Proposed resolution (approved by CWG 2023-07-14):

Change in 9.5.4 [dcl.fct.def.coroutine] paragraph 4 as follows:

In the following, pi is an lvalue of type Pi , where p1 denotes the object parameter and pi+1 denotes the ith non-object function parameter for a non-static an implicit object member function, and pi denotes the ith function parameter otherwise. For a non-static an implicit object member function, q1 is an lvalue that denotes *this; any other qi is an lvalue that denotes the parameter copy corresponding to pi, as described below.

[Accepted as a DR at the November, 2023 meeting.]

Subclause 9.5.4 [dcl.fct.def.coroutine] paragraph 4 specifies:

In the following, pi is an lvalue of type Pi , where p1 denotes the object parameter and pi+1 denotes the ith non-object function parameter for a non-static member function, and pi denotes the ith function parameter otherwise. For a non-static member function, q1 is an lvalue that denotes *this; any other qi is an lvalue that denotes the parameter copy corresponding to pi , as described below.

An explicit object member function is a non-static member function, but there is no this.