GradleBuildScript: throw exception when trying to change level of language features to disable in multiplatform & fix tests

idea/idea-gradle/src/org/jetbrains/kotlin/idea/configuration/GradleBuildScriptManipulator.kt

@@ -92,6 +92,16 @@ fun GradleBuildScriptManipulator<*>.useNewSyntax(kotlinPluginName: String, gradl
     return !hasOldApply
 }
 
+fun GradleBuildScriptManipulator<*>.usesNewMultiplatform(): Boolean {
+    val fileText = runReadAction { scriptFile.text }
+    return fileText.contains("multiplatform")
+}
+
+fun LanguageFeature.State.assertApplicableInMultiplatform() {
+    if (this == LanguageFeature.State.ENABLED_WITH_ERROR || this == LanguageFeature.State.DISABLED)
+        throw UnsupportedOperationException("Disabling the language feature is unsupported for multiplatform")
+}
+
 private val MIN_GRADLE_VERSION_FOR_API_AND_IMPLEMENTATION = GradleVersion.version("3.4")
 
 fun GradleVersion.scope(directive: String): String {

idea/idea-gradle/src/org/jetbrains/kotlin/idea/configuration/GroovyBuildScriptManipulator.kt

@@ -14,7 +14,6 @@ import org.gradle.util.GradleVersion
 import org.jetbrains.kotlin.cli.common.arguments.CliArgumentStringBuilder.buildArgumentString
 import org.jetbrains.kotlin.cli.common.arguments.CliArgumentStringBuilder.replaceLanguageFeature
 import org.jetbrains.kotlin.config.LanguageFeature
-import org.jetbrains.kotlin.idea.configuration.GroovyBuildScriptManipulator.Companion.getBlockOrCreate
 import org.jetbrains.kotlin.idea.configuration.KotlinWithGradleConfigurator.Companion.getBuildScriptSettingsPsiFile
 import org.jetbrains.kotlin.idea.util.application.runReadAction
 import org.jetbrains.kotlin.idea.util.module
@@ -156,6 +155,7 @@ class GroovyBuildScriptManipulator(
         forTests: Boolean
     ): PsiElement? {
         if (usesNewMultiplatform()) {
+            state.assertApplicableInMultiplatform()
             val kotlinBlock = scriptFile.getBlockOrCreate("kotlin")
             val sourceSetsBlock = kotlinBlock.getBlockOrCreate("sourceSets")
             val allBlock = sourceSetsBlock.getBlockOrCreate("all")
@@ -251,11 +251,6 @@ class GroovyBuildScriptManipulator(
             )
     }
 
-    private fun usesNewMultiplatform(): Boolean {
-        val fileText = runReadAction { scriptFile.text }
-        return fileText.contains("multiplatform")
-    }
-
     private fun GrClosableBlock.addParameterAssignment(
         parameterName: String,
         defaultValue: String,

idea/idea-gradle/src/org/jetbrains/kotlin/idea/configuration/KotlinBuildScriptManipulator.kt

@@ -299,17 +299,13 @@ class KotlinBuildScriptManipulator(
         }
     }
 
-    private fun usesNewMultiplatform(): Boolean {
-        val fileText = runReadAction { scriptFile.text }
-        return fileText.contains("multiplatform")
-    }
-
     private fun KtFile.changeLanguageFeatureConfiguration(
         feature: LanguageFeature,
         state: LanguageFeature.State,
         forTests: Boolean
     ): PsiElement? {
         if (usesNewMultiplatform()) {
+            state.assertApplicableInMultiplatform()
             return findOrCreateScriptInitializer("kotlin")
                 ?.findOrCreateBlock("sourceSets")
                 ?.findOrCreateBlock("all")

idea/idea-gradle/tests/org/jetbrains/kotlin/idea/codeInsight/gradle/GradleConfiguratorPlatformSpecificTest.kt

@@ -13,22 +13,6 @@ import org.jetbrains.plugins.gradle.tooling.annotation.TargetVersions
 import org.junit.Test
 
 class GradleConfiguratorPlatformSpecificTest : GradleImportingTestCase() {
-    @TargetVersions("4.7+")
-    @Test
-    fun testDisableFeatureSupportMultiplatform() {
-        val files = importProjectFromTestData()
-        // now it's impossible to disable feature in multiplatform
-        runInEdtAndWait {
-            myTestFixture.project.executeWriteCommand("") {
-                KotlinWithGradleConfigurator.changeFeatureConfiguration(
-                    myTestFixture.module, LanguageFeature.InlineClasses, LanguageFeature.State.DISABLED, false
-                )
-            }
-
-            checkFiles(files)
-        }
-    }
-
     @TargetVersions("4.7+")
     @Test
     fun testEnableFeatureSupportMultiplatform() {