Re: lua 5.3.2 introduced a bug related to coroutines

[Marc Balmer <marc@...>]

> Am 18.03.2016 um 02:07 schrieb William Ahern <william@25thandClement.com>:
> 
> On Fri, Mar 18, 2016 at 02:07:11AM +0300, Nagaev Boris wrote:
>> $ cat bug.lua
>> local function yieldFirst(it)
>>    return coroutine.wrap(function()
>>        coroutine.yield(it())
>>    end)
>> end
>> 
>> local text = "1 2 3"
>> local it = text:gmatch("(%d+)")
>> local head = yieldFirst(it)
>> local one = head()
>> print(one)
>> assert(one == '1')
>> 
>> $ ./lua-5.3.1/src/lua bug.lua
>> 1
>> $ ./lua-5.3.2/src/lua bug.lua
>> function: 0x243f820
>> ./lua-5.3.2/src/lua: bug.lua:12: assertion failed!
>> stack traceback:
>>        [C]: in function 'assert'
>>        bug.lua:12: in main chunk
>>        [C]: in ?
>> 
> 
> My first guess is that lstrlib.c:gmatch is storing the lua_State object (see
> prepstate) used when creating the closure. When the closure is invoked, it
> uses this original lua_State instead of the current lua_State invoking the
> closure. But the original lua_State is busy resuming the new lua_State.
> 
> The immediate solution might be to add
> 
> 	gm->ms.L = L

Where would one add that, right before

      return push_captures(&gm->ms, src, e);

?

> 


> to strlib.c:gmatch_aux. I haven't tested it. It might result in wrong error
> messages? Maybe not. I don't know why lua_State is being stored in
> MatchState except to reduce the number of arguments needed to invoke all the
> other routines in strlib.c.
> 
>