[Interest] QT_LARGEFILE_SUPPORT : macro redefinition.

[william.crocker at analog.com]

On 06/09/2014 04:18 AM, Konrad Rosenbaum wrote:
> Hi,
>
> On Sunday 08 June 2014 19:28:34 Bill Crocker wrote:
>> I am upgrading a project from Qt 4.7.1 to Qt 4.8.6
>> When I build this project on Windows, I now see this:
>>
>>       c:\qt\4.8.6\include\qtcore\../../src/corelib/global/qconfig.h(46) :
>>           warning C4005: 'QT_LARGEFILE_SUPPORT' : macro redefinition
>>           command-line arguments :  see previous definition of
>> 'QT_LARGEFILE_SUPPORT'
>>
>> I am building in VisualStudio 2008 C++
>> from an import of my .pro file.
>>
>> Does anyone know what might be causing this?
>
> As the friendly warning is telling you: QT_LARGEFILE_SUPPORT is defined both
> in qconfig.h and on the commandline given to your compiler.... ;-)
>
> Short answer: ignore this one, it is harmless.
>
> Long answer:
>
> qconfig.h contains platform configurations for Qt, most command line
> parameters come from the mkspec of your platform. Both describe how your
> platform behaves in regards to Qt. For some odd reason this define appears
> in both without a guard.
>
> As said above: it is harmless. Your compiler is just a bit picky about
> preprocessor symbols.
>
> If you absolutely and positively cannot live with this warning:
>
> A quickfix would be to include this _before_any_Qt_includes_(!!) in the cpp-
> file that has this problem:
>
> #ifdef QT_LARGEFILE_SUPPORT
> #undef QT_LARGEFILE_SUPPORT
> #endif
>
> A more robust fix would be to put this into the beginning of qconfig.h.
>
> It's important that this #define happens at least once, otherwise you'll
> have trouble handling big files.
>

Thanks.
I was just surprised to see this.
It leads me to believe that something is not installed correctly.
Why would this appear in an X.8.6 (mature?) release.

Bill