Bug 2333039

I'm experimentally rebuilding rawhide with the not-yet-released GCC 15 to see if anything breaks, and to help write the porting guide.  See https://fedoraproject.org/wiki/User:Dmalcolm/gcc-15

In https://download.copr.fedorainfracloud.org/results/dmalcolm/gcc-15-smoketest-3/fedora-rawhide-x86_64/08410915-389-ds-base/builder-live.log.gz

I see this failure:

ldap/servers/slapd/compare.c: In function 'do_compare':
ldap/servers/slapd/compare.c:184:19: error: too many arguments to function 'be->be_database->plg_un.plg_un_db.plg_un_db_compare'
  184 |             rc = (*be->be_compare)(pb);
      |                  ~^~~~~~~~~~~~~~~~
make[1]: *** [Makefile:10278: ldap/servers/slapd/ns_slapd-compare.o] Error 1

whereas the build succeeded with gcc 14.

Looking at the source I see:

slap.h:1467:#define be_compare be_database->plg_compare
    struct slapdplugin *be_database; /* single plugin */
#define plg_compare plg_un.plg_un_db.plg_un_db_compare

slap.h:1074:            IFP plg_un_db_compare;              /* compare */

where slapi-private.h has:

/* JCMREPL - IFP and CFP should be defined centrally */
#ifndef _IFP
#define _IFP
typedef int (*IFP)(); /* takes undefined arguments */
#endif

This is probably due to GCC 15 defaulting to -std=gnu23, whereas GCC 14 defaulted to -std=gnu17, and C23 is stricter about function prototypes than C17.


Reproducible: Always