Teach erl_lint to better override BIFs with local functions and imports

Added only a few testcases in compiler:error_SUITE and guard_SUITE

The new behaviour of warnings and errors when overriding autoimported BIF's:

Bifs that were autoimported before R14 are dangerous because old code
using them and overriding them in exports can start behaving
differently. For newly added autoimports this can't happen to the new
code that wants to (or dont want to) use them, why only warnings are
added for the BIFs autoimported after the compilator change. Errors
are issued only for code that could have worked in one way in R13 and
now will behave in a different way.

If overriding autoimport with local function:
- if explicit -compile directive supresses autoimport
	-> no message
  else
	- if called from inside module
		- if pre R14 autoimported bif
	     		-> error
                  else
			-> warning
	  else
             	-> no message
If overriding autoimport with import directive
- if explicit -compile directive supresses autoimport
	-> no message
  else (regardless of actual usage)
	- if pre R14 autoimported bif
	     	-> error
          else
		-> warning

Calls of local functions or imports overriding autoimported functions
(either post R14 or by using explicit -compile supressions of
autoimport) always goes to the local function or the imported.

The compileation errors are added to not let code like this silently
and disastrously change its semantic (probably to an infinite loop)
between R13 and R14:

----------
-module(m).

-export([length/1]).

length(X) ->
	...
	Y = length(Z),
	....
----------

The user has to select if he/she wants to call length in 'erlang' explicitly
or if the overriding semantics is desired, in which case the -compile
directive has to be used.

-compile({no_auto_import,[F/A]}). Is added to allow to override the
autoimports so that code gets unanbiguous. The directive will remove
an autoimport even if there is no local function or import overriding,
because any other behaviour would be inconsistent and confusing.

record_info and module_info can never be overridden.

1 files changed, 159 insertions, 7 deletions

diff --git a/lib/compiler/test/error_SUITE.erl b/lib/compiler/test/error_SUITE.erl
index 4530313bb0..c34dacb1bf 100644
--- a/lib/compiler/test/error_SUITE.erl
+++ b/lib/compiler/test/error_SUITE.erl
@@ -21,11 +21,133 @@
 -include("test_server.hrl").
 
 -export([all/1,
-	 head_mismatch_line/1,warnings_as_errors/1]).
+	 head_mismatch_line/1,warnings_as_errors/1, bif_clashes/1]).
 
 all(suite) ->
     test_lib:recompile(?MODULE),
-    [head_mismatch_line,warnings_as_errors].
+    [head_mismatch_line,warnings_as_errors,bif_clashes].
+
+
+bif_clashes(Config) when is_list(Config) ->
+    Ts = [{bif_clashes,
+           <<"
+              -export([t/0]).
+              t() ->
+                 length([a,b,c]).
+
+              length(X) ->
+               erlang:length(X).
+             ">>,
+           [return_warnings],
+	   {error,
+	    [{4, erl_lint,{redefine_old_bif,{length,1}}}], []} }],
+    ?line [] = run(Config, Ts),
+    Ts1 = [{bif_clashes,
+           <<"
+              -export([t/0]).
+              -import(x,[length/1]).
+              t() ->
+                 length([a,b,c]).
+             ">>,
+           [return_warnings],
+	    {error,
+	     [{3, erl_lint,{redefine_old_bif_import,{length,1}}}], []} }],
+    ?line [] = run(Config, Ts1),
+    Ts00 = [{bif_clashes,
+           <<"
+              -export([t/0]).
+              -compile({no_auto_import,[length/1]}).
+              t() ->
+                 length([a,b,c]).
+
+              length(X) ->
+               erlang:length(X).
+             ">>,
+           [return_warnings],
+	   []}],
+    ?line [] = run(Config, Ts00),
+    Ts11 = [{bif_clashes,
+           <<"
+              -export([t/0]).
+              -compile({no_auto_import,[length/1]}).
+              -import(x,[length/1]).
+              t() ->
+                 length([a,b,c]).
+             ">>,
+           [return_warnings],
+	    []}],
+    ?line [] = run(Config, Ts11),
+    Ts000 = [{bif_clashes,
+           <<"
+              -export([t/0]).
+              t() ->
+                 binary_part(<<1,2,3,4>>,1,2).
+
+              binary_part(X,Y,Z) ->
+               erlang:binary_part(X,Y,Z).
+             ">>,
+           [return_warnings],
+	   {warning,
+	    [{4, erl_lint,{redefine_bif,{binary_part,3}}}]} }],
+    ?line [] = run(Config, Ts000),
+    Ts111 = [{bif_clashes,
+           <<"
+              -export([t/0]).
+              -import(x,[binary_part/3]).
+              t() ->
+                  binary_part(<<1,2,3,4>>,1,2).
+             ">>,
+           [return_warnings],
+	    {warning,
+	     [{3, erl_lint,{redefine_bif_import,{binary_part,3}}}]} }],
+    ?line [] = run(Config, Ts111),
+    Ts2 = [{bif_clashes,
+           <<"
+              -export([t/0]).
+              -compile({no_auto_import,[length/1]}).
+              -import(x,[length/1]).
+              t() ->
+                 length([a,b,c]).
+              length(X) ->
+                 erlang:length(X).
+             ">>,
+           [],
+          {error,
+           [{7,erl_lint,{define_import,{length,1}}}],
+           []} }],
+    ?line [] = run2(Config, Ts2),
+    Ts3 = [{bif_clashes,
+           <<"
+              -export([t/1]).
+              -compile({no_auto_import,[length/1]}).
+              t(X) when length(X) > 3 ->
+                 length([a,b,c]).
+              length(X) ->
+                 erlang:length(X).
+             ">>,
+           [],
+          {error,
+           [{4,erl_lint,illegal_guard_expr}],
+           []} }],
+    ?line [] = run2(Config, Ts3),
+    Ts4 = [{bif_clashes,
+           <<"
+              -export([t/1]).
+              -compile({no_auto_import,[length/1]}).
+              -import(x,[length/1]).
+              t(X) when length(X) > 3 ->
+                 length([a,b,c]).
+             ">>,
+           [],
+          {error,
+           [{5,erl_lint,illegal_guard_expr}],
+           []} }],
+    ?line [] = run2(Config, Ts4),
+
+    ok.
+
+
+
 
 %% Tests that a head mismatch is reported on the correct line (OTP-2125).
 head_mismatch_line(Config) when is_list(Config) ->
@@ -49,7 +171,7 @@ warnings_as_errors(Config) when is_list(Config) ->
                  A = unused,
                  ok.
              ">>,
-           [warnings_as_errors],
+           [export_all,warnings_as_errors],
           {error,
            [],
            [{3,erl_lint,{unused_var,'A'}}]} }],
@@ -70,6 +192,24 @@ run(Config, Tests) ->
         end,
     lists:foldl(F, [], Tests).
 
+run2(Config, Tests) ->
+    F = fun({N,P,Ws,E}, BadL) ->
+                case catch filter(run_test(Config, P, Ws)) of
+                    E ->
+                        BadL;
+                    Bad ->
+                        ?t:format("~nTest ~p failed. Expected~n  ~p~n"
+                                  "but got~n  ~p~n", [N, E, Bad]),
+			fail()
+                end
+        end,
+    lists:foldl(F, [], Tests).
+
+filter({error,Es,_Ws}) ->
+    {error,Es,[]};
+filter(X) ->
+    X.
+
 
 %% Compiles a test module and returns the list of errors and warnings.
 
@@ -78,17 +218,29 @@ run_test(Conf, Test0, Warnings) ->
     ?line DataDir = ?config(priv_dir, Conf),
     ?line Test = ["-module(errors_test). ", Test0],
     ?line File = filename:join(DataDir, Filename),
-    ?line Opts = [binary,export_all,return|Warnings],
+    ?line Opts = [binary,return_errors|Warnings],
     ?line ok = file:write_file(File, Test),
 
     %% Compile once just to print all errors and warnings.
-    ?line compile:file(File, [binary,export_all,report|Warnings]),
+    ?line compile:file(File, [binary,report|Warnings]),
 
     %% Test result of compilation.
     ?line Res = case compile:file(File, Opts) of
-		    {error,[{_File,Es}],Ws} ->
+		    {ok,errors_test,_,[{_File,Ws}]} ->
+			%io:format("compile:file(~s,~p) ->~n~p~n",
+			%	  [File,Opts,Ws]),
+			{warning,Ws};
+		    {ok,errors_test,_,[]} ->
+			%io:format("compile:file(~s,~p) ->~n~p~n",
+			%	  [File,Opts,Ws]),
+			[];
+		    {error,[{XFile,Es}],Ws} = _ZZ when is_list(XFile) ->
+			%io:format("compile:file(~s,~p) ->~n~p~n",
+			%	  [File,Opts,_ZZ]),
 			{error,Es,Ws};
-		    {error,Es,[{_File,Ws}]} ->
+		    {error,Es,[{_File,Ws}]} = _ZZ->
+			%io:format("compile:file(~s,~p) ->~n~p~n",
+			%	  [File,Opts,_ZZ]),
 			{error,Es,Ws}
 		end,
     file:delete(File),