https://gcc.gnu.org/g:2ce99c0088ed97991f61cbdefa83f682c2ef4364
commit r15-6272-g2ce99c0088ed97991f61cbdefa83f682c2ef4364
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Sun Dec 8 14:34:01 2024 +0000
libstdc++: Fix fancy pointer support in linked lists [PR57272]
The union members I used in the new _Node types for fancy pointers only
work for value types that are trivially default constructible. This
change replaces the anonymous union with a named union so it can be
given a default constructor and destructor, to leave the variant member
uninitialized.
This also fixes the incorrect macro names in the alloc_ptr_ignored.cc
tests as pointed out by François, and fixes some std::list pointer
confusions that the fixed alloc_ptr_ignored.cc test revealed.
libstdc++-v3/ChangeLog:
PR libstdc++/57272
* include/bits/forward_list.h (__fwd_list::_Node): Add
user-provided special member functions to union.
* include/bits/stl_list.h (__list::_Node): Likewise.
(_Node_base::_M_hook, _Node_base::swap): Use _M_base() instead
of std::pointer_traits::pointer_to.
(_Node_base::_M_transfer): Likewise. Add noexcept.
(_List_base::_M_put_node): Use 'if constexpr' to avoid using
pointer_traits::pointer_to when not necessary.
(_List_base::_M_destroy_node): Fix parameter to be the pointer
type used internally, not the allocator's pointer.
(list::_M_create_node): Likewise.
*
testsuite/23_containers/forward_list/requirements/explicit_instantiation/alloc_ptr.cc:
Check explicit instantiation of non-trivial value type.
*
testsuite/23_containers/list/requirements/explicit_instantiation/alloc_ptr.cc:
Likewise.
*
testsuite/23_containers/forward_list/requirements/explicit_instantiation/alloc_ptr_ignored.cc:
Fix macro name.
*
testsuite/23_containers/list/requirements/explicit_instantiation/alloc_ptr_ignored.cc:
Likewise.
Diff:
---
libstdc++-v3/include/bits/forward_list.h | 15 ++--
libstdc++-v3/include/bits/stl_list.h | 92 +++++++++++++---------
.../explicit_instantiation/alloc_ptr.cc | 11 +++
.../explicit_instantiation/alloc_ptr_ignored.cc | 2 +-
.../explicit_instantiation/alloc_ptr.cc | 11 +++
.../explicit_instantiation/alloc_ptr_ignored.cc | 2 +-
6 files changed, 88 insertions(+), 45 deletions(-)
diff --git a/libstdc++-v3/include/bits/forward_list.h
b/libstdc++-v3/include/bits/forward_list.h
index f4a53bb4d7ef..3070ef6b1a78 100644
--- a/libstdc++-v3/include/bits/forward_list.h
+++ b/libstdc++-v3/include/bits/forward_list.h
@@ -420,25 +420,30 @@ namespace __fwdlist
using value_type = typename pointer_traits<_ValPtr>::element_type;
using _Node_ptr = __ptr_rebind<_ValPtr, _Node>;
- _Node() { }
+ _Node() noexcept { }
~_Node() { }
_Node(_Node&&) = delete;
- union {
+ union _Uninit_storage
+ {
+ _Uninit_storage() noexcept { }
+ ~_Uninit_storage() { }
+
#if ! _GLIBCXX_INLINE_VERSION
// For ABI compatibility we need to overalign this member.
alignas(__alignof__(value_type)) // XXX GLIBCXX_ABI Deprecated
#endif
value_type _M_data;
};
+ _Uninit_storage _M_u;
value_type*
_M_valptr() noexcept
- { return std::__addressof(_M_data); }
+ { return std::__addressof(_M_u._M_data); }
const value_type*
_M_valptr() const noexcept
- { return std::__addressof(_M_data); }
+ { return std::__addressof(_M_u._M_data); }
_Node_ptr
_M_node_ptr()
@@ -486,7 +491,7 @@ namespace __fwdlist
[[__nodiscard__]]
constexpr reference
operator*() const noexcept
- { return static_cast<_Node&>(*this->_M_node)._M_data; }
+ { return static_cast<_Node&>(*this->_M_node)._M_u._M_data; }
[[__nodiscard__]]
constexpr pointer
diff --git a/libstdc++-v3/include/bits/stl_list.h
b/libstdc++-v3/include/bits/stl_list.h
index 9f7d27242b60..03c4be79416f 100644
--- a/libstdc++-v3/include/bits/stl_list.h
+++ b/libstdc++-v3/include/bits/stl_list.h
@@ -199,12 +199,12 @@ namespace __list
swap(_Node_base& __x, _Node_base& __y) noexcept;
void
- _M_transfer(_Base_ptr const __first, _Base_ptr const __last);
+ _M_transfer(_Base_ptr const __first, _Base_ptr const __last) noexcept;
void
_M_hook(_Base_ptr const __position) noexcept
{
- auto __self = pointer_traits<_Base_ptr>::pointer_to(*this);
+ auto __self = this->_M_base();
this->_M_next = __position;
this->_M_prev = __position->_M_prev;
__position->_M_prev->_M_next = __self;
@@ -224,6 +224,8 @@ namespace __list
// by std::list::empty(), where it doesn't escape, and by
// std::list::end() const, where the pointer is used to initialize a
// const_iterator and so constness is restored.
+ // The standard allows pointer_to to be potentially-throwing,
+ // but we have to assume it doesn't throw to implement std::list.
_Base_ptr
_M_base() const noexcept
{
@@ -290,16 +292,24 @@ namespace __list
using value_type = typename pointer_traits<_ValPtr>::element_type;
using _Node_ptr = __ptr_rebind<_ValPtr, _Node>;
- union {
+ _Node() noexcept { }
+ ~_Node() { }
+ _Node(_Node&&) = delete;
+
+ union _Uninit_storage
+ {
+ _Uninit_storage() noexcept { }
+ ~_Uninit_storage() { }
+
value_type _M_data;
};
+ _Uninit_storage _M_u;
- _Node() { }
- ~_Node() { }
- _Node(_Node&&) = delete;
+ value_type*
+ _M_valptr() noexcept { return std::__addressof(_M_u._M_data); }
- value_type* _M_valptr() { return std::__addressof(_M_data); }
- value_type const* _M_valptr() const { return std::__addressof(_M_data); }
+ value_type const*
+ _M_valptr() const noexcept { return std::__addressof(_M_u._M_data); }
_Node_ptr
_M_node_ptr()
@@ -349,7 +359,7 @@ namespace __list
[[__nodiscard__]]
constexpr reference
operator*() const noexcept
- { return static_cast<_Node&>(*_M_node)._M_data; }
+ { return static_cast<_Node&>(*_M_node)._M_u._M_data; }
[[__nodiscard__]]
constexpr pointer
@@ -748,6 +758,12 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
rebind<typename _Node_traits::_Node>::other _Node_alloc_type;
typedef __gnu_cxx::__alloc_traits<_Node_alloc_type> _Node_alloc_traits;
+#if __cplusplus < 201103L || ! _GLIBCXX_USE_ALLOC_PTR_FOR_LIST
+ typedef _List_node<_Tp>* _Node_ptr;
+#else
+ using _Node_ptr = typename _Node_alloc_traits::pointer;
+#endif
+
struct _List_impl
: public _Node_alloc_type
{
@@ -797,42 +813,47 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
_M_get_node()
{ return _Node_alloc_traits::allocate(_M_impl, 1); }
-#if __cplusplus < 201103L || _GLIBCXX_USE_ALLOC_PTR_FOR_LIST
- void
- _M_put_node(typename _Node_alloc_traits::pointer __p) _GLIBCXX_NOEXCEPT
- { _Node_alloc_traits::deallocate(_M_impl, __p, 1); }
-#else
void
- _M_put_node(_List_node<_Tp>* __p)
+ _M_put_node(_Node_ptr __p) _GLIBCXX_NOEXCEPT
{
- // When not using the allocator's pointer type internally we must
- // convert between _Node_ptr (i.e. _List_node*) and the allocator's
- // pointer type.
+#if __cplusplus < 201103L || _GLIBCXX_USE_ALLOC_PTR_FOR_LIST
+ _Node_alloc_traits::deallocate(_M_impl, __p, 1);
+#else
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
using __alloc_pointer = typename _Node_alloc_traits::pointer;
- auto __ap = pointer_traits<__alloc_pointer>::pointer_to(*__p);
- _Node_alloc_traits::deallocate(_M_impl, __ap, 1);
- }
+ if constexpr (is_same<_Node_ptr, __alloc_pointer>::value)
+ _Node_alloc_traits::deallocate(_M_impl, __p, 1);
+ else
+ {
+ // When not using the allocator's pointer type internally we must
+ // convert __p to __alloc_pointer so it can be deallocated.
+ auto __ap = pointer_traits<__alloc_pointer>::pointer_to(*__p);
+ _Node_alloc_traits::deallocate(_M_impl, __ap, 1);
+ }
+#pragma GCC diagnostic pop
#endif
+ }
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
void
- _M_destroy_node(typename _Node_alloc_traits::pointer __p)
+ _M_destroy_node(_Node_ptr __p)
{
-#if __cplusplus >= 201103L
// Destroy the element
+#if __cplusplus < 201103L
+ _Tp_alloc_type(_M_impl).destroy(__p->_M_valptr());
+#else
_Node_alloc_traits::destroy(_M_impl, __p->_M_valptr());
// Only destroy the node if the pointers require it.
using _Node = typename _Node_traits::_Node;
using _Base_ptr = typename _Node_traits::_Node_base::_Base_ptr;
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
if constexpr (!is_trivially_destructible<_Base_ptr>::value)
__p->~_Node();
-#else
- _Tp_alloc_type(_M_impl).destroy(__p->_M_valptr());
+#pragma GCC diagnostic pop
#endif
this->_M_put_node(__p);
}
-#pragma GCC diagnostic pop
public:
typedef _Alloc allocator_type;
@@ -1084,12 +1105,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
auto __guard = std::__allocate_guarded_obj(__alloc);
_Node_alloc_traits::construct(__alloc, __guard->_M_valptr(),
std::forward<_Args>(__args)...);
- auto __p = __guard.release();
-#if _GLIBCXX_USE_ALLOC_PTR_FOR_LIST
- return __p;
-#else
- return std::__to_address(__p);
-#endif
+ return __guard.release();
}
#endif
@@ -2756,8 +2772,8 @@ namespace __list
void
_Node_base<_VoidPtr>::swap(_Node_base& __x, _Node_base& __y) noexcept
{
- auto __px = pointer_traits<_Base_ptr>::pointer_to(__x);
- auto __py = pointer_traits<_Base_ptr>::pointer_to(__y);
+ auto __px = __x._M_base();
+ auto __py = __x._M_base();
if (__x._M_next != __px)
{
@@ -2792,11 +2808,11 @@ namespace __list
template<typename _VoidPtr>
void
_Node_base<_VoidPtr>::_M_transfer(_Base_ptr const __first,
- _Base_ptr const __last)
+ _Base_ptr const __last) noexcept
{
__glibcxx_assert(__first != __last);
- auto __self = pointer_traits<_Base_ptr>::pointer_to(*this);
+ auto __self = _M_base();
if (__self != __last)
{
// Remove [first, last) from its old position.
diff --git
a/libstdc++-v3/testsuite/23_containers/forward_list/requirements/explicit_instantiation/alloc_ptr.cc
b/libstdc++-v3/testsuite/23_containers/forward_list/requirements/explicit_instantiation/alloc_ptr.cc
index 621ff4c652cb..e3bf8a13095a 100644
---
a/libstdc++-v3/testsuite/23_containers/forward_list/requirements/explicit_instantiation/alloc_ptr.cc
+++
b/libstdc++-v3/testsuite/23_containers/forward_list/requirements/explicit_instantiation/alloc_ptr.cc
@@ -59,6 +59,17 @@ struct Allocator
template class std::forward_list<int, Allocator<int>>;
+struct NonTrivial
+{
+ NonTrivial() { }
+ NonTrivial(const NonTrivial&) { }
+ ~NonTrivial() { }
+ bool operator==(const NonTrivial&) const { return true; } // for remove(T)
+ bool operator<(const NonTrivial&) const { return false; } // for sort()
+};
+
+template class std::forward_list<NonTrivial, Allocator<NonTrivial>>;
+
#include <testsuite_iterators.h>
void
diff --git
a/libstdc++-v3/testsuite/23_containers/forward_list/requirements/explicit_instantiation/alloc_ptr_ignored.cc
b/libstdc++-v3/testsuite/23_containers/forward_list/requirements/explicit_instantiation/alloc_ptr_ignored.cc
index 6205a2ff3bf2..19df931a6a65 100644
---
a/libstdc++-v3/testsuite/23_containers/forward_list/requirements/explicit_instantiation/alloc_ptr_ignored.cc
+++
b/libstdc++-v3/testsuite/23_containers/forward_list/requirements/explicit_instantiation/alloc_ptr_ignored.cc
@@ -1,4 +1,4 @@
-// { dg-options "-D_GLIBCXX_FWDLIST_USE_ALLOC_PTR=0" }
+// { dg-options "-D_GLIBCXX_USE_ALLOC_PTR_FOR_FWD_LIST=0" }
// { dg-do compile { target c++11 } }
#include "alloc_ptr.cc"
diff --git
a/libstdc++-v3/testsuite/23_containers/list/requirements/explicit_instantiation/alloc_ptr.cc
b/libstdc++-v3/testsuite/23_containers/list/requirements/explicit_instantiation/alloc_ptr.cc
index d3b2cfe6d923..c52591b3cf8b 100644
---
a/libstdc++-v3/testsuite/23_containers/list/requirements/explicit_instantiation/alloc_ptr.cc
+++
b/libstdc++-v3/testsuite/23_containers/list/requirements/explicit_instantiation/alloc_ptr.cc
@@ -57,6 +57,17 @@ struct Allocator
template class std::list<int, Allocator<int>>;
+struct NonTrivial
+{
+ NonTrivial() { }
+ NonTrivial(const NonTrivial&) { }
+ ~NonTrivial() { }
+ bool operator==(const NonTrivial&) const { return true; } // for remove(T)
+ bool operator<(const NonTrivial&) const { return false; } // for sort()
+};
+
+template class std::list<NonTrivial, Allocator<NonTrivial>>;
+
#include <testsuite_iterators.h>
void
diff --git
a/libstdc++-v3/testsuite/23_containers/list/requirements/explicit_instantiation/alloc_ptr_ignored.cc
b/libstdc++-v3/testsuite/23_containers/list/requirements/explicit_instantiation/alloc_ptr_ignored.cc
index e6a499d27160..f5bbf2cb944e 100644
---
a/libstdc++-v3/testsuite/23_containers/list/requirements/explicit_instantiation/alloc_ptr_ignored.cc
+++
b/libstdc++-v3/testsuite/23_containers/list/requirements/explicit_instantiation/alloc_ptr_ignored.cc
@@ -1,4 +1,4 @@
-// { dg-options "-D_GLIBCXX_LIST_USE_ALLOC_PTR=0" }
+// { dg-options "-D_GLIBCXX_USE_ALLOC_PTR_FOR_LIST=0" }
// { dg-do compile { target c++11 } }
#include "alloc_ptr.cc"
