{"ast_node_type":"variable","tokens":[{"end":81,"kind":"keyword","start":0,"text":"if"}]}
        if let (Some(CtorKind::Fn), PatKind::Struct(qpath, field_patterns, ..)) =
        // be invalid identifiers (for example, Foo { 0, 1 }).
            (variant.ctor_kind(), &pat.kind)