Re: constexpr keyword is unnecessary

On 20/10/2024 20:28, Keith Thompson wrote:

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

I know there are compilers that don't support VLAs at all - that's
fair enough (and that's why I specifically mentioned it).  We can
expect that compilers that can't handle VLAs at all will not support
C23 constexpr, or any suggested C++ style extensions to the semantics
of "const".

 Why would we expect that?
 IIRC, Microsoft has decided not to support VLAs in its C compiler.  If
they chose not to support constexpr, they could not claim C23 conformance.
 

MS is in a somewhat different position than other C compiler vendors. They decided - for various reasons - not to support C99 other than parts that had direct correspondence with C++ features.  Without having followed any of the proceedings, I suspect the reason VLAs are optional in C23 is because MS wants to avoid adding more than they have to before being able to jump to (approximate) C23 conformance.  "constexpr" will be relatively easy for them, as they have it in C++ already.
(I don't know how recently updated the cppreference page on C23 compiler support is, but if it is accurate, MS has a long way to go before C23 conformance - if that is even their aim.)
Pretty much every other C compiler that aims for at least vague conformance, AFAIK, has done so linearly through the standards versions.