Integrated: 8374545: Drop logic for unchecked nullness conversions

[Maurizio Cimadamore]

On Mon, 5 Jan 2026 17:48:00 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> This PR removes the recursive checks for nullness conversions.
> We might need more warnings in the future, but of a much simpler kind, so the best way forward is to restore the code in `Types` and `Check` closer to what's in mainline, and take it from there.
> 
> I've left two changes:
> * the sutyping test from `null` to `Foo!` still fails
> * a cast from `null` to `Foo!` still fails
> 
> We might want to detune these as warnings (or not).

This pull request has now been integrated.

Changeset: 8dd9ea1f
Author:    Maurizio Cimadamore <mcimadamore at openjdk.org>
URL:       https://git.openjdk.org/valhalla/commit/8dd9ea1fcff8bb5d3ce5853069754bd360fb5a7b
Stats:     250 lines in 7 files changed: 3 ins; 206 del; 41 mod

8374545: Drop logic for unchecked nullness conversions

Reviewed-by: vromero

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PR: https://git.openjdk.org/valhalla/pull/1857