[erlang-questions] Reltool error: "Module potentially included by two different applications"

[Eduard Sergeev]

Hi,

I was wondering what was the reason behind the following behaviour of reltool:

If my reltool.config uses default 'mod_cond' and 'incl_cond' options
and if one of my included applications has a module which also happens
to be a part of some application installed on my machine but NOT
included in my release `relltool:get_target_spec/1` returns:

{error, "Module <some_module> potentially included by two different
applications: <system_app> and <my_app>."}

Which is annoying since <system_app> is NOT a part of my release
(neither directly nor indirectly). Can't reltool actually figure out
that <system_app> will not be included in my release? Id that why it
is "potentially included"?

Anyway, in order to generate my release I have to either explicitly
exclude <system_app> via `{app, <system_app> [{incl_cond, exclude}]}`
which is ugly since this <system_app> is just happens to be installed
in 'lib' directory of the machine where I do the build (it may not be
installed on other build machines) and has nothing to do with my
release. The actual example: 'tsung-1.4.3' includes 'mochijson2'
module so I have a problem building my release which should include
'mochiweb' app on the machine that has 'tsung' installed (but not on
other machines).
Another option would be to change top-level 'incl_cond' from
{incl_cond, derived} to {incl_cond, exclude} and then manually include
all the application which I want to be a part my release which is
better (will work on any build machine) but still not great since it
has to be done manually (I want to rely on relltool to figure out the
dependencies).

So the question is why do we have such a situation? Why just a mere
presence of some application on the build machine lead to the above
reltool error?

Regards,
Eduard