On Thu, 30 Oct 2025 at 15:50, Arthur O'Dwyer via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> On Thu, Oct 30, 2025 at 10:59 AM Alejandro Colomar via Std-Proposals <
> std-proposals_at_[hidden]> wrote:
>
>> On Thu, Oct 30, 2025 at 07:27:38AM -0700, Thiago Macieira via
>> Std-Proposals wrote:
>> > On Wednesday, 29 October 2025 14:24:23 Pacific Daylight Time Thiago
>> Macieira
>> > via Std-Proposals wrote:
>> > > I disagree because I don't want to wait for that operation. I want
>> > > relocations now. In fact, I want them in 2005, when Qt began doing
>> them
>> > > anyway. It's memcpy/memmove, period.
>> >
>> > Oh, and realloc(). That's actually the most important one.
>> >
>> > I'll accept a replacement function if realloc() can't be fixed.
>>
>> I don't know if realloc(3) has any issues in C++, but if you mean the
>> issues that C also has, we're in the process of fixing them.
>> <https://www.austingroupbugs.net/view.php?id=1949>
>> <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3621.txt>
>>
>
> That seems to address only the "unhappiest path" where the caller is
> literally trying to do realloc(p, 0). Nobody does that in practice [he
> says, hyperbolically].
> I'm sure the API issues Thiago is talking about concern the "happy path."
> Things like:
>
> - Sometimes when I call `realloc`, the buffer doesn't move, and so
> pointers/iterators/references aren't invalidated. How can I tell when this
> happens? (In practice I think this is easy, but technically at least in C++
> it's UB even to read the *pointer value* of the old, freed pointer in
> order to equality-compare it with the new pointer.)
> - Sometimes when I call `malloc` or `realloc`, the returned buffer
> actually has more capacity than I asked for. How can I tell the true
> capacity of the buffer? <https://stackoverflow.com/a/48612539/1424877>
> - Sometimes when I call `malloc` or `realloc`, I'd *like* N bytes, but
> I'd be *satisfied* to fall back to M. How can I communicate this to the
> system?
> - Almost always when I call `malloc` or `realloc`, I care about the
> alignment of the buffer. How can I communicate my alignment requirement to
> the system? (There is still no aligned_realloc.)
> <https://stackoverflow.com/questions/56619623/why-is-there-no-aligned-realloc-on-most-platforms>
>
> Thiago may have been thinking of even more/different API issues, too.
>
>
All that, and it also just does too many things for a single API.

It can allocate new memory, free old memory, reallocate existing memory,
... why even bother having malloc and free, realloc can do it all!