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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c++
Subject: Re: C++20 concepts rocks
Date: Mon, 14 Feb 2022 23:55:17 -0800
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Ben Bacarisse <ben.usenet@bsb.me.uk> writes:

> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:

[edited for brevity]

>> If we have this code fragment
>>
>>     int foo[10][20];
>>     extern void set_elements( int *, size_t, int )
>>
>>     set_elements( (int*) &foo, 10*20, -1 );
>>
>> an argument could be made that set_elements() cannot use pointer
>> arithmetic (including that implied by use of []) on its first
>> argument other than to access between foo[0][0] and foo[0][19] (or
>> to construct a pointer to foo[0][20]).  [...]
>
> [...] It's what direct additions and subtractions are permitted
> for any given pointer that I no longer feel sure about.  Your "a
> case could be made" suggests you are not entirely sure either,
> though it does suggest you consider that case is a stretch.

The implied question here has a somewhat longish answer.  I'll
get to it when I can.  Also, as it seems we have drifted rather
far from C++, comp.std.c is I think a better place to continue.