Correct warnings and errors for auto-imported bif clashes

warn_unused_import works correctly (does not give warnings when overridden).
Local call in guard gives its own error pointing out the local/imported
  function.
Use of the phrase "overridden auto-imported bif" instead of "redefined
  auto-imported bif" in textual error messages.

3 files changed, 32 insertions, 12 deletions

diff --git a/lib/compiler/test/error_SUITE.erl b/lib/compiler/test/error_SUITE.erl
index 0874225a62..ec58a0761e 100644
--- a/lib/compiler/test/error_SUITE.erl
+++ b/lib/compiler/test/error_SUITE.erl
@@ -127,7 +127,7 @@ bif_clashes(Config) when is_list(Config) ->
              ">>,
            [],
           {error,
-           [{4,erl_lint,illegal_guard_expr}],
+           [{4,erl_lint,{illegal_guard_local_call,{length,1}}}],
            []} }],
     ?line [] = run2(Config, Ts3),
     Ts4 = [{bif_clashes9,
@@ -140,7 +140,7 @@ bif_clashes(Config) when is_list(Config) ->
              ">>,
            [],
           {error,
-           [{5,erl_lint,illegal_guard_expr}],
+           [{5,erl_lint,{illegal_guard_local_call,{length,1}}}],
            []} }],
     ?line [] = run2(Config, Ts4),
 
diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl
index 6bbb52ebae..9452572e49 100644
--- a/lib/stdlib/src/erl_lint.erl
+++ b/lib/stdlib/src/erl_lint.erl
@@ -197,19 +197,19 @@ format_error({define_import,{F,A}}) ->
 format_error({unused_function,{F,A}}) ->
     io_lib:format("function ~w/~w is unused", [F,A]);
 format_error({call_to_redefined_bif,{F,A}}) ->
-    io_lib:format("ambiguous call of redefined auto-imported BIF ~w/~w~n"
+    io_lib:format("ambiguous call of overridden auto-imported BIF ~w/~w~n"
 		  " - use erlang:~w/~w or \"-compile({no_auto_import,[~w/~w]}).\" "
 		  "to resolve name clash", [F,A,F,A,F,A]);
 format_error({call_to_redefined_old_bif,{F,A}}) ->
-    io_lib:format("ambiguous call of redefined pre R14 auto-imported BIF ~w/~w~n"
+    io_lib:format("ambiguous call of overridden pre R14 auto-imported BIF ~w/~w~n"
 		  " - use erlang:~w/~w or \"-compile({no_auto_import,[~w/~w]}).\" "
 		  "to resolve name clash", [F,A,F,A,F,A]);
 format_error({redefine_old_bif_import,{F,A}}) ->
-    io_lib:format("import directive redefines pre R14 auto-imported BIF ~w/~w~n"
+    io_lib:format("import directive overrides pre R14 auto-imported BIF ~w/~w~n"
 		  " - use \"-compile({no_auto_import,[~w/~w]}).\" "
 		  "to resolve name clash", [F,A,F,A]);
 format_error({redefine_bif_import,{F,A}}) ->
-    io_lib:format("import directive redefines auto-imported BIF ~w/~w~n"
+    io_lib:format("import directive overrides auto-imported BIF ~w/~w~n"
 		  " - use \"-compile({no_auto_import,[~w/~w]}).\" to resolve name clash", [F,A,F,A]);
 
 format_error({deprecated, MFA, ReplacementMFA, Rel}) ->
@@ -231,6 +231,9 @@ format_error(illegal_pattern) -> "illegal pattern";
 format_error(illegal_bin_pattern) ->
     "binary patterns cannot be matched in parallel using '='";
 format_error(illegal_expr) -> "illegal expression";
+format_error({illegal_guard_local_call, {F,A}}) -> 
+    io_lib:format("call to local/imported function ~w/~w is illegal in guard",
+		  [F,A]);
 format_error(illegal_guard_expr) -> "illegal guard expression";
 %% --- exports ---
 format_error({explicit_export,F,A}) ->
@@ -1811,7 +1814,13 @@ gexpr({call,Line,{atom,_La,F},As}, Vt, St0) ->
 		false -> {Asvt,add_error(Line, {explicit_export,F,A}, St1)}
 	    end;
         false ->
-	    {Asvt,add_error(Line, illegal_guard_expr, St1)}
+	    case is_local_function(St1#lint.locals,{F,A}) orelse
+		is_imported_function(St1#lint.imports,{F,A}) of
+		true ->
+		    {Asvt,add_error(Line, {illegal_guard_local_call,{F,A}}, St1)};
+		_ ->
+		    {Asvt,add_error(Line, illegal_guard_expr, St1)}
+	    end
     end;
 gexpr({call,Line,{remote,_Lr,{atom,_Lm,erlang},{atom,_Lf,F}},As}, Vt, St0) ->
     {Asvt,St1} = gexpr_list(As, Vt, St0),
@@ -2076,12 +2085,14 @@ expr({call,Line,{atom,La,F},As}, Vt, St0) ->
     IsAutoBif = erl_internal:bif(F, A),
     AutoSuppressed = is_autoimport_suppressed(St2#lint.no_auto,{F,A}),
     Warn = is_warn_enabled(bif_clash, St2) and (not bif_clash_specifically_disabled(St2,{F,A})),
-    case ((not IsLocal) andalso IsAutoBif andalso (not AutoSuppressed)) of
+    Imported = imported(F, A, St2),
+    case ((not IsLocal) andalso (Imported =:= no) andalso 
+	  IsAutoBif andalso (not AutoSuppressed)) of
         true ->
 	    St3 = deprecated_function(Line, erlang, F, As, St2),
 	    {Asvt,St3};
         false ->
-            {Asvt,case imported(F, A, St2) of
+            {Asvt,case Imported of
                       {yes,M} ->
                           St3 = check_remote_function(Line, M, F, As, St2),
                           U0 = St3#lint.usage,
diff --git a/lib/stdlib/test/erl_lint_SUITE.erl b/lib/stdlib/test/erl_lint_SUITE.erl
index 01f494ee38..d0c0d68b4a 100644
--- a/lib/stdlib/test/erl_lint_SUITE.erl
+++ b/lib/stdlib/test/erl_lint_SUITE.erl
@@ -2252,7 +2252,7 @@ otp_5878(Config) when is_list(Config) ->
                    {15,erl_lint,{undefined_field,r3,q}},
                    {17,erl_lint,{undefined_field,r,q}},
                    {21,erl_lint,illegal_guard_expr},
-                   {23,erl_lint,illegal_guard_expr}],
+                   {23,erl_lint,{illegal_guard_local_call,{l,0}}}],
            []} = 
         run_test2(Config, Ill1, [warn_unused_record]),
 
@@ -2492,7 +2492,7 @@ bif_clash(Config) when is_list(Config) ->
                 binary:part(B,X,Y).
              ">>,
 	   [],
-	   {errors,[{3,erl_lint,illegal_guard_expr}],[]}},
+	   {errors,[{3,erl_lint,{illegal_guard_local_call,{binary_part,2}}}],[]}},
           %% no_auto_import is not like nowarn_bif_clash, it actually removes the autoimport
 	  {clash9,
            <<"-export([x/1]).
@@ -2599,7 +2599,16 @@ bif_clash(Config) when is_list(Config) ->
                  binary_part(A,B,C+1).
              ">>,
 	   [],
-	   {errors,[{4,erl_lint,illegal_guard_expr}],[]}}
+	   {errors,[{4,erl_lint,illegal_guard_expr}],[]}},
+	  %% Not with local functions either
+	  {clash20,
+           <<"-export([binary_port/3]).
+              -import(x,[binary_part/3]).
+              binary_port(A,B,C) ->
+                 binary_part(A,B,C).
+             ">>,
+	   [warn_unused_import],
+	   {warnings,[{2,erl_lint,{redefine_bif_import,{binary_part,3}}}]}}
 	 ],
 
     ?line [] = run(Config, Ts),