[StubIr] StubOrigin improvements

1. Add `isMeta` to StubOrigin.ObjCClass and StubOrigin.ObjCProtocol. It allows to provide proper UniqId to corresponding ClassStubs.
2. Rename StubOrigin.None to StubOrigin.Synthetic because it is makes name self-explaining.

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/ObjCStubs.kt

@@ -166,7 +166,7 @@ private class ObjCMethodStubBuilder(
                             context.configuration.disableDesignatedInitializerChecks
 
                     val annotations = listOf(AnnotationStub.ObjC.Constructor(method.selector, designated))
-                    val constructor = ConstructorStub(parameters, annotations, isPrimary = false)
+                    val constructor = ConstructorStub(parameters, annotations, isPrimary = false, origin = origin)
                     constructor
                 }
                 is ObjCCategory -> {
@@ -206,7 +206,7 @@ private class ObjCMethodStubBuilder(
                             receiver = receiver,
                             typeParameters = listOf(typeParameter),
                             external = true,
-                            origin = StubOrigin.Synthetic,
+                            origin = StubOrigin.ObjCCategoryInitMethod(method),
                             annotations = annotations,
                             modality = MemberStubModality.FINAL
                     )
@@ -434,7 +434,10 @@ internal abstract class ObjCContainerStubBuilder(
         val defaultConstructor =  if (container is ObjCClass && methodToStub.values.none { it.isDefaultConstructor() }) {
             // Always generate default constructor.
             // If it is not produced for an init method, then include it manually:
-            ConstructorStub(isPrimary = false, visibility = VisibilityModifier.PROTECTED)
+            ConstructorStub(
+                    isPrimary = false,
+                    visibility = VisibilityModifier.PROTECTED,
+                    origin = StubOrigin.SyntheticDefaultConstructor)
         } else null
 
         return Pair(
@@ -482,7 +485,7 @@ internal class ObjCProtocolStubBuilder(
         private val protocol: ObjCProtocol
 ) : ObjCClassOrProtocolStubBuilder(context, protocol), StubElementBuilder {
     override fun build(): List<StubIrElement> {
-        val classStub = buildClassStub(StubOrigin.ObjCProtocol(protocol))
+        val classStub = buildClassStub(StubOrigin.ObjCProtocol(protocol, isMeta = false))
         return listOf(*metaContainerStub!!.build().toTypedArray(), classStub)
     }
 }

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/StubIr.kt

@@ -91,7 +91,17 @@ sealed class StubOrigin {
     /**
      * Special case when element of IR was generated.
      */
-    object None : StubOrigin()
+    // TODO: All "synthetic" cases should be handled separately.
+    object Synthetic : StubOrigin()
+
+    /**
+     * Denotes default constructor that was generated and has no real origin.
+     */
+    object SyntheticDefaultConstructor : StubOrigin()
+
+    class ObjCCategoryInitMethod(
+            val method: org.jetbrains.kotlin.native.interop.indexer.ObjCMethod
+    ) : StubOrigin()
 
     class ObjCMethod(
             val method: org.jetbrains.kotlin.native.interop.indexer.ObjCMethod,
@@ -104,11 +114,13 @@ sealed class StubOrigin {
     ) : StubOrigin()
 
     class ObjCClass(
-            val clazz: org.jetbrains.kotlin.native.interop.indexer.ObjCClass
+            val clazz: org.jetbrains.kotlin.native.interop.indexer.ObjCClass,
+            val isMeta: Boolean
     ) : StubOrigin()
 
     class ObjCProtocol(
-            val protocol: org.jetbrains.kotlin.native.interop.indexer.ObjCProtocol
+            val protocol: org.jetbrains.kotlin.native.interop.indexer.ObjCProtocol,
+            val isMeta: Boolean
     ) : StubOrigin()
 
     class Enum(val enum: EnumDef) : StubOrigin()
@@ -270,7 +282,7 @@ sealed class ClassStub : StubContainer(), StubElementWithOrigin, AnnotationHolde
             override val superClassInit: SuperClassInit? = null,
             override val interfaces: List<StubType> = emptyList(),
             override val properties: List<PropertyStub> = emptyList(),
-            override val origin: StubOrigin = StubOrigin.None,
+            override val origin: StubOrigin = StubOrigin.Synthetic,
             override val annotations: List<AnnotationStub> = emptyList(),
             override val childrenClasses: List<ClassStub> = emptyList(),
             override val simpleContainers: List<SimpleStubContainer> = emptyList()
@@ -316,7 +328,7 @@ class FunctionParameterStub(
         val type: StubType,
         override val annotations: List<AnnotationStub> = emptyList(),
         val isVararg: Boolean = false,
-        val origin: StubOrigin = StubOrigin.None
+        val origin: StubOrigin = StubOrigin.Synthetic
 ) : AnnotationHolder
 
 enum class MemberStubModality {
@@ -430,7 +442,8 @@ class ConstructorStub(
         override val parameters: List<FunctionParameterStub> = emptyList(),
         override val annotations: List<AnnotationStub> = emptyList(),
         val isPrimary: Boolean,
-        val visibility: VisibilityModifier = VisibilityModifier.PUBLIC
+        val visibility: VisibilityModifier = VisibilityModifier.PUBLIC,
+        val origin: StubOrigin
 ) : FunctionalStub {
 
     override fun <T, R> accept(visitor: StubIrVisitor<T, R>, data: T) =

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/StubIrBridgeBuilder.kt

@@ -73,7 +73,8 @@ class StubIrBridgeBuilder(
 
         override fun visitClass(element: ClassStub, owner: StubContainer?) {
             element.annotations.filterIsInstance<AnnotationStub.ObjC.ExternalClass>().firstOrNull()?.let {
-                if (it.protocolGetter.isNotEmpty() && element.origin is StubOrigin.ObjCProtocol) {
+                val origin = element.origin
+                if (it.protocolGetter.isNotEmpty() && origin is StubOrigin.ObjCProtocol && !origin.isMeta) {
                     val protocol = (element.origin as StubOrigin.ObjCProtocol).protocol
                     // TODO: handle the case when protocol getter stub can't be compiled.
                     generateProtocolGetter(it.protocolGetter, protocol)

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/StubIrElementBuilders.kt

@@ -73,7 +73,7 @@ internal class StructStubBuilder(
                 val offset = field.offset / 8
                 val fieldRefType = context.mirror(field.type)
                 val unwrappedFieldType = field.type.unwrapTypedefs()
-                val origin = StubOrigin.None
+                val origin = StubOrigin.Synthetic
                 if (unwrappedFieldType is ArrayType) {
                     val type = (fieldRefType as TypeMirror.ByValue).valueType
                     val annotations = if (platform == KotlinPlatform.JVM) {
@@ -115,16 +115,18 @@ internal class StructStubBuilder(
             context.bridgeComponentsBuilder.getterToBridgeInfo[readBits] = BridgeGenerationInfo("", typeInfo)
             context.bridgeComponentsBuilder.setterToBridgeInfo[writeBits] = BridgeGenerationInfo("", typeInfo)
             val kind = PropertyStub.Kind.Var(readBits, writeBits)
-            PropertyStub(field.name, kotlinType.toStubIrType(), kind, origin = StubOrigin.None)
+            PropertyStub(field.name, kotlinType.toStubIrType(), kind, origin = StubOrigin.Synthetic)
         }
 
         val superClass = context.platform.getRuntimeType("CStructVar")
         require(superClass is ClassifierStubType)
         val rawPtrConstructorParam = FunctionParameterStub("rawPtr", context.platform.getRuntimeType("NativePtr"))
+        val origin = StubOrigin.Struct(decl)
         val primaryConstructor = ConstructorStub(
                 parameters = listOf(rawPtrConstructorParam),
                 isPrimary = true,
-                annotations = emptyList()
+                annotations = emptyList(),
+                origin = origin
         )
         val superClassInit = SuperClassInit(superClass, listOf(GetConstructorParameter(rawPtrConstructorParam)))
 
@@ -136,7 +138,7 @@ internal class StructStubBuilder(
 
         return listOf(ClassStub.Simple(
                 classifier,
-                origin = StubOrigin.Struct(decl),
+                origin = origin,
                 properties = fields.filterNotNull() + if (platform == KotlinPlatform.NATIVE) bitFields else emptyList(),
                 constructors = listOf(primaryConstructor),
                 methods = emptyList(),
@@ -182,7 +184,7 @@ internal class StructStubBuilder(
             val rawPtrConstructorParam = FunctionParameterStub("rawPtr", context.platform.getRuntimeType("NativePtr"))
             val superClassInit = SuperClassInit(superClass, listOf(GetConstructorParameter(rawPtrConstructorParam)))
             val origin = StubOrigin.Struct(s)
-            val primaryConstructor = ConstructorStub(listOf(rawPtrConstructorParam), emptyList(), isPrimary = true)
+            val primaryConstructor = ConstructorStub(listOf(rawPtrConstructorParam), emptyList(), isPrimary = true, origin = origin)
             listOf(ClassStub.Simple(
                     classifier,
                     ClassStubModality.NONE,
@@ -213,7 +215,7 @@ internal class EnumStubBuilder(
                 type = baseType,
                 kind = PropertyStub.Kind.Val(PropertyAccessor.Getter.GetConstructorParameter(constructorParameter)),
                 modality = MemberStubModality.OVERRIDE,
-                origin = StubOrigin.None)
+                origin = StubOrigin.Synthetic)
 
         val canonicalsByValue = enumDef.constants
                 .groupingBy { it.value }
@@ -232,11 +234,12 @@ internal class EnumStubBuilder(
             val aliases = aliasConstants.filter { it.value == constant.value }.map { EnumEntryStub.Alias(it.name) }
             EnumEntryStub(constant.name, literal, aliases)
         }
-        val primaryConstructor = ConstructorStub(listOf(constructorParameter), emptyList(), isPrimary = true)
+        val origin = StubOrigin.Enum(enumDef)
+        val primaryConstructor = ConstructorStub(listOf(constructorParameter), emptyList(), isPrimary = true, origin = origin)
         val enum = ClassStub.Enum(clazz, canonicalEntries,
                 constructors = listOf(primaryConstructor),
                 properties = listOf(valueProperty),
-                origin = StubOrigin.Enum(enumDef),
+                origin = origin,
                 interfaces = listOf(context.platform.getRuntimeType("CEnum"))
         )
         context.bridgeComponentsBuilder.enumToTypeMirror[enum] = baseTypeMirror
@@ -299,7 +302,7 @@ internal class EnumStubBuilder(
                     kind,
                     MemberStubModality.FINAL,
                     null,
-                    origin = StubOrigin.None
+                    origin = StubOrigin.Synthetic
             )
         }
         val container = SimpleStubContainer(