Backport fix from PR#10719 (#342)

Author: mshinwell

ocaml/lambda/translcore.ml

@@ -790,7 +790,8 @@ and transl_apply ~scopes
         let body =
           match build_apply handle ((Lvar id_arg, optional)::args') l with
             Lfunction{kind = Curried; params = ids; return;
-                      body = lam; attr; loc} ->
+                      body = lam; attr; loc}
+                when List.length ids < Lambda.max_arity () ->
               Lfunction{kind = Curried;
                         params = (id_arg, Pgenval)::ids;
                         return;