On 08/08/16 19:28, Ramsay Jones wrote: > > > On 08/08/16 17:30, Johannes Sixt wrote: >> Am 07.08.2016 um 22:34 schrieb Ramsay Jones: >>> On 05/08/16 23:26, Johannes Sixt wrote: > [snip] >>> At this point 'enum iterator_selection' is an incomplete type and may >>> be used when the size of the object is not required. It is not needed, >>> for example, when a typedef name is being declared as a pointer to, or >>> as a function returning such a type. However, such a type must be >>> complete before such a function is called or defined. >> >> All you say is true when it is a struct type, of course. But I doubt that there exists such a thing called "incomplete enumeration type" in C. In fact, with these keywords I found https://gcc.gnu.org/onlinedocs/gcc/Incomplete-Enums.html which indicates that this is a GCC extension. > > Ah, well spotted! > > You prompted me to look at the C99 (and C11) standards, in particular > sections 6.7.2.2 (Enumeration specifiers) and 6.7.2.3 (Tags). > > So, while (technically) enumeration types are incomplete prior to the > closing } in its definition, the constraint imposed in 6.7.2.3-2 states: > > "A type specifier of the form > enum identifier > without an enumerator list shall only appear after > the type it specifies is complete" > > which pretty much rules out its use here. BTW, you can make gcc be that 'pickier compiler' you mentioned, thus: $ rm refs.o $ make CFLAGS='-g -O2 -Wall -std=c99 -pedantic' refs.o * new build flags CC refs.o In file included from refs.c:8:0: refs/refs-internal.h:363:14: warning: ISO C forbids forward references to ‘enum’ types [-Wpedantic] typedef enum iterator_selection ref_iterator_select_fn( ^ $ :-D 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