https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98704
Bug ID: 98704 Summary: coroutine_handle::done() == false after promise's unhandled_exception() has thrown Product: gcc Version: 11.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: m.kra...@tu-harburg.de Target Milestone: --- Created attachment 49981 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49981&action=edit Reproducer [dcl.fct.def.coroutine]/14 says: "If the evaluation of the expression promise.unhandled_exception() exits via an exception, the coroutine is considered suspended at the final suspend point". So, after this exception has propagated to the caller, I expect that the coroutine_handle's done() function returns true (because of [coroutine.handle.observers]/3 "Returns: true if the coroutine is suspended at its final suspend point, otherwise false"). However, the compiler for which I am reporting this makes done() return false in this situation. See the attached example code (my expectation is 1 instead of 0 in the final two lines of output). By the way, gcc 10.2, gcc trunk, clang 10.0.0, clang trunk, msvc 14.28 all behave in this way. See the short discussion on Slack Cpplang #coroutines starting on 02-Jan-2021. A fix for msvc is already underway: https://developercommunity.visualstudio.com/content/problem/1305540/coroutine-handledone-false-after-promises-unhandle.html