RFR: 8343580: Type error with inner classes of generic classes in functions generic by outer [v2]

[Aggelos Biboudis]

> javac determines erroneously that `getter` has a raw type (`G.Getter`). The type of `getter` is deduced as the raw type `Getters<T>.Getter` by javac. Thus, the `Object` in the following example. The question is whether it should be treated as raw or not in the scenario where the qualifying type *is* a type parameter, as in `G.Getter`. In this case `Getter` is inherited from the supertype `Getters<T>`:
> 
> 
> static abstract class Getters<T> {
>     abstract class Getter {
>         abstract T get();
>     }
> }
> 
> static class Usage<T, G extends Getters<T>> {
>     public T test(G.Getter getter) {
>         return getter.get(); // incompatible types: Object cannot be converted to T
>     }
> }
> 
> 
> It seems that this is a compiler bug. According to 4.8 Raw Types a “rare” type occurs when the inner is a partially raw type but the definition of Getter doesn’t take any type variables, so this is not a case of a "rare" type. `G.Getter` describes a type with a qualifying type being a type parameter which is not raw and moreover there is an instantiation of its bound. Simply not looking into the bounds of `G` seems like a compiler bug.

Aggelos Biboudis has updated the pull request incrementally with one additional commit since the last revision:

  Address review

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/25346/files
  - new: https://git.openjdk.org/jdk/pull/25346/files/d2d59f9a..e228c004

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25346&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25346&range=00-01

  Stats: 22 lines in 2 files changed: 19 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/25346.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25346/head:pull/25346

PR: https://git.openjdk.org/jdk/pull/25346