From 5bbc6fc6aa2360149550ab009962523129c886fe Mon Sep 17 00:00:00 2001
From: Mike Kruskal <mkruskal@google.com>
Date: Tue, 24 Jan 2023 18:25:12 -0800
Subject: [PATCH] Automated rollback of commit
 888810af33780e6cfc0c33b20ba97486515d1254.

PiperOrigin-RevId: 504428590
---
 src/google/protobuf/BUILD.bazel  |  1 -
 src/google/protobuf/map.h        | 31 ++++++++++++++++++-------------
 src/google/protobuf/map_test.inc |  4 +++-
 3 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/src/google/protobuf/BUILD.bazel b/src/google/protobuf/BUILD.bazel
index 79c31cdb7489..e2b97f3147ea 100644
--- a/src/google/protobuf/BUILD.bazel
+++ b/src/google/protobuf/BUILD.bazel
@@ -337,7 +337,6 @@ cc_library(
         "//src/google/protobuf/stubs:lite",
         "@com_google_absl//absl/container:btree",
         "@com_google_absl//absl/container:flat_hash_set",
-        "@com_google_absl//absl/hash",
         "@com_google_absl//absl/meta:type_traits",
         "@com_google_absl//absl/numeric:bits",
         "@com_google_absl//absl/strings:internal",
diff --git a/src/google/protobuf/map.h b/src/google/protobuf/map.h
index da61c2b5cd54..78ad72c4dd9f 100644
--- a/src/google/protobuf/map.h
+++ b/src/google/protobuf/map.h
@@ -46,15 +46,17 @@
 #include <type_traits>
 #include <utility>
 
+#if defined(__cpp_lib_string_view)
+#include <string_view>
+#endif  // defined(__cpp_lib_string_view)
+
 #if !defined(GOOGLE_PROTOBUF_NO_RDTSC) && defined(__APPLE__)
 #include <mach/mach_time.h>
 #endif
 
 #include "google/protobuf/stubs/common.h"
 #include "absl/container/btree_map.h"
-#include "absl/hash/hash.h"
 #include "absl/meta/type_traits.h"
-#include "absl/strings/string_view.h"
 #include "google/protobuf/arena.h"
 #include "google/protobuf/generated_enum_util.h"
 #include "google/protobuf/map_type_handler.h"
@@ -227,31 +229,33 @@ struct TransparentSupport {
   using key_arg = key_type;
 };
 
-// We add transparent support for std::string keys. We use
-// std::hash<absl::string_view> as it supports the input types we care about.
-// The lookup functions accept arbitrary `K`. This will include any key type
-// that is convertible to absl::string_view.
+#if defined(__cpp_lib_string_view)
+// If std::string_view is available, we add transparent support for std::string
+// keys. We use std::hash<std::string_view> as it supports the input types we
+// care about. The lookup functions accept arbitrary `K`. This will include any
+// key type that is convertible to std::string_view.
 template <>
 struct TransparentSupport<std::string> {
-  static absl::string_view ImplicitConvert(absl::string_view str) {
-    return str;
-  }
-  // If the element is not convertible to absl::string_view, try to convert to
+  static std::string_view ImplicitConvert(std::string_view str) { return str; }
+  // If the element is not convertible to std::string_view, try to convert to
   // std::string first.
   // The template makes this overload lose resolution when both have the same
   // rank otherwise.
   template <typename = void>
-  static absl::string_view ImplicitConvert(const std::string& str) {
+  static std::string_view ImplicitConvert(const std::string& str) {
     return str;
   }
 
-  struct hash : public absl::Hash<absl::string_view> {
+  struct hash : private std::hash<std::string_view> {
     using is_transparent = void;
 
     template <typename T>
     size_t operator()(const T& str) const {
-      return absl::Hash<absl::string_view>::operator()(ImplicitConvert(str));
+      return base()(ImplicitConvert(str));
     }
+
+   private:
+    const std::hash<std::string_view>& base() const { return *this; }
   };
   struct less {
     using is_transparent = void;
@@ -270,6 +274,7 @@ struct TransparentSupport<std::string> {
   template <typename K>
   using key_arg = K;
 };
+#endif  // defined(__cpp_lib_string_view)
 
 struct NodeBase {
   // Align the node to allow KeyNode to predict the location of the key.
diff --git a/src/google/protobuf/map_test.inc b/src/google/protobuf/map_test.inc
index 4c11ecb6f622..6d1a70cd2b88 100644
--- a/src/google/protobuf/map_test.inc
+++ b/src/google/protobuf/map_test.inc
@@ -1404,7 +1404,9 @@ void TestTransparent(const Key& key, const Key& miss_key) {
 TEST_F(MapImplTest, TransparentLookupForString) {
   TestTransparent("ABC", "LKJ");
   TestTransparent(std::string("ABC"), std::string("LKJ"));
-  TestTransparent(absl::string_view("ABC"), absl::string_view("LKJ"));
+#if defined(__cpp_lib_string_view)
+  TestTransparent(std::string_view("ABC"), std::string_view("LKJ"));
+#endif  // defined(__cpp_lib_string_view)
 
   // std::reference_wrapper
   std::string abc = "ABC", lkj = "LKJ";