RFR: 8335989: Implement Module Import Declarations (Second Preview)

[Alan Bateman]

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

test/jdk/java/lang/module/ModuleDescriptorTest.java line 1574:

> 1572:     }
> 1573: 
> 1574:     private byte[] setClassFileVersion(int major, int minor, byte[] bytecode) {

Would it be possible to add a method description and re-format the overly long lines as it's currently impossible to look at the change side-by-side.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21431#discussion_r1794655877