commit 82626be2d633a9802a8b08727ef51c627e37fee5 Author: Jonathan Wakely Date: Tue Sep 28 15:26:46 2021 libstdc++: Specialize std::pointer_traits<__normal_iterator> This allows std::__to_address to be used with __normal_iterator in C++11/14/17 modes. Without the partial specialization the deduced pointer_traits::element_type is incorrect, and so the return type of __to_address is wrong. A similar partial specialization is probably needed for __gnu_debug::_Safe_iterator. Signed-off-by: Jonathan Wakely libstdc++-v3/ChangeLog: * include/bits/stl_iterator.h (pointer_traits): Define partial specialization for __normal_iterator. * testsuite/24_iterators/normal_iterator/to_address.cc: New test. diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h index c5b02408c1c..004d767224d 100644 --- a/libstdc++-v3/include/bits/stl_iterator.h +++ b/libstdc++-v3/include/bits/stl_iterator.h @@ -1285,6 +1285,34 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { return __it.base(); } #if __cplusplus >= 201103L + + // Need to specialize pointer_traits because the primary template will + // deduce element_type of __normal_iterator as T* rather than T. + template + struct pointer_traits<__gnu_cxx::__normal_iterator<_Iterator, _Container>> + { + private: + using _Base = pointer_traits<_Iterator>; + + public: + using element_type = typename _Base::element_type; + using pointer = __gnu_cxx::__normal_iterator<_Iterator, _Container>; + using difference_type = typename _Base::difference_type; + + template + using rebind = __gnu_cxx::__normal_iterator<_Tp, _Container>; + + static pointer + pointer_to(element_type& __e) noexcept + { return pointer(_Base::pointer_to(__e)); } + +#if __cplusplus >= 202002L + static element_type* + to_address(pointer __p) noexcept + { return __p.base(); } +#endif + }; + /** * @addtogroup iterators * @{ diff --git a/libstdc++-v3/testsuite/24_iterators/normal_iterator/to_address.cc b/libstdc++-v3/testsuite/24_iterators/normal_iterator/to_address.cc new file mode 100644 index 00000000000..510d627435f --- /dev/null +++ b/libstdc++-v3/testsuite/24_iterators/normal_iterator/to_address.cc @@ -0,0 +1,6 @@ +// { dg-do compile { target { c++11 } } } +#include +#include + +char* p = std::__to_address(std::string("1").begin()); +const char* q = std::__to_address(std::string("2").cbegin());