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

[Siddhesh Poyarekar <siddhesh@gotplt.org>]

On 2022-12-01 18:19, Kees Cook wrote:
> 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.

That's how I understood Richard's comment.

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

I suppose it would be independent of -Wall, dependent completely on 
-fstrict-flex-arrays.

Thanks,
Sid