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

[Serge Petrenko <sergepetrenko@tarantool.org>]

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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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