Switching to CircleCI 2.0

[msimberg]

As prepared by @sithhell. This should have very high priority in order to get tests running on PRs.

[sithhell]

Thanks for pushing that!

One thing we have to be aware of is that now, the circle checks will be flagged as failing, since we have lots of failing tests overall. But I think this is a good thing as it detects failures in PRs more easily and hopefully forces us to fix out tests.

[sithhell]

The other thing is, there will only be a new docker image once all tests pass ;)

[hkaiser]

I have no objections to merging this, thanks.

[msimberg]

My remaining concern regarding this is that the header tests fail with "cannot allocate memory" and others. Should we disable them and try to get them running using pycicle or buildbot instead? We are not worse off disabling them as circleci 1 does not build them either now.

[hkaiser]

@msimberg the existing CircleCI tests do run the header tests and I wouldn't like to lose that.

[msimberg]

@hkaiser Sorry, you're right. In that case that we should try to keep them running on circleci.

[msimberg]

Putting this for reference here: CircleCI 1.0 will not be supported anymore after August 31st, 2018.

[msimberg]

I played around a bit more and changed the following:

• the header tests depend on the hpx target, so the header tests workflow steps now depend on the core step (the header tests were all rebuilding hpx from scratch)
• for some inexplicable reason ninja caused the problems with "cannot allocate memory" and make had no problems, so I've changed the generator to Unix Makefiles (if someone has ideas on what ninja could possibly be doing differently I'd love to hear it)
• build all parallel algorithms even if the partitioned vector tests fail

[msimberg]

Any remaining concerns over this one?

@NK-Nikunj have I understood #3124 correctly that building the hello world component doesn't require any extra build steps now, and is part of tests/unit/build? I don't want to clobber your changes and end up with not building the hello world component again.

The only thing which fails now is building the partitioned vector tests which will show up red until they're fixed, but that we can live with.

[NK-Nikunj]

@msimberg yes, you have understood perfectly. The hello world component builds with tests.unit.build.

[msimberg]

I'm going to go ahead with this as we'll need this eventually. We can adjust it later on if needed.