there's a few instances in BUILD.gn that I saw recently where "is_win" is used to set up compiler warnings and compiler flags, assuming that the compiler will be MSVC, when in fact it could be clang.

I suspect a lot of the 'is_win' could be changed to 'is_vc' when they directly change compiler options.

example: https://cs.chromium.org/chromium/src/third_party/skia/gn/BUILD.gn?sq=package:chromium&dr=C&l=272 it would appear that on win/clang the extended clang warnings (starting on L301) are never enabled.

I wonder if we should go through BUILD files and make sure is_win is not assuming MSVC?