Error updating project that uses codegen to .NET8

[MrYossu]

I have a project that is currently targeting .NET7, and uses the [Union] attribute.

I tried changing the .NET version to 8 (and updating all Nuget packages to the latest), but when I try to build, it fails with the following error...

Error MSB3073: The command "dotnet codegen "@obj\Debug\net8.0\MyProject.csproj.dotnet-codegen.rsp"" exited with code 3. (85, 6)

My project file includes the following section...

  <ItemGroup>
    <PackageReference Include="LanguageExt.Core" Version="4.4.9" />
    <PackageReference Include="LanguageExt.CodeGen" Version="4.4.8" PrivateAssets="all" />
    <PackageReference Include="CodeGeneration.Roslyn.BuildTime" Version="0.6.1" PrivateAssets="all" />
    <DotNetCliToolReference Include="dotnet-codegen" Version="0.6.1" />
    <PackageReference Include="Microsoft.AspNetCore.Components.Web" Version="8.0.10" />
  </ItemGroup>

Anyone any idea how I fix this?

Please let me know if there is any more info you need. Thanks

[aloslider]

Using a test project I don't have such error:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="LanguageExt.CodeGen" Version="4.4.8" PrivateAssets="all" />
    <PackageReference Include="LanguageExt.Core" Version="4.4.9" />
	<PackageReference Include="CodeGeneration.Roslyn.BuildTime" Version="0.6.1" PrivateAssets="all" />
	<DotNetCliToolReference Include="dotnet-codegen" Version="0.6.1" />
  </ItemGroup>

</Project>

using LanguageExt;
using LanguageExt.ClassInstances;
using LanguageExt.TypeClasses;

Shape<TInt, int> s = Shape.Circle<TInt, int>(5);
Console.WriteLine(s.ToString());

[Union]
public abstract partial class Shape<NumA, A> where NumA : struct, Num<A>
{
    public abstract Shape<NumA, A> Rectangle(A width, A length);
    public abstract Shape<NumA, A> Circle(A radius);
    public abstract Shape<NumA, A> Prism(A width, A height);
}

I've added PrivateAssets="all" to LanguageExt.CodeGen line, but it also builds without it.

I remember I had some error with codegen as well long time ago, and the answer was in some issue thread. The solutions was something with dotnet-codegen properties

[MrYossu]

Using a test project I don't have such error:

Hmm, your settings are the same as mine. I wonder why I get the error then. Causing me great problems as I have some code that urgently needs this upgrade.

Any ideas what else might be the cause?

I remember I had some error with codegen as well long time ago, and the answer was in some issue thread. The solutions was something with dotnet-codegen properties

I vaguely remember having some issues with it when I first set up this project, but no idea what they were. I followed someone's advice to add the references to CodeGeneration.Roslyn.BuildTime and dotnet-codegen exactly as-is, and it worked.

Thanks for the reply. Any further help you can give would be appreciated, as I'm stumped.

[louthy]

I've stopped supporting the CodeGen library because the CodeGeneration.Roslyn.BuildTime library is so finicky and seems especially problematic depending on the .NET SDKs you have installed.

If you want to do unions, I advise using records:

public abstract record Maybe<A>
{
    private Maybe() { }
    public sealed record Just(A value) : Maybe<A>;
    public sealed record Nothing : Maybe<A>;
}

public static class Maybe
{
    public static Maybe<A> Just<A>(A value) => new Maybe<A>.Just(value);
    public static Maybe<A> Nothing<A>() => new Maybe<A>.Nothing();
}

It doesn't quite have all of the features of the lang-ext unions, but it gets you 90% of the way without too much typing.

[MrYossu]

@louthy Oh, that's worth knowing. I'll have a go with records and see if anything breaks. I'm not doing anything particularly clever, so I doubt I'll hit any of the missing 90% 😎

Thanks for a fantastic library.

[louthy]

If you're already using [Union] then you may want to create your record based unions like this:

public abstract record Maybe<A>;
public sealed record Just(A value) : Maybe<A>;
public sealed record Nothing : Maybe<A>;

public static class Maybe
{
    public static Maybe<A> Just<A>(A value) => new Just<A>(value);
    public static Maybe<A> Nothing<A>() => new Nothing<A>();
}

Because the case-types are all top-level with [Union].

[MrYossu]

In case it helps anyone, I found this old issue in which it was pointed out that you need version 2.1.818 exactly of the SDK. Not sure if I've installed that version since I got my latest PC, but repairing the installation (which is what the downloader claimed it was doing) fixed the issue.

SDK can be downloaded here

@louthy Thanks again, when I have more time I'll look at dropping the code gen altogether and using records as you suggested.