vb.net-“with”和闭包不混合

我想我会分享这个以防其他人碰到这个。
我今天做了类似的事情,花了一段时间才弄明白为什么这会在运行时引起问题。

此代码:

Public Class foo
  Public bar As String = "blah"
End Class

Public Sub DoInline()
  Dim o As New foo
  Dim f As Func(Of String)
  With o
    f = Function() .bar
  End With
  Try
    Console.WriteLine(f.DynamicInvoke())
  Catch ex As Reflection.TargetInvocationException
    Console.WriteLine(ex.InnerException.ToString)
  End Try
End Sub

引发NullReferenceException。似乎with使用闭包作为临时存储,在“end with”中,它将闭包的变量设置为Nothing。

这是红门反射镜的代码:

Public Shared Sub DoInline()
    Dim o As New foo
    Dim $VB$Closure_ClosureVariable_7A_6 As New _Closure$__1
    $VB$Closure_ClosureVariable_7A_6.$VB$Local_VB$t_ref$L0 = o
    Dim f As Func(Of String) = New Func(Of String)(AddressOf $VB$Closure_ClosureVariable_7A_6._Lambda$__1)
    $VB$Closure_ClosureVariable_7A_6.$VB$Local_VB$t_ref$L0 = Nothing 
    Try 
        Console.WriteLine(RuntimeHelpers.GetObjectValue(f.DynamicInvoke(New Object(0  - 1) {})))
    Catch exception1 As TargetInvocationException
        ProjectData.SetProjectError(exception1)
        Console.WriteLine(exception1.InnerException.ToString)
        ProjectData.ClearProjectError
    End Try
End Sub

注意到

$VB$Closure_ClosureVariable_7A_6.$VB$Local_VB$t_ref$L0 = Nothing 

我真正能问的唯一“问题”是:这是一个bug还是一个奇怪的设计决策,出于某种原因我看不到。 从现在开始,我基本上是要避免使用“with”。