Solution to wrong variable reported because of name shadowing in FinalLocalVariableCheck. solves #1142

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

@@ -159,8 +159,9 @@ public class FinalLocalVariableCheck extends Check {
                 }
             case TokenTypes.VARIABLE_DEF:
                 if (ast.getParent().getType() != TokenTypes.OBJBLOCK
-                    && shouldCheckEnhancedForLoopVariable(ast)
-                    && isVariableInForInit(ast)) {
+                        && shouldCheckEnhancedForLoopVariable(ast)
+                        && isVariableInForInit(ast)
+                        && !ast.branchContains(TokenTypes.FINAL)) {
                     insertVariable(ast);
                 }
                 break;
@@ -255,16 +256,48 @@ public class FinalLocalVariableCheck extends Check {
         return paramDef.getParent().getParent().getType() == TokenTypes.LAMBDA;
     }
 
+    /**
+     * Find the Class or Method in which it is defined.
+     * @param ast Variable for which we want to find the scope in which it is defined
+     * @return ast The Class or Method in which it is defined.
+     */
+    private static DetailAST findClassOrMethodInWhichItIsDefined(DetailAST ast) {
+        DetailAST astTraverse = ast;
+        while (!(astTraverse.getType() == TokenTypes.METHOD_DEF
+                || astTraverse.getType() == TokenTypes.CLASS_DEF)) {
+            astTraverse = astTraverse.getParent();
+        }
+        return astTraverse;
+    }
+
+    /**
+     * Check if both the Variable are same.
+     * @param ast1 Variable to compare
+     * @param ast2 Variable to compare
+     * @return true if both the variable are same, otherwise false
+     */
+    private static boolean isSameVariables(DetailAST ast1, DetailAST ast2) {
+        final DetailAST classOrMethodOfAst1 =
+            findClassOrMethodInWhichItIsDefined(ast1);
+        final DetailAST classOrMethodOfAst2 =
+            findClassOrMethodInWhichItIsDefined(ast2);
+
+        final String identifierOfAst1 =
+            classOrMethodOfAst1.findFirstToken(TokenTypes.IDENT).getText();
+        final String identifierOfAst2 =
+            classOrMethodOfAst2.findFirstToken(TokenTypes.IDENT).getText();
+
+        return identifierOfAst1.equals(identifierOfAst2);
+    }
+
     /**
      * Inserts a variable at the topmost scope stack
      * @param ast the variable to insert
      */
     private void insertVariable(DetailAST ast) {
-        if (!ast.branchContains(TokenTypes.FINAL)) {
-            final Map<String, DetailAST> state = scopeStack.peek();
-            final DetailAST astNode = ast.findFirstToken(TokenTypes.IDENT);
-            state.put(astNode.getText(), astNode);
-        }
+        final Map<String, DetailAST> state = scopeStack.peek();
+        final DetailAST astNode = ast.findFirstToken(TokenTypes.IDENT);
+        state.put(astNode.getText(), astNode);
     }
 
     /**
@@ -275,8 +308,9 @@ public class FinalLocalVariableCheck extends Check {
         final Iterator<Map<String, DetailAST>> iterator = scopeStack.descendingIterator();
         while (iterator.hasNext()) {
             final Map<String, DetailAST> state = iterator.next();
-            final Object obj = state.remove(ast.getText());
-            if (obj != null) {
+            final DetailAST storedVariable = state.get(ast.getText());
+            if (storedVariable != null && isSameVariables(storedVariable, ast)) {
+                state.remove(ast.getText());
                 break;
             }
         }

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

@@ -131,4 +131,18 @@ public class FinalLocalVariableCheckTest
                 + "tools/checkstyle/naming/InputFinalLocalVariableNameLambda.java")
                 .getCanonicalPath(), expected);
     }
+
+    @Test
+    public void testVariableNameShadowing()
+        throws Exception {
+        final DefaultConfiguration checkConfig =
+            createCheckConfig(FinalLocalVariableCheck.class);
+        checkConfig.addAttribute("tokens", "PARAMETER_DEF,VARIABLE_DEF");
+
+        final String[] expected = {
+            "4:28: " + "Variable 'text' should be declared final.",
+            "17:13: " + "Variable 'x' should be declared final.",
+        };
+        verify(checkConfig, getPath("coding/InputFinalLocalVariableNameShadowing.java"), expected);
+    }
 }

src/test/resources/com/puppycrawl/tools/checkstyle/coding/InputFinalLocalVariableNameShadowing.java

@@ -0,0 +1,26 @@
+package com.puppycrawl.tools.checkstyle.coding;
+
+class Foo1 {
+    public void foo(String text) {
+        System.out.println(text);
+
+        class Bar {
+            void bar (String text) {
+                text = "xxx";
+            }
+        }
+    }
+}
+
+class Foo2 {
+    public void foo() {
+        int x;
+        class Bar {
+            void bar () {
+                int x = 1;
+                x++;
+                x++;
+            }
+        }
+    }
+}