# Is stdatomic.h optional or required? **URL:** \ **Category:** Core Development\ **Created:** [August 11, 2025, 9:25am UTC](https://discuss.python.org/t/is-stdatomic-h-optional-or-required/101952 "2025-08-11T09:25:32Z")\ **Posts on this page:** 1\ **Showing post:** 6
**Author:** ![Rosuav](https://sea2.discourse-cdn.com/flex002/user_avatar/discuss.python.org/rosuav/32/3429_2.png) [@Rosuav](https://discuss.python.org/u/Rosuav)\ **Post date:** [August 11, 2025, 8:17pm UTC](https://discuss.python.org/t/is-stdatomic-h-optional-or-required/101952/6 "2025-08-11T20:17:54Z")
> [@ngoldbaum](#): > > I suspect the person in the other thread is using a somewhat nonstandard compiler setup that isn’t covered by CPython’s CI, and is somehow not hitting the LLVM or GCC-specific fallbacks in the pyatomic header. Some more info about what compiler toolchain they’re using would be helpful, I think, unless I missed that detail somewhere. The best info we have so far is: > [@Code explanation for absence of stdatomic.h for python build](https://discuss.python.org/t/code-explanation-for-absence-of-stdatomic-h-for-python-build/101623/10): > > Regarding your first question, my platform is NonStop(Non-Standard but similar to IBM AIX). Our compilers support C11 standards. but “C11 standard” doesn’t mandate stdatomic, so it’s entirely possible that it’s not GCC _and_ doesn’t have stdatomic. I’ll ask, as I’m not sure the OP of that thread saw this thread. > [@ngoldbaum](#): > > CPython has required atomic support to build for a while now. It doesn’t require stdatomic support, and as explained elsewhere will fall back to platform-specific code, but will error out if it can’t find a platform-specific definition at build time. That sounds like the wording of the `configure` message should be adjusted, then; the build requires stdatomic now, as opposed to potentially requiring it in the future. --- _[View the full topic](https://discuss.python.org/t/is-stdatomic-h-optional-or-required/101952)._