Project templates are broken for .NET Framework

[Youssef1313]

Used Visual Studio

Visual Studio 2022

Are the latest Visual Studio updates installed?

Yes

Content of reqnroll.json (if present)

No response

Issue Description

https://github.com/reqnroll/Reqnroll.VisualStudio/blob/904c74a0be9a8175d83c2bb0bc752b982fddab50/Reqnroll.VisualStudio.ProjectTemplate/ProjectTemplate.csproj

The template doesn't compile for .NET Framework.

First, fails with:

Invalid 'nullable' value: 'Enable' for C# 7.3. Please use language version '8.0' or greater.

Then after addressing this, it fails with errors like:

obj\Debug\net48\TUnit.Core.SourceGenerator\TUnit.Core.SourceGenerator.Generators.AotModuleInitializerGenerator\AotModuleInitializer.g.cs 16

Steps to Reproduce

Create a project using .NET Framework.

Link to a project repository that reproduces the issue

No response

[gasparnagy]

Oh. Could you send a fix. We can set the language version to C# 12 (the default for .NET 8).

[Youssef1313]

Setting higher language version works, but isn't supported.

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/language-versioning

Using a C# language version newer than the version associated with your target TFM is unsupported.

So up to you how to fix/address this.