F# 9, .net 9 type extension of IEnumerable<'T>

[wallymathieu]

Please provide a succinct description of the issue.

Repro steps

See documentation for optional-type-extensions:

Create a file such as Extensions.fsx:

module Extensions=
    open System.Collections.Generic

    type IEnumerable<'T> with
        /// Repeat each element of the sequence n times
        member xs.RepeatElements(n: int) =
            seq {
                for x in xs do
                    for _ in 1 .. n -> x
            }

Expected behavior

That the example from the documentation compiles

Actual behavior

Compilation error :

One or more of the declared type parameters for this type extension have a missing or wrong type constraint not matching the original type constraints on 'IEnumerable<_>'F# Compiler[957](https://docs.microsoft.com/en-us/dotnet/fsharp/language-reference/compiler-messages/fs0957)

Known workarounds

• Use previous version of .net
• Create a C# extension method

Related information

Provide any related information (optional):

• Operating system : Windows 11, Mac OS X
• .NET Runtime kind: .NET Core 9 9.0.101, 9.0.102
• Editing Tools (Visual Studio Code)

[brianrourkeboll]

I think this is the same as #18001.

[wallymathieu]

Yes, it looks like the same issue