bif_SUITE: Add test case for specs and BIF stubs

Rename the existing types/1 test case to erl_bif_types/1 to make
it clearer what it does. Also no longer test for missing type
information for BIFs (since it has become optional), but only
check that the information provided seems to be consistent.

Introduce the specs/1 test case to ensure that all BIFs have
specs.

Also introduce improper_bif_stubs/1 to check for proper stubs.
Since the BEAM loader will now silently allow stubs for BIFs, we
want to be particular about exactly what a stub look like, so that
an Erlang function is not unintentionally overridden by a BIF.

1 files changed, 125 insertions, 19 deletions

diff --git a/erts/emulator/test/bif_SUITE.erl b/erts/emulator/test/bif_SUITE.erl
index c7617d3b90..eaececdafa 100644
--- a/erts/emulator/test/bif_SUITE.erl
+++ b/erts/emulator/test/bif_SUITE.erl
@@ -25,7 +25,7 @@
 	 init_per_group/2,end_per_group/2,
 	 init_per_testcase/2,end_per_testcase/2,
 	 display/1, display_huge/0,
-	 types/1,
+	 erl_bif_types/1,specs/1,improper_bif_stubs/1,
 	 t_list_to_existing_atom/1,os_env/1,otp_7526/1,
 	 binary_to_atom/1,binary_to_existing_atom/1,
 	 atom_to_binary/1,min_max/1]).
@@ -33,7 +33,8 @@
 suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() -> 
-    [types, t_list_to_existing_atom, os_env, otp_7526,
+    [erl_bif_types, specs, improper_bif_stubs,
+     t_list_to_existing_atom, os_env, otp_7526,
      display,
      atom_to_binary, binary_to_atom, binary_to_existing_atom,
      min_max].
@@ -86,33 +87,28 @@ deeep(N,Acc) ->
 deeep(N) ->
     deeep(N,[hello]).
 
-
-types(Config) when is_list(Config) ->
+erl_bif_types(Config) when is_list(Config) ->
     c:l(erl_bif_types),
     case erlang:function_exported(erl_bif_types, module_info, 0) of
 	false ->
 	    %% Fail cleanly.
 	    ?line ?t:fail("erl_bif_types not compiled");
 	true ->
-	    types_1()
+	    erl_bif_types_1()
     end.
 
-types_1() ->
-    ?line List0 = erlang:system_info(snifs),
+erl_bif_types_1() ->
+    List0 = erlang:system_info(snifs),
 
     %% Ignore missing type information for hipe BIFs.
-    ?line List = [MFA || {M,_,_}=MFA <- List0, M =/= hipe_bifs],
+    List = [MFA || {M,_,_}=MFA <- List0, M =/= hipe_bifs],
 
-    case [MFA || MFA <- List, not known_types(MFA)] of
-	[] ->
-	    types_2(List);
-	BadTypes ->
-	    io:put_chars("No type information:\n"),
-	    io:format("~p\n", [lists:sort(BadTypes)]),
-	    ?line ?t:fail({length(BadTypes),bifs_without_types})
-    end.
+    KnownTypes = [MFA || MFA <- List, known_types(MFA)],
+    io:format("There are ~p BIFs with type information in erl_bif_types.",
+	      [length(KnownTypes)]),
+    erl_bif_types_2(KnownTypes).
 
-types_2(List) ->
+erl_bif_types_2(List) ->
     BadArity = [MFA || {M,F,A}=MFA <- List,
 		       begin
 			   Types = erl_bif_types:arg_types(M, F, A),
@@ -120,14 +116,14 @@ types_2(List) ->
 		       end],
     case BadArity of
 	[] ->
-	    types_3(List);
+	    erl_bif_types_3(List);
 	[_|_] ->
 	    io:put_chars("Bifs with bad arity\n"),
 	    io:format("~p\n", [BadArity]),
 	    ?line ?t:fail({length(BadArity),bad_arity})
     end.
 
-types_3(List) ->
+erl_bif_types_3(List) ->
     BadSmokeTest = [MFA || {M,F,A}=MFA <- List,
 			   begin
 			       try erl_bif_types:type(M, F, A) of
@@ -154,6 +150,89 @@ types_3(List) ->
 known_types({M,F,A}) ->
     erl_bif_types:is_known(M, F, A).
 
+specs(_) ->
+    List0 = erlang:system_info(snifs),
+
+    %% Ignore missing type information for hipe BIFs.
+    List1 = [MFA || {M,_,_}=MFA <- List0, M =/= hipe_bifs],
+
+    %% Ignore all operators.
+    List = [MFA || MFA <- List1, not is_operator(MFA)],
+
+    %% Extract specs from the abstract code for all BIFs.
+    Path = get_code_path(),
+    BifRel = sofs:relation(List, [{m,f,a}]),
+    BifModules = sofs:to_external(sofs:projection(1, BifRel)),
+    AbstrByModule = [extract_abstract(Mod, Path) || Mod <- BifModules],
+    Specs0 = [extract_specs(Mod, Abstr) ||
+		 {Mod,Abstr} <- AbstrByModule],
+    Specs = lists:append(Specs0),
+    BifSet = sofs:set(List, [function]),
+    SpecRel0 = sofs:relation(Specs, [{function,spec}]),
+    SpecRel = sofs:restriction(SpecRel0, BifSet),
+
+    %% Find BIFs without specs.
+    NoSpecs0 = sofs:difference(BifSet, sofs:domain(SpecRel)),
+    NoSpecs = sofs:to_external(NoSpecs0),
+    case NoSpecs of
+	[] ->
+	    ok;
+	[_|_] ->
+	    io:put_chars("The following BIFs don't have specs:\n"),
+	    [print_mfa(MFA) || MFA <- NoSpecs],
+	    ?t:fail()
+    end.
+
+is_operator({erlang,F,A}) ->
+    erl_internal:arith_op(F, A) orelse
+	erl_internal:bool_op(F, A) orelse
+	erl_internal:comp_op(F, A) orelse
+	erl_internal:list_op(F, A) orelse
+	erl_internal:send_op(F, A);
+is_operator(_) -> false.
+    
+extract_specs(M, Abstr) ->
+    [{make_mfa(M, Name),Spec} || {attribute,_,spec,{Name,Spec}} <- Abstr].
+
+make_mfa(M, {F,A}) -> {M,F,A};
+make_mfa(M, {M,_,_}=MFA) -> MFA.
+
+improper_bif_stubs(_) ->
+    Bifs0 = erlang:system_info(snifs),
+    Bifs = [MFA || {M,_,_}=MFA <- Bifs0, M =/= hipe_bifs],
+    Path = get_code_path(),
+    BifRel = sofs:relation(Bifs, [{m,f,a}]),
+    BifModules = sofs:to_external(sofs:projection(1, BifRel)),
+    AbstrByModule = [extract_abstract(Mod, Path) || Mod <- BifModules],
+    Funcs0 = [extract_functions(Mod, Abstr) ||
+		 {Mod,Abstr} <- AbstrByModule],
+    Funcs = lists:append(Funcs0),
+    BifSet = sofs:set(Bifs, [function]),
+    FuncRel0 = sofs:relation(Funcs, [{function,code}]),
+    FuncRel = sofs:restriction(FuncRel0, BifSet),
+    [check_stub(MFA, Body) || {MFA,Body} <- sofs:to_external(FuncRel)],
+    ok.
+
+extract_functions(M, Abstr) ->
+    [{{M,F,A},Body} || {function,_,F,A,Body} <- Abstr].
+
+check_stub({erlang,apply,3}, _) ->
+    ok;
+check_stub({_,F,A}, B) ->
+    try
+	[{clause,_,Args,[],Body}] = B,
+	A = length(Args),
+	[{call,_,{remote,_,{atom,_,erlang},{atom,_,nif_error}},[_]}] = Body
+    catch
+	_:_ ->
+	    io:put_chars("Invalid body for the following BIF stub:\n"),
+	    Func = {function,0,F,A,B},
+	    io:put_chars(erl_pp:function(Func)),
+	    io:nl(),
+	    io:put_chars("The body should be: erlang:nif_error(undef)"),
+	    ?t:fail()
+    end.
+
 t_list_to_existing_atom(Config) when is_list(Config) ->
     ?line all = list_to_existing_atom("all"),
     ?line ?MODULE = list_to_existing_atom(?MODULE_STRING),
@@ -442,3 +521,30 @@ min_max(Config) when is_list(Config) ->
     
 id(I) -> I.
 
+%% Get code path, including the path for the erts application.
+get_code_path() ->
+    case code:lib_dir(erts) of
+	{error,bad_name} ->
+	    Erts = filename:join([code:root_dir(),"erts","preloaded","ebin"]),
+	    [Erts|code:get_path()];
+	_ ->
+	    code:get_path()
+    end.
+
+which(Mod, Path) ->
+    which_1(atom_to_list(Mod) ++ ".beam", Path).
+
+which_1(Base, [D|Ds]) ->
+    Path = filename:join(D, Base),
+    case filelib:is_regular(Path) of
+	true -> Path;
+	false -> which_1(Base, Ds)
+    end.
+print_mfa({M,F,A}) ->
+    io:format("~p:~p/~p", [M,F,A]).
+
+extract_abstract(Mod, Path) ->
+    Beam = which(Mod, Path),
+    {ok,{Mod,[{abstract_code,{raw_abstract_v1,Abstr}}]}} =
+	beam_lib:chunks(Beam, [abstract_code]),
+    {Mod,Abstr}.