Constructor called instead of opAssign()

[Boris Carvajal]

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.