[cfe-users] Writing gcc-style dependency files with clang-cl

[Ted Mielczarek via cfe-users]

Hi there,

We're continuing to work on making Firefox build with clang-cl in more configurations, and one of my colleagues recently wondered[1] if we could generate Makefile dependencies with clang-cl the same way we would with clang or gcc (-MP -MD etc) instead of using the wrapper script[2] that we use with MSVC that parses the output of -showIncludes. Passing these options to clang-cl with `-Xclang` doesn't seem to work, however:

$ clang-cl -Fohello.obj -c hello.cpp -Xclang -MP -Xclang -MD -Xclang -MF -Xclang bar
error: unknown argument: '-MD'
error: unknown argument: '-MF'

Is this something we could make work?

Regards,
-Ted

1. https://bugzilla.mozilla.org/show_bug.cgi?id=1340588
2. https://dxr.mozilla.org/mozilla-central/source/python/mozbuild/mozbuild/action/cl.py