Testing clang

[bhack]

This PR is trying to collect contribution of fixes to let Caffe tested on Ubuntu with clang untill travis-ci/travis-ci#2320 will let to test Caffe in Travis on OSX.

[bhack]

@shelhamer @jeffdonahue Please see the actual build status of clang on Travis

[jeffdonahue]

I'm not sure this tells me much -- I've never successfully built Caffe with clang on Linux. I see that the error is:

/usr/bin/ld: -f may not be used without -shared
clang: error: linker command failed with exit code 1 (use -v to see invocation)

But I don't know if that's due to some recent change in Caffe or if that was the error that clang has always given on Ubuntu without any further tweaking. Anyway, if you or anyone else can get the Travis build working with clang (on top of the existing gcc build) that would be very useful!

[shelhamer]

OS X CI is unlikely to be coming soon, but a dual GNU + clang build of Caffe would certainly be a step up and useful for the Travis CI. I have never compiled Caffe with clang on linux either, but welcome any hints on how to do so by those who might be more in the know about clang.

[longjon]

I have successfully built Caffe on Ubuntu with clang before. I don't remember the specific tweaks I made, and I don't have time right now to hunt them down, but maybe this fact will inspire someone to get it working for real!

[bhack]

If i add -shared flag compilation is ok but test binary got a segmentation fault. I think that is something related to the new factory.

[bhack]

Now clang with make and without Nvidia build and run fine. Do you have any feedback for 97.3 ?

[bhack]

@longjon @jeffdonahue It is still an hacky proof of concept. But what do you think of this build?

[bhack]

Seems that build fine. What we can do?

[bhack]

Seems that OSX it is enabled again on Travis. See travis-ci/travis-ci#216 (comment)

[shelhamer]

Closing since the dev branch is deprecated. Please send PRs to master.