Re: C23 thoughts and opinions

David Brown <david.brown@hesbynett.no> writes:

On 23/05/2024 00:53, Keith Thompson wrote:

[...]

I dislike the C++ hack of making N a constant expression given
`const int N = 42;`; constexpr made that unnecessary. 

>
I find that "hack" convenient at times.  But I see what you mean that
it is a "hack", and I agree that "constexpr" makes such a hack
unnecessary.   (Ideally, the languages would have used terms such as
"read_only" and "constant" rather than "const" and "constexpr", but
that boat sailed long ago.)
>

C23 makes the
same (IMHO) mistake.

>
I don't think so - as far as I can see, it avoids that mistake (if you
feel the "hack" was a mistake).  C23 can't fix the choice of names -
that was from C90.

Apparently I was mistaken.  I had thought that C23 made this legal (as
it is in C++):

#include <stdio.h>
int main(void) {
    const int n = 42;
    switch (n) case n: puts("ok");
}

There was a proposal to do this:
    https://thephd.dev/_vendor/future_cxx/papers/C%20-%20Initialized%20const%20Integer%20Declarations.html
and I wrote a response to it:
    https://github.com/Keith-S-Thompson/const-proposal-response
but the proposed wording does not appear in N3220.

(If you want n to be a constant expression, replace "const" with
"constexpr" -- or use a macro or the enum hack if you don't have a C23
compiler.)

We're definitely stuck with the "const" and "constexpr" keywords, but at
least the semantics of "const" are reasonably consistent.

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */