Merge pull request #4053 from rudkx/fix-27671033

Fix crash during type checking when adding members to an extension.

Author: tkremenek

lib/AST/NameLookup.cpp

@@ -898,6 +898,9 @@ void NominalTypeDecl::addedMember(Decl *member) {
 
 void ExtensionDecl::addedMember(Decl *member) {
   if (NextExtension.getInt()) {
+    if (getExtendedType()->is<ErrorType>())
+      return;
+
     auto nominal = getExtendedType()->getAnyNominal();
     if (nominal->LookupTable.getPointer()) {
       // Make sure we have the complete list of extensions.

test/decl/var/properties.swift

@@ -1133,6 +1133,13 @@ extension rdar17391625derived {
   }
 }
 
+// <rdar://problem/27671033> Crash when defining property inside an invalid extension
+public protocol rdar27671033P {}
+struct rdar27671033S<Key, Value> {}
+extension rdar27671033S : rdar27671033P where Key == String { // expected-error {{extension of type 'rdar27671033S' with constraints cannot have an inheritance clause}}
+  // expected-error@-1 {{same-type requirement makes generic parameter 'Key' non-generic}}
+  let d = rdar27671033S<Int, Int>() // expected-error {{extensions may not contain stored properties}}
+}
 
 // <rdar://problem/19874152> struct memberwise initializer violates new sanctity of previously set `let` property
 struct r19874152S1 {