diff options
author | Jonathan Wakely <jwakely@redhat.com> | 2022-12-15 09:52:48 +0000 |
---|---|---|
committer | Jonathan Wakely <jwakely@redhat.com> | 2023-06-23 13:45:43 +0100 |
commit | b272bc0fbf84454cae8c02e7404cfb23641380cd (patch) | |
tree | e86652ddb85a089041f81c4b30025bccb2538039 | |
parent | 7dba69b5e9977408921c635681a0daa34b813e16 (diff) |
libstdc++: Fix self-move for std::weak_ptr [PR108118]
I think an alternative fix would be something like:
_M_ptr = std::exchange(rhs._M_ptr, nullptr);
_M_refcount = std::move(rhs._M_refcount);
The standard's move-and-swap implementation generates smaller code at
all levels except -O0 and -Og, so it seems simplest to just do what the
standard says.
libstdc++-v3/ChangeLog:
PR libstdc++/108118
* include/bits/shared_ptr_base.h (weak_ptr::operator=):
Implement as move-and-swap exactly as specified in the standard.
* testsuite/20_util/weak_ptr/cons/self_move.cc: New test.
(cherry picked from commit 92eb0adc14a5f84acce7e5bc780b81b1544b24aa)
-rw-r--r-- | libstdc++-v3/include/bits/shared_ptr_base.h | 4 | ||||
-rw-r--r-- | libstdc++-v3/testsuite/20_util/weak_ptr/cons/self_move.cc | 19 |
2 files changed, 20 insertions, 3 deletions
diff --git a/libstdc++-v3/include/bits/shared_ptr_base.h b/libstdc++-v3/include/bits/shared_ptr_base.h index 792d8344664..c66d895997d 100644 --- a/libstdc++-v3/include/bits/shared_ptr_base.h +++ b/libstdc++-v3/include/bits/shared_ptr_base.h @@ -1700,9 +1700,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION __weak_ptr& operator=(__weak_ptr&& __r) noexcept { - _M_ptr = __r._M_ptr; - _M_refcount = std::move(__r._M_refcount); - __r._M_ptr = nullptr; + __weak_ptr(std::move(__r)).swap(*this); return *this; } diff --git a/libstdc++-v3/testsuite/20_util/weak_ptr/cons/self_move.cc b/libstdc++-v3/testsuite/20_util/weak_ptr/cons/self_move.cc new file mode 100644 index 00000000000..c890d2ba94d --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/weak_ptr/cons/self_move.cc @@ -0,0 +1,19 @@ +// { dg-do run { target c++11 } } + +#include <memory> +#include <testsuite_hooks.h> + +void +test_self_move() +{ + std::shared_ptr<int> sp(new int(66)); + std::weak_ptr<int> wp(sp); + wp = std::move(wp); // PR libstdc++/108118 + std::shared_ptr<int> sp2(wp); + VERIFY(sp2 == sp); +} + +int main() +{ + test_self_move(); +} |