Re: lua 5.3.2 introduced a bug related to coroutines

["Soni L." <fakedme@...>]

On 17/03/16 08:07 PM, 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 ?
It's even worse than it looks...

--bug.lua--
local function yieldFirst(it)
    return coroutine.wrap(function()
        local v = it()
        coroutine.yield(v)
        print(v) -- ???
    end)
end

local text = "1 2 3"
local it = text:gmatch("(%d+)")
local head = yieldFirst(it)
local one = head()
print(one)
head() -- ???
assert(one == '1')
--end--

$ lua bug.lua
function: 0x11c9030
function: 0x11c9030
lua: bug.lua:15: assertion failed!
stack traceback:
    [C]: in function 'assert'
    bug.lua:15: in main chunk
    [C]: in ?

Either something really bad is happening (because it's affecting locals, 
not just the yielded values), or string iterators break across coroutines.

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