This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 117b. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2025-08-11
239. Footnote 116 and Koenig lookupSection: 12.2.2.2.2 [over.call.func] Status: CD1 Submitter: Steve Clamage Date: 2 Aug 2000[Moved to DR at 4/01 meeting.]
In describing non-member functions in an overload set, footnote 116 (12.2.2.2.2 [over.call.func]) says,Because of the usual name hiding rules, these will be introduced by declarations or by using-directives all found in the same block or all found at namespace scope.
At least in terms of the current state of the Standard, this is not correct: a block extern declaration does not prevent Koenig lookup from occurring. For example,
enum E { zero };
void f(E);
void g() {
void f(int);
f(zero);
}
In this example, the overload set will include declarations from both namespace and block scope.
(See also issue 12.)
Proposed resolution (04/01):
In 6.5.4 [basic.lookup.argdep] paragraph 2, change
If the ordinary unqualified lookup of the name finds the declaration of a class member function, the associated namespaces and classes are not considered.
to
If the ordinary unqualified lookup of the name finds the declaration of a class member function, or a block-scope function declaration that is not a using-declaration, the associated namespaces and classes are not considered.
and change the example to:
namespace NS {
class T { };
void f(T);
void g(T, int);
}
NS::T parm;
void g(NS::T, float);
int main() {
f(parm); // OK: calls NS::f
extern void g(NS::T, float);
g(parm, 1); // OK: calls g(NS::T, float)
}
In 12.2.2.2.2 [over.call.func] paragraph 3 from:
If the name resolves to a non-member function declaration, that function and its overloaded declarations constitute the set of candidate functions.
to
If the name resolves to a set of non-member function declarations, that set of functions constitutes the set of candidate functions.
Note that this text is also edited by issue 364. Also, remove the associated footnote 116.
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