Would love to override default ctor of struct

[Alex]

On Monday, 21 January 2019 at 20:50:45 UTC, Meta wrote:
> On Monday, 21 January 2019 at 19:08:49 UTC, Alex wrote:
>> Could you give an example, where a zero argument construction 
>> has to be done, which cannot be accomplished by setting the 
>> appropriate field with a default value?
>
> For the following reason, although the default argument 
> constructor hack no longer works:
> [...]

Ok, and I'm wondering what of this initialization cannot be done 
without a constructor?