[Bug c++/117374] New: Strange behavior of co_yield in initializer-list

[ddvamp007 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117374

            Bug ID: 117374
           Summary: Strange behavior of co_yield in initializer-list
           Product: gcc
           Version: 14.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ddvamp007 at gmail dot com
  Target Milestone: ---

#include <coroutine>
#include <iostream>

struct Promise;

using HandleBase = std::coroutine_handle<Promise>;

struct Promise {
    HandleBase get_return_object() { return HandleBase::from_promise(*this); }
    std::suspend_always initial_suspend() { return {}; }
    std::suspend_always final_suspend() noexcept { return {}; }
    void return_void() {}
    void unhandled_exception() {}

    int x = -1;

    auto yield_value(int value) {
        struct Awaiter {
            int &slot;
            int value;

            Awaiter(int &r, int v) : slot(r), value(v) {
                // slot = value;
            }

            bool await_ready() { return false; }
            void await_suspend(HandleBase) {}
            int await_resume() { return slot = value; }
        };

        return Awaiter(x, value);
    }
};

struct Handle : HandleBase {
    using promise_type = Promise;

    Handle(HandleBase b) : HandleBase(std::move(b)) {}

    int operator() () {
        HandleBase::operator()();
        return promise().x;
    }
};

Handle Coro() {
    int x = 0;

    int arr[] = {co_yield x++, co_yield x++, co_yield x++};

    std::cout << "In coro arr: [" << arr[0] << ", " << arr[1] << ", " << arr[2]
<< ']';
}

int main() {
    auto gen = Coro();

    int arr[] = {gen(), gen(), gen()};
    auto last = gen();

    std::cout << "\nIn main arr: [" << arr[0] << ", " << arr[1] << ", " <<
arr[2] << ']';

    std::cout << "\nlast: " << last;

    gen.destroy();

    return 0;
}

In godbolt gcc 14.2 and gcc (trunk)

This code prints:
  In coro arr: [0, 1, 2]
  In main arr: [-1, -1, -1]
  last: 2

If undo comment in Awaiter constructor:
  In coro arr: [0, 1, 2]
  In main arr: [2, 2, 2]
  last: 2