[Union]
partial record Shape
{
    partial record Circle(double Radius);
    partial record Rectangle(double Length, double Width);
    partial record Square(double Length);
    partial record Triangle(double Base, double Height);
}

Shape? shape = null;

var sides = shape switch
{
    // This is now considered as handling both the `Circle` and `null` cases.
    Circle or null => 0,
    // This is now considered as handling both the `Rectangle` and `Square` cases.
    Rectangle or Square => 4,
    Triangle t => 3,
};

[Union]
partial record Shape
{
    partial record Circle(double Radius);
    partial record Rectangle(double Length, double Width);
    partial record Triangle(double Base, double Height);
}

Shape shape = new Circle(3.14);

var area = shape switch
{
    // This is now considered as handling the `Rectangle` case.
    Rectangle { Length: var length, Width: var width } => length * width,
    Circle(var radius) => 3.14 * radius * radius,
    Triangle t => t.Base * t.Height / 2,
};

var area2 = shape switch
{
    // This is now considered as handling the `Rectangle` case.
    Rectangle { Length: _, Width: _ } => 0,
    Circle(var radius) => 3.14 * radius * radius,
    Triangle t => t.Base * t.Height / 2,
};

using Dunet;
using static Option<int>;

[Union]
partial record Option<T>
{
    partial record Some(T Value);
    partial record None;
}

Option<int> option = new Some(42);

// Does not emit an exhaustiveness warning since all union variants are handled.
var message = option switch
{
    Some(var value) => $"The value is {value}!",
    None => "There's no value.",
};

// Emits an exhaustiveness warning because Some variant with Value != 5 is unhandled.
var message2 = option switch
{
   Some(5) => "Value is 5!",
   None => "There's no value.",
}

[Union]
public partial record Option<T>
{
    // An implicit conversion from `T` to `Some` is now generated.
    public partial record Some(T Value);
    public partial record None;
}