Merge pull request #10440 from slavapestov/abstract-conformance-versus-concrete-nested-type-ugh-not-again-4.0

AST: Tweak a concrete-nested-type-of-archetype hack slightly [4.0]

Author: tkremenek

lib/AST/SubstitutionMap.cpp

@@ -223,7 +223,8 @@ SubstitutionMap::lookupConformance(CanType type, ProtocolDecl *proto) const {
       auto *M = proto->getParentModule();
       auto substType = type.subst(*this);
       if (substType &&
-          !substType->is<ArchetypeType>() &&
+          (!substType->is<ArchetypeType>() ||
+           substType->castTo<ArchetypeType>()->getSuperclass()) &&
           !substType->isTypeParameter() &&
           !substType->isExistentialType()) {
         auto lazyResolver = M->getASTContext().getLazyResolver();

validation-test/compiler_crashers_2_fixed/0108-sr4088.swift

@@ -0,0 +1,23 @@
+// RUN: %target-swift-frontend -emit-ir -primary-file %s
+
+class UITableViewCell {}
+class UITableView {}
+
+extension UITableViewCell: ReusableViewProtocol {
+    public typealias ParentView = UITableView
+}
+
+protocol ReusableViewProtocol {
+    associatedtype ParentView
+}
+
+protocol ReusableViewFactoryProtocol {
+    associatedtype View: ReusableViewProtocol
+    func configure(parentView: View.ParentView)
+}
+
+extension ReusableViewFactoryProtocol where View: UITableViewCell {
+    func tableCellFor(tableView: UITableView) {
+        configure(parentView: tableView)
+    }
+}