CMake honors the environment variables CC and CXX upon detecting the C and C++ compiler to use:
$ export CC=/usr/bin/clang $ export CXX=/usr/bin/clang++ $ cmake .. -- The C compiler identification is Clang -- The CXX compiler identification is Clang The compiler specific flags can be overridden by putting them into a make override file and pointing the CMAKE_USER_MAKE_RULES_OVERRIDE variable to it. Create a file ~/ClangOverrides.txt with the following contents:
SET (CMAKE_C_FLAGS_INIT "-Wall -std=c11") SET (CMAKE_C_FLAGS_DEBUG_INIT "-g") SET (CMAKE_C_FLAGS_MINSIZEREL_INIT "-Os -DNDEBUG") SET (CMAKE_C_FLAGS_RELEASE_INIT "-O3 -DNDEBUG") SET (CMAKE_C_FLAGS_RELWITHDEBINFO_INIT "-O2 -g") SET (CMAKE_CXX_FLAGS_INIT "-Wall -std=c++17") SET (CMAKE_CXX_FLAGS_DEBUG_INIT "-g") SET (CMAKE_CXX_FLAGS_MINSIZEREL_INIT "-Os -DNDEBUG") SET (CMAKE_CXX_FLAGS_RELEASE_INIT "-O3 -DNDEBUG") SET (CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT "-O2 -g") The suffix _INIT*_INIT will make CMake initialize the corresponding *_FLAGS variable with the given value. Then invoke cmake in the following way:
$ cmake -DCMAKE_USER_MAKE_RULES_OVERRIDE=~/ClangOverrides.txt .. Finally to force the use of the LLVM binutils, set the internal variable _CMAKE_TOOLCHAIN_PREFIX. This variable is honored by the CMakeFindBinUtils module:
$ cmake -D_CMAKE_TOOLCHAIN_PREFIX=llvm- .. Setting _CMAKE_TOOLCHAIN_LOCATION is no longer necessary for CMake version 3.9 or newer.
Putting this all together you can write a shell wrapper which sets up the environment variables CC and CXX and then invokes cmake with the mentioned variable overrides.
Also see this CMake FAQ on make override files.
