Make escript_incl_extra work with _checkouts

When developing `relx` and testing changes with `rebar3`, it is convenient to make `relx` a checkout dependency.

However, the current implementation of `escript_incl_extra` expects the output directory of `relx` to be under `_build/<profile>/lib/`, which is not the case if `relx` is a checkout dependency.

Instead of making a breaking change to `escript_incl_extra`, introduce a new config parameter instead.

rebar.config

@@ -25,10 +25,10 @@
 {escript_wrappers_windows, ["cmd", "powershell"]}.
 {escript_comment, "%%Rebar3 3.16.1\n"}.
 {escript_emu_args, "%%! +sbtu +A1\n"}.
-%% escript_incl_extra is for internal rebar-private use only.
+%% escript_incl_priv is for internal rebar-private use only.
 %% Do not use outside rebar. Config interface is not stable.
-{escript_incl_extra, [{"relx/priv/templates/*", "_build/default/lib/"},
-                      {"rebar/priv/templates/*", "_build/default/lib/"}]}.
+{escript_incl_priv, [{relx, "templates/*"},
+                     {rebar, "templates/*"}]}.
 
 {overrides, [{add, relx, [{erl_opts, [{d, 'RLX_LOG', rebar_log}]}]}]}.
 
@@ -67,10 +67,6 @@
             {bootstrap, []},
 
             {prod, [
-                {escript_incl_extra, [
-                    {"relx/priv/templates/*", "_build/prod/lib/"},
-                    {"rebar/priv/templates/*", "_build/prod/lib/"}
-                ]},
                 {erl_opts, [no_debug_info]},
                 {overrides, [
                     {override, erlware_commons, [

src/rebar_prv_escriptize.erl

@@ -206,10 +206,26 @@ get_app_beams(App, Path) ->
         load_files(Prefix, "*.app", Path).
 
 get_extra(State) ->
-    Extra = rebar_state:get(State, escript_incl_extra, []),
+    AllApps = rebar_state:all_deps(State) ++ rebar_state:project_apps(State),
+    InclPriv = rebar_state:get(State, escript_incl_priv, []),
+    InclPrivPaths = lists:map(fun(Entry) ->
+                                      resolve_incl_priv(Entry, AllApps)
+                              end, InclPriv),
+    % `escript_incl_extra` is kept for historical reasons as its internal use in
+    % rebar3 has been replaced with `escript_incl_priv`.
+    InclExtraPaths = rebar_state:get(State, escript_incl_extra, []),
     lists:foldl(fun({Wildcard, Dir}, Files) ->
                         load_files(Wildcard, Dir) ++ Files
-                end, [], Extra).
+                end, [], InclPrivPaths ++ InclExtraPaths).
+
+% Converts a wildcard path relative to an app (e.g., `priv/*`) into a wildcard
+% path with with the app name included (e.g., `relx/priv/*`).
+resolve_incl_priv({AppName, PrivWildcard}, AllApps) when is_atom(AppName) ->
+    {ok, AppInfo} =
+        rebar_app_utils:find(rebar_utils:to_binary(AppName), AllApps),
+    AppOutDir = rebar_app_info:out_dir(AppInfo),
+    Wildcard = filename:join([atom_to_list(AppName), "priv", PrivWildcard]),
+    {Wildcard, filename:dirname(AppOutDir)}.
 
 load_files(Wildcard, Dir) ->
     load_files("", Wildcard, Dir).