report: Add a Y-flag to disable enriched error messages

Author: dwijnand

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -421,6 +421,7 @@ private sealed trait YSettings:
   val YshowVarBounds: Setting[Boolean] = BooleanSetting("-Yshow-var-bounds", "Print type variables with their bounds.")
 
   val YnoDecodeStacktraces: Setting[Boolean] = BooleanSetting("-Yno-decode-stacktraces", "Show raw StackOverflow stacktraces, instead of decoding them into triggering operations.")
+  val YnoEnrichErrorMessages: Setting[Boolean] = BooleanSetting("-Yno-enrich-error-messages", "Show raw error messages, instead of enriching them with contextual information.")
 
   val Yinstrument: Setting[Boolean] = BooleanSetting("-Yinstrument", "Add instrumentation code that counts allocations and closure creations.")
   val YinstrumentDefs: Setting[Boolean] = BooleanSetting("-Yinstrument-defs", "Add instrumentation code that counts method calls; needs -Yinstrument to be set, too.")

compiler/src/dotty/tools/dotc/report.scala

@@ -132,7 +132,13 @@ object report:
   private object messageRendering extends MessageRendering
 
   // Should only be called from Run#enrichErrorMessage.
-  def enrichErrorMessage(errorMessage: String)(using Context): String = try {
+  def enrichErrorMessage(errorMessage: String)(using Context): String =
+    if ctx.settings.YnoEnrichErrorMessages.value then errorMessage
+    else try enrichErrorMessage1(errorMessage)
+    catch case _: Throwable => errorMessage // don't introduce new errors trying to report errors, so swallow exceptions
+
+  private def enrichErrorMessage1(errorMessage: String)(using Context): String = {
+    import untpd.*, config.Settings.*
     def formatExplain(pairs: List[(String, Any)]) = pairs.map((k, v) => f"$k%20s: $v").mkString("\n")
 
     val settings = ctx.settings.userSetSettings(ctx.settingsState).sortBy(_.name)
@@ -155,5 +161,5 @@ object report:
        |
        |$info1
        |""".stripMargin
-  } catch case _: Throwable => errorMessage // don't introduce new errors trying to report errors, so swallow exceptions
+  }
 end report