Can now use alias for collapsing multiple fields in nested structs

[Nick Treleaven]

On Thursday, 2 January 2025 at 21:14:25 UTC, ryuukk_ wrote:
> On Thursday, 2 January 2025 at 19:08:06 UTC, Walter Bright 
> wrote:
>> On 1/2/2025 6:32 AM, Derek Fawcus wrote:
>>> The closest native equivalent in D, would seem to be the 
>>> following, making use of the new facility.
>>> 
>>> ```D
>>> struct outer {
>>>      int a;
>>>      struct inner_ {
>>>              int b;
>>>              int c;
>>>      }
>>>      inner_ inner;
>>>      int d;
>>>      alias b = inner.b;
>>>      alias c = inner.c;
>>> };
>>> ```
>>> 
>>> Or is there a nicer way to write that in D?
>>
>> ```
>> struct outer {
>>     int a;
>>     struct {
>>         int b;
>>         int c;
>>     }
>>     int d;
>> }
>> ```
>
> that's hard to learn, why is it possible to do `outter.b = 42`?

That's how it works in C11. The spec shows some useful use cases:

https://dlang.org/spec/struct.html#anonymous

> ```
> struct outer {
>     int a;
>     struct {
>         int b;
>         int c;
>     } inner;
>     int d;
> }
> ```
>
> now it is easier to learn, it is an anonymous struct called 
> `inner`

That complicates the parser, beginners would forget to type the 
`;` after a struct definition and get confused at the parse 
errors.

Why do you need an anonymous struct type there? Naming it and 
using the struct name for `inner` isn't difficult, and it doesn't 
seem needed that often.