Refine expect classes in CliSealedClassInheritorsProvider

KT-45796 Fixed

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

@@ -18041,6 +18041,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                 public void testExpectSealedInterface() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/multiplatform/exhaustiveness/expectSealedInterface.kt");
                 }
+
+                @Test
+                @TestMetadata("kt45796.kt")
+                public void testKt45796() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/multiplatform/exhaustiveness/kt45796.kt");
+                }
             }
 
             @Nested

compiler/testData/diagnostics/tests/multiplatform/exhaustiveness/kt45796.fir.kt

@@ -0,0 +1,30 @@
+// !LANGUAGE: +MultiPlatformProjects
+// ISSUE: KT-45796
+
+// MODULE: m1-common
+expect sealed class SealedClass() {
+    class Nested : SealedClass {
+        class NestedDeeper : SealedClass
+    }
+}
+
+fun whenForExpectSealed(s: SealedClass): Int {
+    return when (s) { // should be error, because actual sealed class may add more implementations
+        is SealedClass.Nested.NestedDeeper -> 7
+        is SealedClass.Nested -> 8
+    }
+}
+
+// MODULE: m1-jvm(m1-common)
+actual sealed class SealedClass {
+    actual class Nested : SealedClass() {
+        actual class NestedDeeper : SealedClass()
+    }
+}
+
+fun whenForSealed(s: SealedClass): Int {
+    return when (s) { // Should be OK
+        is SealedClass.Nested.NestedDeeper -> 7
+        is SealedClass.Nested -> 8
+    }
+}

compiler/testData/diagnostics/tests/multiplatform/exhaustiveness/kt45796.kt

@@ -0,0 +1,30 @@
+// !LANGUAGE: +MultiPlatformProjects
+// ISSUE: KT-45796
+
+// MODULE: m1-common
+expect sealed class SealedClass() {
+    class Nested : SealedClass {
+        class NestedDeeper : SealedClass
+    }
+}
+
+fun whenForExpectSealed(s: SealedClass): Int {
+    return <!EXPECT_TYPE_IN_WHEN_WITHOUT_ELSE, NO_ELSE_IN_WHEN!>when<!> (s) { // should be error, because actual sealed class may add more implementations
+        is SealedClass.Nested.NestedDeeper -> 7
+        is SealedClass.Nested -> 8
+    }
+}
+
+// MODULE: m1-jvm(m1-common)
+actual sealed class SealedClass {
+    actual class Nested : SealedClass() {
+        actual class NestedDeeper : SealedClass()
+    }
+}
+
+fun whenForSealed(s: SealedClass): Int {
+    return when (s) { // Should be OK
+        is SealedClass.Nested.NestedDeeper -> 7
+        is SealedClass.Nested -> 8
+    }
+}

compiler/testData/diagnostics/tests/multiplatform/exhaustiveness/kt45796.txt

@@ -0,0 +1,51 @@
+// -- Module: <m1-common> --
+package
+
+public fun whenForExpectSealed(/*0*/ s: SealedClass): kotlin.Int
+
+public sealed expect class SealedClass {
+    protected constructor SealedClass()
+    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 expect class Nested : SealedClass {
+        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 expect class NestedDeeper : SealedClass {
+            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
+        }
+    }
+}
+
+// -- Module: <m1-jvm> --
+package
+
+public fun whenForExpectSealed(/*0*/ s: SealedClass): kotlin.Int
+public fun whenForSealed(/*0*/ s: SealedClass): kotlin.Int
+
+public sealed actual class SealedClass {
+    protected constructor SealedClass()
+    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 actual class Nested : SealedClass {
+        public constructor Nested()
+        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 actual class NestedDeeper : SealedClass {
+            public constructor NestedDeeper()
+            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/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -18047,6 +18047,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                 public void testExpectSealedInterface() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/multiplatform/exhaustiveness/expectSealedInterface.kt");
                 }
+
+                @Test
+                @TestMetadata("kt45796.kt")
+                public void testKt45796() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/multiplatform/exhaustiveness/kt45796.kt");
+                }
             }
 
             @Nested

core/descriptors/src/org/jetbrains/kotlin/resolve/SealedClassInheritorsProvider.kt

@@ -8,9 +8,14 @@ package org.jetbrains.kotlin.resolve
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.PackageFragmentDescriptor
+import org.jetbrains.kotlin.incremental.components.LookupLocation
+import org.jetbrains.kotlin.incremental.components.NoLookupLocation
 import org.jetbrains.kotlin.resolve.descriptorUtil.parents
 import org.jetbrains.kotlin.resolve.scopes.DescriptorKindFilter
 import org.jetbrains.kotlin.resolve.scopes.MemberScope
+import org.jetbrains.kotlin.types.checker.KotlinTypeRefiner
+import org.jetbrains.kotlin.types.refinement.TypeRefinement
+import org.jetbrains.kotlin.utils.addToStdlib.runIf
 
 abstract class SealedClassInheritorsProvider {
     /**
@@ -26,6 +31,7 @@ object CliSealedClassInheritorsProvider : SealedClassInheritorsProvider() {
     // Note this is a generic and slow implementation which would work almost for any subclass of ClassDescriptor.
     // Please avoid using it in new code.
     // TODO: do something more clever instead at call sites of this function
+    @OptIn(TypeRefinement::class)
     override fun computeSealedSubclasses(
         sealedClass: ClassDescriptor,
         allowSealedInheritorsInDifferentFilesOfSamePackage: Boolean
@@ -37,13 +43,21 @@ object CliSealedClassInheritorsProvider : SealedClassInheritorsProvider() {
         fun collectSubclasses(scope: MemberScope, collectNested: Boolean) {
             for (descriptor in scope.getContributedDescriptors(DescriptorKindFilter.CLASSIFIERS)) {
                 if (descriptor !is ClassDescriptor) continue
+                /*
+                 * scope.getContributedDescriptors() doesn't discriminate expect classes in presence
+                 *   of theirs actuals, so we need to lookup for descriptor once again via
+                 *   scope.getContributedClassifier() to match expects (if possible)
+                 */
+                val refinedDescriptor = runIf(descriptor.isExpect) {
+                    scope.getContributedClassifier(descriptor.name, NoLookupLocation.WHEN_GET_ALL_DESCRIPTORS) as? ClassDescriptor
+                } ?: descriptor
 
-                if (DescriptorUtils.isDirectSubclass(descriptor, sealedClass)) {
-                    result.add(descriptor)
+                if (DescriptorUtils.isDirectSubclass(refinedDescriptor, sealedClass)) {
+                    result.add(refinedDescriptor)
                 }
 
                 if (collectNested) {
-                    collectSubclasses(descriptor.unsubstitutedInnerClassesScope, collectNested)
+                    collectSubclasses(refinedDescriptor.unsubstitutedInnerClassesScope, collectNested)
                 }
             }
         }