stdlib: Allow characters in types and constant patterns

Characters ($char) can be used in constant pattern expressions. They
can also be used in types and contracts.

5 files changed, 42 insertions, 0 deletions

diff --git a/lib/dialyzer/test/small_SUITE_data/results/chars b/lib/dialyzer/test/small_SUITE_data/results/chars
new file mode 100644
index 0000000000..2c1f8f8d17
--- /dev/null
+++ b/lib/dialyzer/test/small_SUITE_data/results/chars
@@ -0,0 +1,4 @@
+
+chars.erl:29: Invalid type specification for function chars:f/1. The success typing is (#{'b':=50}) -> 'ok'
+chars.erl:32: Function t1/0 has no local return
+chars.erl:32: The call chars:f(#{'b':=50}) breaks the contract (#{'a':=49,'b'=>50,'c'=>51}) -> 'ok'
diff --git a/lib/dialyzer/test/small_SUITE_data/src/chars.erl b/lib/dialyzer/test/small_SUITE_data/src/chars.erl
new file mode 100644
index 0000000000..1e9c8ab6b9
--- /dev/null
+++ b/lib/dialyzer/test/small_SUITE_data/src/chars.erl
@@ -0,0 +1,32 @@
+-module(chars).
+
+%% ERL-313
+
+-export([t/0]).
+-export([t1/0]).
+
+-record(r, {f :: $A .. $Z}).
+
+-type cs() :: $A..$Z | $a .. $z | $/.
+
+-spec t() -> $0-$0..$9-$0| $?.
+
+t() ->
+    c(#r{f = $z - 3}),
+    c($z - 3),
+    c($B).
+
+-spec c(cs()) -> $3-$0..$9-$0.
+
+c($A + 1) -> 2;
+c(C) ->
+    case C of
+        $z - 3 -> 3;
+        #r{f = $z - 3} -> 7
+    end.
+
+%% Display contract with character in warning:
+-spec f(#{a := $1, b => $2, c => $3}) -> ok. % invalid type spec
+f(_) -> ok.
+
+t1() -> f(#{b => $2}). % breaks the  contract
diff --git a/lib/hipe/cerl/erl_types.erl b/lib/hipe/cerl/erl_types.erl
index 226a5d0f61..81a1c89744 100644
--- a/lib/hipe/cerl/erl_types.erl
+++ b/lib/hipe/cerl/erl_types.erl
@@ -4542,6 +4542,8 @@ from_form({atom, _L, Atom}, _S, _D, L, C) ->
   {t_atom(Atom), L, C};
 from_form({integer, _L, Int}, _S, _D, L, C) ->
   {t_integer(Int), L, C};
+from_form({char, _L, Char}, _S, _D, L, C) ->
+  {t_integer(Char), L, C};
 from_form({op, _L, _Op, _Arg} = Op, _S, _D, L, C) ->
   case erl_eval:partial_eval(Op) of
     {integer, _, Val} ->
@@ -5056,6 +5058,7 @@ check_record_fields({remote_type, _L, [{atom, _, _}, {atom, _, _}, Args]},
   list_check_record_fields(Args, S, C);
 check_record_fields({atom, _L, _}, _S, C) -> C;
 check_record_fields({integer, _L, _}, _S, C) -> C;
+check_record_fields({char, _L, _}, _S, C) -> C;
 check_record_fields({op, _L, _Op, _Arg}, _S, C) -> C;
 check_record_fields({op, _L, _Op, _Arg1, _Arg2}, _S, C) -> C;
 check_record_fields({type, _L, tuple, any}, _S, C) -> C;
@@ -5157,6 +5160,7 @@ t_form_to_string({var, _L, Name}) -> atom_to_list(Name);
 t_form_to_string({atom, _L, Atom}) -> 
   io_lib:write_string(atom_to_list(Atom), $'); % To quote or not to quote... '
 t_form_to_string({integer, _L, Int}) -> integer_to_list(Int);
+t_form_to_string({char, _L, Char}) -> integer_to_list(Char);
 t_form_to_string({op, _L, _Op, _Arg} = Op) ->
   case erl_eval:partial_eval(Op) of
     {integer, _, _} = Int -> t_form_to_string(Int);
diff --git a/lib/stdlib/src/erl_eval.erl b/lib/stdlib/src/erl_eval.erl
index 40a34aa30f..eafee346eb 100644
--- a/lib/stdlib/src/erl_eval.erl
+++ b/lib/stdlib/src/erl_eval.erl
@@ -1306,6 +1306,7 @@ partial_eval(Expr) ->
 ev_expr({op,_,Op,L,R}) -> erlang:Op(ev_expr(L), ev_expr(R));
 ev_expr({op,_,Op,A}) -> erlang:Op(ev_expr(A));
 ev_expr({integer,_,X}) -> X;
+ev_expr({char,_,X})    -> X;
 ev_expr({float,_,X})   -> X;
 ev_expr({atom,_,X})    -> X;
 ev_expr({tuple,_,Es}) ->
diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl
index 4f38256e6b..5656155c53 100644
--- a/lib/stdlib/src/erl_parse.yrl
+++ b/lib/stdlib/src/erl_parse.yrl
@@ -156,6 +156,7 @@ type -> '#' atom '{' field_types '}'      : {type, ?anno('$1'),
                                              record, ['$2'|'$4']}.
 type -> binary_type                       : '$1'.
 type -> integer                           : '$1'.
+type -> char                              : '$1'.
 type -> 'fun' '(' ')'                     : {type, ?anno('$1'), 'fun', []}.
 type -> 'fun' '(' fun_type_100 ')'        : '$3'.