KT-1934 Check inherited signatures for compatibility

Overridden signatures should have compatible return types
(equal types for 'var').
Only relevant overrides should be taken into account.
Refactor inherited signatures check,
introduce a strategy interface for problem reporting.

compiler/testData/diagnostics/tests/override/MultipleDefaultsAndNamesInSupertypes.kt

@@ -7,7 +7,8 @@ open class B {
 }
 
 interface C {
-    fun foo(y: Int)
+    fun foo(y: Int): Int
 }
 
-<!MULTIPLE_DEFAULTS_INHERITED_FROM_SUPERTYPES_WHEN_NO_EXPLICIT_OVERRIDE, DIFFERENT_NAMES_FOR_THE_SAME_PARAMETER_IN_SUPERTYPES!>class Z<!> : A, B(), C
+// TODO DIFFERENT_NAMES_FOR_THE_SAME_PARAMETER_IN_SUPERTYPES reported twice
+<!MULTIPLE_DEFAULTS_INHERITED_FROM_SUPERTYPES_WHEN_NO_EXPLICIT_OVERRIDE, DIFFERENT_NAMES_FOR_THE_SAME_PARAMETER_IN_SUPERTYPES, DIFFERENT_NAMES_FOR_THE_SAME_PARAMETER_IN_SUPERTYPES!>class Z<!> : A, B(), C

compiler/testData/diagnostics/tests/override/MultipleDefaultsAndNamesInSupertypes.txt

@@ -17,7 +17,7 @@ public open class B {
 
 public interface C {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public abstract fun foo(/*0*/ y: kotlin.Int): kotlin.Unit
+    public abstract fun foo(/*0*/ y: kotlin.Int): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
@@ -25,7 +25,7 @@ public interface C {
 public final class Z : A, B, C {
     public constructor Z()
     public open override /*3*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public final override /*3*/ /*fake_override*/ fun foo(/*0*/ x: kotlin.Int = ...): kotlin.Int
+    public final override /*3*/ /*fake_override*/ fun foo(/*0*/ y: kotlin.Int = ...): kotlin.Int
     public open override /*3*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*3*/ /*fake_override*/ fun toString(): kotlin.String
 }

compiler/testData/diagnostics/tests/override/clashesOnInheritance/covariantOverrides.kt

@@ -0,0 +1,37 @@
+interface IBase {
+    fun copy(): IBase
+}
+
+interface ILeft : IBase {
+    override fun copy(): ILeft
+}
+
+open class CLeft : ILeft {
+    override fun copy(): ILeft = CLeft()
+}
+
+interface IRight : IBase {
+    override fun copy(): IRight
+}
+
+interface IDerived : ILeft, IRight {
+    override fun copy(): IDerived
+}
+
+// Error: ILeft::copy and IRight::copy have unrelated return types
+<!RETURN_TYPE_MISMATCH_ON_INHERITANCE, ABSTRACT_MEMBER_NOT_IMPLEMENTED!>class CDerivedInvalid1<!> : ILeft, IRight
+
+// Error: CLeft::copy and IRight::copy have unrelated return types
+<!RETURN_TYPE_MISMATCH_ON_INHERITANCE!>class CDerivedInvalid2<!> : CLeft(), IRight
+
+// OK: CDerived1::copy overrides both ILeft::copy and IRight::copy
+class CDerived1 : ILeft, IRight {
+    override fun copy(): CDerived1 = CDerived1()
+}
+
+// Although ILeft::copy and IRight::copy return types are unrelated, IDerived::copy return type is the most specific of three.
+abstract class CDerived2 : ILeft, IRight, IDerived
+
+class CDerived2a : ILeft, IRight, IDerived {
+    override fun copy(): IDerived = CDerived2a()
+}

compiler/testData/diagnostics/tests/override/clashesOnInheritance/covariantOverrides.txt

@@ -0,0 +1,77 @@
+package
+
+public final class CDerived1 : ILeft, IRight {
+    public constructor CDerived1()
+    public open override /*2*/ fun copy(): CDerived1
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public abstract class CDerived2 : ILeft, IRight, IDerived {
+    public constructor CDerived2()
+    public abstract override /*3*/ /*fake_override*/ fun copy(): IDerived
+    public open override /*3*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*3*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*3*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class CDerived2a : ILeft, IRight, IDerived {
+    public constructor CDerived2a()
+    public open override /*3*/ fun copy(): IDerived
+    public open override /*3*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*3*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*3*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class CDerivedInvalid1 : ILeft, IRight {
+    public constructor CDerivedInvalid1()
+    public abstract override /*2*/ /*fake_override*/ fun copy(): ILeft
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class CDerivedInvalid2 : CLeft, IRight {
+    public constructor CDerivedInvalid2()
+    public open override /*2*/ /*fake_override*/ fun copy(): ILeft
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public open class CLeft : ILeft {
+    public constructor CLeft()
+    public open override /*1*/ fun copy(): ILeft
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IBase {
+    public abstract fun copy(): IBase
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IDerived : ILeft, IRight {
+    public abstract override /*2*/ fun copy(): IDerived
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface ILeft : IBase {
+    public abstract override /*1*/ fun copy(): ILeft
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IRight : IBase {
+    public abstract override /*1*/ fun copy(): IRight
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/override/clashesOnInheritance/flexibleReturnType.kt

@@ -0,0 +1,30 @@
+// FILE: J.java
+public interface J {
+    String foo(); // String!
+}
+
+// FILE: K.kt
+interface K1 {
+    fun foo(): String
+}
+
+interface K2 {
+    fun foo(): String?
+}
+
+interface KDerived1a : K1, J
+
+interface KDerived1b : J, K1
+
+interface KDerived2a : K2, J
+
+interface KDerived2b : J, K2
+
+interface KDerived12a : K1, K2, J
+// public abstract override /*3*/ /*fake_override*/ fun foo(): kotlin.String!
+
+<!RETURN_TYPE_MISMATCH_ON_INHERITANCE!>interface KDerived12b<!> : K1, J, K2 // TODO
+// public abstract override /*3*/ /*fake_override*/ fun foo(): kotlin.String?
+
+interface KDerived12c : J, K1, K2
+// public abstract override /*3*/ /*fake_override*/ fun foo(): kotlin.String

compiler/testData/diagnostics/tests/override/clashesOnInheritance/flexibleReturnType.txt

@@ -0,0 +1,73 @@
+package
+
+public /*synthesized*/ fun J(/*0*/ function: () -> kotlin.String!): J
+
+public interface J {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun foo(): kotlin.String!
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface K1 {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun foo(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface K2 {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun foo(): kotlin.String?
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface KDerived12a : K1, K2, J {
+    public open override /*3*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*3*/ /*fake_override*/ fun foo(): kotlin.String!
+    public open override /*3*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*3*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface KDerived12b : K1, J, K2 {
+    public open override /*3*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*3*/ /*fake_override*/ fun foo(): kotlin.String?
+    public open override /*3*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*3*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface KDerived12c : J, K1, K2 {
+    public open override /*3*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*3*/ /*fake_override*/ fun foo(): kotlin.String
+    public open override /*3*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*3*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface KDerived1a : K1, J {
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*2*/ /*fake_override*/ fun foo(): kotlin.String!
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface KDerived1b : J, K1 {
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*2*/ /*fake_override*/ fun foo(): kotlin.String
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface KDerived2a : K2, J {
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*2*/ /*fake_override*/ fun foo(): kotlin.String!
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface KDerived2b : J, K2 {
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*2*/ /*fake_override*/ fun foo(): kotlin.String?
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/override/clashesOnInheritance/propertyTypeMismatch.kt

@@ -0,0 +1,29 @@
+open class A {
+    open val foo: Boolean = true
+}
+
+interface IA {
+    val foo: String
+}
+
+interface IAA {
+    val foo: Int
+}
+
+interface IGA<T> {
+    val foo: T
+}
+
+<!PROPERTY_TYPE_MISMATCH_ON_INHERITANCE!>class B1<!>: A(), IA
+
+<!PROPERTY_TYPE_MISMATCH_ON_INHERITANCE!>class B2<!>: A(), IA, IAA
+
+abstract <!PROPERTY_TYPE_MISMATCH_ON_INHERITANCE!>class B3<!>: IA, IAA
+
+class BS1: A(), IGA<Boolean>
+
+class BS2: A(), IGA<Any>
+
+<!PROPERTY_TYPE_MISMATCH_ON_INHERITANCE!>class BS3<!>: A(), IGA<String>
+
+<!PROPERTY_TYPE_MISMATCH_ON_INHERITANCE!>class BG1<!><T>: A(), IGA<T>

compiler/testData/diagnostics/tests/override/clashesOnInheritance/propertyTypeMismatch.txt

@@ -0,0 +1,86 @@
+package
+
+public open class A {
+    public constructor A()
+    public open val foo: kotlin.Boolean = true
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class B1 : A, IA {
+    public constructor B1()
+    public open override /*2*/ /*fake_override*/ val foo: kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class B2 : A, IA, IAA {
+    public constructor B2()
+    public open override /*3*/ /*fake_override*/ val foo: kotlin.Boolean
+    public open override /*3*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*3*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*3*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public abstract class B3 : IA, IAA {
+    public constructor B3()
+    public abstract override /*2*/ /*fake_override*/ val foo: kotlin.String
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class BG1</*0*/ T> : A, IGA<T> {
+    public constructor BG1</*0*/ T>()
+    public open override /*2*/ /*fake_override*/ val foo: kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class BS1 : A, IGA<kotlin.Boolean> {
+    public constructor BS1()
+    public open override /*2*/ /*fake_override*/ val foo: kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class BS2 : A, IGA<kotlin.Any> {
+    public constructor BS2()
+    public open override /*2*/ /*fake_override*/ val foo: kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class BS3 : A, IGA<kotlin.String> {
+    public constructor BS3()
+    public open override /*2*/ /*fake_override*/ val foo: kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IA {
+    public abstract val foo: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IAA {
+    public abstract val foo: kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGA</*0*/ T> {
+    public abstract val foo: T
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/override/clashesOnInheritance/returnTypeMismatch.kt

@@ -0,0 +1,29 @@
+open class A {
+    open fun foo(): Boolean = true
+}
+
+interface IA {
+    fun foo(): String
+}
+
+interface IAA {
+    fun foo(): Int
+}
+
+interface IGA<T> {
+    fun foo(): T
+}
+
+<!RETURN_TYPE_MISMATCH_ON_INHERITANCE!>class B1<!>: A(), IA
+
+<!RETURN_TYPE_MISMATCH_ON_INHERITANCE!>class B2<!>: A(), IA, IAA
+
+abstract <!RETURN_TYPE_MISMATCH_ON_INHERITANCE!>class B3<!>: IA, IAA
+
+class BS1: A(), IGA<Boolean>
+
+class BS2: A(), IGA<Any>
+
+<!RETURN_TYPE_MISMATCH_ON_INHERITANCE!>class BS3<!>: A(), IGA<String>
+
+<!RETURN_TYPE_MISMATCH_ON_INHERITANCE!>class BG1<!><T>: A(), IGA<T>

compiler/testData/diagnostics/tests/override/clashesOnInheritance/returnTypeMismatch.txt

@@ -0,0 +1,86 @@
+package
+
+public open class A {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open fun foo(): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class B1 : A, IA {
+    public constructor B1()
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun foo(): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class B2 : A, IA, IAA {
+    public constructor B2()
+    public open override /*3*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*3*/ /*fake_override*/ fun foo(): kotlin.Boolean
+    public open override /*3*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*3*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public abstract class B3 : IA, IAA {
+    public constructor B3()
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*2*/ /*fake_override*/ fun foo(): kotlin.String
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class BG1</*0*/ T> : A, IGA<T> {
+    public constructor BG1</*0*/ T>()
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun foo(): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class BS1 : A, IGA<kotlin.Boolean> {
+    public constructor BS1()
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun foo(): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class BS2 : A, IGA<kotlin.Any> {
+    public constructor BS2()
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun foo(): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class BS3 : A, IGA<kotlin.String> {
+    public constructor BS3()
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun foo(): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IA {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun foo(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IAA {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun foo(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGA</*0*/ T> {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun foo(): T
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/override/clashesOnInheritance/unrelatedInherited.kt

@@ -0,0 +1,33 @@
+interface IA {
+    fun method(): String
+    val propVal: String
+    var propVar: String
+}
+
+interface IB1 : IA
+interface IB2 : IA
+
+interface IGA<T> {
+    fun method(): T
+    val propVal: T
+    var propVar: T
+}
+
+interface IGB1Str : IGA<String>
+interface IGB2Str : IGA<String>
+interface IGB3Int : IGA<Int>
+
+interface IGB4T<T> : IGA<T>
+interface IGB5T<T> : IGA<T>
+
+interface IC : IB1, IB2
+
+interface IGC1 : IGB1Str, IGB2Str
+
+interface IGC2 : <!INCONSISTENT_TYPE_PARAMETER_VALUES!>IGB1Str, IGB3Int<!>
+
+interface IGC3<T> : IGB4T<T>, IGB5T<T>
+
+interface IGC4<T> : <!INCONSISTENT_TYPE_PARAMETER_VALUES!>IGB4T<T>, IGB5T<String><!>
+
+interface IGC5 : IGB4T<String>, IGB5T<String>

compiler/testData/diagnostics/tests/override/clashesOnInheritance/unrelatedInherited.txt

@@ -0,0 +1,136 @@
+package
+
+public interface IA {
+    public abstract val propVal: kotlin.String
+    public abstract var propVar: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract fun method(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IB1 : IA {
+    public abstract override /*1*/ /*fake_override*/ val propVal: kotlin.String
+    public abstract override /*1*/ /*fake_override*/ var propVar: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*1*/ /*fake_override*/ fun method(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IB2 : IA {
+    public abstract override /*1*/ /*fake_override*/ val propVal: kotlin.String
+    public abstract override /*1*/ /*fake_override*/ var propVar: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*1*/ /*fake_override*/ fun method(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IC : IB1, IB2 {
+    public abstract override /*2*/ /*fake_override*/ val propVal: kotlin.String
+    public abstract override /*2*/ /*fake_override*/ var propVar: kotlin.String
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*2*/ /*fake_override*/ fun method(): kotlin.String
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGA</*0*/ T> {
+    public abstract val propVal: T
+    public abstract var propVar: T
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract fun method(): T
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGB1Str : IGA<kotlin.String> {
+    public abstract override /*1*/ /*fake_override*/ val propVal: kotlin.String
+    public abstract override /*1*/ /*fake_override*/ var propVar: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*1*/ /*fake_override*/ fun method(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGB2Str : IGA<kotlin.String> {
+    public abstract override /*1*/ /*fake_override*/ val propVal: kotlin.String
+    public abstract override /*1*/ /*fake_override*/ var propVar: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*1*/ /*fake_override*/ fun method(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGB3Int : IGA<kotlin.Int> {
+    public abstract override /*1*/ /*fake_override*/ val propVal: kotlin.Int
+    public abstract override /*1*/ /*fake_override*/ var propVar: kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*1*/ /*fake_override*/ fun method(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGB4T</*0*/ T> : IGA<T> {
+    public abstract override /*1*/ /*fake_override*/ val propVal: T
+    public abstract override /*1*/ /*fake_override*/ var propVar: T
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*1*/ /*fake_override*/ fun method(): T
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGB5T</*0*/ T> : IGA<T> {
+    public abstract override /*1*/ /*fake_override*/ val propVal: T
+    public abstract override /*1*/ /*fake_override*/ var propVar: T
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*1*/ /*fake_override*/ fun method(): T
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGC1 : IGB1Str, IGB2Str {
+    public abstract override /*2*/ /*fake_override*/ val propVal: kotlin.String
+    public abstract override /*2*/ /*fake_override*/ var propVar: kotlin.String
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*2*/ /*fake_override*/ fun method(): kotlin.String
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGC2 : IGB1Str, IGB3Int {
+    public abstract override /*2*/ /*fake_override*/ val propVal: kotlin.String
+    public abstract override /*2*/ /*fake_override*/ var propVar: kotlin.String
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*2*/ /*fake_override*/ fun method(): kotlin.String
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGC3</*0*/ T> : IGB4T<T>, IGB5T<T> {
+    public abstract override /*2*/ /*fake_override*/ val propVal: T
+    public abstract override /*2*/ /*fake_override*/ var propVar: T
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*2*/ /*fake_override*/ fun method(): T
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGC4</*0*/ T> : IGB4T<T>, IGB5T<kotlin.String> {
+    public abstract override /*2*/ /*fake_override*/ val propVal: T
+    public abstract override /*2*/ /*fake_override*/ var propVar: T
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*2*/ /*fake_override*/ fun method(): T
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface IGC5 : IGB4T<kotlin.String>, IGB5T<kotlin.String> {
+    public abstract override /*2*/ /*fake_override*/ val propVal: kotlin.String
+    public abstract override /*2*/ /*fake_override*/ var propVar: kotlin.String
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract override /*2*/ /*fake_override*/ fun method(): kotlin.String
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}