FFI: Allow cdata indexing with integer cdata.

src/lj_cdata.c

@@ -71,6 +71,7 @@ CType *lj_cdata_index(CTState *cts, GCcdata *cd, cTValue *key, uint8_t **pp,
 {
   uint8_t *p = (uint8_t *)cdataptr(cd);
   CType *ct = ctype_get(cts, cd->typeid);
+  ptrdiff_t idx;
 
   /* Resolve reference for cdata object. */
   if (ctype_isref(ct->info)) {
@@ -88,8 +89,8 @@ collect_attrib:
   lua_assert(!ctype_isref(ct->info));  /* Interning rejects refs to refs. */
 
   if (tvisnum(key)) {  /* Numeric key. */
-    ptrdiff_t idx = LJ_64 ? (ptrdiff_t)numV(key) :
-			    (ptrdiff_t)lj_num2int(numV(key));
+    idx = LJ_64 ? (ptrdiff_t)numV(key) : (ptrdiff_t)lj_num2int(numV(key));
+  integer_key:
     if (ctype_ispointer(ct->info)) {
       CTSize sz = lj_ctype_size(cts, ctype_cid(ct->info));  /* Element size. */
       if (sz != CTSIZE_INVALID) {
@@ -101,6 +102,15 @@ collect_attrib:
 	return ct;
       }
     }
+  } else if (tviscdata(key)) {  /* Integer cdata key. */
+    GCcdata *cdk = cdataV(key);
+    CType *ctk = ctype_raw(cts, cdk->typeid);
+    if (ctype_isenum(ctk->info)) ctk = ctype_child(cts, ctk);
+    if (ctype_isinteger(ctk->info)) {
+      lj_cconv_ct_ct(cts, ctype_get(cts, CTID_INT_PSZ), ctk,
+		     (uint8_t *)&idx, cdataptr(cdk), 0);
+      goto integer_key;
+    }
   } else if (tvisstr(key)) {  /* String key. */
     GCstr *name = strV(key);
     if (ctype_isptr(ct->info)) {  /* Automatically perform '->'. */