https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57272
--- Comment #11 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Francois Dumont <fdum...@gcc.gnu.org>: https://gcc.gnu.org/g:23df3c3a4aa33a08e82ac8b98d7ff6e7f1b65b63 commit r15-6376-g23df3c3a4aa33a08e82ac8b98d7ff6e7f1b65b63 Author: François Dumont <frs.dum...@gmail.com> Date: Mon Jul 22 21:54:36 2024 +0200 libstdc++: Add fancy pointer support to std::map and std::set [PR57272] The fancy allocator pointer type support is added to std::map, std::multimap, std::multiset and std::set through the underlying std::_Rb_tree class. To respect ABI a new parralel hierarchy of node types has been added. This change introduces new class template parameterized on the allocator's void_pointer type, __rb_tree::_Node_base, and new class templates parameterized on the allocator's pointer type, __rb_tree::_Node, __rb_tree::_Iterator. The iterator class template is used for both iterator and const_iterator. Whether std::_Rb_tree<K, V, KoV, C, A> should use the old _Rb_tree_node<V> or new __rb_tree::_Node<A::pointer> type family internally is controlled by a new __rb_tree::_Node_traits traits template. Because std::pointer_traits and std::__to_address are not defined for C++98, there is no way to support fancy pointers in C++98. For C++98 the _Node_traits traits always choose the old _Rb_tree_node family. In case anybody is currently using std::_Rb_tree with an allocator that has a fancy pointer, this change would be an ABI break, because their std::_Rb_tree instantiations would start to (correctly) use the fancy pointer type. If the fancy pointer just contains a single pointer and so has the same size, layout, and object representation as a raw pointer, the code might still work (despite being an ODR violation). But if their fancy pointer has a different representation, they would need to recompile all their code using that allocator with std::_Rb_tree. Because std::_Rb_tree will never use fancy pointers in C++98 mode, recompiling everything to use fancy pointers isn't even possible if mixing C++98 and C++11 code that uses std::_Rb_tree. To alleviate this problem, compiling with -D_GLIBCXX_USE_ALLOC_PTR_FOR_RB_TREE=0 will force std::_Rb_tree to have the old, non-conforming behaviour and use raw pointers internally. For testing purposes, compiling with -D_GLIBCXX_USE_ALLOC_PTR_FOR_RB_TREE=9001 will force std::_Rb_tree to always use the new node types. This macro is currently undocumented, which needs to be fixed. As _Rb_tree is using _Base_ptr to represent the tree this change also simplifies the implementation by removing all the const pointer types and associated methods. libstdc++-v3/ChangeLog: PR libstdc++/57272 * include/bits/stl_tree.h [_GLIBCXX_USE_ALLOC_PTR_FOR_RB_TREE]: New macro to control usage of the code required to support fancy allocator pointer type. (_Rb_tree_node_base::_Const_Base_ptr): Remove. (_Rb_tree_node_base::_S_minimum, _Rb_tree_node_base::_S_maximum): Remove overloads for _Const_Base_ptr. (_Rb_tree_node_base::_M_base_ptr()): New. (_Rb_tree_node::_Link_type): Remove. (_Rb_tree_node::_M_node_ptr()): New. (__rb_tree::_Node_base<>): New. (__rb_tree::_Header<>): New. (__rb_tree::_Node<>): New. (_Rb_tree_increment(const _Rb_tree_node_base*)): Remove declaration. (_Rb_tree_decrement(const _Rb_tree_node_base*)): Remove declaration. (_Rb_tree_iterator<>::_Self): Remove. (_Rb_tree_iterator<>::_Link_type): Rename into... (_Rb_tree_iterator<>::_Node_ptr): ...this. (_Rb_tree_const_iterator<>::_Link_type): Rename into... (_Rb_tree_const_iterator<>::_Node_ptr): ...this. (_Rb_tree_const_iterator<>::_M_const_cast): Remove. (_Rb_tree_const_iterator<>::_M_node): Change type into _Base_ptr. (__rb_tree::_Iterator<>): New. (__rb_tree::_Node_traits<>): New. (_Rb_tree<>::_Node_base, _Rb_tree::_Node): New. (_Rb_tree<>::_Link_type): Rename into... (_Rb_tree<>::_Node_ptr): ...this. (_Rb_tree<>::_Const_Base_ptr, _Rb_tree<>::_Const_Node_ptr): Remove. (_Rb_tree<>::_M_mbegin): Remove. (_Rb_tree<>::_M_begin_node()): New. (_S_key(const _Node&)): New. (_S_key(_Base_ptr)): New, call latter. (_S_key(_Node_ptr)): Likewise. (_Rb_tree<>::_S_left(_Const_Base_ptr)): Remove. (_Rb_tree<>::_S_right(_Const_Base_ptr)): Remove. (_Rb_tree<>::_S_maximum(_Const_Base_ptr)): Remove. (_Rb_tree<>::_S_minimum(_Const_Base_ptr)): Remove. * testsuite/23_containers/map/allocator/ext_ptr.cc: New test case. * testsuite/23_containers/multimap/allocator/ext_ptr.cc: New test case. * testsuite/23_containers/multiset/allocator/ext_ptr.cc: New test case. * testsuite/23_containers/set/allocator/ext_ptr.cc: New test case. * testsuite/23_containers/set/requirements/explicit_instantiation/alloc_ptr.cc: New test case. * testsuite/23_containers/set/requirements/explicit_instantiation/alloc_ptr_ignored.cc: New test case.
