VS crashes if you rename an F# symbol where it is at the top of a file or unsaved file

[cartermp]

Using 15.6.4 and latest master installed into it, attempt to rename Record in the following code:

type Record = { IntVal: int; StringVal: string }

[<AbstractClass>]
type AbstractFoo<'T>() =
    abstract member Foo: 'T -> 'T

type C() =
    inherit AbstractFoo<Record>()
    override __.Foo(r) = { r with IntVal = 12 }

After typing the first character, the inline rename service will crash, followed by VS crashing.

This is the stack trace in the activity log:

System.NullReferenceException: Object reference not set to an instance of an object. at 
Microsoft.CodeAnalysis.Editor.Implementation.InlineRename.InlineRenameSession.CommitCore(IWaitContext waitContext, Boolean previewChanges) at 
Microsoft.CodeAnalysis.Editor.Implementation.InlineRename.InlineRenameSession.<>c__DisplayClass71_0.<Commit>b__0(IWaitContext waitContext) at 
Microsoft.VisualStudio.LanguageServices.Implementation.Utilities.VisualStudioWaitIndicator.Wait(String title, String message, Boolean allowCancel, Boolean showProgress, Action`1 action) at 
Microsoft.CodeAnalysis.Editor.Implementation.InlineRename.InlineRenameSession.Commit(Boolean previewChanges) at 
Microsoft.CodeAnalysis.Editor.Implementation.InlineRename.RenameCommandHandler.CommitIfActive(EditorCommandArgs args) at 
Microsoft.CodeAnalysis.Editor.Implementation.InlineRename.RenameCommandHandler.CommitIfActiveAndCallNextHandler(EditorCommandArgs args, Action nextHandler) at 
Microsoft.CodeAnalysis.Editor.Implementation.InlineRename.RenameCommandHandler.HandlePossibleTypingCommand(EditorCommandArgs args, Action nextHandler, Action`1 actionIfInsideActiveSpan) at 
Microsoft.CodeAnalysis.Editor.Implementation.InlineRename.RenameCommandHandler.ExecuteCommand(TypeCharCommandArgs args, Action nextHandler, CommandExecutionContext context) at 
Microsoft.VisualStudio.Commanding.CommandHandlerExtensions.ExecuteCommand[T](ICommandHandler commandHandler, T args, Action nextCommandHandler, CommandExecutionContext executionContext) at 
Microsoft.VisualStudio.UI.Text.Commanding.Implementation.EditorCommandHandlerService.<>c__DisplayClass14_1`1.<Execute>b__1() at 
Microsoft.VisualStudio.Text.Utilities.GuardedOperations.CallExtensionPoint(Object errorSource, Action call) --- End of stack trace from previous location where exception was thrown --- at 
Microsoft.VisualStudio.Telemetry.WindowsErrorReporting.WatsonReport.GetClrWatsonExceptionInfo(Exception exceptionObject)

Currently this makes it impossible to test out a fix for #4231 😢

[abelbraaksma]

Some observations, in case it helps:

This is not caused by the latest master, at the very least the bug has been out for a little while longer. I haven't updated to latest master, but I can repro in an instance of VS2017 15.6.4 and VS2017 15.7.0 Preview 2 (which means, I believe, that Preview 2 is "installed into" 15.6.4. as well wrt F# services and compiler).

I also noted that the lookup-screen says "will replace 0 references in 0 files", perhaps that is a hint?

Even more worrying, when I put back focus on the editor while the rename-box is still visible top-right, I get this ("An exception has been encountered"):

And, still more surprising, even when I don't apply the renaming (hit cancel or the X in top-right of rename window), it still crashes!

[dsyme]

@cartermp @abelbraaksma I don't get a crash, but I do get a double-rename of he generic parameter:

e.g.

type Record = { IntVal: int; StringVal: string }
...
    inherit AbstractFoo<Record>()

becomes

type AA = { IntVal: int; StringVal: string }
...
    inherit AbstractFoo<AAAA>()

note the AAAA

[dsyme]

I fixed the double renaming in #4810

[cartermp]

@dsyme Did you test this with just 15.6.x, or with 15.6.x and a master VSIX built in, or 15.7? The crash occured for me in the latter two setups, but not "normal" 15.6.x.

[dsyme]

Just 15.6.x plus F5 launch of Visualfsharp. sln

[buybackoff]

Probably the same issue, I see an error right after I press F2:

Rename doesn't happen, but the 'rename apply' window is always open when the editor windows is in focus:

Same place and machine config (VS 15.7) as in #4209 with today's (May 15) nightly build.

[chillitom]

Tested out the original example a couple of times on 15.7.1 and once got the "An exception has been encountered" message and once got the double renaming (now fixed in nightlies).

[chillitom]

The double rename also occurs if I rename AbstractFoo. I've repeated the test roughly 25 times and haven't been able to recreate the exception. Perhaps requires a solution that has been open/churning for a while to trigger the conditions for this crash.

[chillitom]

Error from ActivityLog.xml

System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.CodeAnalysis.Editor.Implementation.InlineRename.InlineRenameSession.CommitCore(IWaitContext waitContext, Boolean previewChanges)
   at Microsoft.CodeAnalysis.Editor.Implementation.InlineRename.InlineRenameSession.<>c__DisplayClass71_0.<Commit>b__0(IWaitContext waitContext)
   at Microsoft.VisualStudio.LanguageServices.Implementation.Utilities.VisualStudioWaitIndicator.Wait(String title, String message, Boolean allowCancel, Boolean showProgress, Action`1 action)
   at Microsoft.CodeAnalysis.Editor.Implementation.InlineRename.InlineRenameSession.Commit(Boolean previewChanges)
   at Microsoft.CodeAnalysis.Editor.Implementation.InlineRename.RenameCommandHandler.ExecuteCommand(ReturnKeyCommandArgs args, CommandExecutionContext context)
   at Microsoft.VisualStudio.Commanding.CommandHandlerExtensions.ExecuteCommand[T](ICommandHandler commandHandler, T args, Action nextCommandHandler, CommandExecutionContext executionContext)
   at Microsoft.VisualStudio.UI.Text.Commanding.Implementation.EditorCommandHandlerService.<>c__DisplayClass14_1`1.<Execute>b__1()
   at Microsoft.VisualStudio.Text.Utilities.GuardedOperations.CallExtensionPoint(Object errorSource, Action call)
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.VisualStudio.Telemetry.WindowsErrorReporting.WatsonReport.GetClrWatsonExceptionInfo(Exception exceptionObject)

[cartermp]

@chillitom It sounds like a race condition based on what you're saying. I haven't tried to repro this on 15.7 yet.