Make CommonToolArguments.nullable

#KT-28974 Fixed

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/CommonToolArguments.kt

@@ -27,7 +27,7 @@ abstract class CommonToolArguments : Freezable(), Serializable {
     var freeArgs: List<String> by FreezableVar(emptyList())
 
     @Transient
-    var errors: ArgumentParseErrors = ArgumentParseErrors()
+    var errors: ArgumentParseErrors? = null
 
     @Argument(value = "-help", shortName = "-h", description = "Print a synopsis of standard options")
     var help: Boolean by FreezableVar(false)

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/parseCommandLineArguments.kt

@@ -38,12 +38,12 @@ private const val ADVANCED_ARGUMENT_PREFIX = "-X"
 private const val FREE_ARGS_DELIMITER = "--"
 
 data class ArgumentParseErrors(
-    val unknownArgs: MutableList<String> = SmartList<String>(),
+    val unknownArgs: MutableList<String> = SmartList(),
 
-    val unknownExtraFlags: MutableList<String> = SmartList<String>(),
+    val unknownExtraFlags: MutableList<String> = SmartList(),
 
     // Names of extra (-X...) arguments which have been passed in an obsolete form ("-Xaaa bbb", instead of "-Xaaa=bbb")
-    val extraArgumentsPassedInObsoleteForm: MutableList<String> = SmartList<String>(),
+    val extraArgumentsPassedInObsoleteForm: MutableList<String> = SmartList(),
 
     // Non-boolean arguments which have been passed multiple times, possibly with different values.
     // The key in the map is the name of the argument, the value is the last passed value.
@@ -62,11 +62,12 @@ data class ArgumentParseErrors(
 
 // Parses arguments into the passed [result] object. Errors related to the parsing will be collected into [CommonToolArguments.errors].
 fun <A : CommonToolArguments> parseCommandLineArguments(args: List<String>, result: A) {
-    val preprocessed = preprocessCommandLineArguments(args, result.errors)
-    parsePreprocessedCommandLineArguments(preprocessed, result)
+    val errors = result.errors ?: ArgumentParseErrors().also { result.errors = it }
+    val preprocessed = preprocessCommandLineArguments(args, errors)
+    parsePreprocessedCommandLineArguments(preprocessed, result, errors)
 }
 
-private fun <A : CommonToolArguments> parsePreprocessedCommandLineArguments(args: List<String>, result: A) {
+private fun <A : CommonToolArguments> parsePreprocessedCommandLineArguments(args: List<String>, result: A, errors: ArgumentParseErrors) {
     data class ArgumentField(val property: KMutableProperty1<A, Any?>, val argument: Argument)
 
     @Suppress("UNCHECKED_CAST")
@@ -76,7 +77,6 @@ private fun <A : CommonToolArguments> parsePreprocessedCommandLineArguments(args
         ArgumentField(property as KMutableProperty1<A, Any?>, argument)
     }
 
-    val errors = result.errors
     val visitedArgs = mutableSetOf<String>()
     var freeArgsStarted = false
 
@@ -198,7 +198,8 @@ private fun <A : CommonToolArguments> updateField(property: KMutableProperty1<A,
 /**
  * @return error message if arguments are parsed incorrectly, null otherwise
  */
-fun validateArguments(errors: ArgumentParseErrors): String? {
+fun validateArguments(errors: ArgumentParseErrors?): String? {
+    if (errors == null) return null
     if (errors.argumentWithoutValue != null) {
         return "No value passed for argument ${errors.argumentWithoutValue}"
     }

compiler/cli/src/org/jetbrains/kotlin/cli/common/CLITool.kt

@@ -118,7 +118,10 @@ abstract class CLITool<A : CommonToolArguments> {
     }
 
     private fun reportArgumentParseProblems(collector: MessageCollector, arguments: A) {
-        val errors = arguments.errors
+        reportUnsafeInternalArgumentsIfAny(arguments, collector)
+
+        val errors = arguments.errors ?: return
+
         for (flag in errors.unknownExtraFlags) {
             collector.report(STRONG_WARNING, "Flag is not supported by this version of the compiler: $flag")
         }
@@ -139,7 +142,6 @@ abstract class CLITool<A : CommonToolArguments> {
             collector.report(STRONG_WARNING, argfileError)
         }
 
-        reportUnsafeInternalArgumentsIfAny(arguments, collector)
         for (internalArgumentsError in errors.internalArgumentsParsingProblems) {
             collector.report(STRONG_WARNING, internalArgumentsError)
         }