Treat nested class of header class as header

Note that the quick fix to implement header class works incorrectly when
that class has nested classes at the moment; this should be fixed
separately

 #KT-15494 Fixed
 #KT-18573 Fixed

idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/PlatformHeaderAnnotator.kt

@@ -29,11 +29,12 @@ import org.jetbrains.kotlin.idea.caches.resolve.findModuleDescriptor
 import org.jetbrains.kotlin.idea.core.toDescriptor
 import org.jetbrains.kotlin.idea.project.TargetPlatformDetector
 import org.jetbrains.kotlin.lexer.KtTokens
+import org.jetbrains.kotlin.psi.KtClassOrObject
 import org.jetbrains.kotlin.psi.KtDeclaration
+import org.jetbrains.kotlin.psi.KtPsiUtil
 import org.jetbrains.kotlin.resolve.BindingTraceContext
 import org.jetbrains.kotlin.resolve.TargetPlatform
 import org.jetbrains.kotlin.resolve.checkers.HeaderImplDeclarationChecker
-import org.jetbrains.kotlin.resolve.diagnostics.Diagnostics
 import org.jetbrains.kotlin.resolve.diagnostics.SimpleDiagnostics
 
 val ModuleDescriptor.sourceKind: SourceKind
@@ -55,7 +56,7 @@ val ModuleDescriptor.allImplementingCompatibleModules
 class PlatformHeaderAnnotator : Annotator {
     override fun annotate(element: PsiElement, holder: AnnotationHolder) {
         val declaration = element as? KtDeclaration ?: return
-        if (!declaration.hasModifier(KtTokens.HEADER_KEYWORD)) return
+        if (!isHeaderDeclaration(declaration)) return
 
         if (TargetPlatformDetector.getPlatform(declaration.containingKtFile) !is TargetPlatform.Default) return
 
@@ -78,4 +79,9 @@ class PlatformHeaderAnnotator : Annotator {
 
         KotlinPsiChecker().annotateElement(declaration, holder, SimpleDiagnostics(filteredList))
     }
+
+    private fun isHeaderDeclaration(declaration: KtDeclaration): Boolean {
+        return declaration.hasModifier(KtTokens.HEADER_KEYWORD) ||
+               declaration is KtClassOrObject && KtPsiUtil.getOutermostClassOrObject(declaration)?.hasModifier(KtTokens.HEADER_KEYWORD) == true
+    }
 }

idea/testData/multiModuleHighlighting/multiplatform/nestedClassWithoutImpl/common/common.kt

@@ -0,0 +1,15 @@
+package a
+
+header class A {
+    class Nested
+}
+
+header class B {
+    class Nested {
+        fun foo(s: String)
+    }
+}
+
+header class C {
+    <error>header</error> inner class Inner
+}

idea/testData/multiModuleHighlighting/multiplatform/nestedClassWithoutImpl/jvm/jvm.kt

@@ -0,0 +1,11 @@
+package a
+
+impl class <error>A</error>
+
+impl class B {
+    impl class <error>Nested</error>
+}
+
+impl class C {
+    impl inner class Inner
+}

idea/testData/multiModuleQuickFix/enum/header/header.kt

@@ -6,12 +6,4 @@ header enum class <caret>MyEnum {
     LAST;
 
     val num: Int
-
-    companion object {
-        fun byNum(num: Int): MyEnum = when (num) {
-            1 -> FIRST
-            2 -> SECOND
-            else -> LAST
-        }
-    }
-}
+}

idea/testData/multiModuleQuickFix/enum/header/header.kt.after

@@ -6,12 +6,4 @@ header enum class MyEnum {
     LAST;
 
     val num: Int
-
-    companion object {
-        fun byNum(num: Int): MyEnum = when (num) {
-            1 -> FIRST
-            2 -> SECOND
-            else -> LAST
-        }
-    }
-}
+}

idea/testData/multiModuleQuickFix/enum/js/MyEnum.kt.after

@@ -4,14 +4,7 @@ impl enum class MyEnum {
     SECOND,
     LAST;
 
-    companion object {
-        fun byNum(num: Int): MyEnum = when (num) {
-            1 -> FIRST
-            2 -> SECOND
-            else -> LAST
-        }
-    }
-
     impl val num: Int
         get() = TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
+
 }

idea/testData/multiModuleQuickFix/nested/header/header.kt

@@ -4,10 +4,10 @@ header class <caret>WithNested {
     fun foo(): Int
 
     class Nested {
-        fun bar() = "Nested"
+        fun bar()
     }
 
     inner class Inner {
-        fun baz() = "Inner"
+        fun baz()
     }
-}
+}

idea/testData/multiModuleQuickFix/nested/header/header.kt.after

@@ -4,10 +4,10 @@ header class WithNested {
     fun foo(): Int
 
     class Nested {
-        fun bar() = "Nested"
+        fun bar()
     }
 
     inner class Inner {
-        fun baz() = "Inner"
+        fun baz()
     }
-}
+}

idea/testData/multiModuleQuickFix/nested/jvm/WithNested.kt.after

@@ -2,11 +2,11 @@
 impl class WithNested {
 
     class Nested {
-        fun bar() = "Nested"
+        fun bar()
     }
 
     inner class Inner {
-        fun baz() = "Inner"
+        fun baz()
     }
 
     impl fun foo(): Int {

idea/testData/multiModuleQuickFix/sealed/header/header.kt

@@ -1,7 +1,7 @@
 // "Create header class implementation for platform JS" "true"
 
 header sealed class <caret>Sealed {
-    object Obj : Sealed()
+    object Obj : Sealed
 
-    class Klass(val x: Int) : Sealed()
+    class Klass(x: Int) : Sealed
 }

idea/testData/multiModuleQuickFix/sealed/header/header.kt.after

@@ -1,7 +1,7 @@
 // "Create header class implementation for platform JS" "true"
 
 header sealed class Sealed {
-    object Obj : Sealed()
+    object Obj : Sealed
 
-    class Klass(val x: Int) : Sealed()
+    class Klass(x: Int) : Sealed
 }

idea/testData/multiModuleQuickFix/sealed/js/Sealed.kt.after

@@ -1,6 +1,6 @@
 // Sealed: to be implemented
 impl sealed class Sealed {
-    object Obj : Sealed()
+    object Obj : Sealed
 
-    class Klass(val x: Int) : Sealed()
+    class Klass(x: Int) : Sealed
 }

idea/tests/org/jetbrains/kotlin/idea/caches/resolve/MultiModuleHighlightingTest.kt

@@ -284,5 +284,9 @@ open class MultiModuleHighlightingTest : AbstractMultiModuleHighlightingTest() {
                 }
             })
         }
+
+        fun testNestedClassWithoutImpl() {
+            doMultiPlatformTest(TargetPlatformKind.Jvm[JvmTarget.JVM_1_6])
+        }
     }
 }