https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70511
Bug ID: 70511
Summary: tuple constructor from elements hides copy constructor
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: ivan.lelann at free dot fr
Target Milestone: ---
This code compiles fine :
#include <iostream>
#include <tuple>
#include <boost/any.hpp>
int main()
{
boost::any val = 12.0;
std::tuple<boost::any> tuple_test {val};
std::cout << std::get<0>(tuple_test).type().name() << std::endl;
std::tuple<boost::any> tuple_test_copy {tuple_test};
std::cout << std::get<0>(tuple_test_copy).type().name() << std::endl;
}
and prints :
d
St5tupleIJN5boost3anyEEE
Because tuple_test_copy is not copy constructed.
It is contructed from element, with implicit conversion to boost::any.
https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/include/std/tuple#L621
My guess it that the forwarding constructor link above here hides copy
constructor, becauses it hides the fact that a conversion will ultimately
happen.
