fix external (non-rebar3) project compile

Author: aboroska

src/rebar_fetch.erl

@@ -34,7 +34,7 @@ download_source(AppInfo, State)  ->
                 {true, AppInfo2} ->
                     rebar_app_info:is_available(AppInfo2, true);
                 false ->
-                    throw(?PRV_ERROR({dep_app_not_found, rebar_app_info:name(AppInfo1)}))
+                    rebar_app_info:is_available(AppInfo1, true)
             end;
         {error, Reason} ->
             throw(?PRV_ERROR(Reason))

src/rebar_prv_compile.erl

@@ -162,6 +162,10 @@ compile(State, Providers, AppInfo) ->
 
     AppInfo2 = rebar_hooks:run_all_hooks(AppDir, pre, ?ERLC_HOOK, Providers, AppInfo1, State),
 
+    %% For non-rebar3 built deps the proper app structure should be created by pre-hooks
+    %% by this time. Verify that.
+    ok = verify_app_structure(AppInfo2, AppDir),
+
     build_app(AppInfo2, State),
 
     AppInfo3 = rebar_hooks:run_all_hooks(AppDir, post, ?ERLC_HOOK, Providers, AppInfo2, State),
@@ -214,6 +218,14 @@ build_app(AppInfo, State) ->
             end
     end.
 
+verify_app_structure(AppInfo, AppDir) ->
+    case rebar_app_discover:find_app(AppInfo, AppDir, all) of
+      {true, _AppInfo1} ->
+        ok;
+      false ->
+        throw(?PRV_ERROR({dep_app_not_found, rebar_app_info:name(AppInfo)}))
+    end.
+
 update_code_paths(State, ProjectApps) ->
     ProjAppsPaths = paths_for_apps(ProjectApps),
     ExtrasPaths = paths_for_extras(State, ProjectApps),