[libcxx-commits] [libcxxabi] [libunwind][libc++][libc++abi] Add cross-compilation flags to tests (PR #67201)

[Alexander Richardson via libcxx-commits]

arichardson wrote:

> Debugging shows that the reason this is failing on the clang-cl bots is that the CMAKE_CXX_FLAGS_INIT are using the MSVC syntax but we pass --driver-mode=g++ explicitly:
> 
> ```
> lit: C:\ws\src\libcxx\utils\libcxx\test\format.py:55: note: Command ["'C:/Program Files/LLVM/bin/clang-cl.exe' -xc++ nul -Werror -fsyntax-only --driver-mode=g++   /DWIN32 /D_WINDOWS /EHsc -fms-runtime-lib=dll -nostdinc++ -I C:/ws/src/build/clang-cl-dll/include/c++/v1 -I C:/ws/src/build/clang-cl-dll/include/c++/v1 -I C:/ws/src/libcxx/test/support -D_CRT_SECURE_NO_WARNINGS -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_STDIO_ISO_WIDE_SPECIFIERS -DNOMINMAX  -std=c++03"] failed with code 1: clang-cl: error: no such file or directory: '/DWIN32'
> --
>   | clang-cl: error: no such file or directory: '/D_WINDOWS'
>   | clang-cl: error: no such file or directory: '/EHsc'
> ```

I am less convinced now that this is the right solution since the CMake flags refer to the library build rather than the testing configuration, so maybe an explicit test suite parameter as in https://github.com/llvm/llvm-project/pull/65517 is the cleaner solution?

https://github.com/llvm/llvm-project/pull/67201