Fix build with XCode 10

[iamed2]

See https://developer.apple.com/documentation/xcode_release_notes/xcode_10_release_notes?language=objc

Fixes #11

[Roger-luo]

I was wondering whether this breaks the build on other platforms?

(That was why I didn't open a PR for this)

[iamed2]

I don't know if it's right either but I need it and Keno said it seemed fine on Slack

[ararslan]

I was wondering whether this breaks the build on other platforms?

It shouldn't, since this repository is specific to macOS. On other platforms we use libunwind.

[ararslan]

Unless you mean other macOS/Xcode versions. It would likely be worthwhile to condition on the version being used, since this wasn't a problem until recently. You should be able to use Apple's C macros to get versions.

[iamed2]

XCode 8+ will support this solution for sure, so we could condition on that, but I'm not sure what the macros are to check those things

[ararslan]

I think this should do it.

#include <AvailabilityMacros.h>

#if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_12
// stuff using -stdlib=libstdc++
#else
// stuff using -lstdc++
#endif

[iamed2]

It doesn't actually depend on your version of macOS though, it depends on your version of the XCode command line tools, which aren't directly tied.

[ararslan]

Each version of Xcode CLT has a minimum and maximum macOS version it supports, so it seems roughly safe to condition on the macOS version if we set it recent enough, even though it isn't a perfect check.