Fix #2872 (#2898)

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/jvm/StubGenerator.kt

@@ -885,6 +885,8 @@ class StubGenerator(
             if (configuration.library.language == Language.OBJECTIVE_C) {
                 add("CONFLICTING_OVERLOADS")
                 add("RETURN_TYPE_MISMATCH_ON_INHERITANCE")
+                add("PROPERTY_TYPE_MISMATCH_ON_INHERITANCE") // Multiple-inheriting property with conflicting types
+                add("VAR_TYPE_MISMATCH_ON_INHERITANCE") // Multiple-inheriting mutable property with conflicting types
                 add("RETURN_TYPE_MISMATCH_ON_OVERRIDE")
                 add("WRONG_MODIFIER_CONTAINING_DECLARATION") // For `final val` in interface.
                 add("PARAMETER_NAME_CHANGED_ON_OVERRIDE")

backend.native/tests/interop/objc/smoke.h

@@ -159,4 +159,20 @@ NSObject* createNSObject() {
 @interface TestOverrideInit : NSObject
 -(instancetype)initWithValue:(int)value NS_DESIGNATED_INITIALIZER;
 +(instancetype)createWithValue:(int)value;
-@end;
+@end;
+
+@interface MultipleInheritanceClashBase : NSObject
+@property (nonnull) MultipleInheritanceClashBase* delegate;
+@end;
+
+@protocol MultipleInheritanceClash
+@optional
+@property (nullable) id<MultipleInheritanceClash> delegate;
+@end;
+
+@interface MultipleInheritanceClash1 : MultipleInheritanceClashBase <MultipleInheritanceClash>
+@end;
+
+@interface MultipleInheritanceClash2 : MultipleInheritanceClashBase <MultipleInheritanceClash>
+@property MultipleInheritanceClashBase* delegate;
+@end;

backend.native/tests/interop/objc/smoke.kt

@@ -23,6 +23,7 @@ fun run() {
     testCustomRetain()
     testVarargs()
     testOverrideInit()
+    testMultipleInheritanceClash()
 
     assertEquals(2, ForwardDeclaredEnum.TWO.value)
 
@@ -310,6 +311,21 @@ class TestOverrideInitImpl @OverrideInit constructor(val value: Int) : TestOverr
 
 private class MyException : Throwable()
 
+fun testMultipleInheritanceClash() {
+    val clash1 = MultipleInheritanceClash1()
+    val clash2 = MultipleInheritanceClash2()
+
+    clash1.delegate = clash1
+    assertEquals(clash1, clash1.delegate)
+    clash1.setDelegate(clash2)
+    assertEquals(clash2, clash1.delegate())
+
+    clash2.delegate = clash1
+    assertEquals(clash1, clash2.delegate)
+    clash2.setDelegate(clash2)
+    assertEquals(clash2, clash2.delegate())
+}
+
 fun nsArrayOf(vararg elements: Any): NSArray = NSMutableArray().apply {
     elements.forEach {
         this.addObject(it as ObjCObject)

backend.native/tests/interop/objc/smoke.m

@@ -154,4 +154,13 @@ static CustomRetainMethodsImpl* retainedCustomRetainMethodsImpl;
 +(instancetype)createWithValue:(int)value {
     return [[self alloc] initWithValue:value];
 }
-@end;
+@end;
+
+@implementation MultipleInheritanceClashBase
+@end;
+
+@implementation MultipleInheritanceClash1
+@end;
+
+@implementation MultipleInheritanceClash2
+@end;