Compiler Error 266

you have a namespace and a local that are the same; i.e.

namespace other { namespace mine { int ii; } }
using namespace other;
int mine;
int func() {
    return mine; // the compiler can not tell if this is the namespace or the local.
}

the solution can be as simple as qualifying thus;

namespace other { namespace mine { int ii; } }
using namespace other;
int mine;
int func() {
    return ::mine; // the compiler it being told it is the local.
}
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