Fix arguments processing with scriting with old backend by default

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/jvmArguments.kt

@@ -202,11 +202,13 @@ fun CompilerConfiguration.configureAdvancedJvmOptions(arguments: K2JVMCompilerAr
 
     put(JVMConfigurationKeys.PARAMETERS_METADATA, arguments.javaParameters)
 
+    // TODO: ignore previous configuration value when we do not need old backend in scripting by default
+    val useOldBackend = arguments.useOldBackend || get(JVMConfigurationKeys.IR) == false
     val useIR = arguments.useFir ||
             if (languageVersionSettings.supportsFeature(LanguageFeature.JvmIrEnabledByDefault)) {
-                !arguments.useOldBackend
+                !useOldBackend
             } else {
-                arguments.useIR && !arguments.useOldBackend
+                arguments.useIR && !useOldBackend
             }
 
     if (arguments.useIR && arguments.useOldBackend) {

plugins/scripting/scripting-compiler/tests/org/jetbrains/kotlin/scripting/compiler/plugin/ScriptingCompilerPluginTest.kt

@@ -25,6 +25,7 @@ import org.jetbrains.kotlin.compiler.plugin.ComponentRegistrar
 import org.jetbrains.kotlin.config.CompilerConfiguration
 import org.jetbrains.kotlin.config.JVMConfigurationKeys
 import org.jetbrains.kotlin.scripting.compiler.plugin.impl.reporter
+import org.jetbrains.kotlin.scripting.compiler.plugin.impl.updateWithCompilerOptions
 import org.jetbrains.kotlin.scripting.configuration.ScriptingConfigurationKeys
 import org.jetbrains.kotlin.scripting.definitions.SCRIPT_DEFINITION_MARKERS_PATH
 import org.jetbrains.kotlin.scripting.definitions.discoverScriptTemplatesInClasspath
@@ -76,6 +77,14 @@ class ScriptingCompilerPluginTest : TestCase() {
         return KotlinCoreEnvironment.createForTests(disposable, configuration, EnvironmentConfigFiles.JVM_CONFIG_FILES)
     }
 
+    fun testUseOldBackendPreservedOnOptionsUpdate() {
+        val configuration = KotlinTestUtils.newConfiguration(ConfigurationKind.NO_KOTLIN_REFLECT, TestJdkKind.FULL_JDK).apply {
+            put(JVMConfigurationKeys.IR, false)
+            updateWithCompilerOptions(emptyList())
+        }
+        Assert.assertEquals(configuration[JVMConfigurationKeys.IR], false)
+    }
+
     fun testScriptResolverEnvironmentArgsParsing() {
 
         val longStr = (1..100).joinToString("\\,") { """\" $it aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa \\""" }