Can a string declared outside a lock and used within a lock be changed by another thread?

Is the following co开发者_StackOverflow社区de thread-safe? I assume it is because strings are immutable. (Code thrown together for demo purposes)

static readonly object _lockObject = new object();

void SomeMethod(string filePath, string fileName)
{
    // Any reason for this to be moved inside the lock?
    string s = Path.Combine(filePath, fileName);

    lock (_lockObject)
    {
       try
       {
          // Other stuff to create the file here. 
       }
       finally
       {
          File.Delete(s);
       }
    }
}

I'm curious after reading this (first few lines of the section Locking and Atomicity).

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Yes, it's thread-safe.

Even removing the lock would make it thread safe :-)

You're only using local variables and static BCL methods (which are always thread-safe).

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Strings are immutable so they will never change after being constructed. and since you're local is not passed by ref anywhere the reference won't change either so it safe

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It's thread-safe, but any exception thrown by File.Delete will replace the real exception when the stack unwinds.