media/libvpx/vpx_config_x86-win32-vs12.h claims that HAVE_STDINT_H is 0 (i.e. Windows doesn't have <stdint.h>, but MSVC 2013 (our minimum version to build) most certainly does have <stdint.h>. This redefinition of HAVE_STDINT_H causes conflicts with the definition we have in mozilla-config.h, and is picked up as a warning by clang-cl.

Ralph - this should be easy to fix, I think.

The configure script is fairly aggressive about not using it on visual studio. I've opened a bug upstream about it: https://bugs.chromium.org/p/webm/issues/detail?id=1119

Nevermind, it's likely not related to HAVE_STDINT_H since that define is unused in libvpx. It is being removed: https://chromium-review.googlesource.com/319250 (unless you just mean redefinition because mozilla-config.h uses HAVE_STDINT_H, which this will fix)