Fix: Make sure compact constructor assignments resolve correctly to the fields

[Luro02]

While updating my code to newer spoon versions, I observed that in code like:

record MyRecord(String string) {
    MyRecord {
        string = string + "!!!";
     // ^^^^^^ this is no longer a CtFieldWrite
    }
}

The left side of the assignment isn't a field write anymore. It is currently a CtVariableWrite.

Then I thought, okay, if the getDeclaration resolves to the field anyway, it wouldn't be a big problem, but unfortunately it resolves to the implicit parameter, which is wrong.

For example here is how IntelliJ resolves it:

When looking at this, it seems like there isn't supposed to be a parameter? Both references resolve to the field? Maybe it is just a visual thing...

I added an explicit test case for what is failing and wrote a minor surface-level patch to address this issue, but I am not very familiar with the JDT code or how the tree builder works. I think there might be a better place to resolve this issue, or is it a regression introduced by JDT?

The root cause of this seems to be PR #6316.

[Luro02]

Further investigation:

According to the JLS a compact constructor body like

MyRecord {
    string = string + "!!!";
}

does never assign to a component field (= the field of the record) of the record, and here in explicit words:

If a record declaration has a record component named c, then the simple name c in the body of a compact constructor denotes the implicit formal parameter named c, and not the component field named c.

So the current behavior seems to be correct, even though it is confusing...