Maven cannot automatically detect "provide javax.annotation.processing.Processor with ... " when using annotation processors

[benrushcc]

Affected version

latest version

Bug description

`module mod.processor {
requires java.compiler;
provides javax.annotation.processing.Processor with mod.processor.Proc;

exports mod.processor;

}`

module mod.user { exports mod.user; requires mod.processor; }

When declaring two modules, mod.processor as an annotation processor module, and mod.user as a application module, using processor in would be failing because maven cannot automatically detect it.

The current fix would be adding META-INF/services to manually expose the SPI interface.

I know it's a particular maven issue because when using javac and jar command directly would succeed without META-INF/services provided.

[cstamas]

Which Maven specifically (if "latest" is master, what commit hash? And what Java version too)? Maven 4 is getting rid of (black) "magic" in this area... Can you provide a reproducer?

@desruisseaux ping

[desruisseaux]

More details are needed. Which version of the Maven Compiler Plugin? What is the error: is it a compilation error, or an error at runtime?

If adding an META-INF/services/ fix the problem, it suggests that it is a class-path versus module-path issue. In such case, I suggest to try with Maven 4 and Maven Compiler Plugin 4, which allow developers to control explicitly whether they want a dependency on the class-path or module-path.

[benrushcc]

I think all the maven 3.x series and maven-compiler-plugin 3.x series got this issue. I haven't tried maven 4 yet since it's currently not GA. It's a problem when running moduler jar on classpath, but I think this problem is not a big deal, since META-INF/services/ has to be provided for compatiblity reasons.

[desruisseaux]

It's a problem when running moduler jar on classpath

Indeed, in such case the developer needs to provide a META-INF/services/ file. It is not generated automatically by the compiler plugin. In order to use the module-info.class file, the JAR must be placed on the module-path.