[erlang-bugs] Parser bug: if missing ", " in list between records, the first is ignored, and no parser warnings are given.

[Mattias Waldau]

Yes, I can agree that

#rec{a=2}#rec{b=3}

is a matter of opinion. However, I completely fail to understand how

#rec{a=2}#rec{a=3}

can be a matter of opinion, since data in the code is LOST.

There should be a warning. My sample below shows how catastropic the missing "," can be.

/mattias

On 07/11/2014 13:22, Roland Karlsson wrote:
> Maybe we shall not discuss this for ever :)
> It is a matter of opinion after all.
>
> But - it is the same IMHO. It is a matter of operators and the need
> to set paranthesis when the precedents and right/left association is
> not obvious.
>
> The rec example can be written thus
>
> (#rec{a=2})#rec{b=3}
>
> Then everything is clear.
>
>
> /Roland
>
>
>
>> I'm not sure how that relates. This expression can be reasonably written
>> on purpose. The same cannot be said for #rec{a=2}#rec{b=3}.
>>
>> On 11/07/2014 02:01 PM, Roland Karlsson wrote:
>>> If there is a warning there, then all expressions including operators,
>>> e.g. arithmetic, should have warnings. How about 10 + 1 rem 3 + 7. ?
>>> Do you know the precedence of + and rem ? What is the result?
>>>
>>> /Roland
>>>
>>>
>>>
>>>> Warnings are ordinary Erlang code which is prone to errors.
>>>>
>>>> On 11/07/2014 01:46 PM, Roland Karlsson wrote:
>>>>> No warning is needed methinks. It is just ordinary Erlang code.
>>>>> It is equal to.
>>>>>
>>>>>> REC1 = #rec{b=3}.
>>>>>> REC2 = REC1#rec{a=2}.
>>>>> Nothing strange at all.
>>>>>
>>>>>
>>>>> /Roland
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> It is legal but there probably should be a warning for this
>>>>>> particular
>>>>>> case. I cannot think of a valid reason to do #rec{a=2}#rec{b=3} when
>>>>>> you
>>>>>> can just do #rec{a=2, b=3}.
>>>>>>
>>>>>> On 11/07/2014 10:09 AM, Vlad Dumitrescu wrote:
>>>>>>> Hi Mattias,
>>>>>>>
>>>>>>> This isn't a bug. The expression #rec{a=2}#rec{b=3} is legal, and is
>>>>>>> the
>>>>>>> same thing as (#rec{a=2})#rec{b=3} or #rec{a=2,b=3}. If the keys
>>>>>>> overlap, then the last one "wins".
>>>>>>>
>>>>>>> best regards,
>>>>>>> Vlad
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Nov 6, 2014 at 9:21 AM, Mattias Waldau
>>>>>>> <mattias.waldau@REDACTED <mailto:mattias.waldau@REDACTED>>
>>>>>>> wrote:
>>>>>>>
>>>>>>>        This is the program
>>>>>>>
>>>>>>>        -module('missing-comma-not-detected').
>>>>>>>
>>>>>>>        -export([data/1]).
>>>>>>>
>>>>>>>        -compile(export_all).
>>>>>>>
>>>>>>>        -record(shcnode, {
>>>>>>>               nodename :: any(),
>>>>>>>               y_axis :: number(),
>>>>>>>               children :: [any()],
>>>>>>>               article_number :: number(),
>>>>>>>               attribute_condition :: string()}).
>>>>>>>
>>>>>>>
>>>>>>>        data(1) ->
>>>>>>>             [
>>>>>>>              #shcnode{nodename = start, y_axis = 0, children =
>>>>>>> [d1285]},
>>>>>>>              #shcnode{nodename = d1285, y_axis = 295, children =
>>>>>>> [1939,
>>>>>>> 1940]}
>>>>>>>              #shcnode{nodename = 1940, y_axis = 525, children =
>>>>>>> [bm3203],
>>>>>>>        article_number = 14432861},
>>>>>>>              #shcnode{nodename = 1939, y_axis = 530, children =
>>>>>>> [bm3203],
>>>>>>>        article_number = 14432860},
>>>>>>>              #shcnode{nodename = bm3203, y_axis = 915, children = []}
>>>>>>>             ].
>>>>>>>
>>>>>>>
>>>>>>>        Note the missing "," after  [1939, 1940]}
>>>>>>>
>>>>>>>        Only 4 rows are detected
>>>>>>>
>>>>>>>        length('missing-comma-not-detected':data(1)).
>>>>>>>        4
>>>>>>>
>>>>>>>        ---
>>>>>>>
>>>>>>>        If I add the comma, I get
>>>>>>>
>>>>>>>        length('missing-comma-not-detected':data(1)).
>>>>>>>        5
>>>>>>>
>>>>>>>        ----
>>>>>>>
>>>>>>>        I am using Erlang 17.3 on ubuntu.
>>>>>>>
>>>>>>>        erlang:system_info(otp_release).
>>>>>>>        "17"
>>>>>>>
>>>>>>>        36> |erl -V
>>>>>>>        Eshell V6.2  (abort with ^G)
>>>>>>>        1> |
>>>>>>>
>>>>>>>        ---
>>>>>>>
>>>>>>>        Thanks,
>>>>>>>
>>>>>>>        Mattias
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>        _______________________________________________
>>>>>>>        erlang-bugs mailing list
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>>>>>>>        http://erlang.org/mailman/listinfo/erlang-bugs
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> erlang-bugs mailing list
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>>>>>>> http://erlang.org/mailman/listinfo/erlang-bugs
>>>>>>>
>>>>>> --
>>>>>> Loïc Hoguin
>>>>>> http://ninenines.eu
>>>>>> _______________________________________________
>>>>>> erlang-bugs mailing list
>>>>>> erlang-bugs@REDACTED
>>>>>> http://erlang.org/mailman/listinfo/erlang-bugs
>>>>>>
>>>>>
>>>> --
>>>> Loïc Hoguin
>>>> http://ninenines.eu
>>>>
>>>
>> --
>> Loïc Hoguin
>> http://ninenines.eu
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