RFR: 8256867: Classes with empty PermittedSubclasses attribute cannot be extended
mchung at openjdk.java.net
Tue Dec 8 00:16:12 UTC 2020
On Mon, 7 Dec 2020 19:51:38 GMT, Harold Seigel <hseigel at openjdk.org> wrote:
> Please review this fix for JDK-8256867. This change no longer throws a ClassFormatError exception when loading a class whose PermittedSubclasses attribute is empty (contains no classes). Instead, the class is treated as a sealed class which cannot be extended nor implemented. This new behavior conforms to the JVM Spec.
> This change required changing Class.permittedSubclasses() to return an empty array for classes with empty PermittedSubclasses attributes, and to return null for non-sealed classes.
> This fix was tested with Mach5 tiers 1-2 on Linux, MacOS, and Windows, and tiers 3-5 on Linux x64.
> Thanks, Harold
Other changes look okay except the spec of `Class::getPermittedSubclasses`
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