https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99575
Bug ID: 99575
Summary: [coroutines] unexpected move when co_awaiting a
nonmoveable object
Product: gcc
Version: 10.2.1
Status: UNCONFIRMED
Keywords: rejects-valid
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: lemourin at gmail dot com
Target Milestone: ---
```
#if __has_include(<coroutine>)
#include <coroutine>
namespace stdx {
using std::coroutine_handle;
using std::noop_coroutine;
using std::suspend_always;
using std::suspend_never;
} // namespace stdx
#elif __has_include(<experimental/coroutine>)
#include <experimental/coroutine>
namespace stdx {
using std::experimental::coroutine_handle;
using std::experimental::noop_coroutine;
using std::experimental::suspend_always;
using std::experimental::suspend_never;
} // namespace stdx
#else
#error "coroutines unsupported"
#endif
class Task {
public:
struct promise_type {
Task get_return_object() { return Task{}; }
stdx::suspend_always initial_suspend() { return {}; }
stdx::suspend_always final_suspend() noexcept { return {}; }
void unhandled_exception() {}
void return_void() {}
};
bool await_ready() const { return false; }
void await_suspend(stdx::coroutine_handle<void> continuation) {}
void await_resume() {}
};
class NonMoveableTask {
public:
NonMoveableTask() = default;
NonMoveableTask(const NonMoveableTask&) = delete;
NonMoveableTask(NonMoveableTask&&) = delete;
NonMoveableTask& operator=(const NonMoveableTask&) = delete;
NonMoveableTask& operator=(NonMoveableTask&& other) = delete;
bool await_ready() const { return false; }
void await_suspend(stdx::coroutine_handle<void>) {}
void await_resume() {}
};
Task Foo(NonMoveableTask* task) { co_await* task; }
int main() {}
```
The above code snippet does not compile with gcc with the following error log:
`
move.cc: In function ‘Task Foo(NonMoveableTask*)’:
move.cc:50:45: error: use of deleted function
‘NonMoveableTask::NonMoveableTask(NonMoveableTask&&)’
50 | Task Foo(NonMoveableTask* task) { co_await* task; }
| ^~~~
move.cc:40:3: note: declared here
40 | NonMoveableTask(NonMoveableTask&&) = delete;
| ^~~~~~~~~~~~~~~
make: *** [<builtin>: move] Error 1
`
clang and msvc accept it. If the move constructor is available code compiled
with gcc uses it and leaves `task` in a moved from state.
