https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116672
Bug ID: 116672
Summary: gcc-11 and higher versions failed to check the
strict-aliasing rule.
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: zzy439...@alibaba-inc.com
Target Milestone: ---
The error occurs when I run the following code with GCC 11 and higher versions,
and turn on -O2 flag.
---test.c---
#include <ctype.h>
#include <stdio.h>
static void func (const unsigned char **pstr)
{
while (isdigit(*++(*pstr)))
continue;
}
int main() {
const char *f = "1a";
func ((const unsigned char **) &f);
printf("%s\n", f);
return 0;
}
---
The command is:
$gcc-11 -O2 test.c -o test
It should outputs "a", but actually it outputs "1a". While I know the code is
not comply to the strict-aliasing rule that opened by default with -O2
optimization, but the error only occurs in GCC 11 and higher versions. It seems
that lower versions would check if the code is comply to the strict-aliasing
rule, while the higher versions will not.
