Add some tests for by ref type data flow (#2407)

Author: vitek-karas

test/Mono.Linker.Tests.Cases/DataFlow/MethodByRefParameterDataFlow.cs

@@ -0,0 +1,65 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using Mono.Linker.Tests.Cases.Expectations.Assertions;
+using Mono.Linker.Tests.Cases.Expectations.Helpers;
+using Mono.Linker.Tests.Cases.Expectations.Metadata;
+
+namespace Mono.Linker.Tests.Cases.DataFlow
+{
+	[SkipKeptItemsValidation]
+	[ExpectedNoWarnings]
+	class MethodByRefParameterDataFlow
+	{
+		public static void Main ()
+		{
+			Type typeWithMethods = _fieldWithMethods;
+
+			TestAssignStaticToAnnotatedRefParameter (ref typeWithMethods);
+			TestAssignParameterToAnnotatedRefParameter (ref typeWithMethods, typeof (TestType));
+		}
+
+		[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)]
+		static Type _fieldWithMethods = null;
+
+		[ExpectedWarning ("IL2026", "Message for --TestType.Requires--")]
+
+		// https://github.com/dotnet/linker/issues/2158
+		// The type.GetMethods call generates a warning because we're not able to correctly track the value of the "this".
+		// (there's a ldind.ref insruction here which we currently don't handle and the "this" becomes unknown)
+		[ExpectedWarning ("IL2065")]
+		static void TestAssignStaticToAnnotatedRefParameter ([DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)] ref Type type)
+		{
+			type = typeof (TestTypeWithRequires);
+			type.GetMethods (); // Should not warn
+		}
+
+		// The warning message is REALLY confusing (basically wrong) since it talks about "calling the method with wrong argument"
+		// which is definitely not the case here.
+		[ExpectedWarning ("IL2067", "typeWithFields")]
+
+		// https://github.com/dotnet/linker/issues/2158
+		// The type.GetMethods call generates a warning because we're not able to correctly track the value of the "this".
+		// (there's a ldind.ref insruction here which we currently don't handle and the "this" becomes unknown)
+		[ExpectedWarning ("IL2065")]
+		static void TestAssignParameterToAnnotatedRefParameter (
+			[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)] ref Type type,
+			[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicFields)] Type typeWithFields)
+		{
+			type = typeWithFields; // Should warn
+			type.GetMethods (); // Should not warn
+		}
+
+		class TestTypeWithRequires
+		{
+			[RequiresUnreferencedCode ("Message for --TestType.Requires--")]
+			public static void Requires () { }
+		}
+
+		class TestType
+		{
+		}
+	}
+}

test/Mono.Linker.Tests.Cases/DataFlow/MethodByRefReturnDataFlow.cs

@@ -0,0 +1,49 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using Mono.Linker.Tests.Cases.Expectations.Assertions;
+using Mono.Linker.Tests.Cases.Expectations.Helpers;
+using Mono.Linker.Tests.Cases.Expectations.Metadata;
+
+namespace Mono.Linker.Tests.Cases.DataFlow
+{
+	[SkipKeptItemsValidation]
+	[ExpectedNoWarnings]
+	public class MethodByRefReturnDataFlow
+	{
+		public static void Main ()
+		{
+			ReturnAnnotatedTypeReferenceAsUnannotated ();
+			AssignToAnnotatedTypeReference ();
+		}
+
+		[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)]
+		static Type _annotatedField;
+
+		// This should warn, as assiging to the return ref Type will assign value to the annotated field
+		// but the annotation is not propagated
+		// https://github.com/dotnet/linker/issues/2158
+		// [ExpectedWarning("IL????")]
+		static ref Type ReturnAnnotatedTypeReferenceAsUnannotated () { return ref _annotatedField; }
+
+		[return: DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)]
+		static ref Type ReturnAnnotatedTypeReferenceAsAnnotated () { return ref _annotatedField; }
+
+		// https://github.com/dotnet/linker/issues/2158
+		// [ExpectedWarning("IL2026", "Message for --TestType.Requires--")]
+		static void AssignToAnnotatedTypeReference ()
+		{
+			ref Type typeShouldHaveAllMethods = ref ReturnAnnotatedTypeReferenceAsAnnotated ();
+			typeShouldHaveAllMethods = typeof (TestTypeWithRequires); // This should apply the annotation -> cause IL2026 due to RUC method
+			_annotatedField.GetMethods (); // Doesn't warn, but now contains typeof(TestType) - no warning here is correct
+		}
+
+		public class TestTypeWithRequires
+		{
+			[RequiresUnreferencedCode ("Message for --TestType.Requires--")]
+			public static void Requires () { }
+		}
+	}
+}

test/Mono.Linker.Tests.Cases/DataFlow/MethodParametersDataFlow.cs

@@ -36,6 +36,8 @@ public static void Main ()
 			instance.WriteToParameterOnInstanceMethod (null);
 			instance.LongWriteToParameterOnInstanceMethod (0, 0, 0, 0, null);
 			instance.UnsupportedParameterType (null);
+
+			TestParameterOverwrite (typeof (TestType));
 		}
 
 		// Validate the error message when annotated parameter is passed to another annotated parameter
@@ -223,6 +225,16 @@ private static void RequirePublicParameterlessConstructorAndNothing (
 		{
 		}
 
+		[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)]
+		static Type _fieldWithMethods;
+
+		[ExpectedWarning ("IL2077", nameof (_fieldWithMethods))]
+		static void TestParameterOverwrite ([DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicFields)] Type type)
+		{
+			type = _fieldWithMethods;
+			type.GetFields ();
+		}
+
 		class TestType
 		{
 			public TestType () { }