STINNER Victor <report@bugs.python.org> wrote:
> My final commit includes an addition to What's New in Python 3.5 doc,
> including a notice in the porting section. It is not enough?

I'm not sure: The usual case with ABI changes is that extensions may segfault
if they are *not* recompiled [1].  In that case documenting it in What's New is
standard procedure.

Here the extension *is* recompiled and still segfaults.

> Even if the API is public, the PyMemAllocator thing is low level. It's not
> part of the stable ABI. Except failmalloc, I don't know any user. I don't
> expect a lot of complain and it's easy to port the code.

Perhaps it's worth asking on python-dev. Nathaniel's suggestion isn't bad
either (e.g. name it PyMemAllocatorEx).

[1] I was told on python-dev that many people in fact do not recompile.