[ObjCExport] Add nullable dependency parameter failing test

KT-66068

native/objcexport-header-generator/impl/analysis-api/src/org/jetbrains/kotlin/objcexport/extras/requiresForwardDeclaration.kt

@@ -5,6 +5,8 @@
 
 package org.jetbrains.kotlin.objcexport.extras
 
+import org.jetbrains.kotlin.backend.konan.objcexport.ObjCNonNullReferenceType
+import org.jetbrains.kotlin.backend.konan.objcexport.ObjCNullableReferenceType
 import org.jetbrains.kotlin.backend.konan.objcexport.ObjCReferenceType
 import org.jetbrains.kotlin.tooling.core.MutableExtras
 import org.jetbrains.kotlin.tooling.core.extrasKeyOf
@@ -16,7 +18,12 @@ private val requiresForwardDeclarationKey = extrasKeyOf<Boolean>("isForwardDecla
  * - Default value: `false`.
  * - Example: All types used in function and method signature are expected to render forward declarations
  */
-internal val ObjCReferenceType.requiresForwardDeclaration: Boolean get() = extras[requiresForwardDeclarationKey] ?: false
+internal val ObjCReferenceType.requiresForwardDeclaration: Boolean
+    get() =
+        when (this) {
+            is ObjCNonNullReferenceType -> extras[requiresForwardDeclarationKey] ?: false
+            is ObjCNullableReferenceType -> extras[requiresForwardDeclarationKey] ?: nonNullType.requiresForwardDeclaration
+        }
 
 /**
  * ⚠️ Marks [this] [ObjCReferenceType] as 'requires forward declaration' and returns the same instance.

native/objcexport-header-generator/impl/analysis-api/src/org/jetbrains/kotlin/objcexport/translateToObjCHeader.kt

@@ -193,8 +193,9 @@ private class KtObjCExportHeaderGenerator {
             .filterIsInstance<ObjCReferenceType>()
             .onEach { type ->
                 if (!type.requiresForwardDeclaration) return@onEach
-                if (type is ObjCClassType) objCClassForwardDeclarations += type.className
+                val nonNullType = if (type is ObjCNullableReferenceType) type.nonNullType else type
-                if (type is ObjCProtocolType) objCProtocolForwardDeclarations += type.protocolName
+                if (nonNullType is ObjCClassType) objCClassForwardDeclarations += nonNullType.className
+                if (nonNullType is ObjCProtocolType) objCProtocolForwardDeclarations += nonNullType.protocolName
             }
             .mapNotNull { it.originClassId }
             .map(QueueElement::Class).toList()
@@ -237,4 +238,4 @@ private class KtObjCExportHeaderGenerator {
             additionalImports = emptyList()
         )
     }
-}
+}

native/objcexport-header-generator/test/org/jetbrains/kotlin/backend/konan/tests/ObjCExportForwardDeclarationsTest.kt

@@ -36,6 +36,11 @@ class ObjCExportForwardDeclarationsTest(
         doTest(forwardDeclarationsDir.resolve("propertyReturningClass"))
     }
 
+    @Test
+    fun `test - nullable type`() {
+        doTest(forwardDeclarationsDir.resolve("nullableType"))
+    }
+
     private fun doTest(root: File) {
         if (!root.isDirectory) fail("Expected ${root.absolutePath} to be directory")
         val generatedHeaders = generator.generateHeaders(root)

native/objcexport-header-generator/testData/forwardDeclarations/nullableType/!nullableType.h

@@ -0,0 +1,3 @@
+@class LongIterator, DoubleIterator, IntIterator;
+
+@protocol Iterator;

native/objcexport-header-generator/testData/forwardDeclarations/nullableType/Foo.kt

@@ -0,0 +1,6 @@
+class Foo {
+    fun foo(iterator: DoubleIterator? = null) = Unit
+    fun foo(): LongIterator? = null
+}
+
+var prop: IntIterator? = null