CoAlloc: FIXME: back to min_specialization

Author: peter-lyons-kehl

library/alloc/src/collections/vec_deque/spec_from_iter.rs

@@ -56,6 +56,46 @@ where
     }
 }
 
+// Until we can use feature `specialization`:
+// TODO macro
+impl<T>
+    SpecFromIterCo<T, crate::vec::IntoIter<T, Global, 0>>
+    for VecDeque<T, Global, 0>
+{
+    #[inline]
+    fn spec_from_iter_co(iterator: crate::vec::IntoIter<T, Global, 0>) -> Self {
+        iterator.into_vecdeque()
+    }
+}
+impl<T>
+    SpecFromIterCo<T, crate::vec::IntoIter<T, Global, 1>>
+    for VecDeque<T, Global, 1>
+{
+    #[inline]
+    fn spec_from_iter_co(iterator: crate::vec::IntoIter<T, Global, 1>) -> Self {
+        iterator.into_vecdeque()
+    }
+}
+
+impl<T> SpecFromIterCo<T, IntoIter<T, Global, 0>>
+    for VecDeque<T, Global, 0>
+{
+    #[inline]
+    fn spec_from_iter_co(iterator: IntoIter<T, Global, 0>) -> Self {
+        iterator.into_vecdeque()
+    }
+}
+impl<T> SpecFromIterCo<T, IntoIter<T, Global, 1>>
+    for VecDeque<T, Global, 1>
+{
+    #[inline]
+    fn spec_from_iter_co(iterator: IntoIter<T, Global, 1>) -> Self {
+        iterator.into_vecdeque()
+    }
+}
+
+// WITH unstable feature `specialization`:
+/*
 #[allow(unused_braces)]
 impl<T, const CO_ALLOC_PREF: CoAllocPref>
     SpecFromIterCo<T, crate::vec::IntoIter<T, Global, CO_ALLOC_PREF>>
@@ -80,3 +120,4 @@ where
         iterator.into_vecdeque()
     }
 }
+*/

library/alloc/src/lib.rs

@@ -184,13 +184,8 @@
 #![feature(hashmap_internals)]
 #![feature(lang_items)]
 #![feature(global_co_alloc_default)]
-// When we used min_specialization instead of specialization, library/alloc/src/vec/mod.rs was failing with:
-// - cannot specialize on predicate `the constant `core::alloc::co_alloc_metadata_num_slots::<A>()` can be evaluated`
-// - cannot specialize on predicate `[(); _] well-formed`
-// - cannot specialize on predicate `the constant `core::alloc::co_alloc_metadata_num_slots::<A>()` can be evaluated`
-//#![feature(min_specialization)]
+#![feature(min_specialization)]
 #![feature(associated_type_defaults)]
-#![feature(specialization)]
 #![feature(negative_impls)]
 #![feature(never_type)]
 #![feature(rustc_allow_const_fn_unstable)]