[Bug c++/82113] New: RVO isn't applied to base class constructor call in C++17

[for.gcc.bugzilla at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82113

            Bug ID: 82113
           Summary: RVO isn't applied to base class constructor call in
                    C++17
           Product: gcc
           Version: 7.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: for.gcc.bugzilla at gmail dot com
  Target Milestone: ---

Reported on
https://stackoverflow.com/questions/46065704/why-isnt-rvo-applied-to-base-class-constructor-call-in-c17

With C++17 guaranteed copy elision, B::B() below should compile even when
Base::Base(Base&&) is deleted.

struct Base {
    Base(Base&&) = delete;
    Base& operator=(Base&&) = delete;

    Base()
    {
    }
};

Base make_base()
{
    return Base{};
}

struct A {
    A() : b(make_base()) {} // <<<--- compiles fine

    Base b;
};

#ifdef FAIL
struct B : public Base {
    B() : Base(make_base()) {} // <<<--- "Base(Base&&) is deleted"
};
#endif

example https://godbolt.org/g/w3jRuc