Narrowed down: Triggers an internal compiler error from cargo 1.68.0-nightly (f6e737b1e 2022-12-02). WIP: probably NOT compilable.

peter-lyons-kehl · peter-lyons-kehl · commit c09445813bc1 · 2022-12-11T20:20:06.000-08:00
diff --git a/library/alloc/src/collections/vec_deque/mod.rs b/library/alloc/src/collections/vec_deque/mod.rs
@@ -97,6 +97,7 @@ mod tests;
 pub struct VecDeque<
     T,
     #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
+    const COOP_PREFERRED: bool = true
 >
 where [(); alloc::co_alloc_metadata_num_slots::<A>()]:
 {
@@ -107,7 +108,7 @@ where [(); alloc::co_alloc_metadata_num_slots::<A>()]:
     // if `len == 0`, the exact value of `head` is unimportant.
     // if `T` is zero-Sized, then `self.len <= usize::MAX`, otherwise `self.len <= isize::MAX as usize`.
     len: usize,
-    buf: RawVec<T, A>,
+    buf: RawVec<T, A, COOP_PREFERRED>,
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]

Original file line number	Diff line number	Diff line change
`@@ -97,6 +97,7 @@ mod tests;`
`97`	`97`	`pub struct VecDeque<`
`98`	`98`	`T,`
`99`	`99`	`#[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,`
	`100`	`+ const COOP_PREFERRED: bool = true`
`100`	`101`	`>`
`101`	`102`	`where [(); alloc::co_alloc_metadata_num_slots::<A>()]:`
`102`	`103`	`{`
`@@ -107,7 +108,7 @@ where [(); alloc::co_alloc_metadata_num_slots::<A>()]:`
`107`	`108`	// if `len == 0`, the exact value of `head` is unimportant.
`108`	`109`	// if `T` is zero-Sized, then `self.len <= usize::MAX`, otherwise `self.len <= isize::MAX as usize`.
`109`	`110`	`len: usize,`
`110`		`- buf: RawVec<T, A>,`
	`111`	`+ buf: RawVec<T, A, COOP_PREFERRED>,`
`111`	`112`	`}`
`112`	`113`
`113`	`114`	`#[stable(feature = "rust1", since = "1.0.0")]`