Optional Arguments example does not compile (in fsi at least)

[leifp]

The code example in the Optional Arguments section:

// A class with a method M, which takes in an optional integer argument.
type C() =
    _.M([<Optional; DefaultParameterValue(12)>] i) = i + 1

This has syntax errors (missing member I think), and does not compile (in the fsi repl). This version works:

open System.Runtime.InteropServices
// A class with a method M, which takes in an optional integer argument.
type C() =
    member _.M([<Optional; DefaultParameterValue(12)>] i) = i + 1

Environment:

F# Interactive version 12.0.4.0 for F# 6.0
$ dotnet --info
.NET SDK (reflecting any global.json):
 Version:   6.0.302
 Commit:    c857713418

Runtime Environment:
 OS Name:     ubuntu
 OS Version:  20.04
 OS Platform: Linux
 RID:         ubuntu.20.04-x64
 Base Path:   /usr/share/dotnet/sdk/6.0.302/

global.json file:
  Not found

Host:
  Version:      6.0.7
  Architecture: x64
  Commit:       0ec02c8c96

.NET SDKs installed:
  6.0.302 [/usr/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 6.0.7 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 6.0.7 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

Download .NET:
  https://aka.ms/dotnet-download

Learn about .NET Runtimes and SDKs:
  https://aka.ms/dotnet/runtimes-sdk-info

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Document Details

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• ID: 680c7c1b-10c0-0537-a52e-48214b55ca4c
• Version Independent ID: ec7268c9-a299-8a21-65c9-3da7dae8a45d
• Content: Methods - F#
• Content Source: docs/fsharp/language-reference/members/methods.md
• Product: dotnet-fsharp
• GitHub Login: @cartermp
• Microsoft Alias: dotnetcontent