[MNG-8191] [reactor build order] modules used in dependencyManagement-section with scope import should be ordered first

[jira-importer]

Reto Hoehener opened MNG-8191 and commented

I asked about this on Stack Overflow: https://stackoverflow.com/questions/77060268/why-is-an-imported-pom-module-not-ordered-at-the-beginning-of-the-maven-multi-mo

I value the responses by Karl Heinz Marbaise but would kindly ask the Maven community to consider this again.

I understand that the management sections do not actually declare dependencies (or plugins). But - same as a parent pom - they do manage versions, which can affect the actual versions used for real dependencies and plugins.

I will of course provide more examples or details if necessary.

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Affects: 3.0

Issue Links:

• MNG-8009 BOM peculiarities with build ordering

[jira-importer]

Tamas Cservenak commented

Within reactor no BOM should be used, but plain inheritance. See MNG-8012.

[jira-importer]

Reto Hoehener commented

Tamas Cservenak Interesting, thanks for the links. At least I'm not imagining things.

Why are you opting to forbid imported poms in reactor builds?

As long as the dependency tree is an acyclic directed tree, I don't immediately see why you can't order them first in the reactor and allow it.

I am actually working on removing "BOM POMs" so hopefully this won't affect me when Maven 4 becomes mainstream, but just for context: currently we have a flat module structure and some projects import some BOM poms in their dependency management sections.

[jira-importer]

Tamas Cservenak commented

BOMs are meant for "inter project" version management mainly. In reactor (so within one multi module build) use rather plain inheritance. So, one is for "export/import" (across project borders) while the other is meant for "domestic use".

[jira-importer]

Reto Hoehener commented

We generate a reactor pom that contains every project in our flat SCM structure. This reactor pom is very convenient for CI builds, or license/coverage/codestyle analysis. But it means there is no straightforward inheritance relationship (or any relationship at all) between some of these modules.

So yes, our BOMs are inter-project, but our reactor as well...

[jira-importer]

Reto Hoehener commented

Another big advantage of the reactor for us is that it can run in parallel but still ordered, dramatically reducing the build time. As opposed to for example a plain generated script that calls some maven command for every project.

[gnodet]

Fixed by #13040 (merged on master) / #13262 (maven-4.0.x) / #13263 (maven-3.10.x): ProjectSorter now treats dependencyManagement BOM imports (scope=import, type=pom) as reactor graph edges, so modules used as BOMs are correctly ordered before their consumers. The -am exclusion bug reported in #11397 is also resolved by the same change.