[foreign-jextract] RFR: 8277070: Regularize logic for cursor -> position conversion

[Jorn Vernee]

On Fri, 12 Nov 2021 18:14:27 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> TreeMaker::toPos has the correct logic to extract a Position from a cursor, which avoids any potential NPEs. Unfortunately jextract code does not use it uniformly, especially `RecordLayoutComputer` and its subclasses. This patch turns the method into a static helper and makes the `CursorPosition` constructor private, so that other clients have to go through the static factory.

LGTM!

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Marked as reviewed by jvernee (Committer).

PR: https://git.openjdk.java.net/panama-foreign/pull/613