The problem is this: in Resolve.isAccessible when checks if a module can
access types from other modules does:
currModule.visiblePackages.get(p.fullname) == p
But if "p" is from an unnamed module, then it may or may not be in the
visiblePackages (depending on whether Symtab.lookupPackage was called on
the given package in the context of currModule), as unnamed module
packages are computed lazily. So this check may fail incorrectly.
The proposal here is to add one more check for the dependency on the