[LLVMdev] clean CMake build failing (Mac OS X 10.8)

[Marshall Clow]

Over the weekend I upgraded my system to Mac OS X 10.8, and now a clean cmake build fails.

The error message:
> Building C object runtime/libprofile/CMakeFiles/profile_rt-static.dir/CommonProfiling.c.o
> cc1: error: unrecognized command line option "-Wcovered-switch-default"


The configuration:
> Mac OS X 10.8
> CMake 2.8.8
> LLVM tot
> Apple clang version 4.0 (tags/Apple/clang-421.0.57) (based on LLVM 3.1svn)


Running cmake to generate the make files gives the following output:
> -- The C compiler identification is GNU 4.2.1
> -- The CXX compiler identification is Clang 4.0.0
> 

Diagnosis:
cmake is passing "-Wcovered-switch-default" to the c compiler.
It also thinks that the c compiler should be gcc, rather than clang.
gcc does not support that switch, and fails.

Possible solutions:
* use clang to compile the C code  (note that /usr/bin/cc is clang on this system; why it's picking gcc, I don't know)
* Don't pass "-Wcovered-switch-default" to the C compiler.

-- Marshall

Marshall Clow     Idio Software   <mailto:mclow.lists at gmail.com>

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