[ULC] Add compiler flag -Xdisable-ultra-light-classes to fallback to light implementation in CLI

compiler/light-classes/src/org/jetbrains/kotlin/asJava/LightClassGenerationSupport.kt

@@ -57,6 +57,8 @@ abstract class LightClassGenerationSupport {
         ConstantExpressionEvaluator(moduleDescriptor, languageVersionSettings, expression.project)
     }
 
+    abstract val useUltraLightClasses: Boolean
+
     fun createUltraLightClassForFacade(
         manager: PsiManager,
         facadeClassFqName: FqName,
@@ -64,6 +66,8 @@ abstract class LightClassGenerationSupport {
         files: Collection<KtFile>,
     ): KtUltraLightClassForFacade? {
 
+        if (!useUltraLightClasses) return null
+
         if (files.any { it.isScript() }) return null
 
         val filesToSupports: List<Pair<KtFile, KtUltraLightSupport>> = files.map {
@@ -80,6 +84,9 @@ abstract class LightClassGenerationSupport {
     }
 
     fun createUltraLightClass(element: KtClassOrObject): KtUltraLightClass? {
+
+        if (!useUltraLightClasses) return null
+
         if (element.shouldNotBeVisibleAsLightClass()) {
             return null
         }
@@ -101,7 +108,7 @@ abstract class LightClassGenerationSupport {
     }
 
     fun createUltraLightClassForScript(script: KtScript): KtUltraLightClassForScript? =
-        KtUltraLightClassForScript(script, support = getUltraLightClassSupport(script))
+        if (useUltraLightClasses) KtUltraLightClassForScript(script, support = getUltraLightClassSupport(script)) else null
 
     companion object {
         @JvmStatic

compiler/light-classes/src/org/jetbrains/kotlin/asJava/classes/KtLightClassForFacade.kt

@@ -269,10 +269,11 @@ open class KtLightClassForFacade constructor(
 
             val manager = PsiManager.getInstance(project)
 
-            return if (!KtUltraLightSupport.forceUsingOldLightClasses && Registry.`is`("kotlin.use.ultra.light.classes", true))
-                LightClassGenerationSupport.getInstance(project).createUltraLightClassForFacade(manager, fqName, stubValue, sources)
+            return LightClassGenerationSupport.getInstance(project).run {
+                if (useUltraLightClasses) createUltraLightClassForFacade(manager, fqName, stubValue, sources)
                     ?: error { "Unable to create UL class for facade" }
-            else KtLightClassForFacade(manager, fqName, stubValue, sources)
+                else KtLightClassForFacade(manager, fqName, stubValue, sources)
+            }
         }
 
         fun createForFacade(

compiler/light-classes/src/org/jetbrains/kotlin/asJava/classes/KtLightClassForScript.kt

@@ -208,9 +208,12 @@ open class KtLightClassForScript(val script: KtScript) : KtLazyLightClass(script
                 return null
             }
 
-            if (!forceUsingOldLightClasses && Registry.`is`("kotlin.use.ultra.light.classes", true)) {
-                return LightClassGenerationSupport.getInstance(script.project).createUltraLightClassForScript(script)
-                    ?: error("UL class cannot be created for script")
+            if (!forceUsingOldLightClasses) {
+                LightClassGenerationSupport.getInstance(script.project).run {
+                    if (useUltraLightClasses) {
+                        return createUltraLightClassForScript(script) ?: error("UL class cannot be created for script")
+                    }
+                }
             }
 
             return KtLightClassForScript(script)

compiler/light-classes/src/org/jetbrains/kotlin/asJava/classes/KtLightClassForSourceDeclaration.kt

@@ -356,9 +356,13 @@ abstract class KtLightClassForSourceDeclaration(
                 return null
             }
 
-            if (!forceUsingOldLightClasses && Registry.`is`("kotlin.use.ultra.light.classes", true)) {
-                return LightClassGenerationSupport.getInstance(classOrObject.project).createUltraLightClass(classOrObject)
-                    ?: error { "Unable to create UL class for ${classOrObject::javaClass.name}" }
+            if (!forceUsingOldLightClasses) {
+                LightClassGenerationSupport.getInstance(classOrObject.project).run {
+                    if (useUltraLightClasses) {
+                        return createUltraLightClass(classOrObject)
+                            ?: error { "Unable to create UL class for ${classOrObject::javaClass.name}" }
+                    }
+                }
             }
 
             return when {