CPACK_NSIS_INSTALL_ROOT needs backslashes
The NSIS installer doesn't accept forward slashes in the installation path, it disables the "Next" button for such paths.
set(CPACK_NSIS_INSTALL_ROOT "C:\\Program Files" CACHE PATH "..." FORCE)
replaces the backslashes so we have to use something like set(CPACK_VERBATIM_VARIABLES ON CACHE BOOL "..." FORCE) set(CPACK_NSIS_INSTALL_ROOT "C:\\Program Files" CACHE STRING "..." FORCE)
instead, but could the former be fixed so that the latter workaround isn't needed anymore, perhaps by correcting the path separators before forwarding them to NSIS ?