Backport fix for flapack_sym_herm.pyf.src to mainatince/1.9.x

[thomasjpfan]

While debugging a segfault in scikit-learn's test suite on Python 3.11 and Linux, I found that 292b643 is required to prevent the segfault. For testing, I cherry-picked the commit onto mainatince/1.9.x, build SciPy's wheel with cibuildwheel, and it resolve the segfault issue in scikit-learn's test suite.

Can SciPy backport 292b643 to mainatince/1.9.X?

Edit: For reference: this CI test run illustrates the error from Python. I get this backtrace when I have debug symbols on.

[thomasjpfan]

For verification, I built SciPy 1.9.3 wheels with 292b643 cherry-picked, uploaded it to my own index and ran scikit-learn's test suite using my index. This resolves the segfault issue and all the tests pass!

[tylerjereddy]

@rgommers @ilayn what do you think? As far as I can tell I simply missed a ping in gh-16528 back in July. We've already got 8 merged backport candidates after labeling that one.. shall I aim for 1.9.3 soon? There's some manual artifact downloaing/unzipping and wheel renaming on maintenance/1.9.x for releases but the process is a fair bit faster than it used to be at least.

[rgommers]

Yes, a 1.9.3 seems like a good idea. I think it'd be useful to do a scan through commits on main that weren't backported and see if anything else important may be missing. Not everyone is in the habit of thinking about backports when merging PRs.

[ilayn]

My apologies @tylerjereddy I should have marked it as a candidate instead of a mere ping. The code change is harmless for us but clearly has certain implications for downstream so I'd say at your first convenience it would be nice to have this backported either 1.9.2 backport if there will be or 1.9.3 if not.

[ev-br]

@tylerjereddy am tentatively adding a backport-candidate label so that it does not fall through the cracks again :-).

[tylerjereddy]

@ev-br I think we're good now--I already included the fix in #17239 right? 1.9.3 is on the way soon-ish

[ev-br]

Sorry for the noise then

[rgommers]

1.9.3 was released with the backport in it, so let's close this. Thanks all.