Merge bitcoin/bitcoin#28076: util: Replace std::filesystem with util/fs.h

bbbbdb0cd57d75a06357d2811363d30a498f4499 ci: Add filesystem lint check (MarcoFalke)
fada2f91108a56cc5c447bd6b6fac411e4d5cdca refactor: Replace <filesystem> with <util/fs.h> (MarcoFalke)

Pull request description:

  Using `std::filesystem` is problematic:

  * There is a `fs` namespace wrapper for it. So having two ways to achieve the same is confusing.
  * Not using the `fs` wrapper is dangerous and buggy, because it disables known bugs by deleting problematic functions.

  Fix all issues by removing use of it and adding a linter to avoid using it again in the future.

ACKs for top commit:
  TheCharlatan:
    ACK  bbbbdb0cd57d75a06357d2811363d30a498f4499
  fanquake:
    ACK bbbbdb0cd57d75a06357d2811363d30a498f4499 🦀

Tree-SHA512: 0e2d49742b08eb2635e6fce41485277cb9c40fe20b81017c391d3472a43787db1278a236825714ca1e41c9d2f59913865cfb0c649e3c8ab1fb598c849f80c660

5 files changed, 7 insertions, 9 deletions

diff --git a/src/bitcoin-chainstate.cpp b/src/bitcoin-chainstate.cpp
index fc83a4ad3a..995b4781fc 100644
--- a/src/bitcoin-chainstate.cpp
+++ b/src/bitcoin-chainstate.cpp
@@ -26,13 +26,13 @@
 #include <scheduler.h>
 #include <script/sigcache.h>
 #include <util/chaintype.h>
+#include <util/fs.h>
 #include <util/thread.h>
 #include <validation.h>
 #include <validationinterface.h>
 
 #include <cassert>
 #include <cstdint>
-#include <filesystem>
 #include <functional>
 #include <iosfwd>
 #include <memory>
@@ -50,8 +50,8 @@ int main(int argc, char* argv[])
             << "           BREAK IN FUTURE VERSIONS. DO NOT USE ON YOUR ACTUAL DATADIR." << std::endl;
         return 1;
     }
-    std::filesystem::path abs_datadir = std::filesystem::absolute(argv[1]);
-    std::filesystem::create_directories(abs_datadir);
+    fs::path abs_datadir{fs::absolute(argv[1])};
+    fs::create_directories(abs_datadir);
 
 
     // SETUP: Context
diff --git a/src/common/args.cpp b/src/common/args.cpp
index cfaa4de72d..1f25d13bee 100644
--- a/src/common/args.cpp
+++ b/src/common/args.cpp
@@ -28,7 +28,6 @@
 #include <cstdint>
 #include <cstdlib>
 #include <cstring>
-#include <filesystem>
 #include <map>
 #include <optional>
 #include <stdexcept>
diff --git a/src/policy/fees.cpp b/src/policy/fees.cpp
index 9557594622..654c4cf0ce 100644
--- a/src/policy/fees.cpp
+++ b/src/policy/fees.cpp
@@ -1044,8 +1044,8 @@ void CBlockPolicyEstimator::FlushUnconfirmed()
 
 std::chrono::hours CBlockPolicyEstimator::GetFeeEstimatorFileAge()
 {
-    auto file_time = std::filesystem::last_write_time(m_estimation_filepath);
-    auto now = std::filesystem::file_time_type::clock::now();
+    auto file_time{fs::last_write_time(m_estimation_filepath)};
+    auto now{fs::file_time_type::clock::now()};
     return std::chrono::duration_cast<std::chrono::hours>(now - file_time);
 }
 
diff --git a/src/util/fs.h b/src/util/fs.h
index 8f79f6cba6..7e2803b6aa 100644
--- a/src/util/fs.h
+++ b/src/util/fs.h
@@ -184,6 +184,7 @@ static inline path PathFromString(const std::string& string)
  * already exists or is a symlink to an existing directory.
  * This is a temporary workaround for an issue in libstdc++ that has been fixed
  * upstream [PR101510].
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101510
  */
 static inline bool create_directories(const std::filesystem::path& p)
 {
diff --git a/src/util/fs_helpers.cpp b/src/util/fs_helpers.cpp
index 2a9eb3502e..8aa7493aa8 100644
--- a/src/util/fs_helpers.cpp
+++ b/src/util/fs_helpers.cpp
@@ -11,13 +11,11 @@
 
 #include <logging.h>
 #include <sync.h>
-#include <tinyformat.h>
 #include <util/fs.h>
 #include <util/getuniquepath.h>
 #include <util/syserror.h>
 
 #include <cerrno>
-#include <filesystem>
 #include <fstream>
 #include <map>
 #include <memory>
@@ -263,7 +261,7 @@ bool RenameOver(fs::path src, fs::path dest)
 {
 #ifdef __MINGW64__
     // This is a workaround for a bug in libstdc++ which
-    // implements std::filesystem::rename with _wrename function.
+    // implements fs::rename with _wrename function.
     // This bug has been fixed in upstream:
     //  - GCC 10.3: 8dd1c1085587c9f8a21bb5e588dfe1e8cdbba79e
     //  - GCC 11.1: 1dfd95f0a0ca1d9e6cbc00e6cbfd1fa20a98f312