This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115d. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-10-26
[Accepted at the November, 2020 meeting as part of paper P1787R6 and moved to DR at the February, 2021 meeting.]
According to 12.2.4 [over.match.best] paragraph 4, the following program appears to be ill-formed:
void f(int, int=0); void f(int=0, int); void g() { f(); }
Though I do not expect this is the intent of this paragraph in the standard.
12.2.4 [over.match.best] paragraph 4:
If the best viable function resolves to a function for which multiple declarations were found, and if at least two of these declarations or the declarations they refer to in the case of using-declarations specify a default argument that made the function viable, the program is ill-formed. [Example:namespace A { extern "C" void f(int = 5); } namespace B { extern "C" void f(int = 5); } using A::f; using B::f; void use() { f(3); //OK, default argument was not used for viability f(); //Error: found default argument twice }end example]