SIL: Fix type lowering of unowned reference to class-bound generic parameter [5.4]

lib/SIL/IR/TypeLowering.cpp

@@ -414,8 +414,15 @@ namespace {
       return visitAbstractTypeParamType(type, origType, isSensitive);
     }
 
-    Type getConcreteReferenceStorageReferent(Type type) {
+    Type getConcreteReferenceStorageReferent(Type type,
+                                             AbstractionPattern origType) {
       if (type->isTypeParameter()) {
+        auto genericSig = origType.getGenericSignature();
+        if (auto concreteType = genericSig->getConcreteType(type))
+          return concreteType;
+        if (auto superclassType = genericSig->getSuperclassBound(type))
+          return superclassType;
+        assert(genericSig->requiresClass(type));
         return TC.Context.getAnyObjectType();
       }
 
@@ -460,7 +467,7 @@ namespace {
                                    IsTypeExpansionSensitive_t isSensitive) { \
       auto referentType = \
         type->getReferentType()->lookThroughSingleOptionalType(); \
-      auto concreteType = getConcreteReferenceStorageReferent(referentType); \
+      auto concreteType = getConcreteReferenceStorageReferent(referentType, origType); \
       if (Name##StorageType::get(concreteType, TC.Context) \
             ->isLoadable(Expansion.getResilienceExpansion())) { \
         return asImpl().visitLoadable##Name##StorageType(type, origType, \

test/SILGen/unowned-class-bound-generic-parameter.swift

@@ -0,0 +1,23 @@
+// RUN: %target-swift-emit-silgen %s -enable-objc-interop | %FileCheck %s
+
+protocol ClassProtocol: AnyObject {}
+
+class BaseClass {}
+
+func makeGenericClosureWithUnknownClass<T>(t: T) where T : ClassProtocol {
+  _ = { [unowned t] in _ = t }
+}
+
+// CHECK-LABEL: sil private [ossa] @$s4main34makeGenericClosureWithUnknownClass1tyx_tAA0G8ProtocolRzlFyycfU_ : $@convention(thin) <T where T : ClassProtocol> (@guaranteed <τ_0_0 where τ_0_0 : ClassProtocol> { var @sil_unowned τ_0_0 } <T>) -> () {
+
+func makeGenericClosureWithNativeClass1<T>(t: T) where T : BaseClass {
+  _ = { [unowned t] in _ = t }
+}
+
+// CHECK-LABEL: sil private [ossa] @$s4main34makeGenericClosureWithNativeClass11tyx_tAA9BaseClassCRbzlFyycfU_ : $@convention(thin) <T where T : BaseClass> (@guaranteed @sil_unowned T) -> () {
+
+func makeGenericClosureWithNativeClass2<T>(t: T) where T : ClassProtocol, T : BaseClass {
+  _ = { [unowned t] in _ = t }
+}
+
+// CHECK-LABEL: sil private [ossa] @$s4main34makeGenericClosureWithNativeClass21tyx_tAA9BaseClassCRbzAA0I8ProtocolRzlFyycfU_ : $@convention(thin) <T where T : BaseClass, T : ClassProtocol> (@guaranteed @sil_unowned T) -> () {