Hello Ralf
Le 05/12/2025 à 07:13, Ralf Ueberfuhr via dev a écrit :
Why are processor-typed dependencies included, when annotation
processing is only happening at build time?
Maven 4 unifies two aspects which, previously, were handled in
heterogeneous ways:
* Declaration of source and resources (with the new <sources> element).
* Declaration of the locations where to place dependencies.
The second item come from a need to control whether to place a
dependency on the class-path or module-path. This choice can change the
behavior of a library. Maven 3 tries to guess (it is still the default
in Maven 4), which is sometime correct but is problematic when the guess
is not correct. For giving control to the developers, new types were
added: classpath-jar and modular-jar.
Since the above uses dependency type as a way to control where to place
the dependency, the idea could be generalized to other kinds of path:
processor path, doclet path, taglet path, maybe more in the future.
Therefore, processor type is an extension of above idea meaning that the
target of the dependency is neither the class-path or module-path, but
the processor-path. In the future, we may continue with the same idea,
with the addition of "taglet" and "doclet" types meaning to put the
dependency on the taglet path or doclet path. They would be in a
situation similar to the processor type, used only at build time.
An advantage of this approach is that the dependencies are managed like
ordinary dependencies, rather than a plugin-specific configuration that
duplicates code from Maven core. I'm not sure that dependency managed by
plugin code had all the functionalities of dependencies managed by Maven
core (but others Maven developer would know better than me).
Note: there is an issue with the current code, which is that the
transitive dependencies of an annotation processor are not handled
correctly yet. I think that Tamas has a pull request in Maven core for
that issue.
Martin
