Add common_policy_traits - a subset of hash_policy_traits that can be shared between raw_hash_set and btree.

Also remove the transfer implementations from btree_set.h and flat_hash_set.h, which are equivalent to the default implementations.

Motivation: this will simplify upcoming changes related to trivial relocation.
PiperOrigin-RevId: 477493403
Change-Id: I75babef4c93dec3a8105f86c58af54199bb1ec9c

1 files changed, 0 insertions, 6 deletions

diff --git a/absl/container/btree_set.h b/absl/container/btree_set.h
index 695b09f5..e823a2a0 100644
--- a/absl/container/btree_set.h
+++ b/absl/container/btree_set.h
@@ -760,12 +760,6 @@ struct set_slot_policy {
   static void destroy(Alloc *alloc, slot_type *slot) {
     absl::allocator_traits<Alloc>::destroy(*alloc, slot);
   }
-
-  template <typename Alloc>
-  static void transfer(Alloc *alloc, slot_type *new_slot, slot_type *old_slot) {
-    construct(alloc, new_slot, old_slot);
-    destroy(alloc, old_slot);
-  }
 };
 
 // A parameters structure for holding the type parameters for a btree_set.