printf's "%zu" format expects an argument of type size_t. In the sample program, the corresponding argument is of type size_t in all the printf calls (the first because strspn() is defined to return a size_t result, and the second because of the explicit cast, and similarly for the others). For a call to strlen() or to a user-defined function func(), gcc rightly does not complain. For a call to strspn(), even with an explicit cast, gcc incorrectly complains that the arguments is of type ‘sizetype’ -- which, as far as I can tell, doesn't exist. (If I try to add a variable definition of type ‘sizetype’, I get "error: unknown type name ‘sizetype’", and I can find no reference to ‘sizetype’ in any of my system's headers.) I see nothing unusual in the declaration of strspn() in /usr/include/string.h. $ uname -a Linux kvetch 3.2.0-29-generic-pae #46-Ubuntu SMP Fri Jul 27 17:25:43 UTC 2012 i686 i686 i386 GNU/Linux $ cat /etc/lsb-release DISTRIB_ID=Ubuntu DISTRIB_RELEASE=12.10 DISTRIB_CODENAME=quantal DISTRIB_DESCRIPTION="Ubuntu quantal (development branch)" $ gcc --version gcc (Ubuntu/Linaro 4.7.0-7ubuntu3) 4.7.0 Copyright (C) 2012 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. $ cat c.c #include <string.h> #include <stdio.h> extern size_t func(void); int main(void) { printf("%zu\n", strspn("abc", "abcdefg")); /* line 7 */ printf("%zu\n", (size_t)strspn("abc", "abcdefg")); /* line 8 */ printf("%zu\n", strlen("foo")); printf("%zu\n", (size_t)strlen("foo")); printf("%zu\n", func()); printf("%zu\n", (size_t)func()); return 0; } $ gcc -c -std=c99 -pedantic c.c c.c: In function ‘main’: c.c:7:5: warning: format ‘%zu’ expects argument of type ‘size_t’, but argument 2 has type ‘sizetype’ [-Wformat] c.c:8:5: warning: format ‘%zu’ expects argument of type ‘size_t’, but argument 2 has type ‘sizetype’ [-Wformat] $
It is also needed to use -Wall. Both arguments to strspn () are constants, so in this case the __builtin_strspn () is used. You shouldn't see this warning with -fno-builtin-strspn. Thus <string.h> is correct in this regard. GCC 4.[1-5] are without warnings, with 4.6 I get: /home/marek/rh/tests/pr54486.c: In function ‘main’: /home/marek/rh/tests/pr54486.c:7:5: warning: format ‘%zu’ expects argument of type ‘size_t’, but argument 2 has type ‘long unsigned int’ [-Wformat] /home/marek/rh/tests/pr54486.c:8:5: warning: format ‘%zu’ expects argument of type ‘size_t’, but argument 2 has type ‘long unsigned int’ [-Wformat] with 4.7/trunk: /home/marek/rh/tests/pr54486.c: In function ‘main’: /home/marek/rh/tests/pr54486.c:7:5: warning: format ‘%zu’ expects argument of type ‘size_t’, but argument 2 has type ‘sizetype’ [-Wformat] /home/marek/rh/tests/pr54486.c:8:5: warning: format ‘%zu’ expects argument of type ‘size_t’, but argument 2 has type ‘sizetype’ [-Wformat
Confirmed. Here is a shorter testcase that explicitly uses the builtins: #include <stdio.h> int main(void) { __builtin_printf("%zu\n", __builtin_strspn("abc", "abcdefg")); /* line 7 */ __builtin_printf("%zu\n", (size_t)__builtin_strspn("abc", "abcdefg")); /* line 8 */ __builtin_printf("%zu\n", __builtin_strlen("abc")); /* line 9 */ return 0; }
Likely caused by http://gcc.gnu.org/viewcvs?view=revision&revision=163994 (too lazy to narrow it down from r163926 - r164000 range).
Author: jakub Date: Wed Sep 5 16:27:55 2012 New Revision: 190986 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=190986 Log: PR middle-end/54486 * builtins.c (fold_builtin_strspn, fold_builtin_strcspn): Use build_int_cst with size_type_node instead of size_int. * c-c++-common/pr54486.c: New test. Added: trunk/gcc/testsuite/c-c++-common/pr54486.c Modified: trunk/gcc/ChangeLog trunk/gcc/builtins.c trunk/gcc/testsuite/ChangeLog
Author: jakub Date: Wed Sep 5 16:29:42 2012 New Revision: 190987 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=190987 Log: PR middle-end/54486 * builtins.c (fold_builtin_strspn, fold_builtin_strcspn): Use build_int_cst with size_type_node instead of size_int. * c-c++-common/pr54486.c: New test. Added: branches/gcc-4_7-branch/gcc/testsuite/c-c++-common/pr54486.c Modified: branches/gcc-4_7-branch/gcc/ChangeLog branches/gcc-4_7-branch/gcc/builtins.c branches/gcc-4_7-branch/gcc/testsuite/ChangeLog
Author: jakub Date: Wed Apr 3 17:57:32 2013 New Revision: 197444 URL: http://gcc.gnu.org/viewcvs?rev=197444&root=gcc&view=rev Log: Backported from mainline 2012-09-05 Jakub Jelinek <jakub@redhat.com> PR middle-end/54486 * builtins.c (fold_builtin_strspn, fold_builtin_strcspn): Use build_int_cst with size_type_node instead of size_int. * c-c++-common/pr54486.c: New test. Added: branches/gcc-4_6-branch/gcc/testsuite/c-c++-common/pr54486.c Modified: branches/gcc-4_6-branch/gcc/ChangeLog branches/gcc-4_6-branch/gcc/builtins.c branches/gcc-4_6-branch/gcc/testsuite/ChangeLog