Hello Jens,
On Thu, Aug 08, 2024 at 07:35:12AM GMT, Jₑₙₛ Gustedt wrote:
> Hello Alejandro,
>
> On Thu, 8 Aug 2024 00:44:02 +0200, Alejandro Colomar wrote:
>
> > +Its syntax is similar to @code{sizeof}.
>
> For my curiosity, do you also make the same distinction that with
> expressions you may omit the parenthesis?I thought of it. TBH, I haven't tested that thoroughly. In principle, I have implemented it in the same way as sizeof, yes. Personally, I would have never allowed sizeof without parentheses, but I understand there are people who think the parentheses hurt readability, so I kept it in the same way. I'm not sure why the parentheses are necessary with type names in sizeof, but to maintain expectations, I think it would be better to do the same here. > > I wouldn't be sure that we should continue that distinction from > `sizeof`. But then, what do we do? Allow lengthof with type names without parens? Or require parens? I'm not comfortable with that choice. > Also that prefix variant would be difficult to wrap in a > `lengthof` macro (without underscores) as we would probably like to > have it in the end. Do you mean that I should add _Lengthof? We're adding __lengthof__ to be a GNU extension with relative freedom from ISO. If I sent a patch adding _Lengthof, we'd have to send a proposal to ISO at the same time, and we'd be waiting for ISO to discuss it before I can merge it. And we couldn't bring prior art to ISO. With this approach instead, the plan is: - Merge __lengthof__ in GCC before ISO hears of it (well, there are already several WG14 members in this discussion, so you have actually heard of it, but we're free to do more or less what we want). - Propose _Lengthof to ISO C, with prior art in GCC as __lengthof__, proposing the same semantics. Also propose a lengthof macro defined in <stdlength.h> - When ISO C accepts _Lengthof and lengthof, map _Lengthof in GCC to the same internals as __lengthof__, so they are the same thing. Still, I'm interested in having some feedback from WG14, to prevent implementing something that will have modifications when merged to ISO C, so please CC anyone interested from WG14, if you know of any. Have a lovely day! Alex -- <https://www.alejandro-colomar.es/>
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