Compare :
/**
some file
*/
with
/*
some file
*/

In the first case, font-lock-doc-face is used, in the second
font-lock-comment-face is.

The first example fontifies with doc-face only if there is just "/**" :
"/*", "/** " (with a space) or "/***", for instance, use the standard
comment-face.

This is using emacs 23.0.94.1, and was reproduced on emacs22 as well. C++
and obj-C aren't affected, and java also shows this behavior on "/***"" and
"/** "/

This behavior is certainly unexpected : I expect all comments to be
fontified with the same face. Am I right in thinking it's a bug ?

Antoine