[MNG-4312] Magic expressions injected by PluginParameterExpressionEvalutor conflict with expressions used by plugins to access system properties

git-svn-id: https://svn.apache.org/repos/asf/maven/components/trunk@806286 13f79535-47bb-0310-9956-ffa450edef68

maven-core/src/main/java/org/apache/maven/plugin/PluginParameterExpressionEvaluator.java

@@ -28,7 +28,7 @@ import org.apache.maven.plugin.descriptor.PluginDescriptor;
 import org.apache.maven.project.MavenProject;
 import org.apache.maven.project.path.PathTranslator;
 import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluationException;
-import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluator;
+import org.codehaus.plexus.component.configurator.expression.TypeAwareExpressionEvaluator;
 import org.codehaus.plexus.logging.Logger;
 import org.codehaus.plexus.util.introspection.ReflectionValueExtractor;
 
@@ -36,7 +36,7 @@ import org.codehaus.plexus.util.introspection.ReflectionValueExtractor;
  * @author Jason van Zyl
  */
 public class PluginParameterExpressionEvaluator
-    implements ExpressionEvaluator
+    implements TypeAwareExpressionEvaluator
 {
     private MavenSession session;
 
@@ -94,6 +94,12 @@ public class PluginParameterExpressionEvaluator
 
     public Object evaluate( String expr )
         throws ExpressionEvaluationException
+    {
+        return evaluate( expr, null );
+    }
+
+    public Object evaluate( String expr, Class<?> type )
+        throws ExpressionEvaluationException
     {
         Object value = null;
 
@@ -295,6 +301,19 @@ public class PluginParameterExpressionEvaluator
             }
         }
 
+        /*
+         * MNG-4312: We neither have reserved all of the above magic expressions nor is their set fixed/well-known (it
+         * gets occasionally extended by newer Maven versions). This imposes the risk for existing plugins to
+         * unintentionally use such a magic expression for an ordinary system property. So here we check whether we
+         * ended up with a magic value that is not compatible with the type of the configured mojo parameter (a string
+         * could still be converted by the configurator so we leave those alone). If so, back off to evaluating the
+         * expression from properties only.
+         */
+        if ( value != null && type != null && !( value instanceof String ) && !type.isInstance( value ) )
+        {
+            value = null;
+        }
+
         if ( value == null )
         {
             // The CLI should win for defining properties

pom.xml

@@ -42,7 +42,7 @@
     <commonsCliVersion>1.2</commonsCliVersion>
     <easyMockVersion>1.2_Java1.3</easyMockVersion>
     <junitVersion>3.8.2</junitVersion>
-    <plexusVersion>1.1.0</plexusVersion>
+    <plexusVersion>1.2.0</plexusVersion>
     <plexusInterpolationVersion>1.11</plexusInterpolationVersion>
     <plexusPluginManagerVersion>1.0-alpha-1</plexusPluginManagerVersion>
     <plexusUtilsVersion>1.5.15</plexusUtilsVersion>