[generator] Fix xamarin-android/src/Mono.Android build

[jonpryor]

[generator] Fix xamarin-android/src/Mono.Android build

Context: a65d6fb
Context: dotnet/android#6939

dotnet/android#6939 attempted to bump to 05eddd9, which
promptly broke the build of src/Mono.Android, e.g.
src/Mono.Android/obj/Debug/net6.0/android-32/mcw/Android.Widget.GridLayout.cs:

/*       */ partial class GridLayout {
/*       */     partial class partial class LayoutParams {
/*       */         [Register ("rowSpec")]
/*       */         public Android.Widget.GridLayout.Spec? RowSpec {
/*       */             get {
/*       */                 const string __id = "rowSpec.Landroid/widget/GridLayout$Spec;";
/*       */                 var __v = _members.InstanceFields.GetObjectValue (__id, this);
/*       */                 return global::Java.Lang.Object.GetObject<Android.Widget.GridLayout.Spec> (__v.Handle, JniHandleOwnership.TransferLocalRef);
/*       */             }
/*       */             set {
/*       */                 const string __id = "rowSpec.Landroid/widget/GridLayout$Spec;";
/*       */                 IntPtr native_value = global::Android.Runtime.JNIEnv.ToLocalJniHandle (value);
/*       */                 try {
/* L 239 */                     _members.InstanceFields.SetValue (__id, this, new JniObjectReference (value));
/*       */                 } finally {
/* L 242 */                     global::Android.Runtime.JNIEnv.DeleteLocalRef (value);
/*       */                 }
/*       */             }
/*       */         }
/*       */     }
/*       */ }

due to compilation errors:

src/Mono.Android/obj/Debug/net6.0/android-32/mcw/Android.Widget.GridLayout.cs(239,77):
  error CS1503: Argument 1: cannot convert from 'Android.Widget.GridLayout.Spec' to 'System.IntPtr'
src/Mono.Android/obj/Debug/net6.0/android-32/mcw/Android.Widget.GridLayout.cs(242,54):
  error CS1503: Argument 1: cannot convert from 'Android.Widget.GridLayout.Spec' to 'System.IntPtr'

This was caused by BoundFieldAsProperty.cs not appropriately
setting arg to native_arg, so that the correct variable would be
cleaned up in the finally block.

There was another set of errors:

src/Mono.Android/obj/Release/net6.0/android-32/mcw/Android.Widget.ArrayAdapter.cs(525,53):
  error CS1503: Argument 1: cannot convert from 'Java.Lang.ICharSequence[]' to 'string[]?'

which was also caused by a65d6fb mis-refactoring
SourceWriterExtensions.cs, and overlooking the entire existence of
the CharSequence.ArrayToStringArray() method (oops).

Update generator so that xamarin-android once again builds, and add
unit tests to hit these particular code paths.

[jonpryor]

Not sure why I added this in the first place, and it's presence causes extra whitespace changes when comparing src/Mono.Android build output from pre- a65d6fb vs. post- a65d6fb…

[jpobst]

With a forthcoming unit test and a successful test merge to XA (dotnet/android#6939), this should be fine.

[jpobst]

Is ICharSequenceExtensions.ToStringArray used? It doesn't show up in the unit test output, whereas CharSequence.ArrayToStringArray does show up.

[jonpryor]

@jpobst asked:

Is ICharSequenceExtensions.ToStringArray used?

No. Not only is it not used, the entire "context" is "wrong"; compare the XAJavaInterop1-NRT binding of CharSequence[] Echo(CharSequence[]):

[Register ("Echo", "([Ljava/lang/CharSequence;)[Ljava/lang/CharSequence;", "")]
public static unsafe Java.Lang.ICharSequence[]? EchoFormatted (Java.Lang.ICharSequence[]? messages) => …

public static string[]? Echo (string[]? messages)
{
	var jlca_messages = CharSequence.ArrayFromStringArray (messages);
	Java.Lang.ICharSequence[]? __result = EchoFormatted (jlca_messages);
	var __rsval = CharSequence.ArrayToStringArray (__result);
	if (jlca_messages != null) foreach (var s in jlca_messages) s?.Dispose ();
	return __rsval;
}

(Aside: notice that XAJavaInterop1 uses both CharSequence.ArrayFromStringArray() and CharSequence.ArrayToStringArray().)

Compare to the JavaInterop1 binding of CharSequence[] Echo(CharSequence[]):

public static unsafe Java.Interop.JavaObjectArray<Java.Lang.ICharSequence>? Echo (Java.Lang.ICharSequence[]? messages) => …

public static Java.Interop.JavaObjectArray<string>? Echo (string[]? messages)
{
	var jlca_messages = ICharSequenceExtensions.ToCharSequenceArray (messages);
	Java.Interop.JavaObjectArray<Java.Lang.ICharSequence>? __result = Echo (jlca_messages);
	var __rsval = __result;
	if (jlca_messages != null) foreach (var s in jlca_messages) s?.Dispose ();
	return __rsval;
}

It's all manner of "wrong":

• XAJavaInterop1 has EchoFormatted() and Echo(); JavaInterop1 has Echo() overloads. Presumably the first method should be EchoFormatted()?

• As per a65d6fb, the messages argument should be a JavaObjectArray<ICharSequence>, not ICharSequence[]! (See also src/Java.Base-ref.cs from 968e0f5, for which the only occurrence of [] is as part of a params array.)

  Which implies that I'm doing something "wrong" with my Parameter creation?

• Shouldn't the return type of Echo() be string[]?

I think the fundamental problem here is that my attempted unit test "setup" is wrong.

[jonpryor]

"For comparison", if I update tests/generator-Tests/expected/StaticMethods/StaticMethod.xml:

diff --git a/tests/generator-Tests/expected/StaticMethods/StaticMethod.xml b/tests/generator-Tests/expected/StaticMethods/StaticMethod.xml
index 913f5e69..294ba933 100644
--- a/tests/generator-Tests/expected/StaticMethods/StaticMethod.xml
+++ b/tests/generator-Tests/expected/StaticMethods/StaticMethod.xml
@@ -13,6 +13,9 @@
       		</method>
       		<method abstract="false" deprecated="Deprecated please use methodAsString" final="false" name="Obsoletemethod" native="false" return="java.lang.String" static="true" synchronized="false" visibility="public">
       		</method>
+      		<method abstract="false" deprecated="not deprecated" final="false" name="echo" native="false" return="java.lang.CharSequence[]" static="true" synchronized="false" visibility="public">
+				<parameter name="m" type="java.lang.CharSequence[]" />
+      		</method>
 	    </class>
 	</package>
 </api>

and then run:

mkdir _x
dotnet bin/Debug-net6.0/generator.dll --codegen-target=JavaInterop1 -o _x tests/generator-Tests/expected/StaticMethods/StaticMethod.xml

then _x/Xamarin.Test.SomeObject.cs contains:

// Metadata.xml XPath method reference: path="/api/package[@name='xamarin.test']/class[@name='SomeObject']/method[@name='echo' and count(parameter)=1 and parameter[1][@type='java.lang.CharSequence[]']]"
public static unsafe Java.Interop.JavaObjectArray<Java.Lang.ICharSequence> Echo (Java.Interop.JavaObjectArray<Java.Lang.ICharSequence> m)
{
	const string __id = "echo.([Ljava/lang/CharSequence;)[Ljava/lang/CharSequence;";
	var native_m = global::Java.Interop.JniEnvironment.Arrays.CreateMarshalObjectArray<global::Java.Lang.ICharSequence> (m);
	try {
		JniArgumentValue* __args = stackalloc JniArgumentValue [1];
		__args [0] = new JniArgumentValue (native_m);
		var __rm = _members.StaticMethods.InvokeObjectMethod (__id, __args);
		return global::Java.Interop.JniEnvironment.Runtime.ValueManager.GetValue<global::Java.Interop.JavaObjectArray<Java.Lang.ICharSequence>>(ref __rm, JniObjectReferenceOptions.CopyAndDispose);
	} finally {
		if (native_m != null) {
			native_m.DisposeUnlessReferenced ();
		}
		global::System.GC.KeepAlive (m);
	}
}
public static Java.Interop.JavaObjectArray<string> Echo (Java.Interop.JavaObjectArray<string> m)
{
	Java.Interop.JavaObjectArray<Java.Lang.ICharSequence> __result = Echo (m);
	var __rsval = __result;
	return __rsval;
}

which is closer to what I expected, in that the java.lang.CharSequence[] parameter was bound as JavaObjectArray<ICharSequence> (and then the method body fumbles things by using CreateMarshalObjectArray(), for no reason?!).

However, it's still not named EchoFormatted().

[jonpryor]

Summarizing my previous two comments:

I think that the WriteMethodWithCharSequenceArrays() unit test is "wrong". It's not "close enough" to what the "full" XML pipeline does, and thus the output is kinda non-sensical, particularly with JavaInterop1 output.

I don't know how to fix it, offhand.

I should probably update StaticMethod.xml for this use case, if only to have a "full integration" pass. (Which still won't use ICharSequenceExtensions.ToStringArray(), but at least the output will be saner. Not sane yet, but saner.)

[jonpryor]

I've removed GetCharSequenceArrayToStringArrayMethodName() from the most recent update, and update WriteMethodWithCharSequenceArrays() to use ParseApiDefinition().