VB -> C#: Incorrect conversion of `If` immediately preceded by `Else`

Seems like a pretty serious bug, as it may screw up control flow significantly and lead to completely unexpected results.

VB.Net input code

If OUTER Then
  If FOO1 Then Bar1() : Exit Sub
Else 'NOT OUTER
  If FOO2 Then
    Bar2()
    Exit Sub
  End If
End If 'OUTER

Erroneous output

if (OUTER)
  if (FOO1) {
    Bar1();
    return;
  } else if (FOO2) {
    Bar2();
    return;
  }

Expected output

if (OUTER) {
  if (FOO1) {
    Bar1();
    return;
  }
} else { //NOT OUTER
  if (FOO2) {
    Bar2();
    return;
  }
}

Details

• Product in use: VS extension
• Version in use: latest - 8.4.5.0

[GrahamTheCoder]

I did make an attempt at reproing within roslyn, but got bogged down by trying to find an existing type of test to fit this in with and ran out of time. Will try again when I have more time. For the workaround locally, I can’t manage to construct an option to override the one mentioned since so much is internal. We could of course stop using the document options altogether but I feel like that’s a degradation. Unless with fresh eyes anyone can figure out how to get at the option we need, we’ll likely need to use some reflection hackery unfortunately.

[GrahamTheCoder]

Debugging through, I can see that the issue is indeed introduced here: https://github.com/icsharpcode/CodeConverter/blob/068c7dd9ec06ec32d51794bfd2f0e0c40fb7114e/CodeConverter/Shared/DocumentExtensions.cs#L110-L112 This looks like a bug in roslyn. I’ll try to repro purely against that library and file/fix upstream if I can.

Even if the fix was made today, we couldn’t rely on everyone using a version of VS containing it for years, so it’s worth a fix/workaround given the severity. In the file I referenced you can see it does grab the options from the Document (which Visual Studio controls). Originally I’d hoped this would include editorconfig stuff, though I’ve seen no evidence of that ever working. You can see in that file I’ve overridden one of the VB options, and I will see if I can do the same for this case.