Sema: More checkConformance() => lookupConformance()

Author: slavapestov

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -1396,7 +1396,7 @@ static void diagnoseClassWithoutInitializers(ClassDecl *classDecl) {
   if (auto *superclassDecl = classDecl->getSuperclassDecl()) {
     auto *decodableProto = C.getProtocol(KnownProtocolKind::Decodable);
     auto superclassType = superclassDecl->getDeclaredInterfaceType();
-    auto ref = classDecl->getParentModule()->checkConformance(
+    auto ref = classDecl->getParentModule()->lookupConformance(
         superclassType, decodableProto);
     if (ref) {
       // super conforms to Decodable, so we've failed to inherit init(from:).
@@ -1425,7 +1425,7 @@ static void diagnoseClassWithoutInitializers(ClassDecl *classDecl) {
       // likely that the user forgot to override its encode(to:). In this case,
       // we can produce a slightly different diagnostic to suggest doing so.
       auto *encodableProto = C.getProtocol(KnownProtocolKind::Encodable);
-      auto ref = classDecl->getParentModule()->checkConformance(
+      auto ref = classDecl->getParentModule()->lookupConformance(
           superclassType, encodableProto);
       if (ref) {
         // We only want to produce this version of the diagnostic if the

test/decl/protocol/special/coding/class_codable_inheritance_diagnostics.swift

@@ -97,3 +97,13 @@ class EncodableSubWithoutInitialValue : CodableSuper { // expected-error {{class
 class CodableSubWithInitialValue : CodableSuper {
   var value2 = 10
 }
+
+class GenericCodableSuper<T>: Decodable {}
+
+class GenericCodableSub<T>: GenericCodableSuper<T> {
+// expected-error@-1 {{class 'GenericCodableSub' has no initializers}}
+// expected-note@-2 {{did you mean to override 'init(from:)'?}}
+// expected-warning@-2 {{'required' initializer 'init(from:)' must be provided by subclass of 'GenericCodableSuper<T>'; this is an error in Swift 6}}
+  var t: T
+  // expected-note@-1 {{stored property 't' without initial value prevents synthesized initializers}}
+}