This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 110b. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2023-01-15


2452. Flowing off the end of a coroutine

Section: 8.7.5  [stmt.return.coroutine]     Status: CD6     Submitter: Lewis Baker     Date: 2020-02-14

[Accepted at the November, 2020 meeting.]

There are two references to “flowing off the end of a coroutine”, specifically in 8.7.5 [stmt.return.coroutine] paragraph 3:

If p.return_void() is a valid expression, flowing off the end of a coroutine is equivalent to a co_return with no operand; otherwise flowing off the end of a coroutine results in undefined behavior.

and 9.5.4 [dcl.fct.def.coroutine] paragraph 11:

The coroutine state is destroyed when control flows off the end of the coroutine or...

These mean different things and should be clarified.

Proposed resolution (July, 2020):

Change 8.7.5 [stmt.return.coroutine] paragraph 3 as follows:

If p.return_void() is a valid expression, flowing off the end of a coroutine's function-body is equivalent to a co_return with no operand;otherwise flowing off the end of a coroutine's function-body results in undefined behavior.