What would break if class was merged with struct

[Ola Fosheim Grøstad via Digitalmars-d]

On Saturday, 27 May 2017 at 18:06:11 UTC, Stanislav Blinov wrote:
> Perhaps it wouldn't be if we were talking about new language.
> With D, such a change falls out of "some language changes, a 
> bit of automated source updating and a little bit of breakage", 
> and becomes "whole language change, a rewrite of runtime and 
> standard library, and breaking every single project that uses D 
> today".
> Or did we leave behind your original question?

No. I am talking about language semantics. Are the semantics for 
class and struct conflicting or can they be merged?

That is the question.

I am talking about the language, as specified, not the 
implementation.

> Yes.

Huhhh?? :^)

> :) Everything is an "implementation detail".

No... No... No...