[NameLookup] Collect implicit opaque GenericParams

Plain protocols with generic type paramters should
be collected as opaque types.

Author: angela-laar

include/swift/AST/TypeRepr.h

@@ -406,6 +406,13 @@ class GenericIdentTypeRepr final
     return {getTrailingObjects<TypeRepr*>(),
             Bits.GenericIdentTypeRepr.NumGenericArgs};
   }
+
+  bool argsAreProtocols(DeclContext *dc) {
+    return llvm::any_of(getGenericArgs(), [&](TypeRepr *genericArg) {
+      return genericArg->isProtocol(dc);
+    });
+  }
+
   SourceRange getAngleBrackets() const { return AngleBrackets; }
 
   static bool classof(const TypeRepr *T) {

lib/AST/NameLookup.cpp

@@ -2801,7 +2801,6 @@ bool TypeRepr::isProtocol(DeclContext *dc){
   });
 }
 
-
 static GenericParamList *
 createExtensionGenericParams(ASTContext &ctx,
                              ExtensionDecl *ext,
@@ -2847,15 +2846,19 @@ CollectedOpaqueReprs swift::collectOpaqueReturnTypeReprs(TypeRepr *r, ASTContext
 
       if (auto existential = dyn_cast<ExistentialTypeRepr>(repr)) {
         return Action::SkipChildren();
-      } else if (auto compositionRepr = dyn_cast<CompositionTypeRepr>(repr)) {
-        if (!compositionRepr->isTypeReprAny())
-          Reprs.push_back(compositionRepr);
+      } else if (auto composition = dyn_cast<CompositionTypeRepr>(repr)) {
+        if (!composition->isTypeReprAny())
+          Reprs.push_back(composition);
         return Action::SkipChildren();
       } else if (auto generic = dyn_cast<GenericIdentTypeRepr>(repr)) {
-        return Action::Continue();
-      } else if (auto declRefTR = dyn_cast<DeclRefTypeRepr>(repr)) {
-        if (declRefTR->isProtocol(dc))
-          Reprs.push_back(declRefTR);
+        if (generic->isProtocol(dc))
+          Reprs.push_back(generic);
+        if (generic->argsAreProtocols(dc))
+          return Action::Continue();
+        return Action::SkipChildren();
+      } else if (auto declRef = dyn_cast<DeclRefTypeRepr>(repr)) {
+        if (declRef->isProtocol(dc))
+          Reprs.push_back(declRef);
       }
       return Action::Continue();
     }