yield immediate value?

[CarterLi]

coro::enumerable<int> test() {
    co_yield 1;
}

test.cpp:5:14: error: non-const lvalue reference to type 'coro::enumerable<int>::value_type' (aka 'int') cannot bind to a temporary of type 'int'
    co_yield 1;
             ^
../interface/coroutine/yield.hpp:83:36: note: passing argument to parameter 'ref' here
        auto yield_value(reference ref) noexcept {

[luncliff]

@CarterLi enumerable should be used with reference.
Most of generators are allowing T&&, but it doesn't.

coroutine/interface/coroutine/yield.hpp

Lines 82 to 86 in 5ddc501

	// `co_yield` expression. only for reference
	auto yield_value(reference ref) noexcept {
	current = std::addressof(ref);
	return suspend_always{};
	}

The reason for such restriction is to enforce users to reuse existing variable in the coroutine frame.
For example, the code below is reusing the object io_task_t task{};.

coroutine/modules/net/io_linux.cpp

Lines 17 to 26 in 5ddc501

	auto enumerate_net_tasks(nanoseconds timeout) noexcept(false)
	-> coro::enumerable<io_task_t> {
	const int half_time = duration_cast<milliseconds>(timeout).count() / 2;
	io_task_t task{};
	for (auto event : inbound.wait(half_time))
	co_yield task = io_task_t::from_address(event.data.ptr);
	for (auto event : outbound.wait(half_time))
	co_yield task = io_task_t::from_address(event.data.ptr);
	}

[CarterLi]

But it's ugly.

coro::enumerable<int> test() {
    int i = 1;
    co_yield i;
}

[luncliff]

Well, indeed I agree with the point. Let me change that.
But I couldn't work on this project recently and probably the state will remain unchanged for more upcoming weeks... I'm really sorry about that. I will work as soon as possible and let you know.

If you're in an urgent situation, you can try existing generator implementations in https://github.com/Quuxplusone/coro. I strongly recommend those works.