[Development] check, Mate!

[Gábor Lehel]

2012/1/9 Stephen Kelly <stephen.kelly at kdab.com>:
> On Monday, January 09, 2012 18:00:29 Gábor Lehel wrote:
>
>> 2012/1/9 Gábor Lehel <illissius at gmail.com>:
>
>> > Perhaps we could use GCC's poison pragma[1] to make sure that no one
>
>> > uses them? In some cases it would just be replacing one error message
>
>> > with another (though perhaps a more user-friendly one), but in other
>
>> > cases it would substitute an error for no error. Of course, it only
>
>> > works with GCC. (TBF I haven't checked any other compilers.)
>
>> >
>
>> > [1] http://gcc.gnu.org/onlinedocs/cpp/Pragmas.html
>
>>
>
>> ...though that would also poison them for user code which I'm not sure
>
>> we want, so I suppose you would only want to turn it on when building
>
>> Qt itself.
>
>
>
> I think this is a good idea. It doesn't matter that it only works with GCC.
> If any platform fails, the CI gate does not open for the patch.
>
>
>
> There's a few more instances of 'check' in Qt, after clearing those up, I
> could write a patch to add the pragma to qglobal which user code could
> enable if desired (just like QT_STRICT_ITERATORS or QT_NO_KEYWORDS for
> example).
>
>
>
> #ifdef QT_CHECK_MACRO_CONFLICTS
>
> #pragma GCC poison check <others...>
>
> #endif
>
>
>
> Any suggestions for an alternative name to QT_CHECK_MACRO_CONFLICTS ? Simply
> 'check' perhaps :) ?

...one complication is that this will also result in an error when
using the macros _for their intended purpose_. So for the ones which
we legitimately want to use (if any) we might want to only poison them
only on the platforms which _don't_ define them, which would
effectively force them to be ifdeffed to the platforms which do.

Also, when poisoning an already-defined macro GCC says:

a.cpp:3: warning: poisoning existing macro "foo"

I don't know if there's any way to turn it off (doesn't seem to be) or
if it's a problem.

If it's a problem (and maybe regardless) I guess you'd have to do it like:

#ifdef QT_POISON_NONPORTABLE_IDENTIFIERS
#    ifndef check
#        pragma GCC poison check
#    endif
#    ifndef major
#        pragma GCC poison major
#    endif
#    ... etc. ...
#endif


>
>
>
> Thanks,
>
>
>
> --
>
> Stephen Kelly <stephen.kelly at kdab.com> | Software Engineer
>
> KDAB (Deutschland) GmbH & Co.KG, a KDAB Group Company
>
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>
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>
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