unused: search for main in inner classes (IDEA-178721)

java/java-analysis-impl/src/com/intellij/codeInspection/deadCode/UnusedDeclarationInspectionBase.java

@@ -400,7 +400,9 @@ public class UnusedDeclarationInspectionBase extends GlobalInspectionTool {
       if (isAddServletEnabled() && servlet != null && aClass.isInheritor(servlet, true)) {
         return true;
       }
-      if (isAddMainsEnabled() && PsiMethodUtil.hasMainMethod(aClass)) return true;
+      if (isAddMainsEnabled()) {
+        if (hasMainMethodDeep(aClass)) return true;
+      }
     }
     if (element instanceof PsiModifierListOwner) {
       final EntryPointsManager entryPointsManager = EntryPointsManager.getInstance(project);
@@ -414,6 +416,16 @@ public class UnusedDeclarationInspectionBase extends GlobalInspectionTool {
     return RefUtil.isImplicitUsage(element);
   }
 
+  private static boolean hasMainMethodDeep(PsiClass aClass) {
+    if (PsiMethodUtil.hasMainMethod(aClass)) return true;
+    for (PsiClass innerClass : aClass.getInnerClasses()) {
+      if (innerClass.hasModifierProperty(PsiModifier.STATIC) && PsiMethodUtil.hasMainMethod(innerClass)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
   public boolean isGlobalEnabledInEditor() {
     return myEnabledInEditor;
   }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/unusedDecls/InnerClassWithMainMethod.java

@@ -0,0 +1,7 @@
+class Test {
+    static class NestedTest {
+        public static void main(String[] args) {
+            new Test();
+        }
+    }
+}

java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/UnusedSymbolLocalTest.java

@@ -35,6 +35,7 @@ public class UnusedSymbolLocalTest extends DaemonAnalyzerTestCase {
   }
 
   public void testInnerClass() throws Exception { doTest(); }
+  public void testInnerClassWithMainMethod() throws Exception { doTest(); }
   public void testInnerUsesSelf() throws Exception { doTest(); }
   public void testLocalClass() throws Exception { doTest(); }
   public void testPrivateConstructor() throws Exception { doTest(); }