Bug 314576: added assignment to itself checker, contribution from Severin Gehwolf

codan/org.eclipse.cdt.codan.checkers/OSGI-INF/l10n/bundle.properties

@@ -45,3 +45,7 @@ problem.name.UnusedReturnValue = Unused return value
 problem.description.NoReturn = No return statement in a function which is declared to return value
 problem.messagePattern.NoReturn = No return, in function returning non-void
 problem.name.NoReturn = No return
+checker.name.AssignmentToItself = Assignment to itself
+problem.messagePattern.AssignmentToItself = Assignment to itself ''{0}''
+problem.name.AssignmentToItself = Assignment to itself
+problem.description.AssignmentToItself = Finds expression where left and right side of the assignment is the same, i.e. 'var = var'

codan/org.eclipse.cdt.codan.checkers/plugin.xml

@@ -250,5 +250,19 @@
                       name="Field cannot be resolved">
                 </problem>
              </checker>
+             <checker
+		            class="org.eclipse.cdt.codan.internal.checkers.AssignmentToItselfChecker"
+		            id="org.eclipse.cdt.codan.internal.checkers.AssignmentToItselfChecker"
+		            name="%checker.name.AssignmentToItself">
+		     	<problem
+              category="org.eclipse.cdt.codan.core.categories.ProgrammingProblems"
+              defaultEnabled="true"
+              defaultSeverity="Error"
+              description="%problem.description.AssignmentToItself"
+              id="org.eclipse.cdt.codan.internal.checkers.AssignmentToItselfProblem"
+              messagePattern="%problem.messagePattern.AssignmentToItself"
+              name="%problem.name.AssignmentToItself">
+		      	</problem>
+		     </checker>
    </extension>
 </plugin>

codan/org.eclipse.cdt.codan.checkers/src/org/eclipse/cdt/codan/internal/checkers/AssignmentToItselfChecker.java

@@ -0,0 +1,54 @@
+/*******************************************************************************
+ * Copyright (c) 2010 Severin Gehwolf 
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Severin Gehwolf  - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.codan.internal.checkers;
+
+import org.eclipse.cdt.codan.core.cxx.model.AbstractIndexAstChecker;
+import org.eclipse.cdt.core.dom.ast.ASTVisitor;
+import org.eclipse.cdt.core.dom.ast.IASTBinaryExpression;
+import org.eclipse.cdt.core.dom.ast.IASTExpression;
+import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit;
+
+/**
+ * Checker that find assignment to itself cases, such a
+ * a = a. It can produce some false positives such as
+ * a[f()]=a[f()] - but who write codes like that?
+ */
+public class AssignmentToItselfChecker extends AbstractIndexAstChecker {
+
+	private static final String ER_ID = "org.eclipse.cdt.codan.internal.checkers.AssignmentToItselfProblem"; //$NON-NLS-1$
+	
+	public void processAst(IASTTranslationUnit ast) {
+		// traverse the ast using the visitor pattern.
+		ast.accept(new ASTVisitor() {
+			{ // constructor
+				shouldVisitExpressions = true;
+			}
+			
+			// visit expressions
+			public int visit(IASTExpression expression) {
+				if (isAssignmentToItself(expression)) {
+					reportProblem(ER_ID, expression, expression.getRawSignature());
+				}
+				return PROCESS_CONTINUE;
+			}
+			
+			private boolean isAssignmentToItself(IASTExpression e) {
+				if (e instanceof IASTBinaryExpression) {
+					IASTBinaryExpression binExpr = (IASTBinaryExpression) e;
+					if (binExpr.getOperator() == IASTBinaryExpression.op_assign) {
+						return binExpr.getOperand1().getRawSignature().equals(binExpr.getOperand2().getRawSignature());
+					}
+				}
+				return false;
+			}
+		});
+	}
+}

codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/internal/checkers/AssignmentToItselfCheckerTest.java

@@ -0,0 +1,57 @@
+/*******************************************************************************
+ * Copyright (c) 2010 Severin Gehwolf 
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Severin Gehwolf  - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.codan.core.internal.checkers;
+
+import org.eclipse.cdt.codan.core.test.CheckerTestCase;
+
+/**
+ * Test for {@see AssignmentToItselfChecker} class
+ * 
+ */
+public class AssignmentToItselfCheckerTest extends CheckerTestCase {
+	// void main() {
+	// int x = 0;
+	// x = 10;
+	// }
+	public void testNoErrorConstants() {
+		loadCodeAndRun(getAboveComment());
+		checkNoErrors();
+	}
+
+	// void main() {
+	// int x = 10;
+	// int s = 10;
+	// x = s;
+	// }
+	public void testNoErrorVariables() {
+		loadCodeAndRun(getAboveComment());
+		checkNoErrors();
+	}
+
+	// void main() {
+	// int x = 0;
+	// x = x;
+	// }
+	public void testSimpleVariableSelfAssignmentError() {
+		loadCodeAndRun(getAboveComment());
+		checkErrorLine(3);
+	}
+
+	// void main() {
+	// char str[] = "hello testing world";
+	// int x = 10;
+	// str[i] = str[i];
+	// }
+	public void testArraySelfAssignmentError() {
+		loadCodeAndRun(getAboveComment());
+		checkErrorLine(4);
+	}
+}

codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/test/AutomatedIntegrationSuite.java

@@ -15,6 +15,7 @@ import junit.framework.Test;
 import junit.framework.TestSuite;
 
 import org.eclipse.cdt.codan.core.internal.checkers.AssignmentInConditionCheckerTest;
+import org.eclipse.cdt.codan.core.internal.checkers.AssignmentToItselfCheckerTest;
 import org.eclipse.cdt.codan.core.internal.checkers.CatchByReferenceTest;
 import org.eclipse.cdt.codan.core.internal.checkers.ReturnCheckerTest;
 import org.eclipse.cdt.codan.core.internal.checkers.StatementHasNoEffectCheckerTest;
@@ -45,6 +46,7 @@ public class AutomatedIntegrationSuite extends TestSuite {
 		suite.addTestSuite(ReturnCheckerTest.class);
 		suite.addTestSuite(CatchByReferenceTest.class);
 		suite.addTestSuite(AssignmentInConditionCheckerTest.class);
+		suite.addTestSuite(AssignmentToItselfCheckerTest.class);
 		// framework
 		suite.addTest(CodanFastTestSuite.suite());
 		// quick fixes