[cfe-dev] Clang: QT header compilation error

[Richard Smith]

On Mon, Nov 19, 2012 at 11:05 AM, Stephen Kelly <steveire at gmail.com> wrote:
> Matthieu Monrocq wrote:
>
>> On Mon, Nov 19, 2012 at 2:08 PM, Dmitri Gribenko
>> <gribozavr at gmail.com>wrote:
>>
>>> On Mon, Nov 19, 2012 at 3:02 PM, Sujit Kamthe
>>> <Sujit.Kamthe at kpitcummins.com> wrote:
>>> >
>>> > Hi,
>>> >
>>> > While I was running clang on a QT code, It flagged a compilation error
>>> > in a standard QT header file.
>>> >
>>> > include\QtCore/qvector.h:565:12: error: missing 'typename'
>>> >
>>> >       prior to dependent type name 'QVector<T>::iterator'
>>> >
>>> > Q_TYPENAME QVector<T>::iterator QVector<T>::insert(iterator before,...
>>> >
>>> >            ^~~~~~~~~~~~~~~~~~~~
>>> >
>>> > include\QtCore/qvector.h:599:12: error: missing 'typename'
>>> >
>>> >       prior to dependent type name 'QVector<T>::iterator'
>>> >
>>> > Q_TYPENAME QVector<T>::iterator QVector<T>::erase(iterator abegin,...
>>> >
>>> >            ^~~~~~~~~~~~~~~~~~~~
>>> >
>>> >
>>> >
>>> > Attaching the header file along.
>>>
>>> Hi Sujit,
>>>
>>> Unfortunately, the header file alone is not helpful.  It is not
>>> obvious what Q_TYPENAME expands to.  Could you please provide a
>>> preprocessed file?  (Just replace -c with -E on the compilation
>>> command line that is failing.)
>>>
>>> Dmitri
>>>
>>> --
>>> main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if
>>> (j){printf("%d\n",i);}}} /*Dmitri Gribenko
>>> <gribozavr at gmail.com>*/
>>> _______________________________________________ cfe-dev mailing list
>>> cfe-dev at cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>>>
>>
>> At a glance (given the diagnostic and the macro) I suppose that Q_TYPENAME
>> should have expanded into typename (which would have made the code
>> correct) and did not.
>>
>> As such, the preprocessed source will only be of moderate usefulness
>> (confirming the diagnosis) and we will also need the definition of this
>> Q_TYPENAME macro. It's probably defined differently depending on the
>> platform and mistake clang for a non-compliant compiler.
>>
>> -- Matthieu
>
> I tried to reproduce this in my Qt 4 build, but I could not reproduce it:
>
> stephen at hal:~/dev/prefix/qt48/include$ clang++ -I. -E QtCore/qvector.h  >
> out
> clang-3: warning: treating 'c-header' input as 'c++-header' when in C++
> mode, this behavior is deprecated
> stephen at hal:~/dev/prefix/qt48/include$ l
> out  Qt3Support/  QtDBus/         QtDesigner/  QtHelp/        QtNetwork/
> QtScript/       QtSql/  QtTest/     QtWebKit/  QtXmlPatterns/
> Qt/  QtCore/      QtDeclarative/  QtGui/       QtMultimedia/  QtOpenGL/
> QtScriptTools/  QtSvg/  QtUiTools/  QtXml/
>
>
> From my reading qglobal.h, Q_TYPENAME should be 'typename' everywhere except
> some ancient DEC C++ and ancient xlC compilers.

Right. The macro has even been removed in Qt trunk (and replaced by
direct uses of 'typename'). It seems very unlikely this is a problem
in Clang.