Using compiler prefix command(s) with CMake (distcc, ccache)

Since CMake 3.4.0 there has been a CMAKE_<LANG>_COMPILER_LAUNCHER variable and corresponding target property <LANG>_COMPILER_LAUNCHER. So if your project is C-only you would do something like:

cmake -DCMAKE_C_COMPILER_LAUNCHER=ccache /path/to/source
CCACHE_PREFIX=distcc make -j`distcc -j`

If you have a C++ project, use -DCMAKE_CXX_COMPILER_LAUNCHER=ccache.

Or, make your CMakeLists.txt smart and use ccache automatically if it can be found:

#-----------------------------------------------------------------------------
# Enable ccache if not already enabled by symlink masquerading and if no other
# CMake compiler launchers are already defined
#-----------------------------------------------------------------------------
find_program(CCACHE_EXECUTABLE ccache)
mark_as_advanced(CCACHE_EXECUTABLE)
if(CCACHE_EXECUTABLE)
  foreach(LANG C CXX)
    if(NOT DEFINED CMAKE_${LANG}_COMPILER_LAUNCHER AND NOT CMAKE_${LANG}_COMPILER MATCHES ".*/ccache")
      message(STATUS "Enabling ccache for ${LANG}")
      set(CMAKE_${LANG}_COMPILER_LAUNCHER ${CCACHE_EXECUTABLE} CACHE STRING "")
    endif()
  endforeach()
endif()

Just as a hint: never use <LANG>_COMPILER_LAUNCHER to cross compile. If <LANG>_COMPILER_LAUNCHER is used together with distcc the absolute compiler path is sent to distcc and the host is not using the cross comping toolchain!

Instead you should use the old school method, just overwrite the compiler path:

export PATH=/usr/lib/distcc:$PATH

It took me hours to find out...