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From: David Brown <david.brown@hesbynett.no>
Newsgroups: comp.lang.c
Subject: Re: constexpr keyword is unnecessary
Date: Sun, 20 Oct 2024 12:45:46 +0200
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On 19/10/2024 21:41, Thiago Adams wrote:
> Em 10/19/2024 1:03 PM, David Brown escreveu:
>> On 19/10/2024 17:18, Thiago Adams wrote:
>>> Em 10/18/2024 8:54 PM, Keith Thompson escreveu:
>>>> Thiago Adams <thiago.adams@gmail.com> writes:
>>>>> I think constexpr keyword is unnecessary.
>>>>
>>>> Sure, most language features are strictly unnecessary.
>>>>
>>>>> Anything you do with it could/should be done with const.
>>>>
>>>> No, absolutely not.
>>>>
>>>
>>> If not, do you have a sample where, using "const" as "constexpr", 
>>> would create problems?
>>>
>>> The sample I know is VLA.
>>>
>>> const int c = 2;
>>> int a[c]; //a is VLA because c is not a constant expression.
>>>
>>>
>>> But this is not enough to convince me because it is better not to be 
>>> a VLA here.
>>>
>>
>> What practical difference would it make? 
> 
> I don't see any practical difference. In theory, the generated code 
> could be different, but I'm arguing that this doesn't really matter and, 
> consequently, it's not a good reason to differentiate between const and 
> constexpr.
> 

My point was that if there is no practical difference, then there is no 
reason to object to the VLA.

You can't use this as a reason for arguing that it would have been 
better for "const" in C to gain the features that are now in C23 
"constexpr", because this use of "const" was already allowed in C99.  So 
the "const" vs "constexpr" discussion is an orthogonal issue - I was 
asking specifically about your comment regarding your apparent dislike 
of VLA's.