[java] New rule: StaticNestedRecord

Add the rule to check that nested record are not declared with static modifier

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/codestyle/UnnecessaryModifierRule.java

@@ -24,6 +24,7 @@ import net.sourceforge.pmd.lang.java.ast.ASTEnumDeclaration;
 import net.sourceforge.pmd.lang.java.ast.ASTFieldDeclaration;
 import net.sourceforge.pmd.lang.java.ast.ASTMethodDeclaration;
 import net.sourceforge.pmd.lang.java.ast.ASTMethodOrConstructorDeclaration;
+import net.sourceforge.pmd.lang.java.ast.ASTRecordDeclaration;
 import net.sourceforge.pmd.lang.java.ast.ASTResource;
 import net.sourceforge.pmd.lang.java.ast.AccessNode;
 import net.sourceforge.pmd.lang.java.ast.internal.PrettyPrintingUtil;
@@ -42,6 +43,7 @@ public class UnnecessaryModifierRule extends AbstractJavaRule {
         addRuleChainVisit(ASTFieldDeclaration.class);
         addRuleChainVisit(ASTAnnotationMethodDeclaration.class);
         addRuleChainVisit(ASTConstructorDeclaration.class);
+        addRuleChainVisit(ASTRecordDeclaration.class);
     }
 
 
@@ -264,6 +266,14 @@ public class UnnecessaryModifierRule extends AbstractJavaRule {
         return data;
     }
 
+    @Override
+    public Object visit(ASTRecordDeclaration node, Object data) {
+        if (node.isStatic()) {
+            reportUnnecessaryModifiers(data, node, Modifier.STATIC, "record are implicitly static");
+        }
+        return data;
+    }
+
 
     private boolean isSafeVarargs(final ASTMethodDeclaration node) {
         return node.isAnnotationPresent(SafeVarargs.class.getName());

pmd-java/src/main/resources/category/java/codestyle.xml

@@ -2062,6 +2062,12 @@ public class Bar {
         FOO;
     }
 }
+public class FooClass {
+    static record BarRecord() {}     // static ignored
+}
+public interface FooInterface {
+    static record BarRecord() {}     // static ignored
+}
 ]]>
         </example>
     </rule>

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/codestyle/xml/UnnecessaryModifier.xml

@@ -695,6 +695,52 @@ public interface Bar {
     void method() {
     }
     static class Foo {}
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Static is not necessary in class</description>
+        <expected-problems>1</expected-problems>
+        <expected-messages>
+            <message>Unnecessary modifier 'static' on record 'BarRecord': record are implicitly static</message>
+        </expected-messages>
+        <code><![CDATA[
+public class FooClass {
+    static record BarRecord() {}
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Correct nested record declaration in classes</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public class FooClass {
+    record BarRecord() {}
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Static is not necessary in interface</description>
+        <expected-problems>1</expected-problems>
+        <expected-messages>
+            <message>Unnecessary modifier 'static' on record 'BarRecord': record are implicitly static</message>
+        </expected-messages>
+        <code><![CDATA[
+public interface FooInterface {
+    static record BarRecord() {}
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Correct nested record declaration in interface</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public interface FooInterface {
+    record BarRecord() {}
 }
         ]]></code>
     </test-code>