[RGen] Provide factory method for Unsafe.AsRef methods.

src/rgen/Microsoft.Macios.Generator/Emitters/BindingSyntaxFactory.cs

@@ -223,4 +223,21 @@ internal static TypeSyntax GetIdentifierName (string []? @namespace, string @cla
 	/// <returns>The identifier name expression for a given class.</returns>
 	internal static TypeSyntax GetIdentifierName (string @class)
 		=> IdentifierName (@class);
+
+	/// <summary>
+	/// Create the needed expression to call the AsRef method from the Unsafe class.
+	/// </summary>
+	/// <param name="objectType">The target type for get the ref from.</param>
+	/// <param name="arguments">The arguments to pass to the AsRef method.</param>
+	/// <returns>The needed expression to call the AsRef method.</returns>
+	internal static ExpressionSyntax AsRef (string objectType, ImmutableArray<ArgumentSyntax> arguments)
+	{
+		var unsafeType = GetIdentifierName (
+			@namespace: ["System", "Runtime", "CompilerServices"],
+			@class: "Unsafe",
+			isGlobal: true);
+		var argsList = ArgumentList (SeparatedList<ArgumentSyntax> (arguments.ToSyntaxNodeOrTokenArray ()));
+		return StaticInvocationGenericExpression (unsafeType, "AsRef",
+			objectType, argsList);
+	}
 }

tests/rgen/Microsoft.Macios.Generator.Tests/Emitters/BindingSyntaxFactoryRuntimeTests.cs

@@ -900,4 +900,36 @@ void GetIdentifierNameTests (string []? @namespace, string @class, bool isGlobal
 		Assert.Equal (expectedDeclaration, declaration.ToFullString ());
 	}
 
+	class TestDataAsRefTests : IEnumerable<object []> {
+		public IEnumerator<object []> GetEnumerator ()
+		{
+			yield return [
+				"NSObject",
+				ImmutableArray.Create (
+					Argument (IdentifierName ("arg1"))
+				),
+				"global::System.Runtime.CompilerServices.Unsafe.AsRef<NSObject> (arg1)"
+			];
+
+			yield return [
+				"NSString",
+				ImmutableArray.Create (
+					Argument (IdentifierName ("arg1")),
+					Argument (IdentifierName ("arg2")),
+					Argument (IdentifierName ("arg3"))),
+				"global::System.Runtime.CompilerServices.Unsafe.AsRef<NSString> (arg1, arg2, arg3)"
+			];
+		}
+
+		IEnumerator IEnumerable.GetEnumerator () => GetEnumerator ();
+	}
+
+	[Theory]
+	[ClassData (typeof (TestDataAsRefTests))]
+	void AsRefTests (string objectType, ImmutableArray<ArgumentSyntax> arguments, string expectedDeclaration)
+	{
+		var declaration = AsRef (objectType, arguments);
+		Assert.Equal (expectedDeclaration, declaration.ToFullString ());
+	}
+
 }