Remove ?NO_APP, use atom no_app

This fixes:

  edoc_lib.erl:804: Function get_doc_env/1 has no local return
  edoc_lib.erl:805: The call edoc_lib:get_doc_env
           ([],
            [],
            Opts :: any()) breaks the contract
            (App, Modules, Options) -> edoc:env()
               when
                   App :: atom(),
                   Modules :: [module()],
                   Options :: proplist()
  edoc_run.erl:135: The created fun has no local return
  done in 0m7.25s

The first empty list in the call to edoc_lib:get_doc_env/3 above is ?NO_APP.
The atom `no_app` remains human-readable after the code is compiled,
whereas the macro name gets erased.

4 files changed, 15 insertions, 24 deletions

diff --git a/lib/edoc/include/edoc_doclet.hrl b/lib/edoc/include/edoc_doclet.hrl
index c15ba13aad..40ed77cff9 100644
--- a/lib/edoc/include/edoc_doclet.hrl
+++ b/lib/edoc/include/edoc_doclet.hrl
@@ -26,14 +26,12 @@
 %% Author contact: carlsson.richard@gmail.com
 %% =====================================================================
 
--define(NO_APP, []).
-
 -record(doclet_context, {dir = "",
 			 env,
 			 opts = []}).
 
 -record(doclet_gen, {sources = [],
-		     app = ?NO_APP,
+		     app = no_app,
 		     modules = []}).
 
 -record(doclet_toc, {paths,
diff --git a/lib/edoc/src/edoc.erl b/lib/edoc/src/edoc.erl
index 24740942e2..152eb9a1d4 100644
--- a/lib/edoc/src/edoc.erl
+++ b/lib/edoc/src/edoc.erl
@@ -381,7 +381,7 @@ run(Files, Opts0) ->
     Path = proplists:append_values(source_path, Opts),
     Ss = sources(Path, Opts),
     {Ss1, Ms} = expand_sources(expand_files(Files) ++ Ss, Opts),
-    App = proplists:get_value(application, Opts, ?NO_APP),
+    App = proplists:get_value(application, Opts, no_app),
     {App1, Ms1} = target_dir_info(Dir, App, Ms, Opts),
     Ms2 = edoc_lib:unique(lists:sort(Ms1)),
     Env = edoc_lib:get_doc_env(App1, Ms2, Opts),
@@ -453,7 +453,7 @@ target_dir_info(Dir, App, Ms, Opts) ->
 	    {App, Ms};
 	false ->
 	    {App1, Ms1} = edoc_lib:read_info_file(Dir),
-	    {if App == ?NO_APP -> App1;
+	    {if App == no_app -> App1;
 		true -> App
 	     end,
 	     Ms ++ Ms1}
diff --git a/lib/edoc/src/edoc_doclet.erl b/lib/edoc/src/edoc_doclet.erl
index ffeead89a3..8d51b3ce95 100644
--- a/lib/edoc/src/edoc_doclet.erl
+++ b/lib/edoc/src/edoc_doclet.erl
@@ -58,8 +58,7 @@
 -export_type([command/0,
 	      context/0,
 	      doclet_gen/0,
-	      doclet_toc/0,
-	      no_app/0]).
+	      doclet_toc/0]).
 
 -type command() :: doclet_gen()
 		 | doclet_toc().
@@ -70,14 +69,8 @@
 				   opts :: [term()]}.
 %% Context for doclets.
 
--type no_app() :: ?NO_APP.
-%% A value used to mark absence of an Erlang application
-%% context. Use the macro `NO_APP' defined in
-%% <a href="edoc_doclet.hrl">`edoc_doclet.hrl'</a>
-%% to produce this value.
-
 -type doclet_gen() :: #doclet_gen{sources :: [string()],
-				  app :: no_app() | atom(),
+				  app :: no_app | atom(),
 				  modules :: [module()]}.
 %% Doclet command.
 
@@ -181,7 +174,7 @@ gen(Sources, App, Modules, Ctxt) ->
 
 title(App, Options) ->
     proplists:get_value(title, Options,
-			if App == ?NO_APP ->
+			if App == no_app ->
 				"Overview";
 			   true ->
 				io_lib:fwrite("Application: ~ts", [App])
diff --git a/lib/edoc/src/edoc_lib.erl b/lib/edoc/src/edoc_lib.erl
index 9c894b3e0e..a460eca59c 100644
--- a/lib/edoc/src/edoc_lib.erl
+++ b/lib/edoc/src/edoc_lib.erl
@@ -608,7 +608,7 @@ write_file(Text, Dir, Name, Options) ->
 %% @private
 write_info_file(App, Modules, Dir) ->
     Ts = [{modules, Modules}],
-    Ts1 = if App =:= ?NO_APP -> Ts;
+    Ts1 = if App =:= no_app -> Ts;
 	     true -> [{application, App} | Ts]
 	  end,
     S0 = [io_lib:fwrite("~p.\n", [T]) || T <- Ts1],
@@ -636,7 +636,7 @@ read_file(File) ->
 %% Info files
 
 info_file_data(Ts) ->
-    App = proplists:get_value(application, Ts, ?NO_APP),
+    App = proplists:get_value(application, Ts, no_app),
     Ms = proplists:append_values(modules, Ts),
     {App, Ms}.
 
@@ -653,10 +653,10 @@ read_info_file(Dir) ->
 		{error, R} ->
 		    R1 = file:format_error(R),
 		    warning("could not read '~ts': ~ts.", [File, R1]),
-		    {?NO_APP, []}
+		    {no_app, []}
 	    end;
 	false ->
-	    {?NO_APP, []}
+	    {no_app, []}
     end.
 
 parse_info_file(Text, Name) ->
@@ -665,10 +665,10 @@ parse_info_file(Text, Name) ->
 	    info_file_data(Vs);
 	{error, eof} ->
 	    warning("unexpected end of file in '~ts'.", [Name]),
-	    {?NO_APP, []};
+	    {no_app, []};
 	{error, {_Line,Module,R}} ->
 	    warning("~ts: ~ts.", [Module:format_error(R), Name]),
-	    {?NO_APP, []}
+	    {no_app, []}
     end.
 
 parse_terms(Text) ->
@@ -796,7 +796,7 @@ get_doc_links(App, Modules, Opts) ->
     make_links(Ds1, D, D).
 
 make_links([{Dir, {App, Ms}} | Ds], A, M) ->
-    A1 = if App == ?NO_APP -> A;
+    A1 = if App == no_app -> A;
 	    true -> add_new(App, Dir, A)
 	 end,
     F = fun (K, D) -> add_new(K, Dir, D) end,
@@ -826,7 +826,7 @@ add_new(K, V, D) ->
 
 -spec get_doc_env(proplist()) -> edoc:env().
 get_doc_env(Opts) ->
-    get_doc_env([], [], Opts).
+    get_doc_env(no_app, [], Opts).
 
 %% @doc Creates an environment data structure used by parts of EDoc for
 %% generating references, etc. See {@link edoc:run/2} for a description
@@ -840,7 +840,7 @@ get_doc_env(Opts) ->
 %% DEFER-OPTIONS: edoc:run/2
 
 -spec get_doc_env(App, Modules, Options) -> edoc:env() when
-      App :: atom(),
+      App :: atom() | no_app,
       Modules :: [module()],
       Options :: proplist().
 get_doc_env(App, Modules, Opts) ->