FS0073: internal error: ImportILTypeRef: unexpected local scope using System.Collections.Immutable

[marklam]

Calling ImmutableQueue.Dequeue or IImmutableStack.Pop causes internal compiler errors

Repro steps

1. Clone https://github.com/fsprojects/FSharp.Collections.Immutable
2. dotnet build

Expected behavior

Compilation succeeds

Actual behavior

FSharp.Collections.Immutable\src\FSharp.Collections.Immutable\stack.fs(33,9): error FS0073: internal error: ImportILTypeRef: unexpected local scope
FSharp.Collections.Immutable\src\FSharp.Collections.Immutable\stack.fs(42,33): error FS0073: internal error: ImportILTypeRef: unexpected local scope
FSharp.Collections.Immutable\src\FSharp.Collections.Immutable\queue.fs(28,47): error FS0073: internal error: ImportILTypeRef: unexpected local scope

Known workarounds

As per @vzarytovskii 's comment below, Adding <LangVersion>7.0</LangVersion> to a PropertyGroup in the fsproj allows the compilation to succeed.

Related information

• Operating system : Windows 10

c:\git>dotnet --list-sdks
6.0.417 [C:\Program Files\dotnet\sdk]
8.0.100 [C:\Program Files\dotnet\sdk]

[vzarytovskii]

builds with 7.0.404, so something recent

[vzarytovskii]

Also builds with <LangVersion>7.0</LangVersion>, so, something from 8.0 featureset.

[marklam]

@vzarytovskii: Edited the issue to add that workaround, thanks.

[auduchinok]

This may have also been fixed by #16390.