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AspectJ 1.9.20

AspectJ 1.9.20.1

© Copyright 2023 Contributors. All rights reserved.

Release info: 1.9.20.1 available 04-Sep-2023

This is a bugfix release for 1.9.20, fixing two problems:

  • Regression bug 257 introduced in 1.9.20 would match negated type patterns like !void or !String[] incorrectly.

  • Spring issue 27761 describes a problem where AspectJ, when used by Spring AOP, in rare cases falsely considered bridge methods for overridden generic methods for matching, leading to falsely negative matching results. See also AspectJ tracker issue 256).

The list of issues addressed for 1.9.20.1 can be found here.

AspectJ 1.9.20

© Copyright 2023 Contributors. All rights reserved.

Release info: 1.9.20 available 16-Aug-2023

Please note that Bugzilla for issue management is deprecated and new issues should be filed as GitHub issues. The list of issues addressed for 1.9.20 can be found here:

New features

AspectJ 1.9.20 supports Java 20 and its final, preview and incubator features, such as:

  • Record patterns (preview)

  • Virtual threads (preview)

  • Pattern matching for switch (preview 3)

  • Structured concurrency (incubator)

Please note, that the upstream Eclipse Java Compiler (ECJ), which the AspectJ Compiler (AJC) is a fork of, still has some open issues concerning Java 20 preview feature support, see the list in this comment. AJC therefore inherits the same problems for the specific cases described in the linked issues.

Improvements

  • Since Java 9 and the introduction of the Java Module System, the upstream Eclipse Java Compiler (ECJ) and Eclipse Java Development Tools (JDT) had gone through some internal changes, enabling both the compiler and the IDE to handle new Java language features. In AspectJ, some of those internal changes have not been properly upgraded for quite a while, but this is now fixed. However, it might require you to recompile your aspects and projects/classes using them. Otherwise, you might get problems in Eclipse IDE or under certain circumstances even when running newly compiled aspects in older AspectJ versions and vice versa. You are on the safe side if you simply rebuild your projects. We are sorry for the inconvenience, but we have to follow upstream ECJ and JDT changes.

  • Along with fixing GitHub bug 24, the syntax for array type matching has been improved considerably. You can find some examples here.

Code examples

You can find some sample code in the AspectJ test suite under the respective AspectJ version in which the features were first supported (possibly as JVM preview features):

Other changes and bug fixes

  • About a dozen bugs have been fixed, some of them quite old. See "list of issues addressed" further above and follow the link to GitHub to find out if your issue is among them.

AspectJ usage hints

AspectJ compiler build system requirements

Since 1.9.8, the AspectJ compiler ajc (contained in the aspectjtools library) no longer works on JDKs 8 to 10. The minimum compile-time requirement is now JDK 11 due to upstream changes in the Eclipse Java Compiler (subset of JDT Core), which AspectJ is a fork of. You can still compile to legacy target versions as low as Java 1.3 when compiling plain Java code or using plain Java ITD constructs which do not require the AspectJ runtime aspectjrt, but the compiler itself needs JDK 11+. Just like in previous AspectJ versions, both the runtime aspectjrt and the load-time weaver aspectjweaver still only require JRE 8+.

Use LTW on Java 16+

Please note that if you want to use load-time weaving on Java 16+, the weaving agent collides with JEP 396 (Strongly Encapsulate JDK Internals by Default). Therefore, you need to set the JVM parameter --add-opens java.base/java.lang=ALL-UNNAMED in order to enable aspect weaving. This is due to the fact that the weaver uses internal APIs for which we have not found an adequate replacement yet when defining classes in different classloaders.

Update: As of AspectJ 1.9.21.1, --add-opens is no longer necessary. Please upgrade, if it bothers you too much.

Compile with Java preview features

For features marked as preview on a given JDK, you need to compile with ajc --enable-preview and run with java --enable-preview on that JDK.

Please note, that you cannot run code compiled with preview features on any other JDK than the one used for compilation. For example, records compiled with preview on JDK 15 cannot be used on JDK 16 without recompilation. This is a JVM limitation unrelated to AspectJ. Also, e.g. sealed classes are preview-1 on JDK 15 and preview-2 on JDK 16. You still need to recompile, no matter what.