When you see a using statement, think of this code:
StreadReader rdr = null;
try
{
rdr = File.OpenText("file.txt");
//do stuff
}
finally
{
if (rdr != null)
rdr.Dispose();
}
So the real answer is that it doesn’t do anything with the exception thrown in the body of the using block. It doesn’t handle it or rethrow it.