SI-4829 the :load command now fails claiming a file does not exist if the command ends with a space

The :load command now tries to be smart by detecting the presence of trailing spaces that might be insignificant.

On certain file systems, files with trailing whitespaces are permitted which is why we don't naievely trim the argument.

Author: jedesah

src/compiler/scala/tools/nsc/interpreter/ILoop.scala

@@ -11,7 +11,7 @@ import java.io.{ BufferedReader, FileReader }
 import java.util.concurrent.locks.ReentrantLock
 import scala.sys.process.Process
 import session._
-import scala.tools.util.{ Signallable, Javap }
+import scala.tools.util.{ Signallable, Javap, StringOps }
 import scala.annotation.tailrec
 import scala.collection.mutable.ListBuffer
 import scala.concurrent.ops
@@ -595,12 +595,13 @@ class ILoop(in0: Option[BufferedReader], protected val out: JPrintWriter)
     val f = File(filename)
 
     if (f.exists) action(f)
-    else echo("That file does not exist")
+    else echo("\"" + filename + "\" does not appear to exist")
   }
 
   def loadCommand(arg: String) = {
+    val smartArg = if (File(arg).exists) arg else arg.trim
     var shouldReplay: Option[String] = None
-    withFile(arg)(f => {
+    withFile(smartArg)(f => {
       interpretAllFrom(f)
       shouldReplay = Some(":load " + arg)
     })
@@ -641,9 +642,10 @@ class ILoop(in0: Option[BufferedReader], protected val out: JPrintWriter)
     * if any. */
   def command(line: String): Result = {
     if (line startsWith ":") {
-      val cmd = line.tail takeWhile (x => !x.isWhitespace)
+      val lineNoColon = line.tail
+      val (cmd, arg) = StringOps.splitLeft(lineNoColon, ' ').getOrElse((lineNoColon, ""))
       uniqueCommand(cmd) match {
-        case Some(lc) => lc(line.tail stripPrefix cmd dropWhile (_.isWhitespace))
+        case Some(lc) => lc(arg)
         case _        => ambiguousError(cmd)
       }
     }

src/compiler/scala/tools/util/StringOps.scala

@@ -54,6 +54,10 @@ trait StringOps {
     if (idx == -1) None
     else Some(str take idx, str drop (if (doDropIndex) idx + 1 else idx))
 
+  def splitLeft(str: String, ch: Char): Option[(String, String)] = {
+    splitAt(str, str.indexOf(' '), true)
+  }
+
   /** Returns a string meaning "n elements".
    *
    *  @param n        ...