add test case for #20289 (#21180)

tests/misc/t20289.nim

@@ -0,0 +1,15 @@
+discard """
+  action: reject
+"""
+
+type E[T] = object
+  v: T
+
+template j[T](R: type E[T], x: untyped): R = R(v: x)
+template d[T](O: type E, v: T): E[T] = E[T].j(v)
+
+proc w[T](): E[T] =
+  template r(k: int): auto = default(T)
+  E.d r
+
+discard w[int]()