On Sat, Oct 24, 2015 at 02:41:59PM -0400, Ganesh Ajjanagadde wrote: > On Sat, Oct 24, 2015 at 2:33 PM, Michael Niedermayer > <mich...@niedermayer.cc> wrote: > > On Sat, Oct 24, 2015 at 09:29:23AM -0400, Ganesh Ajjanagadde wrote: > >> ISO C restricts enumerator values to the range of int. Thus (for instance) > >> 0x80000000 > >> unfortunately does not work, and throws a warning with -Wpedantic on > >> clang 3.7. > >> > >> This fixes such errors by explicitly casting as an int, doing the > >> desired unsigned to signed conversion. This method works on all current > >> architectures. Tested with FATE. > >> > >> Signed-off-by: Ganesh Ajjanagadde <gajjanaga...@gmail.com> > > > > Simply changing the values to signed is not correct / not sufficient > > the code assumes that they are unsigned > > enums are ints (and hence signed).
this is not true (though thats off topic but you seemed interrested in the C spec) 6.7.2.2 Enumeration specifiers ... 4 Each enumerated type shall be compatible with char, a signed integer type, or an unsigned integer type. The choice of type is implementation-defined,110) but shall be capable of representing the values of all the members of the enumeration. The enumerated type is incomplete until after the } that terminates the list of enumerator declarations. so a enum type can be almost anything the implementation likes it to be. 2 enums dont even need to be using the same type and this is not just specification talk, gcc does this actually, for example it will use (u)int64 as type when things dont fit in an (unsigned) int also on at least some embeded platforms gcc will use shorts for enums that fit in a short int (no i dont know which exactly but i read about people stumbling into this so it must happen on some platform) > I doubt code assumed that they are > unsigned. If code depended on these being unsigned constants, then > there is no way of placing them in an enum. Are you fine with a macro, > or do you prefer a static const style? Generally, it seems like FFmpeg > prefers the macro method for defining such constants/flags. if have no preferrance for anything beyond the code working [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Many that live deserve death. And some that die deserve life. Can you give it to them? Then do not be too eager to deal out death in judgement. For even the very wise cannot see all ends. -- Gandalf
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