QMAKE_PRL_LIBS contains wrong entries on Windows

The Problem

When building qtactiveqt against qtbase with MSVC, Qt6AxServer.prl contains the following:

QMAKE_PRL_LIBS = -lshell32 $$[QT_INSTALL_LIBS]/Qt6AxBase.lib -ladvapi32 -lgdi32 -lole32 -loleaut32 -luser32 Qt6Widgets Qt6Gui Qt6Core -lmpr -luserenv -ld3d11 -ldxgi -ldxguid

The entries for the modules from qtbase are incorrect. The line should be

QMAKE_PRL_LIBS = -lshell32 $$[QT_INSTALL_LIBS]/Qt6AxBase.lib -ladvapi32 -lgdi32 -lole32 -loleaut32 -luser32 $$[QT_INSTALL_LIBS]/Qt6Widgets.lib $$[QT_INSTALL_LIBS]/Qt6Gui.lib $$[QT_INSTALL_LIBS]/Qt6Core.lib -lmpr -luserenv -ld3d11 -ldxgi -ldxguid

Analysis

This is what happens:

• The libraries AxServer links against is determined by qt_collect_libs
• The full path to Qt6Widgets.dll is written into preliminary_prl_for_AxServer_step1_Release.prl
• QtFinishPrlFile.cmake is run to transform preliminary_prl_for_AxServer_step1_Release.prl into preliminary_prl_for_AxServer_step2_Release.prl
• QtFinishPrlFile.cmake fails to determine that Qt6Widgets.dll is a Qt module and writes it as just Qt6Widgets

And it fails to determine that this is a Qt module, because we check whether the library is below ${QT_LIB_DIRS} which contains ${CMAKE_INSTALL_PREFIX}/lib. Qt6Widgets.dll is in ${CMAKE_INSTALL_PREFIX}/bin, however.

This can be fixed in two ways:

• write the full path to Qt6Widgets.lib into preliminary_prl_for_AxServer_step1_Release.prl
• or pass the bin dir to QT_LIB_DIRS when creating the 2nd stage prl file