Compile fail on macOS Catalina 10.15.6 - no namespace std::filesystem

[thefrostysnowman]

After following the Mac build steps, make is failing with the following:

.../waifu2x-converter-cpp/src/modelHandler_OpenCL.cpp:54:16: error: no namespace named 'filesystem' in namespace 'std'; did you mean std::__fs::filesystem'?
namespace fs = std::filesystem;
               ^~~~~~~~~~~~~~~
               std::__fs::filesystem
/usr/local/opt/llvm/bin/../include/c++/v1/filesystem:259:1: note: namespace 'std::__fs::filesystem' defined here
_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
^
/usr/local/opt/llvm/bin/../include/c++/v1/__config:790:58: note: expanded from macro '_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM'
  _LIBCPP_BEGIN_NAMESPACE_STD namespace __fs { namespace filesystem {
                                                         ^

By commenting out the offending line the build succeeded and Waifu2x works as expected. It appears the fs definition can be defined out for Mac?

Make specified this information about my machine:

-- Found git, set version to: v5.3.3 (master-e7de04d)
-- System is: Darwin (Apple)
CUDA_TOOLKIT_ROOT_DIR not found or specified
-- Could NOT find CUDA (missing: CUDA_TOOLKIT_ROOT_DIR CUDA_NVCC_EXECUTABLE CUDA_INCLUDE_DIRS CUDA_CUDART_LIBRARY) 
-- CUDA not found. disabled.
-- 
-- Config summary:
--  OpenCV: 4.4.0
--  OpenCL: 1.2
--  CUDA: Not found
--  Unicode: TRUE
--  Installing models to: /usr/local/share/waifu2x-converter-cpp
--  Not building test binaries
--  Building for: Unix Makefiles-x86_64

[EpLiar]

Try to modify this part: (It works on my Mac.)

54c54
< namespace fs = std::filesystem;
---
> namespace fs = std::__fs::filesystem;

[EpLiar]

Try to modify this part: (It works on my Mac.)

54c54
< namespace fs = std::filesystem;
---
> namespace fs = std::__fs::filesystem;

On https://github.com/DeadSix27/waifu2x-converter-cpp/blob/master/src/modelHandler_OpenCL.cpp

[thefrostysnowman]

Do you know if the std::__fs::filesystem namespace is available on all the platforms that currently successfully use std::filesystem? That's a clean solution if so.

I made a commit for my own use which skips the fs definition entirely if GENERATE_BINARY isn't defined since it isn't used unless GENERATE_BINARY is defined. Unfortunately I don't have any other computers to test my change on, so I can't validate whether this breaks another platform's compile. https://github.com/thefrostysnowman/waifu2x-converter-cpp/commit/96818ae2223d9d9abbf021d3a9d9f9cbd1d457dc

[EpLiar]

Do you know if the std::__fs::filesystem namespace is available on all the platforms that currently successfully use std::filesystem? That's a clean solution if so.

Or write a macro for macOS?

[YukihoAA]

Fixed by PR #255