Use prototype Roslyn compiler for runtime-async #115531

agocke · 2025-05-13T21:32:53Z

This pulls in the prototype Roslyn compiler from the Roslyn runtime-async prototype branch. Currently the feature in the runtime is gated on a feature flag, so the tests are disabled.

To run the tests locally, do the following:

Uncomment add_compile_definitions(FEATURE_RUNTIME_ASYNC) - to enable the feature in the product.
Remove DisableProjectBuild from src\tests\async\Directory.Build.targets

Copilot

Pull Request Overview

This PR updates the codebase to use the new prototype Roslyn compiler's runtime-async implementation by replacing the deprecated "async2" keyword with the standard "async" keyword and adding runtime async method generation attributes where needed.

Replaces "async2" with "async" across multiple test files and implementations.
Adds [RuntimeAsyncMethodGeneration(false)] attributes to selected methods to control async state machine generation.
Updates project configuration files (Directory.Build.props, NuGet.config) and runtime feature definitions to support the new async feature.

Reviewed Changes

Copilot reviewed 34 out of 34 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/tests/async/pgo/pgo.cs	Replaced async2 with async in entry point and aggregate methods.
src/tests/async/override/override.cs	Updated method signatures in base and derived classes to use async; added generation attributes.
src/tests/async/objects-captured/objects-captured.cs	Updated async method signatures.
src/tests/async/object/object.cs	Replaced async2 with async in asynchronous entry and object methods.
src/tests/async/mincallcost-microbench/mincallcost-microbench.cs	Multiple async2 methods replaced with async and attributes added where needed.
src/tests/async/implement/implement.cs	Simplified interface and implementation method signatures to use async.
src/tests/async/gc-roots-scan/gc-roots-scan.cs	Replaced async2 with async in recursive methods.
src/tests/async/fibonacci-without-yields/fibonacci-without-yields.cs	Updated async method signatures in Fibonacci test.
src/tests/async/fibonacci-with-yields_struct_return/fibonacci-with-yields_struct_return.cs	Updated async method signatures and return types.
src/tests/async/fibonacci-with-yields/fibonacci-with-yields.cs	Replaced async2 with async in test and Fibonacci methods.
src/tests/async/eh-microbench/eh-microbench.cs	Updated multiple async2 method signatures to async and added attributes to benchmarking methods.
src/tests/async/cse-array-index-byref/cse-array-index-byref.cs	Updated async method signature for hoisted byref test.
src/tests/async/collectible-alc/collectible-alc.cs	Replaced async2 with async in async entry points and helper methods.
src/tests/async/awaitingnotasync/awaitingnotasync.cs	Updated async method signature for the async entry point.
src/tests/async/RuntimeAsyncMethodGenerationAttribute.cs	Added the attribute definition for runtime async generation.
src/tests/async/Directory.Build.props	Added the features flag for runtime-async and included the attribute file.
src/tests/Directory.Build.props	Overrode the compiler version to one that supports async changes.
src/libraries/System.Runtime/ref/System.Runtime.cs	Updated runtime feature to include Async.
src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeFeature.cs	Updated runtime feature support for Async with proper attribute handling.
NuGet.config	Added a package source for prototype Roslyn compiler testing.

src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeFeature.cs

src/tests/Directory.Build.props

dotnet-policy-service · 2025-05-13T23:15:11Z

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agocke · 2025-05-13T23:15:24Z

@VSadov any info on what I need to set to run tests locally?

VSadov · 2025-05-14T00:25:27Z

@VSadov any info on what I need to set to run tests locally?

In #115499 (comment)
I used these steps:

* patch the toolset compiler - basically do `buildroslynnugets.bat` per runtimelab instructions and copy `tasks` 
from the `Microsoft.Net.Compilers.Toolset.5.0.0-async-16.nupkg` (rename to .zip and open) 
to `C:\Users\<user>\.nuget\packages\microsoft.net.compilers.toolset\5.0.0-1.25220.1`, or whatever version is in use by the build.
* uncomment `add_compile_definitions(FEATURE_RUNTIME_ASYNC)`  - to enable the feature in the product.
* delete `src\tests\async\Directory.Build.targets` - to unblock async tests from building.

Then build/run tests as usual. Tests under `async` should build, run and pass.

I think the part about patching the toolset compiler does not apply here. So it is really:

uncomment add_compile_definitions(FEATURE_RUNTIME_ASYNC) - to enable the feature in the product.
delete src\tests\async\Directory.Build.targets - to unblock async tests from building.

Then do regular:

build clr+libs -rc checked -lc release
src\tests\build.bat checked
src\tests\run.bat checked

VSadov · 2025-05-14T00:34:48Z

from the failures it looks like it has built the tests successfully 👍, but runtime did not want to load them, because the feature is not enabled in the runtime - the step:
uncomment add_compile_definitions(FEATURE_RUNTIME_ASYNC) - to enable the feature in the product.

filipnavara · 2025-05-14T02:16:44Z

src/tests/Directory.Build.props

+  <PropertyGroup>
+    <!-- Override the compiler version with a private build that supports runtime-async -->
+    <MicrosoftNetCompilersToolsetVersion>5.0.0-1.25259.6</MicrosoftNetCompilersToolsetVersion>
+  </PropertyGroup>


Is there a reason to have this in src/tests/Directory.Build.props instead of src/tests/async/Directory.Build.props?

I don't think this worked when I tried it earlier. Let me try again.

It needs to be here because we don't restore individual test projects (there's too many). Instead we restore the test_dependencies projects and point the individual test projects at those restore results.

One day I'll get this cleaned up I hope.

agocke · 2025-05-14T02:18:23Z

from the failures it looks like it has built the tests successfully 👍, but runtime did not want to load them, because the feature is not enabled in the runtime - the step: uncomment add_compile_definitions(FEATURE_RUNTIME_ASYNC) - to enable the feature in the product.

Yup, this worked, thanks. For now I've kept the tests disabled in PR since we don't want to enable the ifdef. But it looks like everything passes now except the EH test.

agocke · 2025-05-14T17:57:44Z

I believe this is all up-to-date now. This PR still keeps all the tests disabled since I'm not building the runtime with the if-def.

src/tests/async/RuntimeAsyncMethodGenerationAttribute.cs

src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeFeature.cs

VSadov · 2025-05-15T00:58:30Z

src/tests/async/fibonacci-with-yields/fibonacci-with-yields.csproj

@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <Optimize>True</Optimize>
+    <Features>$(Features);runtime-async</Features>


Why some .csproj need runtime-async=on and not others?

jakobbotsch · 2025-05-15T09:34:54Z

it looks like everything passes now except the EH test

Any idea why this breaks the EH test?

VSadov · 2025-05-15T13:04:29Z

it looks like everything passes now except the EH test

Any idea why this breaks the EH test?

There is a known issue with C# compiler.

jakobbotsch · 2025-05-15T15:07:17Z

src/tests/async/implement/implement.cs

@@ -24,7 +25,8 @@ public async Task<int> M1()

    class Derived1a : IBase1
    {
-        public async2 Task<int> M1()
+        [MethodImpl(MethodImplOptions.Async)]


Are these necessary?

I think these were a workaround for the change in the numerical value for the async methodimpl, that C# compiler was not updated for.
I thought that has been fixed and the workaround is no longer necessary. Maybe this one was just missed when others were reverted.

Yup, just missed during cleanup

jakobbotsch · 2025-05-16T08:26:51Z

I pushed a change that also updates the test I added in #115605 to the new style.

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This was referenced May 14, 2025

[wasm][AOT] emcc : error - received SIGKILL (-9) #89402

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SIGKILL System.Runtime.Serialization.Formatters.Tests #114287

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Test using Roslyn prototype compiler

03becbe

agocke force-pushed the use-prototype-compiler branch from 62739c5 to 03becbe Compare May 14, 2025 02:09

Fix mention of async2

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This was referenced May 14, 2025

System.Runtime.Tests.WorkItemExecution "crash" on tvOS #106319

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Test System.Runtime.InteropServices.JavaScript.Tests.TimerTests.TestTimers failing with "setCounter: actual 12 expected 13" #115346

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jkotas reviewed May 14, 2025

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src/tests/async/RuntimeAsyncMethodGenerationAttribute.cs Show resolved Hide resolved

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agocke mentioned this pull request May 14, 2025

Use prototype roslyn compiler dotnet/runtimelab#3062

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Respond to PR comments

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build-analysis bot mentioned this pull request May 15, 2025

Test failure: baseservices/exceptions/stackoverflow/stackoverflowtester/stackoverflowtester.cmd #110173

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Missed items during cleanup

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System.Net.Quic.Tests.MsQuicTests.WriteTests failed with "System.Net.Quic.QuicException : The connection timed out from inactivity." #105177

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jakobbotsch added 2 commits May 16, 2025 10:15

Merge branch 'main' of github.com:dotnet/runtime into pr-115531

5bc0851

Update strength-reduction test to new style

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CI flakiness: mono interpreter build getting killed #114123

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agocke merged commit 0f0b4b4 into dotnet:main May 16, 2025
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Use prototype Roslyn compiler for runtime-async #115531

Use prototype Roslyn compiler for runtime-async #115531

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