https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61213
Bug ID: 61213
Summary: std::forward_as_tuple and std::tuple<T&&> and any
rvalue loose data
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tower120 at gmail dot com
std::forward_as_tuple elements loose data on -O2.
Works fine with -O0
Consider the following code:
http://coliru.stacked-crooked.com/a/67499e052283bd5a
#include <iostream>
#include <tuple>
class Widget {
public:
Widget(int h) : h(h){}
int h;
};
template<typename T>
struct RvalueTest{
RvalueTest(T&& value) : value( std::forward<T>(value) ){}
T&& value;
};
int main() {
auto t = std::forward_as_tuple(Widget(12));
//auto t = std::tuple<Widget&&>(Widget(12)); // this not work also
std::cout << std::get<0>(t).h; // <-- some random value here
/// This one not work, either:
/*RvalueTest<Widget> r(Widget(12));
std::cout << r.value.h;*/
}
Code from above works fine with clang compiler.
I suspect that rvalue object life time is wrong in -O2 mode.
