don't add the same comment over and over again. Related to PR 48558

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@902000 13f79535-47bb-0310-9956-ffa450edef68

WHATSNEW

@@ -20,6 +20,10 @@ Fixed bugs:
  * <scp> task didn't report build file location when a remote operation failed
    Bugzilla Report 48578.  
 
+ * <propertyfile> would add the same comment each time it updated an
+   existing property file.
+   Bugzilla Report 48558.
+
 Other changes:
 --------------
 

src/main/org/apache/tools/ant/util/LayoutPreservingProperties.java

@@ -259,8 +259,14 @@ public class LayoutPreservingProperties extends Properties {
         osw.write("#" + (new Date()).toString() + LS);
 
         boolean writtenSep = false;
-        for (Iterator i = logicalLines.iterator(); i.hasNext();) {
+        boolean maySkipComment = header != null;
+        for (Iterator i = logicalLines.iterator(); i.hasNext();
+             maySkipComment = false) {
             LogicalLine line = (LogicalLine) i.next();
+            if (maySkipComment && line instanceof Comment && 
+                header.equals(line.toString().substring(1))) {
+                continue;
+            }
             if (line instanceof Pair) {
                 if (((Pair)line).isNew()) {
                     if (!writtenSep) {

src/tests/antunit/taskdefs/optional/propertyfilelayout-test.xml

@@ -26,13 +26,16 @@ foo=bar
 #second comment
 x=1
 ]]></echo>
+    <presetdef name="pf">
+      <propertyfile file="${output}/created.properties">
+        <entry key="foo" value="bar"/>
+        <entry key="x" value="1" type="int"/>
+      </propertyfile>
+    </presetdef>
   </target>
 
   <target name="testCreateWithoutComment" depends="setUp">
-    <propertyfile file="${output}/created.properties">
-      <entry key="foo" value="bar"/>
-      <entry key="x" value="1" type="int"/>
-    </propertyfile>
+    <pf/>
     <local name="head.in"/>
     <local name="head.out"/>
     <local name="tail.in"/>
@@ -64,10 +67,7 @@ x=1
   </target>
 
   <target name="testCreateWithComment" depends="setUp">
-    <propertyfile file="${output}/created.properties" comment="my comment">
-      <entry key="foo" value="bar"/>
-      <entry key="x" value="1" type="int"/>
-    </propertyfile>
+    <pf comment="my comment"/>
     <local name="head.in"/>
     <local name="head.out"/>
     <local name="middle.in"/>
@@ -113,4 +113,81 @@ x=1
     <au:assertPropertyEquals name="tail.out" value="${tail.in}"/>
   </target>
 
+  <target name="-updateSetUp" depends="setUp">
+    <copy file="${input}/initial.properties"
+          tofile="${output}/created.properties"/>
+  </target>
+
+  <target name="testUpdateWithoutComment" depends="-updateSetUp">
+    <pf/>
+    <local name="head.in"/>
+    <local name="head.out"/>
+    <loadfile srcfile="${input}/initial.properties" property="head.in"/>
+    <!-- skip date -->
+    <loadfile srcfile="${output}/created.properties" property="head.out">
+      <filterchain>
+        <headfilter skip="1"/>
+      </filterchain>
+    </loadfile>
+    <au:assertPropertyEquals name="head.out" value="${head.in}"/>
+  </target>
+
+  <target name="testUpdateWithNewComment" depends="-updateSetUp">
+    <pf comment="new comment"/>
+    <local name="head.in"/>
+    <local name="head.out"/>
+    <local name="tail.in"/>
+    <local name="tail.out"/>
+    <property name="head.in" value="#new comment${line.separator}"/>
+    <!-- just comment -->
+    <loadfile srcfile="${output}/created.properties" property="head.out">
+      <filterchain>
+        <headfilter lines="1"/>
+      </filterchain>
+    </loadfile>
+    <loadfile srcfile="${input}/initial.properties" property="tail.in"/>
+    <!-- skip new comment and date -->
+    <loadfile srcfile="${output}/created.properties" property="tail.out">
+      <filterchain>
+        <headfilter skip="2"/>
+      </filterchain>
+    </loadfile>
+    <au:assertPropertyEquals name="head.out" value="${head.in}"/>
+    <au:assertPropertyEquals name="tail.out" value="${tail.in}"/>
+  </target>
+
+  <target name="testUpdateWithSameComment" depends="-updateSetUp">
+    <pf comment="my comment"/>
+    <local name="head.in"/>
+    <local name="head.out"/>
+    <local name="tail.in"/>
+    <local name="tail.out"/>
+    <!-- just comment -->
+    <loadfile srcfile="${input}/initial.properties" property="head.in">
+      <filterchain>
+        <headfilter lines="1"/>
+      </filterchain>
+    </loadfile>
+    <!-- just comment -->
+    <loadfile srcfile="${output}/created.properties" property="head.out">
+      <filterchain>
+        <headfilter lines="1"/>
+      </filterchain>
+    </loadfile>
+    <!-- skip comment -->
+    <loadfile srcfile="${input}/initial.properties" property="tail.in">
+      <filterchain>
+        <headfilter skip="1"/>
+      </filterchain>
+    </loadfile>
+    <!-- skip comment and date -->
+    <loadfile srcfile="${output}/created.properties" property="tail.out">
+      <filterchain>
+        <headfilter skip="2"/>
+      </filterchain>
+    </loadfile>
+    <au:assertPropertyEquals name="head.out" value="${head.in}"/>
+    <au:assertPropertyEquals name="tail.out" value="${tail.in}"/>
+  </target>
+
 </project>