ByRef Me for Structure about vblang

[VBAndCs]

I like this.
I previously proposed to allow us to optionally add ByRef to ref arguments for better clarity of code. But, I don't think both proposals will happen as they need language changes which is not valid now.

[DualBrain]

I would argue that the underlying behavior is broken (or the documentation is, at the very least, misleading)...

Module ByrefTest

  Structure PDQ
    Public P As Integer
    Public D As Decimal
    Public Q As Long
    Sub FooBar()
      ByrefTest.FooBar(Me)
    End Sub
  End Structure

  Sub FooBar(ByRef dst As PDQ)
    dst.P = 123
  End Sub

  Sub Main()
    Dim o As PDQ = Nothing
    o.FooBar()
    ' Prints 0... expecting it to be 123.
    Console.WriteLine($"{o.P}")
  End Sub

End Module

I slightly modified the original code to reflect the point that, according to the documentation found at:

https://docs.microsoft.com/en-us/dotnet/visual-basic/language-reference/modifiers/byref?f1url=%3FappId%3DDev16IDEF1%26l%3DEN-US%26k%3Dk(vb.ByRef);k(DevLang-VB)%26rd%3Dtrue

It states that the ByRef keyword "specifies that an argument is passed in such a way that the called procedure can change the value of a variable underlying the argument in the calling code."

I don't see the need to have to specify ByRef in both places. If the method specifies that it is ByRef that should be enough. If you wanted to force it to be ByVal (for whatever reason), we already have a mechanism in place to override that behavior. The problem as I see it is that the documentation suggests one thing but the implementation clearly doesn't follow what the docs specify.

[DualBrain]

To further illustrate why I believe this is a bug...

Module ByrefTest

  Structure PDQ
    Public P As Integer
    Public D As Decimal
    Public Q As Long
    Sub FooBar()
      ByrefTest.FooBar(Me)
    End Sub
  End Structure

  Sub FooBar(ByRef dst As PDQ)
    dst.P = 123
  End Sub

  Sub Main1()
    Dim o As PDQ = Nothing
    o.FooBar() ' Call FooBar within the structure...
    Console.WriteLine($"{o.P}") ' Output: 0
    FooBar(o) ' Call FooBar outside of the structure...
    Console.WriteLine($"{o.P}") ' Output: 123
  End Sub

End Module

If I modify the sample so that FooBar is called slightly differently, I get two different results... event though I'm essentially executing the same code. The only difference is the usage of Me.