Make RedundantModifier checks if enum constructor has redundant private

modifier, fixes part of #1242

src/main/java/com/puppycrawl/tools/checkstyle/api/JavadocTagInfo.java

@@ -432,7 +432,7 @@ public enum JavadocTagInfo {
      * @param name the tag name
      * @param type the type of tag
      */
-    private JavadocTagInfo(final String text, final String name,
+    JavadocTagInfo(final String text, final String name,
         final Type type) {
         this.text = text;
         this.name = name;

src/main/java/com/puppycrawl/tools/checkstyle/checks/LineSeparatorOption.java

@@ -51,7 +51,7 @@ public enum LineSeparatorOption {
      * Creates a new <code>LineSeparatorOption</code> instance.
      * @param sep the line separator, e.g. "\r\n"
      */
-    private LineSeparatorOption(String sep) {
+    LineSeparatorOption(String sep) {
         lineSeparator = sep.getBytes(StandardCharsets.US_ASCII);
     }
 

src/main/java/com/puppycrawl/tools/checkstyle/checks/modifier/RedundantModifierCheck.java

@@ -28,9 +28,11 @@ import com.puppycrawl.tools.checkstyle.api.TokenTypes;
 
 /**
  * Checks for redundant modifiers in interface and annotation definitions.
- * Also checks for redundant final modifiers on methods of final classes.
+ * Also checks for redundant final modifiers on methods of final classes
+ * and redundant enum constructor modifier.
  *
  * @author lkuehne
+ * @author <a href="mailto:piotr.listkiewicz@gmail.com">liscju</a>
  */
 public class RedundantModifierCheck
     extends Check {
@@ -56,6 +58,7 @@ public class RedundantModifierCheck
             TokenTypes.VARIABLE_DEF,
             TokenTypes.ANNOTATION_FIELD_DEF,
             TokenTypes.INTERFACE_DEF,
+            TokenTypes.CTOR_DEF,
         };
     }
 
@@ -71,23 +74,18 @@ public class RedundantModifierCheck
             TokenTypes.VARIABLE_DEF,
             TokenTypes.ANNOTATION_FIELD_DEF,
             TokenTypes.INTERFACE_DEF,
+            TokenTypes.CTOR_DEF,
         };
     }
 
     @Override
     public void visitToken(DetailAST ast) {
         if (TokenTypes.INTERFACE_DEF == ast.getType()) {
-            final DetailAST modifiers =
-                ast.findFirstToken(TokenTypes.MODIFIERS);
-
-            for (final int tokenType : TOKENS_FOR_INTERFACE_MODIFIERS) {
-                final DetailAST modifier =
-                        modifiers.findFirstToken(tokenType);
-                if (modifier != null) {
-                    log(modifier.getLineNo(), modifier.getColumnNo(),
-                            MSG_KEY, modifier.getText());
-                }
-            }
+            checkInterfaceModifiers(ast);
+        }
+        else if (TokenTypes.CTOR_DEF == ast.getType()
+                && isEnumMember(ast)) {
+            checkEnumConstructorModifiers(ast);
         }
         else if (isInterfaceOrAnnotationMember(ast)) {
             processInterfaceOrAnnotation(ast);
@@ -97,6 +95,37 @@ public class RedundantModifierCheck
         }
     }
 
+    /**
+     * Checks if interface has proper modifiers
+     * @param ast interface to check
+     */
+    private void checkInterfaceModifiers(DetailAST ast) {
+        final DetailAST modifiers =
+            ast.findFirstToken(TokenTypes.MODIFIERS);
+
+        for (final int tokenType : TOKENS_FOR_INTERFACE_MODIFIERS) {
+            final DetailAST modifier =
+                    modifiers.findFirstToken(tokenType);
+            if (modifier != null) {
+                log(modifier.getLineNo(), modifier.getColumnNo(),
+                        MSG_KEY, modifier.getText());
+            }
+        }
+    }
+
+    /**
+     * Check if enum constructor has proper modifiers
+     * @param ast constructor of enum
+     */
+    private void checkEnumConstructorModifiers(DetailAST ast) {
+        final DetailAST modifiers = ast.findFirstToken(TokenTypes.MODIFIERS);
+        final DetailAST modifier = modifiers.getFirstChild();
+        if (modifier != null) {
+            log(modifier.getLineNo(), modifier.getColumnNo(),
+                    MSG_KEY, modifier.getText());
+        }
+    }
+
     /**
      * do validation of interface of annotation
      * @param ast token AST
@@ -161,6 +190,16 @@ public class RedundantModifierCheck
         }
     }
 
+    /**
+     * Checks if current AST node is member of Enum
+     * @param ast AST node
+     * @return true if it is an enum member
+     */
+    private boolean isEnumMember(DetailAST ast) {
+        final DetailAST parentTypeDef = ast.getParent().getParent();
+        return parentTypeDef.getType() == TokenTypes.ENUM_DEF;
+    }
+
     /**
      * Checks if current AST node is member of Interface or Annotation, not of their subnodes.
      * @param ast AST node

src/test/java/com/puppycrawl/tools/checkstyle/checks/modifier/RedundantModifierTest.java

@@ -82,6 +82,16 @@ public class RedundantModifierTest
                 expected);
     }
 
+    @Test
+    public void testEnumConstructorIsImplicitlyPrivate() throws Exception {
+        final DefaultConfiguration checkConfig =
+                createCheckConfig(RedundantModifierCheck.class);
+        final String[] expected = {
+            "10:5: " + getCheckMessage(MSG_KEY, "private"),
+        };
+        verify(checkConfig, getPath("InputRedundantConstructorModifier.java"), expected);
+    }
+
     @Test
     public void testGetAcceptableTokens() {
         RedundantModifierCheck redundantModifierCheckObj = new RedundantModifierCheck();
@@ -91,6 +101,7 @@ public class RedundantModifierTest
             TokenTypes.VARIABLE_DEF,
             TokenTypes.ANNOTATION_FIELD_DEF,
             TokenTypes.INTERFACE_DEF,
+            TokenTypes.CTOR_DEF,
         };
         Assert.assertNotNull(actual);
         Assert.assertArrayEquals(expected, actual);

src/test/resources/com/puppycrawl/tools/checkstyle/InputRedundantConstructorModifier.java

@@ -0,0 +1,19 @@
+////////////////////////////////////////////////////////////////////////////////
+// Test case file for checkstyle.
+// Created: 2015
+////////////////////////////////////////////////////////////////////////////////
+package com.puppycrawl.tools.checkstyle;
+
+public enum InputRedundantConstructorModifier {
+    VAL1, VAL2;
+
+    private InputRedundantConstructorModifier() { }
+
+    InputRedundantConstructorModifier(int i) { }
+
+    InputRedundantConstructorModifier(char c) { }
+}
+
+class ProperPrivateConstructor {
+    private ProperPrivateConstructor() { }
+}