Code Inspection: Invalid use of member

[ThunderFrame]

When working with interfaces and base types, VBA can compile code that will fail at run-time.

Rubberduck should try to identify such problems at inspection-time.

UserForm1 has the following property

Public Property Get FooBar() As String
  FooBar = "FooBar"
End Property

Sub FizzBuzz()

    Dim bar As UserForm1
    Set bar = UserForm1
    Debug.Print bar.FooBar

    Dim foo As UserForm
    Set foo = UserForm1
    'This compiles but fails at run-time
    Debug.Print foo.FooBar

End Sub

[retailcoder]

Might be I'm blind, but I don't see the problem with the snippet there. Did you mean to make a Property Let accessor call? Please clarify what we're looking for here.

[retailcoder]

Oh duh

[retailcoder]

Nevermind

[comintern]

Now that we have the MemberNotOnInterfaceInspection (that doesn't pick this up), I'd classify this as a bug as opposed to a feature request.

[bclothier]

Personally, I'm a bit surprised that the sample syntax for UserForm would cause runtime errors. That is not the same behavior with the Access form.

Dim MyForm As Access.Form
Set MyForm = New Form_MyForm
MyForm.FooBar = "foo"

The FooBar member won't show on intellisense because variable is typed as a Access.Form, not Form_MyForm but it is still legal, as long the FooBar in fact exists.

We have similar situation with ADODB.Command where syntax such as MyCommand.MyStoredProcedure 123 is legal but won't be found on the ADODB.Command's interface.

So I agree with @comintern that it should be picked up by the MemberNotOnInterface inspection, to warn the users to revise their declaration or to do explicit cast to the specific type. Note that explicit cast wouldn't even apply to the ADODB.Command case, however...

[ThunderFrame]

Also a bit like the Application.Sum function in Excel.

IIRC, COM marks the interface as extensible , and RD picks that attribute up, so we should already know that the member is potentially valid.