On Mon, Mar 8, Bob Friesenhahn <bfriesen@xxxxxxxxxxxxxxxxxxx> wrote: > It is also interesting to note that it is usually ok for the > content of the header file to be parsed any number of times. > The only exception might be with some weird macro expansion > (but that would be a bug). > > The conditional inclusion of content is only an optimization. If you have a struct definition (C/C++) or a typedef (C) in the .h file, C compilers may refuse to process it twice and an inclusion guard is needed: user@host # cat x.h typedef int counter_t; user@host # cat x.c #include "x.h" #include "x.h" int main(void) { return 0; } user@host # gcc x.c In file included from x.c:2: x.h:1: redefinition of `counter_t' x.h:1: `counter_t' previously declared here user@host # tcc x.c x.h:1: Error: duplicate typedef 'counter_t' x.c: 0 warnings, 1 error, 0 serious errors oki, Steffen _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx http://lists.gnu.org/mailman/listinfo/autoconf