When llvm-rc invokes clang for preprocessing, it uses a target
triple derived from the default target. The test verifies that
e.g. _WIN32 is defined when preprocessing.
If running clang with e.g. -target ppc64le-windows-msvc, that
particular arch/OS combination isn't hooked up, so _WIN32 doesn't
get defined in that configuration. Therefore, the preprocessing
test fails.
Instead make llvm-rc inspect the architecture of the default target.
If it's one of the known supported architectures, use it as such,
otherwise set a default one (x86_64). (Clang can run preprocessing
with an x86_64 target triple, even if the x86 backend isn't
enabled.)
Also remove superfluous llvm:: specifications on enums in llvm-rc.cpp.
Allow opting out from preprocessing with a command line argument.
Update tests to pass -no-preprocess to make it not try to use clang
(which isn't a build level dependency of llvm-rc), but add a test that
does preprocessing under clang/test/Preprocessor.
Update a few options to allow them both joined (as -DFOO) and separate
(-D BR), as rc.exe allows both forms of them.
With the verbose flag set, this prints the preprocessing command
used (which differs from what rc.exe does).
Tests under llvm/test/tools/llvm-rc only test constructing the
preprocessor commands, while tests under clang/test/Preprocessor test
actually running the preprocessor.
Differential Revision: https://reviews.llvm.org/D100755
Martin Storsjö