[mtouch] Bundle duplicated assemblies in the container app. Fixes #58873. (#3626)

Assemblies that satisfy all of these conditions:

* Are not in the container project.
* Are in multiple app extensions.

can (and should) be bundled in the container app.

Fixes https://bugzilla.xamarin.com/show_bug.cgi?id=58873

tests/mtouch/MTouch.cs

@@ -3033,6 +3033,43 @@ class Test {
 			}
 		}
 
+		[Test]
+		public void ExtensionsWithSharedLibrary ()
+		{
+			using (var tool = new MTouchTool ()) {
+				tool.CreateTemporaryApp ();
+				tool.CreateTemporaryCacheDirectory ();
+				tool.Linker = MTouchLinker.LinkSdk;
+
+				var tmpdir = tool.CreateTemporaryDirectory ();
+				var dll = CompileTestAppLibrary (tmpdir, "public class L {}", appName: "commonTestLibrary");
+
+				using (var ext1 = new MTouchTool ()) {
+					ext1.References = new string [] { dll };
+					ext1.CreateTemporaryCacheDirectory ();
+					ext1.CreateTemporaryTodayExtension (extraCode: "class E1 : L {}", extraArg: $"-r:{StringUtils.Quote (dll)}");
+					ext1.Linker = MTouchLinker.LinkSdk;
+					tool.AppExtensions.Add (ext1);
+
+					using (var ext2 = new MTouchTool ()) {
+						ext2.References = new string [] { dll };
+						ext2.CreateTemporaryCacheDirectory ();
+						ext2.CreateTemporaryServiceExtension (extraCode: "class E1 : L {}", extraArg: $"-r:{StringUtils.Quote (dll)}");
+						ext2.Linker = MTouchLinker.LinkSdk;
+						tool.AppExtensions.Add (ext2);
+
+						ext2.AssertExecute (MTouchAction.BuildDev, "ext 2 build");
+						ext1.AssertExecute (MTouchAction.BuildDev, "ext 1 build");
+						tool.AssertExecute (MTouchAction.BuildDev, "main build");
+
+						Assert.That (Path.Combine (ext1.AppPath, Path.GetFileName (dll)), Does.Not.Exist, "ext1 existence");
+						Assert.That (Path.Combine (ext2.AppPath, Path.GetFileName (dll)), Does.Not.Exist, "ext2 existence");
+						Assert.That (Path.Combine (tool.AppPath, Path.GetFileName (dll)), Does.Exist, "existence");
+					}
+				}
+			}
+		}
+
 		[Test]
 		public void LinkWithNoLibrary ()
 		{

tools/mtouch/Application.cs

@@ -2109,7 +2109,7 @@ namespace Xamarin.Bundler {
 				var size_specific = assemblies.Length > 1 && !Cache.CompareAssemblies (assemblies [0].FullPath, assemblies [1].FullPath, true, true);
 
 				if (IsExtension && !IsWatchExtension) {
-					var codeShared = assemblies.Count ((v) => v.IsCodeShared);
+					var codeShared = assemblies.Count ((v) => v.IsCodeShared || v.BundleInContainerApp);
 					if (codeShared > 0) {
 						if (codeShared != assemblies.Length)
 							throw ErrorHelper.CreateError (99, $"Internal error: all assemblies in a joined build target must have the same code sharing options ({string.Join (", ", assemblies.Select ((v) => v.Identity + "=" + v.IsCodeShared))}). Please file a bug report with a test case (http://bugzilla.xamarin.com).");

tools/mtouch/Assembly.cs

@@ -33,6 +33,7 @@ namespace Xamarin.Bundler {
 		public AssemblyBuildTarget BuildTarget;
 		public string BuildTargetName;
 		public bool IsCodeShared;
+		public bool BundleInContainerApp;
 
 		public Dictionary<Abi, AotInfo> AotInfos = new Dictionary<Abi, AotInfo> ();
 

tools/mtouch/Target.cs

@@ -696,6 +696,20 @@ namespace Xamarin.Bundler
 						t.Resolver.Add (asm.AssemblyDefinition);
 				}
 
+				// Find assemblies that are in more than 1 appex, but not in the container app.
+				// These assemblies will be bundled once into the container .app instead of in each appex.
+				var grouped = sharingTargets.SelectMany ((v) => v.Assemblies).
+							    GroupBy ((v) => Assembly.GetIdentity (v.AssemblyDefinition)).
+							    Where ((v) => !Assemblies.ContainsKey (v.Key)).
+							    Where ((v) => v.Count () > 1);
+				foreach (var gr in grouped) {
+					var asm = gr.First ();
+					Assemblies.Add (asm);
+					Resolver.Add (asm.AssemblyDefinition);
+					gr.All ((v) => v.BundleInContainerApp = true);
+				}
+				                                                                       
+
 				// If any of the appex'es build to a grouped SDK framework, then we must ensure that all SDK assemblies
 				// in that appex are also in the container app.
 				foreach (var st in sharingTargets) {