RFR: 8268611: jar --validate should check targeted classes in MR-JAR files

[Christian Stein]

On Thu, 12 Dec 2024 14:47:24 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Please review this change ensuring all targeted classes in a MR-JAR file should target the same or a lower classfile version.
>> 
>> For example, having compiled source files with `javac` 25 without using the `--release` option (or with `--release 25`) and trying to archive them via a `jar --create --file a.jar --release 9 ... --release 10 ...` command now fails with:
>> 
>> classfile release value of META-INF/versions/9/version/Version.class too high: 25
>> classfile release value of META-INF/versions/10/version/Version.class too high: 25
>> invalid multi-release jar file a.jar deleted
>> 
>> 
>> This pull request contains fixes to existing tests which produced invalid MR-JAR files. Most of those fixes are achieved by adding an appropriate `--release N` option to the associated `javac` call. One of those fixes rewrites the classfile version bytes between the `javac` and `jar` calls.
>
> src/jdk.jartool/share/classes/sun/tools/jar/resources/jar.properties line 94:
> 
>> 92:         unexpected versioned entry {0} for release {1}
>> 93: error.release.value.toohigh.versioned.entry=\
>> 94:         classfile release value of {0} too high: {1}
> 
> Not sure about the term 'release value' here. Is that defined somewhere?
> 
> Maybe leaning on 'class file major version' like this would work better?
> 
> Suggestion:
> 
> error.release.value.toohigh.versioned.entry=\
>         class file {0} targeting version '{1}' must have a major version lower or equal to '{2}' , but was '{3}'
> 
> 
> And then `{0}` is the entry, `{1}` is the `mrversion`, `{2}` is the class file major version associated with that `mrversion`, and `{3}` was the actual class file major version.
> 
> (also, 'class file' is two words)

In this context the actual class file major version doesn't add any value to communicate the issue to the user:
- `javac --release N` and
- `jar --release N` use the "Java release feature number" in their options, so does the
- `META-INF/versions/N` path.

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PR Review Comment: https://git.openjdk.org/jdk/pull/22103#discussion_r1882367322