Is it enough to only provide Boost_NO_SYSTEM_PATHS ?

It is somewhat weird to provide root directory for only one package. If this is something what needs to be done (aka, Boost_NO_SYSTEM_PATHS is not enough) we should specify root directories for all dependencies, to avoid similar issues with other packages in the future (this can happen in file like platform_common.cmake which will check whether precompiled lib is specified/exists and set ROOT for all libraries).

It is strange that it is necessary to set BOOST_ROOT. I just tested a few more combinations of the options.

Only setting Boost_NO_SYSTEM_PATHS results in the CMake build error I experienced previously, as explained in the first post here: https://devtalk.blender.org/t/building-on-linux-with-precompiled-libraries/11409/. Boost_NO_SYSTEM_PATHS and BOOST_ROOT also resulted in the error.

The combination Boost_NO_SYSTEM_PATHS and Boost_NO_BOOST_CMAKE had no CMake errors and it compiled, but it gave linking errors. Adding BOOST_ROOT cleared up the linker errors. Using BOOST_LIBRARYDIR in the place of BOOST_ROOT also allowed linking to complete.

So it seems that BOOST_ROOT is required to for linking, and Boost_NO_BOOST_CMAKE is required for CMake to finish. The other two options don't seem to have any impact on the output.

Wow, what a mess...

So here is a proposal then:

• Go ahead with this change
• Later on set all {FOO}_ROOT (try to re-use as much as possible on all platforms). This way we would also avoid file(GLOB LIB_SUBDIRS ${LIBDIR}/*) which is rather weak.

Brecht, Campbell, any strong opinion?

If linking error you're experiencing is due to zlib symbols you need to recompile blosc (if you're compiling libraries yourself), or svn up in the precompiled folder (if you use precompiled libraries).

If your linking error is something more weird and wonderful, please mail the list (I can miss messages on chat, and in ML more people might have clues). Don't forget to include details and linking error itself.