Re: [Qemu-devel] [RFC PATCH v3 02/11] Fix errors and warnings while compiling with c++ compilier

[Tomoki Sekiyama]

On 5/24/13 4:52 , "Stefan Hajnoczi" <address@hidden> wrote:

>On Thu, May 23, 2013 at 06:34:43PM +0000, Tomoki Sekiyama wrote:
>> On 5/23/13 8:12 , "Stefan Hajnoczi" <address@hidden> wrote:
>> 
>> >On Tue, May 21, 2013 at 11:33:41AM -0400, Tomoki Sekiyama wrote:
>> >> Add C++ keywords to avoid errors in compiling with c++ compiler.
>> >> This also renames class member of PciDeviceInfo to q_class.
>> >> 
>> >> Signed-off-by: Tomoki Sekiyama <address@hidden>
>> >> ---
>> >>  hmp.c           |    2 +-
>> >>  hw/pci/pci.c    |    2 +-
>> >>  scripts/qapi.py |    9 ++++++++-
>> >>  3 files changed, 10 insertions(+), 3 deletions(-)
>> >
>> >Please also extend scripts/checkpatch.pl.  Otherwise it is very likely
>> >that C++ keywords will be introduced again in the future.  Most people
>> >will not build the VSS code and therefore checkpatch.pl needs to ensure
>> >that patches with C++ keywords will not be accepted.
>> >
>> >Stefan
>> 
>> I think it would be difficult to identify problematic C++ keywords usage
>> from patches because headers can legally contain C++ keywords and
>> checkpatch.pl doesn't know where it should be used.
>> Do you have any good ideas?
>
>We can ignore false warnings for 0.1% of patches (the ones that touch
>VSS C++ code).  But for the remaining 99.9% of patches it's worth
>guarding against VSS bitrot.
>
>Remember not many people will compile it and therefore they won't notice
>when they break it.  I really think it's worth putting some effort in
>now so VSS doesn't periodically break.
>
>checkpatch.pl is a hacky sort of C parser.  It already checks for a
>bunch of similar things and it knows about comments, macros, and
>strings.  It does not perform #include expansion, so there is no risk of
>including system headers that have C++ code.
>
>Stefan

Thanks for your comment.

I'm still wondering because it actually causes a lot false positives
(not just 0.1%...) even for the patches not touching VSS.

For example, keyword 'class' is used in qdev-monitor.c, qom/object.c,
and a lot of files in hw/*/*.c and include/{hw,qom}/*.h, but
they have nothing to do with qemu-ga. Qemu-ga is just a part of whole
qemu source code, so I don't want to warn around the other parts.

Thanks,
Tomoki Sekiyama