Merge branch 'bjorn/eliminate-sys_pre_expand/OTP-13856'

* bjorn/eliminate-sys_pre_expand/OTP-13856:
  Remove sys_pre_expand
  xref: Eliminate use of sys_pre_expand
  debugger: Eliminate use of sys_pre_expand
  compiler: Eliminate use of sys_pre_expand
  shell_SUITE: Eliminate references to sys_pre_expand in comments
  qlc_pt: Simplify code because of updated erl_expand_records
  Teach erl_expand_records to translate module-less calls
  erl_internal: Add add_predefined_functions/1
  cover: Remove always stale comment

4 files changed, 129 insertions, 44 deletions

diff --git a/lib/stdlib/src/erl_expand_records.erl b/lib/stdlib/src/erl_expand_records.erl
index ebcbc54ab1..ab47f05320 100644
--- a/lib/stdlib/src/erl_expand_records.erl
+++ b/lib/stdlib/src/erl_expand_records.erl
@@ -17,7 +17,8 @@
 %%
 %% %CopyrightEnd%
 %%
-%% Purpose : Expand records into tuples.
+%% Purpose: Expand records into tuples. Also add explicit module
+%% names to calls to imported functions and BIFs.
 
 %% N.B. Although structs (tagged tuples) are not yet allowed in the
 %% language there is code included in pattern/2 and expr/3 (commented out)
@@ -31,7 +32,7 @@
 
 -record(exprec, {compile=[],          % Compile flags
                  vcount=0,            % Variable counter
-                 imports=[],          % Imports
+		 calltype=#{},	      % Call types
                  records=dict:new(),  % Record definitions
                  strict_ra=[],        % strict record accesses
                  checked_ra=[]        % successfully accessed records
@@ -46,22 +47,34 @@
 %% erl_lint without errors.
 module(Fs0, Opts0) ->
     Opts = compiler_options(Fs0) ++ Opts0,
-    St0 = #exprec{compile = Opts},
+    Calltype = init_calltype(Fs0),
+    St0 = #exprec{compile = Opts, calltype = Calltype},
     {Fs,_St} = forms(Fs0, St0),
     Fs.
 
 compiler_options(Forms) ->
     lists:flatten([C || {attribute,_,compile,C} <- Forms]).
 
+init_calltype(Forms) ->
+    Locals = [{{Name,Arity},local} || {function,_,Name,Arity,_} <- Forms],
+    Ctype = maps:from_list(Locals),
+    init_calltype_imports(Forms, Ctype).
+
+init_calltype_imports([{attribute,_,import,{Mod,Fs}}|T], Ctype0) ->
+    true = is_atom(Mod),
+    Ctype = foldl(fun(FA, Acc) ->
+			  Acc#{FA=>{imported,Mod}}
+		  end, Ctype0, Fs),
+    init_calltype_imports(T, Ctype);
+init_calltype_imports([_|T], Ctype) ->
+    init_calltype_imports(T, Ctype);
+init_calltype_imports([], Ctype) -> Ctype.
+
 forms([{attribute,_,record,{Name,Defs}}=Attr | Fs], St0) ->
     NDefs = normalise_fields(Defs),
     St = St0#exprec{records=dict:store(Name, NDefs, St0#exprec.records)},
     {Fs1, St1} = forms(Fs, St),
     {[Attr | Fs1], St1};
-forms([{attribute,L,import,Is} | Fs0], St0) ->
-    St1 = import(Is, St0),
-    {Fs,St2} = forms(Fs0, St1),
-    {[{attribute,L,import,Is} | Fs], St2};
 forms([{function,L,N,A,Cs0} | Fs0], St0) ->
     {Cs,St1} = clauses(Cs0, St0),
     {Fs,St2} = forms(Fs0, St1),
@@ -334,8 +347,16 @@ expr({'receive',Line,Cs0,To0,ToEs0}, St0) ->
     {ToEs,St2} = exprs(ToEs0, St1),
     {Cs,St3} = clauses(Cs0, St2),
     {{'receive',Line,Cs,To,ToEs},St3};
-expr({'fun',_,{function,_F,_A}}=Fun, St) ->
-    {Fun,St};
+expr({'fun',Lf,{function,F,A}}=Fun0, St0) ->
+    case erl_internal:bif(F, A) of
+        true ->
+	    {As,St1} = new_vars(A, Lf, St0),
+	    Cs = [{clause,Lf,As,[],[{call,Lf,{atom,Lf,F},As}]}],
+	    Fun = {'fun',Lf,{clauses,Cs}},
+	    expr(Fun,  St1);
+	false ->
+	    {Fun0,St0}
+    end;
 expr({'fun',_,{function,_M,_F,_A}}=Fun, St) ->
     {Fun,St};
 expr({'fun',Line,{clauses,Cs0}}, St0) ->
@@ -352,14 +373,30 @@ expr({call,Line,{remote,_,{atom,_,erlang},{atom,_,is_record}},
 expr({call,Line,{tuple,_,[{atom,_,erlang},{atom,_,is_record}]},
       [A,{atom,_,Name}]}, St) ->
     record_test(Line, A, Name, St);
+expr({call,Line,{atom,_La,record_info},[_,_]=As0}, St0) ->
+    {As,St1} = expr_list(As0, St0),
+    record_info_call(Line, As, St1);
 expr({call,Line,{atom,_La,N}=Atom,As0}, St0) ->
     {As,St1} = expr_list(As0, St0),
     Ar = length(As),
-    case {N,Ar} =:= {record_info,2} andalso not imported(N, Ar, St1) of
-	true ->
-	    record_info_call(Line, As, St1);
-	false ->
-	    {{call,Line,Atom,As},St1}
+    NA = {N,Ar},
+    case St0#exprec.calltype of
+	#{NA := local} ->
+	    {{call,Line,Atom,As},St1};
+	#{NA := {imported,Module}} ->
+	    ModAtom = {atom,Line,Module},
+	    {{call,Line,{remote,Line,ModAtom,Atom},As},St1};
+	_ ->
+	    case erl_internal:bif(N, Ar) of
+		true ->
+		    ModAtom = {atom,Line,erlang},
+		    {{call,Line,{remote,Line,ModAtom,Atom},As},St1};
+		false ->
+		    %% Call to a module_info/0,1 or one of the
+		    %% pseudo-functions in the shell. Leave it as
+		    %% a local call.
+		    {{call,Line,Atom,As},St1}
+	    end
     end;
 expr({call,Line,{remote,Lr,M,F},As0}, St0) ->
     {[M1,F1 | As1],St1} = expr_list([M,F | As0], St0),
@@ -769,6 +806,13 @@ bin_element({bin_element,Line,Expr,Size,Type}, {Es,St0}) ->
                   end,
     {[{bin_element,Line,Expr1,Size1,Type} | Es],St2}.
 
+new_vars(N, L, St) -> new_vars(N, L, St, []).
+
+new_vars(N, L, St0, Vs) when N > 0 ->
+    {V,St1} = new_var(L, St0),
+    new_vars(N-1, L, St1, [V|Vs]);
+new_vars(0, _L, St, Vs) -> {Vs,St}.
+
 new_var(L, St0) ->
     {New,St1} = new_var_name(St0),
     {{var,L,New},St1}.
@@ -783,18 +827,6 @@ make_list(Ts, Line) ->
 call_error(L, R) ->
     {call,L,{remote,L,{atom,L,erlang},{atom,L,error}},[R]}.
 
-import({Mod,Fs}, St) ->
-    St#exprec{imports=add_imports(Mod, Fs, St#exprec.imports)};
-import(_Mod0, St) ->
-    St.
-
-add_imports(Mod, [F | Fs], Is) ->
-    add_imports(Mod, Fs, orddict:store(F, Mod, Is));
-add_imports(_, [], Is) -> Is.
-
-imported(F, A, St) ->
-    orddict:is_key({F,A}, St#exprec.imports).
-
 %%%
 %%% Replace is_record/3 in guards with matching if possible.
 %%%
diff --git a/lib/stdlib/src/erl_internal.erl b/lib/stdlib/src/erl_internal.erl
index 46059f42a5..5d6aa0ebe8 100644
--- a/lib/stdlib/src/erl_internal.erl
+++ b/lib/stdlib/src/erl_internal.erl
@@ -54,6 +54,8 @@
 
 -export([is_type/2]).
 
+-export([add_predefined_functions/1]).
+
 %%---------------------------------------------------------------------------
 
 %%  Erlang builtin functions allowed in guards.
@@ -569,3 +571,68 @@ is_type(term, 0) -> true;
 is_type(timeout, 0) -> true;
 is_type(tuple, 0) -> true;
 is_type(_, _) -> false.
+
+%%%
+%%% Add and export the pre-defined functions:
+%%%
+%%%   module_info/0
+%%%   module_info/1
+%%%   behaviour_info/1 (optional)
+%%%
+
+-spec add_predefined_functions(Forms) -> UpdatedForms when
+      Forms :: [erl_parse:abstract_form() | erl_parse:form_info()],
+      UpdatedForms :: [erl_parse:abstract_form() | erl_parse:form_info()].
+
+add_predefined_functions(Forms) ->
+    Forms ++ predefined_functions(Forms).
+
+predefined_functions(Forms) ->
+    Attrs = [{Name,Val} || {attribute,_,Name,Val} <- Forms],
+    {module,Mod} = lists:keyfind(module, 1, Attrs),
+    Callbacks = [Callback || {callback,Callback} <- Attrs],
+    OptionalCallbacks = get_optional_callbacks(Attrs),
+    Mpf1 = module_predef_func_beh_info(Callbacks, OptionalCallbacks),
+    Mpf2 = module_predef_funcs_mod_info(Mod),
+    Mpf = [erl_parse:new_anno(F) || F <- Mpf1++Mpf2],
+    Exp = [{F,A} || {function,_,F,A,_} <- Mpf],
+    [{attribute,0,export,Exp}|Mpf].
+
+get_optional_callbacks(Attrs) ->
+    L = [O || {optional_callbacks,O} <- Attrs, is_fa_list(O)],
+    lists:append(L).
+
+is_fa_list([{FuncName, Arity}|L])
+  when is_atom(FuncName), is_integer(Arity), Arity >= 0 ->
+    is_fa_list(L);
+is_fa_list([]) -> true;
+is_fa_list(_) -> false.
+
+module_predef_func_beh_info([], _) ->
+    [];
+module_predef_func_beh_info(Callbacks0, OptionalCallbacks) ->
+    Callbacks = [FA || {{_,_}=FA,_} <- Callbacks0],
+    List = make_list(Callbacks),
+    OptionalList = make_list(OptionalCallbacks),
+    [{function,0,behaviour_info,1,
+      [{clause,0,[{atom,0,callbacks}],[],[List]},
+       {clause,0,[{atom,0,optional_callbacks}],[],[OptionalList]}]}].
+
+make_list([]) -> {nil,0};
+make_list([{Name,Arity}|Rest]) ->
+    {cons,0,
+     {tuple,0,
+      [{atom,0,Name},
+       {integer,0,Arity}]},
+     make_list(Rest)}.
+
+module_predef_funcs_mod_info(Mod) ->
+    ModAtom = {atom,0,Mod},
+    [{function,0,module_info,0,
+      [{clause,0,[],[],
+        [{call,0,{remote,0,{atom,0,erlang},{atom,0,get_module_info}},
+          [ModAtom]}]}]},
+     {function,0,module_info,1,
+      [{clause,0,[{var,0,'X'}],[],
+        [{call,0,{remote,0,{atom,0,erlang},{atom,0,get_module_info}},
+          [ModAtom,{var,0,'X'}]}]}]}].
diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl
index 85b2816451..549179da68 100644
--- a/lib/stdlib/src/erl_parse.yrl
+++ b/lib/stdlib/src/erl_parse.yrl
@@ -1567,19 +1567,6 @@ anno_from_term(Term) ->
     map_anno(fun erl_anno:from_term/1, Term).
 
 %% Forms.
-%% Recognize what sys_pre_expand does:
-modify_anno1({'fun',A,F,{_,_,_}=Id}, Ac, Mf) ->
-    {A1,Ac1} = Mf(A, Ac),
-    {F1,Ac2} = modify_anno1(F, Ac1, Mf),
-    {{'fun',A1,F1,Id},Ac2};
-modify_anno1({named_fun,A,N,F,{_,_,_}=Id}, Ac, Mf) ->
-    {A1,Ac1} = Mf(A, Ac),
-    {F1,Ac2} = modify_anno1(F, Ac1, Mf),
-    {{named_fun,A1,N,F1,Id},Ac2};
-modify_anno1({attribute,A,N,[V]}, Ac, Mf) ->
-    {{attribute,A1,N1,V1},Ac1} = modify_anno1({attribute,A,N,V}, Ac, Mf),
-    {{attribute,A1,N1,[V1]},Ac1};
-%% End of sys_pre_expand special forms.
 modify_anno1({function,F,A}, Ac, _Mf) ->
     {{function,F,A},Ac};
 modify_anno1({function,M,F,A}, Ac, Mf) ->
diff --git a/lib/stdlib/src/qlc_pt.erl b/lib/stdlib/src/qlc_pt.erl
index 0db63b81f4..869b003668 100644
--- a/lib/stdlib/src/qlc_pt.erl
+++ b/lib/stdlib/src/qlc_pt.erl
@@ -1870,7 +1870,8 @@ prep_expr(E, F, S, BF, Imported) ->
 
 unify_column(Frame, Var, Col, BindFun, Imported) ->
     A = anno0(),
-    Call = {call,A,{atom,A,element},[{integer,A,Col}, {var,A,Var}]},
+    Call = {call,A,{remote,A,{atom,A,erlang},{atom,A,element}},
+	    [{integer,A,Col}, {var,A,Var}]},
     element_calls(Call, Frame, BindFun, Imported).
 
 %% cons_tuple is used for representing {V1, ..., Vi | TupleTail}.
@@ -1880,6 +1881,8 @@ unify_column(Frame, Var, Col, BindFun, Imported) ->
 %% about the size of the tuple is known.
 element_calls({call,_,{remote,_,{atom,_,erlang},{atom,_,element}},
                [{integer,_,I},Term0]}, F0, BF, Imported) when I > 0 ->
+    %% Note: erl_expand_records ensures that all calls to element/2
+    %% have an explicit "erlang:" prefix.
     TupleTail = unique_var(),
     VarsL = [unique_var() || _ <- lists:seq(1, I)],
     Vars = VarsL ++ TupleTail,
@@ -1887,10 +1890,6 @@ element_calls({call,_,{remote,_,{atom,_,erlang},{atom,_,element}},
     VarI = lists:nth(I, VarsL),
     {Term, F} = element_calls(Term0, F0, BF, Imported),
     {VarI, unify('=:=', Tuple, Term, F, BF, Imported)};
-element_calls({call,L1,{atom,_,element}=E,As}, F0, BF, Imported) ->
-    %% erl_expand_records should add "erlang:"...
-    element_calls({call,L1,{remote,L1,{atom,L1,erlang},E}, As}, F0, BF,
-                  Imported);
 element_calls(T, F0, BF, Imported) when is_tuple(T) ->
     {L, F} = element_calls(tuple_to_list(T), F0, BF, Imported),
     {list_to_tuple(L), F};