Unexpected quick info type display when `dynamic` is involved

[DoctorKrolic]

Version Used:
Latest VS 2026 [11201.2]

Steps to Reproduce:

void M(dynamic d)
{
    DateTime? dt = default;
    var c = dt ??= d;
}

Hover over ??= and var

Expected Behavior:
In both cases I see DateTime? as a type

Actual Behavior:

Note, that for whatever reason in one case the constraint is struct while in other it is struct?, although both types should be just DateTime?

[CyrusNajmabadi]

I'm not understanding the problem here.

In both cases I see DateTime? as a type

That's waht we show. We have Nullable<T> ... T is DateTime.

[DoctorKrolic]

If you hover over dt it will show its type as DateTime?:

So I expect Nullable<T> ... T is DateTime to be simplified to just DateTime? as well

[CyrusNajmabadi]

If you hover over dt it will show its type as DateTime?:

THat's showing "QI for a variable". Which just shows the normal info for a type.

However, when you're hovering on 'var', we're giving you "qi for a type". In that case, generics are shown in their unconstructed form, and the information about instantiation is shown below. That's unrelated to 'dynamic' and is simply how we've shown nullable (and other generics) since C# v2.

[CyrusNajmabadi]

Closing out as by design. This is just the normal display for hovering on a type that is some instantiation of Nullable<T> itself.