1 files changed, 3 insertions, 1 deletions
diff --git a/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala b/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala
index 006c7bd85f..68883831a2 100644
--- a/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala
+++ b/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala
@@ -95,7 +95,9 @@ trait TreeAndTypeAnalysis extends Debugging {
       // TODO: when type tags are available, we will check -- when this is implemented, can we take that into account here?
       // similar to typer.infer.approximateAbstracts
       object typeArgsToWildcardsExceptArray extends TypeMap {
-        def apply(tp: Type): Type = tp match {
+        // SI-6771 dealias would be enough today, but future proofing with the dealiasWiden.
+        // See neg/t6771b.scala for elaboration
+        def apply(tp: Type): Type = tp.dealiasWiden match {
           case TypeRef(pre, sym, args) if args.nonEmpty && (sym ne ArrayClass) =>
             TypeRef(pre, sym, args map (_ => WildcardType))
           case _ =>