Refine stacktrace printing

Author: liufengyun

compiler/src/dotty/tools/dotc/transform/init/Errors.scala

@@ -5,9 +5,9 @@ package init
 import ast.tpd._
 
 import core._
-import Decorators._
+import Decorators._, printing.SyntaxHighlighting
 import Types._, Symbols._, Contexts._
-import util.NoSourcePosition
+import util.SourcePosition
 
 import Effects._, Potentials._
 
@@ -30,19 +30,22 @@ object Errors {
 
  def stacktrace(implicit ctx: Context): String = if (trace.isEmpty) "" else " Calling trace:\n" + {
  var indentCount = 0
- var last = ""
+ var last: String = ""
  val sb = new StringBuilder
  trace.foreach { tree =>
  indentCount += 1
  val pos = tree.sourcePos
- val line = "[ " + pos.source.file.name + ":" + (pos.line + 1) + " ]"
- if (last != line)
- sb.append(
- if (pos.source.exists)
- i"${ " " * indentCount }-> ${pos.lineContent.trim}\t$line\n"
- else
- i"${tree.show}\n"
- )
+ val prefix = s"${ " " * indentCount }-> "
+ val line =
+ if pos.source.exists then
+ val loc = "[ " + pos.source.file.name + ":" + (pos.line + 1) + " ]"
+ val code = SyntaxHighlighting.highlight(pos.lineContent.trim)
+ i"$code\t$loc"
+ else
+ tree.show
+
+ if (last != line) sb.append(prefix + line + "\n")
+
  last = line
  }
  sb.toString