S3063 — "StringBuilder" data should be used

Why is this an issue?

StringBuilder instances that never build a string clutter the code and worse are a drag on performance. Either they should be removed, or the missing ToString() call should be added.

Noncompliant code example

Public Sub DoSomething(ByVal strings As List(Of String))
    Dim sb As StringBuilder = New StringBuilder() ' Noncompliant
    sb.Append("Got: ")

    For Each str As String In strings
        sb.Append(str).Append(", ")
    Next
End Sub

Compliant solution

Public Sub DoSomething(ByVal strings As List(Of String))
    For Each str As String In strings
    Next
End Sub

or

Public Sub DoSomething(ByVal strings As List(Of String))
    Dim sb As StringBuilder = New StringBuilder()
    sb.Append("Got: ")

    For Each str As String In strings
        sb.Append(str).Append(", ")
    Next

    My.Application.Log.WriteEntry(sb.ToString())
End Sub

Exceptions

No issue is reported when StringBuilder is:

• Accessed through sb.CopyTo(), sb.GetChunks(), sb.Length, or sb(index).
• Passed as a method argument, on the grounds that it will likely be accessed through a ToString() invocation there.
• Passed in as a parameter to the current method, on the grounds that the callee will materialize the string.
• Retrieved by a custom function (Dim sb As StringBuilder = GetStringBuilder()).
• Returned by the method.