https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67820
Bug ID: 67820
Summary: Move obscure warning about null pointers into prime
time
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: dcb314 at hotmail dot com
Target Milestone: ---
Consider this code
extern void g( char *);
void f( char * p)
{
if (p < 0)
g(p);
if (p <= 0)
g(p);
if (p >= 0)
g(p);
if (p > 0)
g(p);
}
Compiled by trunk gcc
$ ~/gcc/results/bin/gcc -c -O2 -Wall oct2a.cc
$
Wierdly, nothing said. Then compiled with more warnings
$ ~/gcc/results/bin/gcc -c -O2 -Wall -Wextra oct2a.cc
oct2a.cc: In function ‘void f(char*)’:
oct2a.cc:6:10: warning: ordered comparison of pointer with integer zero
[-Wextra]
if (p < 0)
^
oct2a.cc:8:11: warning: ordered comparison of pointer with integer zero
[-Wextra]
if (p <= 0)
^
oct2a.cc:11:11: warning: ordered comparison of pointer with integer zero
[-Wextra]
if (p >= 0)
^
oct2a.cc:13:10: warning: ordered comparison of pointer with integer zero
[-Wextra]
if (p > 0)
^
My experience is that most folks use -Wall, but only a very few
use -Wextra, because it produces a whole lot of other obscure warnings
on production code.
I checked the source code of redhat fedora and I estimate about
200 bugs would be detected by moving only this warning from -Wextra
into -Wall.
