The issue seems to be that the content of the foreign module is captured inside the MakeActions structure.

Oops! It's much simpler now too, not sure why I didn't do it this way in the first place. 👍

Huh, looks like the core library stuff is working now, it's one of the stackage builds that is failing.

@phadej Do you have any idea why this might happen? Maybe a build cache issue?

Looks like the sandbox is being cached between different builds, perhaps? Maybe we have to revert to no caching.

Yeah, I think this is because of the sandbox being cached between builds (which was intended). However, oddly, it's the Stackage LTS 2.22 build that's failing; surely, if the Stackage snapshot version is fixed, none of the dependencies' versions should change? I think we should start by clearing the Travis cache and rerunning the build. I think this can be done inside Travis' web UI.

Perhaps it also makes sense to add --force-reinstalls to the cabal install command?

My guess is that it's using the same cache between all of the different builds?