Merge pull request #27622 from aschwaighofer/irgen_fix_protocol_any_object_to_protocol_composition_with_superclass

IRGen: Fix cast of existential type with anyobject to super class constraint existential

Author: aschwaighofer

lib/IRGen/GenCast.cpp

@@ -638,8 +638,12 @@ void irgen::emitScalarExistentialDowncast(IRGenFunction &IGF,
   bool checkSuperclassConstraint = false;
   if (hasSuperclassConstraint) {
     Type srcSuperclassType = srcInstanceType;
-    if (srcSuperclassType->isExistentialType())
+    if (srcSuperclassType->isExistentialType()) {
       srcSuperclassType = srcSuperclassType->getSuperclass();
+      // Look for an AnyObject superclass (getSuperclass() returns nil).
+      if (!srcSuperclassType && srcInstanceType->isClassExistentialType())
+        checkSuperclassConstraint = true;
+    }
     if (srcSuperclassType) {
       checkSuperclassConstraint =
         !destInstanceType->getSuperclass()->isExactSuperclassOf(

test/IRGen/casts.sil

@@ -359,3 +359,51 @@ entry(%a : $OA):
   %b = unconditional_checked_cast %a : $OA to $OB
   return %b : $OB
 }
+
+protocol P {}
+protocol PAnyObject: AnyObject {}
+class C {}
+sil_vtable C {}
+
+// CHECK-LABEL: define{{.*}} @cast_protocol_composition_with_anyobject
+// CHECK: [[C:%.*]] = call swiftcc %swift.metadata_response @"$s5casts1CCMa"
+// CHECK: [[C_META:%.*]] = extractvalue %swift.metadata_response [[C]], 0
+// CHECK: call { i8*, i8** } @dynamic_cast_existential_1_superclass_conditional({{.*}}, %swift.type* [[C_META]], %swift.protocol* {{.*}}@"$s5casts1PMp"
+
+sil @cast_protocol_composition_with_anyobject : $@convention(thin) (@owned P & AnyObject ) -> @owned Optional<C & P> {
+bb0(%0: $P & AnyObject):
+  checked_cast_br %0 : $P & AnyObject to $C & P, bb1, bb2
+
+bb1(%2 : $C & P):
+  %3 = enum $Optional<C & P>, #Optional.some!enumelt.1, %2 : $C & P
+  br bb3(%3 : $Optional<C & P>)
+
+bb2:
+  strong_release %0 : $P & AnyObject
+  %6 = enum $Optional<C & P>, #Optional.none!enumelt
+  br bb3(%6 : $Optional<C & P>)
+
+bb3(%11 : $Optional<C & P>):
+  return %11 : $Optional<C & P>
+}
+
+// CHECK-LABEL: define{{.*}} @cast_protocol_with_anyobject
+// CHECK: [[C:%.*]] = call swiftcc %swift.metadata_response @"$s5casts1CCMa"
+// CHECK: [[C_META:%.*]] = extractvalue %swift.metadata_response [[C]], 0
+// CHECK: call { i8*, i8** } @dynamic_cast_existential_1_superclass_conditional({{.*}}, %swift.type* [[C_META]], %swift.protocol* {{.*}}@"$s5casts10PAnyObjectMp"
+sil @cast_protocol_with_anyobject : $@convention(thin) (@owned PAnyObject ) -> @owned Optional<C & PAnyObject> {
+bb0(%0: $PAnyObject):
+  checked_cast_br %0 : $PAnyObject to $C & PAnyObject, bb1, bb2
+
+bb1(%2 : $C & PAnyObject):
+  %3 = enum $Optional<C & PAnyObject>, #Optional.some!enumelt.1, %2 : $C & PAnyObject
+  br bb3(%3 : $Optional<C & PAnyObject>)
+
+bb2:
+  strong_release %0 : $PAnyObject
+  %6 = enum $Optional<C & PAnyObject>, #Optional.none!enumelt
+  br bb3(%6 : $Optional<C & PAnyObject>)
+
+bb3(%11 : $Optional<C & PAnyObject>):
+  return %11 : $Optional<C & PAnyObject>
+}

test/Interpreter/casts.swift

@@ -122,3 +122,23 @@ Casts.test("testConditionalBridgedCastFromSwiftToNSObjectDerivedClass") {
   }
   expectEqual(0, LifetimeTracked.instances)
 }
+
+protocol Q {}
+class K { }
+class D: Q {}
+typealias AnyQ = Q & AnyObject
+typealias KQ = K & Q
+
+Casts.test("testCastProtocolCompoWithAnyObjectToProtocolCompoTypeSuperclass") {
+  let shouldBeNil = (D() as AnyQ) as? KQ
+  expectNil(shouldBeNil)
+}
+
+protocol QAny: AnyObject {}
+typealias KQAny = K & QAny
+class F: QAny {}
+
+Casts.test("testCastProtocolWithAnyObjectToProtocolCompoTypeSuperclass") {
+  let shouldBeNil = (F() as QAny) as? KQAny
+  expectNil(shouldBeNil)
+}