Function unwindCallback

Fleece/Support/Backtrace.cc:58–69

    };

    static _Unwind_Reason_Code unwindCallback(struct _Unwind_Context* context, void* arg) {
        BacktraceState* state = static_cast<BacktraceState*>(arg);
        uintptr_t pc = _Unwind_GetIP(context);
        if (pc) {
            if (state->current == state->end) {
                return _URC_END_OF_STACK;
            } else {
                *state->current++ = reinterpret_cast<void*>(pc);
            }
        }
        return _URC_NO_REASON;
    }

    static int backtrace(void** buffer, size_t max) {
        BacktraceState state = {buffer, buffer + max};