Question? How to extract type parameters from this case

[jasonkuhrt]

In this case the type of Foo becomes interned to Qux<1, 2> & 2. This type is seen as an intersection. Its getText() returns Bar<1,2>. Its symbol name is Bar. Its getTargetType returns undefined.

    type Qux<A, B> = {}
    type Bar<A, B> = Qux<A, B> & B
    export type Foo = Bar<1, 2>

My question is this, then... How can we write logic to extract type parameters?

The logic I had before was:

1. If getTargetType returns another type then try extracting type arguments from self via getTypeArguments
2. otherwise for aliases, classes, interfaces try extracting type parameters via getTypeArguments

The idea that I could identify the generic type by checking t.getTargetType() === t turns out to not always hold. For example here Qux<A,B> object type returns undefined for t.getTargetType().

The problem then is that I am in a situation where I can't tell the difference between Foo<1, 2> (should extract type arguments) and Qux<A, B> (should extract type parameters).

... I am probably doing something wrong, but I can't tell what it is. I'm posting here on the off chance that ts-morph has a missing feature or bug.

[jasonkuhrt]

https://stackoverflow.com/questions/65376601/how-to-extract-type-parameters-from-type-alias-type-arguments-from-generic-ins

[jasonkuhrt]

When:

export type Foo = Bar<1, 2>

Gets interned to:

export type Foo = Qux<1, 2> & 2 // getText = Bar<1, 2>    |    type args = 1, 2

I could use the fact of type args 1, 2 to know that this intersection type is an instance of a generic with two type params. But I wouldn't know anything about the constraints, defaults, names, or ones with defaults that were not given type args.

So this doesn't work out as a solution.