versionPolicyReportDependencyIssues requires versionPolicyIntention to be set

[rtyley]

I think the versionPolicyReportDependencyIssues command is the only way to debug the reasons sbt-version-policy has for deciding that compatibility is broken by dependency changes, ie the reasons that require a major/minor version bump of releaseVersion when running in unconstrained compatibility mode without versionPolicyIntention set.

Unfortunately, versionPolicyReportDependencyIssues requires versionPolicyIntention is set, and will give this error if it's not set:

Please set the key versionPolicyIntention to declare the compatibility you want to check

sbt-version-policy/sbt-version-policy/src/main/scala/sbtversionpolicy/SbtVersionPolicySettings.scala

Lines 179 to 181 in 106d598

	val intention =
	versionPolicyIntention.?.value
	.getOrElse(throw new MessageOnlyException("Please set the key versionPolicyIntention to declare the compatibility you want to check"))

This is awkward for projects running in unconstrained compatibility mode - ie all projects using gha-scala-library-release-workflow! There is useful output of versionPolicyReportDependencyIssues that we'd like to see even if versionPolicyIntention is not set, like:

[error] Incompatibilities with dependencies of simple-configuration-s3:3.0.0
[error]   io.netty:netty-buffer: incompatible version change from 4.1.114.Final to 4.1.115.Final (compatibility: early semantic versioning)
[error]   io.netty:netty-codec: incompatible version change from 4.1.114.Final to 4.1.115.Final (compatibility: early semantic versioning)

Workaround

Temporarily set versionPolicyIntention on the sbt console, like this:

set ThisBuild / versionPolicyIntention := Compatibility.BinaryAndSourceCompatible ; versionPolicyReportDependencyIssues

Alternatives

You can use the versionPolicyCollectCompatibilityReports task, which doesn't require versionPolicyIntention, but the output isn't as user-friendly as versionPolicyReportDependencyIssues:

show versionPolicyCollectCompatibilityReports
[info] core / versionPolicyCollectCompatibilityReports
[info] 	CompatibilityReport(Some(CompatibilityModuleReport(com.gu:simple-configuration-core:3.0.0,None,DependencyCheckReport(Map(BinaryIncompatibility -> Map((com.typesafe,config) -> SameVersion(1.4.3), (io.netty,netty-resolver) -> IncompatibleVersion(4.1.115.Final,4.1.114.Final,EarlySemVer), (io.netty,netty-transport) -> IncompatibleVersion(4.1.115.Final,4.1.114.Final,EarlySemVer)
...

[julienrf]

Thank you for the detailed write up! How do you think the problem should be solved? My intuition is that we want versionPolicyAssessCompatibility to return more than just a Compatibility value for each module. It could report the found incompatibilities (see also #121 which implements something similar)