Bug#1000780: eigen3 breaks pybind11 autopkgtest on ppc64el: inlining failed in call to ‘always_inline’

[Drew Parsons]

Source: pybind11
Version: 2.7.1-1
Followup-For: Bug #1000780

Sounds like some change was made in eigen3 3.4.0 which now breaks
pybind11 (pybind11 3.8.1 also fails the same way).

Not clear at this point if it's a regression in eigen3 that needs to
be fixed in eigen3, or an API change that pybind11 needs to patch.

But if it was an API problem then you'd expect the failure to show up
on other arches.  Arch-specific failure sometimes indicates wrong
assumptions are made about alignment.  "target specific option
mismatch" is certainly a clue, suggesting eigen has a target specific API.
I'll raise a bug against pybind11 upstream.