Merge branch 'master' into mono-2018-06

docs/website/mmp-errors.md

@@ -156,6 +156,8 @@ Alternatively, enable the managed [linker](https://docs.microsoft.com/xamarin/ma
 
 As a last-straw solution, use an older version of Xamarin.Mac that does not require these new SDKs to be present during the build process.
 
+<!-- 0136 and 0137 used by mtouch -->
+
 # MM1xxx: file copy / symlinks (project related)
 
 ### <a name="MM1034">MM1034: Could not create symlink '{file}' -> '{target}': error {number}

docs/website/mtouch-errors.md

@@ -683,6 +683,22 @@ Alternatively, enable the managed [linker](https://docs.microsoft.com/en-us/xama
 
 As a last-straw solution, use an older version of Xamarin.iOS that does not require these new SDKs to be present during the build process.
 
+### <a name="MT0136"/>MT0136: Cannot find the assembly {assembly} referenced from {assembly}.
+
+This warning occurs when an assembly passed to mtouch contains a reference to
+another assembly that can't be found.
+
+mtouch may in certain cases still find references at a later point, which
+means that if the build otherwise succeeds, this warning can be ignored.
+
+### <a name="MT0137"/>MT0137: Cannot find the assembly {assembly}, referenced by an attribute in {assembly}.
+
+This warning occurs when an attribute contains a reference to another assembly
+that can't be found.
+
+mtouch may in certain cases still find references at a later point, which
+means that if the build otherwise succeeds, this warning can be ignored.
+
 # MT1xxx: Project related error messages
 
 ### MT10xx: Installer / mtouch

external/mono

@@ -1 +1 @@
-Subproject commit 0e0e4a68f947748fdcde3d83d28c99b613f23ba3
+Subproject commit dc815ae5623e963e6fce54dec8a2601bcf501084

msbuild/Xamarin.MacDev.Tasks.Core/Tasks/PropertyListEditorTaskBase.cs

@@ -29,7 +29,7 @@ namespace Xamarin.MacDev.Tasks
 
 		public string Type { get; set; }
 
-		public string Value;
+		public string Value { get; set; }
 
 		static string GetType (PObject value)
 		{

src/Foundation/NSErrorException.cs

@@ -55,5 +55,11 @@ namespace Foundation {
 		{
 			get {return error.UserInfo; }
 		}
+
+		public override string Message {
+			get {
+				return error.Description;
+			}
+		}
 	}
 }

tests/common/BundlerTool.cs

@@ -44,6 +44,7 @@ namespace Xamarin.Tests
 	abstract class BundlerTool : Tool
 	{
 		public const string None = "None";
+		public bool AlwaysShowOutput;
 
 #pragma warning disable 0649 // Field 'X' is never assigned to, and will always have its default value Y
 		// These map directly to mtouch/mmp options
@@ -306,7 +307,7 @@ namespace Xamarin.Tests
 
 		public virtual int Execute ()
 		{
-			return Execute (ToolArguments, always_show_output: Verbosity > 0);
+			return Execute (ToolArguments, always_show_output: Verbosity > 0 || AlwaysShowOutput);
 		}
 
 		public virtual void AssertExecute (string message = null)

tests/monotouch-test/ObjCRuntime/RegistrarTest.cs

@@ -2690,4 +2690,43 @@ namespace MonoTouchFixtures.ObjCRuntime {
 	public class SomeConsumer : NSObject, ISomeDelegate
 	{
 	}
+#if !__WATCHOS__ // no MetalKit on watchOS
+	// These classes implement Metal* protocols, so that the generated registrar code includes the corresponding Metal* headers.
+	// https://github.com/xamarin/xamarin-macios/issues/4422
+	class MetalKitTypesInTheSimulator : NSObject, MetalKit.IMTKViewDelegate {
+		public void Draw (MetalKit.MTKView view)
+		{
+			throw new NotImplementedException ();
+		}
+
+		public void DrawableSizeWillChange (MetalKit.MTKView view, CGSize size)
+		{
+			throw new NotImplementedException ();
+		}
+	}
+	class MetalTypesInTheSimulator : NSObject, global::Metal.IMTLDrawable {
+		public void Present ()
+		{
+			throw new NotImplementedException ();
+		}
+
+		public void Present (double presentationTime)
+		{
+			throw new NotImplementedException ();
+		}
+	}
+#if !__TVOS__ // MetalPerformanceShaders isn't available in the tvOS simulator either
+	class MetalPerformanceShadersTypesInTheSimulator : NSObject, global::MetalPerformanceShaders.IMPSDeviceProvider {
+		public global::Metal.IMTLDevice GetMTLDevice ()
+		{
+			throw new NotImplementedException ();
+		}
+
+		public void Present (double presentationTime)
+		{
+			throw new NotImplementedException ();
+		}
+	}
+#endif // !__TVOS__
+#endif // !__WATCHOS__
 }

tests/monotouch-test/SafariServices/ReadingListTest.cs

@@ -59,6 +59,18 @@ namespace MonoTouchFixtures.SafariServices {
 				Assert.False (rl.Add (local, null, null, out error), "Add-3");
 				Assert.That (error.Domain, Is.EqualTo ((string) SSReadingList.ErrorDomain), "Domain");
 				Assert.That (error.Code, Is.EqualTo ((nint) (int) SSReadingListError.UrlSchemeNotAllowed), "Code");
+
+				try {
+					throw new NSErrorException (error);
+				}
+				catch (NSErrorException ns) {
+					Assert.That (ns.Error.Code, Is.EqualTo (error.Code), "Code");
+					Assert.That (ns.Error.Domain, Is.EqualTo (error.Domain), "Domain");
+					Assert.That (ns.Message, Is.EqualTo (error.Description), "Message");
+				}
+				catch (Exception e) {
+					Assert.Fail (e.ToString ());
+				}
 			}
 		}
 

tests/mtouch/MTouch.cs

@@ -1716,6 +1716,67 @@ public class TestApp {
 			}
 		}
 
+		[Test]
+		public void MT0136 ()
+		{
+			using (var mtouch = new MTouchTool ()) {
+				var tmpdir = mtouch.CreateTemporaryDirectory ();
+				mtouch.CreateTemporaryCacheDirectory ();
+
+				var codeDll = @"public class A {}";
+				var codeExe = @"public class B : A {}";
+
+				var dllPath = CompileTestAppLibrary (tmpdir, codeDll, profile: Profile.iOS, appName: "A");
+
+				mtouch.CreateTemporaryApp (extraCode: codeExe, extraArg: $"-r:{StringUtils.Quote (dllPath)}");
+				mtouch.Debug = false;
+				mtouch.Linker = MTouchLinker.DontLink;
+				File.Delete (dllPath);
+				mtouch.AssertExecuteFailure (MTouchAction.BuildSim, "build");
+				mtouch.AssertWarningPattern (136, "Cannot find the assembly 'A, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' referenced from '.*/testApp.exe'.");
+				mtouch.AssertError (2002, "Failed to resolve assembly: 'A, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'");
+				mtouch.AssertErrorCount (1);
+				mtouch.AssertWarningCount (1);
+			}
+		}
+
+		[Test]
+		public void MT0137 ()
+		{
+			using (var mtouch = new MTouchTool ()) {
+				var tmpdir = mtouch.CreateTemporaryDirectory ();
+				mtouch.CreateTemporaryCacheDirectory ();
+
+				var codeDll = @"public class A {}";
+				var codeExe = @"
+[assembly: MyCustomAttribute (typeof (A))]
+
+public class MyCustomAttribute : System.Attribute
+{
+	public MyCustomAttribute (System.Type type) {}
+}
+
+[System.Diagnostics.DebuggerTypeProxyAttribute (typeof (A))]
+public class B
+{
+}
+";
+				var codeExeFile = Path.Combine (tmpdir, "extraCode.cs");
+				File.WriteAllText (codeExeFile, codeExe);
+				var dllPath = CompileTestAppLibrary (tmpdir, codeDll, profile: Profile.iOS, appName: "A");
+
+				mtouch.CreateTemporaryApp (extraArg: $"-r:{StringUtils.Quote (dllPath)} {StringUtils.Quote (codeExeFile)}");
+				mtouch.Debug = false;
+				mtouch.Linker = MTouchLinker.DontLink;
+				File.Delete (dllPath);
+				mtouch.AlwaysShowOutput = true;
+				mtouch.AssertExecute (MTouchAction.BuildSim, "build");
+				mtouch.AssertWarning (137, "Cannot find the assembly 'A, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null', referenced by a MyCustomAttribute attribute in 'testApp.exe'.");
+				mtouch.AssertWarning (137, "Cannot find the assembly 'A, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null', referenced by a System.Diagnostics.DebuggerTypeProxyAttribute attribute in 'testApp.exe'.");
+				mtouch.AssertWarningCount (2);
+			}
+		}
+
 		[Test]
 		[TestCase ("all")]
 		[TestCase ("-all")]

tests/mtouch/RegistrarTest.cs

@@ -278,7 +278,7 @@ class MyObjectErr : NSObject, IFoo1, IFoo2
 				mtouch.CreateTemporaryApp (extraCode: sb.ToString (), usings: "using System; using Foundation; using ObjCRuntime;", extraArg: "/debug:full");
 				mtouch.Linker = MTouchLinker.LinkSdk;
 				mtouch.Registrar = MTouchRegistrar.Static;
-				mtouch.AssertExecuteFailure ();
+				mtouch.AssertExecuteFailure (MTouchAction.BuildDev);
 				var invalidFrameworks = new [] {
 					new { Framework = "IdentityLookup", Version = "11.0" },
 					new { Framework = "FileProviderUI", Version = "11.0" },
@@ -296,6 +296,8 @@ class MyObjectErr : NSObject, IFoo1, IFoo2
 					mtouch.AssertError (4134, $"Your application is using the '{framework.Framework}' framework, which isn't included in the iOS SDK you're using to build your app (this framework was introduced in iOS {framework.Version}, while you're building with the iOS {mtouch.Sdk} SDK.) Please select a newer SDK in your app's iOS Build options.");
 				mtouch.AssertErrorCount (invalidFrameworks.Length);
 				mtouch.AssertWarningCount (0);
+
+				mtouch.AssertExecute (MTouchAction.BuildSim);
 			}
 		}
 

tools/common/Assembly.cs

@@ -368,6 +368,13 @@ namespace Xamarin.Bundler {
 					
 					string file = Path.GetFileNameWithoutExtension (name);
 
+#if !MONOMAC
+					if (App.IsSimulatorBuild && !Driver.IsFrameworkAvailableInSimulator (App, file)) {
+						Driver.Log (3, "Not linking with {0} (referenced by a module reference in {1}) because it's not available in the simulator.", file, FileName);
+						continue;
+					}
+#endif
+
 					switch (file) {
 					// special case
 					case "__Internal":
@@ -402,21 +409,6 @@ namespace Xamarin.Bundler {
 						if (Frameworks.Add ("Accelerate"))
 							Driver.Log (3, "Linking with the framework Accelerate because {0} is referenced by a module reference in {1}", file, FileName);
 						break;
-					case "CoreAudioKit":
-					case "Metal":
-					case "MetalKit":
-					case "MetalPerformanceShaders":
-					case "CoreNFC":
-					case "DeviceCheck":
-						// some frameworks do not exists on simulators and will result in linker errors if we include them
-#if MTOUCH
-						if (!App.IsSimulatorBuild) {
-#endif
-							AddFramework (file);
-#if MTOUCH
-						}
-#endif
-						break;
 					case "openal32":
 						if (Frameworks.Add ("OpenAL"))
 							Driver.Log (3, "Linking with the framework OpenAL because {0} is referenced by a module reference in {1}", file, FileName);

tools/common/Frameworks.cs

@@ -13,6 +13,7 @@ public class Framework
 	public string Namespace;
 	public string Name;
 	public Version Version;
+	public Version VersionAvailableInSimulator;
 }
 
 public class Frameworks : Dictionary <string, Framework>
@@ -42,7 +43,7 @@ public class Frameworks : Dictionary <string, Framework>
 		Add (@namespace, framework, new Version (major_version, minor_version, build_version));
 	}
 
-	public void Add (string @namespace, string framework, Version version)
+	public void Add (string @namespace, string framework, Version version, Version version_available_in_simulator = null)
 	{
 		var fr = new Framework () {
 #if MTOUCH || MMP
@@ -51,7 +52,8 @@ public class Frameworks : Dictionary <string, Framework>
 			Namespace = @namespace,
 #endif
 			Name = framework,
-			Version = version
+			Version = version,
+			VersionAvailableInSimulator = version_available_in_simulator ?? version,
 		};
 		base.Add (fr.Namespace, fr);
 	}
@@ -64,6 +66,8 @@ public class Frameworks : Dictionary <string, Framework>
 		return null;
 	}
 
+	static Version NotAvailableInSimulator = new Version (int.MaxValue, int.MaxValue);
+
 	static Frameworks mac_frameworks;
 	public static Frameworks MacFrameworks {
 		get {
@@ -239,7 +243,7 @@ public class Frameworks : Dictionary <string, Framework>
 				{ "CloudKit", "CloudKit", 8 },
 				{ "AVKit", "AVKit", 8 },
 				{ "CoreAudioKit", "CoreAudioKit", app.IsSimulatorBuild ? 9 : 8 },
-				{ "Metal", "Metal", 8 },
+				{ "Metal", "Metal", new Version (8, 0), new Version (9, 0) },
 				{ "WebKit", "WebKit", 8 },
 				{ "NetworkExtension", "NetworkExtension", 8 },
 				{ "VideoToolbox", "VideoToolbox", 8 },
@@ -252,7 +256,7 @@ public class Frameworks : Dictionary <string, Framework>
 				{ "WatchConnectivity", "WatchConnectivity", 9 },
 				{ "ModelIO", "ModelIO", 9 },
 				{ "MetalKit", "MetalKit", 9 },
-				{ "MetalPerformanceShaders", "MetalPerformanceShaders", 9 },
+				{ "MetalPerformanceShaders", "MetalPerformanceShaders", new Version (9, 0), new Version (11, 0) /* MPS got simulator headers in Xcode 9 */ },
 				{ "GameplayKit", "GameplayKit", 9 },
 				{ "HealthKitUI", "HealthKitUI", 9,3 },
 
@@ -267,9 +271,9 @@ public class Frameworks : Dictionary <string, Framework>
 
 				{ "ARKit", "ARKit", 11 },
 				{ "CoreNFC", "CoreNFC", 11 },
-				{ "DeviceCheck", "DeviceCheck", 11 },
+				{ "DeviceCheck", "DeviceCheck", new Version (11, 0), NotAvailableInSimulator /* no headers provided for simulator */ },
 				{ "IdentityLookup", "IdentityLookup", 11 },
-				{ "IOSurface", "IOSurface", 11 },
+				{ "IOSurface", "IOSurface", new Version (11, 0), NotAvailableInSimulator /* Not available in the simulator (the header is there, but broken) */  },
 				{ "CoreML", "CoreML", 11 },
 				{ "Vision", "Vision", 11 },
 				{ "FileProvider", "FileProvider", 11 },
@@ -317,7 +321,7 @@ public class Frameworks : Dictionary <string, Framework>
 				// AVFoundation was introduced in 3.0, but the simulator SDK was broken until 3.2.
 				{ "AVFoundation", "AVFoundation", 3, app.IsSimulatorBuild ? 2 : 0 },
 				{ "CloudKit", "CloudKit", 3 },
-				{ "GameKit", "GameKit", 3 },
+				{ "GameKit", "GameKit", new Version (3, 0), new Version (3, 2) /* No headers provided for watchOS/simulator until watchOS 3.2. */ },
 				{ "SceneKit", "SceneKit", 3 },
 				{ "SpriteKit", "SpriteKit", 3 },
 				{ "UserNotifications", "UserNotifications", 3 },
@@ -366,7 +370,7 @@ public class Frameworks : Dictionary <string, Framework>
 					{ "MediaToolbox", "MediaToolbox", 9 },
 					{ "Metal", "Metal", 9 },
 					{ "MetalKit", "MetalKit", 9 },
-					{ "MetalPerformanceShaders", "MetalPerformanceShaders", 9 },
+					{ "MetalPerformanceShaders", "MetalPerformanceShaders", new Version (9, 0), NotAvailableInSimulator /* not available in the simulator */ },
 					{ "CoreServices", "CFNetwork", 9 },
 					{ "MobileCoreServices", "MobileCoreServices", 9 },
 					{ "ModelIO", "ModelIO", 9 },
@@ -392,9 +396,9 @@ public class Frameworks : Dictionary <string, Framework>
 					{ "VideoSubscriberAccount", "VideoSubscriberAccount", 10 },
 					{ "VideoToolbox", "VideoToolbox", 10,2 },
 
-					{ "DeviceCheck", "DeviceCheck", 11 },
+					{ "DeviceCheck", "DeviceCheck", new Version (11, 0), NotAvailableInSimulator /* no headers provided for simulator */ },
 					{ "CoreML", "CoreML", 11 },
-					{ "IOSurface", "IOSurface", 11 },
+					{ "IOSurface", "IOSurface", new Version (11, 0), NotAvailableInSimulator /* Not available in the simulator (the header is there, but broken) */  },
 					{ "Vision", "Vision", 11 },
 				};
 			}

tools/common/StaticRegistrar.cs

@@ -2053,6 +2053,13 @@ namespace Registrar {
 			
 			namespaces.Add (ns);
 
+#if !MMP
+			if (App.IsSimulatorBuild && !Driver.IsFrameworkAvailableInSimulator (App, ns)) {
+				Driver.Log (5, "Not importing the framework {0} in the generated registrar code because it's not available in the simulator.", ns);
+				return;
+			}
+#endif
+
 			string h;
 			switch (ns) {
 #if MMP
@@ -2121,30 +2128,6 @@ namespace Registrar {
 				}
 				goto default;
 #endif
-			case "CoreAudioKit":
-				// fatal error: 'CoreAudioKit/CoreAudioKit.h' file not found
-				// radar filed with Apple - but that framework / header is not yet shipped with the iOS SDK simulator
-#if MTOUCH
-				if (IsSimulator)
-					return;
-#endif
-				goto default;
-			case "Metal":
-			case "MetalKit":
-			case "MetalPerformanceShaders": // https://trello.com/c/mrjkAO9U/518-metal-simulator
-				// #error Metal Simulator is currently unsupported
-				// this framework is _officially_ not available on the simulator (in iOS8)
-#if !MONOMAC
-				if (IsSimulator)
-					return;
-#endif
-				goto default;
-			case "GameKit":
-#if !MONOMAC
-				if (IsSimulator && App.Platform == Xamarin.Utils.ApplePlatform.WatchOS && App.SdkVersion < new Version (3, 2))
-					return; // No headers provided for watchOS/simulator until watchOS 3.2.
-#endif
-				goto default;
 			case "WatchKit":
 				// There's a bug in Xcode 7 beta 2 headers where the build fails with
 				// ObjC++ files if WatchKit.h is included before UIKit.h (radar 21651022).
@@ -2154,12 +2137,6 @@ namespace Registrar {
 				header.WriteLine ("#import <WatchKit/WatchKit.h>");
 				namespaces.Add ("UIKit");
 				return;
-			case "DeviceCheck":
-#if !MONOMAC
-				if (IsSimulator)
-					return; // No headers provided for simulator
-#endif
-				goto default;
 			case "QTKit":
 #if MONOMAC
 				if (App.SdkVersion >= MacOSTenTwelveVersion)
@@ -2167,10 +2144,6 @@ namespace Registrar {
 #endif
 				goto default;
 			case "IOSurface": // There is no IOSurface.h
-#if !MONOMAC
-				if (IsSimulator)
-					return; // Not available in the simulator (the header is there, but broken).
-#endif
 				h = "<IOSurface/IOSurfaceObjC.h>";
 				break;
 			default:
@@ -2586,21 +2559,16 @@ namespace Registrar {
 		static bool IsIntentsType (ObjCType type) => IsTypeCore (type, "Intents");
 		static bool IsExternalAccessoryType (ObjCType type) => IsTypeCore (type, "ExternalAccessory");
 
-		static bool IsMetalType (ObjCType type)
+#if !MONOMAC
+		bool IsTypeAllowedInSimulator (ObjCType type)
 		{
 			var ns = type.Type.Namespace;
 			if (!IsDualBuild)
 				ns = ns.Substring (CompatNamespace.Length + 1);
 
-			switch (ns) {
-			case "Metal":
-			case "MetalKit":
-			case "MetalPerformanceShaders":
-				return true;
-			default:
-				return false;
-			}
+			return Driver.IsFrameworkAvailableInSimulator (App, ns);
 		}
+#endif
 
 		class ProtocolInfo
 		{
@@ -2676,8 +2644,10 @@ namespace Registrar {
 
 #if !MONOMAC
 				var isPlatformType = IsPlatformType (@class.Type);
-				if (isPlatformType && IsSimulatorOrDesktop && IsMetalType (@class))
-					continue; // Metal isn't supported in the simulator.
+				if (isPlatformType && IsSimulatorOrDesktop && !IsTypeAllowedInSimulator (@class)) {
+					Driver.Log (5, "The static registrar won't generate code for {0} because its framework is not supported in the simulator.", @class.ExportedName);
+					continue; // Some types are not supported in the simulator.
+				}
 #else
 				// Don't register 64-bit only API on 32-bit XM
 				if (!Is64Bits && IsOnly64Bits (@class.Type))

tools/linker/MobileSweepStep.cs

@@ -32,13 +32,13 @@ namespace Xamarin.Linker {
 				switch (CurrentAction) {
 				case AssemblyAction.Link:
 				case AssemblyAction.Save:
-					SweepAssembly (assembly);
+					SweepAssemblyDefinition (assembly);
 					break;
 				}
 			}
 		}
 
-		protected virtual void SweepAssembly (AssemblyDefinition assembly)
+		protected virtual void SweepAssemblyDefinition (AssemblyDefinition assembly)
 		{
 			SweepMainModule (assembly.MainModule);
 		}

tools/linker/MonoTouch.Tuner/MonoTouchSweepStep.cs

@@ -15,9 +15,9 @@ namespace MonoTouch.Tuner {
 		{
 		}
 
-		protected override void SweepAssembly (AssemblyDefinition assembly)
+		protected override void SweepAssemblyDefinition (AssemblyDefinition assembly)
 		{
-			base.SweepAssembly (assembly);
+			base.SweepAssemblyDefinition (assembly);
 
 			if (assembly.HasCustomAttributes)
 				SweepAttributes (assembly.CustomAttributes);

tools/mmp/mmp.csproj

@@ -7,7 +7,7 @@
     <OutputType>Exe</OutputType>
     <RootNamespace>linker</RootNamespace>
     <AssemblyName>mmp</AssemblyName>
-    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.6</TargetFrameworkVersion>
     <UseXamMacFullFramework>true</UseXamMacFullFramework>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">

tools/mtouch/Makefile

@@ -273,6 +273,9 @@ SIMLAUNCHER_FRAMEWORKS =  \
 	-weak_framework WatchConnectivity			\
 	-weak_framework ModelIO						\
 	-weak_framework GameplayKit					\
+	-weak_framework Metal						\
+	-weak_framework MetalKit					\
+	-weak_framework MetalPerformanceShaders		\
 						\
 	-weak_framework HealthKitUI					\
 						\
@@ -297,6 +300,7 @@ SIMLAUNCHER_FRAMEWORKS =  \
 # note 2: there's no GameKit, in iOS 9 (beta 3 at least), you're supposed to reference GameCenter instead (looks fixed in beta 4)
 # note 3: there's no MetalKit or MetalPerformanceShaders in iOS 9 beta 4 - but other frameworks were added
 # note 4: GameCenter was removed in Xcode 7 beta 5, and GameKit is back.
+# note 5: Metal* seems to be supported as of some Xcode 7 beta (b2 didn't, but the final release does)
 
 # keep the above list of weak_framework in sync with mtouch.cs
 # except it is no a mistake that GameController and MediaAccessibility (#13636) are not built into simlauncher

tools/mtouch/Target.cs

@@ -393,6 +393,10 @@ namespace Xamarin.Bundler
 				}
 
 				var reference_assembly = ManifestResolver.Resolve (reference);
+				if (reference_assembly == null) {
+					ErrorHelper.Warning (136, "Cannot find the assembly '{0}' referenced from '{1}'.", reference.FullName, main.FileName);
+					continue;
+				}
 				ComputeListOfAssemblies (assemblies, reference_assembly, exceptions);
 			}
 
@@ -402,39 +406,36 @@ namespace Xamarin.Bundler
 			// Custom Attribute metadata can include references to other assemblies, e.g. [X (typeof (Y)], 
 			// but it is not reflected in AssemblyReferences :-( ref: #37611
 			// so we must scan every custom attribute to look for System.Type
-			GetCustomAttributeReferences (assembly, assemblies, exceptions);
-			GetCustomAttributeReferences (main, assemblies, exceptions);
-			if (main.HasTypes) {
-				foreach (var ca in main.GetCustomAttributes ())
-					GetCustomAttributeReferences (ca, assemblies, exceptions);
-			}
+			GetCustomAttributeReferences (main, main, assemblies, exceptions);
+			foreach (var ca in main.GetCustomAttributes ())
+				GetCustomAttributeReferences (main, ca, assemblies, exceptions);
 		}
 
-		void GetCustomAttributeReferences (ICustomAttributeProvider cap, HashSet<string> assemblies, List<Exception> exceptions)
+		void GetCustomAttributeReferences (ModuleDefinition main, ICustomAttributeProvider cap, HashSet<string> assemblies, List<Exception> exceptions)
 		{
 			if (!cap.HasCustomAttributes)
 				return;
 			foreach (var ca in cap.CustomAttributes)
-				GetCustomAttributeReferences (ca, assemblies, exceptions);
+				GetCustomAttributeReferences (main, ca, assemblies, exceptions);
 		}
 
-		void GetCustomAttributeReferences (CustomAttribute ca, HashSet<string> assemblies, List<Exception> exceptions)
+		void GetCustomAttributeReferences (ModuleDefinition main, CustomAttribute ca, HashSet<string> assemblies, List<Exception> exceptions)
 		{
 			if (ca.HasConstructorArguments) {
 				foreach (var arg in ca.ConstructorArguments)
-					GetCustomAttributeArgumentReference (arg, assemblies, exceptions);
+					GetCustomAttributeArgumentReference (main, ca, arg, assemblies, exceptions);
 			}
 			if (ca.HasFields) {
 				foreach (var arg in ca.Fields)
-					GetCustomAttributeArgumentReference (arg.Argument, assemblies, exceptions);
+					GetCustomAttributeArgumentReference (main, ca, arg.Argument, assemblies, exceptions);
 			}
 			if (ca.HasProperties) {
 				foreach (var arg in ca.Properties)
-					GetCustomAttributeArgumentReference (arg.Argument, assemblies, exceptions);
+					GetCustomAttributeArgumentReference (main, ca, arg.Argument, assemblies, exceptions);
 			}
 		}
 
-		void GetCustomAttributeArgumentReference (CustomAttributeArgument arg, HashSet<string> assemblies, List<Exception> exceptions)
+		void GetCustomAttributeArgumentReference (ModuleDefinition main, CustomAttribute ca, CustomAttributeArgument arg, HashSet<string> assemblies, List<Exception> exceptions)
 		{
 			if (!arg.Type.Is ("System", "Type"))
 				return;
@@ -442,6 +443,10 @@ namespace Xamarin.Bundler
 			if (ar == null)
 				return;
 			var reference_assembly = ManifestResolver.Resolve (ar);
+			if (reference_assembly == null) {
+				ErrorHelper.Warning (137, "Cannot find the assembly '{0}', referenced by a {2} attribute in '{1}'.", ar.FullName, main.Name, ca.AttributeType.FullName);
+				return;
+			}
 			ComputeListOfAssemblies (assemblies, reference_assembly, exceptions);
 		}
 

tools/mtouch/mtouch.cs

@@ -1677,5 +1677,19 @@ namespace Xamarin.Bundler
 				throw ErrorHelper.CreateError (71, "Unknown platform: {0}. This usually indicates a bug in Xamarin.iOS; please file a bug report at http://bugzilla.xamarin.com with a test case.", app.Platform);
 			}
 		}
+
+		public static bool IsFrameworkAvailableInSimulator (Application app, string framework)
+		{
+			if (!GetFrameworks (app).TryGetValue (framework, out var fw))
+				return true; // Unknown framework, assume it's valid for the simulator
+
+			if (fw.VersionAvailableInSimulator == null)
+				return false;
+
+			if (fw.VersionAvailableInSimulator > app.SdkVersion)
+				return false;
+
+			return true;
+		}
 	}
 }

tools/mtouch/mtouch.csproj

@@ -372,6 +372,12 @@
     <Compile Include="..\..\src\ObjCRuntime\BindingImplAttribute.cs">
       <Link>external\maccore\BindingImplAttribute.cs</Link>
     </Compile>
+    <Compile Include="..\..\external\mono\external\linker\linker\Linker\AssemblyUtilities.cs">
+      <Link>Linker\AssemblyUtilities.cs</Link>
+    </Compile>
+    <Compile Include="..\..\external\mono\external\linker\linker\Linker\TypeNameParser.cs">
+      <Link>Linker\TypeNameParser.cs</Link>
+    </Compile>
   </ItemGroup>
   <ItemGroup>
     <Reference Include="System.Core" />