On Tue, 8 Dec 2020 14:57:26 GMT, Harold Seigel <hsei...@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 > > Harold Seigel has updated the pull request incrementally with one additional > commit since the last revision: > > 8256867: Classes with empty PermittedSubclasses attribute cannot be extended src/java.base/share/classes/java/lang/Class.java line 4399: > 4397: * that is {@link #isSealed()} returns {@code false}, then this > method returns {@code null}. > 4398: * Conversely, if {@link #isSealed()} returns {@code true}, then > this method > 4399: * returns a non-null value. @ChrisHegarty minor but I prefer a simpler alternative to address your concern is to add a link to the reference to "sealed class or interface" to `Class::isSealed` as follows: implement this class or interface if it is {@linkplain #isSealed() sealed}. The order of such elements is unspecified. If this {@code Class} object represents a primitive type, is unspecified. The array is empty if this {@linkplain #isSealed() sealed} class or interface has no permitted subclass. If this {@code Class} object represents a primitive type, {@code void}, an array type, or a class or interface that is not sealed, then this method returns {@code null}. ------------- PR: https://git.openjdk.java.net/jdk/pull/1675