class grammar

[Basile B.]

On Friday, 7 May 2021 at 18:07:45 UTC, Nick wrote:
> The class grammar, as defined in the D language specification 
> ...
> is not clear to me how a user-defined type (such as a class or 
> interface) is also a 'BasicType' (as defined by the grammar). 
> However, the compiler only accepts classes or interfaces as a 
> base type.
>

Just like a natural language what is grammatically correct is not 
necessarily semantically correct.

In the case of the inherithence list it's easier to choose 
'BasicType' because 'TypeOf' and 'QualifiedIdentifier' can both 
be solved to a class or an interface.

With this example:

```
alias B = int;
class A : B {}
```

you can see that the semantic check to reject `int` is necessary 
anyway.