It's unlikely that the man in the photo is Charlie Rivel, who was a star in his own right at the time and, as my friend, Dominique Dugros, pointed out, "would not have been waiting for CC outside a French cabaret, just greeting him without being presented." This makes perfect sense. Thanks to Dominique for also identifying Harry Crocker in the photo.
Below are some real photos of Charlie Rivel (source: fauxcharlot.blogspot.com).
Read more about Rivel here.