Internal error when typing in VS

[kerams]

Repro steps

type D =
    | A
    | B

    member

Expected behavior

No issues.

Actual behavior

internal error: GetInstanceMemberThisVariable: instance member did not have expected internal form
System.Exception: GetInstanceMemberThisVariable: instance member did not have expected internal form   at
FSharp.Compiler.CheckExpressions.firstArg@3929.Invoke(Expr e) in C:\code\fsharp\src\Compiler\Checking\CheckExpressions.fs:line 3933    at
FSharp.Compiler.CheckExpressions.TcLetrecBinding(TcFileState cenv, TcEnv envRec, Range scopem, FSharpList`1 extraGeneralizableTypars, FSharpOption`1 reqdThisValTyOpt, TcEnv envNonRec, FSharpList`1 generalizedRecBinds, FSharpList`1 preGeneralizationRecBinds, UnscopedTyparEnv tpenv, FSharpMap`2 uncheckedRecBindsTable, PreCheckingRecursiveBinding rbind) in C:\code\fsharp\src\Compiler\Checking\CheckExpressions.fs:line 11665
....

Related information

Provide any related information (optional):

• main at f9e66b4

[kerams]

Another one, just

module

internal error: empty list Parameter name: l
System.ArgumentException: empty list Parameter name: l    at
Internal.Utilities.Library.List.loop@426-17T.Invoke(FSharpList`1 acc, FSharpList`1 l) in C:\code\fsharp\src\Compiler\Utilities\illib.fs:line 430    at
FSharp.Compiler.CheckDeclarations.TcModuleOrNamespaceElementNonMutRec@4865-1.Invoke(CancellationToken ct) in C:\code\fsharp\src\Compiler\Checking\CheckDeclarations.fs:line 5027

Likely related to recovery changes.

[vzarytovskii]

cc @auduchinok

I think we haven't inserted those yet.

[auduchinok]

Likely related to recovery changes.

cc @auduchinok

I think we haven't inserted those yet.

Yes, it's likely the cause. The type checker will require small adjustments for the cases like these, like it was done here, and I was going to do a throughout testing for all these unfinished constructs after the initial parsing work is mostly done. I really hope that I'm very close to that. 🙂

Now I think I should look there a bit sooner, so I'll try to look into it tomorrow.

[kerams]

I'll keep posting what I run into

``

`

[auduchinok]

@kerams What exceptions do you run into with the last examples? They don't fail for me in #15458.

[kerams]

[auduchinok]

I see, it's not a type checker problem here. Thanks!