MSVC has added some new flags. Although they're not supported, this adds parsing support for them so clang-cl doesn't treat them as filenames.
Except for /fsanitize=address which we do support. (clang-cl already exposes the -fsanitize= option, but this allows using the MSVC-spelling with a slash.)
Can we ask (or check) how this one is implemented? Does it inject a custom __asan_default_options that returns detect_stack_use_after_return=1 or is it more involved?