RFR: 8375433: jar should validate automatic module names [v2]

[Jorn Vernee]

On Mon, 26 Jan 2026 08:36:39 GMT, Christian Stein <cstein at openjdk.org> wrote:

>> Please review this change to make `jar --validate` check an automatic module name given in a manifest file, via the `Automatic-Module-Name` attribute.
>> 
>> Prior to this commit, a `MANFEST.MF` reading
>> 
>> Automatic-Module-Name: default
>> 
>> added into a JAR file named `a.jar` would not fail when passed to `jar --validate --file a.jar`. However, it does fail when the JAR file is put on the module path of the Java launcher. For example:
>> 
>> $ java --module-path a.jar --describe-module default
>> 
>> Error occurred during initialization of boot layer
>> java.lang.module.FindException: Unable to derive module descriptor for a.jar
>> Caused by: java.lang.module.FindException: Automatic-Module-Name: default: Invalid module name: 'default' is not a Java identifier
>> 
>> 
>> With this change applied, `jar --validate --file a.jar` will print an error message and return a non-zero exit value:
>> 
>> 
>> invalid module name of Automatic-Module-Name entry in manifest: default
>> 
>> 
>> The new check also fails for when the module name of a compiled module descriptor differs from the value given in the manifest file of the same JAR file.
>
> Christian Stein has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Address review comments

Marked as reviewed by jvernee (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/29316#pullrequestreview-3712337343