Merge branch 'zandra/stdlib/optional-callbacks/OTP-13801'

* zandra/stdlib/optional-callbacks/OTP-13801:
  wx: make wx_object callbacks optional
  stdlib: Make gen_fsm callbacks optional
  stdlib: Make gen_event callbacks optional
  stdlib: Make gen_server callbacks optional

3 files changed, 73 insertions, 35 deletions

diff --git a/lib/stdlib/src/gen_event.erl b/lib/stdlib/src/gen_event.erl
index 0aebf1bdc5..0c50b2aa08 100644
--- a/lib/stdlib/src/gen_event.erl
+++ b/lib/stdlib/src/gen_event.erl
@@ -109,7 +109,8 @@
       State :: term(),
       Status :: term().
 
--optional_callbacks([format_status/2]).
+-optional_callbacks(
+    [handle_info/2, terminate/2, code_change/3, format_status/2]).
 
 %%---------------------------------------------------------------------------
 
@@ -577,6 +578,10 @@ server_update(Handler1, Func, Event, SName) ->
 	    do_terminate(Mod1, Handler1, remove_handler, State,
 			 remove, SName, normal),
 	    no;
+        {'EXIT', {undef, [{Mod1, handle_info, [_,_], _}|_]}} ->
+            error_logger:warning_msg("** Undefined handle_info in ~p~n"
+                                     "** Unhandled message: ~p~n", [Mod1, Event]),
+           {ok, Handler1};
 	Other ->
 	    do_terminate(Mod1, Handler1, {error, Other}, State,
 			 Event, SName, crash),
@@ -698,9 +703,15 @@ server_call_update(Handler1, Query, SName) ->
     end.
 
 do_terminate(Mod, Handler, Args, State, LastIn, SName, Reason) ->
-    Res = (catch Mod:terminate(Args, State)),
-    report_terminate(Handler, Reason, Args, State, LastIn, SName, Res),
-    Res.
+    case erlang:function_exported(Mod, terminate, 2) of
+	true ->
+	    Res = (catch Mod:terminate(Args, State)),
+	    report_terminate(Handler, Reason, Args, State, LastIn, SName, Res),
+	    Res;
+	false ->
+	    report_terminate(Handler, Reason, Args, State, LastIn, SName, ok),
+	    ok
+    end.
 
 report_terminate(Handler, crash, {error, Why}, State, LastIn, SName, _) ->
     report_terminate(Handler, Why, State, LastIn, SName);
diff --git a/lib/stdlib/src/gen_fsm.erl b/lib/stdlib/src/gen_fsm.erl
index e925a75fe8..39a8fd42fe 100644
--- a/lib/stdlib/src/gen_fsm.erl
+++ b/lib/stdlib/src/gen_fsm.erl
@@ -169,7 +169,8 @@
       State :: term(),
       Status :: term().
 
--optional_callbacks([format_status/2]).
+-optional_callbacks(
+    [handle_info/3, terminate/3, code_change/4, format_status/2]).
 
 %%% ---------------------------------------------------
 %%% Starts a generic state machine.
@@ -466,6 +467,10 @@ handle_msg(Msg, Parent, Name, StateName, StateData, Mod, _Time) -> %No debug her
 					   StateName, NStateData, [])),
 	    reply(From, Reply),
 	    exit(R);
+        {'EXIT', {undef, [{Mod, handle_info, [_,_,_], _}|_]}} ->
+            error_logger:warning_msg("** Undefined handle_info in ~p~n"
+                                     "** Unhandled message: ~p~n", [Mod, Msg]),
+            loop(Parent, Name, StateName, StateData, Mod, infinity, []);
 	{'EXIT', What} ->
 	    terminate(What, Name, Msg, Mod, StateName, StateData, []);
 	Reply ->
@@ -540,24 +545,30 @@ reply(Name, {To, Tag}, Reply, Debug, StateName) ->
 -spec terminate(term(), _, _, atom(), _, _, _) -> no_return().
 
 terminate(Reason, Name, Msg, Mod, StateName, StateData, Debug) ->
-    case catch Mod:terminate(Reason, StateName, StateData) of
-	{'EXIT', R} ->
-	    FmtStateData = format_status(terminate, Mod, get(), StateData),
-	    error_info(R, Name, Msg, StateName, FmtStateData, Debug),
-	    exit(R);
-	_ ->
-	    case Reason of
-		normal ->
-		    exit(normal);
-		shutdown ->
-		    exit(shutdown);
- 		{shutdown,_}=Shutdown ->
- 		    exit(Shutdown);
+    case erlang:function_exported(Mod, terminate, 3) of
+	true ->
+	    case catch Mod:terminate(Reason, StateName, StateData) of
+		{'EXIT', R} ->
+		    FmtStateData = format_status(terminate, Mod, get(), StateData),
+		    error_info(R, Name, Msg, StateName, FmtStateData, Debug),
+		    exit(R);
 		_ ->
-                    FmtStateData = format_status(terminate, Mod, get(), StateData),
-		    error_info(Reason,Name,Msg,StateName,FmtStateData,Debug),
-		    exit(Reason)
-	    end
+		    ok
+	    end;
+	false ->
+	    ok
+    end,
+    case Reason of
+	normal ->
+	    exit(normal);
+	shutdown ->
+	    exit(shutdown);
+ 	{shutdown,_}=Shutdown ->
+ 	    exit(Shutdown);
+	_ ->
+	    FmtStateData1 = format_status(terminate, Mod, get(), StateData),
+	    error_info(Reason,Name,Msg,StateName,FmtStateData1,Debug),
+	    exit(Reason)
     end.
 
 error_info(Reason, Name, Msg, StateName, StateData, Debug) ->
diff --git a/lib/stdlib/src/gen_server.erl b/lib/stdlib/src/gen_server.erl
index 284810c971..8504af86f8 100644
--- a/lib/stdlib/src/gen_server.erl
+++ b/lib/stdlib/src/gen_server.erl
@@ -146,8 +146,8 @@
       State :: term(),
       Status :: term().
 
--optional_callbacks([format_status/2]).
-
+-optional_callbacks(
+    [handle_info/2, terminate/2, code_change/3, format_status/2]).
 
 %%%  -----------------------------------------------------------------
 %%% Starts a generic server.
@@ -602,6 +602,17 @@ try_dispatch(Mod, Func, Msg, State) ->
     catch
 	throw:R ->
 	    {ok, R};
+        error:undef = R when Func == handle_info ->
+            case erlang:function_exported(Mod, handle_info, 2) of
+                false ->
+                    error_logger:warning_msg("** Undefined handle_info in ~p~n"
+                                             "** Unhandled message: ~p~n",
+                                             [Mod, Msg]),
+                    {ok, {noreply, State}};
+                true ->
+                    Stacktrace = erlang:get_stacktrace(),
+                    {'EXIT', {R, Stacktrace}, {R, Stacktrace}}
+            end;
 	error:R ->
 	    Stacktrace = erlang:get_stacktrace(),
 	    {'EXIT', {R, Stacktrace}, {R, Stacktrace}};
@@ -625,17 +636,22 @@ try_handle_call(Mod, Msg, From, State) ->
     end.
 
 try_terminate(Mod, Reason, State) ->
-    try
-	{ok, Mod:terminate(Reason, State)}
-    catch
-	throw:R ->
-	    {ok, R};
-	error:R ->
-	    Stacktrace = erlang:get_stacktrace(),
-	    {'EXIT', {R, Stacktrace}, {R, Stacktrace}};
-	exit:R ->
-	    Stacktrace = erlang:get_stacktrace(),
-	    {'EXIT', R, {R, Stacktrace}}
+    case erlang:function_exported(Mod, terminate, 2) of
+	true ->
+	    try
+		{ok, Mod:terminate(Reason, State)}
+	    catch
+		throw:R ->
+		    {ok, R};
+		error:R ->
+		    Stacktrace = erlang:get_stacktrace(),
+		    {'EXIT', {R, Stacktrace}, {R, Stacktrace}};
+		exit:R ->
+		    Stacktrace = erlang:get_stacktrace(),
+		    {'EXIT', R, {R, Stacktrace}}
+	   end;
+	false ->
+	    {ok, ok}
     end.