auto merge of #77187 - TimDiekmann:box-alloc, r=Amanieu

Support custom allocators in `Box`

r? `@Amanieu`

This pull request requires a crater run.

### Prior work:
- #71873
- #58457
- [`alloc-wg`](https://github.com/TimDiekmann/alloc-wg)-crate

Currently blocked on:
- ~#77118~
- ~https://github.com/rust-lang/chalk/issues/615 (#77515)~

24 files changed, 146 insertions, 65 deletions

diff --git a/src/test/mir-opt/inline/inline_into_box_place.main.Inline.32bit.diff b/src/test/mir-opt/inline/inline_into_box_place.main.Inline.32bit.diff
index f5c8ee134db..49fe14babc5 100644
--- a/src/test/mir-opt/inline/inline_into_box_place.main.Inline.32bit.diff
+++ b/src/test/mir-opt/inline/inline_into_box_place.main.Inline.32bit.diff
@@ -53,10 +53,10 @@
 -     }
 - 
 -     bb4 (cleanup): {
--         _3 = alloc::alloc::box_free::<Vec<u32>>(move (_2.0: std::ptr::Unique<std::vec::Vec<u32>>)) -> bb3; // scope 0 at $DIR/inline-into-box-place.rs:8:42: 8:43
+-         _3 = alloc::alloc::box_free::<Vec<u32>, std::alloc::Global>(move (_2.0: std::ptr::Unique<std::vec::Vec<u32>>), move (_2.1: std::alloc::Global)) -> bb3; // scope 0 at $DIR/inline-into-box-place.rs:8:42: 8:43
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-into-box-place.rs:8:42: 8:43
--                                          // + literal: Const { ty: unsafe fn(std::ptr::Unique<std::vec::Vec<u32>>) {alloc::alloc::box_free::<std::vec::Vec<u32>>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: unsafe fn(std::ptr::Unique<std::vec::Vec<u32>>, std::alloc::Global) {alloc::alloc::box_free::<std::vec::Vec<u32>, std::alloc::Global>}, val: Value(Scalar(<ZST>)) }
       }
   }
   
diff --git a/src/test/mir-opt/inline/inline_into_box_place.main.Inline.64bit.diff b/src/test/mir-opt/inline/inline_into_box_place.main.Inline.64bit.diff
index 5aeffa9c2a5..bb8ebc30cdd 100644
--- a/src/test/mir-opt/inline/inline_into_box_place.main.Inline.64bit.diff
+++ b/src/test/mir-opt/inline/inline_into_box_place.main.Inline.64bit.diff
@@ -53,10 +53,10 @@
 -     }
 - 
 -     bb4 (cleanup): {
--         _3 = alloc::alloc::box_free::<Vec<u32>>(move (_2.0: std::ptr::Unique<std::vec::Vec<u32>>)) -> bb3; // scope 0 at $DIR/inline-into-box-place.rs:8:42: 8:43
+-         _3 = alloc::alloc::box_free::<Vec<u32>, std::alloc::Global>(move (_2.0: std::ptr::Unique<std::vec::Vec<u32>>), move (_2.1: std::alloc::Global)) -> bb3; // scope 0 at $DIR/inline-into-box-place.rs:8:42: 8:43
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-into-box-place.rs:8:42: 8:43
--                                          // + literal: Const { ty: unsafe fn(std::ptr::Unique<std::vec::Vec<u32>>) {alloc::alloc::box_free::<std::vec::Vec<u32>>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: unsafe fn(std::ptr::Unique<std::vec::Vec<u32>>, std::alloc::Global) {alloc::alloc::box_free::<std::vec::Vec<u32>, std::alloc::Global>}, val: Value(Scalar(<ZST>)) }
       }
   }
   
diff --git a/src/test/ui/box/alloc-unstable-fail.rs b/src/test/ui/box/alloc-unstable-fail.rs
new file mode 100644
index 00000000000..9427571648c
--- /dev/null
+++ b/src/test/ui/box/alloc-unstable-fail.rs
@@ -0,0 +1,6 @@
+use std::boxed::Box;
+
+fn main() {
+    let _boxed: Box<u32, _> = Box::new(10);
+    //~^ ERROR use of unstable library feature 'allocator_api'
+}
diff --git a/src/test/ui/box/alloc-unstable-fail.stderr b/src/test/ui/box/alloc-unstable-fail.stderr
new file mode 100644
index 00000000000..03ae36e8890
--- /dev/null
+++ b/src/test/ui/box/alloc-unstable-fail.stderr
@@ -0,0 +1,12 @@
+error[E0658]: use of unstable library feature 'allocator_api'
+  --> $DIR/alloc-unstable-fail.rs:4:26
+   |
+LL |     let _boxed: Box<u32, _> = Box::new(10);
+   |                          ^
+   |
+   = note: see issue #32838 <https://github.com/rust-lang/rust/issues/32838> for more information
+   = help: add `#![feature(allocator_api)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/box/alloc-unstable.rs b/src/test/ui/box/alloc-unstable.rs
new file mode 100644
index 00000000000..66388d0d512
--- /dev/null
+++ b/src/test/ui/box/alloc-unstable.rs
@@ -0,0 +1,8 @@
+// run-pass
+#![feature(allocator_api)]
+
+use std::boxed::Box;
+
+fn main() {
+    let _boxed: Box<u32, _> = Box::new(10);
+}
diff --git a/src/test/ui/box-into-boxed-slice-fail.rs b/src/test/ui/box/into-boxed-slice-fail.rs
index 49dbb170f8e..49dbb170f8e 100644
--- a/src/test/ui/box-into-boxed-slice-fail.rs
+++ b/src/test/ui/box/into-boxed-slice-fail.rs
diff --git a/src/test/ui/box-into-boxed-slice-fail.stderr b/src/test/ui/box/into-boxed-slice-fail.stderr
index 8cfa3668d92..7a5ba16461f 100644
--- a/src/test/ui/box-into-boxed-slice-fail.stderr
+++ b/src/test/ui/box/into-boxed-slice-fail.stderr
@@ -1,14 +1,14 @@
 error[E0277]: the size for values of type `[u8]` cannot be known at compilation time
-  --> $DIR/box-into-boxed-slice-fail.rs:7:35
+  --> $DIR/into-boxed-slice-fail.rs:7:35
    |
 LL |     let _ = Box::into_boxed_slice(boxed_slice);
    |                                   ^^^^^^^^^^^ doesn't have a size known at compile-time
    |
    = help: the trait `Sized` is not implemented for `[u8]`
-   = note: required by `Box::<T>::into_boxed_slice`
+   = note: required by `Box::<T, A>::into_boxed_slice`
 
 error[E0277]: the size for values of type `[u8]` cannot be known at compilation time
-  --> $DIR/box-into-boxed-slice-fail.rs:7:13
+  --> $DIR/into-boxed-slice-fail.rs:7:13
    |
 LL |     let _ = Box::into_boxed_slice(boxed_slice);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
@@ -17,16 +17,16 @@ LL |     let _ = Box::into_boxed_slice(boxed_slice);
    = note: slice and array elements must have `Sized` type
 
 error[E0277]: the size for values of type `dyn Debug` cannot be known at compilation time
-  --> $DIR/box-into-boxed-slice-fail.rs:11:35
+  --> $DIR/into-boxed-slice-fail.rs:11:35
    |
 LL |     let _ = Box::into_boxed_slice(boxed_trait);
    |                                   ^^^^^^^^^^^ doesn't have a size known at compile-time
    |
    = help: the trait `Sized` is not implemented for `dyn Debug`
-   = note: required by `Box::<T>::into_boxed_slice`
+   = note: required by `Box::<T, A>::into_boxed_slice`
 
 error[E0277]: the size for values of type `dyn Debug` cannot be known at compilation time
-  --> $DIR/box-into-boxed-slice-fail.rs:11:13
+  --> $DIR/into-boxed-slice-fail.rs:11:13
    |
 LL |     let _ = Box::into_boxed_slice(boxed_trait);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
diff --git a/src/test/ui/box-into-boxed-slice.rs b/src/test/ui/box/into-boxed-slice.rs
index 61b3d915253..61b3d915253 100644
--- a/src/test/ui/box-into-boxed-slice.rs
+++ b/src/test/ui/box/into-boxed-slice.rs
diff --git a/src/test/ui/box/leak-alloc.rs b/src/test/ui/box/leak-alloc.rs
new file mode 100644
index 00000000000..2e73d6f1432
--- /dev/null
+++ b/src/test/ui/box/leak-alloc.rs
@@ -0,0 +1,29 @@
+#![feature(allocator_api)]
+
+use std::alloc::{AllocError, AllocRef, Layout, System};
+use std::ptr::NonNull;
+
+use std::boxed::Box;
+
+struct Allocator {}
+
+unsafe impl AllocRef for Allocator {
+    fn alloc(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
+        System.alloc(layout)
+    }
+
+    unsafe fn dealloc(&self, ptr: NonNull<u8>, layout: Layout) {
+        System.dealloc(ptr, layout)
+    }
+}
+
+fn use_value(_: u32) {}
+
+fn main() {
+    let alloc = Allocator {};
+    let boxed = Box::new_in(10, alloc.by_ref());
+    let theref = Box::leak(boxed);
+    drop(alloc);
+    //~^ ERROR cannot move out of `alloc` because it is borrowed
+    use_value(*theref)
+}
diff --git a/src/test/ui/box/leak-alloc.stderr b/src/test/ui/box/leak-alloc.stderr
new file mode 100644
index 00000000000..09beb181460
--- /dev/null
+++ b/src/test/ui/box/leak-alloc.stderr
@@ -0,0 +1,15 @@
+error[E0505]: cannot move out of `alloc` because it is borrowed
+  --> $DIR/leak-alloc.rs:26:10
+   |
+LL |     let boxed = Box::new_in(10, alloc.by_ref());
+   |                                 ----- borrow of `alloc` occurs here
+LL |     let theref = Box::leak(boxed);
+LL |     drop(alloc);
+   |          ^^^^^ move out of `alloc` occurs here
+LL |
+LL |     use_value(*theref)
+   |               ------- borrow later used here
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0505`.
diff --git a/src/test/ui/box-new.rs b/src/test/ui/box/new.rs
index be1a40cf779..be1a40cf779 100644
--- a/src/test/ui/box-new.rs
+++ b/src/test/ui/box/new.rs
diff --git a/src/test/ui/coherence/impl-foreign-for-fundamental[foreign].stderr b/src/test/ui/coherence/impl-foreign-for-fundamental[foreign].stderr
index 0959e155c57..20dc955ffe4 100644
--- a/src/test/ui/coherence/impl-foreign-for-fundamental[foreign].stderr
+++ b/src/test/ui/coherence/impl-foreign-for-fundamental[foreign].stderr
@@ -2,9 +2,10 @@ error[E0117]: only traits defined in the current crate can be implemented for ar
   --> $DIR/impl-foreign-for-fundamental[foreign].rs:10:1
    |
 LL | impl Remote for Box<i32> {
-   | ^^^^^^^^^^^^^^^^--------
-   | |               |
-   | |               `i32` is not defined in the current crate
+   | ^^^^^------^^^^^--------
+   | |    |          |
+   | |    |          `i32` is not defined in the current crate
+   | |    `std::alloc::Global` is not defined in the current crate
    | impl doesn't use only types from inside the current crate
    |
    = note: define and implement a trait or new type instead
@@ -13,9 +14,10 @@ error[E0117]: only traits defined in the current crate can be implemented for ar
   --> $DIR/impl-foreign-for-fundamental[foreign].rs:14:1
    |
 LL | impl<T> Remote for Box<Rc<T>> {
-   | ^^^^^^^^^^^^^^^^^^^----------
-   | |                  |
-   | |                  `Rc` is not defined in the current crate
+   | ^^^^^^^^------^^^^^----------
+   | |       |          |
+   | |       |          `Rc` is not defined in the current crate
+   | |       `std::alloc::Global` is not defined in the current crate
    | impl doesn't use only types from inside the current crate
    |
    = note: define and implement a trait or new type instead
diff --git a/src/test/ui/coherence/impl-foreign[fundemental[foreign]]-for-foreign.stderr b/src/test/ui/coherence/impl-foreign[fundemental[foreign]]-for-foreign.stderr
index b4d559eb1f2..c1e2fdaf5e3 100644
--- a/src/test/ui/coherence/impl-foreign[fundemental[foreign]]-for-foreign.stderr
+++ b/src/test/ui/coherence/impl-foreign[fundemental[foreign]]-for-foreign.stderr
@@ -6,6 +6,7 @@ LL | impl Remote1<Box<String>> for i32 {
    | |    |                        |
    | |    |                        `i32` is not defined in the current crate
    | |    `String` is not defined in the current crate
+   | |    `std::alloc::Global` is not defined in the current crate
    | impl doesn't use only types from inside the current crate
    |
    = note: define and implement a trait or new type instead
@@ -18,6 +19,7 @@ LL | impl Remote1<Box<Rc<i32>>> for f64 {
    | |    |                         |
    | |    |                         `f64` is not defined in the current crate
    | |    `Rc` is not defined in the current crate
+   | |    `std::alloc::Global` is not defined in the current crate
    | impl doesn't use only types from inside the current crate
    |
    = note: define and implement a trait or new type instead
@@ -30,6 +32,7 @@ LL | impl<T> Remote1<Box<Rc<T>>> for f32 {
    | |       |                       |
    | |       |                       `f32` is not defined in the current crate
    | |       `Rc` is not defined in the current crate
+   | |       `std::alloc::Global` is not defined in the current crate
    | impl doesn't use only types from inside the current crate
    |
    = note: define and implement a trait or new type instead
diff --git a/src/test/ui/error-codes/e0119/conflict-with-std.stderr b/src/test/ui/error-codes/e0119/conflict-with-std.stderr
index 4b6b4430f32..9dc1a509cd0 100644
--- a/src/test/ui/error-codes/e0119/conflict-with-std.stderr
+++ b/src/test/ui/error-codes/e0119/conflict-with-std.stderr
@@ -5,8 +5,8 @@ LL | impl AsRef<Q> for Box<Q> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: conflicting implementation in crate `alloc`:
-           - impl<T> AsRef<T> for Box<T>
-             where T: ?Sized;
+           - impl<T, A> AsRef<T> for Box<T, A>
+             where A: AllocRef, T: ?Sized;
 
 error[E0119]: conflicting implementations of trait `std::convert::From<S>` for type `S`:
   --> $DIR/conflict-with-std.rs:12:1
diff --git a/src/test/ui/issues/issue-14092.rs b/src/test/ui/issues/issue-14092.rs
index 77da6badde9..3cfaa20a8b5 100644
--- a/src/test/ui/issues/issue-14092.rs
+++ b/src/test/ui/issues/issue-14092.rs
@@ -1,4 +1,4 @@
 fn fn1(0: Box) {}
-        //~^ ERROR wrong number of type arguments: expected 1, found 0 [E0107]
+        //~^ ERROR wrong number of type arguments: expected at least 1, found 0 [E0107]
 
 fn main() {}
diff --git a/src/test/ui/issues/issue-14092.stderr b/src/test/ui/issues/issue-14092.stderr
index 626830ece8c..b749c44780d 100644
--- a/src/test/ui/issues/issue-14092.stderr
+++ b/src/test/ui/issues/issue-14092.stderr
@@ -1,8 +1,8 @@
-error[E0107]: wrong number of type arguments: expected 1, found 0
+error[E0107]: wrong number of type arguments: expected at least 1, found 0
   --> $DIR/issue-14092.rs:1:11
    |
 LL | fn fn1(0: Box) {}
-   |           ^^^ expected 1 type argument
+   |           ^^^ expected at least 1 type argument
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-3601.stderr b/src/test/ui/issues/issue-3601.stderr
index adad480f92b..c873c20cca8 100644
--- a/src/test/ui/issues/issue-3601.stderr
+++ b/src/test/ui/issues/issue-3601.stderr
@@ -1,8 +1,8 @@
-error[E0004]: non-exhaustive patterns: `Box(_)` not covered
+error[E0004]: non-exhaustive patterns: `Box(_, _)` not covered
   --> $DIR/issue-3601.rs:30:44
    |
 LL |         box NodeKind::Element(ed) => match ed.kind {
-   |                                            ^^^^^^^ pattern `Box(_)` not covered
+   |                                            ^^^^^^^ pattern `Box(_, _)` not covered
    |
    = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms
    = note: the matched value is of type `Box<ElementKind>`
diff --git a/src/test/ui/issues/issue-41974.stderr b/src/test/ui/issues/issue-41974.stderr
index a092c94b9d5..cc4b3707dd6 100644
--- a/src/test/ui/issues/issue-41974.stderr
+++ b/src/test/ui/issues/issue-41974.stderr
@@ -1,13 +1,13 @@
-error[E0119]: conflicting implementations of trait `std::ops::Drop` for type `std::boxed::Box<_>`:
+error[E0119]: conflicting implementations of trait `std::ops::Drop` for type `std::boxed::Box<_, _>`:
   --> $DIR/issue-41974.rs:7:1
    |
 LL | impl<T> Drop for T where T: A {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: conflicting implementation in crate `alloc`:
-           - impl<T> Drop for Box<T>
-             where T: ?Sized;
-   = note: downstream crates may implement trait `A` for type `std::boxed::Box<_>`
+           - impl<T, A> Drop for Box<T, A>
+             where A: AllocRef, T: ?Sized;
+   = note: downstream crates may implement trait `A` for type `std::boxed::Box<_, _>`
 
 error[E0120]: the `Drop` trait may only be implemented for structs, enums, and unions
   --> $DIR/issue-41974.rs:7:18
diff --git a/src/test/ui/privacy/privacy-ns1.rs b/src/test/ui/privacy/privacy-ns1.rs
index 614375e5e51..c7084bfd980 100644
--- a/src/test/ui/privacy/privacy-ns1.rs
+++ b/src/test/ui/privacy/privacy-ns1.rs
@@ -33,7 +33,7 @@ fn test_glob2() {
     use foo2::*;
 
     let _x: Box<Bar>;  //~ ERROR wrong number of const arguments: expected 0, found 1
-    //~^ ERROR wrong number of type arguments: expected 1, found 0
+    //~^ ERROR wrong number of type arguments: expected at least 1, found 0
 }
 
 // neither public
diff --git a/src/test/ui/privacy/privacy-ns1.stderr b/src/test/ui/privacy/privacy-ns1.stderr
index eda9d4c128d..ccbb5d5c90f 100644
--- a/src/test/ui/privacy/privacy-ns1.stderr
+++ b/src/test/ui/privacy/privacy-ns1.stderr
@@ -58,11 +58,11 @@ error[E0107]: wrong number of const arguments: expected 0, found 1
 LL |     let _x: Box<Bar>;
    |                 ^^^ unexpected const argument
 
-error[E0107]: wrong number of type arguments: expected 1, found 0
+error[E0107]: wrong number of type arguments: expected at least 1, found 0
   --> $DIR/privacy-ns1.rs:35:13
    |
 LL |     let _x: Box<Bar>;
-   |             ^^^^^^^^ expected 1 type argument
+   |             ^^^^^^^^ expected at least 1 type argument
 
 error: aborting due to 5 previous errors
 
diff --git a/src/test/ui/privacy/privacy-ns2.rs b/src/test/ui/privacy/privacy-ns2.rs
index 0546de873f3..b770c8f8f86 100644
--- a/src/test/ui/privacy/privacy-ns2.rs
+++ b/src/test/ui/privacy/privacy-ns2.rs
@@ -39,7 +39,7 @@ fn test_single2() {
     use foo2::Bar;
 
     let _x : Box<Bar>; //~ ERROR wrong number of const arguments: expected 0, found 1
-    //~^ ERROR wrong number of type arguments: expected 1, found 0
+    //~^ ERROR wrong number of type arguments: expected at least 1, found 0
     let _x : Bar(); //~ ERROR expected type, found function `Bar`
 }
 
@@ -47,7 +47,7 @@ fn test_list2() {
     use foo2::{Bar,Baz};
 
     let _x: Box<Bar>; //~ ERROR wrong number of const arguments: expected 0, found 1
-    //~^ ERROR wrong number of type arguments: expected 1, found 0
+    //~^ ERROR wrong number of type arguments: expected at least 1, found 0
 }
 
 // neither public
diff --git a/src/test/ui/privacy/privacy-ns2.stderr b/src/test/ui/privacy/privacy-ns2.stderr
index d7d9b835275..dbb269c0ba6 100644
--- a/src/test/ui/privacy/privacy-ns2.stderr
+++ b/src/test/ui/privacy/privacy-ns2.stderr
@@ -84,11 +84,11 @@ error[E0107]: wrong number of const arguments: expected 0, found 1
 LL |     let _x : Box<Bar>;
    |                  ^^^ unexpected const argument
 
-error[E0107]: wrong number of type arguments: expected 1, found 0
+error[E0107]: wrong number of type arguments: expected at least 1, found 0
   --> $DIR/privacy-ns2.rs:41:14
    |
 LL |     let _x : Box<Bar>;
-   |              ^^^^^^^^ expected 1 type argument
+   |              ^^^^^^^^ expected at least 1 type argument
 
 error[E0107]: wrong number of const arguments: expected 0, found 1
   --> $DIR/privacy-ns2.rs:49:17
@@ -96,11 +96,11 @@ error[E0107]: wrong number of const arguments: expected 0, found 1
 LL |     let _x: Box<Bar>;
    |                 ^^^ unexpected const argument
 
-error[E0107]: wrong number of type arguments: expected 1, found 0
+error[E0107]: wrong number of type arguments: expected at least 1, found 0
   --> $DIR/privacy-ns2.rs:49:13
    |
 LL |     let _x: Box<Bar>;
-   |             ^^^^^^^^ expected 1 type argument
+   |             ^^^^^^^^ expected at least 1 type argument
 
 error: aborting due to 10 previous errors
 
diff --git a/src/test/ui/unique-object-noncopyable.stderr b/src/test/ui/unique-object-noncopyable.stderr
index 423350cd936..2e23ddd9053 100644
--- a/src/test/ui/unique-object-noncopyable.stderr
+++ b/src/test/ui/unique-object-noncopyable.stderr
@@ -1,27 +1,30 @@
 error[E0599]: no method named `clone` found for struct `Box<dyn Foo>` in the current scope
   --> $DIR/unique-object-noncopyable.rs:24:16
    |
-LL | trait Foo {
-   | ---------
-   | |
-   | doesn't satisfy `dyn Foo: Clone`
-   | doesn't satisfy `dyn Foo: Sized`
+LL |   trait Foo {
+   |   ---------
+   |   |
+   |   doesn't satisfy `dyn Foo: Clone`
+   |   doesn't satisfy `dyn Foo: Sized`
 ...
-LL |     let _z = y.clone();
-   |                ^^^^^ method not found in `Box<dyn Foo>`
+LL |       let _z = y.clone();
+   |                  ^^^^^ method not found in `Box<dyn Foo>`
    | 
-  ::: $SRC_DIR/alloc/src/boxed.rs:LL:COL
+  ::: $SRC_DIR/core/src/clone.rs:LL:COL
    |
-LL | pub struct Box<T: ?Sized>(Unique<T>);
-   | ------------------------------------- doesn't satisfy `Box<dyn Foo>: Clone`
+LL |       fn clone(&self) -> Self;
+   |          -----
+   |          |
+   |          the method is available for `Arc<Box<dyn Foo>>` here
+   |          the method is available for `Rc<Box<dyn Foo>>` here
    | 
-  ::: $SRC_DIR/core/src/clone.rs:LL:COL
+  ::: $SRC_DIR/alloc/src/boxed.rs:LL:COL
    |
-LL |     fn clone(&self) -> Self;
-   |        -----
-   |        |
-   |        the method is available for `Arc<Box<dyn Foo>>` here
-   |        the method is available for `Rc<Box<dyn Foo>>` here
+LL | / pub struct Box<
+LL | |     T: ?Sized,
+LL | |     #[unstable(feature = "allocator_api", issue = "32838")] A: AllocRef = Global,
+LL | | >(Unique<T>, A);
+   | |________________- doesn't satisfy `Box<dyn Foo>: Clone`
    |
    = note: the method `clone` exists but the following trait bounds were not satisfied:
            `dyn Foo: Sized`
diff --git a/src/test/ui/unique-pinned-nocopy.stderr b/src/test/ui/unique-pinned-nocopy.stderr
index d39db225043..d533724a009 100644
--- a/src/test/ui/unique-pinned-nocopy.stderr
+++ b/src/test/ui/unique-pinned-nocopy.stderr
@@ -1,24 +1,27 @@
 error[E0599]: no method named `clone` found for struct `Box<R>` in the current scope
   --> $DIR/unique-pinned-nocopy.rs:12:16
    |
-LL | struct R {
-   | -------- doesn't satisfy `R: Clone`
+LL |   struct R {
+   |   -------- doesn't satisfy `R: Clone`
 ...
-LL |     let _j = i.clone();
-   |                ^^^^^ method not found in `Box<R>`
+LL |       let _j = i.clone();
+   |                  ^^^^^ method not found in `Box<R>`
    | 
-  ::: $SRC_DIR/alloc/src/boxed.rs:LL:COL
+  ::: $SRC_DIR/core/src/clone.rs:LL:COL
    |
-LL | pub struct Box<T: ?Sized>(Unique<T>);
-   | ------------------------------------- doesn't satisfy `Box<R>: Clone`
+LL |       fn clone(&self) -> Self;
+   |          -----
+   |          |
+   |          the method is available for `Arc<Box<R>>` here
+   |          the method is available for `Rc<Box<R>>` here
    | 
-  ::: $SRC_DIR/core/src/clone.rs:LL:COL
+  ::: $SRC_DIR/alloc/src/boxed.rs:LL:COL
    |
-LL |     fn clone(&self) -> Self;
-   |        -----
-   |        |
-   |        the method is available for `Arc<Box<R>>` here
-   |        the method is available for `Rc<Box<R>>` here
+LL | / pub struct Box<
+LL | |     T: ?Sized,
+LL | |     #[unstable(feature = "allocator_api", issue = "32838")] A: AllocRef = Global,
+LL | | >(Unique<T>, A);
+   | |________________- doesn't satisfy `Box<R>: Clone`
    |
    = note: the method `clone` exists but the following trait bounds were not satisfied:
            `R: Clone`