SONARJAVA-1299 ignores parameters annotated with @observes

Author: Wohops

java-checks/pom.xml

@@ -162,6 +162,11 @@
                   <version>1.3</version>
                   <type>jar</type>
                 </artifactItem>
+                <artifactItem>
+                  <groupId>javax</groupId>
+                  <artifactId>javaee-api</artifactId>
+                  <version>7.0</version>
+                </artifactItem>
               </artifactItems>
               <outputDirectory>${project.build.directory}/test-jars</outputDirectory>
             </configuration>

java-checks/src/main/java/org/sonar/java/checks/unused/UnusedMethodParameterCheck.java

@@ -30,6 +30,7 @@
 import org.sonar.java.model.declaration.MethodTreeImpl;
 import org.sonar.java.tag.Tag;
 import org.sonar.plugins.java.api.JavaFileScannerContext;
+import org.sonar.plugins.java.api.semantic.Symbol;
 import org.sonar.plugins.java.api.tree.BlockTree;
 import org.sonar.plugins.java.api.tree.IdentifierTree;
 import org.sonar.plugins.java.api.tree.MethodTree;
@@ -53,6 +54,8 @@
 @SqaleConstantRemediation("5min")
 public class UnusedMethodParameterCheck extends SubscriptionBaseVisitor {
 
+  private static final String AUTHORIZED_ANNOTATION = "javax.enterprise.event.Observes";
+
   @Override
   public List<Tree.Kind> nodesToVisit() {
     return ImmutableList.of(Tree.Kind.METHOD, Tree.Kind.CONSTRUCTOR);
@@ -64,7 +67,8 @@ public void visitNode(Tree tree) {
     if (hasSemantic() && methodTree.block() != null && !isExcluded(methodTree)) {
       List<IdentifierTree> unused = Lists.newArrayList();
       for (VariableTree var : methodTree.parameters()) {
-        if (var.symbol().usages().isEmpty()) {
+        Symbol symbol = var.symbol();
+        if (symbol.usages().isEmpty() && !symbol.metadata().isAnnotatedWith(AUTHORIZED_ANNOTATION)) {
           unused.add(var.simpleName());
         }
       }

java-checks/src/main/resources/org/sonar/l10n/java/rules/squid/S1172.html

@@ -15,7 +15,7 @@ <h2>Compliant Solution</h2>
 </pre>
 <h2>Exceptions</h2>
 
-<p>Override and implementation methods are excluded, as are methods that are intended to be overridden.</p>
+<p>Override and implementation methods are excluded, as are parameters annotated with <code>@Observes</code>, and methods that are intended to be overridden.</p>
 <pre>
 @override
 void doSomething(int a, int b) {     // no issue reported on b
@@ -37,7 +37,7 @@ <h2>Exceptions</h2>
 <h2>See</h2>
 
 <ul>
-<li> MISRA C++:2008, 0-1-11</li>
-<li> MISRA C:2012, 2.7</li>
+<li> MISRA C++:2008, 0-1-11 - There shall be no unused parameters (named or unnamed) in nonvirtual functions.</li>
+<li> MISRA C:2012, 2.7 - There should be no unused parameters in functions</li>
 </ul>
 

java-checks/src/test/files/checks/unused/UnusedMethodParameterCheck.java

@@ -1,3 +1,6 @@
+import javax.annotation.Nonnull;
+import javax.enterprise.event.Observes;
+
 class A extends B{
   void doSomething(int a, int b) { // Noncompliant {{Remove this unused method parameter "b".}} [[sc=31;ec=32]]
     compute(a);
@@ -34,7 +37,7 @@ void foo(int a) {
 }
 
 class D extends C {
-  void foo(int b, int a) { // Noncompliant {{Remove this unused method parameter "b".}} [[sc=16;ec=17;secondary=37]]
+  void foo(int b, int a) { // Noncompliant {{Remove this unused method parameter "b".}} [[sc=16;ec=17;secondary=40]]
     System.out.println("");
   }
 }
@@ -97,5 +100,14 @@ private qiz(int arg1, int arg2) {
   public Supplier<String> parameterNotUsed(final Object o) {
     return o::toString;
   }
+}
 
+class Annotations {
+  public void foo(@Observes Object event, int arg2) { // Compliant
+    System.out.println(arg2);
+  }
+
+  public void bar(@Nonnull Object event, int arg2) { // Noncompliant {{Remove this unused method parameter "event".}} [[sc=35;ec=40]]
+    System.out.println(arg2);
+  }
 }