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-rw-r--r--lib/stdlib/src/erl_parse.yrl5
1 files changed, 5 insertions, 0 deletions
diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl
index 69807aad83..5287f55e59 100644
--- a/lib/stdlib/src/erl_parse.yrl
+++ b/lib/stdlib/src/erl_parse.yrl
@@ -112,6 +112,7 @@ type_guards -> type_guard ',' type_guards : ['$1'|'$3'].
type_guard -> atom '(' top_types ')' : {type, ?line('$1'), constraint,
['$1', '$3']}.
+type_guard -> var '::' top_type : build_def('$1', '$3').
top_types -> top_type : ['$1'].
top_types -> top_type ',' top_types : ['$1'|'$3'].
@@ -597,6 +598,10 @@ find_arity_from_specs([Spec|_]) ->
{type, _, 'fun', [{type, _, product, Args},_]} = Fun,
length(Args).
+build_def(LHS, Types) ->
+ IsSubType = {atom, ?line(LHS), is_subtype},
+ {type, ?line(LHS), constraint, [IsSubType, [LHS, Types]]}.
+
lift_unions(T1, {type, _La, union, List}) ->
{type, ?line(T1), union, [T1|List]};
lift_unions(T1, T2) ->