From 99f0b6d16f0e9ab6027379c31ce6c99dc1db5e9c Mon Sep 17 00:00:00 2001
From: Matt Kulukundis <kfm@google.com>
Date: Wed, 7 Feb 2024 16:02:47 -0800
Subject: Switch rank structs to be consistent with written guidance in
 go/ranked-overloads

PiperOrigin-RevId: 605125821
Change-Id: I2ee260eaf283acafd80abfd2b7419a0e9f597a78
---
 absl/container/internal/common_policy_traits.h | 19 ++++++++++---------
 absl/strings/cord.h                            |  2 +-
 absl/strings/internal/cord_internal.h          | 11 ++++++-----
 3 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/absl/container/internal/common_policy_traits.h b/absl/container/internal/common_policy_traits.h
index 77df4790..c521f612 100644
--- a/absl/container/internal/common_policy_traits.h
+++ b/absl/container/internal/common_policy_traits.h
@@ -64,7 +64,7 @@ struct common_policy_traits {
   //                UNINITIALIZED
   template <class Alloc>
   static void transfer(Alloc* alloc, slot_type* new_slot, slot_type* old_slot) {
-    transfer_impl(alloc, new_slot, old_slot, Rank0{});
+    transfer_impl(alloc, new_slot, old_slot, Rank2{});
   }
 
   // PRECONDITION: `slot` is INITIALIZED
@@ -83,7 +83,7 @@ struct common_policy_traits {
 
   static constexpr bool transfer_uses_memcpy() {
     return std::is_same<decltype(transfer_impl<std::allocator<char>>(
-                            nullptr, nullptr, nullptr, Rank0{})),
+                            nullptr, nullptr, nullptr, Rank2{})),
                         std::true_type>::value;
   }
 
@@ -95,18 +95,19 @@ struct common_policy_traits {
   }
 
  private:
-  // To rank the overloads below for overload resolution. Rank0 is preferred.
-  struct Rank2 {};
-  struct Rank1 : Rank2 {};
-  struct Rank0 : Rank1 {};
+  // Use go/ranked-overloads for dispatching.
+  struct Rank0 {};
+  struct Rank1 : Rank0 {};
+  struct Rank2 : Rank1 {};
 
   // Use auto -> decltype as an enabler.
   // P::transfer returns std::true_type if transfer uses memcpy (e.g. in
   // node_slot_policy).
   template <class Alloc, class P = Policy>
   static auto transfer_impl(Alloc* alloc, slot_type* new_slot,
-                            slot_type* old_slot, Rank0)
-      -> decltype(P::transfer(alloc, new_slot, old_slot)) {
+                            slot_type* old_slot,
+                            Rank2) -> decltype(P::transfer(alloc, new_slot,
+                                                           old_slot)) {
     return P::transfer(alloc, new_slot, old_slot);
   }
 #if defined(__cpp_lib_launder) && __cpp_lib_launder >= 201606
@@ -129,7 +130,7 @@ struct common_policy_traits {
 
   template <class Alloc>
   static void transfer_impl(Alloc* alloc, slot_type* new_slot,
-                            slot_type* old_slot, Rank2) {
+                            slot_type* old_slot, Rank0) {
     construct(alloc, new_slot, std::move(element(old_slot)));
     destroy(alloc, old_slot);
   }
diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index d2ba9673..2583aa8a 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h
@@ -1120,7 +1120,7 @@ Cord MakeCordFromExternal(absl::string_view data, Releaser&& releaser) {
   } else {
     using ReleaserType = absl::decay_t<Releaser>;
     cord_internal::InvokeReleaser(
-        cord_internal::Rank0{}, ReleaserType(std::forward<Releaser>(releaser)),
+        cord_internal::Rank1{}, ReleaserType(std::forward<Releaser>(releaser)),
         data);
   }
   return cord;
diff --git a/absl/strings/internal/cord_internal.h b/absl/strings/internal/cord_internal.h
index 549f9175..a52deea1 100644
--- a/absl/strings/internal/cord_internal.h
+++ b/absl/strings/internal/cord_internal.h
@@ -352,18 +352,19 @@ struct CordRepExternal : public CordRep {
   static void Delete(CordRep* rep);
 };
 
-struct Rank1 {};
-struct Rank0 : Rank1 {};
+// Use go/ranked-overloads for dispatching.
+struct Rank0 {};
+struct Rank1 : Rank0 {};
 
 template <typename Releaser, typename = ::absl::base_internal::invoke_result_t<
                                  Releaser, absl::string_view>>
-void InvokeReleaser(Rank0, Releaser&& releaser, absl::string_view data) {
+void InvokeReleaser(Rank1, Releaser&& releaser, absl::string_view data) {
   ::absl::base_internal::invoke(std::forward<Releaser>(releaser), data);
 }
 
 template <typename Releaser,
           typename = ::absl::base_internal::invoke_result_t<Releaser>>
-void InvokeReleaser(Rank1, Releaser&& releaser, absl::string_view) {
+void InvokeReleaser(Rank0, Releaser&& releaser, absl::string_view) {
   ::absl::base_internal::invoke(std::forward<Releaser>(releaser));
 }
 
@@ -381,7 +382,7 @@ struct CordRepExternalImpl
   }
 
   ~CordRepExternalImpl() {
-    InvokeReleaser(Rank0{}, std::move(this->template get<0>()),
+    InvokeReleaser(Rank1{}, std::move(this->template get<0>()),
                    absl::string_view(base, length));
   }
 
-- 
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