Fix Lua/C API typecheck error for special indexes.

1 files changed, 17 insertions, 3 deletions

diff --git a/src/lj_err.c b/src/lj_err.c
index 52631b8e..081bfde4 100644
--- a/src/lj_err.c
+++ b/src/lj_err.c
@@ -726,9 +726,23 @@ LJ_NOINLINE void lj_err_arg(lua_State *L, int narg, ErrMsg em)
 /* Typecheck error for arguments. */
 LJ_NOINLINE void lj_err_argtype(lua_State *L, int narg, const char *xname)
 {
-  TValue *o = narg < 0 ? L->top + narg : L->base + narg-1;
-  const char *tname = o < L->top ? lj_typename(o) : lj_obj_typename[0];
-  const char *msg = lj_str_pushf(L, err2msg(LJ_ERR_BADTYPE), xname, tname);
+  const char *tname, *msg;
+  if (narg <= LUA_REGISTRYINDEX) {
+    if (narg >= LUA_GLOBALSINDEX) {
+      tname = lj_obj_itypename[~LJ_TTAB];
+    } else {
+      GCfunc *fn = curr_func(L);
+      int idx = LUA_GLOBALSINDEX - narg;
+      if (idx <= fn->c.nupvalues)
+        tname = lj_typename(&fn->c.upvalue[idx-1]);
+      else
+        tname = lj_obj_typename[0];
+    }
+  } else {
+    TValue *o = narg < 0 ? L->top + narg : L->base + narg-1;
+    tname = o < L->top ? lj_typename(o) : lj_obj_typename[0];
+  }
+  msg = lj_str_pushf(L, err2msg(LJ_ERR_BADTYPE), xname, tname);
   err_argmsg(L, narg, msg);
 }