Make DiffUtil's rendering readable in logs

Author: felixmulder

compiler/src/dotty/tools/dotc/reporting/MessageRendering.scala

@@ -21,7 +21,7 @@ trait MessageRendering {
     * @return string stripped of ANSI escape codes
     */
   def stripColor(str: String): String =
-    str.replaceAll("\u001B\\[[;\\d]*m", "")
+    str.replaceAll("\u001b\\[.*?m", "")
 
   /** When inlining a method call, if there's an error we'd like to get the
     * outer context and the `pos` at which the call was inlined.

compiler/src/dotty/tools/dotc/util/DiffUtil.scala

@@ -58,8 +58,25 @@ object DiffUtil {
     (fnd, exp, totalChange.toDouble / (expected.length + found.length))
   }
 
-  def mkColoredCodeDiff(code: String, lastCode: String, printDiffDel: Boolean): String = {
+  def mkColoredLineDiff(expected: String, actual: String): String = {
+    val tokens = splitTokens(expected, Nil).toArray
+    val lastTokens = splitTokens(actual, Nil).toArray
+
+    val diff = hirschberg(lastTokens, tokens)
 
+    "  |SOF\n" + diff.collect {
+      case Unmodified(str) =>
+        "  |" + str
+      case Inserted(str) =>
+        ADDITION_COLOR + "e |" + str + ANSI_DEFAULT
+      case Modified(old, str) =>
+        DELETION_COLOR + "a |" + old + "\ne |" + ADDITION_COLOR + str + ANSI_DEFAULT
+      case Deleted(str) =>
+        DELETION_COLOR + "\na |" + str + ANSI_DEFAULT
+    }.mkString + "\n  |EOF"
+  }
+
+  def mkColoredCodeDiff(code: String, lastCode: String, printDiffDel: Boolean): String = {
     val tokens = splitTokens(code, Nil).toArray
     val lastTokens = splitTokens(lastCode, Nil).toArray
 

compiler/test/dotty/tools/dotc/ParallelTesting.scala

@@ -456,7 +456,7 @@ trait ParallelTesting { self =>
       if (outputLines.length != checkLines.length || !linesMatch) {
         // Print diff to files and summary:
         val diff = outputLines.zip(checkLines).map { case (act, exp) =>
-          DiffUtil.mkColoredCodeDiff(exp, act, true)
+          DiffUtil.mkColoredLineDiff(exp, act)
         }.mkString("\n")
         val msg = s"\nOutput from run test '$checkFile' did not match expected, output:\n$diff\n"
         echo(msg)