Issue #382: Fix HiddenField false positive violations for anonymous classes

src/main/java/com/puppycrawl/tools/checkstyle/checks/coding/HiddenFieldCheck.java

@@ -27,6 +27,7 @@ import java.util.regex.Pattern;
 import com.google.common.collect.Sets;
 import com.puppycrawl.tools.checkstyle.api.Check;
 import com.puppycrawl.tools.checkstyle.api.DetailAST;
+import com.puppycrawl.tools.checkstyle.api.Scope;
 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
 import com.puppycrawl.tools.checkstyle.utils.CommonUtils;
 import com.puppycrawl.tools.checkstyle.utils.ScopeUtils;
@@ -280,16 +281,38 @@ public class HiddenFieldCheck
             final DetailAST nameAST = ast.findFirstToken(TokenTypes.IDENT);
             final String name = nameAST.getText();
 
-            if (isStaticOrInstanceField(ast, name)
-                && !isMatchingRegexp(name)
-                && !isIgnoredSetterParam(ast, name)
-                && !isIgnoredConstructorParam(ast)
-                && !isIgnoredParamOfAbstractMethod(ast)) {
+            if ((isStaticFieldHiddenFromAnonymousClass(ast, name)
+                        || isStaticOrInstanceField(ast, name))
+                    && !isMatchingRegexp(name)
+                    && !isIgnoredParam(ast, name)) {
                 log(nameAST, MSG_KEY, name);
             }
         }
     }
 
+    /**
+     * Checks whether a static field is hidden from closure.
+     * @param nameAST local variable or parameter.
+     * @param name field name.
+     * @return true if static field is hidden from closure.
+     */
+    private boolean isStaticFieldHiddenFromAnonymousClass(DetailAST nameAST, String name) {
+        return isInStatic(nameAST)
+            && frame.containsStaticField(name);
+    }
+
+    /**
+     * Checks whether method or constructor parameter is ignored.
+     * @param ast the parameter token.
+     * @param name the parameter name.
+     * @return true if parameter is ignored.
+     */
+    private boolean isIgnoredParam(DetailAST ast, String name) {
+        return isIgnoredSetterParam(ast, name)
+            || isIgnoredConstructorParam(ast)
+            || isIgnoredParamOfAbstractMethod(ast);
+    }
+
     /**
      * Check for static or instance field.
      * @param ast token
@@ -324,7 +347,9 @@ public class HiddenFieldCheck
             if (parent.getType() == TokenTypes.STATIC_INIT) {
                 inStatic = true;
             }
-            else if (parent.getType() == TokenTypes.METHOD_DEF) {
+            else if (parent.getType() == TokenTypes.METHOD_DEF
+                        && !ScopeUtils.isInScope(parent, Scope.ANONINNER)
+                        || parent.getType() == TokenTypes.VARIABLE_DEF) {
                 final DetailAST mods =
                     parent.findFirstToken(TokenTypes.MODIFIERS);
                 inStatic = mods.branchContains(TokenTypes.LITERAL_STATIC);

src/main/java/com/puppycrawl/tools/checkstyle/utils/ScopeUtils.java

@@ -265,4 +265,15 @@ public final class ScopeUtils {
         }
         return localVariableDef;
     }
+
+    /**
+     * Checks whether ast node is in a specific scope.
+     * @param ast the node to check.
+     * @param scope a {@code Scope} value.
+     * @return true if the ast node is in the scope.
+     */
+    public static boolean isInScope(DetailAST ast, Scope scope) {
+        final Scope surroundingScopeOfAstToken = getSurroundingScope(ast);
+        return surroundingScopeOfAstToken == scope;
+    }
 }

src/test/java/com/puppycrawl/tools/checkstyle/checks/coding/HiddenFieldCheckTest.java

@@ -29,6 +29,21 @@ import com.puppycrawl.tools.checkstyle.DefaultConfiguration;
 
 public class HiddenFieldCheckTest
     extends BaseCheckTestSupport {
+
+    @Test
+    public void testStaticVisibilityFromAnonymousClasses() throws Exception {
+        final DefaultConfiguration checkConfig =
+            createCheckConfig(HiddenFieldCheck.class);
+        final String[] expected = {
+            "10:95: " + getCheckMessage(MSG_KEY, "other"),
+            "16:92: " + getCheckMessage(MSG_KEY, "other"),
+            "24:99: " + getCheckMessage(MSG_KEY, "other"),
+            "34:103: " + getCheckMessage(MSG_KEY, "other"),
+            "46:26: " + getCheckMessage(MSG_KEY, "someField"),
+        };
+        verify(checkConfig, getPath("InputHidenFieldStaticVisibility.java"), expected);
+    }
+
     @Test
     public void testNoParameters()
         throws Exception {

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

@@ -0,0 +1,47 @@
+package com.puppycrawl.tools.checkstyle;
+
+import java.util.Comparator;
+
+public class InputHidenFieldStaticVisibility {
+    static int someField;
+    static InputHidenFieldStaticVisibility other = null;
+    InputHidenFieldStaticVisibility field = null;
+
+    static void method(InputHidenFieldStaticVisibility field, InputHidenFieldStaticVisibility other) {
+        // field 'field' can not be referenced form a static context
+        // static field 'other' can be referenced from a static context
+    }
+
+    static class B {
+        void method(InputHidenFieldStaticVisibility field, InputHidenFieldStaticVisibility other) {
+            // field 'field' can not be referenced form a static context
+            // static field 'other' can be referenced from a static context
+        }
+    }
+
+    static Comparator<InputHidenFieldStaticVisibility> COMP = new Comparator<InputHidenFieldStaticVisibility>() {
+        @Override
+        public int compare(InputHidenFieldStaticVisibility field, InputHidenFieldStaticVisibility other) {
+            // field 'field' can not be referenced form a static context
+            // static field 'other' can be referenced from a static context
+            return 0;
+        }
+    };
+
+    static Comparator<InputHidenFieldStaticVisibility> createComp() {
+        return new Comparator<InputHidenFieldStaticVisibility>() {
+            @Override
+            public int compare(InputHidenFieldStaticVisibility field, InputHidenFieldStaticVisibility other) {
+                // field 'field' can not be referenced form a static context
+                // static field 'other' can be referenced from a static context
+                return 0;
+            }
+        };
+    }
+
+    static void foo1(int a) {}
+
+    void foo2(int a) {}
+
+    static void foo3(int someField) {}
+}