Language-wide flags for language <LANG> used when building for all configurations. These flags will be passed to all invocations of the compiler. This includes invocations that drive compiling and those that drive linking.

For each language, if this variable is not defined, it is initialized and stored in the cache using values from environment variables in combination with CMake's builtin defaults for the toolchain:

  • CMAKE_C_FLAGS: Initialized by the CFLAGS environment variable.

  • CMAKE_CXX_FLAGS: Initialized by the CXXFLAGS environment variable.

  • CMAKE_CUDA_FLAGS: Initialized by the CUDAFLAGS environment variable.

  • CMAKE_Fortran_FLAGS: Initialized by the FFLAGS environment variable.

  • CMAKE_CSharp_FLAGS: Initialized by the CSFLAGS environment variable.

  • CMAKE_HIP_FLAGS: Initialized by the HIPFLAGS environment variable.

  • CMAKE_ISPC_FLAGS: Initialized by the ISPCFLAGS environment variable.

  • CMAKE_OBJC_FLAGS: Initialized by the OBJCFLAGS environment variable.

  • CMAKE_OBJCXX_FLAGS: Initialized by the OBJCXXFLAGS environment variable.

This value is a command-line string fragment. Therefore, multiple options should be separated by spaces, and options with spaces should be quoted.

The flags in this variable will be passed before those in the per-configuration CMAKE_<LANG>_FLAGS_<CONFIG> variable. On invocations driving compiling, flags from both variables will be passed before flags added by commands such as add_compile_options() and target_compile_options(). On invocations driving linking, they will be passed before flags added by commands such as add_link_options() and target_link_options().