Re: [PATCH 1/1] eal: add C++ include guard in generic/rte_vect.h

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 2/2/2024 9:40 AM, Bruce Richardson wrote:
> On Fri, Feb 02, 2024 at 10:18:23AM +0100, Thomas Monjalon wrote:
>> 02/02/2024 06:13, Ashish Sadanandan:
>>> The header was missing the extern "C" directive which causes name
>>> mangling of functions by C++ compilers, leading to linker errors
>>> complaining of undefined references to these functions.
>>>
>>> Fixes: 86c743cf9140 ("eal: define generic vector types")
>>> Cc: nelio.laranjeiro@6wind.com
>>> Cc: stable@dpdk.org
>>>
>>> Signed-off-by: Ashish Sadanandan <ashish.sadanandan@gmail.com>
>>
>> Thank you for improving C++ compatibility.
>>
>> I'm not sure what is best to fix it.
>> You are adding extern "C" in a file which is not directly included
>> by the user app. The same was done for rte_rwlock.h.
>> The other way is to make sure this include is in an extern "C" block
>> in lib/eal/*/include/rte_vect.h (instead of being before the block).
>>
>> I would like we use the same approach for all files.
>> Opinions?
>>
> I think just having the extern "C" guard in all files is the safest choice,
> because it's immediately obvious in each and every file that it is correct.
> Taking the other option, to check any indirect include file you need to go
> finding what other files include it and check there that a) they have
> include guards and b) the include for the indirect header is contained
> within it.
> 

I assume you mean all header files exposed to user (ones installed by
meson), in that case +1

> Adopting the policy of putting the guard in each and every header is also a
> lot easier to do basic automated sanity checks on. If the file ends in .h,
> we just use grep to quickly verify it's not missing the guards. [Naturally,
> we can do more complete checks than that if we want, but 99% percent of
> misses can be picked up by a grep for the 'extern "C"' bit]
> 
> /Bruce