Support argfiles in CLI with "@argfile"

#KT-24613 Fixed

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

@@ -10,7 +10,8 @@ import java.io.FileNotFoundException
 import java.io.IOException
 import java.io.Reader
 
-private const val EXPERIMENTAL_ARGFILE_ARGUMENT = "-Xargfile"
+const val ARGFILE_ARGUMENT = "@"
+private const val EXPERIMENTAL_ARGFILE_ARGUMENT = "-Xargfile="
 
 private const val SINGLE_QUOTE = '\''
 private const val DOUBLE_QUOTE = '"'
@@ -24,11 +25,16 @@ private const val NEWLINE = '\n'
  * will be used instead of actual passed arguments.
  */
 internal fun preprocessCommandLineArguments(args: List<String>, errors: ArgumentParseErrors): List<String> =
-    args.flatMap {
-        if (it.isArgumentForArgfile)
-            File(it.argfilePath).expand(errors)
-        else
-            listOf(it)
+    args.flatMap { arg ->
+        if (arg.isArgfileArgument) {
+            File(arg.argfilePath).expand(errors)
+        } else if (arg.isDeprecatedArgfileArgument) {
+            errors.deprecatedArguments[EXPERIMENTAL_ARGFILE_ARGUMENT] = ARGFILE_ARGUMENT
+
+            File(arg.deprecatedArgfilePath).expand(errors)
+        } else {
+            listOf(arg)
+        }
     }
 
 private fun File.expand(errors: ArgumentParseErrors): List<String> {
@@ -80,9 +86,13 @@ private fun Reader.nextChar(): Char? =
     read().takeUnless { it == -1 }?.toChar()
 
 private val String.argfilePath: String
-    get() = removePrefix("$EXPERIMENTAL_ARGFILE_ARGUMENT=")
+    get() = removePrefix(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("$EXPERIMENTAL_ARGFILE_ARGUMENT=")
+private val String.isArgfileArgument: Boolean
+    get() = startsWith(ARGFILE_ARGUMENT)
+
+private val String.deprecatedArgfilePath: String
+    get() = removePrefix(EXPERIMENTAL_ARGFILE_ARGUMENT)
+
+private val String.isDeprecatedArgfileArgument: Boolean
+    get() = startsWith(EXPERIMENTAL_ARGFILE_ARGUMENT)