Re: [RFC PATCH bpf-next] bpftool: Mark generated skeleton headers as system headers

[Quentin Monnet <quentin@isovalent.com>]

On 28/07/2022 19:25, Yonghong Song wrote:
> 
> 
> On 7/28/22 9:56 AM, Jörn-Thorben Hinz wrote:
>> Hi,
>>
>> after compiling a skeleton-using program with -pedantic once and
>> stumbling across a tiniest incorrectness in skeletons with it[1], I was
>> debating whether it makes sense to suppress warnings from skeleton
>> headers.
>>
>> Happy about comments about this. This change might be too suppressive
>> towards warnings and maybe ignoring only -Woverlength-strings directly
>> in OBJ_NAME__elf_bytes() be a better idea. Or keep all warnings from
>> skeletons available as-is to have them more visible in and around
>> bpftool’s development.
> 
> This is my 2cents. As you mentioned, skeleton file are per program
> and not in system header file directory. I would like not to mark
> these header files as system files. Since different program will
> generate different skeleton headers, suppressing warnings
> will prevent from catching potential issues in certain cases.
> 
> Also, since the warning is triggered by extra user flags like -pedantic
> when building bpftool, user can also add -Wno-overlength-strings
> in the extra user flags.

I agree with Yonghong, I don't think it's a good idea to mark the whole
file as a system header. I would maybe consider the other solution where
we can disable the warning locally in the skeleton, just around
OBJ_NAME__elf_bytes() as you suggested. Although I suppose we'd need
several pragmas if we want to silence it for GCC and clang, for example?
It looks like your patch was only addressing GCC?

Thanks for the contribution,
Quentin