If a project writes `include(GNUInstallDirs)` before `project()` then
`CMAKE_SYSTEM_NAME` may not be set and an incorrect `LIBDIR` may be
computed. Warn about this case.
FreeBSD ports commit r484628 (Install texinfo files (GNU info) into
${PREFIX}/share/info, 2018-11-10) changed the "info" destination
from "info" to "share/info". The commit included a patch to their
distribution of CMake to fix the `GNUInstallDirs` module too.
Apply a similar logic change to our upstream version of the module.
We already made a similar change for GNU/kFreeBSD in commit
v3.13.0-rc2~8^2 (GNUInstallDirs: Don't use BSD info and man paths on
GNU/kFreeBSD, 2018-10-21).
Fixes: #18585
Teach the module to handle SYSCONFDIR and LOCALSTATEDIR properly if
CMAKE_INSTALL_PREFIX is set to `/` or `/usr` -- i.e. as expected by GNU
Coding Standard (i.e. set SYSCONFDIR to `/etc` and `LOCALSTATEDIR` to
`/var`). Also if CMAKE_INSTALL_PREFIX is set to /opt/pkg, `SYSCONFDIR`
must be set to `/etc/opt/pkg` and `LOCALSTATEDIR` to `/var/opt/pkg`
according to FHS.
Add a RunCMake.GNUInstallDirs test with cases covering various install
prefixes. Hard-code the architecture information. Tolerate all
platform-specific LIBDIR values.
Currently the root prefix is not handled well, but verify the current
behavior in the test anyway. This can be addressed with a future
change.
Inspired-by: Alex Turbov <i.zaufi@gmail.com>
Brad King