Instead of the previous unreliable hack, actually look for occurrences
of the solved metavariable. Block if there are any, and fail if there
are any under a constructor. I had expected this to hurt performance
quite a bit, but it seems it doesn't.
This was prompted by #304, which is now partly fixed, but there's still
a refinement to unification needed to fix it fully (and at least it
doesn't segfault due to the cycle now!)
Sorry for the less than informative title :). Lots going on here. It
started as an attempt to fix unification to deal with laziness coercions
in trickier places, but unearthed a couple of tricky and interconnected
issues that are hard to unpick into a single patch. So, this fixes a few
things:
- default hints should only be resolved on the current elaboration (e.g.
nested function definitions, not the outer definition which might not
yet be complete)
- delayed elaborators should be allowed to have nested delayed
elaborators, which means disambiguation is a little bit better
- we should delay elaborating arguments where the type isn't known yet,
because later arguments may resolve the type, and we can use this to
help with disambiguation/laziness coercions
- other bits and pieces arising
With the --yaffle flag, you get the old behaviour which is to invoke the
checker for the core theory (and all the tests are updated appropriately
for this).
