cmake: substitute _PREFIX explicitly during build

[morxa]

Instead of setting _PREFIX to CMAKE_CURRENT_LIST_FILE, explicitly substitute _PREFIX with the value of CMAKE_INSTALL_PREFIX during the build process.

This avoids a bug where COLLADA_DOM_ROOT_DIR was set to '/' if the path contains '/lib', which results in COLLADA_DOM_INCLUDE_DIRS being '/include/collada-dom' instead of '/usr/include/collada-dom'.

[morxa]

Note: I'm not entirely sure what the line get_filename_component(_PREFIX "${_PREFIX}" PATH) is supposed to do. In my understanding, it will only set _PREFIX to its current value, as it is already a PATH. Also, if there is a case where _PREFIX should NOT be CMAKE_INSTALL_PREFIX, this won't work. Please check this before merging.

[morxa]

This was reported on the Red Hat Bugzilla #1057985

[rdiankov]

wow, seems like this has been pretty heavily discussed. the relative paths was just a good way of making the config script robust if the install dir changed, if we use CMAKE_INSTALL_PREFIX, we're shooting that out the door.

just curious, why not do the following?

set(COLLADA_DOM_ROOT_DIR "@CMAKE_INSTALL_PREFIX@")

[morxa]

I wasn't sure if anything else relied on an existing _PREFIX (although a fast grep didn't find anything), so I figured I'd leave it in.

Is it necessary to be able to move the installation without a rebuild? I guess that's exactly what caused the issue, and Orion's comment suggests that this is not really supported by cmake.

[rdiankov]

i guess it should be fine. can you make the commit so i can merge? thanks

[morxa]

done

[rdiankov]

thanks!

[morxa]

Thanks for merging!