Re: [BUG] missing warning for pointer arithmetic out of bounds

[Alejandro Colomar via Gcc]

On 12/13/22 20:08, Alejandro Colomar wrote:

Hi!

For the following program:


     $ cat buf.c
     #include <stdio.h>

     int main(void)
     {
         char *p, buf[5];

         p = buf + 6;
         printf("%p\n", p);
     }


There are no warnings in gcc, as I would expect:

I just re-read my text, and it is ambiguous.  I meant that I expect warnings.

     $ gcc -Wall -Wextra buf.c -O0

Clang does warn, however:

     $ clang -Weverything -Wall -Wextra buf.c -O0

         printf("%p\n", p);
                 ~~     ^
                 %s

         p = buf + 6;
             ^     ~
     buf.c:5:2: note: array 'buf' declared here
         char *p, buf[5];
         ^
     2 warnings generated.

Cheers,

Alex

    buf.c:8:17: warning: format specifies type 'void *' but the argument has type 'char *' [-Wformat-pedantic]     buf.c:7:6: warning: the pointer incremented by 6 refers past the end of the array (that contains 5 elements) [-Warray-bounds-pointer-arithmetic]

--
<http://www.alejandro-colomar.es/>

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