[ClangImporter] Import 'Class<SomeProto>' as 'SomeProto.Type'. (#3185)

Swift has supported this for a long time using manual casts and going
from Swift to Objective-C; just enable it now for the importer.

rdar://problem/15101588

Author: jrose-apple

lib/ClangImporter/ImportType.cpp

@@ -901,27 +901,28 @@ namespace {
         return { importedType, ImportHint::ObjCPointer };
       }
 
-      // If this is id<P>, turn this into a protocol type.
-      // FIXME: What about Class<P>?
-      if (type->isObjCQualifiedIdType()) {
+      // If this is id<P> or Class<P>, turn this into a protocol type.
+      if (type->isObjCQualifiedIdType() || type->isObjCQualifiedClassType()) {
         SmallVector<Type, 4> protocols;
         for (auto cp = type->qual_begin(), cpEnd = type->qual_end();
              cp != cpEnd; ++cp) {
-          auto proto = cast_or_null<ProtocolDecl>(Impl.importDecl(*cp,
-                                                                  false));
+          auto proto = cast_or_null<ProtocolDecl>(Impl.importDecl(*cp, false));
           if (!proto)
             return Type();
 
           protocols.push_back(proto->getDeclaredType());
         }
 
-        return { ProtocolCompositionType::get(Impl.SwiftContext, protocols),
-                 ImportHint::ObjCPointer };
+        Type result = ProtocolCompositionType::get(Impl.SwiftContext,
+                                                   protocols);
+        if (type->isObjCQualifiedClassType())
+          result = ExistentialMetatypeType::get(result);
+
+        return { result, ImportHint::ObjCPointer };
       }
 
       // Beyond here, we're using AnyObject.
-      auto proto = Impl.SwiftContext.getProtocol(
-                     KnownProtocolKind::AnyObject);
+      auto proto = Impl.SwiftContext.getProtocol(KnownProtocolKind::AnyObject);
       if (!proto)
         return Type();
 
@@ -931,7 +932,7 @@ namespace {
       }
 
       // Class maps to AnyObject.Type.
-      assert(type->isObjCClassType() || type->isObjCQualifiedClassType());
+      assert(type->isObjCClassType());
       return { ExistentialMetatypeType::get(proto->getDeclaredType()),
                ImportHint::ObjCPointer };
     }

test/ClangModules/Inputs/custom-modules/Protocols.h

@@ -2,3 +2,10 @@
 @property int bar;
 @end
 
+@protocol AnotherProto
+@end
+
+Class <FooProto> _Nonnull processFooType(Class <FooProto> _Nonnull);
+Class <FooProto, AnotherProto> _Nonnull processComboType(Class <FooProto, AnotherProto> _Nonnull);
+Class <AnotherProto, FooProto> _Nonnull processComboType2(Class <AnotherProto, FooProto> _Nonnull);
+

test/ClangModules/objc_ir.swift

@@ -110,6 +110,49 @@ func getset(p p: FooProto) {
   p.bar = prop
 }
 
+// CHECK-LABEL: define hidden %swift.type* @_TF7objc_ir16protocolMetatypeFT1pPSo8FooProto__PMPS0__(%objc_object*) {{.*}} {
+func protocolMetatype(p: FooProto) -> FooProto.Type {
+  // CHECK: = call %swift.type* @swift_getObjectType(%objc_object* %0)
+  // CHECK-NOT: {{retain|release}}
+  // CHECK: [[RAW_RESULT:%.+]] = call i8* @processFooType(i8* {{%.+}})
+  // CHECK: [[CASTED_RESULT:%.+]] = bitcast i8* [[RAW_RESULT]] to %objc_class*
+  // CHECK: [[SWIFT_RESULT:%.+]] = call %swift.type* @swift_getObjCClassMetadata(%objc_class* [[CASTED_RESULT]])
+  // CHECK: call void @swift_unknownRelease(%objc_object* %0)
+  // CHECK: ret %swift.type* [[SWIFT_RESULT]]
+  let type = processFooType(p.dynamicType)
+  return type
+} // CHECK: }
+
+class Impl: FooProto, AnotherProto {
+  @objc var bar: Int32 = 0
+}
+
+// CHECK-LABEL: define hidden %swift.type* @_TF7objc_ir27protocolCompositionMetatypeFT1pCS_4Impl_PMPSo12AnotherProtoSo8FooProto_(%C7objc_ir4Impl*) {{.*}} {
+func protocolCompositionMetatype(p: Impl) -> protocol<FooProto, AnotherProto>.Type {
+  // CHECK: = getelementptr inbounds %C7objc_ir4Impl, %C7objc_ir4Impl* %0, i32 0, i32 0, i32 0
+  // CHECK-NOT: {{retain|release}}
+  // CHECK: [[RAW_RESULT:%.+]] = call i8* @processComboType(i8* {{%.+}})
+  // CHECK: [[CASTED_RESULT:%.+]] = bitcast i8* [[RAW_RESULT]] to %objc_class*
+  // CHECK: [[SWIFT_RESULT:%.+]] = call %swift.type* @swift_getObjCClassMetadata(%objc_class* [[CASTED_RESULT]])
+  // CHECK: call void bitcast (void (%swift.refcounted*)* @rt_swift_release to void (%C7objc_ir4Impl*)*)(%C7objc_ir4Impl* %0)
+  // CHECK: ret %swift.type* [[SWIFT_RESULT]]
+  let type = processComboType(p.dynamicType)
+  return type
+} // CHECK: }
+
+// CHECK-LABEL: define hidden %swift.type* @_TF7objc_ir28protocolCompositionMetatype2FT1pCS_4Impl_PMPSo12AnotherProtoSo8FooProto_(%C7objc_ir4Impl*) {{.*}} {
+func protocolCompositionMetatype2(p: Impl) -> protocol<FooProto, AnotherProto>.Type {
+  // CHECK: = getelementptr inbounds %C7objc_ir4Impl, %C7objc_ir4Impl* %0, i32 0, i32 0, i32 0
+  // CHECK-NOT: {{retain|release}}
+  // CHECK: [[RAW_RESULT:%.+]] = call i8* @processComboType2(i8* {{%.+}})
+  // CHECK: [[CASTED_RESULT:%.+]] = bitcast i8* [[RAW_RESULT]] to %objc_class*
+  // CHECK: [[SWIFT_RESULT:%.+]] = call %swift.type* @swift_getObjCClassMetadata(%objc_class* [[CASTED_RESULT]])
+  // CHECK: call void bitcast (void (%swift.refcounted*)* @rt_swift_release to void (%C7objc_ir4Impl*)*)(%C7objc_ir4Impl* %0)
+  // CHECK: ret %swift.type* [[SWIFT_RESULT]]
+  let type = processComboType2(p.dynamicType)
+  return type
+} // CHECK: }
+
 // CHECK-LABEL: define hidden void @_TF7objc_ir17pointerPropertiesFCSo14PointerWrapperT_(%CSo14PointerWrapper*) {{.*}} {
 func pointerProperties(_ obj: PointerWrapper) {
   // CHECK: load i8*, i8** @"\01L_selector(setVoidPtr:)"

test/PrintAsObjC/classes.swift

@@ -233,6 +233,7 @@ typealias AliasForNSRect = NSRect
 // CHECK-NEXT: - (NSArray * _Nonnull)emptyArray;
 // CHECK-NEXT: - (NSArray * _Nullable)maybeArray;
 // CHECK-NEXT: - (NSRuncingMode)someEnum;
+// CHECK-NEXT: - (Class <NSCoding> _Nullable)protocolClass;
 // CHECK-NEXT: - (struct _NSZone * _Nullable)zone;
 // CHECK-NEXT: - (CFTypeRef _Nullable)cf:(CFTreeRef _Nonnull)x str:(CFStringRef _Nonnull)str str2:(CFMutableStringRef _Nonnull)str2 obj:(CFAliasForTypeRef _Nonnull)obj;
 // CHECK-NEXT: - (void)appKitInImplementation;
@@ -248,6 +249,7 @@ typealias AliasForNSRect = NSRect
   func maybeArray() -> NSArray? { return nil }
 
   func someEnum() -> RuncingMode { return .mince }
+  func protocolClass() -> NSCoding.Type? { return nil }
 
   func zone() -> NSZone? { return nil }
 

test/SILGen/objc_ownership_conventions.swift

@@ -116,16 +116,18 @@ func test11(_ g: Gizmo) -> AnyClass {
   // CHECK: bb0([[G:%[0-9]+]] : $Gizmo):
   // CHECK: strong_retain [[G]]
   // CHECK: [[NS_G:%[0-9]+]] = upcast [[G:%[0-9]+]] : $Gizmo to $NSObject
-  // CHECK: [[GETTER:%[0-9]+]] = class_method [volatile] [[NS_G]] : $NSObject, #NSObject.qualifiedClassProp!getter.1.foreign : NSObject -> () -> AnyObject.Type! , $@convention(objc_method) (NSObject) -> ImplicitlyUnwrappedOptional<@objc_metatype AnyObject.Type>
-  // CHECK-NEXT: [[OPT_OBJC:%.*]] = apply [[GETTER]]([[NS_G]]) : $@convention(objc_method) (NSObject) -> ImplicitlyUnwrappedOptional<@objc_metatype AnyObject.Type>
+  // CHECK: [[GETTER:%[0-9]+]] = class_method [volatile] [[NS_G]] : $NSObject, #NSObject.qualifiedClassProp!getter.1.foreign : NSObject -> () -> NSAnsing.Type! , $@convention(objc_method) (NSObject) -> ImplicitlyUnwrappedOptional<@objc_metatype NSAnsing.Type>
+  // CHECK-NEXT: [[OPT_OBJC:%.*]] = apply [[GETTER]]([[NS_G]]) : $@convention(objc_method) (NSObject) -> ImplicitlyUnwrappedOptional<@objc_metatype NSAnsing.Type>
   // CHECK:      select_enum [[OPT_OBJC]]
   // CHECK:      [[OBJC:%.*]] = unchecked_enum_data [[OPT_OBJC]]
   // CHECK-NEXT: [[THICK:%.*]] = objc_to_thick_metatype [[OBJC]]
-  // CHECK:      [[T0:%.*]] = enum $ImplicitlyUnwrappedOptional<AnyObject.Type>, #ImplicitlyUnwrappedOptional.some!enumelt.1, [[THICK]]
+  // CHECK:      [[T0:%.*]] = enum $ImplicitlyUnwrappedOptional<NSAnsing.Type>, #ImplicitlyUnwrappedOptional.some!enumelt.1, [[THICK]]
   // CHECK:      [[RES:%.*]] = unchecked_enum_data
+  // CHECK:      [[OPENED:%.*]] = open_existential_metatype [[RES]]
+  // CHECK:      [[RES_ANY:%.*]] = init_existential_metatype [[OPENED]]
   // CHECK:      strong_release [[G]] : $Gizmo
   // CHECK:      strong_release [[G]] : $Gizmo
-  // CHECK-NEXT: return [[RES]] : $@thick AnyObject.Type
+  // CHECK-NEXT: return [[RES_ANY]] : $@thick AnyObject.Type
   return g.qualifiedClassProp
 }