merged from 4.2 branch: Fixed bug 2002722 - false + in UseStringBufferForStringAppends

git-svn-id: https://pmd.svn.sourceforge.net/svnroot/pmd/trunk@6335 51baf565-9d33-0410-a72c-fc3788e3496d

pmd/etc/changelog.txt

@@ -343,6 +343,7 @@ Fixed bug 1988829 - Violation reported without source file name (actually a fix
 Fixed bug 1989814 - false +: ConsecutiveLiteralAppends
 Fixed bug 1977230 - false positive: UselessOverridingMethod
 Fixed bug 1998185 - BeanMembersShouldSerialize vs @SuppressWarnings("serial")
+Fixed bug 2002722 - false + in UseStringBufferForStringAppends
 ruleset.dtd and ruleset_xml_schema.xsd added to jar file in rulesets directory
 bin and java14/bin scripts:
 	retroweaver version was not correct in java14/bin scripts

pmd/regress/test/net/sourceforge/pmd/rules/optimizations/xml/UseStringBufferForStringAppends.xml

@@ -99,6 +99,38 @@ public class Foo{
         for (int i = 0; i < 10; i++){
         result = result + i;
         } }
+}
+     ]]></code>
+    </test-code>
+    <test-code>
+        <description><![CDATA[
+false positive bug #2002722
+     ]]></description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public class Foo {
+  void bar() {
+    String dtdColumnNames[] = null;
+    String sortedDtdColumns[] = null;
+    final int loop = 0;
+    dtdColumnNames[loop] = dtdColumnNames[loop].trim ( );
+    sortedDtdColumns[loop] = sortedDtdColumns[loop].trim ( );
+  }
+}
+     ]]></code>
+    </test-code>
+    <test-code>
+        <description><![CDATA[
+false positive bug #2002722, different bug in comment section
+     ]]></description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public class Foo {
+  void bar2() {
+    String foo ="foo";
+    foo = mangleTheInput(foo);
+  }
+  String mangleTheInput(final String s) { return s;}
 }
      ]]></code>
     </test-code>

pmd/src/net/sourceforge/pmd/lang/java/rule/optimizations/UseStringBufferForStringAppendsRule.java

@@ -1,6 +1,7 @@
 package net.sourceforge.pmd.lang.java.rule.optimizations;
 
 import net.sourceforge.pmd.lang.ast.Node;
+import net.sourceforge.pmd.lang.java.ast.ASTArgumentList;
 import net.sourceforge.pmd.lang.java.ast.ASTAssignmentOperator;
 import net.sourceforge.pmd.lang.java.ast.ASTLocalVariableDeclaration;
 import net.sourceforge.pmd.lang.java.ast.ASTName;
@@ -15,7 +16,7 @@ public class UseStringBufferForStringAppendsRule extends AbstractJavaRule {
 
     @Override
     public Object visit(ASTVariableDeclaratorId node, Object data) {
-        if (!TypeHelper.isA(node, String.class)) {
+        if (!TypeHelper.isA(node, String.class) || node.isArray()) {
             return data;
         }
         Node parent = node.jjtGetParent().jjtGetParent();
@@ -28,6 +29,11 @@ public class UseStringBufferForStringAppendsRule extends AbstractJavaRule {
             if (statement == null) {
                 continue;
             }
+            ASTArgumentList argList = name.getFirstParentOfType(ASTArgumentList.class);
+            if (argList != null && argList.getFirstParentOfType(ASTStatementExpression.class) == statement) {
+                // used in method call
+                continue;
+            }
             if (statement.jjtGetNumChildren() > 0 && statement.jjtGetChild(0).getClass().equals(ASTPrimaryExpression.class)) {
                 ASTName astName = statement.jjtGetChild(0).getFirstDescendantOfType(ASTName.class);
                 if(astName != null){