How to represent Base_type expansion

[GorNishanov]

Consider:

template <typename... T>
struct X : T... {};

This is not representable in IPR at the moment.
Expansion operates on Classic expressions. Base_type is a declaration and bases are Sequence<Base_type>.

This issue will interplay with #65

[GabrielDosReis]

Base_type takes the type to be used as base type as argument -- see also Class::declare_base().

In your example, T... is an expansion, so you get the expression Expansion [operand: As_type [expr: T]], which can you can now use as operand to As_type to get a type used as base type. E.g.

Base_type [base: 
   As_type [expr: 
       Expansion [operand: 
           As_type [expr: T]
       ]
   ]
]

Which part is not representable in IPR at the moment?

[GorNishanov]

This would be possible if Expansion would take an Expr as an operand.
At the moment, it is limited to just Classic expressions. As_type is not a Classic expression

[GabrielDosReis]

This would be possible if Expansion would take an Expr as an operand.

The definition of Expansion says that it is a Classic unary structure that takes a general Expr as operand.

   struct Expansion : Unary<Category<Category_code::Expansion, Classic>> { };

The factory function make_expansion() takes a const ipr::Expr&

Am I reading that wrong?

[GorNishanov]

Yes. You are right. I was reading the definition wrong :-)