Generated files (e.g, `Java.Interop.__TypeRegistrations.cs`) should mark themselves as auto-generated

[Youssef1313]

Android application type

Classic Xamarin.Android (MonoAndroid12.0, etc.), Android for .NET (net6.0-android, etc.)

Affected platform version

MonoAndroid13.0 and net6.0-android

Description

With a project where CA1812 and CA are enforced as errors, the following is observed:

##[error]src\Uno.UI.BindingHelper.Android\obj\Release\net6.0-android\generated\src\Java.Interop.__TypeRegistrations.cs(16,6): Error CA1825: Avoid unnecessary zero-length array allocations.  Use Array.Empty<string>() instead.
C:\a\1\s\src\Uno.UI.BindingHelper.Android\obj\Release\net6.0-android\generated\src\Java.Interop.__TypeRegistrations.cs(16,6): error CA1825: Avoid unnecessary zero-length array allocations.  Use Array.Empty<string>() instead. [C:\a\1\s\src\Uno.UI.BindingHelper.Android\Uno.UI.BindingHelper.Android.net6.csproj]
##[error]src\Uno.UI.BindingHelper.Android\obj\Release\net6.0-android\generated\src\Java.Interop.__TypeRegistrations.cs(18,6): Error CA1825: Avoid unnecessary zero-length array allocations.  Use Array.Empty<Converter<string, Type>>() instead.
C:\a\1\s\src\Uno.UI.BindingHelper.Android\obj\Release\net6.0-android\generated\src\Java.Interop.__TypeRegistrations.cs(18,6): error CA1825: Avoid unnecessary zero-length array allocations.  Use Array.Empty<Converter<string, Type>>() instead. [C:\a\1\s\src\Uno.UI.BindingHelper.Android\Uno.UI.BindingHelper.Android.net6.csproj]
##[error]src\Uno.UI.BindingHelper.Android\obj\Release\net6.0-android\generated\src\Uno.UI.UnoRecyclerView.cs(168,25): Error CA1812: 'UnoRecyclerViewInvoker' is an internal class that is apparently never instantiated. If so, remove the code from the assembly. If this class is intended to contain only static members, make it 'static' (Module in Visual Basic).
C:\a\1\s\src\Uno.UI.BindingHelper.Android\obj\Release\net6.0-android\generated\src\Uno.UI.UnoRecyclerView.cs(168,25): error CA1812: 'UnoRecyclerViewInvoker' is an internal class that is apparently never instantiated. If so, remove the code from the assembly. If this class is intended to contain only static members, make it 'static' (Module in Visual Basic). [C:\a\1\s\src\Uno.UI.BindingHelper.Android\Uno.UI.BindingHelper.Android.net6.csproj]
##[error]src\Uno.UI.BindingHelper.Android\obj\Release\net6.0-android\generated\src\Uno.UI.UnoViewGroup.cs(829,25): Error CA1812: 'UnoViewGroupInvoker' is an internal class that is apparently never instantiated. If so, remove the code from the assembly. If this class is intended to contain only static members, make it 'static' (Module in Visual Basic).
C:\a\1\s\src\Uno.UI.BindingHelper.Android\obj\Release\net6.0-android\generated\src\Uno.UI.UnoViewGroup.cs(829,25): error CA1812: 'UnoViewGroupInvoker' is an internal class that is apparently never instantiated. If so, remove the code from the assembly. If this class is intended to contain only static members, make it 'static' (Module in Visual Basic). [C:\a\1\s\src\Uno.UI.BindingHelper.Android\Uno.UI.BindingHelper.Android.net6.csproj]

1. These files should have // <auto-generated/> comment at the top so that Roslyn marks them as auto-generated and skips most analyzers for them.
2. The above violations should be fixed if possible.

Steps to Reproduce

Did you find any workaround?

No response

Relevant log output

No response

[jpobst]

Some examples of what a regular console .NET 6 program generates:

• .NETCoreApp,Version=v6.0.AssemblyAttributes.cs:

// <autogenerated />
using System;
...

• {application}.AssemblyInfo.cs:

//------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by a tool.
//     Runtime Version:4.0.30319.42000
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------
using System;
...

Using the longer version could also help with issues like dotnet/android#7449.

[jpobst]

Can you post a Java.Interop.__TypeRegistrations.cs that demonstrates the CA1825 warning? It looks like all the arrays should have content in them, unless your binding library doesn't bind any types or something? Or maybe all the types it binds are static?

Example:

		public static void RegisterPackages ()
		{
#if MONODROID_TIMING
			var start = DateTime.Now;
			Android.Util.Log.Info ("MonoDroid-Timing", "RegisterPackages start: " + (start - new DateTime (1970, 1, 1)).TotalMilliseconds);
#endif // def MONODROID_TIMING
			Java.Interop.TypeManager.RegisterPackages (
					new string[]{
						"com/google/common/flogger",
						"com/google/common/flogger/backend",
						"com/google/common/flogger/context",
						"com/google/common/flogger/parameter",
						"com/google/common/flogger/parser",
						"com/google/common/flogger/util",
					},
					new Converter<string, Type?>[]{
						lookup_com_google_common_flogger_package,
						lookup_com_google_common_flogger_backend_package,
						lookup_com_google_common_flogger_context_package,
						lookup_com_google_common_flogger_parameter_package,
						lookup_com_google_common_flogger_parser_package,
						lookup_com_google_common_flogger_util_package,
					});
#if MONODROID_TIMING
			var end = DateTime.Now;
			Android.Util.Log.Info ("MonoDroid-Timing", "RegisterPackages time: " + (end - new DateTime (1970, 1, 1)).TotalMilliseconds + " [elapsed: " + (end - start).TotalMilliseconds + " ms]");
#endif // def MONODROID_TIMING
		}

[Youssef1313]

@jpobst This is what I'm seeing:

using System;
using System.Collections.Generic;
using Android.Runtime;

namespace Java.Interop {

	partial class __TypeRegistrations {

		public static void RegisterPackages ()
		{
#if MONODROID_TIMING
			var start = DateTime.Now;
			Android.Util.Log.Info ("MonoDroid-Timing", "RegisterPackages start: " + (start - new DateTime (1970, 1, 1)).TotalMilliseconds);
#endif // def MONODROID_TIMING
			Java.Interop.TypeManager.RegisterPackages (
					new string[]{
					},
					new Converter<string, Type>[]{
					});
#if MONODROID_TIMING
			var end = DateTime.Now;
			Android.Util.Log.Info ("MonoDroid-Timing", "RegisterPackages time: " + (end - new DateTime (1970, 1, 1)).TotalMilliseconds + " [elapsed: " + (end - start).TotalMilliseconds + " ms]");
#endif // def MONODROID_TIMING
		}

#if NET5_0_OR_GREATER
		[System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessage ("Trimming", "IL2057")]
#endif
		static Type Lookup (string[] mappings, string javaType)
		{
			var managedType = Java.Interop.TypeManager.LookupTypeMapping (mappings, javaType);
			if (managedType == null)
				return null;
			return Type.GetType (managedType);
		}
	}
}