Recompile all sealed class usages when new derived class is added

jps-plugin/src/org/jetbrains/kotlin/jps/incremental/protoDifferenceUtils.kt

@@ -177,6 +177,7 @@ private class DifferenceCalculatorForClass(oldData: ProtoMapValue, newData: Prot
     override fun difference(): Difference {
         var isClassSignatureChanged = false
         val names = hashSetOf<String>()
+        val classIsSealed = newProto.isSealed && oldProto.isSealed
 
         fun Int.oldToNames() = names.add(oldNameResolver.getString(this))
         fun Int.newToNames() = names.add(newNameResolver.getString(this))
@@ -193,8 +194,15 @@ private class DifferenceCalculatorForClass(oldData: ProtoMapValue, newData: Prot
                     if (oldProto.hasCompanionObjectName()) oldProto.companionObjectName.oldToNames()
                     if (newProto.hasCompanionObjectName()) newProto.companionObjectName.newToNames()
                 }
-                ProtoBufClassKind.NESTED_CLASS_NAME_LIST ->
+                ProtoBufClassKind.NESTED_CLASS_NAME_LIST -> {
+                    if (classIsSealed) {
+                        // when class is sealed, adding an implementation can break exhaustive when expressions
+                        // the workaround is to recompile all class usages
+                        isClassSignatureChanged = true
+                    }
+
                     names.addAll(calcDifferenceForNames(oldProto.nestedClassNameList, newProto.nestedClassNameList))
+                }
                 ProtoBufClassKind.CONSTRUCTOR_LIST ->
                     names.addAll(calcDifferenceForNonPrivateMembers(ProtoBuf.Class::getConstructorList))
                 ProtoBufClassKind.FUNCTION_LIST ->
@@ -255,3 +263,6 @@ private class DifferenceCalculatorForPackageFacade(oldData: ProtoMapValue, newDa
         return Difference(isClassSignatureChanged = false, changedMembersNames = names)
     }
 }
+
+private val ProtoBuf.Class.isSealed: Boolean
+    get() = ProtoBuf.Modality.SEALED == Flags.MODALITY.get(flags)

jps-plugin/test/org/jetbrains/kotlin/jps/build/ExperimentalIncrementalJpsTestGenerated.java

@@ -1159,6 +1159,12 @@ public class ExperimentalIncrementalJpsTestGenerated extends AbstractExperimenta
             doTest(fileName);
         }
 
+        @TestMetadata("sealedClassImplAdded")
+        public void testSealedClassImplAdded() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("jps-plugin/testData/incremental/classHierarchyAffected/sealedClassImplAdded/");
+            doTest(fileName);
+        }
+
         @TestMetadata("starProjectionUpperBoundChanged")
         public void testStarProjectionUpperBoundChanged() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("jps-plugin/testData/incremental/classHierarchyAffected/starProjectionUpperBoundChanged/");

jps-plugin/test/org/jetbrains/kotlin/jps/incremental/ProtoComparisonTestGenerated.java

@@ -159,6 +159,12 @@ public class ProtoComparisonTestGenerated extends AbstractProtoComparisonTest {
             doTest(fileName);
         }
 
+        @TestMetadata("sealedClassImplAdded")
+        public void testSealedClassImplAdded() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("jps-plugin/testData/comparison/classMembersOnlyChanged/sealedClassImplAdded/");
+            doTest(fileName);
+        }
+
     }
 
     @TestMetadata("jps-plugin/testData/comparison/packageMembers")

jps-plugin/testData/comparison/classMembersOnlyChanged/sealedClassImplAdded/new.kt

@@ -0,0 +1,7 @@
+package test
+
+sealed class Base {
+    class A : Base()
+    class B : Base()
+    class C : Base()
+}

jps-plugin/testData/comparison/classMembersOnlyChanged/sealedClassImplAdded/old.kt

@@ -0,0 +1,6 @@
+package test
+
+sealed class Base {
+    class A : Base()
+    class B : Base()
+}

jps-plugin/testData/comparison/classMembersOnlyChanged/sealedClassImplAdded/result.out

@@ -0,0 +1,5 @@
+ADDED: class Base$C.class
+changes in test/Base.A: NONE
+changes in test/Base.B: NONE
+changes in test/Base: CLASS_SIGNATURE, MEMBERS
+    [C]

jps-plugin/testData/incremental/classHierarchyAffected/sealedClassImplAdded/Base.kt

@@ -0,0 +1,4 @@
+sealed class Base {
+    class A : Base()
+    class B : Base()
+}

jps-plugin/testData/incremental/classHierarchyAffected/sealedClassImplAdded/Base.kt.new.1

@@ -0,0 +1,5 @@
+sealed class Base {
+    class A : Base()
+    class B : Base()
+    class C : Base()
+}

jps-plugin/testData/incremental/classHierarchyAffected/sealedClassImplAdded/build.log

@@ -0,0 +1,29 @@
+Cleaning output files:
+out/production/module/Base$A.class
+out/production/module/Base$B.class
+out/production/module/Base.class
+End of files
+Compiling files:
+src/Base.kt
+End of files
+Cleaning output files:
+out/production/module/META-INF/module.kotlin_module
+out/production/module/UseKt.class
+End of files
+Compiling files:
+src/use.kt
+End of files
+COMPILATION FAILED
+'when' expression must be exhaustive or contain an 'else' branch
+
+
+Cleaning output files:
+out/production/module/Base$A.class
+out/production/module/Base$B.class
+out/production/module/Base$C.class
+out/production/module/Base.class
+End of files
+Compiling files:
+src/Base.kt
+src/use.kt
+End of files

jps-plugin/testData/incremental/classHierarchyAffected/sealedClassImplAdded/use.kt

@@ -0,0 +1,7 @@
+import Base.*
+
+fun use(x: Base): String =
+        when (x) {
+            is A -> "A"
+            is B -> "B"
+        }

jps-plugin/testData/incremental/classHierarchyAffected/sealedClassImplAdded/use.kt.new.2

@@ -0,0 +1,8 @@
+import Base.*
+
+fun use(x: Base): String =
+        when (x) {
+            is A -> "A"
+            is B -> "B"
+            is C -> "C"
+        }