Fix empty case for OCaml 3.11 and above.

diff --git a/pa_bitstring.ml b/pa_bitstring.ml
index 0c09356..1414612 100644 (file)
--- a/pa_bitstring.ml
+++ b/pa_bitstring.ml
@@ -1123,6 +1123,10 @@ EXTEND Gram
       fields = LIST0 patt_field SEP ";";
       "}" ->
        List.concat fields
+    | "{";
+      "_";
+      "}" ->
+       []
     ]
   ];