Allow overriding of SuiteSparse static library search

[6e441f9c]

My system SuiteSparse is not in one of the standard directories. It would be nice to have a way to override the path; not sure which way is better from Makefile maintainability point of view.

[ViralBShah]

I think we should just provide a shell script to do so. There is too much magic in building SuiteSparse that causes grief.

[ViralBShah]

@staticfloat, @6e441f9c Would you be ok if we just provide a shell script for compiling SuiteSparse's .a files into the appropriate shared library? It's quite hairy to accommodate all cases in the Makefile.

[6e441f9c]

If it is easier to write a shell script - of course. Hopefully separating this logic in another file would make it simpler to manage.

[6e441f9c]

Sorry for missing the button.

[staticfloat]

Absolutely, this is a much better solution than what's in the makefile right now.

[ViralBShah]

@vtjnash does your SuiteSparse related Makefile reorganization address this?

[vtjnash]

Yes, the intent of contrib/repackage_system_suitesparse.make is to make this possible. Running it will copy the SuiteSparse*.a locally, build a shared object file from them, and place it in the local usr/lib path. That way it gets found first and is built to include the same functions as the usual Julia build. I didn't rewrite it as an explicit shell script, since I just pulled out what I originally put in the deps/Makefile (and each step in a Makefile is a sh script), and it made it convenient to pass environment variables on the command line. It is intended that this can be run before Julia's make, to prepare the environment. Setting the environment variable LDFLAGS=-L/path/to/ss/lib is all that is needed to get it to find your system's SuiteSparse libraries.

There is a second possibilities here, which when an object library is not on the standard path (since julia looks for an object library containing the SuiteSparse functions at startup). You can set the environment variable LD_LIBRARY_PATH=/path/to/lib, but this is not ideal. I haven't really addressed this scenario yet (I could just put symlinks in usr/lib), but some patch for it is probably needed before I can put Julia on MacPorts, so it'll have to be done eventually.