[Tarantool-patches] [PATCH luajit] Restore state when recording __concat metamethod throws an error.

[Sergey Kaplun]

One more minor update below.

On 13.09.24, Sergey Kaplun via Tarantool-patches wrote:
> Hi, Sergey!
> Thanks for the review!
> 
> On 13.09.24, Sergey Bronnikov wrote:
> > Hi, Sergey,
> > 
> > thanks for the patch! LGTM with a minor comment. See below.
> > 
> > On 21.08.2024 11:23, Sergey Kaplun wrote:
> > 
> > 
> > <snipped>
> > 
> > > +-- Need to use metamethod call in the concat recording.
> > > +debug.setmetatable(nil, {
> > I propose to add a comment that explain why `nil` is used here.
> 
> I've removed the nil usage to avoid confusion.
> Branch is rebased on the current master and force-pushed.
> ===================================================================
> diff --git a/test/tarantool-tests/lj-1234-err-in-record-concat.test.lua b/test/tarantool-tests/lj-1234-err-in-record-concat.test.lua
> index 9abaeba5..4fe02708 100644
> --- a/test/tarantool-tests/lj-1234-err-in-record-concat.test.lua
> +++ b/test/tarantool-tests/lj-1234-err-in-record-concat.test.lua
> @@ -12,12 +12,13 @@ test:plan(2)
>  
>  jit.opt.start('hotloop=1')
>  
> -local __concat = function(v1, v2)
> -    return tostring(v1) .. tostring(v2)
> +local __concat = function()
> +  return ''
>  end
>  
>  -- Need to use metamethod call in the concat recording.
> -debug.setmetatable(nil, {
> +-- Let's use a table with the metamethod.
> +local concatable_t = setmetatable({}, {
>    __concat = __concat,
>  })
>  
> @@ -31,7 +32,7 @@ local function test_concat_p()
>      -- `lj_record_ret()` restore the Lua stack (before the patch),
>      -- it becomes unbalanced after the instruction recording
>      -- attempt.
> -    local _ = {} .. (nil .. nil)
> +    local _ = {} .. (concatable_t .. concatable_t)
>    end
>  end
>  
> ===================================================================

Added more verbose description:

===================================================================
diff --git a/test/tarantool-tests/lj-1234-err-in-record-concat.test.lua b/test/tarantool-tests/lj-1234-err-in-record-concat.test.lua
index 4fe02708..75736e74 100644
--- a/test/tarantool-tests/lj-1234-err-in-record-concat.test.lua
+++ b/test/tarantool-tests/lj-1234-err-in-record-concat.test.lua
@@ -17,7 +17,8 @@ local __concat = function()
 end
 
 -- Need to use metamethod call in the concat recording.
--- Let's use a table with the metamethod.
+-- We may use any object with a metamethod, but let's use a table
+-- as the most common one.
 local concatable_t = setmetatable({}, {
   __concat = __concat,
 })
===================================================================

> 
> > > +  __concat = __concat,
> > > +})
> > > +
> 
> <snipped>
> 
> -- 
> Best regards,
> Sergey Kaplun

-- 
Best regards,
Sergey Kaplun