KTIJ-664 [SealedClassInheritorsProvider]: IDE-specific implementation

idea/testData/checker/sealed/SealedDeclaration.kt

@@ -0,0 +1,14 @@
+// COMPILER_ARGUMENTS: -XXLanguage:+SealedInterfaces -XXLanguage:+FreedomForSealedClasses
+
+package sealed
+
+sealed class SealedDeclarationClass {
+    class AClass: SealedDeclarationClass()
+}
+
+sealed interface SealedDeclarationInterface {
+    class A: SealedDeclarationInterface
+}
+
+class B: SealedDeclarationInterface
+class BClass: SealedDeclarationClass()

idea/testData/checker/sealed/SealedInheritors.kt

@@ -0,0 +1,35 @@
+// COMPILER_ARGUMENTS: -XXLanguage:+SealedInterfaces -XXLanguage:+FreedomForSealedClasses
+package sealed
+
+class C: SealedDeclarationInterface {}
+class CClass: SealedDeclarationClass() {}
+
+class D: SealedDeclarationInterface {
+    class E: SealedDeclarationInterface {
+        class F: SealedDeclarationInterface
+    }
+}
+
+class DClass: SealedDeclarationClass() {
+    class EClass: SealedDeclarationClass() {
+        class FClass: SealedDeclarationClass()
+    }
+}
+
+fun checkWhenNone(value: SealedDeclarationInterface): Int = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'is A', 'is B', 'is C', 'is D', 'is E', 'is F' branches or 'else' branch instead">when</error> (<warning descr="[UNUSED_EXPRESSION] The expression is unused">value</warning>) {
+}
+
+fun checkWhenNone(value: SealedDeclarationClass): Int = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'is AClass', 'is BClass', 'is CClass', 'is DClass', 'is EClass', 'is FClass' branches or 'else' branch instead">when</error> (<warning descr="[UNUSED_EXPRESSION] The expression is unused">value</warning>) {
+}
+
+fun checkWhenOneMissing(value: SealedDeclarationInterface): Int = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'is D', 'is E', 'is F' branches or 'else' branch instead">when</error> (value) {
+    is SealedDeclarationInterface.A -> 1
+    is B -> 2
+    is C -> 3
+}
+
+fun checkWhenOneMissing(value: SealedDeclarationClass): Int = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'is DClass', 'is EClass', 'is FClass' branches or 'else' branch instead">when</error> (value) {
+    is SealedDeclarationClass.AClass -> 1
+    is BClass -> 2
+    is CClass -> 3
+}

idea/testData/checker/sealed/SealedOutsidePackageInheritors.kt

@@ -0,0 +1,7 @@
+// COMPILER_ARGUMENTS: -XXLanguage:+SealedInterfaces -XXLanguage:+FreedomForSealedClasses
+package sealed.otherpackage
+import sealed.SealedDeclarationInterface
+import sealed.SealedDeclarationClass
+
+class D: <error descr="[SEALED_INHERITOR_IN_DIFFERENT_PACKAGE] Inheritor of sealed class or interface declared in package sealed but it must be in package {2} where base class is declared">SealedDeclarationInterface</error>
+class DClass: <error descr="[SEALED_INHERITOR_IN_DIFFERENT_PACKAGE] Inheritor of sealed class or interface declared in package sealed but it must be in package {2} where base class is declared">SealedDeclarationClass</error>()