[Tarantool-patches] [PATCH v2 luajit 23/30] test: disable PUC Lua test for fast function name

[Igor Munkin]

Sergey,

Thanks for the patch! Please consider the comments below.

On 26.03.21, Sergey Kaplun wrote:
> LuaJIT can't determine bytecode position for non Lua functions
> (in particular for fast functions) and, therefore, detect built-in
> function names for errors in tail calls.

Side note: here is the inconsistency in your usage of possessive nouns.

> 
> This patch disables test that checks name of built-in functions

Typo: s/disables test/disables the test/.
Typo: s/checks name/checks the name/.

> reported in error in tail call.
> 
> Part of tarantool/tarantool#5845
> Part of tarantool/tarantool#4473
> ---
>  test/PUC-Lua-5.1-tests/errors.lua | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/test/PUC-Lua-5.1-tests/errors.lua b/test/PUC-Lua-5.1-tests/errors.lua
> index cf24e40..af776a7 100644
> --- a/test/PUC-Lua-5.1-tests/errors.lua
> +++ b/test/PUC-Lua-5.1-tests/errors.lua
> @@ -105,9 +105,13 @@ while 1 do
>    insert(prefix, a)
>  end]], "global 'insert'")
>  
> -checkmessage([[  -- tail call
> -  return math.sin("a")
> -]], "'sin'")
> +-- LuaJIT: Can't determine bytecode position for non Lua functions
> +-- (in particular for fast functions) and, therefore, detect fast
> +-- function names for errors in tail calls.

This is kinda gibberish. I've tried the following snippets and can't
understand what do you mean by this comment.

| $ luajit -e 'function q(a) return math.sin(a) end q("a")'
| luajit: (command line):1: bad argument #1 to 'q' (number expected, got string)
| stack traceback:
|         [C]: in function 'q'
|         (command line):1: in main chunk
|         [C]: at 0x5610e8497eb0
| $ luajit -e 'loadstring("return math.sin([[a]])")()'
| luajit: (command line):1: bad argument #1 to '?' (number expected, got string)
| stack traceback:
|         [builtin#43]: at 0x7fc0f807ad10
|         (command line):1: in main chunk
|         [C]: at 0x55c1e85c7eb0

I understand the first result. The second result surprised me, but I've
never investigated how loadstring call works (it looks like specifics of
VARG frame, but this is a wild guess). But neither of them fits your
explanation. The root cause is the same: callee uses caller frame, since
caller doesn't need it anymore. Could you please clarify yours?

> +-- The test is disabled for LuaJIT.
> +-- checkmessage([[  -- tail call
> +--   return math.sin("a")
> +-- ]], "'sin'")
>  
>  checkmessage([[collectgarbage("nooption")]], "invalid option")
>  
> -- 
> 2.31.0
> 

-- 
Best regards,
IM