hpb: Move add_const_if_T_is_const to template_help.h and delete traits.h

PiperOrigin-RevId: 673906280

hpb/BUILD

@@ -63,8 +63,8 @@ cc_library(
     visibility = ["//visibility:public"],
     deps = [
         ":hpb",
-        ":traits",
         "//hpb/backend/upb:interop",
+        "//hpb/internal:template_help",
         "//upb:base",
         "//upb:mem",
         "//upb:message",
@@ -74,15 +74,6 @@ cc_library(
     ],
 )
 
-# Internally used type traits.
-cc_library(
-    name = "traits",
-    hdrs = [
-        "traits.h",
-    ],
-    copts = UPB_DEFAULT_CPPOPTS,
-)
-
 # Common support code for C++ generated code.
 cc_library(
     name = "generated_hpb_support",

hpb/internal/BUILD

@@ -15,6 +15,7 @@ package(default_applicable_licenses = ["//:license"])
 cc_library(
     name = "template_help",
     hdrs = ["template_help.h"],
+    copts = UPB_DEFAULT_CPPOPTS,
     visibility = ["//hpb:__subpackages__"],
     deps = [
         "//hpb:ptr",

hpb/internal/template_help.h

@@ -43,6 +43,10 @@ using EnableIfHpbClass = std::enable_if_t<
 template <typename T>
 using EnableIfMutableProto = std::enable_if_t<!std::is_const<T>::value>;
 
+template <typename T, typename T2>
+using add_const_if_T_is_const =
+    std::conditional_t<std::is_const_v<T>, const T2, T2>;
+
 }  // namespace internal
 }  // namespace hpb
 

hpb/repeated_field.h

@@ -16,9 +16,8 @@
 
 #include "absl/strings/string_view.h"
 #include "google/protobuf/hpb/backend/upb/interop.h"
-#include "google/protobuf/hpb/hpb.h"
+#include "google/protobuf/hpb/internal/template_help.h"
 #include "google/protobuf/hpb/repeated_field_iterator.h"
-#include "google/protobuf/hpb/traits.h"
 #include "upb/base/string_view.h"
 #include "upb/mem/arena.h"
 #include "upb/message/array.h"

hpb/traits.h

@@ -1,21 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2023 Google LLC.  All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-
-#ifndef PROTOBUF_HPB_TRAITS_H_
-#define PROTOBUF_HPB_TRAITS_H_
-
-#include <type_traits>
-
-namespace hpb::internal {
-
-template <typename T, typename T2>
-using add_const_if_T_is_const =
-    std::conditional_t<std::is_const_v<T>, const T2, T2>;
-
-}  // namespace hpb::internal
-
-#endif  // PROTOBUF_HPB_TRAITS_H_