http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54486
Bug #: 54486
Summary: Spurious printf format warning mentions nonexistent
type 'sizetype'
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: keith.s.thomp...@gmail.com
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]
$
