On Thu, Feb 02, 2017 at 03:08:09PM -0800, Ben Pfaff wrote: > On Thu, Feb 02, 2017 at 02:55:03PM -0800, Shu Shen wrote: > > On Tue, Jan 31, 2017 at 10:45:31AM -0800, Ben Pfaff wrote: > > > By my count, vlan_tci_to_pcp() is used in printf-like format > > > specifiers in 7 places in the tree. Before this patch, it is used > > > with the following format specifiers: > > > > > > %d 3 times %x 1 time PRIu8 1 time PRIx8 1 time > > > > > > Both %d and %x are obviously correct, portable format specifiers for > > > int, which is the return type of vlan_tci_to_pcp(). I contend that > > > PRIu8 and PRIx8 should be acceptable too because the integer > > > promotions convert uint8_t to int anyway. > > The problem is that PRIu8 and PRIx8 the specifiers are not promoted to > > 'u' and 'x' respectively on macOS. > > > > For example, for PRIu*, on Mac OS, /usr/include/inttypes.h: > > > > # define __PRI_8_LENGTH_MODIFIER__ "hh" > > # define __PRI_64_LENGTH_MODIFIER__ "ll" > > # define PRIu8 __PRI_8_LENGTH_MODIFIER__ "u" > > # define PRIu16 "hu" > > # define PRIu32 "lu" > > # define PRIu64 __PRI_64_LENGTH_MODIFIER__ "u" > > > > While on Linux/glibc, /usr/include/inttypes.h: > > > > # define PRIu8 "u" > > # define PRIu16 "u" > > # define PRIu32 "u" > > # define PRIu64 __PRI64_PREFIX "u" > > > > where all PRIu* except PRIu64 are the same. > > > > Therefore, using PRIu8 or PRIx8 with the int return type of > > vlan_tci_to_pcp() is causing compiler warnings on macOS. > > What are the warnings? See https://travis-ci.org/openvswitch/ovs/jobs/197378752#L1303 There are plenty of other warnings due to similar situation (if they are not problems).
> > There is no real problem with using %hhd or %hhu to print an int, > because printf() cannot tell the difference between an int and a char: > they are both passed as int. You may be right about printf with regard to an int and a char. But how about an int specifier and a long variable? When I noticed the Wformat warning messages on macOS, I have no idea whether there is a hidden issue where the format specifier might be truncating a variable. The only way to be sure is to clean up the code base to remove the warning messages even if they are just noise. > > > As PRIu8 and PRIx8 are indeed accurate specifier for pcp (Priority code > > point), the patch proposes changing the return type of > > vlan_tci_to_pcp(). > > > > In addition, the patch includes changes of format specifiers to > > consistently use PRI* specifier. But unfortunately as you pointed out > > below, there are two "%d" occurrences I missed. I'll put these specifier > > changes into a separate commit for clarity. > > I don't see how putting them in a separate commit provides "clarity" > since the lack of the changes is most of my problem with the commit. _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
