Roald Dahl didn't write the screenplay, he wrote the book the movie is based on.
edit: Correction, he did write it for the 1971 movie. Oops.
(I agree, and it's making me sad to see all the memorials on Twitter with stills from that film... Wilder did vastly better work)
Roald Dahl didn't write the screenplay, he wrote the book the movie is based on.
edit: Correction, he did write it for the 1971 movie. Oops.