Change warning to error for nowarn_bif_clash compiler directive

4 files changed, 43 insertions, 52 deletions

diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl
index adee8795b2..935c2de253 100644
--- a/erts/preloaded/src/erlang.erl
+++ b/erts/preloaded/src/erlang.erl
@@ -44,7 +44,14 @@
 -deprecated([hash/2]).
 -deprecated([concat_binary/1]).
 
--compile(nowarn_bif_clash).
+% Get rid of autoimports of spawn to avoid clashes with ourselves.
+-compile({no_auto_import,[spawn/1]}).
+-compile({no_auto_import,[spawn/4]}).
+-compile({no_auto_import,[spawn_link/1]}).
+-compile({no_auto_import,[spawn_link/4]}).
+-compile({no_auto_import,[spawn_opt/2]}).
+-compile({no_auto_import,[spawn_opt/4]}).
+-compile({no_auto_import,[spawn_opt/5]}).
 
 %%--------------------------------------------------------------------------
 
diff --git a/lib/compiler/doc/src/compile.xml b/lib/compiler/doc/src/compile.xml
index 3a70f6277b..e1f24b602d 100644
--- a/lib/compiler/doc/src/compile.xml
+++ b/lib/compiler/doc/src/compile.xml
@@ -355,51 +355,34 @@
 
           <tag><c>nowarn_bif_clash</c></tag>
           <item>
-            <p>By default, the compiler will issue an error or warning
-            when replacing an auto-imported BIF. For local functions
-            having names clashing with an auto-imported BIF, the error
-            or warning is issued whenever it is called without using a
-            module prefix. For explicitly imported functions, the
-            error or warning will be issued as soon as it's imported
-            (regardless of calls). If the auto-imported BIF was present
-            before OTP R14A it will be a fatal error to override it,
-            otherwise only a warning will be issued.</p>
+            <p>This option is removed, it will generate a fatal error if used.</p>
 
 	    <warning>
 	    <p>Beginning with R14A, the compiler no longer calls the
 	    auto-imported BIF if the name clashes with a local or
 	    explicitly imported function and a call without explicit
 	    module name is issued. Instead the local or imported
-	    function is called. Use of <c>nowarn_bif_clash</c> makes a
+	    function is called. Still accepting <c>nowarn_bif_clash</c> would makes a
 	    module calling functions clashing with autoimported BIFs
 	    compile with both the old and new compilers, but with
-	    completely different semantics, why a warning is always
-	    issued if any code uses this option.</p>
+	    completely different semantics, why the option was removed.</p>
 
 	    <p>The use of this option has always been strongly discouraged.
-	    From OTP R14A and forward it's also deprecated.</p>
-	    <p>The only module who actually could have some legitimate use for
-	    this option is the module <c>erlang</c>, which in
-	    itself contains auto-imported functions, other modules
-	    should never use it.</p>
+	    From OTP R14A and forward it's an error to use it.</p>
 	    <p>To resolve BIF clashes, use explicit module names or the
-	    <c>{no_auto_import,[F/A]}</c> directive.</p>
-	    <p><c>nowarn_bif_clash</c> <em>will</em> be removed in a future release.</p>
+	    <c>{no_auto_import,[F/A]}</c> compiler directive.</p>
 	    </warning>
           </item>
 
           <tag><c>{nowarn_bif_clash, FAs}</c></tag>
           <item>
-            <p>Turns off warnings as <c>nowarn_bif_clash</c> but only
-	      for the mentioned local functions. <c>FAs</c> is a tuple
-	      <c>{Name,Arity}</c> or a list of such tuples.</p>
+            <p>This option is removed, it will generate a fatal error if used.</p>
+
 	    <warning>
 	    <p>The use of this option has always been strongly discouraged.
-	    From OTP R14A and forward it's also deprecated and a warning will be issued
-	    whenever it is used.</p>
+	    From OTP R14A and forward it's an error to use it.</p>
 	    <p>To resolve BIF clashes, use explicit module names or the
-	    <c>{no_auto_import,[F/A]}</c> directive instead.</p>
-	    <p><c>nowarn_bif_clash</c> <em>will</em> be removed in a future release.</p>
+	    <c>{no_auto_import,[F/A]}</c> compiler directive.</p>
 	    </warning>
           </item>
 
diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl
index 631ad0c1e3..29a949432b 100644
--- a/lib/stdlib/src/erl_lint.erl
+++ b/lib/stdlib/src/erl_lint.erl
@@ -163,8 +163,8 @@ format_error({bad_nowarn_unused_function,{F,A}}) ->
     io_lib:format("function ~w/~w undefined", [F,A]);
 format_error({bad_nowarn_bif_clash,{F,A}}) ->
     io_lib:format("function ~w/~w undefined", [F,A]);
-format_error(deprecated_nowarn_bif_clash) ->
-    io_lib:format("compile directive nowarn_bif_clash is deprecated,~n"
+format_error(disallowed_nowarn_bif_clash) ->
+    io_lib:format("compile directive nowarn_bif_clash is no longer allowed,~n"
 		  " - use explicit module names or -compile({no_auto_import, [F/A]})", []);
 format_error({bad_nowarn_deprecated_function,{M,F,A}}) ->
     io_lib:format("~w:~w/~w is not a deprecated function", [M,F,A]);
@@ -553,7 +553,7 @@ forms(Forms0, St0) ->
     Forms = eval_file_attribute(Forms0, St0),
     Locals = local_functions(Forms),
     AutoImportSuppressed = auto_import_suppressed(St0#lint.compile),
-    StDeprecated = deprecated_compile_flags(Forms,St0),
+    StDeprecated = disallowed_compile_flags(Forms,St0),
     %% Line numbers are from now on pairs {File,Line}.
     St1 = includes_qlc_hrl(Forms, StDeprecated#lint{locals = Locals,
 						    no_auto = AutoImportSuppressed}),
@@ -762,22 +762,23 @@ not_deprecated(Forms, St0) ->
     St1 = func_line_warning(bad_nowarn_deprecated_function, Bad, St0),
     St1#lint{not_deprecated = ordsets:from_list(Nowarn)}.
 
-deprecated_compile_flags(Forms, St0) ->
+%% The nowarn_bif_clash directive is not only deprecated, it's actually an error from R14A
+disallowed_compile_flags(Forms, St0) ->
     %% There are (still) no line numbers in St0#lint.compile.
-    Warnings0 =  [ {St0#lint.file,{L,erl_lint,deprecated_nowarn_bif_clash}} ||
+    Errors0 =  [ {St0#lint.file,{L,erl_lint,disallowed_nowarn_bif_clash}} ||
 		    {attribute,[{line,{_,L}}],compile,nowarn_bif_clash} <- Forms ],
-    Warnings1 = [ {St0#lint.file,{L,erl_lint,deprecated_nowarn_bif_clash}} ||
+    Errors1 = [ {St0#lint.file,{L,erl_lint,disallowed_nowarn_bif_clash}} ||
 		    {attribute,[{line,{_,L}}],compile,{nowarn_bif_clash, {_,_}}} <- Forms ],
     Disabled = (not is_warn_enabled(bif_clash, St0)),
-    Warnings = if
-		   Disabled andalso Warnings0 =:= [] ->
-		       [{St0#lint.file,{erl_lint,deprecated_nowarn_bif_clash}} | St0#lint.warnings];
+    Errors = if
+		   Disabled andalso Errors0 =:= [] ->
+		       [{St0#lint.file,{erl_lint,disallowed_nowarn_bif_clash}} | St0#lint.errors];
                    Disabled ->
-		       Warnings0 ++ Warnings1 ++ St0#lint.warnings;
+		       Errors0 ++ Errors1 ++ St0#lint.errors;
 		   true ->
-		       Warnings1 ++ St0#lint.warnings
+		       Errors1 ++ St0#lint.errors
 	       end,
-    St0#lint{warnings=Warnings}.
+    St0#lint{errors=Errors}.
 
 %% post_traversal_check(Forms, State0) -> State.
 %% Do some further checking after the forms have been traversed and
diff --git a/lib/stdlib/test/erl_lint_SUITE.erl b/lib/stdlib/test/erl_lint_SUITE.erl
index 4a366f6a28..8fe7881081 100644
--- a/lib/stdlib/test/erl_lint_SUITE.erl
+++ b/lib/stdlib/test/erl_lint_SUITE.erl
@@ -1785,7 +1785,7 @@ otp_5362(Config) when is_list(Config) ->
                       {16,erl_lint,{field_name_is_variable,ok,'Var'}}]}},
 
 	  %% Nowarn_bif_clash has changed behaviour as local functions
-	  %% nowdays supersede auto-imported BIFs, why nowarn_bif_clash in itself generates a warning
+	  %% nowdays supersede auto-imported BIFs, why nowarn_bif_clash in itself generates an error
 	  %% (OTP-8579) /PaN
           {otp_5362_4,
            <<"-compile(nowarn_deprecated_function).
@@ -1810,8 +1810,8 @@ otp_5362(Config) when is_list(Config) ->
                   spawn(A).
            ">>,
            {[nowarn_unused_function]},
-           {warnings,
-            [{2,erl_lint,deprecated_nowarn_bif_clash}]}},
+	   {errors,
+            [{2,erl_lint,disallowed_nowarn_bif_clash}],[]}},
 
           %% The special nowarn_X are not affected by general warn_X.
           {otp_5362_6,
@@ -1824,8 +1824,8 @@ otp_5362(Config) when is_list(Config) ->
            {[nowarn_unused_function, 
              warn_deprecated_function, 
              warn_bif_clash]},
-           {warnings,
-            [{2,erl_lint,deprecated_nowarn_bif_clash}]}},
+           {errors,
+            [{2,erl_lint,disallowed_nowarn_bif_clash}],[]}},
 
           {otp_5362_7,
            <<"-export([spawn/1]).
@@ -1840,10 +1840,10 @@ otp_5362(Config) when is_list(Config) ->
                   spawn(A).
            ">>,
            {[nowarn_unused_function]},
-           {error,[{4,erl_lint,{bad_nowarn_bif_clash,{spawn,2}}}],
-            [{3,erl_lint,deprecated_nowarn_bif_clash},
-	     {4,erl_lint,deprecated_nowarn_bif_clash},
-	     {5,erl_lint,{bad_nowarn_deprecated_function,{3,hash,-1}}},
+           {error,[{3,erl_lint,disallowed_nowarn_bif_clash},
+		   {4,erl_lint,disallowed_nowarn_bif_clash},
+		   {4,erl_lint,{bad_nowarn_bif_clash,{spawn,2}}}],
+            [{5,erl_lint,{bad_nowarn_deprecated_function,{3,hash,-1}}},
              {5,erl_lint,{bad_nowarn_deprecated_function,{erlang,hash,-1}}},
              {5,erl_lint,{bad_nowarn_deprecated_function,{{a,b,c},hash,-1}}}]}
            },
@@ -1882,8 +1882,8 @@ otp_5362(Config) when is_list(Config) ->
            {[nowarn_unused_function,
              warn_deprecated_function,
              warn_bif_clash]},
-           {warnings,
-            [{2,erl_lint,deprecated_nowarn_bif_clash}]}}
+           {errors,
+            [{2,erl_lint,disallowed_nowarn_bif_clash}],[]}}
 
           ],
 
@@ -2409,7 +2409,7 @@ bif_clash(Config) when is_list(Config) ->
            [],
 	   {errors,[{2,erl_lint,{call_to_redefined_old_bif,{size,1}}}],[]}},
 
-	  %% Verify that (some) warnings can be turned off.
+	  %% Verify that warnings can not be turned off in the old way.
 	  {clash2,
            <<"-export([t/1,size/1]).
               t(X) ->
@@ -2425,7 +2425,7 @@ bif_clash(Config) when is_list(Config) ->
               abs(X) -> erlang:abs(X).
              ">>,
 	   {[nowarn_unused_function,nowarn_bif_clash]},
-	   {warnings,[{erl_lint,deprecated_nowarn_bif_clash}]}},
+	   {errors,[{erl_lint,disallowed_nowarn_bif_clash}],[]}},
 	  %% As long as noone calls an overridden BIF, it's totally OK
 	  {clash3,
            <<"-export([size/1]).