#![feature(box_patterns)] struct HTMLImageData { image: Option, } struct ElementData { kind: Box, } enum ElementKind { HTMLImageElement(HTMLImageData), } enum NodeKind { Element(ElementData), } struct NodeData { kind: Box, } fn main() { let mut id = HTMLImageData { image: None }; let ed = ElementData { kind: Box::new(ElementKind::HTMLImageElement(id)) }; let n = NodeData { kind: Box::new(NodeKind::Element(ed)) }; match n.kind { box NodeKind::Element(ed) => match ed.kind { //~^ ERROR non-exhaustive patterns //~| NOTE the matched value is of type //~| NOTE match arms with guards don't count towards exhaustivity //~| NOTE pattern `box _` not covered //~| NOTE `Box` defined here box ElementKind::HTMLImageElement(ref d) if d.image.is_some() => true, }, }; }