cmake/Help/variable/CMAKE_LANG_LIBRARY_ARCHITECTURE.rst

CMAKE_<LANG>_LIBRARY_ARCHITECTURE
---------------------------------

Target architecture library directory name detected for ``<LANG>``.

If the ``<LANG>`` compiler passes to the linker an architecture-specific
system library search directory such as ``<prefix>/lib/<arch>`` this
variable contains the ``<arch>`` name if/as detected by CMake.