[Bug c++/57039] New: -Wsequence-point missing warning for such case

[tango_antispams at outlook dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57039



             Bug #: 57039

           Summary: -Wsequence-point missing warning for such case

    Classification: Unclassified

           Product: gcc

           Version: unknown

            Status: UNCONFIRMED

          Severity: normal

          Priority: P3

         Component: c++

        AssignedTo: unassig...@gcc.gnu.org

        ReportedBy: tango_antisp...@outlook.com





Hi,

I think -Wsequence-point should warn for such case:

#include <stdio.h>

int main(int argc, char* argv[])

{

    int color = argc;

    ++color = (color > 3) ? 0 : color;

    printf("argc = %d, color = %d\n", argc, color);

    return 0;

}



With -Wall, no warning at all.

Since the ++ operation and = operation can make real 'color' update in any

order.

(Use "2" or "2 3" or "2 3 4" as parameters and you can see difference:

> ./test

argc = 1, color = 2

> ./test 2

argc = 2, color = 3

> ./test 2 3

argc = 3, color = 0

> ./test 2 3 4

argc = 4, color = 0

)



What is your idea?



Thanks,

Tango





I am testing with such version:

Using built-in specs.

COLLECT_GCC=/pkg/software/gnu/gcc/4.7.2/bin/gcc

COLLECT_LTO_WRAPPER=/afs/amd64_linux24/usr/local/packages/software/gnu/gcc/4.7.2/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.7.2/lto-wrapper

Target: x86_64-unknown-linux-gnu

Configured with: ./configure --prefix=/pkg/software/gnu/gcc/4.7.2

Thread model: posix

gcc version 4.7.2 (GCC)