[FIR] DATA_CLASS_OVERRIDE_CONFLICT diagnostic

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt

@@ -576,6 +576,11 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
             parameter<FirCallableDeclaration<*>>("baseMember")
         }
 
+        val DATA_CLASS_OVERRIDE_CONFLICT by error<KtClassOrObject>(PositioningStrategy.DATA_MODIFIER) {
+            parameter<FirCallableDeclaration<*>>("overridingMember")
+            parameter<FirCallableDeclaration<*>>("baseMember")
+        }
+
         val CANNOT_WEAKEN_ACCESS_PRIVILEGE by error<KtModifierListOwner>(PositioningStrategy.VISIBILITY_MODIFIER) {
             parameter<Visibility>("overridingVisibility")
             parameter<FirCallableDeclaration>("overridden")

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/model/DiagnosticData.kt

@@ -74,6 +74,7 @@ enum class PositioningStrategy(private val strategy: String? = null) {
     ANNOTATION_USE_SITE,
     ASSIGNMENT_LHS,
     IMPORT_LAST_NAME,
+    DATA_MODIFIER,
 
     ;
 

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt

@@ -345,6 +345,7 @@ object FirErrors {
     // overrides
     val NOTHING_TO_OVERRIDE by error1<KtModifierListOwner, FirMemberDeclaration>(SourceElementPositioningStrategies.OVERRIDE_MODIFIER)
     val CANNOT_OVERRIDE_INVISIBLE_MEMBER by error2<KtNamedDeclaration, FirCallableDeclaration<*>, FirCallableDeclaration<*>>(SourceElementPositioningStrategies.OVERRIDE_MODIFIER)
+    val DATA_CLASS_OVERRIDE_CONFLICT by error2<KtClassOrObject, FirCallableDeclaration<*>, FirCallableDeclaration<*>>(SourceElementPositioningStrategies.DATA_MODIFIER)
     val CANNOT_WEAKEN_ACCESS_PRIVILEGE by error3<KtModifierListOwner, Visibility, FirCallableDeclaration, Name>(SourceElementPositioningStrategies.VISIBILITY_MODIFIER)
     val CANNOT_CHANGE_ACCESS_PRIVILEGE by error3<KtModifierListOwner, Visibility, FirCallableDeclaration, Name>(SourceElementPositioningStrategies.VISIBILITY_MODIFIER)
     val OVERRIDING_FINAL_MEMBER by error2<KtNamedDeclaration, FirCallableDeclaration, Name>(SourceElementPositioningStrategies.OVERRIDE_MODIFIER)

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirOverrideChecker.kt

@@ -202,6 +202,20 @@ object FirOverrideChecker : FirClassChecker() {
             }
             val kind = member.source?.kind
             // Only report if the current member has real source or it's a member property declared inside the primary constructor.
+
+            if (kind is FirFakeSourceElementKind.DataClassGeneratedMembers) {
+                overriddenMemberSymbols.find { (it.fir as? FirCallableMemberDeclaration<*>)?.isFinal == true }?.let { base ->
+                    reporter.reportOn(
+                        containingClass.source,
+                        FirErrors.DATA_CLASS_OVERRIDE_CONFLICT,
+                        member,
+                        base.fir,
+                        context
+                    )
+                }
+                return
+            }
+
             if (kind !is FirRealSourceElementKind && kind !is FirFakeSourceElementKind.PropertyFromParameter) return
 
             val overridden = overriddenMemberSymbols.first().originalOrSelf()

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDefaultErrorMessages.kt

@@ -95,6 +95,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CYCLIC_CONSTRUCTO
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CYCLIC_GENERIC_UPPER_BOUND
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CYCLIC_INHERITANCE_HIERARCHY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DATA_CLASS_NOT_PROPERTY_PARAMETER
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DATA_CLASS_OVERRIDE_CONFLICT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DATA_CLASS_VARARG_PARAMETER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DATA_CLASS_WITHOUT_PARAMETERS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DELEGATED_PROPERTY_INSIDE_INLINE_CLASS
@@ -942,6 +943,12 @@ class FirDefaultErrorMessages {
                 VIRTUAL_MEMBER_HIDDEN, "''{0}'' hides member of supertype ''{1}'' and needs ''override'' modifier", DECLARATION_NAME,
                 DECLARATION_NAME
             )
+            map.put(
+                DATA_CLASS_OVERRIDE_CONFLICT,
+                "Function ''{0}'' generated for the data class conflicts with member of supertype ''{1}''",
+                FQ_NAMES_IN_TYPES,
+                FQ_NAMES_IN_TYPES
+            )
 
             map.put(
                 GENERIC_THROWABLE_SUBCLASS,

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/LightTreePositioningStrategies.kt

@@ -354,6 +354,9 @@ object LightTreePositioningStrategies {
     val INNER_MODIFIER: LightTreePositioningStrategy =
         ModifierSetBasedLightTreePositioningStrategy(TokenSet.create(KtTokens.INNER_KEYWORD))
 
+    val DATA_MODIFIER: LightTreePositioningStrategy =
+        ModifierSetBasedLightTreePositioningStrategy(TokenSet.create(KtTokens.DATA_KEYWORD))
+
     val OPERATOR: LightTreePositioningStrategy = object : LightTreePositioningStrategy() {
         override fun mark(
             node: LighterASTNode,

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/SourceElementPositioningStrategies.kt

@@ -118,6 +118,11 @@ object SourceElementPositioningStrategies {
         PositioningStrategies.SUSPEND_MODIFIER
     )
 
+    val DATA_MODIFIER = SourceElementPositioningStrategy(
+        LightTreePositioningStrategies.DATA_MODIFIER,
+        PositioningStrategies.DATA_MODIFIER
+    )
+
     val OPERATOR = SourceElementPositioningStrategy(
         LightTreePositioningStrategies.OPERATOR,
         PositioningStrategies.OPERATOR

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/PositioningStrategies.kt

@@ -374,6 +374,9 @@ object PositioningStrategies {
     @JvmField
     val SUSPEND_MODIFIER: PositioningStrategy<KtModifierListOwner> = modifierSetPosition(KtTokens.SUSPEND_KEYWORD)
 
+    @JvmField
+    val DATA_MODIFIER: PositioningStrategy<KtModifierListOwner> = modifierSetPosition(KtTokens.DATA_KEYWORD)
+
     @JvmField
     val FOR_REDECLARATION: PositioningStrategy<PsiElement> = object : PositioningStrategy<PsiElement>() {
         override fun mark(element: PsiElement): List<TextRange> {

compiler/testData/diagnostics/tests/dataClasses/dataInheritance.fir.kt

@@ -1,13 +0,0 @@
-interface SuperInterface
-
-open class SuperClass
-
-<!INCOMPATIBLE_MODIFIERS!>abstract<!> <!INCOMPATIBLE_MODIFIERS!>data<!> class Base(val x: Int)
-
-class Derived: Base(42)
-
-data class Nasty(val z: Int, val y: Int): Base(z)
-
-data class Complex(val y: Int): SuperInterface, SuperClass()
-
-data class SubData(val sss: String) : <!FINAL_SUPERTYPE!>Complex<!>(42)

compiler/testData/diagnostics/tests/dataClasses/dataInheritance.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 interface SuperInterface
 
 open class SuperClass

compiler/testData/diagnostics/tests/dataClasses/implementTraitWhichHasFinalComponent1.fir.kt

@@ -2,4 +2,4 @@ interface T {
     final fun component1(): Int = 42
 }
 
-data class A(val x: Int) : T
+<!DATA_CLASS_OVERRIDE_CONFLICT!>data<!> class A(val x: Int) : T

compiler/testData/diagnostics/tests/explicitDefinitelyNotNull/overrides.fir.kt

@@ -5,10 +5,10 @@ interface A<T> {
     fun bar(x: T!!): T!!
 }
 
-//interface B<T1> : A<T1> {
-//    override fun foo(x: T1): T1
-//    override fun bar(x: T1!!): T1!!
-//}
+interface B<T1> : A<T1> {
+    override fun foo(x: T1): T1
+    override fun bar(x: T1!!): T1!!
+}
 
 interface C<T2> : A<T2> {
     override fun foo(x: T2!!): T2!!

compiler/testData/diagnostics/tests/multimodule/duplicateSuper/sameSuperTraitDifferentBounds.fir.kt

@@ -1,4 +1,3 @@
-// fir reports NOTHING_TO_OVERRIDE because it keeps only one definition of p.Base
 // MODULE: m1
 // FILE: x.kt
 package p

compiler/testData/diagnostics/tests/sourceCompatibility/noDataClassInheritance.fir.kt

@@ -8,7 +8,7 @@ open class NotAllowed
 
 class Derived: Base(42)
 
-data class Nasty(val z: Int, val y: Int): Base(z)
+<!DATA_CLASS_OVERRIDE_CONFLICT!>data<!> class Nasty(val z: Int, val y: Int): Base(z)
 
 data class Complex(val y: Int): Allowed, NotAllowed()