Merge branch 'hasse/unicode_atoms/OTP-14285'

* hasse/unicode_atoms/OTP-14285:
  compiler: Handle (bad) Unicode parse transform module names
  kernel: Improve handling of Unicode filenames
  stdlib: Handle Unicode atoms in ms_transform
  stdlib: Improve Unicode handling of the Erlang parser
  stdlib: Handle unknown compiler options with Unicode
  stdlib: Handle Unicode macro names
  stdlib: Correct Unicode handling in escript
  dialyzer: Improve handling of Unicode
  parsetools: Improve handling of Unicode atoms
  stdlib: Handle Unicode atoms when formatting stacktraces
  stdlib: Add more checks of module names to the linter
  stdlib: Handle Unicode atoms better in io_lib_format
  stdlib: Handle Unicode atoms in c.erl

11 files changed, 195 insertions, 167 deletions

diff --git a/lib/stdlib/src/c.erl b/lib/stdlib/src/c.erl
index bb7b485490..4ab9234b81 100644
--- a/lib/stdlib/src/c.erl
+++ b/lib/stdlib/src/c.erl
@@ -144,7 +144,7 @@ c(SrcFile, NewOpts, Filter, BeamFile, Info) ->
     F = fun (Opt) -> not is_outdir_opt(Opt) andalso Filter(Opt) end,
     Options = (NewOpts ++ [{outdir,filename:dirname(BeamFile)}]
                ++ lists:filter(F, old_options(Info))),
-    format("Recompiling ~s\n", [SrcFile]),
+    format("Recompiling ~ts\n", [SrcFile]),
     safe_recompile(SrcFile, Options, BeamFile).
 
 old_options(Info) ->
@@ -548,7 +548,7 @@ mfa_string(Fun) when is_function(Fun) ->
     {arity,A} = erlang:fun_info(Fun, arity),
     mfa_string({M,F,A});
 mfa_string({M,F,A}) ->
-    io_lib:format("~w:~w/~w", [M,F,A]);
+    io_lib:format("~w:~tw/~w", [M,F,A]);
 mfa_string(X) ->
     w(X).
 
@@ -572,7 +572,7 @@ display_info(Pid) ->
 		    w(Reds), w(LM)),
 	    iformat(case fetch(registered_name, Info) of
 			0 -> "";
-			X -> w(X)
+			X -> io_lib:format("~tw", [X])
 		    end,
 		    mfa_string(Curr),
 		    w(SS),
@@ -594,7 +594,7 @@ initial_call(Info)  ->
     end.
 
 iformat(A1, A2, A3, A4, A5) ->
-    format("~-21s ~-33s ~8s ~8s ~4s~n", [A1,A2,A3,A4,A5]).
+    format("~-21ts ~-33ts ~8s ~8s ~4s~n", [A1,A2,A3,A4,A5]).
 
 all_procs() ->
     case is_alive() of
@@ -767,7 +767,7 @@ print_exports(X) when length(X) > 16 ->
     split_print_exports(X);
 print_exports([]) -> ok;
 print_exports([{F, A} |Tail]) ->
-    format("         ~w/~w~n",[F, A]),
+    format("         ~tw/~w~n",[F, A]),
     print_exports(Tail).
 
 split_print_exports(L) ->
@@ -779,11 +779,11 @@ split_print_exports(L) ->
 
 split_print_exports([], [{F, A}|T]) ->
     Str = " ",
-    format("~-30s~w/~w~n", [Str, F, A]),
+    format("~-30ts~tw/~w~n", [Str, F, A]),
     split_print_exports([], T);
 split_print_exports([{F1, A1}|T1], [{F2, A2} | T2]) ->
-    Str = flatten(io_lib:format("~w/~w", [F1, A1])),
-    format("~-30s~w/~w~n", [Str, F2, A2]),
+    Str = flatten(io_lib:format("~tw/~w", [F1, A1])),
+    format("~-30ts~tw/~w~n", [Str, F2, A2]),
     split_print_exports(T1, T2);
 split_print_exports([], []) -> ok.
 
@@ -883,22 +883,22 @@ procline(Name, Info, Pid) ->
     Call = initial_call(Info),
     Reds  = fetch(reductions, Info),
     LM = length(fetch(messages, Info)),
-    procformat(io_lib:format("~w",[Name]),
+    procformat(io_lib:format("~tw",[Name]),
 	       io_lib:format("~w",[Pid]),
-	       io_lib:format("~s",[mfa_string(Call)]),
+	       io_lib:format("~ts",[mfa_string(Call)]),
 	       integer_to_list(Reds), integer_to_list(LM)).
 
 procformat(Name, Pid, Call, Reds, LM) ->
-    format("~-21s ~-12s ~-25s ~12s ~4s~n", [Name,Pid,Call,Reds,LM]).
+    format("~-21ts ~-12s ~-25ts ~12s ~4s~n", [Name,Pid,Call,Reds,LM]).
 
 portline(Name, Info, Id) ->
     Cmd = fetch(name, Info),
-    portformat(io_lib:format("~w",[Name]), 
+    portformat(io_lib:format("~tw",[Name]),
 	       erlang:port_to_list(Id),
 	       Cmd).
 
 portformat(Name, Id, Cmd) ->
-    format("~-21s ~-15s ~-40s~n", [Name,Id,Cmd]).
+    format("~-21ts ~-15s ~-40ts~n", [Name,Id,Cmd]).
 
 %% pwd()
 %% cd(Directory)
diff --git a/lib/stdlib/src/epp.erl b/lib/stdlib/src/epp.erl
index b35e9575a4..31d0d499e3 100644
--- a/lib/stdlib/src/epp.erl
+++ b/lib/stdlib/src/epp.erl
@@ -194,27 +194,27 @@ format_error(missing_parenthesis) ->
 format_error(premature_end) ->
     "premature end";
 format_error({call,What}) ->
-    io_lib:format("illegal macro call '~s'",[What]);
+    io_lib:format("illegal macro call '~ts'",[What]);
 format_error({undefined,M,none}) ->
-    io_lib:format("undefined macro '~s'", [M]);
+    io_lib:format("undefined macro '~ts'", [M]);
 format_error({undefined,M,A}) ->
-    io_lib:format("undefined macro '~s/~p'", [M,A]);
+    io_lib:format("undefined macro '~ts/~p'", [M,A]);
 format_error({depth,What}) ->
     io_lib:format("~s too deep",[What]);
 format_error({mismatch,M}) ->
-    io_lib:format("argument mismatch for macro '~s'", [M]);
+    io_lib:format("argument mismatch for macro '~ts'", [M]);
 format_error({arg_error,M}) ->
-    io_lib:format("badly formed argument for macro '~s'", [M]);
+    io_lib:format("badly formed argument for macro '~ts'", [M]);
 format_error({redefine,M}) ->
-    io_lib:format("redefining macro '~s'", [M]);
+    io_lib:format("redefining macro '~ts'", [M]);
 format_error({redefine_predef,M}) ->
     io_lib:format("redefining predefined macro '~s'", [M]);
 format_error({circular,M,none}) ->
-    io_lib:format("circular macro '~s'", [M]);
+    io_lib:format("circular macro '~ts'", [M]);
 format_error({circular,M,A}) ->
-    io_lib:format("circular macro '~s/~p'", [M,A]);
+    io_lib:format("circular macro '~ts/~p'", [M,A]);
 format_error({include,W,F}) ->
-    io_lib:format("can't find include ~s \"~s\"", [W,F]);
+    io_lib:format("can't find include ~s \"~ts\"", [W,F]);
 format_error({illegal,How,What}) ->
     io_lib:format("~s '-~s'", [How,What]);
 format_error({illegal_function,Macro}) ->
@@ -224,9 +224,9 @@ format_error({illegal_function_usage,Macro}) ->
 format_error({'NYI',What}) ->
     io_lib:format("not yet implemented '~s'", [What]);
 format_error({error,Term}) ->
-    io_lib:format("-error(~p).", [Term]);
+    io_lib:format("-error(~tp).", [Term]);
 format_error({warning,Term}) ->
-    io_lib:format("-warning(~p).", [Term]);
+    io_lib:format("-warning(~tp).", [Term]);
 format_error(E) -> file:format_error(E).
 
 -spec parse_file(FileName, IncludePath, PredefMacros) ->
@@ -1307,7 +1307,7 @@ expand_macros([{'?',_Lq},Token|_Toks], _St) ->
                 Text;
             undefined ->
                 Symbol = erl_scan:symbol(Token),
-                io_lib:write(Symbol)
+                io_lib:fwrite(<<"~tp">>, [Symbol])
         end,
     throw({error,loc(Token),{call,[$?|T]}});
 expand_macros([T|Ts], St) ->
diff --git a/lib/stdlib/src/erl_compile.erl b/lib/stdlib/src/erl_compile.erl
index 76db2eeacd..18d7548fdc 100644
--- a/lib/stdlib/src/erl_compile.erl
+++ b/lib/stdlib/src/erl_compile.erl
@@ -181,7 +181,7 @@ parse_generic_option("P", T, #options{specific=Spec}=Opts) ->
 parse_generic_option("S", T, #options{specific=Spec}=Opts) ->
     compile1(T, Opts#options{specific=['S'|Spec]});
 parse_generic_option(Option, _T, _Opts) ->
-    io:format(?STDERR, "Unknown option: -~s\n", [Option]),
+    io:format(?STDERR, "Unknown option: -~ts\n", [Option]),
     usage().
 
 parse_dep_option("", T) ->
@@ -202,7 +202,7 @@ parse_dep_option("T"++Opt, T0) ->
     {Target,T} = get_option("MT", Opt, T0),
     {[{makedep_target,Target}],T};
 parse_dep_option(Opt, _T) ->
-    io:format(?STDERR, "Unknown option: -M~s\n", [Opt]),
+    io:format(?STDERR, "Unknown option: -M~ts\n", [Opt]),
     usage().
 
 usage() ->
diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl
index d53a31db0d..fcfd0d8493 100644
--- a/lib/stdlib/src/erl_lint.erl
+++ b/lib/stdlib/src/erl_lint.erl
@@ -175,49 +175,50 @@ format_error(invalid_record) ->
     "invalid record expression";
 
 format_error({attribute,A}) ->
-    io_lib:format("attribute '~w' after function definitions", [A]);
+    io_lib:format("attribute ~tw after function definitions", [A]);
 format_error({missing_qlc_hrl,A}) ->
     io_lib:format("qlc:q/~w called, but \"qlc.hrl\" not included", [A]);
 format_error({redefine_import,{{F,A},M}}) ->
-    io_lib:format("function ~w/~w already imported from ~w", [F,A,M]);
+    io_lib:format("function ~tw/~w already imported from ~w", [F,A,M]);
 format_error({bad_inline,{F,A}}) ->
-    io_lib:format("inlined function ~w/~w undefined", [F,A]);
+    io_lib:format("inlined function ~tw/~w undefined", [F,A]);
 format_error({invalid_deprecated,D}) ->
-    io_lib:format("badly formed deprecated attribute ~w", [D]);
+    io_lib:format("badly formed deprecated attribute ~tw", [D]);
 format_error({bad_deprecated,{F,A}}) ->
-    io_lib:format("deprecated function ~w/~w undefined or not exported", [F,A]);
+    io_lib:format("deprecated function ~tw/~w undefined or not exported",
+                  [F,A]);
 format_error({bad_nowarn_unused_function,{F,A}}) ->
-    io_lib:format("function ~w/~w undefined", [F,A]);
+    io_lib:format("function ~tw/~w undefined", [F,A]);
 format_error({bad_nowarn_bif_clash,{F,A}}) ->
-    io_lib:format("function ~w/~w undefined", [F,A]);
+    io_lib:format("function ~tw/~w undefined", [F,A]);
 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]);
+    io_lib:format("~tw:~tw/~w is not a deprecated function", [M,F,A]);
 format_error({bad_on_load,Term}) ->
-    io_lib:format("badly formed on_load attribute: ~w", [Term]);
+    io_lib:format("badly formed on_load attribute: ~tw", [Term]);
 format_error(multiple_on_loads) ->
     "more than one on_load attribute";
 format_error({bad_on_load_arity,{F,A}}) ->
-    io_lib:format("function ~w/~w has wrong arity (must be 0)", [F,A]);
+    io_lib:format("function ~tw/~w has wrong arity (must be 0)", [F,A]);
 format_error({undefined_on_load,{F,A}}) ->
-    io_lib:format("function ~w/~w undefined", [F,A]);
+    io_lib:format("function ~tw/~w undefined", [F,A]);
 
 format_error(export_all) ->
     "export_all flag enabled - all functions will be exported";
 format_error({duplicated_export, {F,A}}) ->
-    io_lib:format("function ~w/~w already exported", [F,A]);
+    io_lib:format("function ~tw/~w already exported", [F,A]);
 format_error({unused_import,{{F,A},M}}) ->
-    io_lib:format("import ~w:~w/~w is unused", [M,F,A]);
+    io_lib:format("import ~w:~tw/~w is unused", [M,F,A]);
 format_error({undefined_function,{F,A}}) ->
-    io_lib:format("function ~w/~w undefined", [F,A]);
+    io_lib:format("function ~tw/~w undefined", [F,A]);
 format_error({redefine_function,{F,A}}) ->
-    io_lib:format("function ~w/~w already defined", [F,A]);
+    io_lib:format("function ~tw/~w already defined", [F,A]);
 format_error({define_import,{F,A}}) ->
-    io_lib:format("defining imported function ~w/~w", [F,A]);
+    io_lib:format("defining imported function ~tw/~w", [F,A]);
 format_error({unused_function,{F,A}}) ->
-    io_lib:format("function ~w/~w is unused", [F,A]);
+    io_lib:format("function ~tw/~w is unused", [F,A]);
 format_error({call_to_redefined_bif,{F,A}}) ->
     io_lib:format("ambiguous call of overridden auto-imported BIF ~w/~w~n"
 		  " - use erlang:~w/~w or \"-compile({no_auto_import,[~w/~w]}).\" "
@@ -273,7 +274,7 @@ 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",
+    io_lib:format("call to local/imported function ~tw/~w is illegal in guard",
 		  [F,A]);
 format_error(illegal_guard_expr) -> "illegal guard expression";
 %% --- maps ---
@@ -281,23 +282,23 @@ format_error(illegal_map_construction) ->
     "only association operators '=>' are allowed in map construction";
 %% --- records ---
 format_error({undefined_record,T}) ->
-    io_lib:format("record ~w undefined", [T]);
+    io_lib:format("record ~tw undefined", [T]);
 format_error({redefine_record,T}) ->
-    io_lib:format("record ~w already defined", [T]);
+    io_lib:format("record ~tw already defined", [T]);
 format_error({redefine_field,T,F}) ->
-    io_lib:format("field ~w already defined in record ~w", [F,T]);
+    io_lib:format("field ~tw already defined in record ~tw", [F,T]);
 format_error({undefined_field,T,F}) ->
-    io_lib:format("field ~w undefined in record ~w", [F,T]);
+    io_lib:format("field ~tw undefined in record ~tw", [F,T]);
 format_error(illegal_record_info) ->
     "illegal record info";
 format_error({field_name_is_variable,T,F}) ->
-    io_lib:format("field ~w is not an atom or _ in record ~w", [F,T]);
+    io_lib:format("field ~tw is not an atom or _ in record ~tw", [F,T]);
 format_error({wildcard_in_update,T}) ->
-    io_lib:format("meaningless use of _ in update of record ~w", [T]);
+    io_lib:format("meaningless use of _ in update of record ~tw", [T]);
 format_error({unused_record,T}) ->
-    io_lib:format("record ~w is unused", [T]);
+    io_lib:format("record ~tw is unused", [T]);
 format_error({untyped_record,T}) ->
-    io_lib:format("record ~w has field(s) without type information", [T]);
+    io_lib:format("record ~tw has field(s) without type information", [T]);
 %% --- variables ----
 format_error({unbound_var,V}) ->
     io_lib:format("variable ~w is unbound", [V]);
@@ -315,7 +316,7 @@ format_error({variable_in_record_def,V}) ->
     io_lib:format("variable ~w in record definition", [V]);
 %% --- binaries ---
 format_error({undefined_bittype,Type}) ->
-    io_lib:format("bit type ~w undefined", [Type]);
+    io_lib:format("bit type ~tw undefined", [Type]);
 format_error({bittype_mismatch,Val1,Val2,What}) ->
     io_lib:format("conflict in ~s specification for bit field: '~p' and '~p'",
 		  [What,Val1,Val2]);
@@ -335,13 +336,13 @@ format_error(unsized_binary_in_bin_gen_pattern) ->
     "binary fields without size are not allowed in patterns of bit string generators";
 %% --- behaviours ---
 format_error({conflicting_behaviours,{Name,Arity},B,FirstL,FirstB}) ->
-    io_lib:format("conflicting behaviours - callback ~w/~w required by both '~p' "
+    io_lib:format("conflicting behaviours - callback ~tw/~w required by both '~p' "
 		  "and '~p' ~s", [Name,Arity,B,FirstB,format_where(FirstL)]);
 format_error({undefined_behaviour_func, {Func,Arity}, Behaviour}) ->
-    io_lib:format("undefined callback function ~w/~w (behaviour '~w')",
+    io_lib:format("undefined callback function ~tw/~w (behaviour '~w')",
 		  [Func,Arity,Behaviour]);
 format_error({undefined_behaviour,Behaviour}) ->
-    io_lib:format("behaviour ~w undefined", [Behaviour]);
+    io_lib:format("behaviour ~tw undefined", [Behaviour]);
 format_error({undefined_behaviour_callbacks,Behaviour}) ->
     io_lib:format("behaviour ~w callback functions are undefined",
 		  [Behaviour]);
@@ -352,23 +353,23 @@ format_error({ill_defined_optional_callbacks,Behaviour}) ->
     io_lib:format("behaviour ~w optional callback functions erroneously defined",
 		  [Behaviour]);
 format_error({behaviour_info, {_M,F,A}}) ->
-    io_lib:format("cannot define callback attibute for ~w/~w when "
+    io_lib:format("cannot define callback attibute for ~tw/~w when "
                   "behaviour_info is defined",[F,A]);
 format_error({redefine_optional_callback, {F, A}}) ->
-    io_lib:format("optional callback ~w/~w duplicated", [F, A]);
+    io_lib:format("optional callback ~tw/~w duplicated", [F, A]);
 format_error({undefined_callback, {_M, F, A}}) ->
-    io_lib:format("callback ~w/~w is undefined", [F, A]);
+    io_lib:format("callback ~tw/~w is undefined", [F, A]);
 %% --- types and specs ---
 format_error({singleton_typevar, Name}) ->
     io_lib:format("type variable ~w is only used once (is unbound)", [Name]);
 format_error({bad_export_type, _ETs}) ->
     io_lib:format("bad export_type declaration", []);
 format_error({duplicated_export_type, {T, A}}) ->
-    io_lib:format("type ~w/~w already exported", [T, A]);
+    io_lib:format("type ~tw/~w already exported", [T, A]);
 format_error({undefined_type, {TypeName, Arity}}) ->
-    io_lib:format("type ~w~s undefined", [TypeName, gen_type_paren(Arity)]);
+    io_lib:format("type ~tw~s undefined", [TypeName, gen_type_paren(Arity)]);
 format_error({unused_type, {TypeName, Arity}}) ->
-    io_lib:format("type ~w~s is unused", [TypeName, gen_type_paren(Arity)]);
+    io_lib:format("type ~tw~s is unused", [TypeName, gen_type_paren(Arity)]);
 format_error({new_builtin_type, {TypeName, Arity}}) ->
     io_lib:format("type ~w~s is a new builtin type; "
 		  "its (re)definition is allowed only until the next release",
@@ -380,25 +381,26 @@ format_error({renamed_type, OldName, NewName}) ->
     io_lib:format("type ~w() is now called ~w(); "
 		  "please use the new name instead", [OldName, NewName]);
 format_error({redefine_type, {TypeName, Arity}}) ->
-    io_lib:format("type ~w~s already defined",
+    io_lib:format("type ~tw~s already defined",
 		  [TypeName, gen_type_paren(Arity)]);
 format_error({type_syntax, Constr}) ->
-    io_lib:format("bad ~w type", [Constr]);
+    io_lib:format("bad ~tw type", [Constr]);
 format_error(old_abstract_code) ->
     io_lib:format("abstract code generated before Erlang/OTP 19.0 and "
                   "having typed record fields cannot be compiled", []);
 format_error({redefine_spec, {M, F, A}}) ->
-    io_lib:format("spec for ~w:~w/~w already defined", [M, F, A]);
+    io_lib:format("spec for ~tw:~tw/~w already defined", [M, F, A]);
 format_error({redefine_spec, {F, A}}) ->
-    io_lib:format("spec for ~w/~w already defined", [F, A]);
+    io_lib:format("spec for ~tw/~w already defined", [F, A]);
 format_error({redefine_callback, {F, A}}) ->
-    io_lib:format("callback ~w/~w already defined", [F, A]);
+    io_lib:format("callback ~tw/~w already defined", [F, A]);
 format_error({bad_callback, {M, F, A}}) ->
-    io_lib:format("explicit module not allowed for callback ~w:~w/~w ", [M, F, A]);
+    io_lib:format("explicit module not allowed for callback ~tw:~tw/~w",
+                  [M, F, A]);
 format_error({spec_fun_undefined, {F, A}}) ->
-    io_lib:format("spec for undefined function ~w/~w", [F, A]);
+    io_lib:format("spec for undefined function ~tw/~w", [F, A]);
 format_error({missing_spec, {F,A}}) ->
-    io_lib:format("missing specification for function ~w/~w", [F, A]);
+    io_lib:format("missing specification for function ~tw/~w", [F, A]);
 format_error(spec_wrong_arity) ->
     "spec has wrong arity";
 format_error(callback_wrong_arity) ->
@@ -417,15 +419,15 @@ format_error({deprecated_builtin_type, {Name, Arity},
                   "removed in ~s; use ~s",
                   [Name, Arity, Rel, UseS]);
 format_error({not_exported_opaque, {TypeName, Arity}}) ->
-    io_lib:format("opaque type ~w~s is not exported",
+    io_lib:format("opaque type ~tw~s is not exported",
                   [TypeName, gen_type_paren(Arity)]);
 format_error({underspecified_opaque, {TypeName, Arity}}) ->
-    io_lib:format("opaque type ~w~s is underspecified and therefore meaningless",
+    io_lib:format("opaque type ~tw~s is underspecified and therefore meaningless",
                   [TypeName, gen_type_paren(Arity)]);
 format_error({bad_dialyzer_attribute,Term}) ->
-    io_lib:format("badly formed dialyzer attribute: ~w", [Term]);
+    io_lib:format("badly formed dialyzer attribute: ~tw", [Term]);
 format_error({bad_dialyzer_option,Term}) ->
-    io_lib:format("unknown dialyzer warning option: ~w", [Term]);
+    io_lib:format("unknown dialyzer warning option: ~tw", [Term]);
 %% --- obsolete? unused? ---
 format_error({format_error, {Fmt, Args}}) ->
     io_lib:format(Fmt, Args).
@@ -763,12 +765,7 @@ start_state({attribute,Line,module,{_,_}}=Form, St0) ->
 start_state({attribute,Line,module,M}, St0) ->
     St1 = St0#lint{module=M},
     St2 = St1#lint{state=attribute},
-    case is_non_latin1_name(M) of
-        true ->
-            add_error(Line, non_latin1_module_unsupported, St2);
-        false ->
-            St2
-    end;
+    check_module_name(M, Line, St2);
 start_state(Form, St) ->
     Anno = case Form of
                {eof, L} -> erl_anno:new(L);
@@ -778,9 +775,6 @@ start_state(Form, St) ->
     St1 = add_error(Anno, undefined_module, St),
     attribute_state(Form, St1#lint{state=attribute}).
 
-is_non_latin1_name(Name) ->
-    lists:any(fun(C) -> C > 255 end, atom_to_list(Name)).
-
 %% attribute_state(Form, State) ->
 %%      State'
 
@@ -865,7 +859,11 @@ not_deprecated(Forms, St0) ->
     Bad = [MFAL || {{M,F,A},_L}=MFAL <- MFAsL,
                    otp_internal:obsolete(M, F, A) =:= no],
     St1 = func_line_warning(bad_nowarn_deprecated_function, Bad, St0),
-    St1#lint{not_deprecated = ordsets:from_list(Nowarn)}.
+    ML = [{M,L} || {{M,_F,_A},L} <- MFAsL, is_atom(M)],
+    St3 = foldl(fun ({M,L}, St2) ->
+                        check_module_name(M, L, St2)
+                end, St1, ML),
+    St3#lint{not_deprecated = ordsets:from_list(Nowarn)}.
 
 %% The nowarn_bif_clash directive is not only deprecated, it's actually an error from R14A
 disallowed_compile_flags(Forms, St0) ->
@@ -972,7 +970,8 @@ behaviour_callbacks(Line, B, St0) ->
     catch
         _:_ ->
             St1 = add_warning(Line, {undefined_behaviour, B}, St0),
-            {[], [], St1}
+            St2 = check_module_name(B, Line, St1),
+            {[], [], St2}
     end.
 
 behaviour_missing_callbacks([{{Line,B},Bfs0,OBfs}|T], St0) ->
@@ -1310,7 +1309,8 @@ exports(#lint{compile = Opts, defined = Defs, exports = Es}) ->
 -type import() :: {module(), [fa()]} | module().
 -spec import(line(), import(), lint_state()) -> lint_state().
 
-import(Line, {Mod,Fs}, St) ->
+import(Line, {Mod,Fs}, St00) ->
+    St = check_module_name(Mod, Line, St00),
     Mfs = ordsets:from_list(Fs),
     case check_imports(Line, Mfs, St#lint.imports) of
 	[] ->
@@ -2294,11 +2294,18 @@ expr({call,L,{tuple,Lt,[{atom,Lm,erlang},{atom,Lf,is_record}]},As}, Vt, St) ->
 expr({call,Line,{remote,_Lr,{atom,_Lm,M},{atom,Lf,F}},As}, Vt, St0) ->
     St1 = keyword_warning(Lf, F, St0),
     St2 = check_remote_function(Line, M, F, As, St1),
-    expr_list(As, Vt, St2);
+    St3 = check_module_name(M, Line, St2),
+    expr_list(As, Vt, St3);
 expr({call,Line,{remote,_Lr,M,F},As}, Vt, St0) ->
     St1 = keyword_warning(Line, M, St0),
     St2 = keyword_warning(Line, F, St1),
-    expr_list([M,F|As], Vt, St2);
+    St3 = case M of
+              {atom,Lm,Mod} ->
+                  check_module_name(Mod, Lm, St2);
+              _ ->
+                  St2
+          end,
+    expr_list([M,F|As], Vt, St3);
 expr({call,Line,{atom,La,F},As}, Vt, St0) ->
     St1 = keyword_warning(La, F, St0),
     {Asvt,St2} = expr_list(As, Vt, St1),
@@ -2814,7 +2821,8 @@ check_type(Types, St) ->
 check_type({ann_type, _L, [_Var, Type]}, SeenVars, St) ->
     check_type(Type, SeenVars, St);
 check_type({remote_type, L, [{atom, _, Mod}, {atom, _, Name}, Args]},
-	   SeenVars, St0) ->
+	   SeenVars, St00) ->
+    St0 = check_module_name(Mod, L, St00),
     St = deprecated_type(L, Mod, Name, Args, St0),
     CurrentMod = St#lint.module,
     case Mod =:= CurrentMod of
@@ -2973,11 +2981,12 @@ obsolete_builtin_type({Name, A}) when is_atom(Name), is_integer(A) -> no.
 
 %% spec_decl(Line, Fun, Types, State) -> State.
 
-spec_decl(Line, MFA0, TypeSpecs, St0 = #lint{specs = Specs, module = Mod}) ->
+spec_decl(Line, MFA0, TypeSpecs, St00 = #lint{specs = Specs, module = Mod}) ->
     MFA = case MFA0 of
 	      {F, Arity} -> {Mod, F, Arity};
 	      {_M, _F, Arity} -> MFA0
 	  end,
+    St0 = check_module_name(element(1, MFA), Line, St00),
     St1 = St0#lint{specs = dict:store(MFA, Line, Specs)},
     case dict:is_key(MFA, Specs) of
 	true -> add_error(Line, {redefine_spec, MFA0}, St1);
@@ -2989,7 +2998,9 @@ spec_decl(Line, MFA0, TypeSpecs, St0 = #lint{specs = Specs, module = Mod}) ->
 callback_decl(Line, MFA0, TypeSpecs,
 	      St0 = #lint{callbacks = Callbacks, module = Mod}) ->
     case MFA0 of
-        {_M, _F, _A} -> add_error(Line, {bad_callback, MFA0}, St0);
+        {M, _F, _A} ->
+            St1 = check_module_name(M, Line, St0),
+            add_error(Line, {bad_callback, MFA0}, St1);
         {F, Arity} ->
             MFA = {Mod, F, Arity},
             St1 = St0#lint{callbacks = dict:store(MFA, Line, Callbacks)},
@@ -3033,6 +3044,16 @@ is_fa({FuncName, Arity})
   when is_atom(FuncName), is_integer(Arity), Arity >= 0 -> true;
 is_fa(_) -> false.
 
+check_module_name(M, Line, St) ->
+    case is_latin1_name(M) of
+        true -> St;
+        false ->
+            add_error(Line, non_latin1_module_unsupported, St)
+    end.
+
+is_latin1_name(Name) ->
+    io_lib:latin1_char_list(atom_to_list(Name)).
+
 check_specs([FunType|Left], ETag, Arity, St0) ->
     {FunType1, CTypes} =
 	case FunType of
diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl
index 733932e711..6e72d64acc 100644
--- a/lib/stdlib/src/erl_parse.yrl
+++ b/lib/stdlib/src/erl_parse.yrl
@@ -1097,12 +1097,12 @@ build_compat_constraint({atom, _, is_subtype}, [{var, _, _}=LHS, Type]) ->
 build_compat_constraint({atom, _, is_subtype}, [LHS, _Type]) ->
     ret_err(?anno(LHS), "bad type variable");
 build_compat_constraint({atom, A, Atom}, _Types) ->
-    ret_err(A, io_lib:format("unsupported constraint ~w", [Atom])).
+    ret_err(A, io_lib:format("unsupported constraint ~tw", [Atom])).
 
 build_constraint({atom, _, is_subtype}, [{var, _, _}=LHS, Type]) ->
     build_constraint(LHS, Type);
 build_constraint({atom, A, Atom}, _Foo) ->
-    ret_err(A, io_lib:format("unsupported constraint ~w", [Atom]));
+    ret_err(A, io_lib:format("unsupported constraint ~tw", [Atom]));
 build_constraint({var, A, '_'}, _Types) ->
     ret_err(A, "bad type variable");
 build_constraint(LHS, Type) ->
@@ -1220,7 +1220,7 @@ attribute_farity_map(Args) ->
 -spec error_bad_decl(erl_anno:anno(), attributes()) -> no_return().
 
 error_bad_decl(Anno, S) ->
-    ret_err(Anno, io_lib:format("bad ~w declaration", [S])).
+    ret_err(Anno, io_lib:format("bad ~tw declaration", [S])).
 
 farity_list({cons,_Ac,{op,_Ao,'/',{atom,_Aa,A},{integer,_Ai,I}},Tail}) ->
     [{A,I}|farity_list(Tail)];
diff --git a/lib/stdlib/src/escript.erl b/lib/stdlib/src/escript.erl
index f2629a47c2..2093916a7c 100644
--- a/lib/stdlib/src/escript.erl
+++ b/lib/stdlib/src/escript.erl
@@ -281,12 +281,12 @@ start(EscriptOptions) ->
         end
     catch
         throw:Str ->
-            io:format("escript: ~s\n", [Str]),
+            io:format("escript: ~ts\n", [Str]),
             my_halt(127);
         _:Reason ->
             Stk = erlang:get_stacktrace(),
-            io:format("escript: Internal error: ~p\n", [Reason]),
-            io:format("~p\n", [Stk]),
+            io:format("escript: Internal error: ~tp\n", [Reason]),
+            io:format("~tp\n", [Stk]),
             my_halt(127)
     end.
 
diff --git a/lib/stdlib/src/io_lib_format.erl b/lib/stdlib/src/io_lib_format.erl
index 14d925bacf..4b2d15c8b3 100644
--- a/lib/stdlib/src/io_lib_format.erl
+++ b/lib/stdlib/src/io_lib_format.erl
@@ -335,7 +335,7 @@ base(B) when is_integer(B) ->
 term(T, none, _Adj, none, _Pad) -> T;
 term(T, none, Adj, P, Pad) -> term(T, P, Adj, P, Pad);
 term(T, F, Adj, P0, Pad) ->
-    L = lists:flatlength(T),
+    L = string:length(T),
     P = erlang:min(L, case P0 of none -> F; _ -> min(P0, F) end),
     if
 	L > P ->
@@ -675,11 +675,11 @@ cdata_to_chars(B) when is_binary(B) ->
 
 string(S, none, _Adj, none, _Pad) -> S;
 string(S, F, Adj, none, Pad) ->
-    string_field(S, F, Adj, lists:flatlength(S), Pad);
+    string_field(S, F, Adj, string:length(S), Pad);
 string(S, none, _Adj, P, Pad) ->
-    string_field(S, P, left, lists:flatlength(S), Pad);
+    string_field(S, P, left, string:length(S), Pad);
 string(S, F, Adj, P, Pad) when F >= P ->
-    N = lists:flatlength(S),
+    N = string:length(S),
     if F > P ->
 	    if N > P ->
 		    adjust(flat_trunc(S, P), chars(Pad, F-P), Adj);
@@ -749,18 +749,7 @@ adjust(Data, Pad, right) -> [Pad|Data].
 %% Flatten and truncate a deep list to at most N elements.
 
 flat_trunc(List, N) when is_integer(N), N >= 0 ->
-    flat_trunc(List, N, [], []).
-
-flat_trunc(L, 0, _, R) when is_list(L) ->
-    lists:reverse(R);
-flat_trunc([H|T], N, S, R) when is_list(H) ->
-    flat_trunc(H, N, [T|S], R);
-flat_trunc([H|T], N, S, R) ->
-    flat_trunc(T, N-1, S, [H|R]);
-flat_trunc([], N, [H|S], R) ->
-    flat_trunc(H, N, S, R);
-flat_trunc([], _, [], R) ->
-    lists:reverse(R).
+    string:slice(List, 0, N).
 
 %% A deep version of string:chars/2,3
 
diff --git a/lib/stdlib/src/io_lib_pretty.erl b/lib/stdlib/src/io_lib_pretty.erl
index ff368d02da..505613b80e 100644
--- a/lib/stdlib/src/io_lib_pretty.erl
+++ b/lib/stdlib/src/io_lib_pretty.erl
@@ -473,7 +473,7 @@ print_length(<<_/bitstring>>=Bin, D, _RF, Enc, Str) ->
 print_length(Term, _D, _RF, _Enc, _Str) ->
     S = io_lib:write(Term),
     %% S can contain unicode, so iolist_size(S) cannot be used here
-    {S, lists:flatlength(S)}.
+    {S, string:length(S)}.
 
 print_length_map(_Map, 1, _RF, _Enc, _Str) ->
     {"#{...}", 6};
diff --git a/lib/stdlib/src/lib.erl b/lib/stdlib/src/lib.erl
index aa6797bce6..c6eb0d7915 100644
--- a/lib/stdlib/src/lib.erl
+++ b/lib/stdlib/src/lib.erl
@@ -27,7 +27,7 @@
 
 -export([format_exception/6, format_exception/7,
          format_stacktrace/4, format_stacktrace/5,
-         format_call/4, format_call/5, format_fun/1]).
+         format_call/4, format_call/5, format_fun/1, format_fun/2]).
 
 -spec flush_receive() -> 'ok'.
 
@@ -400,7 +400,11 @@ format_call(I, ForMForFun, As, FormatFun, Enc)
     format_call("", n_spaces(I-1), ForMForFun, As, FormatFun, Enc).
 
 %% -> iolist() (no \n at end)
-format_fun(Fun) when is_function(Fun) ->
+format_fun(Fun) ->
+    format_fun(Fun, latin1).
+
+%% -> iolist() (no \n at end)
+format_fun(Fun, Enc) when is_function(Fun) ->
     {module, M} = erlang:fun_info(Fun, module),
     {name, F} = erlang:fun_info(Fun, name),
     {arity, A} = erlang:fun_info(Fun, arity),
@@ -410,9 +414,9 @@ format_fun(Fun) when is_function(Fun) ->
         {type, local} when M =:= erl_eval ->
             io_lib:fwrite(<<"interpreted function with arity ~w">>, [A]);
         {type, local} ->
-            mfa_to_string(M, F, A);
+            mfa_to_string(M, F, A, Enc);
         {type, external} ->
-            mfa_to_string(M, F, A)
+            mfa_to_string(M, F, A, Enc)
     end.
 
 analyze_exception(error, Term, Stack) ->
@@ -454,11 +458,11 @@ explain_reason({badarg,V}, error=Cl, [], PF, S, _Enc) -> % orelse, andalso
     format_value(V, <<"bad argument: ">>, Cl, PF, S);
 explain_reason(badarith, error, [], _PF, _S, _Enc) ->
     <<"an error occurred when evaluating an arithmetic expression">>;
-explain_reason({badarity,{Fun,As}}, error, [], _PF, _S, _Enc)
+explain_reason({badarity,{Fun,As}}, error, [], _PF, _S, Enc)
                                       when is_function(Fun) ->
     %% Only the arity is displayed, not the arguments As.
-    io_lib:fwrite(<<"~s called with ~s">>, 
-                  [format_fun(Fun), argss(length(As))]);
+    io_lib:fwrite(<<"~ts called with ~s">>,
+                  [format_fun(Fun, Enc), argss(length(As))]);
 explain_reason({badfun,Term}, error=Cl, [], PF, S, _Enc) ->
     format_value(Term, <<"bad function ">>, Cl, PF, S);
 explain_reason({badmatch,Term}, error=Cl, [], PF, S, _Enc) ->
@@ -489,14 +493,15 @@ explain_reason({try_clause,V}, error=Cl, [], PF, S, _Enc) ->
     %% "there is no try clause with a true guard sequence and a
     %% pattern matching..."
     format_value(V, <<"no try clause matching ">>, Cl, PF, S);
-explain_reason(undef, error, [{M,F,A,_}], _PF, _S, _Enc) ->
+explain_reason(undef, error, [{M,F,A,_}], _PF, _S, Enc) ->
     %% Only the arity is displayed, not the arguments, if there are any.
-    io_lib:fwrite(<<"undefined function ~s">>, 
-                  [mfa_to_string(M, F, n_args(A))]);
-explain_reason({shell_undef,F,A,_}, error, [], _PF, _S, _Enc) ->
+    io_lib:fwrite(<<"undefined function ~ts">>,
+                  [mfa_to_string(M, F, n_args(A), Enc)]);
+explain_reason({shell_undef,F,A,_}, error, [], _PF, _S, Enc) ->
     %% Give nicer reports for undefined shell functions
     %% (but not when the user actively calls shell_default:F(...)).
-    io_lib:fwrite(<<"undefined shell command ~s/~w">>, [F, n_args(A)]);
+    FS = to_string(F, Enc),
+    io_lib:fwrite(<<"undefined shell command ~ts/~w">>, [FS, n_args(A)]);
 %% Exit codes returned by erl_eval only:
 explain_reason({argument_limit,_Fun}, error, [], _PF, _S, _Enc) ->
     io_lib:fwrite(<<"limit of number of arguments to interpreted function"
@@ -546,17 +551,18 @@ format_stacktrace1(S0, Stack0, PF, SF, Enc) ->
     format_stacktrace2(S, Stack, 1, PF, Enc).
 
 format_stacktrace2(S, [{M,F,A,L}|Fs], N, PF, Enc) when is_integer(A) ->
-    [io_lib:fwrite(<<"~s~s ~s ~s">>,
+    [io_lib:fwrite(<<"~s~s ~ts ~s">>,
                    [sep(N, S), origin(N, M, F, A),
-		    mfa_to_string(M, F, A),
+		    mfa_to_string(M, F, A, Enc),
 		    location(L)])
      | format_stacktrace2(S, Fs, N + 1, PF, Enc)];
 format_stacktrace2(S, [{M,F,As,_}|Fs], N, PF, Enc) when is_list(As) ->
     A = length(As),
     CalledAs = [S,<<"   called as ">>],
     C = format_call("", CalledAs, {M,F}, As, PF, Enc),
-    [io_lib:fwrite(<<"~s~s ~s\n~s~ts">>,
-		   [sep(N, S), origin(N, M, F, A), mfa_to_string(M, F, A),
+    [io_lib:fwrite(<<"~s~s ~ts\n~s~ts">>,
+		   [sep(N, S), origin(N, M, F, A),
+                    mfa_to_string(M, F, A, Enc),
                     CalledAs, C])
      | format_stacktrace2(S, Fs, N + 1, PF, Enc)];
 format_stacktrace2(_S, [], _N, _PF, _Enc) ->
@@ -594,10 +600,10 @@ format_call(ErrStr, Pre1, ForMForFun, As, PF, Enc) ->
          {yes,Op} -> 
              format_op(ErrStr, Pre1, Op, As, PF, Enc);
          no ->
-             MFs = mf_to_string(ForMForFun, Arity),
-             I1 = iolist_size([Pre1,ErrStr|MFs]),
+             MFs = mf_to_string(ForMForFun, Arity, Enc),
+             I1 = string:length([Pre1,ErrStr|MFs]),
              S1 = pp_arguments(PF, As, I1, Enc),
-             S2 = pp_arguments(PF, As, iolist_size([Pre1|MFs]), Enc),
+             S2 = pp_arguments(PF, As, string:length([Pre1|MFs]), Enc),
              Long = count_nl(pp_arguments(PF, [a2345,b2345], I1, Enc)) > 0,
              case Long or (count_nl(S2) < count_nl(S1)) of
                  true ->
@@ -656,10 +662,10 @@ printable_list(latin1, As) ->
 printable_list(_, As) ->
     io_lib:printable_list(As).
 
-mfa_to_string(M, F, A) ->
-    io_lib:fwrite(<<"~s/~w">>, [mf_to_string({M, F}, A), A]).
+mfa_to_string(M, F, A, Enc) ->
+    io_lib:fwrite(<<"~ts/~w">>, [mf_to_string({M, F}, A, Enc), A]).
 
-mf_to_string({M, F}, A) ->
+mf_to_string({M, F}, A, Enc) ->
     case erl_internal:bif(M, F, A) of
         true ->
             io_lib:fwrite(<<"~w">>, [F]);
@@ -670,13 +676,15 @@ mf_to_string({M, F}, A) ->
                 {yes, F} ->
                     atom_to_list(F);
                 no ->
-                    io_lib:fwrite(<<"~w:~w">>, [M, F])
+                    FS = to_string(F, Enc),
+                    io_lib:fwrite(<<"~w:~ts">>, [M, FS])
             end
     end;
-mf_to_string(Fun, _A) when is_function(Fun) ->
-    format_fun(Fun);
-mf_to_string(F, _A) ->
-    io_lib:fwrite(<<"~w">>, [F]).
+mf_to_string(Fun, _A, Enc) when is_function(Fun) ->
+    format_fun(Fun, Enc);
+mf_to_string(F, _A, Enc) ->
+    FS = to_string(F, Enc),
+    io_lib:fwrite(<<"~ts">>, [FS]).
 
 format_value(V, ErrStr, Class, PF, S) ->
     Pre1Sz = exited_size(Class),
@@ -725,9 +733,14 @@ exited(exit) ->
 exited(throw) ->
     <<"exception throw: ">>.
 
+to_string(A, latin1) ->
+    io_lib:write_atom_as_latin1(A);
+to_string(A, _) ->
+    io_lib:write_atom(A).
+
 size(latin1, S) ->
     {iolist_size(S),S};
 size(_, S0) ->
     S = unicode:characters_to_list(S0, unicode),
     true = is_list(S),
-    {length(S),S}.
+    {string:length(S),S}.
diff --git a/lib/stdlib/src/ms_transform.erl b/lib/stdlib/src/ms_transform.erl
index 98745b13f3..c1c09f091c 100644
--- a/lib/stdlib/src/ms_transform.erl
+++ b/lib/stdlib/src/ms_transform.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %% 
-%% Copyright Ericsson AB 2002-2016. All Rights Reserved.
+%% Copyright Ericsson AB 2002-2017. All Rights Reserved.
 %% 
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -91,12 +91,12 @@ format_error(?ERR_GUARDMATCH) ->
     "fun with guard matching ('=' in guard) is illegal as match_spec as well";
 format_error({?ERR_GUARDLOCALCALL, Name, Arithy}) ->	    
     lists:flatten(io_lib:format("fun containing the local function call "
-				"'~w/~w' (called in guard) "
+				"'~tw/~w' (called in guard) "
 				"cannot be translated into match_spec",
 				[Name, Arithy]));
 format_error({?ERR_GUARDREMOTECALL, Module, Name, Arithy}) ->	    
     lists:flatten(io_lib:format("fun containing the remote function call "
-				"'~w:~w/~w' (called in guard) "
+				"'~w:~tw/~w' (called in guard) "
 				"cannot be translated into match_spec",
 				[Module,Name,Arithy]));
 format_error({?ERR_GUARDELEMENT, Str}) ->
@@ -117,12 +117,12 @@ format_error(?ERR_BODYMATCH) ->
     "fun with body matching ('=' in body) is illegal as match_spec";
 format_error({?ERR_BODYLOCALCALL, Name, Arithy}) ->	    
     lists:flatten(io_lib:format("fun containing the local function "
-				"call '~w/~w' (called in body) "
+				"call '~tw/~w' (called in body) "
 				"cannot be translated into match_spec",
 				[Name,Arithy]));
 format_error({?ERR_BODYREMOTECALL, Module, Name, Arithy}) ->	    
     lists:flatten(io_lib:format("fun containing the remote function call "
-				"'~w:~w/~w' (called in body) "
+				"'~w:~tw/~w' (called in body) "
 				"cannot be translated into match_spec",
 				[Module,Name,Arithy]));
 format_error({?ERR_BODYELEMENT, Str}) ->
@@ -147,15 +147,15 @@ format_error({?ERR_UNBOUND_VARIABLE, Str}) ->
 		    "into match_spec", [Str]));
 format_error({?ERR_HEADBADREC,Name}) ->	    
     lists:flatten(
-      io_lib:format("fun head contains unknown record type ~w",[Name]));
+      io_lib:format("fun head contains unknown record type ~tw",[Name]));
 format_error({?ERR_HEADBADFIELD,RName,FName}) ->	    
     lists:flatten(
-      io_lib:format("fun head contains reference to unknown field ~w in "
-		    "record type ~w",[FName, RName]));
+      io_lib:format("fun head contains reference to unknown field ~tw in "
+		    "record type ~tw",[FName, RName]));
 format_error({?ERR_HEADMULTIFIELD,RName,FName}) ->	    
     lists:flatten(
-      io_lib:format("fun head contains already defined field ~w in "
-		    "record type ~w",[FName, RName]));
+      io_lib:format("fun head contains already defined field ~tw in "
+		    "record type ~tw",[FName, RName]));
 format_error({?ERR_HEADDOLLARATOM,Atom}) ->	    
     lists:flatten(
       io_lib:format("fun head contains atom ~w, which conflics with reserved "
@@ -166,28 +166,28 @@ format_error({?ERR_HEADBINMATCH,Atom}) ->
 		    "which cannot be translated into match_spec", [Atom]));
 format_error({?ERR_GUARDBADREC,Name}) ->	    
     lists:flatten(
-      io_lib:format("fun guard contains unknown record type ~w",[Name]));
+      io_lib:format("fun guard contains unknown record type ~tw",[Name]));
 format_error({?ERR_GUARDBADFIELD,RName,FName}) ->	    
     lists:flatten(
-      io_lib:format("fun guard contains reference to unknown field ~w in "
-		    "record type ~w",[FName, RName]));
+      io_lib:format("fun guard contains reference to unknown field ~tw in "
+		    "record type ~tw",[FName, RName]));
 format_error({?ERR_GUARDMULTIFIELD,RName,FName}) ->	    
     lists:flatten(
-      io_lib:format("fun guard contains already defined field ~w in "
-		    "record type ~w",[FName, RName]));
+      io_lib:format("fun guard contains already defined field ~tw in "
+		    "record type ~tw",[FName, RName]));
 format_error({?ERR_BODYBADREC,Name}) ->	    
     lists:flatten(
-      io_lib:format("fun body contains unknown record type ~w",[Name]));
+      io_lib:format("fun body contains unknown record type ~tw",[Name]));
 format_error({?ERR_BODYBADFIELD,RName,FName}) ->	    
     lists:flatten(
-      io_lib:format("fun body contains reference to unknown field ~w in "
-		    "record type ~w",[FName, RName]));
+      io_lib:format("fun body contains reference to unknown field ~tw in "
+		    "record type ~tw",[FName, RName]));
 format_error({?ERR_BODYMULTIFIELD,RName,FName}) ->	    
     lists:flatten(
-      io_lib:format("fun body contains already defined field ~w in "
-		    "record type ~w",[FName, RName]));
+      io_lib:format("fun body contains already defined field ~tw in "
+		    "record type ~tw",[FName, RName]));
 format_error(Else) ->
-    lists:flatten(io_lib:format("Unknown error code ~w",[Else])).
+    lists:flatten(io_lib:format("Unknown error code ~tw",[Else])).
 
 %%
 %% Called when translating in shell
@@ -723,7 +723,7 @@ tg(T,B) when is_tuple(T), tuple_size(T) >= 2 ->
     throw({error,Line,{?ERR_GENELEMENT+B#tgd.eb,
 		       translate_language_element(Element)}}); 
 tg(Other,B) ->
-    Element = io_lib:format("unknown element ~w", [Other]),
+    Element = io_lib:format("unknown element ~tw", [Other]),
     throw({error,unknown,{?ERR_GENELEMENT+B#tgd.eb,Element}}).
 
 transform_head([V],OuterBound) ->
diff --git a/lib/stdlib/src/proc_lib.erl b/lib/stdlib/src/proc_lib.erl
index 3fa54cd0d5..9ce8e7d60e 100644
--- a/lib/stdlib/src/proc_lib.erl
+++ b/lib/stdlib/src/proc_lib.erl
@@ -805,16 +805,21 @@ format_exception(Class, Reason, StackTrace, {Enc,_}=Extra) ->
     [EI, lib:format_exception(1+length(EI), Class, Reason, 
                               StackTrace, StackFun, PF, Enc), "\n"].
 
-format_mfa(Indent, {M,F,Args}=StartF, Extra) ->
+format_mfa(Indent, {M,F,Args}=StartF, {Enc,_}=Extra) ->
     try
 	A = length(Args),
-	[Indent,"initial call: ",atom_to_list(M),$:,atom_to_list(F),$/,
+	[Indent,"initial call: ",atom_to_list(M),$:,to_string(F, Enc),$/,
 	 integer_to_list(A),"\n"]
     catch
 	error:_ ->
 	    format_tag(Indent, initial_call, StartF, Extra)
     end.
 
+to_string(A, latin1) ->
+    io_lib:write_atom_as_latin1(A);
+to_string(A, _) ->
+    io_lib:write_atom(A).
+
 pp_fun({Enc,Depth}) ->
     {Letter,Tl} = case Depth of
 		      unlimited -> {"p",[]};