Rework -Xprint-args to continue compiler and allow file output

Author: retronym

src/compiler/scala/tools/nsc/CompilerCommand.scala

@@ -107,13 +107,8 @@ class CompilerCommand(arguments: List[String], val settings: Settings) {
       if (debug) "\n" + global.phaseFlagDescriptions else ""
     )
     else if (genPhaseGraph.isSetByUser) {
-      val components = global.phaseNames  // global.phaseDescriptors // one initializes
+      val components = global.phaseNames // global.phaseDescriptors // one initializes
       s"Phase graph of ${components.size} components output to ${genPhaseGraph.value}*.dot."
-    } else if (printArgs.value) {
-      s"""
-         |${recreateArgs.mkString("\n")}
-         |${files.mkString("\n")}
-        """.stripMargin
     }
     else allSettings.filter(_.isHelping).map(_.help).mkString("\n\n")
   }

src/compiler/scala/tools/nsc/Global.scala

@@ -1438,11 +1438,25 @@ class Global(var currentSettings: Settings, reporter0: LegacyReporter)
     /** Caching member symbols that are def-s in Definitions because they might change from Run to Run. */
     val runDefinitions: definitions.RunDefinitions = new definitions.RunDefinitions
 
+    private def printArgs(sources: List[SourceFile]): Unit = {
+      val argsFile = (settings.recreateArgs ::: sources.map(_.file.absolute.toString())).mkString("", "\n", "\n")
+      settings.printArgs.value match {
+        case "-" =>
+          reporter.echo(argsFile)
+        case pathString =>
+          import java.nio.file._
+          val path = Paths.get(pathString)
+          Files.write(path, argsFile.getBytes(Charset.forName("UTF-8")))
+          reporter.echo("Compiler arguments written to: " + path)
+      }
+    }
+
     /** Compile list of source files,
      *  unless there is a problem already,
      *  such as a plugin was passed a bad option.
      */
     def compileSources(sources: List[SourceFile]): Unit = if (!reporter.hasErrors) {
+      printArgs(sources)
 
       def checkDeprecations() = {
         warnDeprecatedAndConflictingSettings()

src/compiler/scala/tools/nsc/settings/ScalaSettings.scala

@@ -43,7 +43,7 @@ trait ScalaSettings extends AbsScalaSettings
   protected def futureSettings = List[BooleanSetting]()
 
   /** If any of these settings is enabled, the compiler should print a message and exit.  */
-  def infoSettings = List[Setting](version, help, Xhelp, Yhelp, showPlugins, showPhases, genPhaseGraph, printArgs)
+  def infoSettings = List[Setting](version, help, Xhelp, Yhelp, showPlugins, showPhases, genPhaseGraph)
 
   /** Is an info setting set? Any -option:help? */
   def isInfo = infoSettings.exists(_.isSetByUser) || allSettings.exists(_.isHelping)
@@ -143,7 +143,7 @@ trait ScalaSettings extends AbsScalaSettings
   val Xprint             = PhasesSetting       ("-Xprint", "Print out program after")
   val Xprintpos          = BooleanSetting      ("-Xprint-pos", "Print tree positions, as offsets.")
   val printtypes         = BooleanSetting      ("-Xprint-types", "Print tree types (debugging option).")
-  val printArgs          = BooleanSetting      ("-Xprint-args", "Print all compiler arguments and exit.")
+  val printArgs          = StringSetting       ("-Xprint-args", "<file>", "Print all compiler arguments to <file>. Use - to echo to the reporter.", "-")
   val prompt             = BooleanSetting      ("-Xprompt", "Display a prompt after each error (debugging option).")
   val resident           = BooleanSetting      ("-Xresident", "Compiler stays resident: read source filenames from standard input.")
   val script             = StringSetting       ("-Xscript", "object", "Treat the source file as a script and wrap it in a main method.", "")