Test: On `.compile.fail.cpp` in the libcxx test suite

[frederick-vs-ja]

It seems that CI for MSVC STL currently runs libcxx's .compile.fail.cpp and relies on the compilation failure. But libcxx probably has been desiring to change .compile.fail.cpp to .verify.cpp.

I think necessary changes are quite doable and have been preparing PRs. However, I'm not sure whether MSVC STL will be fine with the changes as they'll reduce coverage seemingly.

[cpplearner]

I think necessary changes are quite doable and have been preparing PRs. However, I'm not sure whether MSVC STL will be fine with the changes as they'll reduce coverage seemingly.

Do you mean, you are preparing PRs against libc++? I don't think anything needs to be done in microsoft/STL.

[frederick-vs-ja]

Do you mean, you are preparing PRs against libc++? I don't think anything needs to be done in microsoft/STL.

Yes. I just want maintainers of MSVC STL to confirm whether the changes will be fine.

[StephanTLavavej]

Could we enhance our GitHub test coverage to understand these .verify.cpp tests?

The negative test coverage generally hasn't found bugs/regressions for us, but it would be nice to avoid losing coverage.