SI-10120 ReplReporter handles message indent

Instead of indenting source code to make messages
align on output, let the reporter add indentation,
only if the source is the console (and not a pastie
or a loaded file).

Previously, syntax errors were not indented.

```
$ skala
Welcome to Scala 2.12.2-20170108-010722-939abf1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_111).
Type in expressions for evaluation. Or try :help.

scala> 'abc'
<console>:1: error: unclosed character literal (or use " for string literal "abc")
       'abc'
           ^

scala> :quit
$ scala
Welcome to Scala 2.12.1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_111).
Type in expressions for evaluation. Or try :help.

scala> 'abc'
<console>:1: error: unclosed character literal
'abc'
    ^
```

3 files changed, 22 insertions, 53 deletions

diff --git a/src/repl/scala/tools/nsc/interpreter/Formatting.scala b/src/repl/scala/tools/nsc/interpreter/Formatting.scala
deleted file mode 100644
index 4a9548730a..0000000000
--- a/src/repl/scala/tools/nsc/interpreter/Formatting.scala
+++ /dev/null
@@ -1,35 +0,0 @@
-/* NSC -- new Scala compiler
- * Copyright 2005-2013 LAMP/EPFL
- * @author Paul Phillips
- */
-
-package scala.tools.nsc
-package interpreter
-
-import util.stringFromWriter
-
-class Formatting(indent: Int) {
-
-  private val indentation = " " * indent
-
-  private def indenting(code: String): Boolean = {
-    /** Heuristic to avoid indenting and thereby corrupting """-strings and XML literals. */
-    val tokens = List("\"\"\"", "</", "/>")
-    val noIndent = (code contains "\n") && (tokens exists code.contains)
-
-    !noIndent
-  }
-  /** Indent some code by the width of the scala> prompt.
-   *  This way, compiler error messages read better.
-   */
-  def indentCode(code: String) = stringFromWriter(str =>
-    for (line <- code.lines) {
-      if (indenting(code)) str print indentation
-      str println line
-      str.flush()
-    }
-  )
-}
-object Formatting {
-  def forPrompt(prompt: String) = new Formatting(prompt.lines.toList.last.length)
-}
diff --git a/src/repl/scala/tools/nsc/interpreter/IMain.scala b/src/repl/scala/tools/nsc/interpreter/IMain.scala
index 980d12f9b8..453c2eb678 100644
--- a/src/repl/scala/tools/nsc/interpreter/IMain.scala
+++ b/src/repl/scala/tools/nsc/interpreter/IMain.scala
@@ -111,11 +111,8 @@ class IMain(initialSettings: Settings, protected val out: JPrintWriter) extends
     try body finally label = saved
   }
 
-  // the expanded prompt but without color escapes and without leading newline, for purposes of indenting
-  lazy val formatting = Formatting.forPrompt(replProps.promptText)
   lazy val reporter: ReplReporter = new ReplReporter(this)
 
-  import formatting.indentCode
   import reporter.{ printMessage, printUntruncatedMessage }
 
   // This exists mostly because using the reporter too early leads to deadlock.
@@ -867,8 +864,8 @@ class IMain(initialSettings: Settings, protected val out: JPrintWriter) extends
         |${preambleHeader format lineRep.readName}
         |${envLines mkString ("  ", ";\n  ", ";\n")}
         |$importsPreamble
-        |${indentCode(toCompute)}""".stripMargin
-      def preambleLength = preamble.length - toCompute.length - 1
+        |${toCompute}""".stripMargin
+      def preambleLength = preamble.length - toCompute.length
 
       val generate = (m: MemberHandler) => m extraCodeToEvaluate Request.this
 
diff --git a/src/repl/scala/tools/nsc/interpreter/ReplReporter.scala b/src/repl/scala/tools/nsc/interpreter/ReplReporter.scala
index 3a0b69f41e..b01d242d44 100644
--- a/src/repl/scala/tools/nsc/interpreter/ReplReporter.scala
+++ b/src/repl/scala/tools/nsc/interpreter/ReplReporter.scala
@@ -9,7 +9,7 @@ package interpreter
 import reporters._
 import IMain._
 
-import scala.reflect.internal.util.Position
+import scala.reflect.internal.util.{OffsetPosition, Position}
 
 /** Like ReplGlobal, a layer for ensuring extra functionality.
  */
@@ -40,14 +40,25 @@ class ReplReporter(intp: IMain) extends ConsoleReporter(intp.settings, Console.i
     case INFO    => RESET
   }
 
+  private val promptLength = replProps.promptText.lines.toList.last.length
+  private val indentation  = " " * promptLength
+
+  // colorized console labels
+  override protected def clabel(severity: Severity): String = {
+    val label0 = super.clabel(severity)
+    if (replProps.colorOk) s"${severityColor(severity)}${label0}${RESET}" else label0
+  }
+
+  // shift indentation for source text entered at prompt
   override def print(pos: Position, msg: String, severity: Severity) {
-    val prefix = (
-      if (replProps.colorOk)
-        severityColor(severity) + clabel(severity) + RESET
-      else
-        clabel(severity)
-    )
-    printMessage(pos, prefix + msg)
+    val adjusted =
+      if (pos.source.file.name == "<console>")
+        new OffsetPosition(pos.source, pos.offset.getOrElse(0)) {
+          override def lineContent = s"${indentation}${super.lineContent}"
+          override def lineCaret   = s"${indentation}${super.lineCaret}"
+        }
+      else pos
+    super.print(adjusted, msg, severity)
   }
 
   override def printMessage(msg: String) {
@@ -63,12 +74,8 @@ class ReplReporter(intp: IMain) extends ConsoleReporter(intp.settings, Console.i
     else Console.println("[init] " + msg)
   }
 
-  override def displayPrompt() {
-    if (intp.totalSilence) ()
-    else super.displayPrompt()
-  }
+  override def displayPrompt() = if (!intp.totalSilence) super.displayPrompt()
 
   override def rerunWithDetails(setting: reflect.internal.settings.MutableSettings#Setting, name: String) =
     s"; for details, enable `:setting $name' or `:replay $name'"
-
 }