Update the Travis macOS image from xcode7 to xcode7.3

[ararslan]

On their blog, Travis CI mentioned that they're consolidating their catalog of available macOS images. (See here.) We're currently using xcode7, which is not on their list of images that will be available going forward, so this PR updates it to xcode7.3.

[ararslan]

Of course this couldn't just go smoothly... there seems now to be OpenBLAS issues. 😕

[ararslan]

@tkelman Would we have to clear the Travis dependency cache in order for this to work?

Research suggests that the differences between XCode 7 and 7.3 should be minimal and non-breaking, but in practice, who knows...

[ararslan]

Clearing the Travis cache seems not to have changed anything.

[ararslan]

I'm honestly stumped as to why this would be causing issues. Any ideas, @staticfloat?

[staticfloat]

This looks like libopenblas is missing some dependencies. Can you add some debugging lines to the install script that do things like otool -L /path/to/libopenblas.dylib so we can see what libraries the openblas is trying to pull in?

[ararslan]

Here's the output from otool:

/usr/local/opt/openblas-julia/lib/libopenblas.dylib:
	/usr/local/opt/openblas-julia/lib/libopenblasp-r0.2.19.dylib (compatibility version 0.0.0, current version 0.0.0)
	/usr/local/opt/gcc/lib/gcc/6/libgfortran.3.dylib (compatibility version 4.0.0, current version 4.0.0)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1226.10.1)
	/usr/local/opt/gcc/lib/gcc/6/libquadmath.0.dylib (compatibility version 1.0.0, current version 1.0.0)

I added a bit that checks whether the linked libraries exist and they appear to exist...

[tkelman]

Does the juliadeps/libgfortran homebrew bottle contain libquadmath in it? If not, should it?

[ararslan]

Based on the formula it should and based on the bottle contents it does.

[staticfloat]

Maybe we should ask the travis guys if we can login and inspect the state of a run of this branch. I'm stumped.

[tkelman]

I'm going to guess this is something wrong with the bottles for 10.11. We should try xcode6.4 or xcode8 to see if they work any better. We can request temporary ssh access by contacting Travis' support email, but it's best if someone who will know what they're looking for and how to debug it on macs does that. If routing builds to a 10.10 or 10.12 VM works for now, let's do that so we aren't held up on debugging what's wrong with the bottles (or build environment, possibly).

[ararslan]

👍 We should shoot for newer rather than older, so I'll try xcode8 in a bit.

[ararslan]

:/ same story with xcode8. I guess I'll try 6.4 now.

[staticfloat]

I'm going to guess this is something wrong with the bottles for 10.11

This is my thought too, but I just tested on a completely clean OSX 10.11 VM, and I can run julia from my Homebrew tap just fine, which seems to point to something else, or some kind of interaction between the build environment and my bottles.

[tkelman]

Can you run the exact combination of steps that the .travis.yml does?

[vtjnash]

The DLYD environment variables are no longer supported by SIP binaries such as make, so that variable isn't being forwarded anymore. (e.g. see https://forums.developer.apple.com/thread/9233)

[tkelman]

Good catch, and pretty annoying of apple. Would rearranging the command lines to pass them in a way other than export help?

[ararslan]

Superseded by #19475