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* [Bug c++/101244] New: Wrong path in coroutine returning ternary
@ 2021-06-28 13:42 victor.burckel at gmail dot com
2021-06-28 13:43 ` [Bug c++/101244] " victor.burckel at gmail dot com
2021-11-12 4:07 ` pinskia at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: victor.burckel at gmail dot com @ 2021-06-28 13:42 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101244
Bug ID: 101244
Summary: Wrong path in coroutine returning ternary
Product: gcc
Version: 11.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: victor.burckel at gmail dot com
Target Milestone: ---
In a coroutine returning a ternary expression with co_await, the co_await part
seems to be evaluated whatever the result of the condition:
See it on godbolt, I added a check of coro.done in the resume operation to
avoid a crash in the clang part as the coroutine is voluntarily resumed one
extra time
https://godbolt.org/z/vzGKoP8d3
#include <fmt/core.h>
#include <coroutine>
#include <functional>
#ifdef __clang__
namespace std::experimental {
using std::coroutine_handle;
using std::coroutine_traits;
} // namespace std::experimental
#endif
struct task {
struct promise_type;
using handle_type = std::coroutine_handle<promise_type>;
struct promise_type {
auto initial_suspend() noexcept { return std::suspend_always{}; }
auto final_suspend() noexcept { return std::suspend_always{}; }
void return_value(int v) noexcept { value = v; }
task get_return_object() noexcept {
return task{handle_type::from_promise(*this)};
}
void unhandled_exception() noexcept {}
int value{};
};
task(handle_type h) : h{h} {}
~task() {
if (h) {
fmt::print("destroying coroutine\n");
h.destroy();
fmt::print("coroutine destroyed\n");
}
}
bool await_ready() const noexcept { return false; }
bool await_suspend(std::coroutine_handle<>) noexcept {
h.resume();
return true;
}
int await_resume() noexcept { return h.promise().value; }
void resume() {
if (!h.done()) h.resume();
}
handle_type h;
};
struct S {
S() { fmt::print("S::S()\n"); }
S(const S&) { fmt::print("S::S(const S&)\n"); }
S(S&&) { fmt::print("S::S(S&&)\n"); }
~S() { fmt::print("S::~S()\n"); }
};
task g(S) {
fmt::print("in g()\n");
co_return 1;
}
task f(bool b) {
fmt::print("calling g()\n");
co_return b ? co_await g(S{}) : 2;
}
int main() {
auto task = f(false);
fmt::print("resuming f\n");
task.resume();
fmt::print("resuming f\n");
task.resume();
}
Gcc outputs
resuming f
calling g()
S::S()
S::S(S&&)
in g()
resuming f
destroying coroutine
S::~S()
coroutine destroyed
S::~S()
destroying coroutine
coroutine destroyed
While clang outputs
resuming f
calling g()
resuming f
destroying coroutine
coroutine destroyed
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c++/101244] Wrong path in coroutine returning ternary
2021-06-28 13:42 [Bug c++/101244] New: Wrong path in coroutine returning ternary victor.burckel at gmail dot com
@ 2021-06-28 13:43 ` victor.burckel at gmail dot com
2021-11-12 4:07 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: victor.burckel at gmail dot com @ 2021-06-28 13:43 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101244
--- Comment #1 from Victor Burckel <victor.burckel at gmail dot com> ---
If ternary is not put in the co_return part but split into assignement return,
the compiler crashes
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101149
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c++/101244] Wrong path in coroutine returning ternary
2021-06-28 13:42 [Bug c++/101244] New: Wrong path in coroutine returning ternary victor.burckel at gmail dot com
2021-06-28 13:43 ` [Bug c++/101244] " victor.burckel at gmail dot com
@ 2021-11-12 4:07 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-11-12 4:07 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101244
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2021-11-12
Ever confirmed|0 |1
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed on the trunk. Note if you don't want to use the fmt library in this
case you can replace fmt::print with __builtin_printf as the program here does
not use any special part of the fmt library.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-06-28 13:42 [Bug c++/101244] New: Wrong path in coroutine returning ternary victor.burckel at gmail dot com
2021-06-28 13:43 ` [Bug c++/101244] " victor.burckel at gmail dot com
2021-11-12 4:07 ` pinskia at gcc dot gnu.org
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