Adds a test for multiple nested forwarders in a row with copy/link (#2372)

The problematic scenario is if there's a "copy" assembly with a forwarder to a "link" assembly with a forwarder. The forwarder is for a nested class.
Test for https://github.com/dotnet/linker/issues/2359.

Also improved the test infra to print out errors from ilasm if they happen.

7 files changed, 177 insertions, 1 deletions

diff --git a/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/ImplementationLibrary.cs b/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/ImplementationLibrary.cs
index 211e2d14f..6ba555970 100644
--- a/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/ImplementationLibrary.cs
+++ b/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/ImplementationLibrary.cs
@@ -25,6 +25,10 @@ namespace Mono.Linker.Tests.Cases.TypeForwarding.Dependencies
 			public static int PropertyOnNestedType { get; set; }
 		}
 
+		public class ForwardedNestedType
+		{
+		}
+
 		public static int someField = 42;
 
 		public string GetSomeValue ()
@@ -33,6 +37,13 @@ namespace Mono.Linker.Tests.Cases.TypeForwarding.Dependencies
 		}
 	}
 
+	public class AnotherImplementationClass
+	{
+		public class ForwardedNestedType
+		{
+		}
+	}
+
 	[AttributeUsage (AttributeTargets.All)]
 	public class ImplementationLibraryAttribute : Attribute
 	{
diff --git a/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/NestedForwarderLibrary.il b/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/NestedForwarderLibrary.il
new file mode 100644
index 000000000..edb8ded47
--- /dev/null
+++ b/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/NestedForwarderLibrary.il
@@ -0,0 +1,31 @@
+.assembly extern mscorlib
+{
+}
+
+.assembly extern Implementation
+{
+}
+
+.assembly NestedForwarderLibrary
+{
+}
+
+.class extern forwarder Mono.Linker.Tests.Cases.TypeForwarding.Dependencies.ImplementationLibrary
+{
+  .assembly extern 'Implementation'
+}
+.class extern ForwardedNestedType
+{
+  .class extern 'Mono.Linker.Tests.Cases.TypeForwarding.Dependencies.ImplementationLibrary'
+}
+
+.class extern forwarder Mono.Linker.Tests.Cases.TypeForwarding.Dependencies.AnotherImplementationClass
+{
+  .assembly extern 'Implementation'
+}
+.class extern ForwardedNestedType
+{
+  .class extern 'Mono.Linker.Tests.Cases.TypeForwarding.Dependencies.ImplementationLibrary'
+}
+
+.module 'NestedForwarderLibrary.dll'
diff --git a/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/NestedForwarderLibrary_2.il b/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/NestedForwarderLibrary_2.il
new file mode 100644
index 000000000..2b0faefc6
--- /dev/null
+++ b/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/NestedForwarderLibrary_2.il
@@ -0,0 +1,31 @@
+.assembly extern mscorlib
+{
+}
+
+.assembly extern NestedForwarderLibrary
+{
+}
+
+.assembly NestedForwarderLibrary_2
+{
+}
+
+.class extern forwarder Mono.Linker.Tests.Cases.TypeForwarding.Dependencies.ImplementationLibrary
+{
+  .assembly extern 'NestedForwarderLibrary'
+}
+.class extern ForwardedNestedType
+{
+  .class extern 'Mono.Linker.Tests.Cases.TypeForwarding.Dependencies.ImplementationLibrary'
+}
+
+.class extern forwarder Mono.Linker.Tests.Cases.TypeForwarding.Dependencies.AnotherImplementationClass
+{
+  .assembly extern 'NestedForwarderLibrary'
+}
+.class extern ForwardedNestedType
+{
+  .class extern 'Mono.Linker.Tests.Cases.TypeForwarding.Dependencies.ImplementationLibrary'
+}
+
+.module 'NestedForwarderLibrary_2.dll'
diff --git a/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/ReferenceImplementationLibrary.cs b/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/ReferenceImplementationLibrary.cs
index 4ec420372..ac08d817a 100644
--- a/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/ReferenceImplementationLibrary.cs
+++ b/test/Mono.Linker.Tests.Cases/TypeForwarding/Dependencies/ReferenceImplementationLibrary.cs
@@ -27,6 +27,10 @@ namespace Mono.Linker.Tests.Cases.TypeForwarding.Dependencies
 			public static int PropertyOnNestedType { get; set; }
 		}
 
+		public class ForwardedNestedType
+		{
+		}
+
 		public static int someField = 0;
 
 		public string GetSomeValue ()
@@ -35,6 +39,13 @@ namespace Mono.Linker.Tests.Cases.TypeForwarding.Dependencies
 		}
 	}
 
+	public class AnotherImplementationClass
+	{
+		public class ForwardedNestedType
+		{
+		}
+	}
+
 	[AttributeUsage (AttributeTargets.All)]
 	public class ImplementationLibraryAttribute : Attribute
 	{
diff --git a/test/Mono.Linker.Tests.Cases/TypeForwarding/MultiForwardedTypesWithCopyUsed.cs b/test/Mono.Linker.Tests.Cases/TypeForwarding/MultiForwardedTypesWithCopyUsed.cs
new file mode 100644
index 000000000..e2e5c39bf
--- /dev/null
+++ b/test/Mono.Linker.Tests.Cases/TypeForwarding/MultiForwardedTypesWithCopyUsed.cs
@@ -0,0 +1,44 @@
+// 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 Mono.Linker.Tests.Cases.Expectations.Assertions;
+using Mono.Linker.Tests.Cases.Expectations.Metadata;
+using Mono.Linker.Tests.Cases.TypeForwarding.Dependencies;
+
+namespace Mono.Linker.Tests.Cases.TypeForwarding
+{
+	[SkipUnresolved (true)]
+
+	[SetupCompileBefore ("NestedForwarderLibrary_2.dll", new[] { "Dependencies/ReferenceImplementationLibrary.cs" }, defines: new[] { "INCLUDE_REFERENCE_IMPL" })]
+
+	// After compiling the test case we then replace the reference impl with implementation + type forwarder
+	[SetupCompileAfter ("Implementation.dll", new[] { "Dependencies/ImplementationLibrary.cs" })]
+	[SetupCompileAfter ("NestedForwarderLibrary.dll", new[] { "Dependencies/NestedForwarderLibrary.il" }, references: new[] { "Implementation.dll" })]
+	[SetupCompileAfter ("NestedForwarderLibrary_2.dll", new[] { "Dependencies/NestedForwarderLibrary_2.il" }, references: new[] { "NestedForwarderLibrary.dll" })]
+
+	[SetupLinkerAction ("copy", "test")]
+	[SetupLinkerAction ("copy", "NestedForwarderLibrary_2")]
+	[SetupLinkerAction ("copyused", "NestedForwarderLibrary")]
+	[SetupLinkerAction ("copyused", "Implementation")]
+
+	// https://github.com/dotnet/linker/issues/2359
+	// One of the type forwarders in NestedForwarderLibrary will not be kept.
+	// Which one depends on order.
+	//[KeptTypeInAssembly ("NestedForwarderLibrary.dll", typeof (ImplementationLibrary.ForwardedNestedType))]
+	//[KeptTypeInAssembly ("NestedForwarderLibrary.dll", typeof (AnotherImplementationClass.ForwardedNestedType))]
+	//[KeptTypeInAssembly ("NestedForwarderLibrary_2.dll", typeof (ImplementationLibrary.ForwardedNestedType))]
+	//[KeptTypeInAssembly ("NestedForwarderLibrary_2.dll", typeof (AnotherImplementationClass.ForwardedNestedType))]
+	[KeptTypeInAssembly ("Implementation.dll", typeof (ImplementationLibrary.ForwardedNestedType))]
+	[KeptTypeInAssembly ("Implementation.dll", typeof (AnotherImplementationClass.ForwardedNestedType))]
+
+	[KeptMember (".ctor()")]
+	class MultiForwardedTypesWithCopyUsed
+	{
+		static void Main ()
+		{
+			Console.WriteLine (typeof (ImplementationLibrary.ForwardedNestedType).FullName);
+			Console.WriteLine (typeof (AnotherImplementationClass.ForwardedNestedType).FullName);
+		}
+	}
+}
diff --git a/test/Mono.Linker.Tests.Cases/TypeForwarding/MultiForwardedTypesWithLink.cs b/test/Mono.Linker.Tests.Cases/TypeForwarding/MultiForwardedTypesWithLink.cs
new file mode 100644
index 000000000..2d61e1e6b
--- /dev/null
+++ b/test/Mono.Linker.Tests.Cases/TypeForwarding/MultiForwardedTypesWithLink.cs
@@ -0,0 +1,44 @@
+// 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 Mono.Linker.Tests.Cases.Expectations.Assertions;
+using Mono.Linker.Tests.Cases.Expectations.Metadata;
+using Mono.Linker.Tests.Cases.TypeForwarding.Dependencies;
+
+namespace Mono.Linker.Tests.Cases.TypeForwarding
+{
+	[SkipUnresolved (true)]
+
+	[SetupCompileBefore ("NestedForwarderLibrary_2.dll", new[] { "Dependencies/ReferenceImplementationLibrary.cs" }, defines: new[] { "INCLUDE_REFERENCE_IMPL" })]
+
+	// After compiling the test case we then replace the reference impl with implementation + type forwarder
+	[SetupCompileAfter ("Implementation.dll", new[] { "Dependencies/ImplementationLibrary.cs" })]
+	[SetupCompileAfter ("NestedForwarderLibrary.dll", new[] { "Dependencies/NestedForwarderLibrary.il" }, references: new[] { "Implementation.dll" })]
+	[SetupCompileAfter ("NestedForwarderLibrary_2.dll", new[] { "Dependencies/NestedForwarderLibrary_2.il" }, references: new[] { "NestedForwarderLibrary.dll" })]
+
+	[SetupLinkerAction ("copy", "test")]
+	[SetupLinkerAction ("copy", "NestedForwarderLibrary_2")]
+	[SetupLinkerAction ("link", "NestedForwarderLibrary")]
+	[SetupLinkerAction ("link", "Implementation")]
+
+	// https://github.com/dotnet/linker/issues/2359
+	// One of the type forwarders in NestedForwarderLibrary will not be kept.
+	// Which one depends on order.
+	//[KeptTypeInAssembly ("NestedForwarderLibrary.dll", typeof (ImplementationLibrary.ForwardedNestedType))]
+	//[KeptTypeInAssembly ("NestedForwarderLibrary.dll", typeof (AnotherImplementationClass.ForwardedNestedType))]
+	//[KeptTypeInAssembly ("NestedForwarderLibrary_2.dll", typeof (ImplementationLibrary.ForwardedNestedType))]
+	//[KeptTypeInAssembly ("NestedForwarderLibrary_2.dll", typeof (AnotherImplementationClass.ForwardedNestedType))]
+	[KeptTypeInAssembly ("Implementation.dll", typeof (ImplementationLibrary.ForwardedNestedType))]
+	[KeptTypeInAssembly ("Implementation.dll", typeof (AnotherImplementationClass.ForwardedNestedType))]
+
+	[KeptMember (".ctor()")]
+	class MultiForwardedTypesWithLink
+	{
+		static void Main ()
+		{
+			Console.WriteLine (typeof (ImplementationLibrary.ForwardedNestedType).FullName);
+			Console.WriteLine (typeof (AnotherImplementationClass.ForwardedNestedType).FullName);
+		}
+	}
+}
diff --git a/test/Mono.Linker.Tests/TestCasesRunner/ILCompiler.cs b/test/Mono.Linker.Tests/TestCasesRunner/ILCompiler.cs
index 52e876694..f2aba174d 100644
--- a/test/Mono.Linker.Tests/TestCasesRunner/ILCompiler.cs
+++ b/test/Mono.Linker.Tests/TestCasesRunner/ILCompiler.cs
@@ -15,16 +15,20 @@ namespace Mono.Linker.Tests.TestCasesRunner
 		public NPath Compile (CompilerOptions options)
 		{
 			var capturedOutput = new List<string> ();
+			var capturedError = new List<string> ();
 			var process = new Process ();
 			SetupProcess (process, options);
 			process.StartInfo.RedirectStandardOutput = true;
+			process.StartInfo.RedirectStandardError = true;
 			process.OutputDataReceived += (sender, args) => capturedOutput.Add (args.Data);
+			process.ErrorDataReceived += (sender, args) => capturedError.Add (args.Data);
 			process.Start ();
 			process.BeginOutputReadLine ();
+			process.BeginErrorReadLine ();
 			process.WaitForExit ();
 
 			if (process.ExitCode != 0) {
-				Assert.Fail ($"Failed to compile IL assembly : {options.OutputPath}\n{capturedOutput.Aggregate ((buff, s) => buff + Environment.NewLine + s)}");
+				Assert.Fail ($"Failed to compile IL assembly : {options.OutputPath}\n{capturedOutput.Aggregate ((buff, s) => buff + Environment.NewLine + s)}{capturedError.Aggregate ((buff, s) => buff + Environment.NewLine + s)}");
 			}
 
 			return options.OutputPath;