https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95736
Bug ID: 95736
Summary: coroutine method improperly copies awaitable
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mizvekov at gmail dot com
Target Milestone: ---
Created attachment 48752
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48752&action=edit
example reproduction
Compiling attached program with `g++ -std=c++20 -fcoroutines -O0 -ggdb3
test.cc` and then running gives unexpected result:
```
coro begin
suspending to footable 0x7fffee14dee0
operator() on 0x7ffff5c307e0
a.out: test.cc:33: void footable::operator()(): Assertion `handle' failed.
fish: “./a.out” terminated by signal SIGABRT (Abort)
```
Expected result, as obtained from clang with `clang++ -std=c++20 -stdlib=libc++
-O0 -ggdb3 test.cc`:
```
coro begin
suspending to footable 0x7ffff6441330
operator() on 0x7ffff6441330
resuming from footable 0x7ffff6441330
coro end
coro returns
final suspend
releasing
done
```
Notice how on the gcc (first) case, it fails because `await_suspend` and
`operator()` are operating on different copies of the awaiter, even though the
awaiter is not copy constructible.
I failed to reproduce this problem if the coroutine body was not a class
method.
Compiler explorer workspace for convenience: https://godbolt.org/z/_yqwCV
