[arkit] Add ARAnchorCopying protocol (#4523)

Even if empty this protocol will help with tests and subclasses.

src/arkit.cs

@@ -144,11 +144,20 @@ namespace ARKit {
 		Mapped,
 	}
 
+	[iOS (12,0)]
+	[NoWatch, NoTV, NoMac]
+	[Protocol]
+	[Advice ("To conform to 'ARAnchorCopying' you need to implement:\n'[Export (\"initWithAnchor:\")]'\n'public YourConstructor (ARAnchor anchor)'")]
+	interface ARAnchorCopying : NSCopying {
+		// Constructors in interfaces are not possible in C#
+		// @required -(instancetype _Nonnull)initWithAnchor:(ARAnchor * _Nonnull)anchor;
+	}
+
 	[iOS (11,0)]
 	[NoWatch, NoTV, NoMac]
 	[BaseType (typeof (NSObject))]
 	[DisableDefaultCtor]
-	interface ARAnchor : NSCopying, NSSecureCoding {
+	interface ARAnchor : ARAnchorCopying, NSSecureCoding {
 
 		[NullAllowed, Export ("identifier")]
 		NSUuid Identifier { get; }

tests/introspection/ApiTypoTest.cs

@@ -62,6 +62,10 @@ namespace Introspection
 			return SkipAllowed (methodName.DeclaringType.Name, methodName.Name, typo);
 		}
 
+		readonly HashSet<string> allowedRule3 = new HashSet<string> {
+			"IARAnchorCopying", // We're showing a code snippet in the 'Advice' message and that shouldn't end with a dot.
+		};
+
 		HashSet<string> allowedMemberRule4 = new HashSet<string> {
 			"Platform",
 			"PlatformHelper",
@@ -944,8 +948,10 @@ namespace Introspection
 
 					// Rule 3: https://github.com/xamarin/xamarin-macios/wiki/BINDINGS#rule-3
 					if (!message.EndsWith (".", StringComparison.Ordinal)) {
-						ReportError ("[Rule 3] Missing '.' in attribute's message: \"{0}\" - {1}", message, memberAndType);
-						totalErrors++;
+						if (!allowedRule3.Contains (typeName)) {
+							ReportError ("[Rule 3] Missing '.' in attribute's message: \"{0}\" - {1}", message, memberAndType);
+							totalErrors++;
+						}
 					}
 
 					// Rule 4: https://github.com/xamarin/xamarin-macios/wiki/BINDINGS#rule-4

tests/xtro-sharpie/iOS-ARKit.ignore

@@ -5,7 +5,3 @@
 !wrong-simd-missing-marshaldirective! System.IntPtr ARKit.ARPlaneGeometry::GetRawTextureCoordinates(): simd type: simd_float2
 !wrong-simd-missing-marshaldirective! System.IntPtr ARKit.ARPlaneGeometry::GetRawVertices(): simd type: simd_float3
 !wrong-simd-missing-marshaldirective! System.IntPtr ARKit.ARPointCloud::GetRawPoints(): simd type: simd_float3
-
-# Protocol inlined in ARAnchor (constructor in protocol)
-!missing-protocol! ARAnchorCopying not bound
-!missing-protocol-conformance! ARAnchor should conform to ARAnchorCopying