Re: [PATCH] Add __BEGIN_DECLS and __END_DECLS for C++

[Zack Weinberg <zackw at panix dot com>]

On Thu, May 11, 2017 at 11:10 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Thu, May 11, 2017 at 7:57 AM, Zack Weinberg <zackw@panix.com> wrote:
>> On Thu, May 11, 2017 at 10:45 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>> On Thu, May 11, 2017 at 7:43 AM, Zack Weinberg <zackw@panix.com> wrote:
>>>>
>>>> This program does not appear to need ifunc-impl-list.h.  Please elaborate.
>>>
>>> Please see hjl/x86/optimize branch in glibc git repo.
>>
>> I don't especially appreciate being made to dig through a bunch of
>> code I'm unfamiliar with.  It would have been easy for you to write
>> "The existing benchtests framework uses ifunc-impl-list.h to iterate
>> over all ifunc implementations of a particular string function.  This
>> works as long as the test program is C, but I want to integrate a
>> third-party benchmark <url> written in C++, so I need to make
>> ifunc-impl-list.h C++-safe".  If that had accompanied the original
>> patch it would have been better all around.
>>
>> It looks to me as if IFUNC_IMPL_ADD is not C++-safe and cannot easily
>
> IFUNC_IMPL_ADD is only used in ifunc-impl-list.c, which is the
> part of libc and in C.

Can IFUNC_IMPL_ADD be removed from ifunc-impl-list.h then?  I would be
okay with adding __BEGIN_DECLS/__END_DECLS to the header as long as
all of the code within it -- including macros -- was safe for use from
C++ programs, and with a comment explaining that the header may get
used from C++ benchmarks.

>> be made so, so I don't like this change.  What prevents you from
>> rewriting the third-party benchmark in C, since you have to modify it
>> anyway?  It's not doing anything that is difficult in plain C.
>
> I'd to preserve the original benchmark as much as possible so that
> little is lost, comparing with the original one.

That's fair.

zw