Variable declared inside a for loop. How do I make this to a compile time error?

Question

Today I investigated a logical bug in our software and figured out that this is related to the way VB.NET thread variables inside a loop.

Let\'s say I have the follo

Answer 1

Look at the code below. If not allowing a declaration without an initialization is a compiler error, then this code would not produce the correct output (a running total of even numbers). If you force me to initialize the value of 'total', then the method can never be correct.

Dim numbers As New List(Of Integer) From {1, 2, 3, 4, 5, 6, 8, 9, 10}
For Each number As Integer In numbers

    Dim total As Integer

    Dim isEven As Boolean = (number Mod 2 = 0)

    If isEven Then
        total += number
        Console.WriteLine("Running Total: {0}", total)
    End If
Next

Instead of adding an error, just fix the logic in the code. I don't see this as a particularly dangerous pitfall. Most programmers would be able to recognize this issue, and unit testing should also help to uncover these types of issues.