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From: Jonathan Wakely <redi@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r13-8569] libstdc++: Constrain std::vector default constructor [PR113841] Date: Wed, 3 Apr 2024 10:46:44 +0000 (GMT) [thread overview] Message-ID: <20240403104644.625FA3846426@sourceware.org> (raw) https://gcc.gnu.org/g:87ec5b369eed205dfe6802afaaec3986b246ade9 commit r13-8569-g87ec5b369eed205dfe6802afaaec3986b246ade9 Author: Jonathan Wakely <jwakely@redhat.com> Date: Fri Feb 9 17:06:20 2024 +0000 libstdc++: Constrain std::vector default constructor [PR113841] This is needed to avoid errors outside the immediate context when evaluating is_default_constructible_v<vector<T, A>> when A is not default constructible. To avoid diagnostic regressions for 23_containers/vector/48101_neg.cc we need to make the std::allocator<cv T> partial specializations default constructible, which they probably should have been anyway. libstdc++-v3/ChangeLog: PR libstdc++/113841 * include/bits/allocator.h (allocator<cv T>): Add default constructor to partial specializations for cv-qualified types. * include/bits/stl_vector.h (_Vector_impl::_Vector_impl()): Constrain so that it's only present if the allocator is default constructible. * include/bits/stl_bvector.h (_Bvector_impl::_Bvector_impl()): Likewise. * testsuite/23_containers/vector/cons/113841.cc: New test. (cherry picked from commit 142cc4c223d695e515ed2504501b91d8a7ac6eb8) Diff: --- libstdc++-v3/include/bits/allocator.h | 3 ++ libstdc++-v3/include/bits/stl_bvector.h | 3 ++ libstdc++-v3/include/bits/stl_vector.h | 3 ++ .../testsuite/23_containers/vector/cons/113841.cc | 34 ++++++++++++++++++++++ 4 files changed, 43 insertions(+) diff --git a/libstdc++-v3/include/bits/allocator.h b/libstdc++-v3/include/bits/allocator.h index abbd753d33d..27e47521fe0 100644 --- a/libstdc++-v3/include/bits/allocator.h +++ b/libstdc++-v3/include/bits/allocator.h @@ -256,6 +256,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { public: typedef _Tp value_type; + allocator() { } template<typename _Up> allocator(const allocator<_Up>&) { } }; @@ -264,6 +265,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { public: typedef _Tp value_type; + allocator() { } template<typename _Up> allocator(const allocator<_Up>&) { } }; @@ -272,6 +274,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { public: typedef _Tp value_type; + allocator() { } template<typename _Up> allocator(const allocator<_Up>&) { } }; /// @endcond diff --git a/libstdc++-v3/include/bits/stl_bvector.h b/libstdc++-v3/include/bits/stl_bvector.h index 8b54292e51b..e18de7c62aa 100644 --- a/libstdc++-v3/include/bits/stl_bvector.h +++ b/libstdc++-v3/include/bits/stl_bvector.h @@ -593,6 +593,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER _GLIBCXX20_CONSTEXPR _Bvector_impl() _GLIBCXX_NOEXCEPT_IF( is_nothrow_default_constructible<_Bit_alloc_type>::value) +#if __cpp_concepts + requires is_default_constructible_v<_Bit_alloc_type> +#endif : _Bit_alloc_type() { } diff --git a/libstdc++-v3/include/bits/stl_vector.h b/libstdc++-v3/include/bits/stl_vector.h index acb29396d26..798e66d91ac 100644 --- a/libstdc++-v3/include/bits/stl_vector.h +++ b/libstdc++-v3/include/bits/stl_vector.h @@ -136,6 +136,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER _GLIBCXX20_CONSTEXPR _Vector_impl() _GLIBCXX_NOEXCEPT_IF( is_nothrow_default_constructible<_Tp_alloc_type>::value) +#if __cpp_lib_concepts + requires is_default_constructible_v<_Tp_alloc_type> +#endif : _Tp_alloc_type() { } diff --git a/libstdc++-v3/testsuite/23_containers/vector/cons/113841.cc b/libstdc++-v3/testsuite/23_containers/vector/cons/113841.cc new file mode 100644 index 00000000000..a7721d27f79 --- /dev/null +++ b/libstdc++-v3/testsuite/23_containers/vector/cons/113841.cc @@ -0,0 +1,34 @@ +// { dg-do compile { target c++20 } } + +#include <vector> + +template<typename T> +struct Alloc +{ + using value_type = T; + + Alloc(int) { } // not default constructible + + template<typename U> Alloc(const Alloc<U>&) { } + + T* allocate(std::size_t n) { return std::allocator<T>().allocate(n); } + void deallocate(T* p, std::size_t n) { std::allocator<T>().deallocate(p, n); } +}; + +template<typename T> struct wrap { T t; }; + +template<typename T> void do_adl(T&) { } + +void test_pr113841() +{ + using test_type = std::vector<int, Alloc<int>>; + std::pair<const int, wrap<test_type>>* h = nullptr; + do_adl(h); +} + +void test_pr113841_bool() +{ + using test_type = std::vector<bool, Alloc<bool>>; + std::pair<const int, wrap<test_type>>* h = nullptr; + do_adl(h); +}
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