This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 112c. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
[Voted into WP at March, 2010 meeting.]
According to 9.8.4 [namespace.udir] paragraph 4,
The using-directive is transitive: if a scope contains a using-directive that nominates a second namespace that itself contains using-directives, the effect is as if the using-directives from the second namespace also appeared in the first.
This is true only for unqualified lookup; the algorithm in 184.108.40.206 [namespace.qual] paragraph 2 gives different results (the transitive closure terminates when a declaration of the name being looked up is found).
Proposed resolution (October, 2009):
Change 9.8.4 [namespace.udir] paragraph 4 as follows: