False warning for "does not need to be #included"

[ihhub]

A included file has the same namespace as current file. Included file contains in namespace using namespace which is within the file: file a.h:

namespace A
{
    class T;
}

namespace B
{
    using namespace A;
}

file b.h:

namespace B
{
    void someFunction(A a);
}

a warning does not need to be #included will be rised.