i spent several days trying to figure out how to compile hello world on osx in travis and as it turns out i was doing all this work to find the system include directories but i wasn't actually adding them to the compiler, but that's done now, so https://github.com/pantsbuild/pants/pull/5943 should be completed by later today. it has ballooned in size but i can and will cut it down and once it is merged we will be able to invoke compilers on all supported platforms without fear