example.lua

local t = setmetatable({}, {__name="foobar"})

print(type(t)) --> foobar
print(rawtype(t)) --> table

rawtype.diff

diff --unified -r lua-5.4.0/src/lapi.c lua-5.4.0-rawtype/src/lapi.c
--- lua-5.4.0/src/lapi.c	2020-06-18 16:25:53.000000000 +0200
+++ lua-5.4.0-rawtype/src/lapi.c	2020-11-27 09:31:30.787330086 +0100
@@ -267,6 +267,13 @@
 }
 
 
+LUA_API const char *lua_objtypename (lua_State *L, int t) {
+  api_check(L, LUA_TNONE <= t && t < LUA_NUMTYPES, "invalid type");
+  const TValue *o = index2value(L, t);
+  return luaT_objtypename(L, o);
+}
+
+
 LUA_API int lua_iscfunction (lua_State *L, int idx) {
   const TValue *o = index2value(L, idx);
   return (ttislcf(o) || (ttisCclosure(o)));
diff --unified -r lua-5.4.0/src/lbaselib.c lua-5.4.0-rawtype/src/lbaselib.c
--- lua-5.4.0/src/lbaselib.c	2020-06-18 16:25:53.000000000 +0200
+++ lua-5.4.0-rawtype/src/lbaselib.c	2020-11-27 09:38:19.813573132 +0100
@@ -240,7 +240,7 @@
 }
 
 
-static int luaB_type (lua_State *L) {
+static int luaB_rawtype (lua_State *L) {
   int t = lua_type(L, 1);
   luaL_argcheck(L, t != LUA_TNONE, 1, "value expected");
   lua_pushstring(L, lua_typename(L, t));
@@ -248,6 +248,16 @@
 }
 
 
+static int luaB_type (lua_State *L) {
+  int t = lua_type(L, 1);
+  luaL_argcheck(L, t != LUA_TNONE, 1, "value expected");
+  //lua_pushstring(L, lua_typename(L, t));
+  const char *s = lua_objtypename(L, -1);
+  lua_pushstring(L, s);
+  return 1;
+}
+
+
 static int luaB_next (lua_State *L) {
   luaL_checktype(L, 1, LUA_TTABLE);
   lua_settop(L, 2);  /* create a 2nd argument if there isn't one */
@@ -504,6 +514,7 @@
   {"tonumber", luaB_tonumber},
   {"tostring", luaB_tostring},
   {"type", luaB_type},
+  {"rawtype", luaB_rawtype},
   {"xpcall", luaB_xpcall},
   /* placeholders */
   {LUA_GNAME, NULL},
diff --unified -r lua-5.4.0/src/lua.h lua-5.4.0-rawtype/src/lua.h
--- lua-5.4.0/src/lua.h	2020-06-18 16:25:54.000000000 +0200
+++ lua-5.4.0-rawtype/src/lua.h	2020-11-27 09:33:22.347601208 +0100
@@ -186,6 +186,7 @@
 LUA_API int             (lua_isuserdata) (lua_State *L, int idx);
 LUA_API int             (lua_type) (lua_State *L, int idx);
 LUA_API const char     *(lua_typename) (lua_State *L, int tp);
+LUA_API const char     *(lua_objtypename) (lua_State *L, int tp);
 
 LUA_API lua_Number      (lua_tonumberx) (lua_State *L, int idx, int *isnum);
 LUA_API lua_Integer     (lua_tointegerx) (lua_State *L, int idx, int *isnum);
Only in lua-5.4.0-rawtype/src: tags