Hi Holger,

I added libosmocore commit 7c942ba1475a366cc7c8a129fbdd335166ce21c6 during the camp as at the simtrace/osmocombb/openbsc workshop, several participants could not build the respective software packages.

This behavior was observed by Kevin and me, and adding subdir-objects resolved the problem. Due to the hectic nature of a workshop where everyone is waiting for the build to succeed on the system of all participants we did not have time to record the specific distribution versions at that time.

On Debian unstable with autoconf 2.50 / automake 1.15, the build generates the following warnings: =============== src/gsm/Makefile.am:15: warning: source file 'milenage/aes-encblock.c' is in a subdirectory, src/gsm/Makefile.am:15: but option 'subdir-objects' is disabled automake: warning: possible forward-incompatibility. automake: At least a source file is in a subdirectory, but the 'subdir-objects' automake: automake option hasn't been enabled. For now, the corresponding output automake: object file(s) will be placed in the top-level directory. However, automake: this behaviour will change in future Automake versions: they will automake: unconditionally cause object files to be placed in the same subdirectory automake: of the corresponding sources. automake: You are advised to start using 'subdir-objects' option throughout your automake: project, to avoid future incompatibilities. ===============

The project still builds afterwards on this Debian system, so indeed it is just a warning. However, the warning quite clearly indicates that the use of subdir-objects is not optional in the future!

So I'm not sure your revert of the assciated commit is the right way to proceed.

The point seems to be that 'make distclean' wants to remove the generated objects for the tests, but the latter only are compiled when 'make check' is used, but not in the default build.

Any ideas?