[cxx-abi-dev] Adding __cxa_thread_atexit() to the C++ ABI?

[Matthew Dempsky]

On Tue, May 13, 2014 at 8:18 PM, Jason Merrill <jason at redhat.com> wrote:
> Well, GCC supports lots of platforms that don't also use glibc.

Sure, but what's wrong with saying those platforms won't have proper
C++11 support until they implement __cxa_thread_atexit()?  Just like
how GCC supports (or used to support) platforms that don't have
__cxa_atexit() by using atexit() instead, and those platforms just
wouldn't have fully correct behavior.

Or just don't enable thread_local if __cxa_thread_atexit() isn't
available.  On platforms that don't support ELF TLS segments, GCC
prints a "thread-local storage not supported for this target" error
message when you try to use __thread.

But anyway, we've been arguing this back-and-forth a bit now. :)  I'd
love to hear some input from others on the list.  (And if not, I'll
probably fallback to "undefined behavior" if just for the sake of
getting it in the ABI.)