On Thu, 19 Mar 2026 14:23:21 GMT, Jaikiran Pai <[email protected]> wrote:
>> Consider these classes:
>>
>> package p;
>> public class Lib {
>> void main(String... args) {
>> System.err.println("Lib!");
>> }
>> }
>>
>> and:
>>
>> import p.Lib;
>> public class Main extends Lib {
>> public void main() {
>> System.err.println("Main!");
>> }
>> }
>>
>>
>> Note the classes are in different packages. Running this on JDK 26 yields:
>>
>> $ jdk-26/bin/java Main.java
>> Lib!
>>
>>
>> that is not correct - the method `Lib.main(String[])` is package private,
>> and is not inherited to `Main`, i.e. not a member of `Main`, and hence the
>> launcher should not use it. The launcher should only inspect methods that
>> are members (direct or inherited) of `Main`.
>>
>> This PR fixes that by only using package-private methods in they are
>> declared in the same class as is the main class. Testing is enhanced to
>> cover all related cases I/we were able to find.
>>
>> Also please review the corresponding CSR:
>> https://bugs.openjdk.org/browse/JDK-8378555
>
> src/java.base/share/classes/jdk/internal/misc/MethodFinder.java line 107:
>
>> 105: (Modifier.isPublic(mainMethodCandidate.getModifiers()) ||
>> 106:
>> Modifier.isProtected(mainMethodCandidate.getModifiers()) ||
>> 107: initialClass.getPackage() ==
>> mainMethodCandidate.getDeclaringClass().getPackage());
>
> Hello Jan, `Class.getPackage()` doesn't specify that it will return the same
> `Package` instance for multiple calls of that method on the same `Class`
> instance. Briefly looking at the implementation, it appears that only
> `BootClassLoader` might return the same `Package` instance for multiple calls.
>
> I was going to suggest that maybe we should use `Package.equals()`, but I
> can't find an implementation of that method in `Package`, so it would again
> end up being a identity check.
>
> The other option would be checking the package name `equals()`ity but I think
> that would also additionally need a ClassLoader equality check for
> `initialClass.getClassLoader()` and
> `mainMethodCandidate.getDeclaringClass().getClassLoader()`
Right, it should use Class.getClassLoader + Class::getPackageName to check if
the two classes are in the same runtime package.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/30221#discussion_r2962299513
