[Bug c++/67768] New: Second and subsequent captured variable in variadic template unpaking are default constructed

[Bug c++/67768] New: Second and subsequent captured variable in variadic template unpaking are default constructed

[dtyazskwindows7 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67768

            Bug ID: 67768
           Summary: Second and subsequent captured variable in variadic
                    template unpaking are default constructed
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dtyazskwindows7 at gmail dot com
  Target Milestone: ---

When you compile and run the following code in gcc6.0
=================================
#include<iostream>
#include<utility>
#include<tuple>

template<std::size_t I,class T>T echo(T v)
{
    return v;
}
template<std::size_t... Is>auto run(std::index_sequence<Is...>)
{
    int x = 10;
    return std::make_tuple(echo<Is>([y=x](){std::cout<<y<<std::endl;})...);
}

int main()
{
    auto v = run(std::make_index_sequence<3>());
    std::get<0>(v)();
    std::get<1>(v)();
    std::get<2>(v)();
}
========================================
output is as follows:
10
0
0

[Bug c++/67768] Second and subsequent captured variable in variadic template unpaking are default constructed

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67768

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|UNCONFIRMED                 |RESOLVED
   Target Milestone|---                         |8.0

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed in GCC 8. Here is a self contained testcase (no libstdc++ involved):
template<int I,class T>T echo(T v) { return v; }

template<typename ...T> struct run1;
template<> struct run1<>{};
template<typename T> struct run1<T>{run1(T a){a();}};
template<typename T, typename ...T1>
struct run1<T, T1...>
  : run1<T1...>{run1(T a, T1... b) : run1<T1...>(b...) {a();}};

template<typename ...T>
void run11(T... a)
{
  run1<T...>(a...);
}
template<int... Is>void run(void)
{
    int x = 10;
    run11(echo<Is>([y=x](){if (y!=10) __builtin_abort();})...);
}
int main()
{
    run<0,1,2>();
}

-------- CUT ----------