Wouldn't this be better with bitfields?

[Richard (Rikki) Andrew Cattermole]

On 04/07/2024 1:47 PM, Steven Schveighoffer wrote:
> On Wednesday, 3 July 2024 at 17:58:53 UTC, Walter Bright wrote:
>> On 7/2/2024 8:26 PM, Steven Schveighoffer wrote:
>>> Is there a guarantee that the bit pattern will match what the CPU 
>>> expects?
>>
>> As I've written many times, if you stick with uint the layout is 
>> portable with every C compiler I know of.
> 
> So my response was mostly tongue in cheek, since the dismissal of 
> previous concerns about exact layout was always "just use std.bitmanip". 
> I have since relented that I'm OK with the C compatibility as long as 
> there is some expectation that "as long as you use uint, it's fine".
> 
> But... I'm thinking now, why not just specify that? If you use uint, 
> this is the explicit layout, and any C compiler that doesn't implement 
> that mechanism, D does not support bitfield compatibility.
> 
> That would go a long way to alleviating any concerns that portability 
> would be based on the whim of some C compiler.
> 
> This should be fine, because, as you say, everyone already does it that 
> way. D has the opportunity to make this official.
> 
> -Steve

As a consequence it does mean that you shouldn't be doing things like 
tagged pointers with it.

And that's a problem since pretty much all new cpu designs are 64bit.