FIR: introduce delegated & overridden conflict checks

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

@@ -336,6 +336,14 @@ object DIAGNOSTICS_LIST : DiagnosticList() {
             parameter<FirClass<*>>("classOrObject")
             parameter<FirCallableDeclaration<*>>("missingDeclaration")
         }
+        val OVERRIDING_FINAL_MEMBER_BY_DELEGATION by error<FirSourceElement, KtClassOrObject>(PositioningStrategy.DECLARATION_NAME) {
+            parameter<FirCallableDeclaration<*>>("delegatedDeclaration")
+            parameter<FirCallableDeclaration<*>>("overriddenDeclaration")
+        }
+        val DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE by warning<FirSourceElement, KtClassOrObject>(PositioningStrategy.DECLARATION_NAME) {
+            parameter<FirCallableDeclaration<*>>("delegatedDeclaration")
+            parameter<FirCallableDeclaration<*>>("overriddenDeclaration")
+        }
 
         val RETURN_TYPE_MISMATCH_ON_OVERRIDE by error<FirSourceElement, KtNamedDeclaration>(PositioningStrategy.DECLARATION_RETURN_TYPE) {
             parameter<FirMemberDeclaration>("function")

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

@@ -225,6 +225,8 @@ object FirErrors {
     val INVISIBLE_ABSTRACT_MEMBER_FROM_SUPER_WARNING by warning2<FirSourceElement, KtClassOrObject, FirClass<*>, FirCallableDeclaration<*>>(SourceElementPositioningStrategies.DECLARATION_NAME)
     val MANY_IMPL_MEMBER_NOT_IMPLEMENTED by error2<FirSourceElement, KtClassOrObject, FirClass<*>, FirCallableDeclaration<*>>(SourceElementPositioningStrategies.DECLARATION_NAME)
     val MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED by error2<FirSourceElement, KtClassOrObject, FirClass<*>, FirCallableDeclaration<*>>(SourceElementPositioningStrategies.DECLARATION_NAME)
+    val OVERRIDING_FINAL_MEMBER_BY_DELEGATION by error2<FirSourceElement, KtClassOrObject, FirCallableDeclaration<*>, FirCallableDeclaration<*>>(SourceElementPositioningStrategies.DECLARATION_NAME)
+    val DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE by warning2<FirSourceElement, KtClassOrObject, FirCallableDeclaration<*>, FirCallableDeclaration<*>>(SourceElementPositioningStrategies.DECLARATION_NAME)
     val RETURN_TYPE_MISMATCH_ON_OVERRIDE by error2<FirSourceElement, KtNamedDeclaration, FirMemberDeclaration, FirMemberDeclaration>(SourceElementPositioningStrategies.DECLARATION_RETURN_TYPE)
     val PROPERTY_TYPE_MISMATCH_ON_OVERRIDE by error2<FirSourceElement, KtNamedDeclaration, FirMemberDeclaration, FirMemberDeclaration>(SourceElementPositioningStrategies.DECLARATION_RETURN_TYPE)
     val VAR_TYPE_MISMATCH_ON_OVERRIDE by error2<FirSourceElement, KtNamedDeclaration, FirMemberDeclaration, FirMemberDeclaration>(SourceElementPositioningStrategies.DECLARATION_RETURN_TYPE)

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

@@ -18,10 +18,12 @@ import org.jetbrains.kotlin.fir.analysis.checkers.unsubstitutedScope
 import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ABSTRACT_CLASS_MEMBER_NOT_IMPLEMENTED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ABSTRACT_MEMBER_NOT_IMPLEMENTED
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.INVISIBLE_ABSTRACT_MEMBER_FROM_SUPER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.INVISIBLE_ABSTRACT_MEMBER_FROM_SUPER_WARNING
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MANY_IMPL_MEMBER_NOT_IMPLEMENTED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.OVERRIDING_FINAL_MEMBER_BY_DELEGATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.reportOn
 import org.jetbrains.kotlin.fir.containingClass
 import org.jetbrains.kotlin.fir.declarations.*
@@ -135,16 +137,58 @@ object FirNotImplementedOverrideChecker : FirClassChecker() {
             }
         }
         if (notImplementedIntersectionSymbols.isNotEmpty()) {
-            val notImplementedIntersectionSymbol = notImplementedIntersectionSymbols.first()
+            var overridingFinalByDelegationReported = false
-            val notImplementedIntersection = notImplementedIntersectionSymbol.fir
+            var manyMemberNotImplementedReported = false
-            val intersections = (notImplementedIntersectionSymbol as FirIntersectionCallableSymbol).intersections
+            var delegatedHidesSupertypeReported = false
-            if (intersections.any {
+            for (notImplementedIntersectionSymbol in notImplementedIntersectionSymbols) {
-                    (it.containingClass()?.toSymbol(context.session)?.fir as? FirRegularClass)?.classKind == ClassKind.CLASS
+                val notImplementedIntersection = notImplementedIntersectionSymbol.fir
+                val intersections = (notImplementedIntersectionSymbol as FirIntersectionCallableSymbol).intersections
+                val delegatedIntersected = intersections.find {
+                    val fir = it.fir as FirCallableMemberDeclaration
+                    fir.origin == FirDeclarationOrigin.Delegated
                 }
-            ) {
+                if (delegatedIntersected != null) {
-                reporter.reportOn(source, MANY_IMPL_MEMBER_NOT_IMPLEMENTED, declaration, notImplementedIntersection, context)
+                    val finalIntersected = intersections.find { (it.fir as FirCallableMemberDeclaration).modality == Modality.FINAL }
-            } else {
+                    if (finalIntersected != null) {
-                reporter.reportOn(source, MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED, declaration, notImplementedIntersection, context)
+                        if (!overridingFinalByDelegationReported) {
+                            reporter.reportOn(
+                                source,
+                                OVERRIDING_FINAL_MEMBER_BY_DELEGATION,
+                                delegatedIntersected.fir,
+                                finalIntersected.fir,
+                                context
+                            )
+                            overridingFinalByDelegationReported = true
+                        }
+                        continue
+                    }
+                    val notDelegatedIntersected = intersections.firstOrNull {
+                        (it.fir as FirCallableMemberDeclaration).origin != FirDeclarationOrigin.Delegated
+                    }
+                    if (notDelegatedIntersected != null) {
+                        if (!delegatedHidesSupertypeReported) {
+                            reporter.reportOn(
+                                source,
+                                DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE,
+                                delegatedIntersected.fir,
+                                notDelegatedIntersected.fir,
+                                context
+                            )
+                            delegatedHidesSupertypeReported = true
+                        }
+                        continue
+                    }
+                }
+                if (manyMemberNotImplementedReported) continue
+                if (intersections.any {
+                        (it.containingClass()?.toSymbol(context.session)?.fir as? FirRegularClass)?.classKind == ClassKind.CLASS
+                    }
+                ) {
+                    reporter.reportOn(source, MANY_IMPL_MEMBER_NOT_IMPLEMENTED, declaration, notImplementedIntersection, context)
+                } else {
+                    reporter.reportOn(source, MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED, declaration, notImplementedIntersection, context)
+                }
+                manyMemberNotImplementedReported = true
             }
         }
     }

compiler/testData/diagnostics/tests/delegation/clashes/finalMemberOverridden.fir.kt

@@ -39,18 +39,18 @@ class CBarT<T> : IBarT<T> {
     override val bar: T get() = null!!
 }
 
-class Test1 : Final(), IFoo by CFoo()
+<!OVERRIDING_FINAL_MEMBER_BY_DELEGATION!>class Test1<!> : Final(), IFoo by CFoo()
 
-class Test2 : Final(), IBar by CBar()
+<!OVERRIDING_FINAL_MEMBER_BY_DELEGATION!>class Test2<!> : Final(), IBar by CBar()
 
-class Test3 : Final(), IQux by CQux()
+<!OVERRIDING_FINAL_MEMBER_BY_DELEGATION!>class Test3<!> : Final(), IQux by CQux()
 
-class Test4 : Derived(), IFoo by CFoo()
+<!OVERRIDING_FINAL_MEMBER_BY_DELEGATION!>class Test4<!> : Derived(), IFoo by CFoo()
 
-class Test5 : Derived(), IBar by CBar()
+<!OVERRIDING_FINAL_MEMBER_BY_DELEGATION!>class Test5<!> : Derived(), IBar by CBar()
 
-class Test6 : Derived(), IQux by CQux()
+<!OVERRIDING_FINAL_MEMBER_BY_DELEGATION!>class Test6<!> : Derived(), IQux by CQux()
 
-class Test7 : Final(), IBarT<Int> by CBarT<Int>()
+<!OVERRIDING_FINAL_MEMBER_BY_DELEGATION!>class Test7<!> : Final(), IBarT<Int> by CBarT<Int>()
 
-class Test8 : Final(), IBarT<Int> by CBar()
+<!OVERRIDING_FINAL_MEMBER_BY_DELEGATION!>class Test8<!> : Final(), IBarT<Int> by CBar()

compiler/testData/diagnostics/tests/delegation/covariantOverrides/fromClass.fir.kt

@@ -6,7 +6,7 @@ open class IDerived1 : IBase1 {
     override fun foo(): String = "1"
 }
 
-class Broken1(val b: IBase1) : IBase1 by b, IDerived1()
+<!DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE!>class Broken1<!>(val b: IBase1) : IBase1 by b, IDerived1()
 
 interface IBase2 {
     val foo: Any
@@ -16,4 +16,4 @@ open class IDerived2 : IBase2 {
     override val foo: String = "2"
 }
 
-class Broken2(val b: IBase2) : IBase2 by b, IDerived2()
+<!DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE!>class Broken2<!>(val b: IBase2) : IBase2 by b, IDerived2()

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeWithOverride.fir.kt

@@ -1,19 +0,0 @@
-public interface Base {
-    fun test() = "OK"
-}
-
-public interface Base2 : Base {
-    override fun test() = "OK2"
-}
-
-class Delegate : Base2
-
-fun box(): String {
-    object : Base, Base2 by Delegate() {
-    }
-
-    object : Base2, Base by Delegate() {
-    }
-
-    return "OK"
-}

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeWithOverride.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 public interface Base {
     fun test() = "OK"
 }

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeWithOverrideProperty.fir.kt

@@ -1,26 +0,0 @@
-public interface Base {
-    var test: String
-        get() = "OK"
-        set(s: String) {
-        }
-}
-
-public interface Base2 : Base {
-    override var test: String
-            get() = "OK2"
-            set(value) {}
-}
-
-class Delegate : Base2 {
-
-}
-
-fun box(): String {
-    object : Base, Base2 by Delegate() {
-    }
-
-    object : Base2, Base by Delegate() {
-    }
-
-    return "OK"
-}

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeWithOverrideProperty.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 public interface Base {
     var test: String
         get() = "OK"

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/diamond.fir.kt

@@ -23,19 +23,19 @@ class ImplAll : Base, Base2, Base3 {
 }
 
 fun box(): String {
-    object : Base2, Base3, Base by Impl() {
+    <!DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE!>object<!> : Base2, Base3, Base by Impl() {
 
     }
 
-    object : Base2 by Impl2(), Base3, Base {
+    <!DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE!>object<!> : Base2 by Impl2(), Base3, Base {
 
     }
 
-    object : Base2, Base3 by Impl3(), Base {
+    <!DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE!>object<!> : Base2, Base3 by Impl3(), Base {
 
     }
 
-    object : Base2 by Impl2(), Base3 by Impl3(), Base by Impl() {
+    <!MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED!>object<!> : Base2 by Impl2(), Base3 by Impl3(), Base by Impl() {
 
     }
 

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/fakeOverrideInTheMiddle.fir.kt

@@ -1,13 +0,0 @@
-interface Base {
-    fun test() = "Base"
-}
-
-class Delegate : Base
-
-abstract class Middle : Base {
-    override fun test() = "MyClass"
-}
-
-abstract class MyClass : Middle()
-
-class A : MyClass(), Base by Delegate()

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/fakeOverrideInTheMiddle.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 interface Base {
     fun test() = "Base"
 }

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/sameDelegationInHierarchy2.fir.kt

@@ -14,7 +14,7 @@ class Delegate : Derived {
 public open class MyClass : Base by Delegate()
 
 fun box(): String {
-    object : MyClass(), Derived by Delegate() {
+    <!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>object<!> : MyClass(), Derived by Delegate() {
     }
     return "OK"
 }

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/severalDelegates.fir.kt

@@ -23,6 +23,6 @@ public abstract class MyClass : Base1, Base2 {
     }
 }
 
-class A : MyClass(), Base1 by Delegate1(), Base1 by Delegate2() {
+<!DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE!>class A<!> : MyClass(), Base1 by Delegate1(), Base1 by Delegate2() {
 
 }

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simple.fir.kt

@@ -1,19 +0,0 @@
-public interface Base {
-    fun getValue(): String
-
-    fun test() = getValue()
-}
-
-class Delegate : Base {
-    override fun getValue() = "Delegate"
-}
-
-public abstract class MyClass : Base {
-    override fun test(): String {
-        return "Class"
-    }
-}
-
-class A : MyClass(), Base by Delegate() {
-    override fun getValue() = "Delegate"
-}

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simple.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 public interface Base {
     fun getValue(): String
 

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simpleProp.fir.kt

@@ -1,17 +0,0 @@
-public interface Base {
-    val test: String
-        get() = "OK"
-}
-
-open class Delegate : Base {
-    override val test: String
-        get() = "OK"
-}
-
-fun box(): String {
-    object : Delegate(), Base by Delegate() {
-
-    }
-
-    return "OK"
-}

compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simpleProp.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 public interface Base {
     val test: String
         get() = "OK"

compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/superTraitAndDelegationToTraitImpl.fir.kt

@@ -10,4 +10,4 @@ interface B {
 
 class C(f: A<String>): A<String> by f, B
 
-class D(f: A<Int>): A<Int> by f, B
+<!DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE!>class D<!>(f: A<Int>): A<Int> by f, B

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt

@@ -965,6 +965,22 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.OVERRIDING_FINAL_MEMBER_BY_DELEGATION) { firDiagnostic ->
+        OverridingFinalMemberByDelegationImpl(
+            firSymbolBuilder.callableBuilder.buildCallableSymbol(firDiagnostic.a as FirCallableDeclaration),
+            firSymbolBuilder.callableBuilder.buildCallableSymbol(firDiagnostic.b as FirCallableDeclaration),
+            firDiagnostic as FirPsiDiagnostic<*>,
+            token,
+        )
+    }
+    add(FirErrors.DELEGATED_MEMBER_HIDES_SUPERTYPE_OVERRIDE) { firDiagnostic ->
+        DelegatedMemberHidesSupertypeOverrideImpl(
+            firSymbolBuilder.callableBuilder.buildCallableSymbol(firDiagnostic.a as FirCallableDeclaration),
+            firSymbolBuilder.callableBuilder.buildCallableSymbol(firDiagnostic.b as FirCallableDeclaration),
+            firDiagnostic as FirPsiDiagnostic<*>,
+            token,
+        )
+    }
     add(FirErrors.RETURN_TYPE_MISMATCH_ON_OVERRIDE) { firDiagnostic ->
         ReturnTypeMismatchOnOverrideImpl(
             firSymbolBuilder.buildSymbol(firDiagnostic.a as FirDeclaration),

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt

@@ -690,6 +690,18 @@ sealed class KtFirDiagnostic<PSI: PsiElement> : KtDiagnosticWithPsi<PSI> {
         abstract val missingDeclaration: KtCallableSymbol
     }
 
+    abstract class OverridingFinalMemberByDelegation : KtFirDiagnostic<KtClassOrObject>() {
+        override val diagnosticClass get() = OverridingFinalMemberByDelegation::class
+        abstract val delegatedDeclaration: KtCallableSymbol
+        abstract val overriddenDeclaration: KtCallableSymbol
+    }
+
+    abstract class DelegatedMemberHidesSupertypeOverride : KtFirDiagnostic<KtClassOrObject>() {
+        override val diagnosticClass get() = DelegatedMemberHidesSupertypeOverride::class
+        abstract val delegatedDeclaration: KtCallableSymbol
+        abstract val overriddenDeclaration: KtCallableSymbol
+    }
+
     abstract class ReturnTypeMismatchOnOverride : KtFirDiagnostic<KtNamedDeclaration>() {
         override val diagnosticClass get() = ReturnTypeMismatchOnOverride::class
         abstract val function: KtSymbol

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt

@@ -1105,6 +1105,24 @@ internal class ManyInterfacesMemberNotImplementedImpl(
     override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
 }
 
+internal class OverridingFinalMemberByDelegationImpl(
+    override val delegatedDeclaration: KtCallableSymbol,
+    override val overriddenDeclaration: KtCallableSymbol,
+    firDiagnostic: FirPsiDiagnostic<*>,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.OverridingFinalMemberByDelegation(), KtAbstractFirDiagnostic<KtClassOrObject> {
+    override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
+}
+
+internal class DelegatedMemberHidesSupertypeOverrideImpl(
+    override val delegatedDeclaration: KtCallableSymbol,
+    override val overriddenDeclaration: KtCallableSymbol,
+    firDiagnostic: FirPsiDiagnostic<*>,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.DelegatedMemberHidesSupertypeOverride(), KtAbstractFirDiagnostic<KtClassOrObject> {
+    override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
+}
+
 internal class ReturnTypeMismatchOnOverrideImpl(
     override val function: KtSymbol,
     override val superFunction: KtSymbol,