[tycho-version-plugin] Since 4.0.5 non-matching version of child modules are forcefully overwritten

[sratz]

tycho-version-plugin:set-version states:

Sets the version of the current project and child projects with the same version, and updates references as necessary.

Consider the following structue:

pom.xml: version=2.0.0 [modules=P,Q]
P/pom.xml: version=2.0.0, parent=2.0.0 [modules=m1,m2]
P/m1/pom.xml: version=2.0.0, parent=2.0.0
P/m2/pom.xml: version=2.0.0, parent=2.0.0
Q/pom.xml: version=1.0.0, parent=2.0.0 [modules=m3,m4]
Q/m3/pom.xml: version=1.0.0, parent=1.0.0
Q/m4/pom.xml: version=1.0.0, parent=1.0.0

Execute: set-version -DnewVersion=2.0.1

Result with Tycho <= 4.0.4:

pom.xml: version=2.0.1 [modules=P,Q]
P/pom.xml: version=2.0.1, parent=2.0.1 [modules=m1,m2]
P/m1/pom.xml: version=2.0.1, parent=2.0.1
P/m2/pom.xml: version=2.0.1, parent=2.0.1
Q/pom.xml: version=1.0.0, parent=2.0.1 [modules=m3,m4]
Q/m3/pom.xml: version=1.0.0, parent=1.0.0
Q/m4/pom.xml: version=1.0.0, parent=1.0.0

Result with Tycho >= 4.0.5:

pom.xml: version=2.0.1 [modules=P,Q]
P/pom.xml: version=2.0.1, parent=2.0.1 [modules=m1,m2]
P/m1/pom.xml: version=2.0.1, parent=2.0.1
P/m2/pom.xml: version=2.0.1, parent=2.0.1
Q/pom.xml: version=2.0.1, parent=2.0.1 [modules=m3,m4]
Q/m3/pom.xml: version=2.0.1, parent=2.0.1
Q/m4/pom.xml: version=2.0.1, parent=2.0.1

This is incorrect as the with the same version contract is violated and also all the mis-matching versions of 1.0.0 are forcefully updated to 2.0.1.

This is a side-effect of #3341 / #3343

[laeubi]

@sratz do you like to add this as a testcases here and propose a fix:

https://github.com/eclipse-tycho/tycho/tree/main/tycho-its/projects/tycho-version-plugin/set-version

[sratz]

@sratz do you like to add this as a testcases here and propose a fix:

https://github.com/eclipse-tycho/tycho/tree/main/tycho-its/projects/tycho-version-plugin/set-version

Yes, however I am trying to put my head around the intention of #3341 / #3343: Am I understanding it right that

• before: Nested projects were only updated when a child module also had a <parent> reference back?
• after: Nested projects are also updated even when they do not have a <parent> reference?

Why was this needed? My gut feeling tells me that if a child module does not link to a <parent>, it should be considered more loosely coupled and not updating its version is probably OK?

[laeubi]

Well the problem is that the set-version mojo is somehow "limited" and only a few cases are covered and often in "real" setups you get surprising results. e.g there are cases where are multiple parents and maybe aggregator poms that only list childs, in your example A = pom.xml: version=2.0.1 [modules=P,Q] aggregates P+Q, now assume that P does not has a parent ref to A then the mojo will only update A but nothing else even though all projects are part of the reactor.

So basically, everything that is in the reactor should be considered as maven is considering that as well, there is no need for a direct parent/child relation.