From 616efc5cd701fd4e69888e9f918658f1358aaaba Mon Sep 17 00:00:00 2001
From: Ankit Jain <radical@corewars.org>
Date: Mon, 28 Feb 2011 00:32:50 +0530
Subject: [PATCH] [xbuild] Remove property if Output TaskParameter is null.

If the TaskParameter for Output of a task is null, then remove
the corresponding property.
Add relevant test.
---
 .../Microsoft.Build.BuildEngine/TaskEngine.cs | 12 ++++--
 .../CreatePropertyTest.cs                     | 40 +++++++++++++++++++
 2 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/mcs/class/Microsoft.Build.Engine/Microsoft.Build.BuildEngine/TaskEngine.cs b/mcs/class/Microsoft.Build.Engine/Microsoft.Build.BuildEngine/TaskEngine.cs
index e0ddc933326..ef9a1afdf96 100644
--- a/mcs/class/Microsoft.Build.Engine/Microsoft.Build.BuildEngine/TaskEngine.cs
+++ b/mcs/class/Microsoft.Build.Engine/Microsoft.Build.BuildEngine/TaskEngine.cs
@@ -177,10 +177,6 @@ namespace Microsoft.Build.BuildEngine {
 					throw new InvalidProjectFileException ("This is not output property.");
 				
 				o = propertyInfo.GetValue (task, null);
-				// FIXME: maybe we should throw an exception here?
-				if (o == null)
-					continue;
-				
 				if (itemName != String.Empty) {
 					PublishItemGroup (propertyInfo, o, itemName);
 				} else {
@@ -198,6 +194,11 @@ namespace Microsoft.Build.BuildEngine {
 					      object o,
 					      string propertyName)
 		{
+			if (o == null) {
+				parentProject.EvaluatedProperties.RemoveProperty (propertyName);
+				return;
+			}
+
 			BuildProperty bp;
 			try {
 				bp = ChangeType.ToBuildProperty (o, propertyInfo.PropertyType, propertyName);
@@ -214,6 +215,9 @@ namespace Microsoft.Build.BuildEngine {
 					       object o,
 					       string itemName)
 		{
+			if (o == null)
+				return;
+
 			BuildItemGroup newItems;
 			try {
 				newItems = ChangeType.ToBuildItemGroup (o, propertyInfo.PropertyType, itemName);
diff --git a/mcs/class/Microsoft.Build.Tasks/Test/Microsoft.Build.Tasks/CreatePropertyTest.cs b/mcs/class/Microsoft.Build.Tasks/Test/Microsoft.Build.Tasks/CreatePropertyTest.cs
index 8b68c7dc971..543c3fd0448 100644
--- a/mcs/class/Microsoft.Build.Tasks/Test/Microsoft.Build.Tasks/CreatePropertyTest.cs
+++ b/mcs/class/Microsoft.Build.Tasks/Test/Microsoft.Build.Tasks/CreatePropertyTest.cs
@@ -127,5 +127,45 @@ namespace MonoTests.Microsoft.Build.Tasks {
 			Assert.AreEqual ("@(IG)", project.EvaluatedProperties["C"].FinalValue, "A6");
 		}
 
+		[Test]
+		public void TestEmptyPropertyValue ()
+		{
+			Engine engine;
+			Project project;
+
+			string documentString = @"
+                                <Project xmlns=""http://schemas.microsoft.com/developer/msbuild/2003"">
+					<PropertyGroup>
+						<A>1</A>
+					</PropertyGroup>
+					<Target Name='1'>
+						<Message Text='Before: $(A)'/>
+						<CreateProperty Value=''>
+							<Output
+								TaskParameter='Value'
+								PropertyName='A'
+							/>
+						</CreateProperty>
+						<Message Text='After: $(A)'/>
+					</Target>
+				</Project>
+			";
+
+			engine = new Engine (Consts.BinPath);
+
+			TestMessageLogger testLogger = new TestMessageLogger ();
+			engine.RegisterLogger (testLogger);
+
+			project = engine.CreateNewProject ();
+			project.LoadXml (documentString);
+			if (!project.Build ("1")) {
+				testLogger.DumpMessages ();
+				Assert.Fail ("Build failed");
+			}
+
+			testLogger.CheckLoggedMessageHead ("Before: 1", "A1");
+			testLogger.CheckLoggedMessageHead ("After: ", "A2");
+			Assert.AreEqual (0, testLogger.NormalMessageCount, "Unexpected messages found");
+		}
 	}
 }
-- 
2.25.1