AspectJ 1.9.8

Please note that Bugzilla for issue management is deprecated and new issues should be filed as GitHub issues. The list of issues addressed for 1.9.8 can be found here for Bugzilla and here for GitHub issues.

New features

AspectJ 1.9.8 supports Java 17 and its final and preview features, such as:

• Sealed classes (final in Java 17, previews in Java 15, 16 and AspectJ 1.9.7)
• Pattern matching for switch

Improvements

The --release N compiler option for correct cross-compilation to previous JDK bytecode + API versions is now supported by AJC. Previously, the option existed (inherited by ECJ) but did not work correctly.

The following new properties can improve performance, e.g. Spring start-up time:

• org.aspectj.apache.bcel.useSingleRepositoryInstance
• org.aspectj.apache.bcel.useUnavailableClassesCache
• org.aspectj.apache.bcel.ignoreCacheClearRequests

For now, they all default to false for backward compatibility. This might change in a future Aspect release, if user feedback is positive and no negative side effects are found. Please try using them as much as you can and report back questions (to the AspectJ users mailing list) or problems (as a GitHub issue), if any. Thanks to Stefan Starke for his contribution. See also PR #37.

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):

• Cross-compilation to legacy JDK : An example class which only works correctly on JDK 8 when compiled with --release 8 due to API changes in the JDK. Simply -source 8 -target 8 would not be enough in this case.
• Pattern matching for switch

Other changes and bug fixes

• 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+.
• Document build profiles and properties in docs/developer/BUILD.md
• Add a guide for setting up an AspectJ development environment in docs/developer/IDE.md
• Fix issue #105: Compilation fails when using an aspect library via -aspectpath in combination with introducing an annotation via ITD. This was broken since version 1.9.5 and fixed in 1.9.8.RC3.
• Fix issue #68: Correctly process class files containing dynamic class-file constants (JEP 309), which were introduced in Java 11 and broken in AspectJ ever since their introduction in 1.9.2. Java itself currently does not use "condy" and neither do other widespread JVM languages. Byte code engineering libraries like ASM or Byte Buddy and some instrumentation tools like JaCoCo can however produce condy code. Therefore, in order to create a regression test, we actually had to craft a condy class with ASM.
• Thanks to Andrey Turbanov for several clean code contributions and to Dmitry Mikhaylov for fixing a potential concurrency problem.

AspectJ usage hints

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.

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.

Available: 1.9.8 available 11-Feb-2022