Update code to implemented some requested changes

Author: grendello

src/Xamarin.Android.Build.Tasks/Tasks/GenerateJavaStubs.cs

@@ -183,9 +183,7 @@ void Run (DirectoryAssemblyResolver res)
 				if (!userAssemblies.ContainsKey (name))
 					userAssemblies.Add (name, asm.ItemSpec);
 #if ENABLE_MARSHAL_METHODS
-				if (!Debug) {
-					StoreMarshalAssemblyPath (name, asm);
-				}
+				StoreMarshalAssemblyPath (name, asm);
 #endif
 			}
 

src/Xamarin.Android.Build.Tasks/Tasks/GeneratePackageManagerJava.cs

@@ -444,7 +444,7 @@ void AddEnvironment ()
 #if ENABLE_MARSHAL_METHODS
 			var marshalMethodsState = BuildEngine4.GetRegisteredTaskObjectAssemblyLocal<MarshalMethodsState> (GenerateJavaStubs.MarshalMethodsRegisterTaskKey, RegisteredTaskObjectLifetime.Build);
 
-			var marshalMethodsAsmGen = new MarshalMethodsNativeAssemblyGenerator () {
+			var marshalMethodsAsmGen = new MarshalMethodsNativeAssemblyGenerator {
 				NumberOfAssembliesInApk = assemblyCount,
 				UniqueAssemblyNames = uniqueAssemblyNames,
 				MarshalMethods = marshalMethodsState?.MarshalMethods,

src/Xamarin.Android.Build.Tasks/Utilities/MarshalMethodsAssemblyRewriter.cs

@@ -10,11 +10,11 @@ namespace Xamarin.Android.Tasks
 {
 	class MarshalMethodsAssemblyRewriter
 	{
-		IDictionary<string, MarshalMethodEntry> methods;
+		IDictionary<string, IList<MarshalMethodEntry>> methods;
 		ICollection<AssemblyDefinition> uniqueAssemblies;
 		IDictionary <string, HashSet<string>> assemblyPaths;
 
-		public MarshalMethodsAssemblyRewriter (IDictionary<string, MarshalMethodEntry> methods, ICollection<AssemblyDefinition> uniqueAssemblies, IDictionary <string, HashSet<string>> assemblyPaths)
+		public MarshalMethodsAssemblyRewriter (IDictionary<string, IList<MarshalMethodEntry>> methods, ICollection<AssemblyDefinition> uniqueAssemblies, IDictionary <string, HashSet<string>> assemblyPaths)
 		{
 			this.methods = methods ?? throw new ArgumentNullException (nameof (methods));
 			this.uniqueAssemblies = uniqueAssemblies ?? throw new ArgumentNullException (nameof (uniqueAssemblies));
@@ -23,17 +23,20 @@ public MarshalMethodsAssemblyRewriter (IDictionary<string, MarshalMethodEntry> m
 
 		public void Rewrite (DirectoryAssemblyResolver resolver)
 		{
+			MethodDefinition unmanagedCallersOnlyAttributeCtor = GetUnmanagedCallersOnlyAttributeConstructor (resolver);
 			var unmanagedCallersOnlyAttributes = new Dictionary<AssemblyDefinition, CustomAttribute> ();
 			foreach (AssemblyDefinition asm in uniqueAssemblies) {
-				unmanagedCallersOnlyAttributes.Add (asm, GetUnmanagedCallersOnlyAttribute (asm, resolver));
+				unmanagedCallersOnlyAttributes.Add (asm, CreateImportedUnmanagedCallersOnlyAttribute (asm, unmanagedCallersOnlyAttributeCtor));
 			}
 
 			Console.WriteLine ("Adding the [UnmanagedCallersOnly] attribute to native callback methods and removing unneeded fields+methods");
-			foreach (MarshalMethodEntry method in methods.Values) {
-				Console.WriteLine ($"\t{method.NativeCallback.FullName} (token: 0x{method.NativeCallback.MetadataToken.RID:x})");
-				method.NativeCallback.CustomAttributes.Add (unmanagedCallersOnlyAttributes [method.NativeCallback.Module.Assembly]);
-				method.Connector.DeclaringType.Methods.Remove (method.Connector);
-				method.CallbackField?.DeclaringType.Fields.Remove (method.CallbackField);
+			foreach (IList<MarshalMethodEntry> methodList in methods.Values) {
+				foreach (MarshalMethodEntry method in methodList) {
+					Console.WriteLine ($"\t{method.NativeCallback.FullName} (token: 0x{method.NativeCallback.MetadataToken.RID:x})");
+					method.NativeCallback.CustomAttributes.Add (unmanagedCallersOnlyAttributes [method.NativeCallback.Module.Assembly]);
+					method.Connector.DeclaringType.Methods.Remove (method.Connector);
+					method.CallbackField?.DeclaringType.Fields.Remove (method.CallbackField);
+				}
 			}
 
 			Console.WriteLine ();
@@ -75,8 +78,10 @@ public void Rewrite (DirectoryAssemblyResolver resolver)
 
 			Console.WriteLine ();
 			Console.WriteLine ("Method tokens:");
-			foreach (MarshalMethodEntry method in methods.Values) {
-				Console.WriteLine ($"\t{method.NativeCallback.FullName} (token: 0x{method.NativeCallback.MetadataToken.RID:x})");
+			foreach (IList<MarshalMethodEntry> methodList in methods.Values) {
+				foreach (MarshalMethodEntry method in methodList) {
+					Console.WriteLine ($"\t{method.NativeCallback.FullName} (token: 0x{method.NativeCallback.MetadataToken.RID:x})");
+				}
 			}
 
 			void MoveFile (string source, string target)
@@ -99,7 +104,7 @@ ICollection<string> GetAssemblyPaths (AssemblyDefinition asm)
 			return paths;
 		}
 
-		CustomAttribute GetUnmanagedCallersOnlyAttribute (AssemblyDefinition targetAssembly, DirectoryAssemblyResolver resolver)
+		MethodDefinition GetUnmanagedCallersOnlyAttributeConstructor (DirectoryAssemblyResolver resolver)
 		{
 			AssemblyDefinition asm = resolver.Resolve ("System.Runtime.InteropServices");
 			TypeDefinition unmanagedCallersOnlyAttribute = null;
@@ -118,16 +123,24 @@ CustomAttribute GetUnmanagedCallersOnlyAttribute (AssemblyDefinition targetAssem
 				}
 			}
 
-			MethodDefinition attrConstructor = null;
+			if (unmanagedCallersOnlyAttribute == null) {
+				throw new InvalidOperationException ("Unable to find the System.Runtime.InteropServices.UnmanagedCallersOnlyAttribute type");
+			}
+
 			foreach (MethodDefinition md in unmanagedCallersOnlyAttribute.Methods) {
 				if (!md.IsConstructor) {
 					continue;
 				}
 
-				attrConstructor = md;
+				return md;
 			}
 
-			return new CustomAttribute (targetAssembly.MainModule.ImportReference (attrConstructor));
+			throw new InvalidOperationException ("Unable to find the System.Runtime.InteropServices.UnmanagedCallersOnlyAttribute type constructor");
+		}
+
+		CustomAttribute CreateImportedUnmanagedCallersOnlyAttribute (AssemblyDefinition targetAssembly, MethodDefinition unmanagedCallersOnlyAtributeCtor)
+		{
+			return new CustomAttribute (targetAssembly.MainModule.ImportReference (unmanagedCallersOnlyAtributeCtor));
 		}
 	}
 }

src/Xamarin.Android.Build.Tasks/Utilities/MarshalMethodsClassifier.cs

@@ -13,7 +13,7 @@ namespace Xamarin.Android.Tasks
 #if ENABLE_MARSHAL_METHODS
 	public sealed class MarshalMethodEntry
 	{
-		public TypeDefinition TopType             { get; }
+		public TypeDefinition DeclaringType       { get; }
 		public MethodDefinition NativeCallback    { get; }
 		public MethodDefinition Connector         { get; }
 		public MethodDefinition RegisteredMethod  { get; }
@@ -24,18 +24,27 @@ public sealed class MarshalMethodEntry
 		public string JniMethodSignature          { get; }
 
 		public MarshalMethodEntry (TypeDefinition topType, MethodDefinition nativeCallback, MethodDefinition connector, MethodDefinition
-		                           registeredMethod, MethodDefinition implementedMethod, FieldDefinition callbackField, string jniTypeName,
-		                           string jniName, string jniSignature)
+				registeredMethod, MethodDefinition implementedMethod, FieldDefinition callbackField, string jniTypeName,
+				string jniName, string jniSignature)
 		{
-			TopType = topType ?? throw new ArgumentNullException (nameof (topType));
+			DeclaringType = topType ?? throw new ArgumentNullException (nameof (topType));
 			NativeCallback = nativeCallback ?? throw new ArgumentNullException (nameof (nativeCallback));
 			Connector = connector ?? throw new ArgumentNullException (nameof (connector));
 			RegisteredMethod = registeredMethod ?? throw new ArgumentNullException (nameof (registeredMethod));
 			ImplementedMethod = implementedMethod ?? throw new ArgumentNullException (nameof (implementedMethod));
-			CallbackField = callbackField;
-			JniTypeName = jniTypeName;
-			JniMethodName = jniName;
-			JniMethodSignature = jniSignature;
+			CallbackField = callbackField; // we don't require the callback field to exist
+			JniTypeName = EnsureNonEmpty (jniTypeName, nameof (jniTypeName));
+			JniMethodName = EnsureNonEmpty (jniName, nameof (jniName));
+			JniMethodSignature = EnsureNonEmpty (jniSignature, nameof (jniSignature));
+		}
+
+		string EnsureNonEmpty (string s, string argName)
+		{
+			if (String.IsNullOrEmpty (s)) {
+				throw new ArgumentException ("must not be null or empty", argName);
+			}
+
+			return s;
 		}
 	}
 #endif

src/Xamarin.Android.Build.Tasks/Utilities/MarshalMethodsNativeAssemblyGenerator.cs

@@ -38,7 +38,7 @@ struct MarshalMethodsManagedClass
 
 		public ICollection<string> UniqueAssemblyNames                       { get; set; }
 		public int NumberOfAssembliesInApk                                   { get; set; }
-		public IDictionary<string, MarshalMethodEntry> MarshalMethods        { get; set; }
+		public IDictionary<string, IList<MarshalMethodEntry>> MarshalMethods { get; set; }
 
 		StructureInfo<TypeMappingReleaseNativeAssemblyGenerator.MonoImage> monoImage;
 		StructureInfo<MonoClass> monoClass;

src/Xamarin.Android.Build.Tasks/Utilities/MarshalMethodsState.cs

@@ -6,9 +6,9 @@ namespace Xamarin.Android.Tasks
 {
 	sealed class MarshalMethodsState
 	{
-		public IDictionary<string, MarshalMethodEntry> MarshalMethods        { get; }
+		public IDictionary<string, IList<MarshalMethodEntry>> MarshalMethods { get; }
 
-		public MarshalMethodsState (IDictionary<string, MarshalMethodEntry> marshalMethods)
+		public MarshalMethodsState (IDictionary<string, IList<MarshalMethodEntry>> marshalMethods)
 		{
 			MarshalMethods = marshalMethods ?? throw new ArgumentNullException (nameof (marshalMethods));
 		}