[jnimarshalmethod-gen] JavaInterop1 marshal methods (#1164)

Fixes: #1159

Context: c93fea0

`jnimarshalmethod-gen` is intended to generate marshal methods for
any type that that:

  * Has `[JavaCallable]` (tested in `Java.Interop.Export-Tests.dll`
    and c93fea0), or
  * Overrides a `virtual` method which has `[JniMethodSignature]`, or
  * Implements an interface method which has `[JniMethodSignature]`.

Thus, the intention was that it should generate marshal methods for
`Java.Base-Tests`:

	% dotnet bin/Debug-net7.0/jnimarshalmethod-gen.dll -v bin/TestDebug-net7.0/Java.Base-Tests.dll
	Unable to read assembly 'bin/TestDebug-net7.0/Java.Base-Tests.dll' with symbols. Retrying to load it without them.
	Preparing marshal method assembly 'Java.Base-Tests-JniMarshalMethods'
	Processing Java.BaseTests.JavaInvoker type
	Processing Java.BaseTests.MyRunnable type
	Processing Java.BaseTests.MyIntConsumer type
	Marshal method assembly 'Java.Base-Tests-JniMarshalMethods' created

Notably missing? No messages stating:

	Adding marshal method for …

Also missing?  `ikdasm bin/TestDebug-net7.0/Java.Base-Tests.dll`
showed that there were no `__RegisterNativeMembers()` methods emitted.

The `jnimarshalmethod-gen` invocation was a no-op!

The problems were twofold:

 1. It was only looking for methods with
    `Android.Runtime.RegisterAttribute`.  This was useful for
    Xamarin.Android (when we were trying to make it work), but
    doesn't work with Java.Base.  We need to *also* look for
    `Java.Interop.JniMethodSignature`.

    Relatedly, the attempt to use
    `registerAttribute.Constructor.Parameters` to determine parameter
    names didn't work; the parameter name was always `""`.

 2. A'la c93fea0, we need to ensure that the Java `native` methods
    we register are consistent with `jcw-gen` output.

Fix these two problems, which allows `jnimarshalmethod-gen` to now
emit marshal methods for types within `Java.Base-Tests.dll`.

Additionally, rework the `jnimarshalmethod-gen -f` logic to *remove*
the existing `__<$>_jni_marshal_methods` nested type when present.

build-tools/automation/templates/core-tests.yaml

@@ -146,6 +146,26 @@ steps:
   continueOnError: true
   retryCountOnTaskFailure: 1
 
+- task: DotNetCoreCLI@2
+  displayName: 'jnimarshalmethod-gen Java.Base-Tests.dll'
+  condition: or(eq('${{ parameters.runNativeDotnetTests }}', 'true'), eq('${{ parameters.runNativeTests }}', 'true'))
+  inputs:
+    command: custom
+    custom: bin/$(Build.Configuration)$(NetCoreTargetFrameworkPathSuffix)/jnimarshalmethod-gen.dll
+    arguments: bin/Test$(Build.Configuration)$(NetCoreTargetFrameworkPathSuffix)/Java.Base-Tests.dll -v -v --keeptemp
+  continueOnError: true
+  retryCountOnTaskFailure: 1
+
+- task: DotNetCoreCLI@2
+  displayName: 'Tests: Java.Base'
+  condition: or(eq('${{ parameters.runNativeDotnetTests }}', 'true'), eq('${{ parameters.runNativeTests }}', 'true'))
+  inputs:
+    command: test
+    testRunTitle: Java.Base ($(DotNetTargetFramework) - ${{ parameters.platformName }})
+    arguments: bin/Test$(Build.Configuration)$(NetCoreTargetFrameworkPathSuffix)/Java.Base-Tests.dll
+  continueOnError: true
+  retryCountOnTaskFailure: 1
+
 - task: DotNetCoreCLI@2
   displayName: 'Tests: java-source-utils'
   inputs:

tools/jnimarshalmethod-gen/App.cs

@@ -476,10 +476,14 @@ void CreateMarshalMethodAssembly (string path)
 					continue;
 
 				var existingMarshalMethodsType = td.GetNestedType (TypeMover.NestedName);
-				if (existingMarshalMethodsType != null && !forceRegeneration) {
-					Warning (Message.WarningMarshalMethodsTypeAlreadyExists, existingMarshalMethodsType.GetAssemblyQualifiedName (cache), assemblyName);
+				if (existingMarshalMethodsType != null) {
 
-					return;
+					if (forceRegeneration) {
+						td.NestedTypes.Remove (existingMarshalMethodsType);
+					} else {
+						Warning (Message.WarningMarshalMethodsTypeAlreadyExists, existingMarshalMethodsType.GetAssemblyQualifiedName (cache), assemblyName);
+						return;
+					}
 				}
 
 				if (Verbose)
@@ -512,7 +516,7 @@ void CreateMarshalMethodAssembly (string path)
 
 					if (exportObj != null) {
 						dynamic e = exportObj;
-						name = e.Name;
+						name = "n_" + methodName;
 						signature = e.Signature;
 					}
 					else {
@@ -550,15 +554,14 @@ void CreateMarshalMethodAssembly (string path)
 					Log (TraceLevel.Verbose, $"## Dumping contents of marshal method for `{td.FullName}::{method.Name}({string.Join (", ", method.GetParameters ().Select (p => p.ParameterType))})`:");
 					Console.WriteLine (lambda.ToCSharpCode ());
 #endif  // _DUMP_REGISTER_NATIVE_MEMBERS
-					name = export?.Name ?? method.Name;
 
 					var mmDef = assemblyBuilder.Compile (lambda);
 					mmDef.Name = name;
 					mmTypeDef.Methods.Add (mmDef);
 
 					signature = export?.Signature ?? builder.GetJniMethodSignature (method);
 
-					registrations.Add (new ExpressionMethodRegistration ("n_" + method.Name, signature, mmDef));
+					registrations.Add (new ExpressionMethodRegistration (name, signature, mmDef));
 
 					addedMethods.Add (methodName);
 				}
@@ -739,35 +742,19 @@ public static MethodDefinition GetMethodDefinition (this TypeDefinition td, Meth
 
 		static bool CheckMethod (MethodDefinition m, ref string name, ref string methodName, ref string signature)
 		{
-			foreach (var registerAttribute in m.GetCustomAttributes ("Android.Runtime.RegisterAttribute")) {
+			var registerAttrs = m.GetCustomAttributes ("Android.Runtime.RegisterAttribute")
+				.Concat (m.GetCustomAttributes ("Java.Interop.JniMethodSignatureAttribute"));
+			foreach (var registerAttribute in registerAttrs) {
 				if (registerAttribute == null || !registerAttribute.HasConstructorArguments)
 					continue;
 
-				var constructorParameters = registerAttribute.Constructor.Parameters.ToArray ();
-				var constructorArguments = registerAttribute.ConstructorArguments.ToArray ();
-
-				for (int i = 0; i < constructorArguments.Length; i++) {
-					switch (constructorParameters [i].Name) {
-					case "name":
-						name = constructorArguments [i].Value.ToString ();
-						break;
-					case "signature":
-						signature = constructorArguments [i].Value.ToString ();
-						break;
-					}
-
-				}
-
-				if ((string.IsNullOrEmpty (name) || string.IsNullOrEmpty (signature)) && constructorArguments.Length != 3)
+				if (registerAttribute.ConstructorArguments.Count < 2)
 					continue;
 
-				if (string.IsNullOrEmpty (name))
-					name = constructorArguments [0].Value.ToString ();
-
-				if (string.IsNullOrEmpty (signature))
-					signature = constructorArguments [1].Value.ToString ();
+				name        = registerAttribute.ConstructorArguments [0].Value.ToString ();
+				signature   = registerAttribute.ConstructorArguments [1].Value.ToString ();
 
-				if (string.IsNullOrEmpty (name) || string.IsNullOrEmpty (signature))
+				if ((string.IsNullOrEmpty (name) || string.IsNullOrEmpty (signature)))
 					continue;
 
 				methodName = MarshalMemberBuilder.GetMarshalMethodName (name, signature);
@@ -808,13 +795,14 @@ public static bool NeedsMarshalMethod (this MethodDefinition md, DirectoryAssemb
 					continue;
 				}
 
-				for (int i = 0; i < ifaceMap.TargetMethods.Length; i++)
+				for (int i = 0; i < ifaceMap.TargetMethods.Length; i++) {
 					if (ifaceMap.TargetMethods [i] == method) {
 						var imd = id.GetMethodDefinition (ifaceMap.InterfaceMethods [i]);
 
 						if (CheckMethod (imd, ref name, ref methodName, ref signature))
 							return true;
 					}
+				}
 			}
 
 			return false;