New in version 3.21.

This is a CMake Environment Variable. Its initial value is taken from the calling process environment.

Add default compilation flags to be used when compiling HIP files.

CMake uses this environment variable value, in combination with its own builtin default flags for the toolchain, to initialize and store the CMAKE_HIP_FLAGS cache entry. This occurs the first time a build tree is configured for language HIP. For any configuration run (including the first), the environment variable will be ignored if the CMAKE_HIP_FLAGS variable is already defined.