[MRESOLVER-314] Getting "IllegalArgumentException: Comparison method violates its general contract!"

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.9.4
• Fix Version/s: 1.9.5
• Component/s: Resolver
• Assignee: Tamas Cservenak
• Reporter: Christian Ziech
• Created: 16/Jan/23 10:16
• Updated: 22/Feb/23 20:25
• Resolved: 17/Feb/23 08:20

Description

We are using the versions plugin to modify the version of a property in our pom files. This now fails for us because the compareTo method of the compareTo() method of the org.eclipse.aether.util.version.GenericVersion violates the assumption that the relation is transitive.

I wrote a small test which shows that 0f224b94-SNAPSHOT.compareTo(ecb174eb-SNAPSHOT) := 0 and 0f224b94-SNAPSHOT.compareTo(de09eebc-SNAPSHOT) := 0 but ecb174eb-SNAPSHOT.compareTo(de09eebc-SNAPSHOT) := 1.
This is in violation with:

Finally, the implementor must ensure that x.compareTo==0 implies that sgn(x.compareTo(z)) == sgn(y.compareTo(z)), for all z.

Here is some short demo code (truncated to the bare minimum I could find):

import org.eclipse.aether.util.version.GenericVersionScheme;
import org.eclipse.aether.version.InvalidVersionSpecificationException;
import org.eclipse.aether.version.Version;

public class TestMavenResolver {
    public void testCompare() throws InvalidVersionSpecificationException {
        String [] strs = new String [] {"0f224b94-SNAPSHOT", "ecb174eb-SNAPSHOT", "de09eebc-SNAPSHOT"};
        List<Version> versions = new ArrayList<>();
        GenericVersionScheme scheme = new GenericVersionScheme();
        for (String str: strs) {
            versions.add(scheme.parseVersion(str));
        }

        for (Version ver1 : versions) {
            for (Version ver2 : versions) {
                if (ver1 != ver2) {
                    int res = ver1.compareTo(ver2);
                    System.out.println(ver1+".compareTo("+ver2+") := "+res);
                }
            }
        }
    }
}

The output of above code is:

0f224b94-SNAPSHOT.compareTo(ecb174eb-SNAPSHOT) := 0
0f224b94-SNAPSHOT.compareTo(de09eebc-SNAPSHOT) := 0
ecb174eb-SNAPSHOT.compareTo(0f224b94-SNAPSHOT) := 0
ecb174eb-SNAPSHOT.compareTo(de09eebc-SNAPSHOT) := 1
de09eebc-SNAPSHOT.compareTo(0f224b94-SNAPSHOT) := 0
de09eebc-SNAPSHOT.compareTo(ecb174eb-SNAPSHOT) := -1

Just for reference, here is the exception we are getting:

Caused by: java.lang.IllegalArgumentException: Comparison method violates its general contract!
    at java.util.ComparableTimSort.mergeHi (ComparableTimSort.java:870)
    at java.util.ComparableTimSort.mergeAt (ComparableTimSort.java:487)
    at java.util.ComparableTimSort.mergeCollapse (ComparableTimSort.java:413)
    at java.util.ComparableTimSort.sort (ComparableTimSort.java:213)
    at java.util.Arrays.sort (Arrays.java:1315)
    at java.util.Arrays.sort (Arrays.java:1509)
    at java.util.ArrayList.sort (ArrayList.java:1750)
    at java.util.Collections.sort (Collections.java:145)
    at org.apache.maven.repository.internal.DefaultVersionRangeResolver.resolveVersionRange (DefaultVersionRangeResolver.java:168)
    at org.eclipse.aether.internal.impl.DefaultRepositorySystem.resolveVersionRange (DefaultRepositorySystem.java:247)
    at org.codehaus.mojo.versions.api.DefaultVersionsHelper.lookupArtifactVersions (DefaultVersionsHelper.java:183)
    at org.codehaus.mojo.versions.api.DefaultVersionsHelper.lookupArtifactVersions (DefaultVersionsHelper.java:236)
    at org.codehaus.mojo.versions.api.PropertyVersions.resolveAssociatedVersions (PropertyVersions.java:89)
    at org.codehaus.mojo.versions.api.PropertyVersions.<init> (PropertyVersions.java:80)
    at org.codehaus.mojo.versions.api.PropertyVersionsBuilder.newPropertyVersions (PropertyVersionsBuilder.java:86)
    at org.codehaus.mojo.versions.api.DefaultVersionsHelper.getVersionPropertiesMap (DefaultVersionsHelper.java:586)
    at org.codehaus.mojo.versions.SetPropertyMojo.update (SetPropertyMojo.java:141)
    at org.codehaus.mojo.versions.SetPropertyMojo.update (SetPropertyMojo.java:135)
    at org.codehaus.mojo.versions.AbstractVersionsUpdaterMojo.process (AbstractVersionsUpdaterMojo.java:329)
    at org.codehaus.mojo.versions.AbstractVersionsUpdaterMojo.execute (AbstractVersionsUpdaterMojo.java:270)

Issue Links

• links to: GitHub Pull Request #249