FFI: Always fall back to metamethods for cdata length/concat.

Thanks to Egor Skriptunoff.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/lj_crecord.c b/src/lj_crecord.c
index 99344b79..6e3c36a1 100644
--- a/src/lj_crecord.c
+++ b/src/lj_crecord.c
@@ -1443,8 +1443,10 @@ void LJ_FASTCALL recff_cdata_arith(jit_State *J, RecordFFData *rd)
   }
   {
     TRef tr;
-    if (!(tr = crec_arith_int64(J, sp, s, (MMS)rd->data)) &&
-        !(tr = crec_arith_ptr(J, sp, s, (MMS)rd->data)) &&
+    MMS mm = (MMS)rd->data;
+    if ((mm == MM_len || mm == MM_concat ||
+         (!(tr = crec_arith_int64(J, sp, s, mm)) &&
+          !(tr = crec_arith_ptr(J, sp, s, mm)))) &&
         !(tr = crec_arith_meta(J, sp, s, cts, rd)))
       return;
     J->base[0] = tr;