GNUInstallDirs doesn't set LIBDIR proplery when installing to /usr/local and CMAKE_LIBRARY_ARCHITECTURE is defined.
When using multiarch on a debian system, sometimes it's useful to install into /usr/local/lib/${CMAKE_LIBRARY_ARCHITECTURE}
. The current GNUInstallDirs.cmake
only matches CMAKE_INSTALL_PREFIX
being empty or /usr/
.
See attachment for a possible solution.
GNUInstallDirs_libdir.diff