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.

9 files changed, 54 insertions, 26 deletions

diff --git a/src/buildtool/build_engine/target_map/TARGETS b/src/buildtool/build_engine/target_map/TARGETS
index 92c55cbd..e2c76c8e 100644
--- a/src/buildtool/build_engine/target_map/TARGETS
+++ b/src/buildtool/build_engine/target_map/TARGETS
@@ -61,6 +61,7 @@
     , ["src/buildtool/logging", "logging"]
     , ["src/utils/cpp", "hash_combine"]
     , ["src/utils/cpp", "path"]
+    , ["src/utils/cpp", "path_hash"]
     , ["src/utils/cpp", "vector"]
     ]
   }
diff --git a/src/buildtool/build_engine/target_map/utils.cpp b/src/buildtool/build_engine/target_map/utils.cpp
index 24e0e8a7..050749de 100644
--- a/src/buildtool/build_engine/target_map/utils.cpp
+++ b/src/buildtool/build_engine/target_map/utils.cpp
@@ -20,6 +20,7 @@
 #include <vector>
 
 #include "src/utils/cpp/path.hpp"
+#include "src/utils/cpp/path_hash.hpp"
 
 auto BuildMaps::Target::Utils::obtainTargetByName(
     const SubExprEvaluator& eval,
@@ -111,7 +112,7 @@ auto BuildMaps::Target::Utils::tree_conflict(const ExpressionPtr& map)
     struct PathHash {
         auto operator()(std::filesystem::path const& p) const noexcept
             -> std::size_t {
-            return std::filesystem::hash_value(p);
+            return std::hash<std::filesystem::path>{}(p);
         }
     };
     std::unordered_set<std::filesystem::path, PathHash> blocked{};
diff --git a/src/other_tools/ops_maps/TARGETS b/src/other_tools/ops_maps/TARGETS
index c270978a..21a63306 100644
--- a/src/other_tools/ops_maps/TARGETS
+++ b/src/other_tools/ops_maps/TARGETS
@@ -7,6 +7,7 @@
     [ ["src/buildtool/multithreading", "async_map_consumer"]
     , ["src/other_tools/git_operations", "git_operations"]
     , ["src/utils/cpp", "hash_combine"]
+    , ["src/utils/cpp", "path_hash"]
     ]
   , "stage": ["src", "other_tools", "ops_maps"]
   }
@@ -20,6 +21,7 @@
     , ["src/other_tools/git_operations", "git_repo_remote"]
     , ["@", "fmt", "", "fmt"]
     , ["src/utils/cpp", "path"]
+    , ["src/utils/cpp", "path_hash"]
     ]
   , "stage": ["src", "other_tools", "ops_maps"]
   , "private-deps":
diff --git a/src/other_tools/ops_maps/critical_git_op_map.hpp b/src/other_tools/ops_maps/critical_git_op_map.hpp
index bb9b2765..58c2d3a1 100644
--- a/src/other_tools/ops_maps/critical_git_op_map.hpp
+++ b/src/other_tools/ops_maps/critical_git_op_map.hpp
@@ -22,6 +22,7 @@
 #include "src/buildtool/multithreading/async_map_consumer.hpp"
 #include "src/other_tools/git_operations/git_operations.hpp"
 #include "src/utils/cpp/hash_combine.hpp"
+#include "src/utils/cpp/path_hash.hpp"
 
 using GitOpKeyMap = std::unordered_map<
     GitOpType,
@@ -66,7 +67,7 @@ class CriticalGitOpGuard {
         // making sure only one thread at a time processes this section
         std::scoped_lock<std::mutex> const lock(critical_key_mutex_);
         auto target_path_key =
-            std::filesystem::hash_value(new_key.params.target_path);
+            std::hash<std::filesystem::path>{}(new_key.params.target_path);
         if (curr_critical_key_.contains(target_path_key)) {
             GitOpKey old_key =
                 curr_critical_key_[target_path_key];  // return stored key
@@ -89,11 +90,7 @@ struct hash<GitOpParams> {
     [[nodiscard]] auto operator()(GitOpParams const& ct) const noexcept
         -> std::size_t {
         size_t seed{};
-        // hash_value is used due to a bug in stdlibc++ which makes
-        // std::hash<std::filesystem::path>{}() fail with `temporary of type
-        // '__hash_enum<std::filesystem::__cxx11::path>' has private destructor`
-        hash_combine<size_t>(&seed,
-                             std::filesystem::hash_value(ct.target_path));
+        hash_combine<std::filesystem::path>(&seed, ct.target_path);
         hash_combine<std::string>(&seed, ct.git_hash);
         hash_combine<std::string>(&seed, ct.branch);
         return seed;
diff --git a/src/other_tools/ops_maps/import_to_git_map.hpp b/src/other_tools/ops_maps/import_to_git_map.hpp
index ee0b3c8f..487bae7c 100644
--- a/src/other_tools/ops_maps/import_to_git_map.hpp
+++ b/src/other_tools/ops_maps/import_to_git_map.hpp
@@ -21,6 +21,7 @@
 #include "src/other_tools/git_operations/git_repo_remote.hpp"
 #include "src/other_tools/ops_maps/critical_git_op_map.hpp"
 #include "src/utils/cpp/path.hpp"
+#include "src/utils/cpp/path_hash.hpp"
 
 struct CommitInfo {
     std::filesystem::path target_path{}; /*key*/
@@ -45,9 +46,7 @@ template <>
 struct hash<CommitInfo> {
     [[nodiscard]] auto operator()(CommitInfo const& ct) const noexcept
         -> std::size_t {
-        // hash_value is used due to a bug in stdlibc++
-        // (see critical_git_op_map.hpp)
-        return std::filesystem::hash_value(ct.target_path);
+        return std::hash<std::filesystem::path>{}(ct.target_path);
     }
 };
 }  // namespace std
diff --git a/src/other_tools/root_maps/TARGETS b/src/other_tools/root_maps/TARGETS
index d2bb01a3..e4bc6990 100644
--- a/src/other_tools/root_maps/TARGETS
+++ b/src/other_tools/root_maps/TARGETS
@@ -49,6 +49,7 @@
   , "deps":
     [ ["src/other_tools/ops_maps", "import_to_git_map"]
     , ["@", "json", "", "json"]
+    , ["src/utils/cpp", "path_hash"]
     ]
   , "stage": ["src", "other_tools", "root_maps"]
   , "private-deps":
diff --git a/src/other_tools/root_maps/fpath_git_map.hpp b/src/other_tools/root_maps/fpath_git_map.hpp
index 7f772eff..9b209163 100644
--- a/src/other_tools/root_maps/fpath_git_map.hpp
+++ b/src/other_tools/root_maps/fpath_git_map.hpp
@@ -17,26 +17,11 @@
 
 #include "nlohmann/json.hpp"
 #include "src/other_tools/ops_maps/import_to_git_map.hpp"
+#include "src/utils/cpp/path_hash.hpp"
 
 /// \brief Maps the path to a repo on the file system to its Git tree WS root.
 using FilePathGitMap = AsyncMapConsumer<std::filesystem::path, nlohmann::json>;
 
-#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
-
 [[nodiscard]] auto CreateFilePathGitMap(
     std::optional<std::string> const& current_subcmd,
     gsl::not_null<CriticalGitOpMap*> const& critical_git_op_map,
diff --git a/src/utils/cpp/TARGETS b/src/utils/cpp/TARGETS
index fffb2e7b..73c5e462 100644
--- a/src/utils/cpp/TARGETS
+++ b/src/utils/cpp/TARGETS
@@ -77,4 +77,10 @@
   , "deps": [["@", "gsl", "", "gsl"]]
   , "stage": ["src", "utils", "cpp"]
   }
+, "path_hash":
+  { "type": ["@", "rules", "CC", "library"]
+  , "name": ["path_hash"]
+  , "hdrs": ["path_hash.hpp"]
+  , "stage": ["src", "utils", "cpp"]
+  }
 }
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