Add runtime async tests for catching non-Exception throws

src/tests/async/runtime-wrapped-exception/NoWrapThrowers.cs

@@ -0,0 +1,46 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Runtime.CompilerServices;
+using System.Threading.Tasks;
+
+// This assembly opts OUT of wrapping non-Exception throws, in contrast to the
+// C# default (WrapNonExceptionThrows = true) used by the main test assembly and
+// by CoreLib. The async methods below are otherwise identical to the ones in the
+// main test assembly; keeping them in a separate assembly is the only way to
+// exercise the WrapNonExceptionThrows = false configuration, since the setting is
+// assembly-scoped and decided by the frame that catches the exception.
+[assembly: RuntimeCompatibility(WrapNonExceptionThrows = false)]
+
+public static class NoWrapThrowers
+{
+    // Runtime async (async2) throwing a non-Exception after suspending.
+    public static async Task ThrowAfterYieldAsync2()
+    {
+        await Task.Yield();
+        NonExceptionThrower.ThrowNonException();
+    }
+
+    // Compiler state machine (async1) throwing a non-Exception after suspending.
+    [RuntimeAsyncMethodGeneration(false)]
+    public static async Task ThrowAfterYieldAsync1()
+    {
+        await Task.Yield();
+        NonExceptionThrower.ThrowNonException();
+    }
+
+    // Runtime async (async2) throwing a non-Exception before suspending.
+    public static async Task ThrowBeforeYieldAsync2()
+    {
+        NonExceptionThrower.ThrowNonException();
+        await Task.Yield();
+    }
+
+    // Compiler state machine (async1) throwing a non-Exception before suspending.
+    [RuntimeAsyncMethodGeneration(false)]
+    public static async Task ThrowBeforeYieldAsync1()
+    {
+        NonExceptionThrower.ThrowNonException();
+        await Task.Yield();
+    }
+}

src/tests/async/runtime-wrapped-exception/NoWrapThrowers.csproj

@@ -0,0 +1,6 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <ItemGroup>
+    <Compile Include="NoWrapThrowers.cs" />
+    <ProjectReference Include="NonExceptionThrower.ilproj" />
+  </ItemGroup>
+</Project>

src/tests/async/runtime-wrapped-exception/NonExceptionThrower.il

@@ -0,0 +1,24 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+// Helper that throws an object which does not derive from System.Exception.
+// This is only expressible in IL, so it lives in its own IL assembly. The thrown
+// object (a string) is what a catch handler in a WrapNonExceptionThrows=true
+// assembly observes as RuntimeWrappedException.WrappedException.
+
+.assembly extern System.Runtime { .publickeytoken = (B0 3F 5F 7F 11 D5 0A 3A) .ver 4:0:0:0 }
+
+.assembly NonExceptionThrower
+{
+}
+
+.class public auto ansi abstract sealed beforefieldinit NonExceptionThrower
+       extends [System.Runtime]System.Object
+{
+    .method public hidebysig static void ThrowNonException() cil managed noinlining
+    {
+        .maxstack 8
+        ldstr "A non-Exception object thrown from IL"
+        throw
+    }
+}

src/tests/async/runtime-wrapped-exception/NonExceptionThrower.ilproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk.IL">
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+  </PropertyGroup>
+  <ItemGroup>
+    <!-- The C# helper attribute injected by the directory props is not applicable to IL. -->
+    <Compile Remove="..\RuntimeAsyncMethodGenerationAttribute.cs" />
+    <Compile Include="NonExceptionThrower.il" />
+  </ItemGroup>
+</Project>

src/tests/async/runtime-wrapped-exception/runtime-wrapped-exception.cs

@@ -0,0 +1,125 @@
+// 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.Runtime.CompilerServices;
+using System.Threading.Tasks;
+using Xunit;
+
+// Regression tests for https://github.com/dotnet/runtime/issues/123194.
+//
+// IL allows throwing an object that does not derive from System.Exception. When
+// such an object propagates into a catch handler, it is (or is not) wrapped in a
+// RuntimeWrappedException depending on the RuntimeCompatibilityAttribute
+// WrapNonExceptionThrows setting of the assembly that owns the catch handler.
+//
+// The goal of runtime async (async2) is to match the traditional compiler
+// generated state machine (async1) behavior. These tests exercise both async
+// forms (via [RuntimeAsyncMethodGeneration]) throwing a non-Exception object,
+// once from an assembly with WrapNonExceptionThrows = true (this assembly, which
+// matches the C# default and CoreLib) and once from an assembly with
+// WrapNonExceptionThrows = false (NoWrapThrowers), for throws both before and
+// after a suspension point.
+public class RuntimeAsyncNonExceptionThrows
+{
+    private const string ThrownObject = "A non-Exception object thrown from IL";
+
+    // WrapNonExceptionThrows = true (this assembly): the non-Exception is observed
+    // as a RuntimeWrappedException by the awaiting caller for both async forms.
+
+    [Fact]
+    public static void CatchAfterYield_Async2()
+        => AssertNonExceptionWrapped(ThrowAfterYieldAsync2);
+
+    [Fact]
+    public static void CatchAfterYield_Async1()
+        => AssertNonExceptionWrapped(ThrowAfterYieldAsync1);
+
+    [Fact]
+    public static void CatchBeforeYield_Async2()
+        => AssertNonExceptionWrapped(ThrowBeforeYieldAsync2);
+
+    [Fact]
+    public static void CatchBeforeYield_Async1()
+        => AssertNonExceptionWrapped(ThrowBeforeYieldAsync1);
+
+    // WrapNonExceptionThrows = false (NoWrapThrowers assembly).
+
+    [Fact]
+    public static void CatchAfterYield_NoWrap_Async2()
+        => AssertNonExceptionWrapped(NoWrapThrowers.ThrowAfterYieldAsync2);
+
+    // async2 and async1 behave differently for a non-Exception thrown after a
+    // suspension point in a WrapNonExceptionThrows = false assembly:
+    //   * async2 faults the returned Task with a RuntimeWrappedException, which the
+    //     caller observes just like the wrap=true case above.
+    //   * async1 lets the raw non-Exception escape the resumed state machine onto
+    //     the thread pool where it becomes an unhandled exception and crashes the
+    //     process, so it can never be observed by the caller.
+    // async1 behavior here is terminal to the process, thus we will not test it:
+    //
+    // [Fact]
+    // public static void CatchAfterYield_NoWrap_Async1()
+    //     => AssertNonExceptionWrapped(NoWrapThrowers.ThrowAfterYieldAsync1);
+
+    [Fact]
+    public static void CatchBeforeYield_NoWrap_Async2()
+        => AssertNonExceptionWrapped(NoWrapThrowers.ThrowBeforeYieldAsync2);
+
+    [Fact]
+    public static void CatchBeforeYield_NoWrap_Async1()
+        => AssertNonExceptionWrapped(NoWrapThrowers.ThrowBeforeYieldAsync1);
+
+    private static void AssertNonExceptionWrapped(Func<Task> thrower)
+    {
+        object wrapped = ObserveNonException(thrower).GetAwaiter().GetResult();
+        Assert.Equal(ThrownObject, wrapped);
+    }
+
+    // Awaits the throwing method and returns the wrapped non-Exception object.
+    // The catch handler lives in this WrapNonExceptionThrows = true assembly, so a
+    // propagating non-Exception is caught as a RuntimeWrappedException. Returns null
+    // if nothing was thrown so the assertion above fails with a clear diff.
+    private static async Task<object> ObserveNonException(Func<Task> thrower)
+    {
+        try
+        {
+            await thrower();
+            return null;
+        }
+        catch (RuntimeWrappedException e)
+        {
+            return e.WrappedException;
+        }
+    }
+
+    // Runtime async (async2) throwing a non-Exception after suspending.
+    public static async Task ThrowAfterYieldAsync2()
+    {
+        await Task.Yield();
+        NonExceptionThrower.ThrowNonException();
+    }
+
+    // Compiler state machine (async1) throwing a non-Exception after suspending.
+    [RuntimeAsyncMethodGeneration(false)]
+    public static async Task ThrowAfterYieldAsync1()
+    {
+        await Task.Yield();
+        NonExceptionThrower.ThrowNonException();
+    }
+
+    // Runtime async (async2) throwing a non-Exception before suspending.
+    public static async Task ThrowBeforeYieldAsync2()
+    {
+        NonExceptionThrower.ThrowNonException();
+        await Task.Yield();
+    }
+
+    // Compiler state machine (async1) throwing a non-Exception before suspending.
+    [RuntimeAsyncMethodGeneration(false)]
+    public static async Task ThrowBeforeYieldAsync1()
+    {
+        NonExceptionThrower.ThrowNonException();
+        await Task.Yield();
+    }
+}

src/tests/async/runtime-wrapped-exception/runtime-wrapped-exception.csproj

@@ -0,0 +1,7 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+    <ProjectReference Include="NonExceptionThrower.ilproj" />
+    <ProjectReference Include="NoWrapThrowers.csproj" />
+  </ItemGroup>
+</Project>