ros-kinetic/qt_gui_cpp does not emerge cause of QT_INSTALL_LIBS not defined

[awesomebytes]

This may also happen to further packages that depend on qtcore. Like ros-kinetic/rviz.

The main thing is that dev-qt/qtcore on (at least) version 5.12 and 5.13 fail to substitute an environment variable in the file: $EPREFIX/usr/lib/libQt5Gui.prl (the variable is $$[QT_INSTALL_LIBS]).

The workaround is to substitute it with the actual path yourself after emerging dev-qt/qtcore.

I did this with:

qt_install_libs_path=`qmake -query QT_INSTALL_LIBS`; sed -i 's@$$\[QT_INSTALL_LIBS\]@'$qt_install_libs_path'@' $EPREFIX/usr/lib/libQt5Gui.prl

Kinda ugly workaround... I know. Reported in Gentoo bugtracker here: https://bugs.gentoo.org/702142

P.S.: Found the workaround from here: http://python.6.x6.nabble.com/Incorrect-Makefile-using-prl-files-from-Qt-5-12-4-td5255962.html