Re: [[GCC13][Patch][V3] 1/2] Add a new option -fstrict-flex-array[=n] and new attribute strict_flex_array

[Qing Zhao <qing.zhao@oracle.com>]

> On Aug 31, 2022, at 4:16 PM, Qing Zhao via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> 
> Okay, I am fine with this.

Another thought on this is:

One of the major purposes of the new option -fstrict-flex-array is to encourage standard conforming programming style. 

So, it might be reasonable to treat -fstrict-flex-array similar as -pedantic (but only for flexible array members)? 
If so, then issuing warnings when the standard doesn’t support is reasonable and desirable. 

(I guess that this is the original motivation to add such warnings).

Qing
> 
> Richard and Kees,  what’s your opinion on this?
> 
> thanks.
> 
> Qing
> 
>> On Aug 31, 2022, at 4:09 PM, Joseph Myers <joseph@codesourcery.com> wrote:
>> 
>> On Wed, 31 Aug 2022, Qing Zhao wrote:
>> 
>>>>> When -std=gnu89 + -fstrict-flex-array=3 (ONLY C99 flexible array member 
>>>>> [] is treated as a valid flexible array) present together,
>>>> 
>>>> That seems reasonable enough without a warning.  If people want a warning 
>>>> for flexible array members in older language modes, they can use 
>>>> -pedantic; I don't think we need to warn for any particular 
>>>> -fstrict-flex-array modes there.
>>> 
>>> So, you mean,
>>> 
>>> 1. GCC with -std=gnu89 support all [0], [1], and [] as Flexible array member;
>>> 2. Therefore. -std=gnu89 + -fstrict-flex-array=3 does not need a warning;
>>> 
>>> ?
>> 
>> Yes.
>> 
>>> Then, how about:
>>> 
>>> -std=c89:
>>> 
>>> 1. GCC with -std=c89 also support all [0], [1], and [] as Flexible array member;
>>> 2, therefore, -std=c89 + -fstrict-flex-array does not need a warning too.
>>> 
>>> ?
>> 
>> Yes.
>> 
>> -- 
>> Joseph S. Myers
>> joseph@codesourcery.com
>