One last name lookup cleanup

lib/Sema/CSSimplify.cpp

@@ -3092,11 +3092,6 @@ performMemberLookup(ConstraintKind constraintKind, DeclName memberName,
     if (includeInaccessibleMembers)
       lookupOptions |= NameLookupFlags::IgnoreAccessibility;
 
-    // If a constructor is only visible as a witness for a protocol
-    // requirement, it must be an invalid override. Also, protocol
-    // extensions cannot yet define designated initializers.
-    lookupOptions -= NameLookupFlags::PerformConformanceCheck;
-
     LookupResult ctors = TC.lookupConstructors(DC, instanceTy, lookupOptions);
     if (!ctors)
       return result;    // No result.

lib/Sema/TypeCheckNameLookup.cpp

@@ -129,6 +129,12 @@ namespace {
 
       assert(isa<ProtocolDecl>(foundDC));
 
+      if (!Options.contains(NameLookupFlags::PerformConformanceCheck))
+        return;
+
+      // If we found something within the protocol itself, and our
+      // search began somewhere that is not in a protocol or extension
+      // thereof, remap this declaration to the witness.
       auto conformingType = foundInType;
 
       // When performing a lookup on a subclass existential, we might
@@ -143,52 +149,43 @@ namespace {
           conformingType = layout.superclass;
       }
 
-      // If we found something within the protocol itself, and our
-      // search began somewhere that is not in a protocol or extension
-      // thereof, remap this declaration to the witness.
-      if (foundInType->is<ArchetypeType>() ||
-          foundInType->isExistentialType() ||
-          Options.contains(NameLookupFlags::PerformConformanceCheck)) {
-        // Dig out the protocol conformance.
-        auto conformance = TC.conformsToProtocol(conformingType, foundProto, DC,
+      // Dig out the protocol conformance.
+      auto conformance = TC.conformsToProtocol(conformingType, foundProto, DC,
                                                  conformanceOptions);
-        if (!conformance) {
-          // If there's no conformance, we have an existential
-          // and we found a member from one of the protocols, and
-          // not a class constraint if any.
-          assert(foundInType->isExistentialType());
-          addResult(found);
-          return;
-        }
-
-        if (conformance->isAbstract()) {
-          assert(foundInType->is<ArchetypeType>() ||
-                 foundInType->isExistentialType());
-          addResult(found);
-          return;
-        }
-
-        // Dig out the witness.
-        ValueDecl *witness = nullptr;
-        auto concrete = conformance->getConcrete();
-        if (auto assocType = dyn_cast<AssociatedTypeDecl>(found)) {
-          witness = concrete->getTypeWitnessAndDecl(assocType, &TC)
-            .second;
-        } else if (found->isProtocolRequirement()) {
-          witness = concrete->getWitnessDecl(found, &TC);
-        }
-
-        // FIXME: the "isa<ProtocolDecl>()" check will be wrong for
-        // default implementations in protocols.
-        //
-        // If we have an imported conformance or the witness could
-        // not be deserialized, getWitnessDecl() will just return
-        // the requirement, so just drop the lookup result here.
-        if (witness && !isa<ProtocolDecl>(witness->getDeclContext()))
-          addResult(witness);
+      if (!conformance) {
+        // If there's no conformance, we have an existential
+        // and we found a member from one of the protocols, and
+        // not a class constraint if any.
+        assert(foundInType->isExistentialType());
+        addResult(found);
+        return;
+      }
 
+      if (conformance->isAbstract()) {
+        assert(foundInType->is<ArchetypeType>() ||
+               foundInType->isExistentialType());
+        addResult(found);
         return;
       }
+
+      // Dig out the witness.
+      ValueDecl *witness = nullptr;
+      auto concrete = conformance->getConcrete();
+      if (auto assocType = dyn_cast<AssociatedTypeDecl>(found)) {
+        witness = concrete->getTypeWitnessAndDecl(assocType, &TC)
+          .second;
+      } else if (found->isProtocolRequirement()) {
+        witness = concrete->getWitnessDecl(found, &TC);
+      }
+
+      // FIXME: the "isa<ProtocolDecl>()" check will be wrong for
+      // default implementations in protocols.
+      //
+      // If we have an imported conformance or the witness could
+      // not be deserialized, getWitnessDecl() will just return
+      // the requirement, so just drop the lookup result here.
+      if (witness && !isa<ProtocolDecl>(witness->getDeclContext()))
+        addResult(witness);
     }
   };
 } // end anonymous namespace

test/Sema/diag_invalid_synthesized_init_proto_conformance.swift

@@ -8,14 +8,14 @@ class A : P { } // expected-error{{initializer requirement 'init()' can only be
 // No further errors
 
 class B : A {
-    init(x : Int) {} // expected-note {{'init(x:)' declared here}}
+    init(x : Int) {}
 }
 
 class C : B { }
 
 class D : B {
   init() {
-    super.init() // expected-error{{missing argument for parameter 'x' in call}}
+    super.init()
   }
 }