[compiler] prohibit |. operator

Author: bobzhang

vendor/ocaml/typing/env.ml

@@ -1343,8 +1343,8 @@ and check_value_name name loc =
   (* Note: we could also check here general validity of the
      identifier, to protect against bad identifiers forged by -pp or
      -ppx preprocessors. *)
-
-  if String.length name > 0 && (name.[0] = '#') then
+  if !Clflags.bs_only && name = "|." then raise (Error(Illegal_value_name(loc, name)))  
+  else if String.length name > 0 && (name.[0] = '#') then
     for i = 1 to String.length name - 1 do
       if name.[i] = '#' then
         raise (Error(Illegal_value_name(loc, name)))