https://gcc.gnu.org/g:4598d7fcbde6dd87274a91a247134ba3c12be0cd
commit r17-807-g4598d7fcbde6dd87274a91a247134ba3c12be0cd Author: Jonathan Wakely <[email protected]> Date: Thu May 21 18:58:14 2026 +0100 libstdc++: Add missing constraints to vector and deque deduction guides The standard requires that these deduction guides are constrained to only accept a type that qualifies as an allocator for the second templates argument. libstdc++-v3/ChangeLog: * include/bits/stl_deque.h: Add missing constraint on allocator type in deduction guide. * include/bits/stl_vector.h: Likewise. * include/debug/deque: Likewise. * include/debug/vector: Likewise. * testsuite/23_containers/deque/cons/deduction_c++23.cc: Check that deduction fails for a type which does not qualify as an allocator. * testsuite/23_containers/vector/cons/deduction_c++23.cc: Likewise. Reviewed-by: Tomasz Kamiński <[email protected]> Diff: --- libstdc++-v3/include/bits/stl_deque.h | 2 +- libstdc++-v3/include/bits/stl_vector.h | 2 +- libstdc++-v3/include/debug/deque | 2 +- libstdc++-v3/include/debug/vector | 2 +- .../testsuite/23_containers/deque/cons/deduction_c++23.cc | 14 ++++++++++++++ .../testsuite/23_containers/vector/cons/deduction_c++23.cc | 14 ++++++++++++++ 6 files changed, 32 insertions(+), 4 deletions(-) diff --git a/libstdc++-v3/include/bits/stl_deque.h b/libstdc++-v3/include/bits/stl_deque.h index aebe865ffc1a..28f61d2ccd37 100644 --- a/libstdc++-v3/include/bits/stl_deque.h +++ b/libstdc++-v3/include/bits/stl_deque.h @@ -2414,7 +2414,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER #if __glibcxx_containers_ranges // C++ >= 23 template<ranges::input_range _Rg, - typename _Alloc = allocator<ranges::range_value_t<_Rg>>> + __allocator_like _Alloc = allocator<ranges::range_value_t<_Rg>>> deque(from_range_t, _Rg&&, _Alloc = _Alloc()) -> deque<ranges::range_value_t<_Rg>, _Alloc>; #endif diff --git a/libstdc++-v3/include/bits/stl_vector.h b/libstdc++-v3/include/bits/stl_vector.h index 0c9b74fdbb24..9ddf35502e69 100644 --- a/libstdc++-v3/include/bits/stl_vector.h +++ b/libstdc++-v3/include/bits/stl_vector.h @@ -2383,7 +2383,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER #if __glibcxx_containers_ranges // C++ >= 23 template<ranges::input_range _Rg, - typename _Alloc = allocator<ranges::range_value_t<_Rg>>> + __allocator_like _Alloc = allocator<ranges::range_value_t<_Rg>>> vector(from_range_t, _Rg&&, _Alloc = _Alloc()) -> vector<ranges::range_value_t<_Rg>, _Alloc>; #endif diff --git a/libstdc++-v3/include/debug/deque b/libstdc++-v3/include/debug/deque index 9fba4ffc4997..00b4220051e7 100644 --- a/libstdc++-v3/include/debug/deque +++ b/libstdc++-v3/include/debug/deque @@ -715,7 +715,7 @@ namespace __debug #if __glibcxx_containers_ranges // C++ >= 23 template<ranges::input_range _Rg, - typename _Alloc = allocator<ranges::range_value_t<_Rg>>> + __allocator_like _Alloc = allocator<ranges::range_value_t<_Rg>>> deque(from_range_t, _Rg&&, _Alloc = _Alloc()) -> deque<ranges::range_value_t<_Rg>, _Alloc>; #endif diff --git a/libstdc++-v3/include/debug/vector b/libstdc++-v3/include/debug/vector index 61e5ff78a7a4..56645d1e92c3 100644 --- a/libstdc++-v3/include/debug/vector +++ b/libstdc++-v3/include/debug/vector @@ -1001,7 +1001,7 @@ namespace __debug #if __glibcxx_containers_ranges // C++ >= 23 template<ranges::input_range _Rg, - typename _Alloc = allocator<ranges::range_value_t<_Rg>>> + __allocator_like _Alloc = allocator<ranges::range_value_t<_Rg>>> vector(from_range_t, _Rg&&, _Alloc = _Alloc()) -> vector<ranges::range_value_t<_Rg>, _Alloc>; #endif diff --git a/libstdc++-v3/testsuite/23_containers/deque/cons/deduction_c++23.cc b/libstdc++-v3/testsuite/23_containers/deque/cons/deduction_c++23.cc new file mode 100644 index 000000000000..5893de92dc6f --- /dev/null +++ b/libstdc++-v3/testsuite/23_containers/deque/cons/deduction_c++23.cc @@ -0,0 +1,14 @@ +// { dg-do compile { target c++23 } } + +#include <deque> +#include <testsuite_iterators.h> + +using Range = __gnu_test::test_input_range<int>; + +template<typename Alloc> +concept can_deduce_deque = requires(Range r, Alloc a) { + std::deque(std::from_range, r, a); +}; + +// Deduction should fail because int does not qualify as an allocator. +static_assert( ! can_deduce_deque<int> ); diff --git a/libstdc++-v3/testsuite/23_containers/vector/cons/deduction_c++23.cc b/libstdc++-v3/testsuite/23_containers/vector/cons/deduction_c++23.cc new file mode 100644 index 000000000000..1a442a8ed5c2 --- /dev/null +++ b/libstdc++-v3/testsuite/23_containers/vector/cons/deduction_c++23.cc @@ -0,0 +1,14 @@ +// { dg-do compile { target c++23 } } + +#include <vector> +#include <testsuite_iterators.h> + +using Range = __gnu_test::test_input_range<int>; + +template<typename Alloc> +concept can_deduce_vector = requires(Range r, Alloc a) { + std::vector(std::from_range, r, a); +}; + +// Deduction should fail because int does not qualify as an allocator. +static_assert( ! can_deduce_vector<int> );
