Fixing 2996

[biddisco]

fix #2996

[hkaiser]

LGTM, thanks!

[sithhell]

It turns out that you run into this runtime problem with this change if hwloc is disabled:

[11:53:22] <jbjnr> apparently not. terminate called after throwing an instance of 'std::length_error'
[11:53:22] <jbjnr>   what():  vector::reserve
[11:53:35] <jbjnr> but that has nothing to do with my changes.

This seems to be closely related to the resource partitioner requiring hwloc.

[biddisco]

• option 1 Fix it so it works without hwloc (probably can't be made completely RP safe, but should work with anything that doesn't have RP in user code), and leave next release with hwloc optional.
• option 2 move forward with making hwloc compulsory and get compulsory status into the next release

[hkaiser]

@biddisco either way is fine for me.

[biddisco]

If nobody is too concerned about dropping hwloc optional status, then I will move forward with making hwloc compulsory and cleaning the noop topology away and promoting hwloc_topology

[hkaiser]

If nobody is too concerned about dropping hwloc optional status, then I will move forward with making hwloc compulsory and cleaning the noop topology away and promoting hwloc_topology.

Ok, cool. Please don't make hwloc 2.0 compulsory, though.

[msimberg]

Should we close this if we go with #2977 instead? Especially as this PR only fixes compilation but still fails at runtime.

[hkaiser]

We can close this once #2977 has been fixed, yes.

[msimberg]

Closing because of #3133.