Add the GeneratedCode Attribute to the Resource Designer classes.

Context dotnet#8381

We generate a Resource Designer assembly and an Intermediate
source file at build time. Both of these contain classes which
should have the `GeneratedCode` Attribute. So lets add it.
The version will be the same as the build assembly used to generate it.

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

@@ -123,6 +123,12 @@ bool Run (DirectoryAssemblyResolver res)
 			TypeReference e = ImportType ("System.ComponentModel.EditorBrowsableState", module, netstandardDef.MainModule);
 			var editorBrowserAttr = new CustomAttribute (editorBrowserConstructor);
 			editorBrowserAttr.ConstructorArguments.Add (new CustomAttributeArgument (e, System.ComponentModel.EditorBrowsableState.Never));
+
+			MethodReference generatedCodeConstructor = ImportCustomAttributeConstructor (cache, "System.CodeDom.Compiler.GeneratedCodeAttribute", module, netstandardDef.MainModule, argCount: 2);
+			var generatedCodeAttr = new CustomAttribute (generatedCodeConstructor);
+			generatedCodeAttr.ConstructorArguments.Add (new CustomAttributeArgument (module.TypeSystem.String, nameof(GenerateResourceDesignerAssembly)));
+			var version = typeof(GenerateResourceDesignerAssembly).Assembly.GetName().Version;
+			generatedCodeAttr.ConstructorArguments.Add (new CustomAttributeArgument (module.TypeSystem.String, version.ToString ()));
 
 			var att = TypeAttributes.AutoClass | TypeAttributes.AnsiClass | TypeAttributes.Public | TypeAttributes.BeforeFieldInit;
 
@@ -139,6 +145,7 @@ bool Run (DirectoryAssemblyResolver res)
 			);
 			CreateCtor (cache, resourceDesigner, module);
 			resourceDesigner.CustomAttributes.Add (editorBrowserAttr);
+			resourceDesigner.CustomAttributes.Add (generatedCodeAttr);
 			module.Types.Add (resourceDesigner);
 			TypeDefinition constDesigner = null;
 			if (IsApplication) {
@@ -152,6 +159,7 @@ bool Run (DirectoryAssemblyResolver res)
 				);
 				CreateCtor (cache, constDesigner, module);
 				constDesigner.CustomAttributes.Add (editorBrowserAttr);
+				constDesigner.CustomAttributes.Add (generatedCodeAttr);
 				module.Types.Add (constDesigner);
 			}
 

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

@@ -21,13 +21,15 @@ public class GenerateResourceDesignerIntermediateClass : AndroidTask
 // </auto-generated>
 //------------------------------------------------------------------------------
 using System;
+using System.CodeDom.Compiler;
 
 namespace %NAMESPACE% {
 	#pragma warning disable IDE0002
 	/// <summary>
 	/// Android Resource Designer class.
 	/// Exposes the Android Resource designer assembly into the project Namespace.
 	/// </summary>
+	[GeneratedCode(""%TOOL%"", ""%VERSION%"")]
 	public partial class Resource : %BASECLASS% {
 	}
 	#pragma warning restore IDE0002
@@ -40,6 +42,7 @@ public partial class Resource : %BASECLASS% {
 //------------------------------------------------------------------------------
 namespace %NAMESPACE%
 
+[<GeneratedCode(""%TOOL%"", ""%VERSION%"")>]
 type Resource = %BASECLASS%
 ";
 
@@ -54,11 +57,19 @@ public override bool RunTask ()
 			//bool isVB = string.Equals (extension, ".vb", StringComparison.OrdinalIgnoreCase);
 			bool isFSharp = string.Equals (language, "F#", StringComparison.OrdinalIgnoreCase);
 			bool isCSharp = string.Equals (language, "C#", StringComparison.OrdinalIgnoreCase);
+			var version = typeof(GenerateResourceDesignerIntermediateClass).Assembly.GetName().Version;
 			string template = "";
-			if (isCSharp)
-				template = CSharpTemplate.Replace ("%NAMESPACE%", Namespace).Replace ("%BASECLASS%", ns);
-			else if (isFSharp)
-				template = FSharpTemplate.Replace ("%NAMESPACE%", Namespace).Replace ("%BASECLASS%", ns);
+			if (isCSharp) {
+				template = CSharpTemplate.Replace ("%NAMESPACE%", Namespace)
+					.Replace ("%BASECLASS%", ns)
+					.Replace ("%VERSION%", version.ToString ())
+					.Replace ("%TOOL%", nameof (GenerateResourceDesignerIntermediateClass));
+			} else if (isFSharp) {
+				template = FSharpTemplate.Replace ("%NAMESPACE%", Namespace)
+					.Replace ("%BASECLASS%", ns)
+					.Replace ("%VERSION%", version.ToString ())
+					.Replace ("%TOOL%", nameof (GenerateResourceDesignerIntermediateClass));
+			}
 
 			Files.CopyIfStringChanged (template, OutputFile.ItemSpec);
 			return !Log.HasLoggedErrors;