OTP-8522 Avoid duplicated 'undefined' in record field types

The Erlang parser no longer duplicates the singleton type undefined in the
type of record fields without initial value.

1 files changed, 17 insertions, 1 deletions

diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl
index 435464227f..ea91ec5927 100644
--- a/lib/stdlib/src/erl_parse.yrl
+++ b/lib/stdlib/src/erl_parse.yrl
@@ -734,13 +734,29 @@ record_fields([{typed,Expr,TypeInfo}|Fields]) ->
 	case Expr of
 	    {match, _, _, _} -> TypeInfo; %% If we have an initializer.
 	    {atom, La, _} -> 
-                lift_unions(abstract(undefined, La), TypeInfo)
+                case has_undefined(TypeInfo) of
+                    false ->
+                        lift_unions(abstract(undefined, La), TypeInfo);
+                    true ->
+                        TypeInfo
+                end
 	end, 
     [{typed_record_field,Field,TypeInfo1}|record_fields(Fields)];
 record_fields([Other|_Fields]) ->
     ret_err(?line(Other), "bad record field");
 record_fields([]) -> [].
 
+has_undefined({atom,_,undefined}) ->
+    true;
+has_undefined({ann_type,_,[_,T]}) ->
+    has_undefined(T);
+has_undefined({paren_type,_,[T]}) ->
+    has_undefined(T);
+has_undefined({type,_,union,Ts}) ->
+    lists:any(fun has_undefined/1, Ts);
+has_undefined(_) ->
+    false.
+
 term(Expr) ->
     try normalise(Expr)
     catch _:_R -> ret_err(?line(Expr), "bad attribute")