ChangeSignature isn't aware of nullability

[jcouv]

1. The popup dialog doesn't display nullability annotations (?).
2. Changing the order of parameters on a signature involving nullability causes a crash.

FYI @dpoeschl

[CyrusNajmabadi]

That's concerning. What's the crash? Does that indicate some change in behavior in existing APIs that is not compatible with previous contracts?

[jcouv]

The crash shows an InvalidOperationException with WaitAndGetResult cannot be called from a thread pool thread.. That doesn't look related to nullability.
This is on 15.9 preview 1.

@dpoeschl Does this look familiar by any chance?

   at Roslyn.Utilities.TaskExtensions.WaitAndGetResult[T](Task`1 task, CancellationToken cancellationToken) in C:\repos\roslyn\src\Workspaces\Core\Portable\Utilities\TaskExtensions.cs:line 75
   at Microsoft.CodeAnalysis.ChangeSignature.AbstractChangeSignatureService.TryCreateUpdatedSolution(ChangeSignatureAnalyzedContext context, ChangeSignatureOptionsResult options, CancellationToken cancellationToken, Solution& updatedSolution) in C:\repos\roslyn\src\Features\Core\Portable\ChangeSignature\AbstractChangeSignatureService.cs:line 209
   at Microsoft.CodeAnalysis.ChangeSignature.AbstractChangeSignatureService.ChangeSignatureWithContext(ChangeSignatureAnalyzedContext context, ChangeSignatureOptionsResult options, CancellationToken cancellationToken) in C:\repos\roslyn\src\Features\Core\Portable\ChangeSignature\AbstractChangeSignatureService.cs:line 160
   at Microsoft.CodeAnalysis.ChangeSignature.ChangeSignatureCodeAction.ComputeOperationsAsync(Object options, CancellationToken cancellationToken) in C:\repos\roslyn\src\Features\Core\Portable\ChangeSignature\ChangeSignatureCodeAction.cs:line 33
   at Microsoft.CodeAnalysis.CodeActions.CodeActionWithOptions.<GetOperationsAsync>d__1.MoveNext() in C:\repos\roslyn\src\Workspaces\Core\Portable\CodeActions\CodeActionWithOptions.cs:line 37
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Roslyn.Utilities.TaskExtensions.WaitAndGetResult_CanCallOnBackground[T](Task`1 task, CancellationToken cancellationToken) in C:\repos\roslyn\src\Workspaces\Core\Portable\Utilities\TaskExtensions.cs:line 87
   at Roslyn.Utilities.TaskExtensions.WaitAndGetResult[T](Task`1 task, CancellationToken cancellationToken) in C:\repos\roslyn\src\Workspaces\Core\Portable\Utilities\TaskExtensions.cs:line 74
   at Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedAction.InvokeWorker(Func`1 getFromDocument, IProgressTracker progressTracker, CancellationToken cancellationToken) in C:\repos\roslyn\src\EditorFeatures\Core.Wpf\Suggestions\SuggestedActions\SuggestedAction.cs:line 153
   at Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedAction.<>c__DisplayClass18_0.<InvokeCore>b__0() in C:\repos\roslyn\src\EditorFeatures\Core.Wpf\Suggestions\SuggestedActions\SuggestedAction.cs:line 138
   at Microsoft.CodeAnalysis.Extensions.IExtensionManagerExtensions.PerformAction(IExtensionManager extensionManager, Object extension, Action action) in C:\repos\roslyn\src\Workspaces\Core\Portable\ExtensionManager\IExtensionManagerExtensions.cs:line 23

[dpoeschl]

Yeah, seems unrelated. Probably need to do something like #29484 here as well

[dpoeschl]

Should have emphasized the "seems". It's reproing in this scenario for you?

[jcouv]

Yes, I repro'ed this on two machines (work and home). Both with 15.9.
In one case I used the async-streams branch as-is, in the other case I used a merge of dev16.0.x into the async-streams branch (this is where the stacktrace was taken from).
I will try again this afternoon with plain dev16.0.x for comparison.

[jasonmalinowski]

Confirmed that the crash is badness in this code doing async-over-sync-over-async and isn't related to nullable -- if you remove the assert it works just fine. That's also asserting in literally any application, so it's not new.