Re: [Lua5.4] lua_toclose will close the wrong value

[Sean Conner <sean@...>]

It was thus said that the Great Sean Conner once stated:
> It was thus said that the Great Roberto Ierusalimschy once stated:
> > >   The manual states for lua_toclose():
> > > 
> > > 	[...] AN INDEX MARKED AS TO-BE-CLOSED SHOULD NOT BE REMOVED FROM
> > > 	THE STACK BY ANY OTHER FUNCTION IN THE API EXCEPT LUA_SETTOP OR
> > > 	LUA_POP.
> > > 
> > > 	[...]
> > > 
> > >   [...] It might be that moving the item to be
> > > cleaned is disallowed as well and the manual doesn't mention it.
> >                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > It seems it does.
> 
>   No, it wasn't removed, it was *moved*.  

  I've played around with the code a bit more.  This code:

	static int close(lua_State *L)
	{
	  (void)L;
	  printf("CLOSING!\n");
	  return 0;
	}
	
	static const luaL_Reg mt[] =
	{
	  { "__close" , close } ,
	  { NULL      , NULL  }
	};
	
	int luaopen_toclose(lua_State *L)
	{
					// slot 1 - string "toclose"
					// slot 2 - string "./toclose"
	    lua_newtable(L);		// slot three - table
	    luaL_newlib(L,mt);
	    lua_setmetatable(L,-2);	
	    lua_toclose(L, -1);
	    lua_pushinteger(L,1);	// slot four - integer
	    lua_insert(L,1);		// stack now 1)int 2)str 3)str 4)table
	    return 1;
	}

results in:

	[spc]lucy:/tmp>~/apps/lua-5.4/lua 
	Lua 5.4.0  Copyright (C) 1994-2019 Lua.org, PUC-Rio
	> require "toclose"
	attempt to close non-closable variable '(C temporary)'
	stack traceback:
	        [C]: in function 'require'
	        stdin:1: in main chunk
	        [C]: in ?

  I'm thinking the manual needs to state, "an index marked as 'to-be-closed'
should not be moved, nor removed by any other function in the API except
lua_settop() or lua_pop() ..."

  -spc (Would have thought the value would be marked, not the slot ... )