Subject: [PATCH] Add maven-build-system.
From: Julien Lepiller <[email-masked]>
To: [email-masked]
Date: Sun, 28 Jun 2020 03:41:35 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

Hi Guix!

This patch series adds the maven-build-system, at last! You can find
the patches on the wip-maven-build-system branch of my repository, at
https://framagit.org/tyreunom/guix/-/tree/wip-maven-build-system

I haven't sent the patches on this mailing because there are ~100 of
them. If you prefer, I'll send the series with git send-patch.

Here is a summary of the changes:

guix: java-utils: Add Maven-related phases.

This patch adds some functionalities to guix/build/java-utils.scm, in
particular the install-from-pom and install-pom-file functions that are
phases you can use instead of the install phase. As their name
suggests, they install a package from a pom.xml file to a maven
repository directory structure in lib/m2. install-pom-file only
installs a single pom.xml file, instead of the file and its jar.

gnu: java-asm: Remove dependency on bnd libraries.
...
gnu: java-jarjar: unbundle maven-plugin-api.

This small series of patches improves the bootstrap of java-junit by
not relying on bundled libraries (binaries), by enabling tests in junit
and by reducing the number of dependencies that must be built before
junit. Junit is now fully bootstrapped.

gnu: java-junit: Install from pom file.

This patch converts junit and its dependencies to the maven repository
structure. It also takes care of changing junit's dependents that had a
hardcoded path to the junit jar file.

gnu: Add apache-parent-pom-13.
...
gnu: Add maven-components-parent-pom-21.

This series adds many parent pom packages to a new file,
maven-parent-pom.scm.  A parent pom is a single pom.xml file that
contains information about a project. Actual packages can then
reference these files to inherit some or all of these information.

gnu: java-commons-lang3: Update to 3.9.
...
gnu: maven: Install from pom file.

These patches update some dependencies of maven and the maven build
system, and convert them so they are installed in the maven repository
structure.

gnu: maven-shared-utils: Fix /bin/sh invocation.
gnu: java-modello-core: Propagate inputs.

These two patches implement fixes that are required later on.

gnu: Add java-plexus-digest.
...
gnu: Add maven-jar-plugin.

This patch series adds more packages that are maven plugins or their
dependencies.  Maven doesn't do anything by itself, it's simply a
dependency/lifecycle manager.  It requires plugins to actually do
things such as compiling, creating a jar archive, installing, testing,
etc... This is what these patches implement.

guix: Add maven-build-system.

The actual commit that adds the maven-build-system :)

In the end, the maven-build-system only has the very basic plugins by
default, but it is able to compile, test and install a simple hello
world example application, generated by maven (see test.scm attached).

Next step is building the maven-plugin-plugin, which is the plugin that
builds other plugins. Currently the plugins are built with a custom
plugin.xml generator that uses a buggy java parser, so I don't want to
rely on it for other plugins. Note that we can't use the
maven-plugin-plugin to build any of the current plugins, since they are
needed to build themselves...

I also noticed that our maven is acting weird wrt lifecycles: it seems
to be doing some test-related work during the build step, and rebuilds
in the test and install steps. This is weird, but I'm not sure how to
fix. Re-building maven with the maven-build-system might give as a
better version of maven. I don't really want to investigate that now,
that's why I'm sending the patch series anyway.

Hope you enjoy!