See example below: I'm getting warnings emitted by the -flto link stage.
I'd like to selectively disable these warnings in my build scripts, but the
usual -Wno-* option doesn't seem to have any effect. Is it supposed to
work? Is there another way to do it?
Thanks,
Jay.
$ gcc --version
gcc (Ubuntu 7.2.0-8ubuntu3) 7.2.0
Copyright (C) 2017 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 a.c
#include <string.h>
void a(char * x, int n) {
memset(x, 0, n);
}
$ cat b.c
void a(char *, int);
int main() {
char x[3];
a(x, 4);
}
$ gcc -O3 -flto -c a.c b.c -Wno-stringop-overflow
$ gcc -O3 -flto a.o b.o -Wno-stringop-overflow
In function ‘memset’,
inlined from ‘main’ at a.c:3:2:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:71:10: warning:
‘__builtin___memset_chk’ writing 4 bytes into a region of size 3 overflows
the destination [-Wstringop-overflow=]
return __builtin___memset_chk (__dest, __ch, __len, __bos0 (__dest));
^
