Commits
Joe Groff committed ce456b685af
AST: Handle substitution of an existential for an archetype in Substitution::subst. Existentials have null conformances too, so don't try vainly to dig their conformances out of the substitution substitutions. Fixes <rdar://problem/16534083> and a couple of XFAILed tests under <rdar://problem/16533367>. Swift SVN r15994