On Tue, 31 Aug 2021 at 09:11, Utkarsh Singh wrote:
>
> Hello GCC mailing list,
>
> In one of my friend's C programming class, they asked him a question on
> the topic of array bounds based on the follwing code snippet:
>
> #include <stdio.h>
>
> int main(void)
> {
> char str[] = {'G' , 'C' , 'C' };
> str[3] = '\0' ; /* Isn't this invalid? */
> printf("%s\n", str);
> }
>
> In an ideal case, str[3] should be a case of out-of-bound array access.
> But when compiling the above with -Wall option flag GCC shows no
> warning. So, am I missing something?
This question belongs on the gcc-help mailing list, not here.
The code has undefined behaviour.
Some GCC warnings depend on checks done during optimization. GCC will
warn about this code if you use -Wall -O2 and you will get a runtime
error if you compile with -fsanitize=undefined
