[MNG-6490] Maven fails reporting circular dependency when the depende…

…ncy is a classified secondary artifact

maven-model-builder/src/main/java/org/apache/maven/model/validation/DefaultModelValidator.java

@@ -546,21 +546,21 @@ private void validate20RawDependenciesSelfReferencing( ModelProblemCollector pro
                                                            List<Dependency> dependencies, String prefix,
                                                            ModelBuildingRequest request )
     {
-        // We only check for groupId/artifactId cause if there is another
-        // module with the same groupId/artifactId this will fail the build
+        // We only check for groupId/artifactId/version/classifier cause if there is another
+        // module with the same groupId/artifactId/version/classifier this will fail the build
         // earlier like "Project '...' is duplicated in the reactor.
-        // So it is sufficient to check only groupId/artifactId and not the
+        // So it is sufficient to check only groupId/artifactId/version/classifier and not the
         // packaging type.
         for ( Dependency dependency : dependencies )
         {
-            String key = dependency.getGroupId() + ":" + dependency.getArtifactId() + ":" + dependency.getVersion();
+            String key = dependency.getGroupId() + ":" + dependency.getArtifactId() + ":" + dependency.getVersion()
+                    + ( dependency.getClassifier() != null ? ":" + dependency.getClassifier() : ""  );
             String mKey = m.getGroupId() + ":" + m.getArtifactId() + ":" + m.getVersion();
             if ( key.equals( mKey ) )
             {
                 // This means a module which is build has a dependency which has the same
-                // groupId, artifactId and version coordinates. This is in consequence
-                // a self reference or in other words a circular reference which can not
-                // being resolved.
+                // groupId, artifactId, version and classifier coordinates. This is in consequence
+                // a self reference or in other words a circular reference which can not being resolved.
                 addViolation( problems, Severity.FATAL, Version.V31, prefix + " " + key, key, "is referencing itself.",
                               dependency );
 
@@ -605,14 +605,14 @@ private void validateEffectiveDependencies( ModelProblemCollector problems, Mode
     private void validateEffectiveModelAgainstDependency( String prefix, ModelProblemCollector problems, Model m,
                                                           Dependency d, ModelBuildingRequest request )
     {
-        String key = d.getGroupId() + ":" + d.getArtifactId() + ":" + d.getVersion();
+        String key = d.getGroupId() + ":" + d.getArtifactId() + ":" + d.getVersion()
+                + ( d.getClassifier() != null ? ":" + d.getClassifier() : ""  );
         String mKey = m.getGroupId() + ":" + m.getArtifactId() + ":" + m.getVersion();
         if ( key.equals( mKey ) )
         {
             // This means a module which is build has a dependency which has the same
-            // groupId, artifactId and version coordinates. This is in consequence
-            // a self reference or in other words a circular reference which can not
-            // being resolved.
+            // groupId, artifactId, version and classifier coordinates. This is in consequence
+            // a self reference or in other words a circular reference which can not being resolved.
             addViolation( problems, Severity.FATAL, Version.V31, prefix + " " + key, key, "is referencing itself.", d );
 
         }

maven-model-builder/src/test/java/org/apache/maven/model/validation/DefaultModelValidatorTest.java

@@ -729,6 +729,13 @@ public void testSelfReferencingDependencyInRawModel()
 
     }
 
+    public void testSelfReferencingDependencyWithClassifierInRawModel() throws Exception
+    {
+        SimpleProblemCollector result = validateRaw( "raw-model/self-referencing-classifier.xml" );
+
+        assertViolations( result, 0, 0, 0 );
+    }
+
     public void testCiFriendlySha1()
         throws Exception
     {

maven-model-builder/src/test/resources/poms/validation/raw-model/self-referencing-classifier.xml

@@ -0,0 +1,39 @@
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>com.example.group</groupId>
+  <artifactId>testvalidpom</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+
+  <description>
+    This will test if the module validator recognized that this dependency with classifier
+    is not the same as the module itself.
+  </description>
+  <dependencies>
+    <dependency>
+      <groupId>com.example.group</groupId>
+      <artifactId>testvalidpom</artifactId>
+      <version>0.0.1-SNAPSHOT</version>
+      <classifier>linux</classifier>
+    </dependency>
+  </dependencies>
+</project>