Dictionary value type parameter generalisation leads to unassignable types

[Draeggiar]

Describe the bug
After update to version 3.4.0 from 3.3.0 Mapperly started to generate non-compilable code.
In this example i have two classes with identical property MyDictionary. The problem lays in signature of generated MapToIDictionary method. It used to accept List as dictionary value parameter but it changed to IReadonlyCollection.

Declaration code

public class A
{
    public int Value { get; set; }
}

public class B
{
    public int Value { get; set; }
}

public class ModelA
{
    public IDictionary<int, List<A>>? MyDictionary { get; set; }
}

public class ModelB
{
    public IDictionary<int, List<B>>? MyDictionary { get; set; }
}

[Mapper]
public partial class MyMapper
{
    public partial ModelB MapA(ModelA source);
}

Actual generated code

    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "3.4.0.0")]
    private global::System.Collections.Generic.Dictionary<int, global::System.Collections.Generic.List<global::B>> MapToDictionary(global::System.Collections.Generic.IDictionary<int, global::System.Collections.Generic.IReadOnlyCollection<global::A>> source)
    {
        var target = new global::System.Collections.Generic.Dictionary<int, global::System.Collections.Generic.List<global::B>>(source.Count);
        foreach (var item in source)
        {
            target[item.Key] = MapToList(item.Value);
        }
        return target;
    }

Expected generated code (This was generated in version 3.3.)

    private global::System.Collections.Generic.IDictionary<int, global::System.Collections.Generic.List<global::B>> MapToIDictionary(global::System.Collections.Generic.IDictionary<int, global::System.Collections.Generic.List<global::A>> source)
    {
        var target = new global::System.Collections.Generic.Dictionary<int, global::System.Collections.Generic.List<global::B>>(source.Count);
        foreach (var item in source)
        {
            target[item.Key] = MapToList(item.Value);
        }
        return target;
    }

Environment (please complete the following information):

• Mapperly Version: 3.4.0
• .NET Version: .NET 8.0.100
• Target Framework: .net8.0
• Compiler Version: 4.8.0-3.23524.11 (f43cd10b)
• C# Language Version: 12.0
• IDE: Rider 2023.3.3
• OS: Windows 11

[latonz]

Thanks for reporting this, it definitely looks like a bug! We should never generalise the type arguments.

[github-actions]

🎉 This issue has been resolved in version 3.5.0-next.1 🎉

The release is available on:

• GitHub release
• v3.5.0-next.1

Your semantic-release bot 📦🚀