Re: Results of survey re. a new array size operator

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

On 29/01/2025 17:00, Ben Bacarisse wrote:

Alexis <flexibeast@gmail.com> writes:
 

JeanHeyd Meneide, a Project Editor for WG14, has just posted the results
of a survey re. the preferred form of a new array size operator:
>
-- https://thephd.dev/the-big-array-size-survey-for-c-results

Curious.  The top objection to the usual macro solution is given as:
   * double-evaluation of e.g. getting the size of the 1-d part of a 2-d
     array int meow[3][4]; /* ... */ SIZE_KEYWORD(meow[first_idx()]);
Does the author not know that there is no evaluation of the operands of
sizeof in this example?
 

>
6.5.3.4p2 :
>
"""
If the type of the operand is a variable length array type, the operand is
evaluated; otherwise, the operand is not evaluated and the result is an
integer constant.
"""
>
I don't know if that is the source of the double-evaluation concern here,
but it is certainly a situation in which sizeof /does/ evaluate its
operand.

It would have been a good idea to pick an example that behaves as
claimed.  Let's hope this sort of casual approach is reserved for blogs.

--
Ben.