[code-reflection] RFR: Improve JavaType::toString

[Paul Sandoz]

On Fri, 31 May 2024 21:00:04 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> The string representation of `JavaType` is automatically derived from the type's externalized form. This PR tweaks the implementation of `toString` so that a more meaningful representation is generated, namely one that is consistent with `java.lang.reflect.Type::getTypeName`.
> 
> For instance, instead of this:
> 
> 
>  .<Outer<java.lang.String>, Outer$Inner<java.lang.Integer>>
> 
> 
> This is now generated:
> 
> 
> Outer<java.lang.String>$Inner<java.lang.Integer>
> 
> 
> I've added another combinatorial test which checks that `Type::getTypeName` of the resolved reflective type matches the string representation of the original `JavaType`.
> 
> The main question is around `ClassType::toClassName`. This method is effectively attempting to generate a user-friendly type string from the `JavaType` (note that this method doesn't take into account enclosing types). Should we update this to call `toString` ? Or should we perhaps remove it, and ask clients to use `toString` instead (which now works on all types) ?

Alignment with `Type.toString` is very useful for runtime debugging. I think we should remove `ClassType.toClassName`. We should probably rename the `JavaType.ofString` method to avoid confusion.

It occurred to me that the externalized form of a qualified class does not have to duplicate if that helps debugging via code models, we could have:


.<Outer<java.lang.String>, Inner<java.lang.Integer>>


Or even:


$<Outer<java.lang.String>, Inner<java.lang.Integer>>

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Marked as reviewed by psandoz (Lead).

PR Review: https://git.openjdk.org/babylon/pull/110#pullrequestreview-2091772849