change from post-purging modules after checking their module info to

pre-purging before checking to facilitate long do chains

src/rebar_erlc_compiler.erl

@@ -260,10 +260,10 @@ opts_changed(Opts, Target) ->
     Basename = filename:basename(Target, ".beam"),
     Dirname = filename:dirname(Target),
     ObjectFile = filename:join([Dirname, Basename]),
+    _ = purge(list_to_atom(Basename)),
     case code:load_abs(ObjectFile) of
         {module, Mod} ->
             Compile = Mod:module_info(compile),
-            _ = purge(Mod),
             lists:sort(Opts) =/= lists:sort(proplists:get_value(options,
                                                                 Compile));
         {error, nofile} -> false
@@ -273,9 +273,7 @@ purge(Mod) ->
     %% remove old code if necessary
     _ = code:purge(Mod),
     %% move current code to old
-    true = code:delete(Mod),
-    %% remove new old code
-    _ = code:purge(Mod).
+    _ = code:delete(Mod).
 
 check_erlcinfo(_Config, #erlcinfo{vsn=?ERLCINFO_VSN}) ->
     ok;

src/rebar_otp_app.erl

@@ -167,18 +167,22 @@ ebin_modules(App, Dir) ->
 
 beam_src(Beam) ->
     try
+        Mod = list_to_atom(filename:basename(Beam, ".beam")),
+        _ = purge(Mod),
         {module, Mod} = code:load_abs(filename:rootname(Beam, ".beam")),
         Compile = Mod:module_info(compile),
-        %% completely purge module so any other attempts to load it succeed
-        _ = code:purge(Mod),
-        _ = code:delete(Mod),
-        _ = code:purge(Mod),
         proplists:get_value(source, Compile, [])
     catch
         error:undef -> [];
         error:nofile -> []
     end.
 
+purge(Mod) ->
+    %% remove old code if necessary
+    _ = code:purge(Mod),
+    %% move current code to old
+    _ = code:delete(Mod).
+
 ensure_registered(AppData) ->
     case lists:keyfind(registered, 1, AppData) of
         false ->

test/rebar_compile_SUITE.erl

@@ -11,7 +11,8 @@
          build_checkout_deps/1,
          recompile_when_opts_change/1,
          dont_recompile_when_opts_dont_change/1,
-         dont_recompile_yrl_or_xrl/1]).
+         dont_recompile_yrl_or_xrl/1,
+         purge_before_load/1]).
 
 -include_lib("common_test/include/ct.hrl").
 -include_lib("eunit/include/eunit.hrl").
@@ -33,7 +34,7 @@ all() ->
     [build_basic_app, build_release_apps,
      build_checkout_apps, build_checkout_deps,
      recompile_when_opts_change, dont_recompile_when_opts_dont_change,
-     dont_recompile_yrl_or_xrl].
+     dont_recompile_yrl_or_xrl, purge_before_load].
 
 build_basic_app(Config) ->
     AppDir = ?config(apps, Config),
@@ -183,3 +184,13 @@ dont_recompile_yrl_or_xrl(Config) ->
     NewModTime = filelib:last_modified(XrlBeam),
 
     ?assert(ModTime == NewModTime).
+
+purge_before_load(Config) ->
+    AppDir = ?config(apps, Config),
+
+    Name = rebar_test_utils:create_random_name("app1_"),
+    Vsn = rebar_test_utils:create_random_vsn(),
+    rebar_test_utils:create_app(AppDir, Name, Vsn, [kernel, stdlib]),
+
+    Tasks = ["do", "compile,compile,compile"],
+    rebar_test_utils:run_and_check(Config, [], Tasks, {ok, [{app, Name}]}).