utils: Relocate the std::filesystem::hash_value libc fix...

...and make the use of std::hash consistent.

This will make it easier to remove the fix once the libc
implementation we use catches up with the C++ standard.

1 files changed, 36 insertions, 0 deletions

diff --git a/src/utils/cpp/path_hash.hpp b/src/utils/cpp/path_hash.hpp
new file mode 100644
index 00000000..b990161c
--- /dev/null
+++ b/src/utils/cpp/path_hash.hpp
@@ -0,0 +1,36 @@
+// Copyright 2023 Huawei Cloud Computing Technology Co., Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef INCLUDED_SRC_UTILS_CPP_PATH_HASH_HPP
+#define INCLUDED_SRC_UTILS_CPP_PATH_HASH_HPP
+
+#include <filesystem>
+
+#if (defined(__GLIBCXX__) and _GLIBCXX_RELEASE < 12) or \
+    (defined(_LIBCPP_VERSION) and _LIBCPP_VERSION < 16000)
+// std::hash<std::filesystem::path> is missing for
+// - GNU's libstdc++ < 12
+// - LLVM's libcxx < 16 (see https://reviews.llvm.org/D125394)
+namespace std {
+template <>
+struct hash<std::filesystem::path> {
+    [[nodiscard]] auto operator()(
+        std::filesystem::path const& ct) const noexcept -> std::size_t {
+        return std::filesystem::hash_value(ct);
+    }
+};
+}  // namespace std
+#endif
+
+#endif  // INCLUDED_SRC_UTILS_CPP_PATH_HASH_HPP