https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103358
Bug ID: 103358
Summary: what is the first constructor argument of lambda
coroutine promise_type?
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: netcan1996 at gmail dot com
Target Milestone: ---
the C++20 standard(N4858) says:
> promise-constructor-arguments is determined as follows: overload resolution
> is performed on a promise
constructor call created by assembling an argument list with lvalues p1 . . .
pn. If a viable constructor is
found (12.4.3), then promise-constructor-arguments is (p1 , . . . , pn),
otherwise promise-constructor-
arguments is empty.
I tested gcc-12 coroutine feature, when I use the free coroutine function,
arguments are that function, but when I use lambda coroutine, the first
argument looks strange, the rest arguments are the same as lambda.
```cpp
auto test = [](int, char, double) -> task<void> {
co_return;
};
```
the promise_type dumps all arguments type:
```cpp
template<typename ...T>
promise_type(T&&... args) {
dump<T...> {};
}
```
T = {const<lambda(int, char, double)>&&, int&, char&, double&} here, what is
the type `const<lambda(int, char, double)>&&`?
