Also catch TypeErrors in all transforms

Once we are at it, let's try to bullet-proof everything.

Author: odersky

compiler/src/dotty/tools/dotc/core/TypeErrors.scala

@@ -66,6 +66,7 @@ class RecursionOverflow(val op: String, details: => String, previous: Throwable,
     val mostCommon = recursions.groupBy(_.op).toList.maxBy(_._2.map(_.weight).sum)._2.reverse
     s"""Recursion limit exceeded.
        |Maybe there is an illegal cyclic reference?
+       |If that's not the case, you could also try to increase the stacksize using the -Xss JVM option.
        |A recurring operation is (inner to outer):
        |${opsString(mostCommon)}""".stripMargin
   }

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

@@ -46,22 +46,27 @@ abstract class MacroTransform extends Phase {
       flatten(trees.mapconserve(transformStat(_)))
     }
 
-    override def transform(tree: Tree)(implicit ctx: Context): Tree = {
-      tree match {
-        case EmptyValDef =>
+    override def transform(tree: Tree)(implicit ctx: Context): Tree =
+      try
+        tree match {
+          case EmptyValDef =>
+            tree
+          case _: PackageDef | _: MemberDef =>
+            super.transform(tree)(localCtx(tree))
+          case impl @ Template(constr, parents, self, _) =>
+            cpy.Template(tree)(
+              transformSub(constr),
+              transform(parents)(ctx.superCallContext),
+              transformSelf(self),
+              transformStats(impl.body, tree.symbol))
+          case _ =>
+            super.transform(tree)
+        }
+      catch {
+        case ex: TypeError =>
+          ctx.error(ex.toMessage, tree.pos)
           tree
-        case _: PackageDef | _: MemberDef =>
-          super.transform(tree)(localCtx(tree))
-        case impl @ Template(constr, parents, self, _) =>
-          cpy.Template(tree)(
-            transformSub(constr),
-            transform(parents)(ctx.superCallContext),
-            transformSelf(self),
-            transformStats(impl.body, tree.symbol))
-        case _ =>
-          super.transform(tree)
       }
-    }
 
     def transformSelf(vd: ValDef)(implicit ctx: Context) =
       cpy.ValDef(vd)(tpt = transform(vd.tpt))

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

@@ -193,7 +193,13 @@ class MegaPhase(val miniPhases: Array[MiniPhase]) extends Phase {
       case tree: Alternative => goAlternative(tree, start)
       case tree => goOther(tree, start)
     }
-    if (tree.isInstanceOf[NameTree]) goNamed(tree, start) else goUnnamed(tree, start)
+    try
+      if (tree.isInstanceOf[NameTree]) goNamed(tree, start) else goUnnamed(tree, start)
+    catch {
+      case ex: TypeError =>
+        ctx.error(ex.toMessage, tree.pos)
+        tree
+    }
   }
 
   /** Transform full tree using all phases in this group that have idxInGroup >= start */