rebar3-app-dependency

This directory has two sub-directories, each of which is a trivial Erlang application with four sub-applications. I made it to illustrate how the order of compilation for rebar3 depends on dependencies in the .app.src files, but not on their order in any application that depends on them.

rebar3-app-test has the following .app.src file:

{application, 'rebar3-app-test',
 [...
   {applications,
   [kernel,
    stdlib,
    app21, app13, app42, app34
   ]},
 ]}.

The four sub-apps each include only kernel and stdlib in their applications list. The build looks like this:

$ cd .../rebar3-app-test
$ ./rebar3 compile
===> Verifying dependencies...
===> Compiling app42
===> Compiling app34
===> Compiling app21
===> Compiling app13
===> Compiling rebar3-app-test

Note that the compile order does not match the order in the .app.src file.

rebar-related-app-test has the following .app.src file:

{application, 'rebar3-related-app-test',
 [...
  {applications,
   [kernel,
    stdlib
   ]},
 ]}.

Its four sub-applications depend on each other in a chain, where a->b means that a has b in the applications list in its .app.src file:

app34 -> app13 -> app42 -> app21

The build looks like this

$ cd .../rebar3-related-app-test
$ ./rebar3 compile
===> Verifying dependencies...
===> Compiling app21
===> Compiling app42
===> Compiling rebar3-related-app-test
===> Compiling app13
===> Compiling app34

Note that the dependencies changed the order of compilation of the sub-applications, but since the rebar3-related-app-test application depends on none of the sub-applications, it is compiled in a random place relative to them.

tristan said on #rebar that this is as designed.