Remove CS1998 warning entirely and remove dependent C# code fix providers #80144

Copilot · 2025-09-04T17:26:54Z

This PR removes the CS1998 (WRN_AsyncLacksAwaits) warning entirely from the C# compiler and removes all dependent C# infrastructure, based on the team decision that this warning is no longer beneficial.

Relates to test plan #75960.
Closes #77001.

Changes Made

Core compiler changes:

Removed CS1998 diagnostic emission from DefiniteAssignment.cs
Commented out WRN_AsyncLacksAwaits enum definition in ErrorCode.cs
Commented out references in ErrorFacts.cs and generated files
Deleted resource strings from CSharpResources.resx and all XLF translation files

Infrastructure cleanup:

Completely removed C# code fix providers (CSharpRemoveAsyncModifierCodeFixProvider and CSharpMakeMethodSynchronousCodeFixProvider) and their tests
Preserved abstract base classes and Visual Basic implementations for future VB consolidation
Updated telemetry descriptions to remove C# code fix provider references

Test updates:

Updated 32+ test files across the compiler test suite to remove CS1998 expectations
Removed C#-specific test classes for the deleted code fix providers

The warning infrastructure is now fully disabled for C# and won't be used again. Abstract base classes remain available for Visual Basic, which may continue to benefit from these diagnostics.

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Copilot · 2025-09-04T17:26:55Z

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Co-authored-by: 333fred <[email protected]>

333fred · 2025-09-04T17:53:52Z

@copilot please comment out the warning so we don't use it again in the future, and delete the resources associated with it.

Co-authored-by: 333fred <[email protected]>

Copilot · 2025-09-04T18:04:31Z

@copilot please comment out the warning so we don't use it again in the future, and delete the resources associated with it.

Done! I've commented out the CS1998 warning definition and deleted the associated resources:

Changes made (ca2c367):

Commented out WRN_AsyncLacksAwaits = 1998 in ErrorCode.cs to prevent future usage
Commented out references in ErrorFacts.cs and Generated files
Removed resource strings from CSharpResources.resx
Disabled both CSharpRemoveAsyncModifierCodeFixProvider and CSharpMakeMethodSynchronousCodeFixProvider (they can't function without the warning)
Updated scripting tests and disabled test classes that relied on CS1998

The warning infrastructure is now fully disabled and won't be used again in the future.

333fred · 2025-09-04T18:17:38Z

@copilot there are errors:

D:\a\_work\1\s\.packages\microsoft.dotnet.xlifftasks\10.0.0-beta.25427.2\build\Microsoft.DotNet.XliffTasks.targets(85,5): error : 'xlf\CSharpResources.cs.xlf' is out-of-date with 'CSharpResources.resx'. Run `msbuild /t:UpdateXlf` to update .xlf files or set UpdateXlfOnBuild=true to update them on every build, but note that it is strongly discouraged to set UpdateXlfOnBuild=true in official/CI build environments as they should not modify source code during the build. [D:\a\_work\1\s\src\Compilers\CSharp\Portable\Microsoft.CodeAnalysis.CSharp.csproj::TargetFramework=net9.0]
D:\a\_work\1\s\.packages\microsoft.dotnet.xlifftasks\10.0.0-beta.25427.2\build\Microsoft.DotNet.XliffTasks.targets(85,5): error : 'xlf\CSharpResources.cs.xlf' is out-of-date with 'CSharpResources.resx'. Run `msbuild /t:UpdateXlf` to update .xlf files or set UpdateXlfOnBuild=true to update them on every build, but note that it is strongly discouraged to set UpdateXlfOnBuild=true in official/CI build environments as they should not modify source code during the build. [D:\a\_work\1\s\src\Compilers\CSharp\Portable\Microsoft.CodeAnalysis.CSharp.csproj::TargetFramework=netstandard2.0]

333fred · 2025-09-04T18:24:20Z

@CyrusNajmabadi what do you want to do about CSharpRemoveAsyncModifierCodeFixProvider and CSharpMakeMethodSynchronousCodeFixProvider?

Co-authored-by: 333fred <[email protected]>

Copilot · 2025-09-04T18:25:00Z

@copilot there are errors:

D:\a\_work\1\s\.packages\microsoft.dotnet.xlifftasks\10.0.0-beta.25427.2\build\Microsoft.DotNet.XliffTasks.targets(85,5): error : 'xlf\CSharpResources.cs.xlf' is out-o...

Fixed! I've updated all XLF translation files to remove the WRN_AsyncLacksAwaits and WRN_AsyncLacksAwaits_Title entries that were causing the out-of-sync errors. The build errors should now be resolved (a2dde98).

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4zjvsblobprodcus390.vsblob.vsassets.io
- Triggering command: dotnet build src/Compilers/CSharp/Portable/Microsoft.CodeAnalysis.CSharp.csproj --no-restore (dns block)
6s7vsblobprodcus313.vsblob.vsassets.io
- Triggering command: dotnet build src/Compilers/CSharp/Portable/Microsoft.CodeAnalysis.CSharp.csproj --no-restore (dns block)
80zvsblobprodcus35.vsblob.vsassets.io
- Triggering command: dotnet build src/Compilers/CSharp/Portable/Microsoft.CodeAnalysis.CSharp.csproj --no-restore (dns block)
ckzvsblobprodcus347.vsblob.vsassets.io
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l49vsblobprodcus358.vsblob.vsassets.io
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m16vsblobprodcus374.vsblob.vsassets.io
- Triggering command: dotnet build src/Compilers/CSharp/Portable/Microsoft.CodeAnalysis.CSharp.csproj --no-restore (dns block)
pe3vsblobprodcus354.vsblob.vsassets.io
- Triggering command: dotnet build src/Compilers/CSharp/Portable/Microsoft.CodeAnalysis.CSharp.csproj --no-restore (dns block)
ytvvsblobprodcus310.vsblob.vsassets.io
- Triggering command: dotnet build src/Compilers/CSharp/Portable/Microsoft.CodeAnalysis.CSharp.csproj --no-restore (dns block)

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333fred · 2025-09-04T18:25:26Z

@copilot remove those unrelated changes in global.json and build.cmd

CyrusNajmabadi · 2025-09-04T18:26:47Z

@333fred are we removing the diagnostic entirely?

If so, we can just remove these fixers.

I assume we're doing the same for VB for consistency? Or are we intending divergence here?

333fred · 2025-09-04T18:27:33Z

@333fred are we removing the diagnostic entirely?

Yes.

I assume we're doing the same for VB for consistency? Or are we intending divergence here?

We'll need to clarify with folks. VB is not getting runtime async, so the benefits would be more murky.

Co-authored-by: 333fred <[email protected]>

Copilot · 2025-09-04T18:28:25Z

@copilot remove those unrelated changes in global.json and build.cmd

Removed the unrelated changes to global.json (newline) and Build.cmd (file permissions) in commit 800934c. The files are now restored to their original state.

src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncSpillTests.cs

src/Compilers/CSharp/Portable/Errors/ErrorCode.cs

src/Compilers/CSharp/Portable/FlowAnalysis/DefiniteAssignment.cs

jcouv

Done with review pass (commit 15)

jcouv

LGTM Thanks (commit 15)

* upstream/main: (206 commits) Remove bogus xlf tag (#80357) Fix missing type argument checks Add tests Use dotnet run file for generating compiler code (#80248) Only restore based on assets file changes if the actual content changed (#80341) make expressionbody analyzer use semanticspananalysis (#80339) [EnC] Use ignoreAssemblyKey: false to resolve symbol keys (#80342) Properly populate ExportedType metadata table in presence of extension block. (#80311) Propagate `params` to lambdas and local functions (#79880) Change 17.15 to VS 2026 preview. (#80325) Improve virtualproject support for older .NET SDKs (#80324) Update dependencies from https://github.com/dotnet/dotnet build 283666 (#80344) Update dependencies from https://github.com/dotnet/arcade build 20250917.6 (#80343) Simplifying Fix tests Fix tests Fix introduce variable placement in top level statements move to immutable types in signature help move to immutable types in signature help Fix check ...

333fred · 2025-09-18T20:20:30Z

@jjonescz any other comments?

This dependend on CS1998 which was removed: - dotnet/roslyn#77001 - dotnet/roslyn#80144

Initial plan

ba04869

Copilot AI assigned Copilot and 333fred Sep 4, 2025

Copilot started work on behalf of 333fred September 4, 2025 17:27 View session

Copilot AI and others added 3 commits September 4, 2025 17:35

Remove CS1998 warning emission and start updating tests

9216cd3

Co-authored-by: 333fred <[email protected]>

Update key async binding tests - remove CS1998 expectations

217edc4

Co-authored-by: 333fred <[email protected]>

Complete removal of CS1998 warning from all test files

4139e06

Co-authored-by: 333fred <[email protected]>

Copilot AI changed the title ~~[WIP] Consider not emitting CS1998 for interface implementations / method overrides~~ Remove CS1998 warning entirely for async methods without await operators Sep 4, 2025

Copilot AI requested a review from 333fred September 4, 2025 17:49

Copilot finished work on behalf of 333fred September 4, 2025 17:49

Copilot started work on behalf of 333fred September 4, 2025 17:54 View session

Comment out CS1998 warning definition and delete associated resources

ca2c367

Co-authored-by: 333fred <[email protected]>

dotnet-policy-service bot added the VSCode label Sep 4, 2025

Copilot AI changed the title ~~Remove CS1998 warning entirely for async methods without await operators~~ Remove CS1998 warning entirely and disable dependent infrastructure Sep 4, 2025

Copilot finished work on behalf of 333fred September 4, 2025 18:05

Copilot started work on behalf of 333fred September 4, 2025 18:17 View session

Update XLF files to remove WRN_AsyncLacksAwaits translations

a2dde98

Co-authored-by: 333fred <[email protected]>

Copilot finished work on behalf of 333fred September 4, 2025 18:25

Copilot started work on behalf of 333fred September 4, 2025 18:25 View session

Revert unrelated changes to global.json and Build.cmd

800934c

Co-authored-by: 333fred <[email protected]>

333fred added 2 commits September 12, 2025 09:58

Update CodeGenAsyncSpillTests after merge

305217c

Update baselines

31f0027

jjonescz reviewed Sep 13, 2025

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src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncSpillTests.cs Show resolved Hide resolved

jcouv self-assigned this Sep 16, 2025

jcouv mentioned this pull request Sep 16, 2025

Test Plan for Runtime Async #75960

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jcouv approved these changes Sep 18, 2025

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333fred added 2 commits September 18, 2025 10:53

Remove more superfluous warnings.

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jjonescz approved these changes Sep 19, 2025

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333fred enabled auto-merge (squash) September 19, 2025 16:12

333fred merged commit 84133cc into main Sep 19, 2025
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333fred deleted the copilot/fix-77001 branch September 19, 2025 18:08

dotnet-bot mentioned this pull request Sep 22, 2025

[Automated] PRs inserted in VS build main-11021.14 #80397

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akhera99 modified the milestones: Next, 18.0 P1, 18.0 P2 Sep 22, 2025

This was referenced Sep 25, 2025

[Automated] PRs inserted in VS build feature.debugger.main-11023.335 #80458

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[Automated] PRs inserted in VS build feature.Wix5-11030.241 #80529

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ltrzesniewski added a commit to ltrzesniewski/RazorBlade that referenced this pull request Nov 13, 2025

Remove the [ConditionalOnAsync] feature

15e9a86

This dependend on CS1998 which was removed: - dotnet/roslyn#77001 - dotnet/roslyn#80144

Remove CS1998 warning entirely and remove dependent C# code fix providers #80144

Remove CS1998 warning entirely and remove dependent C# code fix providers #80144

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