[Rgen] Add parsing of the ThreadSafe attr to the transformer.

src/rgen/Microsoft.Macios.Transformer/Attributes/ThreadSafeData.cs

@@ -0,0 +1,68 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.CodeAnalysis;
+
+namespace Microsoft.Macios.Transformer.Attributes;
+
+readonly struct ThreadSafeData : IEquatable<ThreadSafeData> {
+
+	public bool Safe { get; } = true;
+
+	public ThreadSafeData () : this (true) {}
+
+	public ThreadSafeData (bool safe)
+	{
+		Safe = safe;
+	}
+
+	public static bool TryParse (AttributeData attributeData,
+		[NotNullWhen (true)] out ThreadSafeData? data)
+	{
+		data = null;
+		var count = attributeData.ConstructorArguments.Length;
+		if (count == 0) {
+			data = new();
+			return true;
+		}
+		bool safe = true;
+		switch (count) {
+		case 1:
+			safe = (bool) attributeData.ConstructorArguments [0].Value!;
+			break;
+		default:
+			// 0 should not be an option..
+			return false;
+		}
+
+		data = new ThreadSafeData (safe);
+		return true;
+	}
+
+	public bool Equals (ThreadSafeData other)
+		=> Safe == other.Safe;
+
+	/// <inheritdoc />
+	public override bool Equals (object? obj)
+	{
+		return obj is ThreadSafeData other && Equals (other);
+	}
+
+	/// <inheritdoc />
+	public override int GetHashCode ()
+		=> HashCode.Combine (Safe);
+
+	public static bool operator == (ThreadSafeData x, ThreadSafeData y)
+	{
+		return x.Equals (y);
+	}
+
+	public static bool operator != (ThreadSafeData x, ThreadSafeData y)
+	{
+		return !(x == y);
+	}
+
+	public override string ToString ()
+		=> $"{{ ThreadSafe: {Safe} }}";
+}

src/rgen/Microsoft.Macios.Transformer/AttributesNames.cs

@@ -279,6 +279,11 @@ static class AttributesNames {
 	/// </summary>
 	[BindingFlag (AttributeTargets.Class | AttributeTargets.Interface)]
 	public const string TargetAttribute = "TargetAttribute";
+
+	/// <summary>
+	/// Flags the object as being thread safe.
+	/// </summary>
+	[BindingAttribute(typeof(BackingFieldTypeData), AttributeTargets.All)]
 	public const string ThreadSafeAttribute = "ThreadSafeAttribute";
 
 	/// <summary>

tests/rgen/Microsoft.Macios.Transformer.Tests/Attributes/ThreadSafeDataTests.cs

@@ -0,0 +1,92 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Collections;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.Macios.Generator.Extensions;
+using Microsoft.Macios.Transformer.Attributes;
+using Xamarin.Tests;
+using Xamarin.Utils;
+
+namespace Microsoft.Macios.Transformer.Tests.Attributes;
+
+public class ThreadSafeDataTests : BaseTransformerTestClass {
+
+	class TestDataTryCreate : IEnumerable<object []> {
+		public IEnumerator<object []> GetEnumerator ()
+		{
+			var path = "/some/random/path.cs";
+
+			const string threadSageMethod = @"
+using System;
+using Foundation;
+using ObjCRuntime;
+using UIKit;
+
+namespace Test;
+
+[NoTV]
+[MacCatalyst (13, 1)]
+[DisableDefaultCtor]
+[Abstract]
+[BaseType (typeof (NSObject))]
+interface UIFeedbackGenerator : UIInteraction {
+
+	[Export (""prepare""), ThreadSafe]
+	void Prepare ();
+}
+";
+
+			yield return [(Source: threadSageMethod, Path: path), new ThreadSafeData()];
+
+			const string notThreadSafeMethod = @"
+using System;
+using Foundation;
+using ObjCRuntime;
+using UIKit;
+
+namespace Test;
+
+[NoTV]
+[MacCatalyst (13, 1)]
+[DisableDefaultCtor]
+[Abstract]
+[BaseType (typeof (NSObject))]
+interface UIFeedbackGenerator : UIInteraction {
+
+	[Export (""prepare""), ThreadSafe (false)]
+	void Prepare ();
+}
+";
+
+			yield return [(Source: notThreadSafeMethod, Path: path), new ThreadSafeData(false)];
+
+		}
+
+		IEnumerator IEnumerable.GetEnumerator () => GetEnumerator ();
+	}
+
+	[Theory]
+	[AllSupportedPlatformsClassData<TestDataTryCreate>]
+	void TryCreateTests (ApplePlatform platform, (string Source, string Path) source, ThreadSafeData expectedData)
+	{
+		// create a compilation used to create the transformer
+		var compilation = CreateCompilation (platform, sources: source);
+		var syntaxTree = compilation.SyntaxTrees.ForSource (source);
+		Assert.NotNull (syntaxTree);
+
+		var semanticModel = compilation.GetSemanticModel (syntaxTree);
+		Assert.NotNull (semanticModel);
+
+		var declaration = syntaxTree.GetRoot ()
+			.DescendantNodes ().OfType<MethodDeclarationSyntax> ()
+			.FirstOrDefault ();
+		Assert.NotNull (declaration);
+
+		var symbol = semanticModel.GetDeclaredSymbol (declaration);
+		Assert.NotNull (symbol);
+		var attribute = symbol.GetAttribute<ThreadSafeData> (AttributesNames.ThreadSafeAttribute, ThreadSafeData.TryParse);
+		Assert.Equal (expectedData, attribute);
+	}
+}