Re: [Tarantool-patches] [PATCH luajit] test: adapt tests checking traceback in tail call

[Sergey Kaplun via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Hi, Maxim!

Thanks for the patch!

LGTM except a few nits, regarding the commit message.

On 24.09.21, Maxim Kokryashkin wrote:
> LuaJIT does not provide information about tail calls

Typo: s/calls/calls,/

> unlike, Lua 5.1 does, so a traceback in LuaJIT may be different.
> 
> Consider this chunck of code:
> ```
> local function checktraceback (co, p)
>   local tb = debug.traceback(co)
>   local i = 0
>   for l in string.gmatch(tb, "[^\n]+\n?") do
>     assert(i == 0 or string.find(l, p[i]))
>     i = i+1
>   end
>   assert(p[i] == nil)
> end
> 
> local function f (n)
>   if n > 0 then return f(n-1)
>   else coroutine.yield() end
> end
> 
> local co = coroutine.create(f)
> coroutine.resume(co, 3)
> checktraceback(co, {"yield", "db.lua", "tail", "tail", "tail"})
> ```
> 
> For LuaJIT traceback looks like the following:
> ```
> stack traceback:
>         [C]: in function 'yield'
>         db.lua:436: in function <db.lua:434>
> ```
> 
> And for Lua 5.1 it looks like the following:
> ```
> stack traceback:
>         [C]: in function 'yield'
>         db.lua:436: in function <db.lua:434>
>         (tail call): ?
>         (tail call): ?
>         (tail call): ?
> ```

Please provide a simple example in the commit message. This is too
monstrous. Also, it is a good practice to mention what the patch does.

> 
> Closes tarantool/tarantool#5703
> Part of tarantool/tarantool#5845
> Part of tarantool/tarantool#4473

Looks like it should be 5870 instead 4473. Also, 5845 is already
closed.

> ---
> Issue: https://github.com/tarantool/tarantool/issues/5703
> GitHub branch: https://github.com/tarantool/luajit/tree/fckxorg/gh-5703-adapt-traceback-tail-call-PUC-Rio
> 
>  test/PUC-Rio-Lua-5.1-tests/db.lua | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/test/PUC-Rio-Lua-5.1-tests/db.lua b/test/PUC-Rio-Lua-5.1-tests/db.lua
> index 56f59ea8..f254cde6 100644
> --- a/test/PUC-Rio-Lua-5.1-tests/db.lua
> +++ b/test/PUC-Rio-Lua-5.1-tests/db.lua

<snipped>

> -- 
> 2.33.0
> 

-- 
Best regards,
Sergey Kaplun