Update libosxunwind to v0.0.4

[ararslan]

Fixes #29912.

[ararslan]

It sure would be nice to have working macOS CI for this.

[iamed2]

Is there an open issue for the macOS CI or is this a new problem?

[ararslan]

It's relatively new, not introduced here, but I don't think there's an open issue for it. Not sure what the issue actually is. Looking at the raw Travis log, the build and all tests actually completed successfully.

[ararslan]

Looks like macOS CI is working again, and tests here are passing on it.

[StefanKarpinski]

Cool, any reason not to merge?

[ararslan]

Not as far as I'm concerned, just figured having another set of eyes on it before we bump a dependency version would be worthwhile. The changes in this most recent tag of libosxunwind are incredibly minimal though.

[StefanKarpinski]

This is causing build problems on macOS, specifically:

make[2]: Circular src/libuwind.cxx <- src/libuwind.cxx.o dependency dropped.
warning: include path for stdlibc++ headers not found; pass '-std=libc++' on the command
      line to use the libc++ standard library instead [-Wstdlibcxx-not-found]
src/libuwind.cxx:28:10: fatal error: 'new' file not found
#include <new>
         ^~~~~
1 warning and 1 error generated.
make[2]: *** [src/libuwind.cxx.o] Error 1
make[1]: *** [scratch/libosxunwind-0.0.4/build-compiled] Error 2
make: *** [julia-deps] Error 2

[staticfloat]

What version of MacOS and what version of Xcode do you have installed?

[StefanKarpinski]

10.14.1 and I have updated all the things.

[staticfloat]

Okay the problem here is that the Julia build system is shoe-horning -std=libc++ into CC, which fights with libosxunwind and ends up with compiler invocations like:

clang++ -std=libc++ -mmacosx-version-min=10.8 -m64 -I/Users/sabae/src/julia-master/deps/scratch/libosxunwind-0.0.4/src -I/Users/sabae/src/julia-master/deps/scratch/libosxunwind-0.0.4/include -DNDEBUG  -std=c++11 -stdlib=libstdc++ -Wall -O3 -ggdb3 -O0 -c src/libuwind.cxx -o src/libuwind.cxx.o
warning: include path for stdlibc++ headers not found; pass '-std=libc++' on the command line to use the libc++ standard library instead [-Wstdlibcxx-not-found]

Note the cavalcade of problems here: two (incompatible) standard libraries being requested, an incorrect clang error message (-std=libc++ is an error, you need to use -stdlib=libc++) and a build system that coldly enforces its will upon lesser projects.

The reason that CI didn't catch this is that Julia only enforces this on OSX 10.13+. The reason that Alex and I didn't catch this is that we built libosxunwind in isolation, which doesn't have the CC/CXX bludgeoning that Julia does. So you really needed to build this inside of Julia, on a recent mac to see the problem.

I think the proper way to fix this is to patch libosxunwind to not try adding those flags by itself if those flags are already present within the variables it has inherited from upstream. I'll create a patch to do this. For now let's revert this PR, then move to the newer release in a future PR.

[staticfloat]

PR to fix this in libosxunwind is here: JuliaLang/libosxunwind#14

[wsshin]

I ran into this problem while building Julia 0.7 on a new Mac as @staticfloat pointed out. Couldn't figure out how to solve it (because I had no problem building 0.7 on my previous Mac). After reading this thread I tried building master and it succeeded.

Is it possible to backport this fix to 0.7? I still prefer using 0.7 to get deprecation warnings.

[ViralBShah]

As of now, there are no new 0.7 releases planed.

[ararslan]

You should be able to use the official 0.7 binaries for Mac available at https://julialang.org/downloads.