mathgl: Upload new version 2.5

[Rafael Laboissière <rafael@debian.org>]

Hi,

The new upstream version 2.5 of MathGL has been recently released. I 
prepared the new version of the Debian package on the Git repo. If nobody 
objects, I will upload it. I am juste wondering whether it should be done 
to unstable or experimental. In this new upstream version, the upstream 
authors bumped (what they call) the "SOVERSION", such that all library 
binary packages produced by the mathgl source have to change names.

This will cause the new uploaded package to go through the NEW queue and 
will need a "mini-transition" involving the 3depict package (the only 
reverse-dependency on libmgl).

Now, the process of updating the mathgl package after such upstream 
"SOVERSION" bumps is pretty painful. This is caused by the very strange 
way in which upstream deals with the soversion. Indeed, a single 
"soversion" is defined in the CMakeLists.txt file:

    $ grep SOVERSION CMakeLists.txt | grep ^set
    set(MathGL_SOVERSION 7.6.0)

The defined variable (MathGL_SOVERSION) is then used to set the SOVERSION 
property of all libmgl* libraries:

    $ grep MathGL_SOVERSION CMakeLists.txt | grep set_target
            set_target_properties(${mgllib} PROPERTIES SOVERSION ${MathGL_SOVERSION})

We end up with a collection of shared libraries that have the same 
"SOVERSION":

    $ find debian/tmp -name \*.so.\*
    debian/tmp/usr/lib/libmgl-wnd.so.7.6.0
    debian/tmp/usr/lib/libmgl-mpi.so.7.6.0
    debian/tmp/usr/lib/libmgl-wx.so.7.6.0
    debian/tmp/usr/lib/libmgl-qt.so.7.6.0
    debian/tmp/usr/lib/libmgl.so.7.6.0
    debian/tmp/usr/lib/libmgl-qt5.so.7.6.0
    debian/tmp/usr/lib/libmgl-glut.so.7.6.0
    debian/tmp/usr/lib/libmgl-fltk.so.7.6.0

and this forces the changing of package names at each SOVERSION bump:

    $ grep ^Package: debian/control | grep 7.6
    Package: libmgl7.6.0
    Package: libmgl-mpi7.6.0
    Package: libmgl-wnd7.6.0
    Package: libmgl-glut7.6.0
    Package: libmgl-qt5-7.6.0
    Package: libmgl-fltk7.6.0
    Package: libmgl-wx7.6.0

This is pretty lame. Besides changing all package names and the names of 
the debian/libmgl*.install files, , we need to keep a ever-growing list 
of Replaces/Conflicts, for instance for the libmgl-glut7.6.0 package:

    Replaces: libmgl-glut5, libmgl-glut6.0.0, libmgl-glut7.1.0, libmgl-glut7.2.0,
     libmgl-glut7.4.0, libmgl-glut7.4.1, libmgl-glut7.5.0
    Conflicts: libmgl-glut5, libmgl-glut6.0.0, libmgl-glut7.1.0, libmgl-glut7.2.0,
     libmgl-glut7.4.0, libmgl-glut7.4.1, libmgl-glut7.5.0

IMHO, the scheme adopted by the upstream authors is not correct. First, 
the SOVERSION should be a single number, corresponding to the major part 
of the library version and not the composite major.minor.micro. Second, 
each individual library should have its own version/soversion, which 
should be bumped only when there are changes in it.

Anyway, I think that we are trapped in this strange package naming scheme 
for mathgl, unless the upstream authors change its way of setting 
soversion/version or we patch the upstream sources.

Best,

Rafael