Groups > comp.lang.c > #161956

Re: Array is an non-modifiable lvalue - where does it matter?

From	Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups	comp.lang.c
Subject	Re: Array is an non-modifiable lvalue - where does it matter?
Date	2021-07-18 02:09 +0100
Organization	A noiseless patient Spider
Message-ID	<87im18mnqr.fsf@bsb.me.uk> (permalink)
References	<scq5c5$tql$1@dont-email.me> <20210716145835.570@kylheku.com> <sctt7r$88g$1@dont-email.me>

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Andrey Tarasevich <andreytarasevich@hotmail.com> writes:

> On 7/16/2021 3:21 PM, Kaz Kylheku wrote:
>> If what you are getting at is this: could a C dialect provide complete
>> support for array passing, returning and assignment, while conforming
>> to the current standard?
>> The answer is no.
>
> No, no, no, I'm not interested in that at all.
>
>>> Am I right here? Is the constraint of 6.5.16/2 supposed to be applied
>>> before automatic implicit conversions or after them?
>> It looks moot. Before conversion to pointer, you have an array lvalue,
>> and the requirement says that it' not modifiable. Thus, cannot assign to
>> it. After conversion to pointer, you don't have an lvalue. Not
>> assignable, either.
>> 
>
> Yes, it is moot for the specific case of arrays.
>
> But at the same time it intuitively looks and feels like a more
> general issue. Again, what comes first: automatic implicit conversions
> or constraint checks?

That the /intent/ is that the constraints apply after these conversions
is obvious from many other common situations.  For example, given

  int array[2];
  void f(void);

both *array and f() would be constraint violations unless the
conversions in section 6.3.2.1 are applied first.

> And even if this currently proves to be moot in all other contexts as
> well, it still appears to be something kinda... too important to be
> left unspecified.

Is it clearly specified?  I don't know.  I've never thought it could be
taken any other way, but the fact that you were not sure makes this
obviously wrong.

-- 
Ben.

Thread

Array is an non-modifiable lvalue - where does it matter? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-15 13:21 -0700
  Re: Array is an non-modifiable lvalue - where does it matter? Öö Tiib <ootiib@hot.ee> - 2021-07-15 13:55 -0700
    Re: Array is an non-modifiable lvalue - where does it matter? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-15 22:12 +0100
      Re: Array is an non-modifiable lvalue - where does it matter? Öö Tiib <ootiib@hot.ee> - 2021-07-15 15:07 -0700
        Re: Array is an non-modifiable lvalue - where does it matter? David Brown <david.brown@hesbynett.no> - 2021-07-16 09:52 +0200
          Re: Array is an non-modifiable lvalue - where does it matter? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-07-16 02:31 -0700
          Re: Array is an non-modifiable lvalue - where does it matter? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-16 10:59 -0700
            Re: Array is an non-modifiable lvalue - where does it matter? David Brown <david.brown@hesbynett.no> - 2021-07-17 16:23 +0200
              Re: Array is an non-modifiable lvalue - where does it matter? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-07-17 20:14 -0400
    Re: Array is an non-modifiable lvalue - where does it matter? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-15 14:36 -0700
      Re: Array is an non-modifiable lvalue - where does it matter? Öö Tiib <ootiib@hot.ee> - 2021-07-15 15:19 -0700
  Re: Array is an non-modifiable lvalue - where does it matter? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-07-15 14:06 -0700
  Re: Array is an non-modifiable lvalue - where does it matter? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-07-16 14:22 -0400
    Re: Array is an non-modifiable lvalue - where does it matter? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-16 11:43 -0700
      Re: Array is an non-modifiable lvalue - where does it matter? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-17 18:24 -0700
        Re: Array is an non-modifiable lvalue - where does it matter? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-07-17 20:29 -0700
        Re: Array is an non-modifiable lvalue - where does it matter? Siri Cruise <chine.bleu@yahoo.com> - 2021-07-17 21:25 -0700
    Re: Array is an non-modifiable lvalue - where does it matter? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-07-16 15:22 -0700
  Re: Array is an non-modifiable lvalue - where does it matter? Kaz Kylheku <563-365-8930@kylheku.com> - 2021-07-16 22:21 +0000
    Re: Array is an non-modifiable lvalue - where does it matter? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-16 23:27 -0700
      Re: Array is an non-modifiable lvalue - where does it matter? Kaz Kylheku <563-365-8930@kylheku.com> - 2021-07-17 16:53 +0000
        Re: Array is an non-modifiable lvalue - where does it matter? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-17 10:49 -0700
        Re: Array is an non-modifiable lvalue - where does it matter? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-07-17 14:01 -0700
      Re: Array is an non-modifiable lvalue - where does it matter? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-18 02:09 +0100
    Re: Array is an non-modifiable lvalue - where does it matter? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-07-17 20:12 -0400
  Re: Array is an non-modifiable lvalue - where does it matter? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-07-17 13:20 -0700
    Re: Array is an non-modifiable lvalue - where does it matter? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-19 14:44 -0700
      Re: Array is an non-modifiable lvalue - where does it matter? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-07-23 23:26 -0700

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