[Interest] building one of Qt's database plugins post-hoc

[René J.V. Bertin]

Hi,

The installation workflow I'm working on installs Qt (5.4.1) in a single pass, minus the QtWebEngine component, and minus all database plugins (and minus the docs and examples but that's irrelevant I hope).
The database plugins are to be provided as individual packages (MacPorts "ports"), like for instance the sqlite plugin (port:qt5-mac-sqlite3-plugin).

The build script I use is in place since Qt 4, and works with Qt 5.4.1 when I do a native build (64bit on a 64bit system): I extract the qtbase directory and the configure script from the qt-everywhere tarball, and then chdir into qtbase/src/plugins/sqldrivers/sqlite to execute `qmake -r` with the options required to point it to non-Qt libraries it might not find otherwise.

As said, this works for a native build. To do a 32bit build, the build script adds `-spec macx-clang-32` to the qmake arguments, but it is like that mkspec is ignored. The command is executed in a virgin source tree that was just extracted from the (original) tarball. When I use this same mkspec to configure any other project outside of the Qt source tree it is taken into account as expected. So it seems there is something in qtbase/src/plugins/sqldrivers/sqlite (or higher up in the same tree) that modifies qmake's behaviour.

What c/should I be looking for?

Thanks,
René