Jonathan Nieder wrote: > Ramsay Jones wrote: > >> In particular, some versions of gcc complains as follows: >> >> CC vcs-svn/sliding_window.o >> vcs-svn/sliding_window.c: In function `check_overflow': >> vcs-svn/sliding_window.c:36: warning: comparison is always false \ >> due to limited range of data type > > Yuck. Suppressing this warning would presumably also suppress the > optimization that notices the comparison is always false. I didn't check, but I would assume so. I would prefer not to loose any chance at optimizing the code, but in this case, given that we are talking about a fatal error path, I don't think it is much of a loss. > The -Wtype-limits warning also triggers in some other perfectly > reasonable situations: see <http://gcc.gnu.org/PR51712>. [...] >> Note that the "some versions of gcc" which complain includes 3.4.4 and >> 4.1.2, whereas gcc version 4.4.0 compiles the code without complaint. > > Thanks for tracking this down. Interesting. -Wtype-limits was split > out from the default set of warnings (!) in gcc 4.3 to address > <http://gcc.gnu.org/PR12963>, among other bugs (r124875, 2007-05-20). Thanks for the above references, and for taking the time to track them down. > Is there some less ugly way to write the condition "if this value is > not representable in this type"? > > I guess I could live with something like the following (please don't > take the names too seriously): > > static inline off_t off_t_or_die(uintmax_t val, const char *msg_if_bad) > { > if (val > maximum_signed_value_of_type(off_t)) > die("%s", msg_if_bad); > return (off_t) val; > } > > ... > > off_t delta_len = off_t_or_die(len, "enormous delta"); > postimage_len = apply_delta(delta_len, input, ...); > > What do you think? An static inline function was actually my first thought (although I had something more like Junio's suggestion [elsewhere in this thread] in mind), but I didn't want to place it in git-compat-util.h and could not find a suitable place in the vcs-svn directory. Hmm, I will send a v2 patch along these lines ... ATB, Ramsay Jones -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html