This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 116a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-12-19
[Accepted at the November, 2020 meeting as part of paper P1787R6 and moved to DR at the February, 2021 meeting.]
N3690 comment CA 21Consider the following example:
template <typename T> struct B { };
namespace N {
namespace L {
template <int> void A();
}
namespace M {
template <int> struct A { typedef int y; };
}
using namespace L;
using namespace M;
}
B<N::/*template */A<0>::y> (x);
Which A is referenced in the last line? According to 6.5.5 [basic.lookup.qual] paragraph 1,
If a :: scope resolution operator in a nested-name-specifier is not preceded by a decltype-specifier, lookup of the name preceding that :: considers only namespaces, types, and templates whose specializations are types.
It is not clear whether this applies to the example or not, and the interpretation of the < token depends on the result of the lookup.
Notes from the September, 2013 meeting:
The restricted lookup mentioned in 6.5.5 [basic.lookup.qual] paragraph 1 is based on a one-token lookahead; because the next token following A in the example is not ::, the restricted lookup does not apply, and the result is ambiguous. Uncommenting the template keyword in the example does not affect the lookup.