From Get docs
This is a CMake Environment Variable. Its initial value is taken from the calling process environment.
Will only be used by CMake on the first configuration to determine the default linker flags, after which the value for
LDFLAGS is stored in the cache as CMAKE_EXE_LINKER_FLAGS_INIT, CMAKE_SHARED_LINKER_FLAGS_INIT, and CMAKE_MODULE_LINKER_FLAGS_INIT. For any configuration run (including the first), the environment variable will be ignored if the equivalent
CMAKE_<TYPE>_LINKER_FLAGS_INIT variable is defined.
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