------- Comment #3 from bangerth at dealii dot org 2006-03-08 14:59 ------- I didn't make up the rules, so you're barking up the wrong tree :-)
But the difference between using directives for names and namespace aliases is that a using directive is final: it imports a name into the present namespace. The namespace alias provides an alternative name for a namespace, but the namespace name it points to may itself be an alias, which means that the compiler may have to walk a fairly long chain of aliases until it finally finds the original. W. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26448
