[Bug libstdc++/79743] std::experimental::optional constructor broken in gcc 6.2

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79743

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Денис Крыськов from comment #0)
> all files mentioned in bug-report

No, because you haven't provided a standalone program that can be compiled,
because it includes gtest headers.

Here's a standalone version, which fails with 6.2 and passes with 6.3:

#include <experimental/optional>
#include <string>
#include <cassert>

class Bread_and_butter {
    public:
    std::string bread;
    std::experimental::optional<bool> butter;

    Bread_and_butter(Bread_and_butter&& source);
    Bread_and_butter() noexcept : bread(), butter() {};
    Bread_and_butter(const Bread_and_butter&) = delete;
    Bread_and_butter& operator=(const Bread_and_butter&) = delete;
    Bread_and_butter& operator=(Bread_and_butter&&) = delete;
};

Bread_and_butter::Bread_and_butter(Bread_and_butter&& source) :
    bread(source.bread),
    butter(source.butter) {
    if(bread.size() >= 5) {
        butter = true;
    }
    if(bread.size() >= 10) {
        butter = false;
    }
}

int main() {
    Bread_and_butter s0;
    auto s1 = std::move(s0);
    assert(!s1.butter);
}

I think this is a dup of PR 77288

*** This bug has been marked as a duplicate of bug 77288 ***