[Bug c++/95491] New: coroutines: awaited temporaries are never destructed

[max at duempel dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95491

            Bug ID: 95491
           Summary: coroutines: awaited temporaries are never destructed
           Product: gcc
           Version: 10.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: max at duempel dot org
  Target Milestone: ---

Created attachment 48665
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48665&action=edit
Small program demonstrating the bug

If a coroutine uses `co_await` on a temporary (i.e. the temporary lives only in
a scope that contains the suspend point), the temporary never gets destructed.

My demo with "gcc version 10.1.0 (Debian 10.1.0-3)" (Debian Bullseye/Sid):

 $ g++ -fcoroutines coroutine_leak.cxx && ./a.out
 construct Bar
 Bar() = 42

This is with "clang version 10.0.0-4":

 $ clang++ -fcoroutines-ts -stdlib=libc++ coroutine_leak.cxx && ./a.out
 construct Bar
 Bar() = 42
 destruct Bar

clang calls the destructor, and gcc doesn't. With -fsanitize=address (and a
different program which allocates a "real" coroutine instead of a class with an
"operator co_await"), I can see memory leaks being detected.