Nullable(Of ) is not set to Nothing in conditional ternary operator

Question

Why I can't set Nothing to Nullable(Of Double) through conditional ternary operator but I can directly?

Dim d As Double? = Nothing
d = If(True, 0, Nothing)    ' result: d = 0
d = Nothing                 ' result: d = Nothing
d = If(False, 0, Nothing)   ' result: d = 0 Why?

Edit: These work (based on below accepted answer):

d = If(False, 0, New Integer?)
d = If(False, CType(0, Double?), Nothing)
d = If(False, 0, CType(Nothing, Double?))

Answer 1

Nothing converts to a lot of types, not just T?. It can happily convert to Double:

Function X() As Double
    Return Nothing ' result: 0.0
End Function

or to Integer. It's that sense of Nothing that you're using in If(X, 0, Nothing), because If needs the second and third arguments to match in type: it treats it as type Integer, because that's the type of 0.

Explicitly specifying one of the types as nullable (either Integer? or Double? would work) lets the compiler figure out what you want:

d = If(False, CType(0, Double?), Nothing), or d = If(False, 0, CType(Nothing, Double?))