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BC break in 4.6 against previous 4.6

Published on Thursday November 12, 2009 by Thiago Macieira in C++ Qt Git KDE | Comments

To everyone using Qt 4.6 from the Git repository: be aware that I introduced a binary-incompatible change. This change is there to stay.

No, we're not breaking binary compatibility with Qt 4.5. This only affects previous Qt 4.6 versions.

Actually, this kind of change happens all the time. So why am I blogging about this specific change?

Well, the problem is that this change affects QHash, QMap and QVector. And those classes are inlined everywhere in Qt-using code. This means that, if you update Qt across that version, you must recompile all of the Qt-using code, from scratch (i.e., make clean). For KDE developers using trunk, that means recompiling all of KDE.

This change will be included in the upcoming Qt 4.6.0 Release Candidate.

Note: the change is in the 4.6 branch but hasn't reached the 4.6-stable branch yet. That also means it's not in kde-qt's 4.6-stable-patched branch yet. When you next update those stable branches, please remember to recompile everything.

PS: the stable branches aren't updating not because of Qt not building. It is buiding. The reason why is because our Continuous Integration system experiencing some technical difficulties, like Windows running out of memory, the Symbian buildsystem failing for no apparent reason, the powerful 8-core Mac machines being able to run only one testcase at a time, etc.

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