VS2019 crashes when an F# source contains this string: let xxx x y = (# "divvvv" x y : float #)

[Arshia001]

My installation of Visual Studio 2019 (version 16.1.5) crashed after I typed in this code and refuses to open the project again:

let xxx x y = (# "divvvv" x y : float #)

Repro steps

1. Open an F# project in VS2019
2. Type in the above code
3. Mouse over the code.

Expected behavior

It should probably show an error that reads "Don't mess with stuff you don't understand, kid."

Actual behavior

Crashes completely.

Known workarounds

Open the file in another editor, remove that code.

• Operating system Windows 10
• .NET Runtime kind dotnet core 3.0 preview 6
• Editing Tools VS 2019

[cartermp]

Repro'd. This is critical to fix. cc @TIHan @brettfo @KevinRansom

[KevinRansom]

Is this a regression?

[cartermp]

I'm assuming VS didn't hard crash whenever IL literals were specified in source at some point, yes.

[TIHan]

Yea, this should not take down VS.

[TIHan]

It seems to crash when the IL in the string is invalid.

[TIHan]

So, I don't think this is a regression, or at least a recent one.

Basically, the parser for the IL string will throw an exception by failwith "parse error" which will cause it to not recover and will re-raise that exception in which case, nothing handles it and takes down VS.

[TIHan]

Closing as we merged the fix.