Use __attribute__((fallthrough)) rather than magic GCC comments.
GCC added an implicit-fallthrough warning a while back, where it would complain if you had a nontrivial "case:" block that didn't end with break, return, or something like that. Clang recently added the same thing. GCC, however, would let you annotate a fall-through as intended by any of various magic "/* fall through */" comments. Clang, however, only seems to like "__attribute__((fallthrough))". Fortunately, GCC accepts that too. A previous commit in this branch defined a FALLTHROUGH macro to do the right thing if GNUC is defined; here we replace all of our "fall through" comments with uses of that macro. This is an automated commit, made with the following perl one-liner: #!/usr/bin/perl -i -p s#/\* *falls? ?thr.*?\*/#FALLTHROUGH;#i;