I have a piece of code:

int i;

namespace A {
 namespace B {
  int i;
 }
 using namespace B;
}

namespace C {
 using namespace A;
 int j = i;
}

       I think there are only two possibilities:

1) C::j is initialized with A::B::i. If you read 7.3.4 para 2 and apply it
separately to the two using directives then A::B::i appears as if it was
declared in A because of the using directive in A. And then since A::i would
hide ::i that one will be chosen by the lookup.

2) This piece of code is illegal because there is an ambiguity between ::i and
A::B::i. If you follow 7.3.4 para 3 literally then we see both the using
directives in C and then both the i's appear as if they were declared at
global scope. That would create an ambiguity.

   What is the correct explanation?


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  sanjayp
> I have a piece of code:

int i;

namespace A
{
 namespace B // (*)
 {
  int i;
 }
 using namespace B;
}

namespace C
{
 using namespace A; // See 7.3.4 Para 3, transitivity
                           // implies using namespace B (**) aswell

 int j = i; (***)
}

>
>        I think there are only two possibilities:
>
> 1) C::j is initialized with A::B::i. If you read 7.3.4 para 2 ...
> 2) This piece of code is illegal ...
> What is the correct explanation?

Case 2 is correct.

Reading Para 7.3.4 Para 2

For the purposes of unqualified lookup, the names 'imported' from (**) are
imported into the global namespace. ie. Into the closest enclosing namespace
that contains both the using-directive (**) and the namespace
declaration (*).

Thus (***) is ambiguous.

--

Alex Jonas

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