Move GADT check to typeTyped

Author: felixmulder

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

@@ -448,6 +448,10 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
                 return typed(untpd.Apply(untpd.TypedSplice(arg), tree.expr), pt)
               case _ =>
             }
+          case tref: TypeRef if tref.symbol.isClass && !ctx.isAfterTyper =>
+            val setBefore = ctx.mode is Mode.GADTflexible
+            tpt1.tpe.<:<(pt)(ctx.addMode(Mode.GADTflexible))
+            if (!setBefore) ctx.retractMode(Mode.GADTflexible)
           case _ =>
         }
         ascription(tpt1, isWildcard = true)
@@ -1653,10 +1657,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
         case SearchSuccess(inferred, _, _) =>
           adapt(inferred, pt)
         case failure: SearchFailure =>
-          if (
-            pt.isInstanceOf[ProtoType] && !failure.isInstanceOf[AmbiguousImplicits] ||
-            tree.tpe.<:<(pt)(ctx.addMode(Mode.GADTflexible))
-          ) tree
+          if (pt.isInstanceOf[ProtoType] && !failure.isInstanceOf[AmbiguousImplicits]) tree
           else err.typeMismatch(tree, pt, failure)
       }
     }