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

[Alejandro Colomar <alx.manpages@gmail.com>]

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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
>      buf.c:8:17: warning: format specifies type 'void *' but the argument has 
> type 'char *' [-Wformat-pedantic]
>          printf("%p\n", p);
>                  ~~     ^
>                  %s
>      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]
>          p = buf + 6;
>              ^     ~
>      buf.c:5:2: note: array 'buf' declared here
>          char *p, buf[5];
>          ^
>      2 warnings generated.
> 
> Cheers,
> 
> Alex
> 
> 

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

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