qHash(double) problem with Qt 4.6 (tp1)

[sascha]

Hi, I compiled the beta now with MinGW (gcc 4.4) and using a QList<double> inside a Qt project without qwt is no problem.

Somehow the compiler gets confused at qwt_valuelist.h:48, where a QList<double> is explicitly instantiated for exporting it in the qwt.dll . Uncommenting this line, results in a successful build of qwt with gcc 4.4 and Qt 4.6 beta1.

Any ideas whats happening there?

Sascha

[Uwe]

Can you compile Qwt 5.2 with Qt 4.5.x and MinGW (gcc 4.4) or is it a problem of the compiler version ?

Uwe

[sascha]

I did that on Linux, cross-compiling with MinGW (gcc 4.4) for Windows and it worked, but I will try it on Windows natively in the next days.

Sascha

[Kazakus]

Had anybody managed with this? I've looked at qhash.h, and it's rewritten since qt 4.5, and I didn't managed to modify qwt so that it compiles for me

[Indalo]

Follow to qwt_valuelist.h and change this:

#if QT_VERSION < 0x040300
// Some compilers have problems, 
// without a qHash(double) implementation
#include <qset.h>
#include <qvector.h>
inline uint qHash(double key) { return uint(key); }
#endif

#if QT_VERSION < 0x040300
// Some compilers have problems, 
// without a qHash(double) implementation
#include <qset.h>
#include <qvector.h>
inline uint qHash(double key) { return uint(key); }
#endif

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to:

#if QT_VERSION == 0x040600
// Some compilers have problems, 
// without a qHash(double) implementation
#include <qset.h>
#include <qvector.h>
inline uint qHash(double key) { return uint(key); }
#endif

#if QT_VERSION == 0x040600
// Some compilers have problems, 
// without a qHash(double) implementation
#include <qset.h>
#include <qvector.h>
inline uint qHash(double key) { return uint(key); }
#endif

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[sascha]

Hi,

the hint posted by Indalo does not work for me.

I am using Qt 4.6 RC now and qwt still doesn't compile without modification. However, changing qwt_valuelist.h:37 from

#if defined(QWT_TEMPLATEDLL)

#if defined(QWT_TEMPLATEDLL)

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to

#if defined(QWT_TEMPLATEDLL) && QT_VERSION < 0x040600

#if defined(QWT_TEMPLATEDLL) && QT_VERSION < 0x040600

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works for me.

[hassenman]

Hi ,

i tried all the tricks mentioned above, none worked !
Any solution ?

Regards,

[Uwe]

Simply remove the offending line in qwt_valuelist.h

Uwe

[hassenman]

Thanks Uwe,

I tried to comment out the line, still getting the same compilation error

C:/qwt-5.1.2/../../Qt/2009.05/qt/include/QtCore/../../src/corelib/tools/qhash.h:875: error: call of overloaded 'qHash(const double&)' is ambiguous

#if defined(QWT_TEMPLATEDLL)
 
#if QT_VERSION < 0x040300
// Some compilers have problems, 
// without a qHash(double) implementation
#include <qset.h>
#include <qvector.h>
inline uint qHash(double key) { return uint(key); }
#endif
 
// MOC_SKIP_BEGIN
template class QWT_EXPORT QList<double>;
// MOC_SKIP_END
 
#endif // QWT_TEMPLATEDLL

#if defined(QWT_TEMPLATEDLL)

#if QT_VERSION < 0x040300
// Some compilers have problems, 
// without a qHash(double) implementation
#include <qset.h>
#include <qvector.h>
inline uint qHash(double key) { return uint(key); }
#endif

// MOC_SKIP_BEGIN
template class QWT_EXPORT QList<double>;
// MOC_SKIP_END

#endif // QWT_TEMPLATEDLL

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How can i check if QT_VERSION is taking the correct value ?

Is there any other workaround for this issue

Regards,

[Uwe]

I tried to comment out the line, still getting the same compilation error...

Then try harder: a compiler can't fail at a line, that has been removed.

More explicite: the offending line is the line exporting the template, but you can remove the complete QWT_TEMPLATEDLL scope ( or use qwt_valuelist.h from SVN 5.2 branch. )

Uwe

[Jore]

Im' having the same problem but in another file qhash.h. Can someone summon up, simple english, how to work around ambiguous qhash call?

c:/tools/Qt/2010.01/qt/include/QtCore/../../src/corelib/tools/qhash.h:875: error: call of overloaded 'qHash(const double&)' is ambiguous

Getting the same problem both on commandline and QT Creator
QT 4.6.1 2010.01
QWT 5.2.0
g++ 4.4.0 (gcc)

brg
Jore

[Uwe]

svn co https://qwt.svn.sourceforge.net/svnroot/qwt/branches/qwt-5.2

[OverTheOCean]

SOLUTION

comment line 48 in the qwt_valuelish.h"
//template class QWT_EXPORT QList<double>;

no need to export this symbol !~!

Michael