Support for properties in the parent type

Unassigned rule calls create a parent-child relation, and in the example below, AbstractToken is a parent of TokenA, TokenB and TokenC. AbstractToken also has own property cardinality.

AbstractToken:
  ( TokenA
  | TokenB
  | TokenC
  ) cardinality=('?'|'+'|'*')?;

However, types generation only reflects reflects ownership, not inheritance. Generated types:

export interface AbstractToken extends AstNode {
    cardinality?: '*' | '+' | '?'
}

// similar to `TokenB` and `TokenC`
export TokenA extends AstNode {
	...
}

Since inheritance is reflected by union type for the purpose of property lifting, we should generate the types in the above case as follows:

export type AbstractToken = (TokenA | TokenB | TokenC) & { cardinality?: '*' | '+' | '?' }

[pluralia]

We could simply decide not to do any property lifting ourselves here and see whether it’s a real problem in languages that have such constructs. WDYT?

Yes, that makes sense. At least we can take a pause to think more about it. I move the milestone.

[spoenemann]

we have to manually lift the children properties, and thus we go back to necessity to implement an algorithm that lifts properties.

@pluralia I think now I understood what you mean. But nobody forces us to do this lifting, it’s really just a convenience feature. We could simply decide not to do any property lifting ourselves here and see whether it’s a real problem in languages that have such constructs. WDYT?