Integrated: 8335989: Implement JEP 494: Module Import Declarations (Second Preview)

[Jan Lahoda]

On Wed, 9 Oct 2024 19:22:01 GMT, Jan Lahoda <jlahoda at openjdk.org> wrote:

> This is a current patch for module imports declarations, second preview. At least the JEP number and preview revision will need to be updated in `jdk.internal.javac.PreviewFeature.Feature`, but otherwise I believe this is ready to receive feedback.
> 
> The main changes are:
> - `requires transitive java.base;` is permitted, under the preview flag. Both javac and the runtime module system are updated to accept this directive when preview is enabled.
> - the `java.se` module is using `requires transitive java.base;`, and is deemed to be participating in preview, so its classfile version is not tainted. Runtime is updated to access `requires transitive java.base;` in any `java.*`, considering all of them to be participating in preview. Can be tighten up to only `java.se` is desired.
> - the types imported through module imports can be shadowed using on-demand imports. So, for example, having:
> 
> import module java.base;
> import module java.desktop;
> ...
> List l;//ambigous
> 
> but:
> 
> import module java.base;
> import module java.desktop;
> import java.util.*;
> ...
> List l;//not ambigous, reference to java.util.List

This pull request has now been integrated.

Changeset: 1e97c1c9
Author:    Jan Lahoda <jlahoda at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/1e97c1c913220b07ff0c1c977cea80bc9436729d
Stats:     762 lines in 28 files changed: 580 ins; 46 del; 136 mod

8335989: Implement JEP 494: Module Import Declarations (Second Preview)

Reviewed-by: vromero, abimpoudis, mcimadamore, alanb

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PR: https://git.openjdk.org/jdk/pull/21431