Compilation fails due to missing AttributeUsage targets

[dlidstrom]

Description

I originally filed this in the F# repo itself. It seems attribute usage has been improved in the compiler and Argu needs some updates. Here's the original issue reproduced:

I've just discovered that my code doesn't build with F# 8.0.300 and preview language version.

Repro steps

This is my project file:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <LangVersion>preview</LangVersion>
  </PropertyGroup>
  <ItemGroup>
    <Compile Include="Program.fs" />
  </ItemGroup>
  <ItemGroup>
    <PackageReference Include="Argu" Version="6.2.3" />
  </ItemGroup>
</Project>

and this is my Program.fs:

open Argu

type Arguments =
  | [<Mandatory>] Username of string
  interface IArgParserTemplate with
    member this.Usage =
      match this with
      | Username _ -> "Specifies the username"

printfn "Hello from F#"

Expected behavior

I expect this to compile cleanly.

Actual behavior

This fails to compile after I upgraded to 8.0.300 (from 8.0.204):

Program.fs(4,7): error FS0842: This attribute is not valid for use on this language element

Known workarounds

Work around is to revert back to latest language version.

Related information

.NET SDK:
 Version:           8.0.300
 Commit:            326f6e68b2
 Workload version:  8.0.300-manifests.bce0cb54
 MSBuild version:   17.10.4+10fbfbf2e

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  14.4
 OS Platform: Darwin
 RID:         osx-arm64
 Base Path:   /usr/local/share/dotnet/sdk/8.0.300/

.NET workloads installed:
There are no installed workloads to display.

Host:
  Version:      8.0.5
  Architecture: arm64
  Commit:       087e15321b

.NET SDKs installed:
  8.0.101 [/usr/local/share/dotnet/sdk]
  8.0.204 [/usr/local/share/dotnet/sdk]
  8.0.300 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 8.0.1 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.4 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.5 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 7.0.15 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.1 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.4 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.5 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
  None

Environment variables:
  Not set

global.json file:
  Not found

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