DIP 1051--"Add Bitfields to D"--Formal Assessment

[Jack Son]

On Tuesday, 10 June 2025 at 12:34:21 UTC, Mike Parker wrote:
> After discussions in multiple meetings, we finally reached a 
> point back in April where I could merge Walter's bitfields DIP 
> and submit it to Atila for the final decision.
>
> The DIP was accepted based on the following rationale.
>
> Bitfields are useful in the following cases:
>
> 1. minimizing memory consumption in a struct;
> 2. creating binary-compatible data structures between D and C 
> or C++;
> 3. conforming a struct layout to external requirements, such as 
> a hardware register.
>
> This DIP adopts the C and C++ syntax because of its simplicity. 
> A persistent objection to the proposal was that C's bitfield 
> layout is implementation defined. Proposals to implement a 
> D-portable layout and special-case the C-defined layout 
> suffered from unattractive syntax, so were not adopted.
>
> In practice, layouts are consistent on each platform, but can 
> vary between platforms. This is irrelevant for Cases 1 and 2. 
> For Case 3, in the rare cases where the layout may become a 
> problem, it is easy to work around by specifying a bitfield to 
> match any layout, and by employing shifting and masking as 
> necessary.
>
> This is a purely additive feature that should break no existing 
> code.
>
> https://github.com/dlang/DIPs/blob/master/DIPs/accepted/DIP1051.md http://flappydunk.io

Great to see this finalized and accepted—bitfields will 
definitely help with tighter memory control and interoperability. 
Thanks for pushing it through!