Created attachment 432446 [details] build.log bz2 emerge =dev-python/PyQt5-5.5.1 result: ... (truncated , see build log) /usr/lib/gcc/x86_64-pc-linux-gnu/5.3.0/../../../../lib64/libQt5Xml.so: undefined reference to `QByteArray::clear()@Qt_5' /usr/lib/gcc/x86_64-pc-linux-gnu/5.3.0/../../../../lib64/libQt5Xml.so: undefined reference to `operator<(QString const&, QString const&)@Qt_5' /usr/lib/gcc/x86_64-pc-linux-gnu/5.3.0/../../../../lib64/libQt5Xml.so: undefined reference to `QMapNodeBase::nextNode() const@Qt_5' /usr/lib/gcc/x86_64-pc-linux-gnu/5.3.0/../../../../lib64/libQt5Xml.so: undefined reference to `QString::append(QLatin1String)@Qt_5' /usr/lib/gcc/x86_64-pc-linux-gnu/5.3.0/../../../../lib64/libQt5Xml.so: undefined reference to `QRegExp::indexIn(QString const&, int, QRegExp::CaretMode) const@Qt_5'
Created attachment 432448 [details] emerge --info
There's some disagreement between this: Qt v5.5.1 (Open Source) is being used. and this: /usr/lib/gcc/x86_64-pc-linux-gnu/5.3.0/../../../../lib64/libQt5Xml.so: undefined reference to `qt_version_tag@Qt_5.6' So, what versions of qtcore:5 and qtxml:5 do you have installed?
qtcore-5.5.1-r1 and qtxml-5.6.0
That's not possible unless your dependency tree is broken (you have unsatisfied deps), which makes this bug invalid.