[PATCH] lua: fix decimal comparison with box.NULL

[PATCH] lua: fix decimal comparison with box.NULL

[Serge Petrenko]

This problem is similar to the one fixed in commit
3c6c1cc96a1a510493c21c472565d4063e403ba2 (lua:fix decimal comparison
with nil)
We should handle box.NULL the same way.

Closes #4454
---
https://github.com/tarantool/tarantool/issues/4454
https://github.com/tarantool/tarantool/tree/sp/gh-4454-decimal-cmp-null

 src/lua/decimal.c         |  3 ++-
 test/app/decimal.result   | 30 ++++++++++++++++++++++++++++++
 test/app/decimal.test.lua |  8 ++++++++
 3 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/src/lua/decimal.c b/src/lua/decimal.c
index 23e50ba68..8905a0b9d 100644
--- a/src/lua/decimal.c
+++ b/src/lua/decimal.c
@@ -235,7 +235,8 @@ static int
 ldecimal_eq(struct lua_State *L)
 {
 	assert(lua_gettop(L) == 2);
-	if (lua_isnil(L, 1) || lua_isnil(L, 2)) {
+	if (lua_isnil(L, 1) || lua_isnil(L, 2) ||
+	    luaL_isnull(L, 1) || luaL_isnull(L, 2)) {
 		lua_pushboolean(L, false);
 		return 1;
 	}
diff --git a/test/app/decimal.result b/test/app/decimal.result
index 8251e13d8..90d0984b0 100644
--- a/test/app/decimal.result
+++ b/test/app/decimal.result
@@ -248,6 +248,36 @@ a <= nil
  | ---
  | - error: '[string "return a <= nil "]:1: attempt to compare decimal with nil'
  | ...
+-- and with box.NULL
+--
+a == box.NULL
+ | ---
+ | - false
+ | ...
+a ~= box.NULL
+ | ---
+ | - true
+ | ...
+a > box.NULL
+ | ---
+ | - error: '[string "return a > box.NULL "]:1: expected decimal, number or string as
+ |     1 argument'
+ | ...
+a < box.NULL
+ | ---
+ | - error: '[string "return a < box.NULL "]:1: expected decimal, number or string as
+ |     2 argument'
+ | ...
+a >= box.NULL
+ | ---
+ | - error: '[string "return a >= box.NULL "]:1: expected decimal, number or string as
+ |     1 argument'
+ | ...
+a <= box.NULL
+ | ---
+ | - error: '[string "return a <= box.NULL "]:1: expected decimal, number or string as
+ |     2 argument'
+ | ...
 
 decimal.sqrt(a)
  | ---
diff --git a/test/app/decimal.test.lua b/test/app/decimal.test.lua
index d83522b45..79189a2f5 100644
--- a/test/app/decimal.test.lua
+++ b/test/app/decimal.test.lua
@@ -69,6 +69,14 @@ a > nil
 a < nil
 a >= nil
 a <= nil
+-- and with box.NULL
+--
+a == box.NULL
+a ~= box.NULL
+a > box.NULL
+a < box.NULL
+a >= box.NULL
+a <= box.NULL
 
 decimal.sqrt(a)
 decimal.ln(a)
-- 
2.20.1 (Apple Git-117)

Re: [PATCH] lua: fix decimal comparison with box.NULL

[Vladimir Davydov]

On Tue, Aug 27, 2019 at 02:22:09PM +0300, Serge Petrenko wrote:
> This problem is similar to the one fixed in commit
> 3c6c1cc96a1a510493c21c472565d4063e403ba2 (lua:fix decimal comparison
> with nil)
> We should handle box.NULL the same way.
> 
> Closes #4454
> ---
> https://github.com/tarantool/tarantool/issues/4454
> https://github.com/tarantool/tarantool/tree/sp/gh-4454-decimal-cmp-null
> 
>  src/lua/decimal.c         |  3 ++-
>  test/app/decimal.result   | 30 ++++++++++++++++++++++++++++++
>  test/app/decimal.test.lua |  8 ++++++++
>  3 files changed, 40 insertions(+), 1 deletion(-)
> 
> diff --git a/src/lua/decimal.c b/src/lua/decimal.c
> index 23e50ba68..8905a0b9d 100644
> --- a/src/lua/decimal.c
> +++ b/src/lua/decimal.c
> @@ -235,7 +235,8 @@ static int
>  ldecimal_eq(struct lua_State *L)
>  {
>  	assert(lua_gettop(L) == 2);
> -	if (lua_isnil(L, 1) || lua_isnil(L, 2)) {
> +	if (lua_isnil(L, 1) || lua_isnil(L, 2) ||
> +	    luaL_isnull(L, 1) || luaL_isnull(L, 2)) {
>  		lua_pushboolean(L, false);
>  		return 1;
>  	}
> diff --git a/test/app/decimal.result b/test/app/decimal.result
> index 8251e13d8..90d0984b0 100644
> --- a/test/app/decimal.result
> +++ b/test/app/decimal.result
> @@ -248,6 +248,36 @@ a <= nil
>   | ---
>   | - error: '[string "return a <= nil "]:1: attempt to compare decimal with nil'
>   | ...
> +-- and with box.NULL
> +--
> +a == box.NULL
> + | ---
> + | - false
> + | ...
> +a ~= box.NULL
> + | ---
> + | - true
> + | ...
> +a > box.NULL
> + | ---
> + | - error: '[string "return a > box.NULL "]:1: expected decimal, number or string as
> + |     1 argument'
> + | ...

1 argument?

> +a < box.NULL
> + | ---
> + | - error: '[string "return a < box.NULL "]:1: expected decimal, number or string as
> + |     2 argument'
> + | ...

2 argument?

Why does the error message differ for the two seemingly equivalent
cases? What's "1 argument"?

Note, in case of comparison with nil the error message is different:

 | - error: '[string "return a > nil "]:1: attempt to compare decimal with nil'
 | - error: '[string "return a < nil "]:1: attempt to compare decimal with nil'

Re: [tarantool-patches] Re: [PATCH] lua: fix decimal comparison with box.NULL

[Serge Petrenko]

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> 27 авг. 2019 г., в 15:04, Vladimir Davydov <vdavydov.dev@gmail.com> написал(а):
> 
> On Tue, Aug 27, 2019 at 02:22:09PM +0300, Serge Petrenko wrote:
>> This problem is similar to the one fixed in commit
>> 3c6c1cc96a1a510493c21c472565d4063e403ba2 (lua:fix decimal comparison
>> with nil)
>> We should handle box.NULL the same way.
>> 
>> Closes #4454
>> ---
>> https://github.com/tarantool/tarantool/issues/4454
>> https://github.com/tarantool/tarantool/tree/sp/gh-4454-decimal-cmp-null
>> 
>> src/lua/decimal.c         |  3 ++-
>> test/app/decimal.result   | 30 ++++++++++++++++++++++++++++++
>> test/app/decimal.test.lua |  8 ++++++++
>> 3 files changed, 40 insertions(+), 1 deletion(-)
>> 
>> diff --git a/src/lua/decimal.c b/src/lua/decimal.c
>> index 23e50ba68..8905a0b9d 100644
>> --- a/src/lua/decimal.c
>> +++ b/src/lua/decimal.c
>> @@ -235,7 +235,8 @@ static int
>> ldecimal_eq(struct lua_State *L)
>> {
>> 	assert(lua_gettop(L) == 2);
>> -	if (lua_isnil(L, 1) || lua_isnil(L, 2)) {
>> +	if (lua_isnil(L, 1) || lua_isnil(L, 2) ||
>> +	    luaL_isnull(L, 1) || luaL_isnull(L, 2)) {
>> 		lua_pushboolean(L, false);
>> 		return 1;
>> 	}
>> diff --git a/test/app/decimal.result b/test/app/decimal.result
>> index 8251e13d8..90d0984b0 100644
>> --- a/test/app/decimal.result
>> +++ b/test/app/decimal.result
>> @@ -248,6 +248,36 @@ a <= nil
>>  | ---
>>  | - error: '[string "return a <= nil "]:1: attempt to compare decimal with nil'
>>  | ...
>> +-- and with box.NULL
>> +--
>> +a == box.NULL
>> + | ---
>> + | - false
>> + | ...
>> +a ~= box.NULL
>> + | ---
>> + | - true
>> + | ...
>> +a > box.NULL
>> + | ---
>> + | - error: '[string "return a > box.NULL "]:1: expected decimal, number or string as
>> + |     1 argument'
>> + | ...
> 
> 1 argument?

1st argument

> 
>> +a < box.NULL
>> + | ---
>> + | - error: '[string "return a < box.NULL "]:1: expected decimal, number or string as
>> + |     2 argument'
>> + | ...
> 
> 2 argument?

2nd argument

> 
> Why does the error message differ for the two seemingly equivalent
> cases? What's "1 argument"?
> 
> Note, in case of comparison with nil the error message is different:
> 
> | - error: '[string "return a > nil "]:1: attempt to compare decimal with nil'
> | - error: '[string "return a < nil "]:1: attempt to compare decimal with nil’

When you say ‘5 < nil’ you get an error ‘attempt to compare number with nil’
However, when you say ‘5 < box.NULL’ you get attempt to compare number
with ‘void *’.

So I tried to be consistent. Kind of. And just leave the message as it is.
We can say ‘attempt to compare decimal with box.NULL`
or with `void *` if you wish.

--
Serge Petrenko
sergepetrenko@tarantool.org



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Re: [tarantool-patches] Re: [PATCH] lua: fix decimal comparison with box.NULL

[Vladimir Davydov]

On Tue, Aug 27, 2019 at 03:10:47PM +0300, Serge Petrenko wrote:
> 
> > 27 авг. 2019 г., в 15:04, Vladimir Davydov <vdavydov.dev@gmail.com> написал(а):
> > 
> > On Tue, Aug 27, 2019 at 02:22:09PM +0300, Serge Petrenko wrote:
> >> This problem is similar to the one fixed in commit
> >> 3c6c1cc96a1a510493c21c472565d4063e403ba2 (lua:fix decimal comparison
> >> with nil)
> >> We should handle box.NULL the same way.
> >> 
> >> Closes #4454
> >> ---
> >> https://github.com/tarantool/tarantool/issues/4454
> >> https://github.com/tarantool/tarantool/tree/sp/gh-4454-decimal-cmp-null
> >> 
> >> src/lua/decimal.c         |  3 ++-
> >> test/app/decimal.result   | 30 ++++++++++++++++++++++++++++++
> >> test/app/decimal.test.lua |  8 ++++++++
> >> 3 files changed, 40 insertions(+), 1 deletion(-)
> >> 
> >> diff --git a/src/lua/decimal.c b/src/lua/decimal.c
> >> index 23e50ba68..8905a0b9d 100644
> >> --- a/src/lua/decimal.c
> >> +++ b/src/lua/decimal.c
> >> @@ -235,7 +235,8 @@ static int
> >> ldecimal_eq(struct lua_State *L)
> >> {
> >> 	assert(lua_gettop(L) == 2);
> >> -	if (lua_isnil(L, 1) || lua_isnil(L, 2)) {
> >> +	if (lua_isnil(L, 1) || lua_isnil(L, 2) ||
> >> +	    luaL_isnull(L, 1) || luaL_isnull(L, 2)) {
> >> 		lua_pushboolean(L, false);
> >> 		return 1;
> >> 	}
> >> diff --git a/test/app/decimal.result b/test/app/decimal.result
> >> index 8251e13d8..90d0984b0 100644
> >> --- a/test/app/decimal.result
> >> +++ b/test/app/decimal.result
> >> @@ -248,6 +248,36 @@ a <= nil
> >>  | ---
> >>  | - error: '[string "return a <= nil "]:1: attempt to compare decimal with nil'
> >>  | ...
> >> +-- and with box.NULL
> >> +--
> >> +a == box.NULL
> >> + | ---
> >> + | - false
> >> + | ...
> >> +a ~= box.NULL
> >> + | ---
> >> + | - true
> >> + | ...
> >> +a > box.NULL
> >> + | ---
> >> + | - error: '[string "return a > box.NULL "]:1: expected decimal, number or string as
> >> + |     1 argument'
> >> + | ...
> > 
> > 1 argument?
> 
> 1st argument
> 
> > 
> >> +a < box.NULL
> >> + | ---
> >> + | - error: '[string "return a < box.NULL "]:1: expected decimal, number or string as
> >> + |     2 argument'
> >> + | ...
> > 
> > 2 argument?
> 
> 2nd argument

But in both cases box.NULL is the second argument, isn't it?

Anyway, looks like it's a different issue, because I get the same
confusing error message while trying to compare a decimal with, say,
a string. We can fix it in a separate patch if we need to.

Pushed the patch to the master branch as is.

Re: [tarantool-patches] Re: [PATCH] lua: fix decimal comparison with box.NULL

[Serge Petrenko]

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> 27 авг. 2019 г., в 15:25, Vladimir Davydov <vdavydov.dev@gmail.com> написал(а):
> 
> On Tue, Aug 27, 2019 at 03:10:47PM +0300, Serge Petrenko wrote:
>> 
>>> 27 авг. 2019 г., в 15:04, Vladimir Davydov <vdavydov.dev@gmail.com> написал(а):
>>> 
>>> On Tue, Aug 27, 2019 at 02:22:09PM +0300, Serge Petrenko wrote:
>>>> This problem is similar to the one fixed in commit
>>>> 3c6c1cc96a1a510493c21c472565d4063e403ba2 (lua:fix decimal comparison
>>>> with nil)
>>>> We should handle box.NULL the same way.
>>>> 
>>>> Closes #4454
>>>> ---
>>>> https://github.com/tarantool/tarantool/issues/4454
>>>> https://github.com/tarantool/tarantool/tree/sp/gh-4454-decimal-cmp-null
>>>> 
>>>> src/lua/decimal.c         |  3 ++-
>>>> test/app/decimal.result   | 30 ++++++++++++++++++++++++++++++
>>>> test/app/decimal.test.lua |  8 ++++++++
>>>> 3 files changed, 40 insertions(+), 1 deletion(-)
>>>> 
>>>> diff --git a/src/lua/decimal.c b/src/lua/decimal.c
>>>> index 23e50ba68..8905a0b9d 100644
>>>> --- a/src/lua/decimal.c
>>>> +++ b/src/lua/decimal.c
>>>> @@ -235,7 +235,8 @@ static int
>>>> ldecimal_eq(struct lua_State *L)
>>>> {
>>>> 	assert(lua_gettop(L) == 2);
>>>> -	if (lua_isnil(L, 1) || lua_isnil(L, 2)) {
>>>> +	if (lua_isnil(L, 1) || lua_isnil(L, 2) ||
>>>> +	    luaL_isnull(L, 1) || luaL_isnull(L, 2)) {
>>>> 		lua_pushboolean(L, false);
>>>> 		return 1;
>>>> 	}
>>>> diff --git a/test/app/decimal.result b/test/app/decimal.result
>>>> index 8251e13d8..90d0984b0 100644
>>>> --- a/test/app/decimal.result
>>>> +++ b/test/app/decimal.result
>>>> @@ -248,6 +248,36 @@ a <= nil
>>>> | ---
>>>> | - error: '[string "return a <= nil "]:1: attempt to compare decimal with nil'
>>>> | ...
>>>> +-- and with box.NULL
>>>> +--
>>>> +a == box.NULL
>>>> + | ---
>>>> + | - false
>>>> + | ...
>>>> +a ~= box.NULL
>>>> + | ---
>>>> + | - true
>>>> + | ...
>>>> +a > box.NULL
>>>> + | ---
>>>> + | - error: '[string "return a > box.NULL "]:1: expected decimal, number or string as
>>>> + |     1 argument'
>>>> + | ...
>>> 
>>> 1 argument?
>> 
>> 1st argument
>> 
>>> 
>>>> +a < box.NULL
>>>> + | ---
>>>> + | - error: '[string "return a < box.NULL "]:1: expected decimal, number or string as
>>>> + |     2 argument'
>>>> + | ...
>>> 
>>> 2 argument?
>> 
>> 2nd argument
> 
> But in both cases box.NULL is the second argument, isn't it?
> 
> Anyway, looks like it's a different issue, because I get the same
> confusing error message while trying to compare a decimal with, say,
> a string. We can fix it in a separate patch if we need to.

Ah, I see. Sorry for the misunderstanding.
Yes, here’s the reason for it:
(an extract from https://www.lua.org/manual/5.1/manual.html <https://www.lua.org/manual/5.1/manual.html>)
`a >= b is equivalent to b <= a. Note that, in the absence of a "le" metamethod, Lua tries the "lt", assuming that a <= b is equivalent to not (b < a).`
`a > b is equivalent to b < a.`

So, a > box.NULL actually calls `decimal_lt(box.NULL, a)`. That’s why argument numbers get messed up.
AFAIR you don’t have `__gt` and `__ge` metamethods in lua. I guess we should just get rid of argument numbers,
in error messages here, because I don’t see how this can be fixed otherwise.

> 
> Pushed the patch to the master branch as is.

Thanks!


--
Serge Petrenko
sergepetrenko@tarantool.org



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