[Bug c++/95477] New: [coroutines] coroutine result object not properly freed
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95477
Bug ID: 95477
Summary: [coroutines] coroutine result object not properly
freed
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: natattak at gmail dot com
Target Milestone: ---
In some cases, the result object of a coroutine is not properly destroyed after
the coroutine finishes execution. Consider the following example:
#include
struct simple {
static inline int alive = 0;
simple() { ++alive; }
simple(simple&&) { ++alive; }
~simple() { --alive; }
struct promise_type {
simple get_return_object() { return simple{}; }
void return_void() {}
void unhandled_exception() {}
auto initial_suspend() noexcept { return std::suspend_never{}; }
auto final_suspend() noexcept { return std::suspend_never{}; }
};
};
simple f() { co_return; }
int main() {
{
f();
}
return simple::alive;
}
The return value should be 0, indicating that all created objects were
destroyed. However, when executing, I get the result 1. After commenting out
the move constructor, the return value is 0 as expected.
See also:
https://stackoverflow.com/questions/62125871/simple-coroutine-leaking-with-gcc-10
This is compiled using `-std=c++20 -fcoroutines`.
My `gcc -v` is:
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/10.1.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/gcc/src/gcc/configure --prefix=/usr --libdir=/usr/lib
--libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=https://bugs.archlinux.org/
--enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++,d --with-isl
--with-linker-hash-style=gnu --with-system-zlib --enable-__cxa_atexit
--enable-cet=auto --enable-checking=release --enable-clocale=gnu
--enable-default-pie --enable-default-ssp --enable-gnu-indirect-function
--enable-gnu-unique-object --enable-install-libiberty --enable-linker-build-id
--enable-lto --enable-multilib --enable-plugin --enable-shared
--enable-threads=posix --disable-libssp --disable-libstdcxx-pch
--disable-libunwind-exceptions --disable-werror
gdc_include_dir=/usr/include/dlang/gdc
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.1.0 (GCC)
[Bug c++/96533] New: ICE with -Wunused-parameter when using three-way comparison
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96533
Bug ID: 96533
Summary: ICE with -Wunused-parameter when using three-way
comparison
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: natattak at gmail dot com
Target Milestone: ---
Minimal example:
#include
#include
struct S {
// making it a member fixes the issue
friend auto operator<=>(S, S) = default;
};
// removing 'rhs' fixes the issue
template
auto operator<(Lhs&&, Rhs&& rhs) {
return true;
}
int main() {
// using operator< directly fixes the issue
//return S{} < S{};
return std::less{}(S{}, S{});
}
Compiled with `g++ -std=c++20 -Wunused-parameter`. Output:
'
Internal compiler error: Error reporting routines re-entered.
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://gcc.gnu.org/bugs/> for instructions.
First noticed on g++ 10.1, tested on compiler explorer with current trunk:
https://godbolt.org/z/85j8TW
[Bug c++/96533] ICE with -Wunused-parameter when using three-way comparison
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96533
--- Comment #1 from Nathaniel Shead ---
On further investigation, I suspect this is more general than just
`-Wunused-parameter`; the error looks to be caused by any error occurring
within `operator<`. For example,
#include
#include
struct S {};
auto operator<=>(S, S) = default;
template
auto operator<(Lhs&&, Rhs&& rhs) {
return rhs.nonexistent;
}
int main() {
return std::less{}(S{}, S{});
}
produces the same issue.
I also discovered that the issue is only when the templated `operator<` has
deduced type.
[Bug c++/96533] ICE with three-way comparison when error occurs in templated operator< overload
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96533
Nathaniel Shead changed:
What|Removed |Added
Summary|ICE with -Wunused-parameter |ICE with three-way
|when using three-way|comparison when error
|comparison |occurs in templated
||operator< overload
--- Comment #2 from Nathaniel Shead ---
(Correction with my previous comment, apologies; should be
struct S {};
auto operator<=>(S, S) { return std::strong_ordering::equal; }
— see https://godbolt.org/z/aPxv8d, or otherwise a friend as in my first post.)
[Bug c++/97566] New: [[no_unique_address]] causes miscompiles when mixed with EBO in constexpr context
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97566
Bug ID: 97566
Summary: [[no_unique_address]] causes miscompiles when mixed
with EBO in constexpr context
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: natattak at gmail dot com
Target Milestone: ---
Example: (https://godbolt.org/z/Y5q5br)
#include
#include
// error disappears if E doesn't inherit from B
struct B {};
struct E : B {};
struct counter {
constexpr counter() = default;
constexpr void inc() {
size++;
}
// error disappears if you remove or reorder this value
int unused = 0;
int size = 0;
[[no_unique_address]] E empty = {};
};
constexpr int test() {
counter x;
x.inc();
return x.size;
}
int main() {
assert(test() == 1);// works, unless optimisations enabled
static_assert(test() == 1); // fails, always
}
In particular, the runtime assertion only passes on -O0; any higher
optimisation e.g. -O1 causes it to fail.
Compiled as `g++ -std=c++20`.
