On 6 Nov 2018, at 08:27, Matthew Knepley <knepley@gmail.com> wrote:

sidx_api.cc:45:8: error: thread-local storage is unsupported for the current target

static __thread struct


Hmm. The internet suggests that various Xcode versions removed (and then later reinstated) thread local storage in apple's clang. Eg here: https://stackoverflow.com/questions/28094794/why-does-apple-clang-disallow-c11-thread-local-when-official-clang-supports/29929949#29929949

Seems like Xcode 8 and newer do support it. But you have a very old Xcode?

Lawrence