This is a debugging aid, not a general feature, hence the lack of testing or actual, correct semantics. Swift SVN r15886
Brings back the behavior removed in r15800 under a pair of flags (-module-print-submodules and -module-print-hidden) that control whether to print submodules, possibly including submodules that aren't explicitly visible. Swift SVN r15872
Swift SVN r15730
order rdar://problem/16408837 Swift SVN r15505