From Lua 5.2: Add luaL_traceback().

src/lib_debug.c

@@ -383,55 +383,13 @@ LJLIB_CF(debug_debug)
 
 LJLIB_CF(debug_traceback)
 {
-  int level;
-  int firstpart = 1;  /* still before eventual `...' */
   int arg;
   lua_State *L1 = getthread(L, &arg);
-  lua_Debug ar;
-  if (lua_isnumber(L, arg+2)) {
-    level = (int)lua_tointeger(L, arg+2);
-    lua_pop(L, 1);
-  }
+  const char *msg = lua_tostring(L, arg+1);
+  if (msg == NULL && L->top > L->base+arg)
+    L->top = L->base+arg+1;
   else
-    level = (L == L1) ? 1 : 0;  /* level 0 may be this own function */
-  if (lua_gettop(L) == arg)
-    lua_pushliteral(L, "");
-  else if (!lua_isstring(L, arg+1)) return 1;  /* message is not a string */
-  else lua_pushliteral(L, "\n");
-  lua_pushliteral(L, "stack traceback:");
-  while (lua_getstack(L1, level++, &ar)) {
-    if (level > LEVELS1 && firstpart) {
-      /* no more than `LEVELS2' more levels? */
-      if (!lua_getstack(L1, level+LEVELS2, &ar)) {
-	level--;  /* keep going */
-      } else {
-	lua_pushliteral(L, "\n\t...");  /* too many levels */
-	/* This only works with LuaJIT 2.x. Avoids O(n^2) behaviour. */
-	lua_getstack(L1, -10, &ar);
-	level = ar.i_ci - LEVELS2;
-      }
-      firstpart = 0;
-      continue;
-    }
-    lua_pushliteral(L, "\n\t");
-    lua_getinfo(L1, "Snl", &ar);
-    lua_pushfstring(L, "%s:", ar.short_src);
-    if (ar.currentline > 0)
-      lua_pushfstring(L, "%d:", ar.currentline);
-    if (*ar.namewhat != '\0') {  /* is there a name? */
-      lua_pushfstring(L, " in function " LUA_QS, ar.name);
-    } else {
-      if (*ar.what == 'm')  /* main? */
-	lua_pushfstring(L, " in main chunk");
-      else if (*ar.what == 'C' || *ar.what == 't')
-	lua_pushliteral(L, " ?");  /* C function or tail call */
-      else
-	lua_pushfstring(L, " in function <%s:%d>",
-			ar.short_src, ar.linedefined);
-    }
-    lua_concat(L, lua_gettop(L) - arg);
-  }
-  lua_concat(L, lua_gettop(L) - arg);
+    luaL_traceback(L, L1, msg, lj_lib_optint(L, arg+2, (L == L1)));
   return 1;
 }