[msbuild] Add support for the 'overwrite' metadata for PartialAppManifest items.

docs/build-apps/build-items.md

@@ -9,6 +9,42 @@ ms.date: 09/19/2024
 Build items control how .NET for iOS, Mac Catalyst, macOS, and tvOS
 application or library projects are built.
 
+## PartialAppManifest
+
+`PartialAppManifest` can be used to add additional partial app manifests that
+will be merged with the main app manifest (Info.plist).
+
+Any values in the partial app manifests will override values in the main app
+manifest unless the `Overwrite` metadata is set to `false`.
+
+If the same value is specified in multiple partial app manifests, it's
+undetermined which one will be the one used.
+
+```xml
+<ItemGroup>
+    <PartialAppManifest Include="my-partial-manifest.plist" Overwrite="false" />
+</ItemGroup>
+```
+
+If the developer needs to execute a target to compute what to add to the
+`PartialAppManifest` item group, it's possible to make sure this target is
+executed before the `PartialAppManifest` items are procesed by adding it to
+the `CollectAppManifestsDependsOn` property:
+
+```xml
+<PropertyGroup>
+    <CollectAppManifestsDependsOn>
+        AddPartialAppManifests;
+        $(CollectAppManifestsDependsOn);
+    </CollectAppManifestsDependsOn>
+</PropertyGroup>
+<Target Name="AddPartialAppManifests">
+    <ItemGroup>
+        <PartialAppManifest Include="MyPartialAppManifest.plist" />
+    </ItemGroup>
+</Target>
+```
+
 ## XcodeProject
 
 `<XcodeProject>` can be used to build and consume the outputs

msbuild/Xamarin.MacDev.Tasks/Tasks/CompileAppManifest.cs

@@ -393,15 +393,17 @@ protected void SetValue (PDictionary dict, string key, string value)
 				dict [key] = value;
 		}
 
-		public static void MergePartialPlistDictionary (PDictionary plist, PDictionary partial)
+		public static void MergePartialPlistDictionary (PDictionary plist, PDictionary partial, bool overwrite)
 		{
 			foreach (var property in partial) {
 				var key = property.Key!;
 				if (plist.ContainsKey (key)) {
+					if (!overwrite)
+						continue;
 					var value = plist [key];
 
 					if (value is PDictionary && property.Value is PDictionary) {
-						MergePartialPlistDictionary ((PDictionary) value, (PDictionary) property.Value);
+						MergePartialPlistDictionary ((PDictionary) value, (PDictionary) property.Value, overwrite);
 					} else {
 						plist [key] = property.Value.Clone ();
 					}
@@ -418,6 +420,7 @@ public static void MergePartialPLists (Task task, PDictionary plist, IEnumerable
 
 			foreach (var template in partialLists) {
 				PDictionary partial;
+				var overwrite = !string.Equals (template.GetMetadata ("Overwrite"), "false", StringComparison.OrdinalIgnoreCase);
 
 				try {
 					partial = PDictionary.FromFile (template.ItemSpec)!;
@@ -426,7 +429,7 @@ public static void MergePartialPLists (Task task, PDictionary plist, IEnumerable
 					continue;
 				}
 
-				MergePartialPlistDictionary (plist, partial);
+				MergePartialPlistDictionary (plist, partial, overwrite);
 			}
 		}
 

msbuild/Xamarin.Shared/Xamarin.Shared.targets

@@ -509,7 +509,7 @@ Copyright (C) 2018 Microsoft. All rights reserved.
 		      property to run targets that add to the `PartialAppManifest` item group before we process them.
 		    * Some MSBuild properties can also add values.
 
-		    The precedence is: MSBuild properties can be overridden by the Info.plist, which can be overridden by a partial plist.
+		    The precedence is: MSBuild properties can be overridden by the Info.plist, which can be overridden by a partial plist (a partial plist can also specify the "Overwrite=false" metadata to not overwrite any existing entries).
 
 		2. In the `CompileAppManifest` target we get all the inputs from above, and compute a temporary app manifest, which is written to a temporary output file.
 

tests/msbuild/Xamarin.MacDev.Tasks.Tests/TaskTests/CompileAppManifestTaskTests.cs

@@ -77,6 +77,36 @@ public void MultipleMinimumOSVersions ()
 			Assert.AreEqual ("13.0", plist.GetMinimumOSVersion (), "MinimumOSVersion");
 		}
 
+		[Test]
+		[TestCase (false, "14.0")]
+		[TestCase (true, "13.0")]
+		public void MultipleMinimumOSVersions_Overwrite (bool overwrite, string expectedMinimumOSVersion)
+		{
+			var dir = Cache.CreateTemporaryDirectory ();
+			var task = CreateTask (dir);
+
+			var mainPath = Path.Combine (dir, "Info.plist");
+			var main = new PDictionary ();
+			main.SetMinimumOSVersion ("14.0");
+			main.Save (mainPath);
+
+			var partialPath = Path.Combine (dir, "PartialAppManifest.plist");
+			var partial = new PDictionary ();
+			partial.SetMinimumOSVersion ("13.0");
+			partial.Save (partialPath);
+
+			task.AppManifest = new TaskItem (mainPath);
+			var partialAppManifest = new TaskItem (partialPath);
+			partialAppManifest.SetMetadata ("Overwrite", overwrite ? "true" : "false");
+			task.PartialAppManifests = new [] { partialAppManifest };
+			task.SupportedOSPlatformVersion = "14.0";
+
+			ExecuteTask (task);
+
+			var plist = PDictionary.FromFile (task.CompiledAppManifest!.ItemSpec)!;
+			Assert.AreEqual (expectedMinimumOSVersion, plist.GetMinimumOSVersion (), "MinimumOSVersion");
+		}
+
 		[Test]
 		public void ErrorWithMismatchedInfoPlistMinimumOSVersion ()
 		{