Re: [PATCH] treewide: Replace zero-length arrays with flexible-array member

[Gustavo A. R. Silva]

On 2/11/20 13:35, Kees Cook wrote:
> On Tue, Feb 11, 2020 at 11:41:26AM -0600, Gustavo A. R. Silva wrote:
>> The current codebase makes use of the zero-length array language
>> extension to the C90 standard, but the preferred mechanism to declare
>> variable-length types such as these ones is a flexible array member[1][2],
>> introduced in C99:
>>
>> struct foo {
>>         int stuff;
>>         struct boo array[];
>> };
>>
>> By making use of the mechanism above, we will get a compiler warning
>> in case the flexible array does not occur last in the structure, which
>> will help us prevent some kind of undefined behavior bugs from being
>> unadvertenly introduced[3] to the codebase from now on.
> 
> Is there a compiler warning we can enable to avoid new 0-byte arrays
> from entering the kernel source tree? I can only find "-pedantic" which
> enables way too many other checks.
> 

Months ago, I only found -pedantic, too. And we definitely don't want
to use it for this. :/

--
Gustavo