bug: Use of generic within implicit parselet fails to compile

[phorward]

This little program

Test : @<T: 'x'> {
    Pos<(T | 'X')>
}

Test

fails to compile:

thread 'main' panicked at src/compiler/iml/imlvalue.rs:355:52:
IndexMap: key not found
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

The problem is that (T | 'X') is made into an implicit parselet, which references generic T, but T is not a generic of that implicit parselet. Unfortuntately, this issue is a conceptual problem with the current compiler. It cannot be bypassed right now.

[phorward]

The problem can be seen as part of #128

[phorward]

Here are further examples that all produce invalid results. It is a design issue in the compiler's current ImlParselet concept, which requires a deeper and stable rewrite. Tested with Tokay v0.6.6 (a245f24)

Fails with thread 'main' panicked at src/compiler/iml/imlparselet.rs:244:63: called Option::unwrap() on a None value

Double : @<U> {
    print("Double   ->", *U)
    U U
}

Single : @<V> {
    print("Single   ->", *V)
    V | 'X'
}

Test : @<T: 'x'> {
    print("Test     ->", *T)
    Double<Single<T>>  print("YES")
}

---

This version where all generics are named T "runs", but it produces invalid results and is not the wanted behavior.

Double : @<T> {
    print("Double   ->", *T)
    T T
}

Single : @<T> {
    print("Single   ->", *T)
    T | 'X'
}

Test : @<T: 'x'> {
    print("Test     ->", *T)
    Double<Single<T>>  print("YES")
}

Test

So this is an example that must work in both cases and should accept the input xx, XX, xX and Xx with YES printed.

Unfortunately I currently don't have the time to face this, but I will do ASAP and when I have an idea for an implementation. Help wanted!