Rollback providing AbslHashValue for std::filesystem::path in C++17

'path' is unavailable: introduced in iOS 13.0

PiperOrigin-RevId: 583036562
Change-Id: I5aea530d03c3317896c3c15bcf7cb5f9d8bc466a

absl/hash/hash_test.cc

@@ -48,10 +48,6 @@
 #include "absl/types/optional.h"
 #include "absl/types/optional.h"
 #include "absl/types/variant.h"
 #include "absl/types/variant.h"
 
 
-#if ABSL_INTERNAL_CPLUSPLUS_LANG >= 201703L
-#include <filesystem>  // NOLINT
-#endif
-
 #ifdef ABSL_HAVE_STD_STRING_VIEW
 #ifdef ABSL_HAVE_STD_STRING_VIEW
 #include <string_view>
 #include <string_view>
 #endif
 #endif
@@ -484,43 +480,6 @@ TEST(HashValueTest, U32StringView) {
 #endif
 #endif
 }
 }
 
 
-TEST(HashValueTest, StdFilesystemPath) {
-#if ABSL_INTERNAL_CPLUSPLUS_LANG < 201703L
-  GTEST_SKIP() << "std::filesystem::path requires C++17";
-#else
-  EXPECT_TRUE((is_hashable<std::filesystem::path>::value));
-
-  // clang-format off
-  const auto kTestCases = std::make_tuple(
-      std::filesystem::path(),
-      std::filesystem::path("/"),
-#ifndef __GLIBCXX__
-      // libstdc++ has a known issue normalizing "//".
-      // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106452
-      std::filesystem::path("//"),
-#endif
-      std::filesystem::path("/a/b"),
-      std::filesystem::path("/a//b"),
-      std::filesystem::path("a/b"),
-      std::filesystem::path("a/b/"),
-      std::filesystem::path("a//b"),
-      std::filesystem::path("a//b/"),
-      std::filesystem::path("c:/"),
-      std::filesystem::path("c:\\"),
-      std::filesystem::path("c:\\/"),
-      std::filesystem::path("c:\\//"),
-      std::filesystem::path("c://"),
-      std::filesystem::path("c://\\"),
-      std::filesystem::path("/e/p"),
-      std::filesystem::path("/s/../e/p"),
-      std::filesystem::path("e/p"),
-      std::filesystem::path("s/../e/p"));
-  // clang-format on
-
-  EXPECT_TRUE(absl::VerifyTypeImplementsAbslHashCorrectly(kTestCases));
-#endif
-}
-
 TEST(HashValueTest, StdArray) {
 TEST(HashValueTest, StdArray) {
   EXPECT_TRUE((is_hashable<std::array<int, 3>>::value));
   EXPECT_TRUE((is_hashable<std::array<int, 3>>::value));
 
 

absl/hash/internal/hash.h

@@ -56,10 +56,6 @@
 #include "absl/types/variant.h"
 #include "absl/types/variant.h"
 #include "absl/utility/utility.h"
 #include "absl/utility/utility.h"
 
 
-#if ABSL_INTERNAL_CPLUSPLUS_LANG >= 201703L
-#include <filesystem>  // NOLINT
-#endif
-
 #ifdef ABSL_HAVE_STD_STRING_VIEW
 #ifdef ABSL_HAVE_STD_STRING_VIEW
 #include <string_view>
 #include <string_view>
 #endif
 #endif
@@ -582,24 +578,6 @@ H AbslHashValue(H hash_state, std::basic_string_view<Char> str) {
 
 
 #endif  // ABSL_HAVE_STD_STRING_VIEW
 #endif  // ABSL_HAVE_STD_STRING_VIEW
 
 
-#if defined(__cpp_lib_filesystem) && __cpp_lib_filesystem >= 201703L
-
-// Support std::filesystem::path. The SFINAE is required because some string
-// types are implicitly convertible to std::filesystem::path.
-template <typename Path, typename H,
-          typename = absl::enable_if_t<
-              std::is_same_v<Path, std::filesystem::path>>>
-H AbslHashValue(H hash_state, const Path& path) {
-  // This is implemented by deferring to the standard library to compute the
-  // hash.  The standard library requires that for two paths, `p1 == p2`, then
-  // `hash_value(p1) == hash_value(p2)`. `AbslHashValue` has the same
-  // requirement. Since `operator==` does platform specific matching, deferring
-  // to the standard library is the simplest approach.
-  return H::combine(std::move(hash_state), std::filesystem::hash_value(path));
-}
-
-#endif  // defined(__cpp_lib_filesystem) && __cpp_lib_filesystem >= 201703L
-
 // -----------------------------------------------------------------------------
 // -----------------------------------------------------------------------------
 // AbslHashValue for Sequence Containers
 // AbslHashValue for Sequence Containers
 // -----------------------------------------------------------------------------
 // -----------------------------------------------------------------------------