[Tarantool-patches] [PATCH v2 luajit 16/30] test: adapt PUC Lua test for %q in fmt for LuaJIT

[Igor Munkin]

Sergey,

Thanks for your patch! Please consider my comments below.

On 26.03.21, Sergey Kaplun wrote:
> LuaJIT: LuaJIT since v2.0.0-beta6 has extension from Lua 5.2:

Looks like you just copied the comment below. There is no need for
'LuaJIT:' here.

> string.format(): %q reversible.
> See also https://luajit.org/extensions.html#lua52.
> 
> In Lua 5.1 string.format() does not accept string values containing
> embedded zeros, except as arguments to the '%q' option.
> In Lua 5.2 '\0' is not handled differently from other
> control chars in string.format('%q', ...).
> See commit 7cc981c14067d4b0e774a6bfb0acfc2f5c911f0d
> (string.format("%q", str) is now fully reversible
> (from Lua 5.2).).

Well, I honestly don't understand what is changed in *semantics*. I've
tried the following command with Lua 5.2, Lua 5.1 and LuaJIT 2.0.5 as an
interpreter being tested
| <interp> -e 'print(string.format("%q", "\0"))'

I understand the semantics of "%q", but was it just a bug in Lua 5.1?
What does "fully reversible" mean in this context?

I understand only the fact the behaviour differs and you reimplemented
the test assertion according to Lua 5.2 testing suite. That's all.

I found not a single word regarding this issue in Lua bugs[1] page,
except invalid handling of \r[2]. Is there any issue/page with a more
verbose explanation what has been changed in 7cc981c?

> 
> This patch adapts test for LuaJIT and Lua 5.2 behaviour considering
> test from Lua 5.2 test suite taken from

Typo: s/considering test/considering the test/.

> https://www.lua.org/tests/lua-5.2.0-tests.tar.gz.
> 
> Closes tarantool/tarantool#5710

As we discussed before: s/Closes/Resolves/.

> Part of tarantool/tarantool#5845
> Part of tarantool/tarantool#4473
> ---
>  test/PUC-Lua-5.1-tests/strings.lua | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/test/PUC-Lua-5.1-tests/strings.lua b/test/PUC-Lua-5.1-tests/strings.lua
> index 237dbad..7c1dfb8 100644
> --- a/test/PUC-Lua-5.1-tests/strings.lua
> +++ b/test/PUC-Lua-5.1-tests/strings.lua
> @@ -102,7 +102,17 @@ print('+')
>  
>  x = '"?lo"\n\\'
>  assert(string.format('%q%s', x, x) == '"\\"?lo\\"\\\n\\\\""?lo"\n\\')
> -assert(string.format('%q', "\0") == [["\000"]])
> +-- LuaJIT: LuaJIT since v2.0.0-beta6 has extension from Lua 5.2:
> +-- string.format(): %q reversible.
> +-- In Lua 5.1 string.format() does not accept string values
> +-- containing embedded zeros, except as arguments to the q option.
> +-- In Lua 5.2 '\0' is not handled differently from other
> +-- control chars in string.format('%q', ...).
> +-- See commit 7cc981c14067d4b0e774a6bfb0acfc2f5c911f0d
> +-- (string.format("%q", str) is now fully reversible
> +-- (from Lua 5.2).).
> +-- Test is adapted from PUC-Rio Lua 5.2 test suite.
> +assert(string.format('%q', "\0") == [["\0"]])
>  assert(string.format("\0%c\0%c%x\0", string.byte("?"), string.byte("b"), 140) ==
>                "\0?\0b8c\0")
>  assert(string.format('') == "")
> -- 
> 2.31.0
> 

[1]: https://www.lua.org/bugs.html#5.1
[2]: https://www.lua.org/bugs.html#5.1-4

-- 
Best regards,
IM