Author: Julia Lawall <julia@diku.dk> At the point of the print, dev is NULL. A simplified version of the semantic match that finds this problem is as follows: (http://coccinelle.lip6.fr/) // @r exists@ expression E,E1; identifier f; statement S1,S2,S3; @@ if ((E == NULL && …) || …) { … when != if (…) S1 else S2 …