[FIR] Properly check for visibility in FirTypeIntersectionScopeContext

This fixes a false positive OVERRIDING_FINAL_MEMBER caused by a
package-private member in a different package being added to the
list of overridden symbols. However, in Java, package-private members
from different packages are effectively like private members in that
they cannot be overridden.

#KT-61696 Fixed

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java

@@ -24825,6 +24825,12 @@ public class DiagnosticCompilerTestFE10TestdataTestGenerated extends AbstractDia
                     runTest("compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt9550.kt");
                 }
 
+                @Test
+                @TestMetadata("packagePrivateAndPublic.kt")
+                public void testPackagePrivateAndPublic() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/override/clashesOnInheritance/packagePrivateAndPublic.kt");
+                }
+
                 @Test
                 @TestMetadata("returnTypeMismatch.kt")
                 public void testReturnTypeMismatch() throws Exception {

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java

@@ -24825,6 +24825,12 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated
                     runTest("compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt9550.kt");
                 }
 
+                @Test
+                @TestMetadata("packagePrivateAndPublic.kt")
+                public void testPackagePrivateAndPublic() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/override/clashesOnInheritance/packagePrivateAndPublic.kt");
+                }
+
                 @Test
                 @TestMetadata("returnTypeMismatch.kt")
                 public void testReturnTypeMismatch() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirLightTreeOldFrontendDiagnosticsTestGenerated.java

@@ -24825,6 +24825,12 @@ public class FirLightTreeOldFrontendDiagnosticsTestGenerated extends AbstractFir
                     runTest("compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt9550.kt");
                 }
 
+                @Test
+                @TestMetadata("packagePrivateAndPublic.kt")
+                public void testPackagePrivateAndPublic() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/override/clashesOnInheritance/packagePrivateAndPublic.kt");
+                }
+
                 @Test
                 @TestMetadata("returnTypeMismatch.kt")
                 public void testReturnTypeMismatch() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirPsiOldFrontendDiagnosticsTestGenerated.java

@@ -24831,6 +24831,12 @@ public class FirPsiOldFrontendDiagnosticsTestGenerated extends AbstractFirPsiDia
                     runTest("compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt9550.kt");
                 }
 
+                @Test
+                @TestMetadata("packagePrivateAndPublic.kt")
+                public void testPackagePrivateAndPublic() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/override/clashesOnInheritance/packagePrivateAndPublic.kt");
+                }
+
                 @Test
                 @TestMetadata("returnTypeMismatch.kt")
                 public void testReturnTypeMismatch() throws Exception {

compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/session/FirNativeSessionFactory.kt

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.library.metadata.resolver.KotlinResolvedLibrary
 import org.jetbrains.kotlin.name.Name
 
 object FirNativeSessionFactory : FirAbstractSessionFactory() {
+    @OptIn(SessionConfiguration::class)
     fun createLibrarySession(
         mainModuleName: Name,
         resolvedLibraries: List<KotlinResolvedLibrary>,
@@ -39,6 +40,7 @@ object FirNativeSessionFactory : FirAbstractSessionFactory() {
             languageVersionSettings,
             extensionRegistrars,
             registerExtraComponents = { session ->
+                session.register(FirVisibilityChecker::class, FirVisibilityChecker.Default)
                 registerExtraComponents(session)
             },
             createKotlinScopeProvider = { FirKotlinScopeProvider() },

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/FirJavaVisibilityChecker.kt

@@ -18,7 +18,6 @@ import org.jetbrains.kotlin.fir.declarations.utils.visibility
 import org.jetbrains.kotlin.fir.expressions.FirExpression
 import org.jetbrains.kotlin.fir.resolve.SupertypeSupplier
 import org.jetbrains.kotlin.fir.resolve.calls.FirSimpleSyntheticPropertySymbol
-import org.jetbrains.kotlin.fir.resolve.calls.ReceiverValue
 import org.jetbrains.kotlin.fir.resolve.isSubclassOf
 import org.jetbrains.kotlin.fir.symbols.FirBasedSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
@@ -76,12 +75,12 @@ object FirJavaVisibilityChecker : FirVisibilityChecker() {
     }
 
     override fun platformOverrideVisibilityCheck(
-        candidateInDerivedClass: FirBasedSymbol<*>,
+        packageNameOfDerivedClass: FqName,
         symbolInBaseClass: FirBasedSymbol<*>,
         visibilityInBaseClass: Visibility,
     ): Boolean = when (visibilityInBaseClass) {
         JavaVisibilities.ProtectedAndPackage, JavaVisibilities.ProtectedStaticVisibility -> true
-        JavaVisibilities.PackageVisibility -> symbolInBaseClass.isInPackage(candidateInDerivedClass.packageFqName())
+        JavaVisibilities.PackageVisibility -> symbolInBaseClass.isInPackage(packageNameOfDerivedClass)
         else -> true
     }
 

compiler/fir/providers/src/org/jetbrains/kotlin/fir/FirVisibilityChecker.kt

@@ -68,7 +68,7 @@ abstract class FirVisibilityChecker : FirSessionComponent {
         }
 
         override fun platformOverrideVisibilityCheck(
-            candidateInDerivedClass: FirBasedSymbol<*>,
+            packageNameOfDerivedClass: FqName,
             symbolInBaseClass: FirBasedSymbol<*>,
             visibilityInBaseClass: Visibility,
         ): Boolean {
@@ -151,13 +151,20 @@ abstract class FirVisibilityChecker : FirSessionComponent {
 
     fun isVisibleForOverriding(
         candidateInDerivedClass: FirMemberDeclaration,
-        candidateInBaseClass: FirMemberDeclaration
+        candidateInBaseClass: FirMemberDeclaration,
-    ): Boolean = isVisibleForOverriding(candidateInDerivedClass.moduleData, candidateInDerivedClass.symbol, candidateInBaseClass)
+    ): Boolean =
+        isVisibleForOverriding(candidateInDerivedClass.moduleData, candidateInDerivedClass.symbol.packageFqName(), candidateInBaseClass)
 
     fun isVisibleForOverriding(
         derivedClassModuleData: FirModuleData,
         symbolFromDerivedClass: FirBasedSymbol<*>,
         candidateInBaseClass: FirMemberDeclaration,
+    ): Boolean = isVisibleForOverriding(derivedClassModuleData, symbolFromDerivedClass.packageFqName(), candidateInBaseClass)
+
+    fun isVisibleForOverriding(
+        derivedClassModuleData: FirModuleData,
+        packageNameOfDerivedClass: FqName,
+        candidateInBaseClass: FirMemberDeclaration,
     ): Boolean = when (candidateInBaseClass.visibility) {
         Visibilities.Internal -> {
             candidateInBaseClass.moduleData == derivedClassModuleData ||
@@ -166,7 +173,14 @@ abstract class FirVisibilityChecker : FirSessionComponent {
 
         Visibilities.Private, Visibilities.PrivateToThis -> false
         Visibilities.Protected -> true
-        else -> platformOverrideVisibilityCheck(symbolFromDerivedClass, candidateInBaseClass.symbol, candidateInBaseClass.visibility)
+        else -> {
+
+            platformOverrideVisibilityCheck(
+                packageNameOfDerivedClass,
+                candidateInBaseClass.symbol,
+                candidateInBaseClass.visibility
+            )
+        }
     }
 
     private fun isSpecificDeclarationVisible(
@@ -249,7 +263,7 @@ abstract class FirVisibilityChecker : FirSessionComponent {
     ): Boolean
 
     protected abstract fun platformOverrideVisibilityCheck(
-        candidateInDerivedClass: FirBasedSymbol<*>,
+        packageNameOfDerivedClass: FqName,
         symbolInBaseClass: FirBasedSymbol<*>,
         visibilityInBaseClass: Visibility,
     ): Boolean

compiler/fir/providers/src/org/jetbrains/kotlin/fir/scopes/impl/FirTypeIntersectionScopeContext.kt

@@ -39,7 +39,8 @@ class FirTypeIntersectionScopeContext(
 ) {
     private val overrideService = session.overrideService
 
-    private val isReceiverClassExpect = dispatchReceiverType.toRegularClassSymbol(session)?.isExpect == true
+    private val dispatchClassSymbol: FirRegularClassSymbol? = dispatchReceiverType.toRegularClassSymbol(session)
+    private val isReceiverClassExpect = dispatchClassSymbol?.isExpect == true
 
     val intersectionOverrides: FirCache<FirCallableSymbol<*>, MemberWithBaseScope<FirCallableSymbol<*>>, ResultOfIntersection.NonTrivial<*>> =
         session.intersectionOverrideStorage.cacheByScope.getValue(dispatchReceiverType)
@@ -150,9 +151,9 @@ class FirTypeIntersectionScopeContext(
         val result = mutableListOf<ResultOfIntersection<D>>()
 
         while (allMembersWithScope.size > 1) {
-            val groupWithPrivate =
+            val groupWithInvisible =
                 overrideService.extractBothWaysOverridable(allMembersWithScope.maxByVisibility(), allMembersWithScope, overrideChecker)
-            val group = groupWithPrivate.filter { !Visibilities.isPrivate(it.member.fir.visibility) }.ifEmpty { groupWithPrivate }
+            val group = groupWithInvisible.filter { it.isVisible() }.ifEmpty { groupWithInvisible }
             val nonSubsumed = if (forClassUseSiteScope) group.nonSubsumed() else group
             val mostSpecific = overrideService.selectMostSpecificMembers(nonSubsumed, ReturnTypeCalculatorForFullBodyResolve.Default)
             val nonTrivial = if (forClassUseSiteScope) {
@@ -186,6 +187,17 @@ class FirTypeIntersectionScopeContext(
         return result
     }
 
+    private fun MemberWithBaseScope<*>.isVisible(): Boolean {
+        // Checking for private is not enough because package-private declarations can be hidden, too, if they're in a different package.
+        val dispatchClassSymbol = dispatchClassSymbol ?: return true
+
+        return session.visibilityChecker.isVisibleForOverriding(
+            dispatchClassSymbol.moduleData,
+            dispatchClassSymbol.classId.packageFqName,
+            member.fir
+        )
+    }
+
     fun <D : FirCallableSymbol<*>> createIntersectionOverride(
         mostSpecific: List<MemberWithBaseScope<D>>,
         extractedOverrides: List<MemberWithBaseScope<D>>,

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

@@ -0,0 +1,29 @@
+// FIR_IDENTICAL
+// FILE: ViewModel.java
+package viewmodel;
+
+public class ViewModel {
+    final void clear() {
+    }
+}
+
+// FILE: samePackage.kt
+package viewmodel
+
+interface IMyViewModel {
+    fun clear()
+}
+
+class MyViewModel: ViewModel(), IMyViewModel {
+    <!OVERRIDING_FINAL_MEMBER!>override<!> fun clear() = Unit
+}
+
+// FILE: differentPackage.kt
+package different
+
+import viewmodel.IMyViewModel
+import viewmodel.ViewModel
+
+class MyViewModel: ViewModel(), IMyViewModel {
+    override fun clear() = Unit
+}

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -26571,6 +26571,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                     runTest("compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt9550.kt");
                 }
 
+                @Test
+                @TestMetadata("packagePrivateAndPublic.kt")
+                public void testPackagePrivateAndPublic() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/override/clashesOnInheritance/packagePrivateAndPublic.kt");
+                }
+
                 @Test
                 @TestMetadata("returnTypeMismatch.kt")
                 public void testReturnTypeMismatch() throws Exception {