Allow sealed inheritors for expect sealed classes in MPP submodules

KT-45842 Fixed
KTIJ-7068

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/SealedInheritorInSameModuleChecker.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.resolve.checkers
 
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
+import org.jetbrains.kotlin.descriptors.impl.ModuleDescriptorImpl
 import org.jetbrains.kotlin.descriptors.isSealed
 import org.jetbrains.kotlin.diagnostics.Errors
 import org.jetbrains.kotlin.psi.KtClassOrObject
@@ -22,8 +23,16 @@ object SealedInheritorInSameModuleChecker : DeclarationChecker {
             val typeReference = superTypeListEntry.typeReference ?: continue
             val superType = typeReference.getAbbreviatedTypeOrType(context.trace.bindingContext)?.unwrap() ?: continue
             val superClass = superType.constructor.declarationDescriptor ?: continue
-            if (superClass.isSealed() && superClass.module != currentModule) {
-                context.trace.report(Errors.SEALED_INHERITOR_IN_DIFFERENT_MODULE.on(typeReference))
+            if (superClass.isSealed()) {
+                /*
+                 * It's allowed to declare inheritors of expect sealed class in any dependent module until actual
+                 *   counterpart for this class will be declared. So if super class is resolved to expect sealed
+                 *   class then its allowed to declare inheritor
+                 */
+                val inheritorAllowed = superClass.isExpect || superClass.module == currentModule
+                if (!inheritorAllowed) {
+                    context.trace.report(Errors.SEALED_INHERITOR_IN_DIFFERENT_MODULE.on(typeReference))
+                }
             }
         }
     }

idea/testData/multiplatform/sealedInheritorsInComplexModuleStructure1/common/common.kt

@@ -0,0 +1,4 @@
+package foo
+
+expect sealed class <!LINE_MARKER("descr='Is subclassed by SealedWithPlatformActuals [common] SealedWithPlatformActuals [main] SimpleShared'"), LINE_MARKER("descr='Has actuals in JVM'")!>SealedWithSharedActual<!>()
+expect sealed class <!LINE_MARKER("descr='Is subclassed by SimpleShared'")!>SealedWithPlatformActuals<!> : SealedWithSharedActual

idea/testData/multiplatform/sealedInheritorsInComplexModuleStructure1/dependencies.txt

@@ -0,0 +1,6 @@
+MODULE common { platform=[JVM, JS, Native]; root=common }
+MODULE intermediate { platform=[JVM]; root=intermediate }
+MODULE main { platform=[JVM]; root=main }
+
+intermediate -> common { kind=DEPENDS_ON }
+main -> intermediate { kind=DEPENDS_ON }

idea/testData/multiplatform/sealedInheritorsInComplexModuleStructure1/intermediate/platform.kt

@@ -0,0 +1,4 @@
+package foo
+
+actual sealed class <!LINE_MARKER("descr='Is subclassed by SealedWithPlatformActuals [main] SimpleShared'"), LINE_MARKER("descr='Has declaration in common module'")!>SealedWithSharedActual<!>
+class SimpleShared : SealedWithPlatformActuals<!NO_CONSTRUCTOR!>()<!>

idea/testData/multiplatform/sealedInheritorsInComplexModuleStructure1/main/main.kt

@@ -0,0 +1,3 @@
+package foo
+
+actual sealed class SealedWithPlatformActuals <!ACTUAL_WITHOUT_EXPECT!>actual constructor()<!>: <!SEALED_INHERITOR_IN_DIFFERENT_MODULE!>SealedWithSharedActual<!>()

idea/testData/multiplatform/sealedInheritorsInComplexModuleStructure2/common/common.kt

@@ -0,0 +1,16 @@
+package foo
+
+/*
+ * - Sealed1 [common], actualized in [main]
+ *   - Sealed2 [common], actualized in [intermediate]
+ *     - Derived11 [common]
+ *     - Derived12 [intermediate]
+ *   - Derived1 [common]
+ *   - Derived2 [intermediate]
+ *   - Derived3 [main]
+ */
+expect sealed class <!LINE_MARKER("descr='Has subclasses'")!>Sealed1<!>()
+expect sealed class <!LINE_MARKER("descr='Is subclassed by Derived11 Derived12 Derived13Error'"), LINE_MARKER("descr='Has actuals in JVM'")!>Sealed2<!>() : Sealed1
+
+class Derived1 : Sealed1()
+class Derived11 : Sealed2()

idea/testData/multiplatform/sealedInheritorsInComplexModuleStructure2/dependencies.txt

@@ -0,0 +1,8 @@
+MODULE common { platform=[JVM, JS, Native]; root=common }
+MODULE intermediate { platform=[JVM]; root=intermediate }
+MODULE main { platform=[JVM]; root=main }
+MODULE real-main { platform=[JVM]; root=real-main }
+
+intermediate -> common { kind=DEPENDS_ON }
+main -> intermediate { kind=DEPENDS_ON }
+real-main -> main { kind=DEPENDS_ON }

idea/testData/multiplatform/sealedInheritorsInComplexModuleStructure2/intermediate/intermediate.kt

@@ -0,0 +1,6 @@
+package foo
+
+actual sealed class <!LINE_MARKER("descr='Is subclassed by Derived12 Derived13Error'"), LINE_MARKER("descr='Has declaration in common module'")!>Sealed2<!> : Sealed1()
+
+class Derived2 : Sealed1()
+class Derived12 : Sealed2()

idea/testData/multiplatform/sealedInheritorsInComplexModuleStructure2/main/main.kt

@@ -0,0 +1,6 @@
+package foo
+
+actual sealed class <!LINE_MARKER("descr='Is subclassed by Derived2 Derived3Error'")!>Sealed1<!> actual constructor()
+
+class Derived2 : Sealed1()
+class Derived13Error : <!SEALED_INHERITOR_IN_DIFFERENT_MODULE!>Sealed2<!>() // should be an error

idea/testData/multiplatform/sealedInheritorsInComplexModuleStructure2/real-main/real-main.kt

@@ -0,0 +1,3 @@
+package foo
+
+class Derived3Error : <!SEALED_INHERITOR_IN_DIFFERENT_MODULE!>Sealed1<!>() // should be an error

idea/testData/multiplatform/whenExhaustivenessForSealed/commonA/commonA.kt

@@ -1 +1 @@
-class CommonAImplTestClass: <!SEALED_INHERITOR_IN_DIFFERENT_MODULE!>TestClass<!>()
+class CommonAImplTestClass: TestClass()

idea/tests/org/jetbrains/kotlin/idea/caches/resolve/MultiplatformAnalysisTestGenerated.java

@@ -229,6 +229,16 @@ public class MultiplatformAnalysisTestGenerated extends AbstractMultiplatformAna
         runTest("idea/testData/multiplatform/recursiveTypes/");
     }
 
+    @TestMetadata("sealedInheritorsInComplexModuleStructure1")
+    public void testSealedInheritorsInComplexModuleStructure1() throws Exception {
+        runTest("idea/testData/multiplatform/sealedInheritorsInComplexModuleStructure1/");
+    }
+
+    @TestMetadata("sealedInheritorsInComplexModuleStructure2")
+    public void testSealedInheritorsInComplexModuleStructure2() throws Exception {
+        runTest("idea/testData/multiplatform/sealedInheritorsInComplexModuleStructure2/");
+    }
+
     @TestMetadata("simple")
     public void testSimple() throws Exception {
         runTest("idea/testData/multiplatform/simple/");