[JS IR] Fix export of constructor with default argument (KT-41275)

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIrBackendContext.kt

@@ -40,7 +40,7 @@ class JsIrBackendContext(
     override val irBuiltIns: IrBuiltIns,
     val symbolTable: SymbolTable,
     irModuleFragment: IrModuleFragment,
-    val additionalExportedDeclarations: Set<FqName>,
+    val additionalExportedDeclarationNames: Set<FqName>,
     override val configuration: CompilerConfiguration, // TODO: remove configuration from backend context
     override val scriptMode: Boolean = false,
     override val es6mode: Boolean = false
@@ -65,6 +65,8 @@ class JsIrBackendContext(
     val externalPackageFragment = mutableMapOf<IrFileSymbol, IrFile>()
     val externalDeclarations = hashSetOf<IrDeclaration>()
 
+    val additionalExportedDeclarations = mutableSetOf<IrDeclaration>()
+
     val bodilessBuiltInsPackageFragment: IrPackageFragment = IrExternalPackageFragmentImpl(
         DescriptorlessExternalPackageFragmentSymbol(),
         FqName("kotlin")

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/export/ExportModelGenerator.kt

@@ -331,9 +331,19 @@ class ExportModelGenerator(val context: JsIrBackendContext) {
 
         if (function.isFakeOverriddenFromAny())
             return Exportability.NotNeeded
-        if (function.name.asString().endsWith("-impl"))
+
+
+        val nameString = function.name.asString()
+        if (nameString.endsWith("-impl"))
             return Exportability.NotNeeded
 
+
+        // Workaround in case IrDeclarationOrigin.FUNCTION_FOR_DEFAULT_PARAMETER is rewritten.
+        // TODO: Properly fix KT-41613
+        if (nameString.endsWith("\$") && function.valueParameters.any { "\$mask" in it.name.asString() }) {
+            return Exportability.NotNeeded
+        }
+
         val name = function.getExportedIdentifier()
         // TODO: Use [] syntax instead of prohibiting
         if (name in allReservedWords)
@@ -379,7 +389,10 @@ private fun getExportCandidate(declaration: IrDeclaration): IrDeclarationWithNam
 }
 
 private fun shouldDeclarationBeExported(declaration: IrDeclarationWithName, context: JsIrBackendContext): Boolean {
-    if (declaration.fqNameWhenAvailable in context.additionalExportedDeclarations)
+    if (declaration.fqNameWhenAvailable in context.additionalExportedDeclarationNames)
+        return true
+
+    if (declaration in context.additionalExportedDeclarations)
         return true
 
     if (declaration.isJsExport())

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/StaticMembersLowering.kt

@@ -5,14 +5,15 @@
 
 package org.jetbrains.kotlin.ir.backend.js.lower
 
-import org.jetbrains.kotlin.backend.common.CommonBackendContext
 import org.jetbrains.kotlin.backend.common.DeclarationTransformer
+import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.backend.js.export.isExported
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.util.file
 import org.jetbrains.kotlin.ir.util.isEffectivelyExternal
 
 // Move static member declarations from classes to top level
-class StaticMembersLowering(val context: CommonBackendContext) : DeclarationTransformer {
+class StaticMembersLowering(val context: JsIrBackendContext) : DeclarationTransformer {
     override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
         (declaration.parent as? IrClass)?.let { irClass ->
             val isStatic = when (declaration) {
@@ -23,6 +24,11 @@ class StaticMembersLowering(val context: CommonBackendContext) : DeclarationTran
             }
 
             if (isStatic) {
+                // JsExport might be inherited from parent declaration which would be broken if we move it out of its parent.
+                // Marking declaration as exported explicitly.
+                if (declaration.isExported(context)) {
+                    context.additionalExportedDeclarations.add(declaration)
+                }
                 declaration.parent = irClass.file
                 irClass.file.declarations += declaration
                 return listOf()

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/NameTables.kt

@@ -312,7 +312,8 @@ class NameTables(
             parent = parent.parent
         }
 
-        return mappedNames[mapToKey(declaration)] ?: error("Can't find name for declaration ${declaration.render()}")
+        return mappedNames[mapToKey(declaration)]
+            ?: error("Can't find name for declaration ${declaration.render()}")
     }
 
     fun getNameForMemberField(field: IrField): String {

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt

@@ -316,11 +316,11 @@ private val blockDecomposerLoweringPhase = makeCustomWasmModulePhase(
 //    description = "Generate invocations to kotlin.test suite and test functions"
 //)
 //
-private val staticMembersLoweringPhase = makeWasmModulePhase(
-    ::StaticMembersLowering,
-    name = "StaticMembersLowering",
-    description = "Move static member declarations to top-level"
-)
+//private val staticMembersLoweringPhase = makeWasmModulePhase(
+//    ::StaticMembersLowering,
+//    name = "StaticMembersLowering",
+//    description = "Move static member declarations to top-level"
+//)
 
 private val builtInsLoweringPhase = makeWasmModulePhase(
     ::BuiltInsLowering,
@@ -434,7 +434,7 @@ val wasmPhases = NamedCompilerPhase(
 
             objectDeclarationLoweringPhase then
             objectUsageLoweringPhase then
-            staticMembersLoweringPhase then
+//            staticMembersLoweringPhase then
 
             validateIrAfterLowering
 )