[Kde-bindings] [Bug 145518] New: QtRuby - Qt::GridLayout.new crashes program; QT_NO_LAYOUT Smoke error

[Richard Dale]

On Wednesday 16 May 2007, Tomi Belan wrote:
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> http://bugs.kde.org/show_bug.cgi?id=145518
>            Summary: QtRuby - Qt::GridLayout.new crashes program;
>                     QT_NO_LAYOUT Smoke error
>            Product: bindings
>            Version: unspecified
>           Platform: Mandriva RPMs
>         OS/Version: Linux
>             Status: UNCONFIRMED
>           Severity: crash
>           Priority: NOR
>          Component: general
>         AssignedTo: kde-bindings kde org
>         ReportedBy: tomi.belan gmail com
>
>
> Version:           qt4-qtruby-1.4.7 (using KDE KDE 3.5.5)
> Installed from:    Mandriva RPMs
> Compiler:          gcc version 4.1.2 20070302 (prerelease)
> (4.1.2-1mdv2007.1) OS:                Linux
>
> The QtRuby tutorial at
> http://www.arachnoid.com/ruby/RubyGUIProject/index.html crashes (with
> segmentation fault). Fortunately, I found out what causes it: After
> debugging the program, I found out that it crashes when calling
> Qt::GridLayout.new. From QtRuby logs I found out that this function doesn't
> exist (has no "candidates"). (If needed, I may provide these logs.) I tried
> to recompile QtRuby from source (instead of using the RPM) and traced the
> bug to its source: while configure-ing, Smoke defined QT_NO_LAYOUTS. It was
> set by smoke/qt/qtguess.pl (auto-generated from qtguess.pl.in). The script
> tried to compile this program:
>
> #include <QtGui/qlayout.h>
> #include <QtCore/qfeatures.h>
>
> class QFoo: public QLayout
> {
> public:
> QFoo() {};
> ~QFoo() {};
> void addItem( QLayoutItem * ) { };
> QSize sizeHint() const { return QSize(); }
> void setGeometry( const QRect & ) { };
> QLayoutItem* itemAt(int) const {return (QLayoutItem*) NULL;}
> QLayoutItem* takeAt(int) {return (QLayoutItem*) NULL;}
> int QFoo::count() const {return 0;}     <---- this is line 14
> };
>
> int main( int argc, char ** argv)
> {
> QFoo foo;
> return 0;
> }
> (EOF)
>
> Compilation failed with this error:
>
> 28982-qtguess.cpp:14: error: extra qualification 'QFoo::' on member 'count'
>
> Obviously, this is just an error in the testing program and Qt layouts work
> as they should, so QT_NO_LAYOUTS shouldn't be defined.
>
> I think that maybe there are two separate bugs: 1. qtguess.pl(.in) has a
> wrong testing program for QT_NO_LAYOUTS, 2. QtRuby reacts with segmentation
> fault when a non-existent function (or just constructor?) is called.
The configure check has already been fixed in the KDE svn version of QtRuby, 
and so it will be in the next release. I'm not sure why it doesn't give an 
error message for the call to the missing constructor though.

-- Richard