Fix for detector UncallableMethodOfAnonymousClass to not report unu…

…sed methods of method-local enumerations and records

During compilation, enumerations and records are turned into Java classes with some auto-generated methods. Some of these methods are called by the code but some of them not. However, this is not a programming error or bad practice, these methods must not be considered as dead code because their generation cannot be prevented. Therefore no bug report `UMAC_UNCALLABLE_METHOD_OF_ANONYMOUS_CLASS` must be issued to such classes even if they are defined inside a method. See issue ([spotbugs#2120](spotbugs#2120))

CHANGELOG.md

@@ -7,6 +7,7 @@ Currently the versioning policy of this project follows [Semantic Versioning v2.
 ## Unreleased - 2022-??-??
 ### Fixed
 - Fixed detector `DontUseFloatsAsLoopCounters` to prevent false positives. ([#2126](https://github.com/spotbugs/spotbugs/issues/2126))
+- Fixed detector `UncallableMethodOfAnonymousClass` to not report unused methods of method-local enumerations and records ([#2120](https://github.com/spotbugs/spotbugs/issues/2120))
 
 ## 4.7.2 - 2022-09-02
 ### Fixed

spotbugs-tests/src/test/java/edu/umd/cs/findbugs/detect/Issue2120Test.java

@@ -0,0 +1,32 @@
+package edu.umd.cs.findbugs.detect;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import edu.umd.cs.findbugs.AbstractIntegrationTest;
+import edu.umd.cs.findbugs.test.matcher.BugInstanceMatcher;
+import edu.umd.cs.findbugs.test.matcher.BugInstanceMatcherBuilder;
+
+import static edu.umd.cs.findbugs.test.CountMatcher.containsExactly;
+import static org.junit.Assume.assumeFalse;
+import static org.junit.Assume.assumeThat;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.number.OrderingComparison.greaterThanOrEqualTo;
+
+public class Issue2120Test extends AbstractIntegrationTest {
+    @Before
+    public void verifyJavaVersion() {
+        assumeFalse(System.getProperty("java.specification.version").startsWith("1."));
+        int javaVersion = Integer.parseInt(System.getProperty("java.specification.version"));
+        assumeThat(javaVersion, is(greaterThanOrEqualTo(11)));
+    }
+
+    @Test
+    public void test() {
+        performAnalysis("../java14/Issue2120.class");
+        BugInstanceMatcher matcher = new BugInstanceMatcherBuilder()
+                .bugType("UMAC_UNCALLABLE_METHOD_OF_ANONYMOUS_CLASS").build();
+        assertThat(getBugCollection(), containsExactly(0, matcher));
+    }
+}

spotbugs/src/main/java/edu/umd/cs/findbugs/detect/UncallableMethodOfAnonymousClass.java

@@ -59,6 +59,11 @@ public UncallableMethodOfAnonymousClass(BugReporter bugReporter) {
 
     @Override
     public void visitJavaClass(JavaClass obj) {
+        if (Values.DOTTED_JAVA_LANG_ENUM.equals(obj.getSuperclassName()) ||
+                Values.DOTTED_JAVA_LANG_RECORD.equals(obj.getSuperclassName())) {
+            return;
+        }
+
         try {
             obj.getSuperClass();
         } catch (ClassNotFoundException e) {

spotbugs/src/main/java/edu/umd/cs/findbugs/util/Values.java

@@ -54,6 +54,10 @@ public final class Values {
     @DottedClassName
     public static final String DOTTED_JAVA_LANG_STRINGBUFFER = "java.lang.StringBuffer";
     @DottedClassName
+    public static final String DOTTED_JAVA_LANG_ENUM = "java.lang.Enum";
+    @DottedClassName
+    public static final String DOTTED_JAVA_LANG_RECORD = "java.lang.Record";
+    @DottedClassName
     public static final String DOTTED_JAVA_IO_FILE = "java.io.File";
     @DottedClassName
     public static final String DOTTED_JAVA_NIO_PATH = "java.nio.file.Path";

spotbugsTestCases/src/java14/Issue2120.java

@@ -0,0 +1,12 @@
+public class Issue2120 {
+    static void method() {
+        record MyRecord(int from, int to) { /**/ }
+
+        enum MyEnum {
+            RED, BLUE;
+        }
+
+        System.out.println(new MyRecord(1, 2));
+        System.out.println(MyEnum.RED);
+    }
+}