FSI sometimes gets confused by tabs: "Unexpected symbol # in interaction. Expected incomplete structured construct at or before this point"

[MaxWilson]

FSI sometimes gets confused by tabs.

Repro steps

1. Open Microsoft (R) F# Interactive version 12.5.0.0 for F# 7.0

2. Type in the following program

    let three() =
        3

3. Highlight the second line (" 3") and Send to Interactive.

Expected behavior

FSI should evaluate and return 3.

Actual behavior

Error.

    System.IO.File.WriteAllText(@"C:\Users\wilso\AppData\Local\Temp\tmpE9F5.tmp.pid", string (System.Diagnostics.Process.GetCurrentProcess().Id));;
  ^

    stdin(1,1): error FS0010: Unexpected symbol # in interaction. Expected incomplete structured construct at or before this point, ';', ';;' or other token.

Known workarounds

Un-indent code before sending it to F# interactive.

let three() =
3

Related information

• Operating system: Windows
• .NET Runtime kind: Net Core 7.0
• Editing Tools: VS 2022 17.6.0 Preview 1.0

[PatrickSimpsonGFCMSU]

I'm experiencing this same issue with VS 2022 Version 17.5.1 and 17.5.2 as well.

The code inside of methods that used to be able to be sent and executed that has any indentation now reports the following error:
System.IO.File.WriteAllText(@"C:\Users\psimp\AppData\Local\Temp\tmp4367.tmp.pid", string (System.Diagnostics.Process.GetCurrentProcess().Id));;
^

stdin(1,1): error FS0010: Unexpected symbol # in interaction. Expected incomplete structured construct at or before this point, ';', ';;' or other token.

Note It seems the additional code that is sent by VS to fsi that does not appear in the interactive console has a bug in it. I believe it might be related to the System.IO.File call since it shows an indent in front of the expression.

[PatrickSimpsonGFCMSU]

This is also happening on:
Microsoft Visual Studio Community 2022 (64-bit) - Preview
Version 17.6.0 Preview 2.0

as well.

I was not able to revert back further than 17.5.1 but I know it was working 8 weeks ago or so.

[vzarytovskii]

Yeah, I still see it on latest main cc @KevinRansom