Merge branch 'cf/compile_warning_as_error' into ccase/r13b04_dev

* cf/compile_warning_as_error:
  Add option -Werror in erlc(1)
  compile: add flag warnings_as_errors to treat warnings as errors
  compile.erl: remove trailing whitespace

OTP-8382  The -Werror option for erlc and the compiler option
          warnings_as_errors will cause warnings to be treated as errors.
          (Thanks to Christopher Faulet.)

3 files changed, 70 insertions, 35 deletions

diff --git a/lib/compiler/doc/src/compile.xml b/lib/compiler/doc/src/compile.xml
index c39c9b25eb..daa686bc56 100644
--- a/lib/compiler/doc/src/compile.xml
+++ b/lib/compiler/doc/src/compile.xml
@@ -4,7 +4,7 @@
 <erlref>
   <header>
     <copyright>
-      <year>1996</year><year>2009</year>
+      <year>1996</year><year>2010</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -13,12 +13,12 @@
       compliance with the License. You should have received a copy of the
       Erlang Public License along with this software. If not, it can be
       retrieved online at http://www.erlang.org/.
-    
+
       Software distributed under the License is distributed on an "AS IS"
       basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
       the License for the specific language governing rights and limitations
       under the License.
-    
+
     </legalnotice>
 
     <title>compile</title>
@@ -212,6 +212,12 @@
               success.</p>
           </item>
 
+          <tag><c>warnings_as_errors</c></tag>
+          <item>
+            <p>Causes warnings to be treated as errors. This option is supported
+            since R13B04.</p>
+          </item>
+
           <tag><c>return</c></tag>
           <item>
             <p>This is a short form for both <c>return_errors</c> and
diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl
index e725083a9f..58e147d508 100644
--- a/lib/compiler/src/compile.erl
+++ b/lib/compiler/src/compile.erl
@@ -1,19 +1,19 @@
 %%
 %% %CopyrightBegin%
-%% 
-%% Copyright Ericsson AB 1996-2009. All Rights Reserved.
-%% 
+%%
+%% Copyright Ericsson AB 1996-2010. All Rights Reserved.
+%%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
 %% compliance with the License. You should have received a copy of the
 %% Erlang Public License along with this software. If not, it can be
 %% retrieved online at http://www.erlang.org/.
-%% 
+%%
 %% Software distributed under the License is distributed on an "AS IS"
 %% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 %% the License for the specific language governing rights and limitations
 %% under the License.
-%% 
+%%
 %% %CopyrightEnd%
 %%
 %% Purpose: Run the Erlang compiler.
@@ -302,7 +302,7 @@ os_process_size() ->
 	    list_to_integer(lib:nonl(Size));
 	_ ->
 	    0
-    end.	    
+    end.
 
 run_tc({Name,Fun}, St) ->
     Before0 = statistics(runtime),
@@ -318,17 +318,30 @@ run_tc({Name,Fun}, St) ->
     Val.
 
 comp_ret_ok(#compile{code=Code,warnings=Warn0,module=Mod,options=Opts}=St) ->
-    Warn = messages_per_file(Warn0),
-    report_warnings(St#compile{warnings = Warn}),
-    Ret1 = case member(binary, Opts) andalso not member(no_code_generation, Opts) of
-	       true -> [Code];
-	       false -> []
-	   end,
-    Ret2 = case member(return_warnings, Opts) of
-	       true -> Ret1 ++ [Warn];
-	       false -> Ret1
-	   end,
-    list_to_tuple([ok,Mod|Ret2]).
+    case member(warnings_as_errors, Opts) andalso length(Warn0) > 0 of
+        true ->
+            case member(report_warnings, Opts) of
+                true ->
+		    io:format("~p: warnings being treated as errors\n",
+			      [?MODULE]);
+                false ->
+		    ok
+            end,
+            comp_ret_err(St);
+        false ->
+            Warn = messages_per_file(Warn0),
+            report_warnings(St#compile{warnings = Warn}),
+            Ret1 = case member(binary, Opts) andalso
+		       not member(no_code_generation, Opts) of
+                       true -> [Code];
+                       false -> []
+                   end,
+            Ret2 = case member(return_warnings, Opts) of
+                       true -> Ret1 ++ [Warn];
+                       false -> Ret1
+                   end,
+            list_to_tuple([ok,Mod|Ret2])
+    end.
 
 comp_ret_err(#compile{warnings=Warn0,errors=Err0,options=Opts}=St) ->
     Warn = messages_per_file(Warn0),
@@ -344,18 +357,18 @@ comp_ret_err(#compile{warnings=Warn0,errors=Err0,options=Opts}=St) ->
 messages_per_file(Ms) ->
     T = lists:sort([{File,M} || {File,Messages} <- Ms, M <- Messages]),
     PrioMs = [erl_scan, epp, erl_parse],
-    {Prio0, Rest} = 
+    {Prio0, Rest} =
         lists:mapfoldl(fun(M, A) ->
                                lists:partition(fun({_,{_,Mod,_}}) -> Mod =:= M;
                                                   (_) -> false
                                                end, A)
                        end, T, PrioMs),
-    Prio = lists:sort(fun({_,{L1,_,_}}, {_,{L2,_,_}}) -> L1 =< L2 end, 
+    Prio = lists:sort(fun({_,{L1,_,_}}, {_,{L2,_,_}}) -> L1 =< L2 end,
                       lists:append(Prio0)),
     flatmap(fun mpf/1, [Prio, Rest]).
 
 mpf(Ms) ->
-    [{File,[M || {F,M} <- Ms, F =:= File]} || 
+    [{File,[M || {F,M} <- Ms, F =:= File]} ||
 	File <- lists:usort([F || {F,_} <- Ms])].
 
 %% passes(form|file, [Option]) -> [{Name,PassFun}]
@@ -495,14 +508,14 @@ select_passes([List|Ps], Opts) when is_list(List) ->
 
 select_cond(Flag, ShouldBe, Pass, Ps, Opts) ->
     ShouldNotBe = not ShouldBe,
-    case member(Flag, Opts) of 
+    case member(Flag, Opts) of
 	ShouldBe    -> select_passes([Pass|Ps], Opts);
 	ShouldNotBe -> select_passes(Ps, Opts)
     end.
 
 %% select_list_passes([Pass], Opts) -> {done,[Pass]} | {not_done,[Pass]}
 %%  Evaluate all conditions having to do with listings in the list of
-%%  passes. 
+%%  passes.
 
 select_list_passes(Ps, Opts) ->
     select_list_passes_1(Ps, Opts, []).
@@ -782,7 +795,7 @@ clean_parse_transforms_1([F|Fs], Acc) ->
     clean_parse_transforms_1(Fs, [F|Acc]);
 clean_parse_transforms_1([], Acc) -> reverse(Acc).
 
-transforms(Os) -> [ M || {parse_transform,M} <- Os ]. 
+transforms(Os) -> [ M || {parse_transform,M} <- Os ].
 
 transform_module(#compile{options=Opt,code=Code0}=St0) ->
     %% Extract compile options from code into options field.
@@ -815,7 +828,7 @@ foldl_transform(St, [T|Ts]) ->
     end;
 foldl_transform(St, []) -> {ok,St}.
 
-get_core_transforms(Opts) -> [M || {core_transform,M} <- Opts]. 
+get_core_transforms(Opts) -> [M || {core_transform,M} <- Opts].
 
 core_transforms(St) ->
     %% The options field holds the complete list of options at this
@@ -1264,7 +1277,7 @@ listing(Ext, St) ->
 listing(LFun, Ext, St) ->
     Lfile = outfile(St#compile.base, Ext, St#compile.options),
     case file:open(Lfile, [write,delayed_write]) of
-	{ok,Lf} -> 
+	{ok,Lf} ->
             Code = restore_expanded_types(Ext, St#compile.code),
 	    LFun(Lf, Code),
 	    ok = file:close(Lf),
diff --git a/lib/compiler/test/error_SUITE.erl b/lib/compiler/test/error_SUITE.erl
index 477730c3ac..cdd2434b25 100644
--- a/lib/compiler/test/error_SUITE.erl
+++ b/lib/compiler/test/error_SUITE.erl
@@ -1,19 +1,19 @@
 %%
 %% %CopyrightBegin%
-%% 
-%% Copyright Ericsson AB 1998-2009. All Rights Reserved.
-%% 
+%%
+%% Copyright Ericsson AB 1998-2010. All Rights Reserved.
+%%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
 %% compliance with the License. You should have received a copy of the
 %% Erlang Public License along with this software. If not, it can be
 %% retrieved online at http://www.erlang.org/.
-%% 
+%%
 %% Software distributed under the License is distributed on an "AS IS"
 %% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 %% the License for the specific language governing rights and limitations
 %% under the License.
-%% 
+%%
 %% %CopyrightEnd%
 %%
 -module(error_SUITE).
@@ -21,11 +21,11 @@
 -include("test_server.hrl").
 
 -export([all/1,
-	 head_mismatch_line/1,r11b_binaries/1]).
+	 head_mismatch_line/1,r11b_binaries/1,warnings_as_errors/1]).
 
 all(suite) ->
     test_lib:recompile(?MODULE),
-    [head_mismatch_line,r11b_binaries].
+    [head_mismatch_line,r11b_binaries,warnings_as_errors].
 
 %% Tests that a head mismatch is reported on the correct line (OTP-2125).
 head_mismatch_line(Config) when is_list(Config) ->
@@ -73,6 +73,20 @@ r11b_binaries(Config) when is_list(Config) ->
     ?line [] = run(Config, Ts),
     ok.
 
+warnings_as_errors(Config) when is_list(Config) ->
+    Ts = [{warnings_as_errors,
+           <<"
+               t() ->
+                 A = unused,
+                 ok.
+             ">>,
+           [warnings_as_errors],
+          {error,
+           [],
+           [{3,erl_lint,{unused_var,'A'}}]} }],
+    ?line [] = run(Config, Ts),
+    ok.
+
 
 run(Config, Tests) ->
     F = fun({N,P,Ws,E}, BadL) ->
@@ -104,6 +118,8 @@ run_test(Conf, Test0, Warnings) ->
     %% Test result of compilation.
     ?line Res = case compile:file(File, Opts) of
 		    {error,[{_File,Es}],Ws} ->
+			{error,Es,Ws};
+		    {error,Es,[{_File,Ws}]} ->
 			{error,Es,Ws}
 		end,
     file:delete(File),