Added test for #3304

tests/closure/tclosureinference3304.nim

@@ -0,0 +1,15 @@
+discard """
+  output: '''@[1, 2, 5]'''
+"""
+
+import future, sequtils
+
+type
+  List[T] = ref object
+    val: T
+  
+proc foo[T](l: List[T]): seq[int] =
+  @[1,2,3,5].filter(x => x != l.val)
+
+when isMainModule:
+  echo(foo(List[int](val: 3)))