Root cause analysis:
- clang-cl on GitHub Actions Windows Server 2022 cannot find std::filesystem
- The compiler defaults to pre-C++17 compatibility, exposing only std::experimental::filesystem
- Build logs show: -std=c++23 (Unix-style flag) instead of /std:c++latest (MSVC-style flag)
Key insight: CMAKE_CXX_COMPILER_FRONTEND_VARIANT is needed to distinguish:
- "MSVC": clang-cl (Clang with MSVC command-line interface)
- "GNU": regular Clang on Windows
Solution:
1. Use CMAKE_CXX_COMPILER_FRONTEND_VARIANT to properly detect clang-cl
2. Add /std:c++latest flag specifically to yaze_util target (where filesystem is used)
3. Apply as PUBLIC compile option so it propagates to dependent targets
This targets the exact source of the problem - clang-cl needs MSVC-style /std:c++latest
flag to access modern MSVC STL features including std::filesystem.
Tested approach based on CMake 3.16+ feature CMAKE_CXX_COMPILER_FRONTEND_VARIANT.
Related commits: 19196ca87c, c2bb90a3f1, b556b155a5
Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
cbdc6670a1