Constructor called instead of opAssign()

[frame]

On Sunday, 14 February 2021 at 08:38:49 UTC, Boris Carvajal wrote:
> On Sunday, 14 February 2021 at 07:09:20 UTC, frame wrote:
>> Although x is well initialized by A by calling opAssign(), the 
>> compiler doesn't care and calls the S!T ctor() on B again and 
>> opAssign() is ignored. Is this a bug or a rule?
>
> It's a rule described here: 
> https://dlang.org/spec/struct.html#field-init
>
> "In a constructor body ... the first instance of field 
> assignment is its initialization."
>
> If you assign a second time, it will use the opAssign method.

The first instance is in A - and why opAssign then works there?