I’m posting this sort-of on behalf of the poster of kinetic uses unstable eigen3 on Ubuntu 16.04 on ROS Answers, as I believe this might deserve some wider discussion and attention.
Summarising: according to the OP, Canonical is shipping an unstable version of Eigen3 with Ubuntu Xenial (16.04), which means that all of ROS Kinetic is also depending on that version. According to launchpad.net/ubuntu/+source/eigen3, Xenial ships eigen3/3.3~beta1-2.
The OP has included an MWE that should show what (one of) the issue(s) is. I haven’t tried this myself (yet).
Upstream bug report is here (posted: 2018-02-21), but it doesn’t seem to get much attention.
If this is indeed an actual issue, are there any channels we could use to get some more response out of Canonical about this?
PS: I didn’t really know where to put this, so figured General was as good as any other category.
From past experience, contacting the Ubuntu bug team via IRC is usually the best way to raise visibility of the issue.
It may be easier to convince Canonical to either patch the specific commit that fixes the issue or to bump to 3.3.4 (same minor version) than to downgrade to a different minor version. If there is an ABI break, it may help to give the full list of packages requiring a rebuild as Ubuntu doesnt rebuild downstream packages by default.
I hate to say it, but it’s not really ‘my issue’, and I’m not sure I’ll have the time to follow up with Canonical.
My reason for posting this on Discourse was to give some visibility to the ROS Answers post and to start a discussion around whether this is serious enough for ‘the ROS community’ to perhaps devote some resources to get this fixed.
Looking into the upstream ticket “unstable” is not exactly the right characterization. The debian package was imported from the latest available release and has “stably” been using that release since there have been no changes. And I don’t think that there are any changes expected.
However it has been identified that there is a bug in that release as it was a prerelease. However as debian is quite conservative particularly about maintaining stability they are very unlikely to switch to a newer or older release. Suggesting this in the ubuntu/debian bug tracker is not going to get much attention. However for a bug such as this if there’s a patch that can be applied without breaking the ABI they will likely consider applying that to the debian package.
We definitely do not want to diverge from what ubuntu/debian is packaging on a package as core as eigen. The best way to resolve this would be to submit a patch to the debian package that resolve the known/reproducible bug in the hopes that their review will determine that it’s likely to resolve more issues than it creates, for users expecting stability from the distribution.