Support -Xargfile in all scenarios; refactor & prettify code

Perform command line argument preprocessing in the beginning of
parseCommandLineArguments, so that argfiles are expanded in all
scenarios, not just when the compiler is invoked via
K2{JVM,JS}Compiler.exec

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

@@ -54,11 +54,16 @@ data class ArgumentParseErrors(
 
     var argumentWithoutValue: String? = null,
 
-    val argfileErrors: MutableList<String> = SmartList<String>()
+    val argfileErrors: MutableList<String> = SmartList()
 )
 
 // 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)
+}
+
+private fun <A : CommonToolArguments> parsePreprocessedCommandLineArguments(args: List<String>, result: A) {
     data class ArgumentField(val property: KMutableProperty1<A, Any?>, val argument: Argument)
 
     @Suppress("UNCHECKED_CAST")

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

@@ -5,39 +5,42 @@
 
 package org.jetbrains.kotlin.cli.common.arguments
 
-import java.io.*
-import java.nio.charset.StandardCharsets
+import java.io.File
+import java.io.FileNotFoundException
+import java.io.IOException
+import java.io.Reader
 
-private val experimentalArgfileArgument = "-Xargfile"
-private val QUOTATION_MARK = '"'
-private val BACKSLASH = '\\'
-private val WHITESPACE = ' '
-private val NEWLINE = '\n'
+private const val EXPERIMENTAL_ARGFILE_ARGUMENT = "-Xargfile"
+
+private const val QUOTATION_MARK = '"'
+private const val BACKSLASH = '\\'
+private const val WHITESPACE = ' '
+private const val NEWLINE = '\n'
 
 /**
  * Performs initial preprocessing of arguments, passed to the compiler.
  * This is done prior to *any* arguments parsing, and result of preprocessing
  * will be used instead of actual passed arguments.
  */
-fun <A : CommonToolArguments> preprocessCommandLineArguments(args: List<String>, result: A): List<String> =
+internal fun preprocessCommandLineArguments(args: List<String>, errors: ArgumentParseErrors): List<String> =
     args.flatMap {
         if (it.isArgumentForArgfile)
-            File(it.argfilePath).expand(result)
+            File(it.argfilePath).expand(errors)
         else
             listOf(it)
     }
 
-private fun <A : CommonToolArguments> File.expand(result: A): List<String> {
+private fun File.expand(errors: ArgumentParseErrors): List<String> {
     return try {
         bufferedReader(Charsets.UTF_8).use {
             generateSequence { it.parseNextArgument() }.toList()
         }
     } catch (e: FileNotFoundException) {
         // Process FNFE separately to render absolutePath in error message
-        result.errors.argfileErrors += "Argfile not found: $absolutePath"
+        errors.argfileErrors += "Argfile not found: $absolutePath"
         emptyList()
     } catch (e: IOException) {
-        result.errors.argfileErrors += "Error while reading argfile: $e"
+        errors.argfileErrors += "Error while reading argfile: $e"
         emptyList()
     }
 }
@@ -69,9 +72,9 @@ private fun Reader.consumeRestOfEscapedSequence(sb: StringBuilder) {
 }
 
 private val String.argfilePath: String
-    get() = removePrefix("$experimentalArgfileArgument=")
+    get() = removePrefix("$EXPERIMENTAL_ARGFILE_ARGUMENT=")
 
 // Note that currently we use only experimental syntax for passing argfiles
 // In 1.3 we can support also javac-like syntax `@argfile`
 private val String.isArgumentForArgfile: Boolean
-    get() = startsWith("$experimentalArgfileArgument=")
+    get() = startsWith("$EXPERIMENTAL_ARGFILE_ARGUMENT=")