Friday, 18 March 2016

Re: Only one qt version on the Ubuntu Desktop iso?

On Fri, Mar 18, 2016 at 09:30:25PM +0000, Colin Watson wrote:
> On Fri, Mar 18, 2016 at 03:26:53PM -0400, Michael Hall wrote:
> > I know that appmenu-qt technically depends on qt4 being installed, but
> > if it will only be used by a qt4 app, and such an app would itself
> > depend on the qt4 packages, would there be any harm in making appmenu-qt
> > just *not* depend on qt4 packages itself?

> This kind of thing is indeed technically possible, but IME it's risky:
> if appmenu-qt should find itself with shared library linkage that
> requires a newer version of the library (which could happen for reasons
> as innocuous as a rebuild, if Qt were to change in certain kinds of
> ways), then it would be easy to end up with an appmenu-qt that required
> a newer version of Qt than was depended on by the applications in
> question and thus would fail to start.

> I guess the risk of this is probably low in this particular case since
> Qt 4 isn't in particularly active development, but my concern would be
> that this kind of trick has a habit of being copied into contexts where
> it might be riskier despite looking innocuous.

Exercise for the reader: take the substvars generated by dh_shlibdeps,
extract the relevant libraries and invert the version comparison to make it
a Breaks: against incompatible versions of libqt4 instead of a Depends: on
the required ones...

Steve Langasek Give me a lever long enough and a Free OS
Debian Developer to set it on, and I can move the world.
Ubuntu Developer