[Native] Clean up nested comment when exporting kdoc to objc header (#4410)

* [Native] Clean up nested comment when exporting kdoc to objc header

* [kdoc-export] Add test witg nested comment block

* Remove redundant assert

Co-authored-by: Vladimir Ivanov <vladimir.d.ivanov@jetbrains.com>

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/objcexport/StubRenderer.kt

@@ -18,9 +18,14 @@ object StubRenderer {
             val kDoc = if (shouldExportKDoc) {
                 descriptor?.extractKDocString()?.let {
                     if (it.isNotEmpty()) {  // sometimes `findDoc` return empty string; is it a bug?
+                        // Nested comment is allowed inside of preformatted ``` block in kdoc but not in ObjC
+                        val kdocClean =
+                                if (it.startsWith("/**") && it.endsWith("*/"))
+                                    "/**${it.substring(3, it.length - 2).replace("*/", "**").replace("/*", "**")}*/"
+                                else it
                         +"" // Probably makes the output more readable.
-                        it.lines().forEach { it.trim().let {
-                                if (it[0] == '*') +" $it"
+                        kdocClean.lines().forEach { it.trim().let {
+                                if (it.isNotEmpty() && it[0] == '*') +" $it"
                                 else +"$it"
                             }
                         }

kotlin-native/backend.native/tests/objcexport/expectedLazy.h

@@ -548,6 +548,44 @@ __attribute__((swift_name("KDocExport")))
 @property int32_t yxxyz __attribute__((swift_name("yxxyz")));
 @end;
 
+__attribute__((swift_name("SomeClassWithProperty")))
+@interface KtSomeClassWithProperty : KtBase
+- (instancetype)init __attribute__((swift_name("init()"))) __attribute__((objc_designated_initializer));
++ (instancetype)new __attribute__((availability(swift, unavailable, message="use object initializers instead")));
+
+/**
+ * Returns dispatcher that executes coroutines immediately when it is already in the right context
+ * (e.g. current looper is the same as this handler's looper) without an additional [re-dispatch][CoroutineDispatcher.dispatch].
+ *
+ * Immediate dispatcher is safe from stack overflows and in case of nested invocations forms event-loop similar to [Dispatchers.Unconfined].
+ * The event loop is an advanced topic and its implications can be found in [Dispatchers.Unconfined] documentation.
+ * The formed event-loop is shared with [Unconfined] and other immediate dispatchers, potentially overlapping tasks between them.
+ *
+ * Example of usage:
+ * ```
+ * suspend fun updateUiElement(val text: String) {
+ *   **
+ *    * If it is known that updateUiElement can be invoked both from the Main thread and from other threads,
+ *    * `immediate` dispatcher is used as a performance optimization to avoid unnecessary dispatch.
+ *    *
+ *    * In that case, when `updateUiElement` is invoked from the Main thread, `uiElement.text` will be
+ *    * invoked immediately without any dispatching, otherwise, the `Dispatchers.Main` dispatch cycle will be triggered.
+ *    **
+ *   withContext(Dispatchers.Main.immediate) {
+ *     uiElement.text = text
+ *   }
+ *   // Do context-independent logic such as logging
+ * }
+ * ```
+ *
+ * Method may throw [UnsupportedOperationException] if immediate dispatching is not supported by current dispatcher,
+ * please refer to specific dispatcher documentation.
+ *
+ * [Dispatchers.Main] supports immediate execution for Android, JavaFx and Swing platforms.
+ */
+@property (readonly) KtSomeClassWithProperty *heavyFormattedKDocFoo __attribute__((swift_name("heavyFormattedKDocFoo")));
+@end;
+
 __attribute__((objc_subclassing_restricted))
 __attribute__((swift_name("KdocExportKt")))
 @interface KtKdocExportKt : KtBase

kotlin-native/backend.native/tests/objcexport/kdocExport.kt

@@ -42,4 +42,39 @@ class KDocExport() {
  * Check for additional comment (note) below
  */
 @Throws(IllegalArgumentException::class)
-fun whatever(a:String) = a
+fun whatever(a:String) = a
+
+public abstract class SomeClassWithProperty
+{
+    /**
+     * Returns dispatcher that executes coroutines immediately when it is already in the right context
+     * (e.g. current looper is the same as this handler's looper) without an additional [re-dispatch][CoroutineDispatcher.dispatch].
+     *
+     * Immediate dispatcher is safe from stack overflows and in case of nested invocations forms event-loop similar to [Dispatchers.Unconfined].
+     * The event loop is an advanced topic and its implications can be found in [Dispatchers.Unconfined] documentation.
+     * The formed event-loop is shared with [Unconfined] and other immediate dispatchers, potentially overlapping tasks between them.
+     *
+     * Example of usage:
+     * ```
+     * suspend fun updateUiElement(val text: String) {
+     *   /*
+     *    * If it is known that updateUiElement can be invoked both from the Main thread and from other threads,
+     *    * `immediate` dispatcher is used as a performance optimization to avoid unnecessary dispatch.
+     *    *
+     *    * In that case, when `updateUiElement` is invoked from the Main thread, `uiElement.text` will be
+     *    * invoked immediately without any dispatching, otherwise, the `Dispatchers.Main` dispatch cycle will be triggered.
+     *    */
+     *   withContext(Dispatchers.Main.immediate) {
+     *     uiElement.text = text
+     *   }
+     *   // Do context-independent logic such as logging
+     * }
+     * ```
+     *
+     * Method may throw [UnsupportedOperationException] if immediate dispatching is not supported by current dispatcher,
+     * please refer to specific dispatcher documentation.
+     *
+     * [Dispatchers.Main] supports immediate execution for Android, JavaFx and Swing platforms.
+     */
+    public abstract val heavyFormattedKDocFoo: SomeClassWithProperty
+}