Re: [V2][PATCH 1/1] Add a new warning option -Wstrict-flex-arrays.

[Kees Cook <keescook@chromium.org>]

On Thu, Dec 01, 2022 at 10:27:41PM +0000, Qing Zhao wrote:
> Hi, Sid,
> 
> Thanks a lot for the input.
> 
> After more thinking based on your and Kees’ comments, I have the following thought:
> 
> 1. -fstrict-flex-arrays=level should control both GCC code gen and warnings consistently;
> 2. We need warnings specifically for -fstrict-flex-arrays=level to report any misuse of flexible 
>      array corresponding to the “level” to gradually encourage language standard.
> 
> So, based on the above two, I think what I did in this current patch is correct:
> 
> 1.  We eliminate the control from -Warray-bounds=level on treating flex arrays, 
>      now only "-fstrict-flex-arrasy=level" controls how the warning treating the flex arrays.
> 2.  We add a separate new warning -Wstrict-flex-arrays to report any misuse corresponding to
>      the different level of -fstrict-flex-arrays.
> 
> Although we can certainly merge these new warnings into -Warray-bounds, however, as Sid mentioned,
> -Warray-bounds does issue a lot more warnings than just flexible arrays misuse. I think it’s necessary 
> To provide a seperate warning to only issue flexible array misuse.
> 
> Let me know if you have any more comments on this.

Okay, that seems good. Given that -Warray-bounds is part of -Wall, what
should happen for -Wstrict-flex-arrays=N?

-- 
Kees Cook