https://gcc.gnu.org/g:e38acbc88bfede15884009330ab75debb114905d
commit r17-809-ge38acbc88bfede15884009330ab75debb114905d Author: Tomasz Kamiński <[email protected]> Date: Fri Apr 24 05:26:06 2026 +0200 libstdc++: static_assert that static sized range size is less than inplace_vector capacity Resolves LWG 4396. Improve inplace_vector(from_range_t, R&& rg) The test case illustrates that views applied to span<T, N> are still statically sized, but once applied to array<T, N> are not. This is caused by the fact that ref_view stores a pointer to array, and dereference of unknown pointers does not produce reference to unknown, and simply yield non-constant expressions (unknown pointer is not equivalent to pointer to unknown, as it may be null). libstdc++-v3/ChangeLog: * include/std/inplace_vector (inplace_vector(std::from_range, __Rg&&)): Add static_asserts checking range size. * testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc: New test. * testsuite/23_containers/inplace_vector/cons/from_range_neg.cc: New test. Reviewed-by: Jonathan Wakely <[email protected]> Reviewed-by: Patrick Palka <[email protected]> Signed-off-by: Tomasz Kamiński <[email protected]> Diff: --- libstdc++-v3/include/std/inplace_vector | 16 ++++- .../inplace_vector/cons/from_iota_neg.cc | 46 +++++++++++++ .../inplace_vector/cons/from_range_neg.cc | 78 ++++++++++++++++++++++ 3 files changed, 138 insertions(+), 2 deletions(-) diff --git a/libstdc++-v3/include/std/inplace_vector b/libstdc++-v3/include/std/inplace_vector index 0096bd83a175..caf9c2032452 100644 --- a/libstdc++-v3/include/std/inplace_vector +++ b/libstdc++-v3/include/std/inplace_vector @@ -41,7 +41,7 @@ #include <optional> #include <bits/stdexcept_throw.h> #include <bits/range_access.h> -#include <bits/ranges_base.h> // borrowed_iterator_t, __detail::__container_compatible_range +#include <bits/ranges_base.h> // borrowed_iterator_t, __detail::__container_compatible_range, __static_sized_range #include <bits/ranges_util.h> // subrange #include <bits/ranges_uninitialized.h> #include <bits/stl_construct.h> @@ -120,7 +120,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER constexpr inplace_vector(from_range_t, _Rg&& __rg) : inplace_vector() - { append_range(__rg); } + { + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 4396. Improve inplace_vector(from_range_t, R&& rg) + if constexpr (ranges::__static_sized_range<_Rg>) + static_assert(ranges::size(__rg) <= _Nm); + + append_range(__rg); + } constexpr inplace_vector(initializer_list<_Tp> __il) @@ -934,6 +941,11 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER constexpr inplace_vector(from_range_t, _Rg&& __rg) { + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 4396. Improve inplace_vector(from_range_t, R&& rg) + if constexpr (ranges::__static_sized_range<_Rg>) + static_assert(ranges::size(__rg) == 0); + if (ranges::begin(__rg) != ranges::end(__rg)) __throw_bad_alloc(); } diff --git a/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc b/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc new file mode 100644 index 000000000000..ae0b96175b7d --- /dev/null +++ b/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc @@ -0,0 +1,46 @@ +// { dg-do compile { target c++26 } } +// { dg-require-effective-target int128 } + +#include <array> +#include <ranges> +#include <span> +#include <inplace_vector> + +template<typename Int, Int min, Int max = std::numeric_limits<Int>::max()> +struct StaticIota : std::ranges::iota_view<Int, Int> +{ + using Base = std::ranges::iota_view<Int, Int>; + using size_type = std::ranges::range_size_t<Base>; + + constexpr StaticIota() noexcept : Base(min, max) {} + + constexpr static size_type + size() + { return size_type(max) - size_type(min); } +}; + +template<typename Range> +constexpr std::ranges::ref_view<Range> +ref_view(Range& rg) +{ return std::ranges::ref_view<Range>(rg); } + +void +test_all() +{ + StaticIota<__int128, 0, 12> m12; + + std::inplace_vector<int, 15> tm1(std::from_range, m12); + std::inplace_vector<int, 15> tr1(std::from_range, ref_view(m12)); + + std::inplace_vector<int, 10> tm2(std::from_range, m12); // { dg-error "(from here|expansion of)" } + // ref_view is not statically sized due pointer dereference + std::inplace_vector<int, 10> tr2(std::from_range, ref_view(m12)); + + StaticIota<__int128, 0> mm; + + std::inplace_vector<int, 10> tm3(std::from_range, mm); // { dg-error "(from here|expansion of)" } + // ref_view is not statically sized due pointer dereference + std::inplace_vector<int, 10> tr3(std::from_range, ref_view(mm)); +} + +// { dg-error "static assertion failed" "" { target *-*-* } 0 } diff --git a/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_range_neg.cc b/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_range_neg.cc new file mode 100644 index 000000000000..48d5b4c56f59 --- /dev/null +++ b/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_range_neg.cc @@ -0,0 +1,78 @@ +// { dg-do compile { target c++26 } } + +#include <array> +#include <ranges> +#include <span> +#include <inplace_vector> + +template<typename Range0> +void +test_zero(Range0&& r0) +{ + std::inplace_vector<int, 0> f0(std::from_range, r0); + std::inplace_vector<int, 1> f1(std::from_range, r0); + std::inplace_vector<int, 5> f5(std::from_range, r0); + std::inplace_vector<int, 7> f7(std::from_range, r0); +} + +template<typename Range1> +void +test_one(Range1&& r1) +{ + std::inplace_vector<int, 0> f0(std::from_range, r1); // { dg-error "required from" } + std::inplace_vector<int, 1> f1(std::from_range, r1); + std::inplace_vector<int, 5> f5(std::from_range, r1); + std::inplace_vector<int, 7> f7(std::from_range, r1); +} + +template<typename Range5> +void +test_five(Range5&& r5) +{ + std::inplace_vector<int, 0> f0(std::from_range, r5); // { dg-error "required from" } + std::inplace_vector<int, 1> f1(std::from_range, r5); // { dg-error "required from" } + std::inplace_vector<int, 3> f3(std::from_range, r5); // { dg-error "required from" } + std::inplace_vector<int, 5> f5(std::from_range, r5); + std::inplace_vector<int, 7> f7(std::from_range, r5); +} + +template<typename Range> +constexpr std::ranges::ref_view<Range> +ref_view(Range& rg) +{ return std::ranges::ref_view<Range>(rg); } + +void +test_all() +{ + std::array<int, 0> a0; + std::span<int, 0> s0(a0); + std::array<int, 1> a1; + std::span<int, 1> s1(a1); + std::array<int, 5> a5; + std::span<int, 5> s5(a5); + std::array<int, 7> a7; + std::span<int, 7> s7(a7); + + test_zero(a0); + test_zero(s0); + test_zero(ref_view(a0)); + test_zero(std::views::empty<int>); + test_zero(s5 | std::views::adjacent<7> | std::views::elements<0>); + test_zero(a5 | std::views::adjacent<7> | std::views::elements<0>); + + test_one(a1); // { dg-error "from here" } + test_one(s1); // { dg-error "from here" } + // ref_view is not statically sized due pointer dereference + test_one(ref_view(a1)); + test_one(a5 | std::views::adjacent<7> | std::views::elements<0>); + test_one(s5 | std::views::adjacent<5> | std::views::elements<0>); // { dg-error "from here" } + + test_five(a5); // { dg-error "from here" } + test_five(s5); // { dg-error "from here" } + // ref_view is not statically sized due pointer dereference + test_five(ref_view(a5)); + test_five(a7 | std::views::adjacent<3> | std::views::elements<0>); + test_five(s7 | std::views::adjacent<3> | std::views::elements<0>); // { dg-error "from here" } +} + +// { dg-error "static assertion failed" "" { target *-*-* } 0 }
