Bug#831442: mpich: Broken /usr/lib/libmpich.so.12 symlink, depending on installation order

[Thibaut Paumard]

Control: severity -1 serious

Dear Nicholas,

Le 16/07/2016 07:23, Nicholas Breen a écrit :
> A symlink /usr/lib/libmpich.so.12 is created only depending on what order the
> packages libmpich12 and libmpich-dev are installed in, apparently requiring
> libmpich-dev to be unpacked before libmpich12 is configured.

Thanks, it's actually due to a very old and known bug in ldconfig and
honestly I don't think that it is going to be fixed anytime soon:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=249122
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=224450

What happens is that if libmpich is installed before libopenmpi, then
libmpi.so (indirectly) points to
/usr/lib/x86_64-linux-gnu/libmpich.so.12.1.0
So the SONAME of libmpi.so is libmpich.so.12, and ldconfig creates the
corresponding symlink.

When libopenmpi is then installed, libmpi.so ceases to point to
libmpich, but the libmpich.so.12 link continues to exist, and indirectly
points to /usr/lib/openmpi/lib/libmpi.so!

I don't know how to do it, but the mpich package (and the openmpi
package?) should attempt to make sure that this link is not created or
is removed whenever libmpi.so stops pointing to libmpich.

As already mentioned, the autobuilders now default to installing
libmpich first. A workaround (for the autobuilders!) would be to
forcibly remove the /usr/lib/libmpich.so.12 symlink upon installation of
libopenmpi.

I think this bug is potentially very harmful (with wrongly link binaries
and FTBFSes) and warrants a serious severity.

Kind regards, Thibaut.