On Wednesday, June 22, 2005, at 11:10PM, Ralf Wildenhues <Ralf.Wildenhues@xxxxxx> wrote: >Hi, > >* gnoop@xxxxxxx wrote on Wed, Jun 22, 2005 at 10:17:02PM CEST: >> I have a basic question that I couldn't find in the info docs or the >> goat book. What's the right way to deal with a prototype for a system >> library function that differs between platforms? I know how to check >> for headers and libraries, but don't know what the autotools way is to >> get around different prototypes. >> >> For example, on linux the scandir prototype is: >> >> int scandir(const char *dir, struct dirent ***namelist, >> int(*select)(const struct dirent *), >> int(*compar)(const struct dirent **, const struct dirent **)); >> >> and on darwin it's: >> >> int >> scandir(const char *dirname, struct dirent ***namelist, >> int (*select)(struct dirent *), >> int (*compar)(const void *, const void *)); >> >> I.e. the const is missing from darwin's 3rd parameter. > >Can't you just ignore this difference in your program? If you pass a >select function which eats a const argument, you are within ANSI C >bounds in either case. Ignore the warning some compiler may emit -- >it should rather be fixed. At least some C++ compilers fail. g++ fails with an err. gcc just issues a warning. > >If you ever encounter significant function definition differences, you >may look at the chapter > info Autoconf 'Library Functions' >of the manual and the corresponding implementations in >autoconf/function.m4 to search for a macro similar to your needs which >you can adjust. Be sure to use published macros only within your macro. > Thanks, Ralf. I finally found after following your reference that the info section that has examples for my problem is the 'Types' node (duh!). And there and looking at actypes.m4 I found that AC_TYPE_SIGNAL is a nice simple example of checking for and defining a data type. In the meantime, a solution I came up with was to define a macro using the AC_PROTOTYPE macro in the autoconf macro archive, which defines SCANDIR_ARG3 with the appropriate type. (Note, C++ is required to raise the compilation error.) AC_DEFUN([AC_PROTOTYPE_SCANDIR],[ AC_LANG_PUSH(C++) AC_PROTOTYPE(scandir, [ #include <dirent.h> ], [ const char * dir = 0; struct dirent ***namelist = 0; int(*select)(ARG3) = 0; scandir(dir, namelist, select, alphasort); ], ARG3, [const struct dirent *, struct dirent *]) AC_LANG_POP(C++) ]) _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx http://lists.gnu.org/mailman/listinfo/autoconf
