Add -Ydebug-type-error to print the stack when a TypeError is caught

Author: smarter

compiler/src/dotty/tools/dotc/ast/TreeMapWithImplicits.scala

@@ -119,7 +119,7 @@ class TreeMapWithImplicits extends tpd.TreeMap {
     }
     catch {
       case ex: TypeError =>
-        ctx.error(ex.toMessage, tree.sourcePos)
+        ctx.error(ex, tree.sourcePos)
         tree
     }
   }

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

@@ -103,6 +103,7 @@ class ScalaSettings extends Settings.SettingGroup {
   val YdebugNames: Setting[Boolean] = BooleanSetting("-Ydebug-names", "Show internal representation of names")
   val YdebugPos: Setting[Boolean] = BooleanSetting("-Ydebug-pos", "Show full source positions including spans")
   val YdebugTreeWithId: Setting[Int] = IntSetting("-Ydebug-tree-with-id", "Print the stack trace when the tree with the given id is created", Int.MinValue)
+  val YdebugTypeError: Setting[Boolean] = BooleanSetting("-Ydebug-type-error", "Print the stack trace when a TypeError is caught", false)
   val YtermConflict: Setting[String] = ChoiceSetting("-Yresolve-term-conflict", "strategy", "Resolve term conflicts", List("package", "object", "error"), "error")
   val Ylog: Setting[List[String]] = PhasesSetting("-Ylog", "Log operations during")
   val YemitTastyInClass: Setting[Boolean] = BooleanSetting("-Yemit-tasty-in-class", "Generate tasty in the .class file and add an empty *.hasTasty file.")

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

@@ -5,6 +5,7 @@ package reporting
 import scala.annotation.internal.sharable
 
 import core.Contexts._
+import core.TypeError
 import util.{SourcePosition, NoSourcePosition}
 import core.Decorators.PhaseListDecorator
 import collection.mutable
@@ -136,6 +137,12 @@ trait Reporting { this: Context =>
     reporter.report(if (sticky) new StickyError(msg, fullPos) else new Error(msg, fullPos))
   }
 
+  def error(ex: TypeError, pos: SourcePosition): Unit = {
+    error(ex.toMessage, pos, sticky = true)
+    if (ctx.settings.YdebugTypeError.value)
+      ex.printStackTrace
+  }
+
   def errorOrMigrationWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
     if (ctx.scala2Mode) migrationWarning(msg, pos) else error(msg, pos)
 

compiler/src/dotty/tools/dotc/sbt/ExtractAPI.scala

@@ -247,7 +247,7 @@ private class ExtractAPICollector(implicit val ctx: Context) extends ThunkHolder
           case ex: TypeError =>
             // See neg/i1750a for an example where a cyclic error can arise.
             // The root cause in this example is an illegal "override" of an inner trait
-            ctx.error(ex.toMessage, csym.sourcePos, sticky = true)
+            ctx.error(ex, csym.sourcePos)
             defn.ObjectType :: Nil
         }
       if (ValueClasses.isDerivedValueClass(csym)) {

compiler/src/dotty/tools/dotc/transform/MacroTransform.scala

@@ -64,7 +64,7 @@ abstract class MacroTransform extends Phase {
         }
       catch {
         case ex: TypeError =>
-          ctx.error(ex.toMessage, tree.sourcePos, sticky = true)
+          ctx.error(ex, tree.sourcePos)
           tree
       }
 

compiler/src/dotty/tools/dotc/transform/MegaPhase.scala

@@ -170,7 +170,7 @@ class MegaPhase(val miniPhases: Array[MiniPhase]) extends Phase {
         }
       catch {
         case ex: TypeError =>
-          ctx.error(ex.toMessage, tree.sourcePos)
+          ctx.error(ex, tree.sourcePos)
           tree
       }
     def goUnnamed(tree: Tree, start: Int) =
@@ -205,7 +205,7 @@ class MegaPhase(val miniPhases: Array[MiniPhase]) extends Phase {
         }
       catch {
         case ex: TypeError =>
-          ctx.error(ex.toMessage, tree.sourcePos, sticky = true)
+          ctx.error(ex, tree.sourcePos)
           tree
       }
     if (tree.isInstanceOf[NameTree]) goNamed(tree, start) else goUnnamed(tree, start)

compiler/src/dotty/tools/dotc/transform/OverridingPairs.scala

@@ -134,7 +134,7 @@ object OverridingPairs {
             case ex: TypeError =>
               // See neg/i1750a for an example where a cyclic error can arise.
               // The root cause in this example is an illegal "override" of an inner trait
-              ctx.error(ex.toMessage, base.sourcePos, sticky = true)
+              ctx.error(ex, base.sourcePos)
           }
         } else {
           curEntry = curEntry.prev

compiler/src/dotty/tools/dotc/typer/ErrorReporting.scala

@@ -16,17 +16,25 @@ object ErrorReporting {
 
   import tpd._
 
-  def errorTree(tree: untpd.Tree, msg: => Message, pos: SourcePosition, sticky: Boolean = false)(implicit ctx: Context): tpd.Tree =
-    tree.withType(errorType(msg, pos, sticky))
+  def errorTree(tree: untpd.Tree, msg: => Message, pos: SourcePosition)(implicit ctx: Context): tpd.Tree =
+    tree.withType(errorType(msg, pos))
 
   def errorTree(tree: untpd.Tree, msg: => Message)(implicit ctx: Context): tpd.Tree =
     errorTree(tree, msg, tree.sourcePos)
 
-  def errorType(msg: => Message, pos: SourcePosition, sticky: Boolean = false)(implicit ctx: Context): ErrorType = {
-    ctx.error(msg, pos, sticky)
+  def errorTree(tree: untpd.Tree, msg: TypeError, pos: SourcePosition)(implicit ctx: Context): tpd.Tree =
+    tree.withType(errorType(msg, pos))
+
+  def errorType(msg: => Message, pos: SourcePosition)(implicit ctx: Context): ErrorType = {
+    ctx.error(msg, pos)
     ErrorType(msg)
   }
 
+  def errorType(ex: TypeError, pos: SourcePosition)(implicit ctx: Context): ErrorType = {
+    ctx.error(ex, pos)
+    ErrorType(ex.toMessage)
+  }
+
   def wrongNumberOfTypeArgs(fntpe: Type, expectedArgs: List[ParamInfo], actual: List[untpd.Tree], pos: SourcePosition)(implicit ctx: Context): ErrorType =
     errorType(WrongNumberOfTypeArgs(fntpe, expectedArgs, actual)(ctx), pos)
 

compiler/src/dotty/tools/dotc/typer/RefChecks.scala

@@ -971,7 +971,7 @@ class RefChecks extends MiniPhase { thisPhase =>
     tree
   } catch {
     case ex: TypeError =>
-      ctx.error(ex.toMessage, tree.sourcePos, sticky = true)
+      ctx.error(ex, tree.sourcePos)
       tree
   }
 

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -2419,7 +2419,7 @@ class Typer extends Namer
         try adapt(typedUnadapted(tree, pt, locked), pt, locked)
         catch {
           case ex: TypeError =>
-            errorTree(tree, ex.toMessage, tree.sourcePos.focus, sticky = true)
+            errorTree(tree, ex, tree.sourcePos.focus)
             // This uses tree.span.focus instead of the default tree.span, because:
             // - since tree can be a top-level definition, tree.span can point to the whole definition
             // - that would in turn hide all other type errors inside tree.
@@ -3195,7 +3195,7 @@ class Typer extends Namer
               }
             }
             catch {
-              case ex: TypeError => errorTree(tree, ex.toMessage, tree.sourcePos, sticky = true)
+              case ex: TypeError => errorTree(tree, ex, tree.sourcePos)
             }
           val nestedCtx = ctx.fresh.setNewTyperState()
           val app = tryExtension(nestedCtx)