VB -> C#: Pulling variables before the loop can rename variables in an unexpected way.

[Yozer]

VB.Net input code

Private Sub TestMethod()
    For i = 1 To 2
        If i = 1 Then
            Dim a As Integer
            a += 1
            System.Console.WriteLine(a)
        End If
    Next
End Sub

Erroneous output

private void TestMethod()
{
    var a = default(int);
    for (int i = 1; i <= 2; i++)
    {
        if (i == 1)
        {
            ph38013f178570470fb7aea44e2e2f4f41 += 1;
            System.Console.WriteLine(ph38013f178570470fb7aea44e2e2f4f41);
        }
    }
}

Expected output

private void TestMethod()
{
    var a = default(int);
    for (int i = 1; i <= 2; i++)
    {
        if (i == 1)
        {
            a+= 1;
            System.Console.WriteLine(a);
        }
    }
}

Details

• Product in use: e.g. codeconverter.icsharpcode.net / VS extension / both
• Version in use: e.g. 5.6.3 or a commit hash (if it's a 3rd party tool using this library, try one of the above) https://github.com/icsharpcode/CodeConverter/commit/dce1ab91d43e437e83e8127267436ae7bfb0bb9e
• Did you see it working in a previous version, which?
• Any other relevant information to the issue, or your interest in contributing a fix.

I can try to take a look, probably the issue is related to nested scope that is not a loop.

[Yozer]

Another problem. Probably a bit more serious. My guess is that we throw duplicated key exceptions from the dictionary that handles renaming.

Private Sub TestMethod2()
    For i = 1 To 2
        If i = 1 Then
            Dim a As Integer
            a += 1
            System.Console.WriteLine(a)
        Else If i = 2 Then
            Dim a As Integer
            a += 1
            System.Console.WriteLine(a)
        End If
    Next
End Sub

private void TestMethod2()
{
    var a = default(int);
    for (int i = 1; i <= 2; i++)
        ;
}

It's a bit surprising to me that we don't create here some kind of #error directive.

[Yozer]

And third issue. Still related to renaming so I will keep it under this issue.

Public Class Data
    Public Property a as Integer
End Class

Public Class VisualBasicClass
    Private Sub TestMethod3()
        For j= 1 To 2
            For i = 1 To 2
                Dim a As Integer
                If i = 1 Then
                    Dim d as New Data
                    a += 1
                    System.Console.WriteLine(a)
                    System.Console.WriteLine(d.a)
                End If
            Next
        Next
    End Sub
End Class

var a1 = default(int);
for (int j = 1; j <= 2; j++)
{
    for (int i = 1; i <= 2; i++)
    {
        if (i == 1)
        {
            var d = new Data();
            a1 += 1;
            System.Console.WriteLine(a1);
            System.Console.WriteLine(d.a1);
        }
    }
}

1. We renamed a variable unrelated to the variable being pulled before the loop. Current renaming logic makes a text comparison on Identifiers
2. Not really an issue but we didn't have to do renaming here as there is no conflicting variable.