[JVM_IR] Fix mangling of default argument stubs for internal methods.

The MethodSignatureMapper expected to be able to look at the body
of the default argument stub. That is of course not possible when
it is from an external dependency.

Instead, we go through the attribute owner to get to the method
the stub is a default argument adapter for.

compiler/fir/fir2ir/tests/org/jetbrains/kotlin/codegen/FirCompileKotlinAgainstKotlinTestGenerated.java

@@ -178,6 +178,11 @@ public class FirCompileKotlinAgainstKotlinTestGenerated extends AbstractFirCompi
         runTest("compiler/testData/compileKotlinAgainstKotlin/internalSetterOverridden.kt");
     }
 
+    @TestMetadata("internalWithDefaultArgs.kt")
+    public void testInternalWithDefaultArgs() throws Exception {
+        runTest("compiler/testData/compileKotlinAgainstKotlin/internalWithDefaultArgs.kt");
+    }
+
     @TestMetadata("internalWithOtherModuleName.kt")
     public void testInternalWithOtherModuleName() throws Exception {
         runTest("compiler/testData/compileKotlinAgainstKotlin/internalWithOtherModuleName.kt");

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/MethodSignatureMapper.kt

@@ -105,12 +105,12 @@ class MethodSignatureMapper(private val context: JvmBackendContext) {
     private fun mangleMemberNameIfRequired(name: String, function: IrSimpleFunction): String {
         val newName = JvmCodegenUtil.sanitizeNameIfNeeded(name, context.state.languageVersionSettings)
 
-        val suffix = when {
-            function.isTopLevel ->
-                if (function.isInvisibleInMultifilePart()) function.parentAsClass.name.asString() else null
-            function.shouldMangleAsInternal() ->
-                NameUtils.sanitizeAsJavaIdentifier(getModuleName(function))
-            else -> null
+        val suffix = if (function.isTopLevel) {
+            if (function.isInvisibleInMultifilePart()) function.parentAsClass.name.asString() else null
+        } else {
+            function.getInternalFunctionForManglingIfNeeded()?.let {
+                NameUtils.sanitizeAsJavaIdentifier(getModuleName(it))
+            }
         } ?: return newName
 
         if (function.origin == IrDeclarationOrigin.FUNCTION_FOR_DEFAULT_PARAMETER) {
@@ -127,15 +127,20 @@ class MethodSignatureMapper(private val context: JvmBackendContext) {
                 (DescriptorVisibilities.isPrivate(suspendFunctionOriginal().visibility) ||
                         originalForDefaultAdapter?.isInvisibleInMultifilePart() == true)
 
-    private fun IrSimpleFunction.shouldMangleAsInternal(): Boolean =
-        (origin != JvmLoweredDeclarationOrigin.STATIC_INLINE_CLASS_CONSTRUCTOR &&
-                visibility == DescriptorVisibilities.INTERNAL &&
-                !isPublishedApi())
-                || originalForDefaultAdapter?.shouldMangleAsInternal() == true
+    private fun IrSimpleFunction.getInternalFunctionForManglingIfNeeded(): IrSimpleFunction? {
+        if (origin != JvmLoweredDeclarationOrigin.STATIC_INLINE_CLASS_CONSTRUCTOR &&
+            visibility == DescriptorVisibilities.INTERNAL &&
+            !isPublishedApi()
+        ) {
+            return this
+        }
+        originalForDefaultAdapter?.getInternalFunctionForManglingIfNeeded()?.let { return it }
+        return null
+    }
 
     private val IrSimpleFunction.originalForDefaultAdapter: IrSimpleFunction?
         get() = if (origin == IrDeclarationOrigin.FUNCTION_FOR_DEFAULT_PARAMETER) {
-            ((body?.statements?.lastOrNull() as? IrReturn)?.value as? IrCall)?.symbol?.owner
+            (attributeOwnerId as IrFunction).symbol.owner as IrSimpleFunction
         } else null
 
     private fun getModuleName(function: IrSimpleFunction): String =

compiler/testData/compileKotlinAgainstKotlin/internalWithDefaultArgs.kt

@@ -0,0 +1,15 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// IGNORE_BACKEND: NATIVE
+// FILE: A.kt
+
+package a
+
+class Box() {
+    internal fun result(value: String = "OK"): String = value
+}
+
+// FILE: B.kt
+
+fun box(): String {
+    return a.Box().result()
+}

compiler/tests/org/jetbrains/kotlin/codegen/CompileKotlinAgainstKotlinTestGenerated.java

@@ -183,6 +183,11 @@ public class CompileKotlinAgainstKotlinTestGenerated extends AbstractCompileKotl
         runTest("compiler/testData/compileKotlinAgainstKotlin/internalSetterOverridden.kt");
     }
 
+    @TestMetadata("internalWithDefaultArgs.kt")
+    public void testInternalWithDefaultArgs() throws Exception {
+        runTest("compiler/testData/compileKotlinAgainstKotlin/internalWithDefaultArgs.kt");
+    }
+
     @TestMetadata("internalWithOtherModuleName.kt")
     public void testInternalWithOtherModuleName() throws Exception {
         runTest("compiler/testData/compileKotlinAgainstKotlin/internalWithOtherModuleName.kt");

compiler/tests/org/jetbrains/kotlin/codegen/ir/IrCompileKotlinAgainstKotlinTestGenerated.java

@@ -178,6 +178,11 @@ public class IrCompileKotlinAgainstKotlinTestGenerated extends AbstractIrCompile
         runTest("compiler/testData/compileKotlinAgainstKotlin/internalSetterOverridden.kt");
     }
 
+    @TestMetadata("internalWithDefaultArgs.kt")
+    public void testInternalWithDefaultArgs() throws Exception {
+        runTest("compiler/testData/compileKotlinAgainstKotlin/internalWithDefaultArgs.kt");
+    }
+
     @TestMetadata("internalWithOtherModuleName.kt")
     public void testInternalWithOtherModuleName() throws Exception {
         runTest("compiler/testData/compileKotlinAgainstKotlin/internalWithOtherModuleName.kt");

compiler/tests/org/jetbrains/kotlin/codegen/ir/JvmIrAgainstOldBoxTestGenerated.java

@@ -178,6 +178,11 @@ public class JvmIrAgainstOldBoxTestGenerated extends AbstractJvmIrAgainstOldBoxT
         runTest("compiler/testData/compileKotlinAgainstKotlin/internalSetterOverridden.kt");
     }
 
+    @TestMetadata("internalWithDefaultArgs.kt")
+    public void testInternalWithDefaultArgs() throws Exception {
+        runTest("compiler/testData/compileKotlinAgainstKotlin/internalWithDefaultArgs.kt");
+    }
+
     @TestMetadata("internalWithOtherModuleName.kt")
     public void testInternalWithOtherModuleName() throws Exception {
         runTest("compiler/testData/compileKotlinAgainstKotlin/internalWithOtherModuleName.kt");

compiler/tests/org/jetbrains/kotlin/codegen/ir/JvmOldAgainstIrBoxTestGenerated.java

@@ -178,6 +178,11 @@ public class JvmOldAgainstIrBoxTestGenerated extends AbstractJvmOldAgainstIrBoxT
         runTest("compiler/testData/compileKotlinAgainstKotlin/internalSetterOverridden.kt");
     }
 
+    @TestMetadata("internalWithDefaultArgs.kt")
+    public void testInternalWithDefaultArgs() throws Exception {
+        runTest("compiler/testData/compileKotlinAgainstKotlin/internalWithDefaultArgs.kt");
+    }
+
     @TestMetadata("internalWithOtherModuleName.kt")
     public void testInternalWithOtherModuleName() throws Exception {
         runTest("compiler/testData/compileKotlinAgainstKotlin/internalWithOtherModuleName.kt");