New in version 3.4.

Default value for <LANG>_COMPILER_LAUNCHER target property. This variable is used to initialize the property on each target as it is created. This is done only when <LANG> is C, CXX, Fortran, ISPC, OBJC, OBJCXX, or CUDA.

This variable is initialized to the CMAKE_<LANG>_COMPILER_LAUNCHER environment variable if it is set.