[K/JS] Remove unnecessery changes + add KDoc for the `PrepareSuspendFunctionsToExportLowering` class
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/PrepareSuspendFunctionsToExportLowering.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/PrepareSuspendFunctionsToExportLowering.kt
index 0749ab7..639bcc5 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/PrepareSuspendFunctionsToExportLowering.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/PrepareSuspendFunctionsToExportLowering.kt
@@ -29,6 +29,71 @@
import org.jetbrains.kotlin.name.SpecialNames
import org.jetbrains.kotlin.utils.memoryOptimizedPlus
+/**
+ * The lowering generates a few functions from the original exported suspend functions
+ * to be used both from Kotlin and JS sides with minimal performance degradation
+ * It works both with top-level suspend functions and with member suspend functions
+ *
+ * For the top-level suspend functions we generate only one additional function supposed to be used only from the JS side.
+ * As an example:
+ *
+ * **Before the transformation:**
+ * ```kotlin
+ * @JsExport
+ * suspend fun foo(a: Int, b: String): String { ... }
+ * ```
+ *
+ * **After the transformation:**
+ * ```kotlin
+ * @JsExport.Ignore
+ * suspend fun foo(a: Int, b: String): String { ... }
+ *
+ * @JsExport
+ * @JsName("foo")
+ * fun foo$promisified(a: Int, b: String): Promise<String> =
+ * /* The `promisify` function is defined inside `libraries/stdlib/js/runtime/coroutinesInterop.kt` */
+ * kotlin.coroutines.promisify { foo(a, b) }
+ * ```
+ *
+ * For the member functions it's a little bit more complicated because we should take in account that they could be overridden from the JS side.
+ * To support the overriding, we introduce two more helper methods.
+ *
+ * **Before the transformation:**
+ * ```kotlin
+ * @JsExport
+ * class SomeClass {
+ * suspend fun foo(a: Int, b: String): String { ... }
+ * }
+ * ```
+ *
+ * **After the transformation:**
+ * ```kotlin
+ * @JsExport
+ * class SomeClass {
+ * @JsName("foo")
+ * // This function is used from the JS side and is supposed to be overridden from the JS side
+ * fun foo$promisified(a: Int, b: String): Promise<String> =
+ * kotlin.coroutines.promisify { this.foo$original(a, b) }
+ *
+ * @JsExport.Ignore
+ * // This function is supposed to be overridden from the Kotlin side
+ * suspend fun foo$original(a: Int, b: String): String { ... }
+ *
+ * @JsExport.Ignore
+ * // This function is used on the call side
+ * suspend fun foo(a: Int, b: String): String =
+ * if (this.foo === SomeClass.prototype.foo) {
+ * this.foo$original(a, b)
+ * } else {
+ * /* The `await` function is defined inside `libraries/stdlib/js/runtime/coroutinesInterop.kt` */
+ * kotlin.coroutines.await(this.foo$promisified(a, b))
+ * }
+ * }
+ * ```
+ *
+ * Such a trick with the 3 functions helps us to call the original function instead of the promisified variant until the function is not overridden from the JS side
+ * and also helps us to not recompile each child class if body of the exported function is changed
+ */
internal class PrepareSuspendFunctionsToExportLowering(private val context: JsIrBackendContext) : DeclarationTransformer {
companion object {
private const val PROMISIFIED_WRAPPER_SUFFIX = "\$promisified"
diff --git a/js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/JsExportDeclarationChecker.kt b/js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/JsExportDeclarationChecker.kt
index b00bb32..dacdb17 100644
--- a/js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/JsExportDeclarationChecker.kt
+++ b/js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/JsExportDeclarationChecker.kt
@@ -39,7 +39,7 @@
class JsExportDeclarationChecker(
private val includeUnsignedNumbers: Boolean,
- private val allowCompanionInInterface: Boolean,
+ private val allowCompanionInInterface: Boolean
) : DeclarationChecker {
override fun check(declaration: KtDeclaration, descriptor: DeclarationDescriptor, context: DeclarationCheckerContext) {
val trace = context.trace
