[FIR] Implement RETURN_TYPE_MISMATCH_ON_INHERITANCE diagnostic

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

@@ -1,37 +0,0 @@
-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
-<!ABSTRACT_MEMBER_NOT_IMPLEMENTED!>class CDerivedInvalid1<!> : ILeft, IRight
-
-// Error: CLeft::copy and IRight::copy have unrelated return types
-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.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 interface IBase {
     fun copy(): IBase
 }

compiler/testData/diagnostics/tests/override/clashesOnInheritance/flexibleReturnTypeList.fir.kt

@@ -1,43 +0,0 @@
-// FILE: J.java
-public interface J {
-    java.util.List<String> foo();
-}
-
-// FILE: K.kt
-interface ILNS {
-    fun foo(): List<String?>
-}
-
-interface IMLS {
-    fun foo(): MutableList<String>
-}
-
-interface IMLNS {
-    fun foo(): MutableList<String?>
-}
-
-interface ILS {
-    fun foo(): List<String>
-}
-
-interface Test1 : ILNS, J
-interface Test2 : J, ILNS
-
-interface Test3 : IMLS, J
-interface Test4 : J, IMLS
-
-interface Test5 : ILNS, IMLS, J
-interface Test6 : ILNS, J, IMLS
-interface Test7 : J, ILNS, IMLS
-
-// Return types of ILS::foo and IMLNS::foo are incompatible themselves.
-// However, return type of J::foo is (Mutable)List<String!>!,
-// which is subtype of both List<String> and MutalbeList<String?>.
-// Thus, inheriting from J, IMLNS, and ILS is Ok,
-// but inheriting from IMLNS and ILS is not.
-
-interface Test8 : J, IMLNS, ILS
-interface Test9 : IMLNS, J, ILS
-interface Test10 : IMLNS, ILS, J
-
-interface Test11 : IMLNS, ILS

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

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // FILE: J.java
 public interface J {
     java.util.List<String> foo();

compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt13355viaJava.fir.kt

@@ -1,47 +0,0 @@
-// FILE: K.kt
-abstract class ATest1 : TestNN.JNullVsNotNull()
-
-abstract class ATest2 : TestNN.JUnknownImpl(), TestNN.JNotNull
-
-abstract class ATest3 : TestNN.JUnknownVsNotNull()
-
-class CTest1 : TestNN.JNullVsNotNull()
-
-class CTest2 : TestNN.JUnknownImpl(), TestNN.JNotNull
-
-class CTest3 : TestNN.JUnknownVsNotNull()
-
-// FILE: TestNN.java
-import org.jetbrains.annotations.*;
-
-public class TestNN {
-    public interface JNull {
-        @Nullable Object foo();
-    }
-
-    public interface JNotNull {
-        @NotNull Object foo();
-    }
-
-    public static class JNullVsNotNull implements JNull, JNotNull {
-        public Object foo() {
-            return this;
-        }
-    }
-
-    public static class JNullBase {
-        @Nullable public Object foo() {
-            return null;
-        }
-    }
-
-    public static class JUnknownImpl extends JNullBase {
-        public Object foo() {
-            return this;
-        }
-    }
-
-    public static class JUnknownVsNotNull extends JUnknownImpl implements JNotNull {
-    }
-}
-

compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt13355viaJava.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // FILE: K.kt
 abstract class ATest1 : TestNN.JNullVsNotNull()
 

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

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

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

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 open class A {
     open fun foo(): Boolean = true
 }