Quote atoms if necessary in types

Atoms in some occurrences were not correctly quoted when formatted to
strings, for instance by the typer program. Example:

    -module(tb).
    -export(['UPPERCASE-FUNCTION-NAME'/0, f1/0, f2/0, f3/0]).
    -record('UPPERCASE-RECORD-NAME', {x}).
    -record(r2, {'UPPERCASE-FIELD-NAME'}).
    -type 'UPPERCASE-TYPE-NAME'() :: integer().

    'UPPERCASE-FUNCTION-NAME'() -> ok.

    f1() -> #'UPPERCASE-RECORD-NAME'{x=1}.

    f2() -> #r2{'UPPERCASE-FIELD-NAME'=1}.

    -spec f3() -> 'UPPERCASE-TYPE-NAME'().
    f3() -> 1.

Given the program above, the output from typer --plt some.plt tb.erl
resulted in the following specs being printed:

    -spec UPPERCASE-FUNCTION-NAME() -> 'ok'.
    -spec f1() -> #UPPERCASE-RECORD-NAME{x::1}.
    -spec f2() -> #r2{UPPERCASE-FIELD-NAME::1}.
    -spec f3() -> UPPERCASE-TYPE-NAME().

This commit changes the output to become the following:

    -spec 'UPPERCASE-FUNCTION-NAME'() -> 'ok'.
    -spec f1() -> #'UPPERCASE-RECORD-NAME'{x::1}.
    -spec f2() -> #r2{'UPPERCASE-FIELD-NAME'::1}.
    -spec f3() -> 'UPPERCASE-TYPE-NAME'().

2 files changed, 12 insertions, 6 deletions

diff --git a/lib/hipe/cerl/erl_types.erl b/lib/hipe/cerl/erl_types.erl
index 1748c1cc16..7ff170776e 100644
--- a/lib/hipe/cerl/erl_types.erl
+++ b/lib/hipe/cerl/erl_types.erl
@@ -211,7 +211,8 @@
 	 record_field_diffs_to_string/2,
 	 subst_all_vars_to_any/1,
 	 lift_list_to_pos_empty/1,
-	 is_erl_type/1
+	 is_erl_type/1,
+	 atom_to_string/1
 	]).
 
 %%-define(DO_ERL_TYPES_TEST, true).
@@ -3360,14 +3361,14 @@ t_to_string(?var(Id), _RecDict) when is_integer(Id) ->
 
 record_to_string(Tag, [_|Fields], FieldNames, RecDict) ->
   FieldStrings = record_fields_to_string(Fields, FieldNames, RecDict, []),
-  "#" ++ atom_to_list(Tag) ++ "{" ++ string:join(FieldStrings, ",") ++ "}".
+  "#" ++ atom_to_string(Tag) ++ "{" ++ string:join(FieldStrings, ",") ++ "}".
 
 record_fields_to_string([F|Fs], [{FName, _DefType}|FDefs], RecDict, Acc) ->
   NewAcc =
     case t_is_any(F) orelse t_is_atom('undefined', F) of
       true -> Acc;
       false ->
-	StrFV = atom_to_list(FName) ++ "::" ++ t_to_string(F, RecDict),
+	StrFV = atom_to_string(FName) ++ "::" ++ t_to_string(F, RecDict),
 	%% ActualDefType = t_subtract(DefType, t_atom('undefined')),
 	%% Str = case t_is_any(ActualDefType) of
 	%% 	  true -> StrFV;
@@ -3393,7 +3394,7 @@ field_diffs([F|Fs], [{FName, DefType}|FDefs], RecDict, Acc) ->
     case t_is_subtype(F, DefType) of
       true -> Acc;
       false ->
-	Str = atom_to_list(FName) ++ "::" ++ t_to_string(DefType, RecDict),
+	Str = atom_to_string(FName) ++ "::" ++ t_to_string(DefType, RecDict),
 	[Str|Acc]
     end,
   field_diffs(Fs, FDefs, RecDict, NewAcc);
@@ -3906,7 +3907,7 @@ t_form_to_string({type, _L, union, Args}) ->
   string:join(t_form_to_string_list(Args), " | ");
 t_form_to_string({type, _L, Name, []} = T) ->
   try t_to_string(t_from_form(T))
-  catch throw:{error, _} -> atom_to_list(Name) ++ "()"
+  catch throw:{error, _} -> atom_to_string(Name) ++ "()"
   end;
 t_form_to_string({type, _L, Name, List}) -> 
   io_lib:format("~w(~s)",
@@ -3920,6 +3921,11 @@ t_form_to_string_list([H|T], Acc) ->
 t_form_to_string_list([], Acc) ->
   lists:reverse(Acc).
 
+-spec atom_to_string(atom()) -> string().
+
+atom_to_string(Atom) ->
+  lists:flatten(io_lib:format("~w", [Atom])).
+
 %%=============================================================================
 %% 
 %% Utilities
diff --git a/lib/typer/src/typer.erl b/lib/typer/src/typer.erl
index e40c4f39cd..fd906c8c46 100644
--- a/lib/typer/src/typer.erl
+++ b/lib/typer/src/typer.erl
@@ -539,7 +539,7 @@ get_type_string(F, A, Info, Mode) ->
       case {Mode, Type} of
 	{file, {contract, _}} -> "";
 	_ ->
-	  Prefix = lists:concat(["-spec ", F]),
+	  Prefix = lists:concat(["-spec ", erl_types:atom_to_string(F)]),
 	  lists:concat([Prefix, TypeStr, "."])
       end;
     true ->