On 7/28/25 10:15, Tomasz Kaminski wrote:
On Sun, Jul 27, 2025 at 3:38 PM Luc Grosheintz <luc.groshei...@gmail.com> wrote:Versions 1, 2 and 3 of the patch for adding aligned_accessor had a bug in the constraints that allowed conversion of aligned_accessor<T, N> a = aligned_accessor<const T, N>{}; and prevented the reverse. The file mdspan/accessors/generic.cc already contains code that checks all variation of the constraint. This commit allows passing in two different accessors. Enabling it to be reused more widely. libstdc++-v3/ChangeLog: * testsuite/23_containers/mdspan/accessors/generic.cc: Refactor test_ctor. Signed-off-by: Luc Grosheintz <luc.groshei...@gmail.com> ---LGTM, with one note about duplicated assertions. I will remove it locally, and push the commit..../23_containers/mdspan/accessors/generic.cc | 61 ++++++++++++------- 1 file changed, 39 insertions(+), 22 deletions(-) diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/accessors/generic.cc b/libstdc++-v3/testsuite/23_containers/mdspan/accessors/generic.cc index c3350353aae..70c3bd0751c 100644 --- a/libstdc++-v3/testsuite/23_containers/mdspan/accessors/generic.cc +++ b/libstdc++-v3/testsuite/23_containers/mdspan/accessors/generic.cc @@ -29,44 +29,61 @@ class Base class Derived : public Base { }; -template<template<typename T> typename Accessor> +template<typename RhsAccessor, typename LhsAccessor, bool ExpectConvertible> + constexpr void + check_convertible() + { + RhsAccessor rhs; + [[maybe_unused]] LhsAccessor lhs(rhs); + static_assert(std::is_nothrow_constructible_v<LhsAccessor, RhsAccessor>); + static_assert(std::is_convertible_v<RhsAccessor, LhsAccessor> == ExpectConvertible); + } + +template<template<typename T> typename LhsAccessor, + template<typename T> typename RhsAccessor = LhsAccessor, + bool ExpectConvertible = true> constexpr bool test_ctor() { // T -> T - static_assert(std::is_nothrow_constructible_v<Accessor<double>, - Accessor<double>>); - static_assert(std::is_convertible_v<Accessor<double>, Accessor<double>>); + static_assert(std::is_nothrow_constructible_v<LhsAccessor<double>, + RhsAccessor<double>>);This static assert seems to be redundant to one in check_convertible, so I will remove it and the push th changes.
Indeed, nicely spotted!
+ check_convertible<RhsAccessor<double>, LhsAccessor<double>, + ExpectConvertible>(); // T -> const T - static_assert(std::is_convertible_v<Accessor<double>, - Accessor<const double>>); - static_assert(std::is_convertible_v<Accessor<Derived>, - Accessor<const Derived>>); + check_convertible<RhsAccessor<double>, LhsAccessor<const double>, + ExpectConvertible>(); + check_convertible<RhsAccessor<Derived>, LhsAccessor<const Derived>, + ExpectConvertible>(); // const T -> T - static_assert(!std::is_constructible_v<Accessor<double>, - Accessor<const double>>); - static_assert(!std::is_constructible_v<Accessor<Derived>, - Accessor<const Derived>>); + static_assert(!std::is_constructible_v<LhsAccessor<double>, + RhsAccessor<const double>>); + static_assert(!std::is_constructible_v<LhsAccessor<Derived>, + RhsAccessor<const Derived>>); // T <-> volatile T - static_assert(std::is_convertible_v<Accessor<int>, Accessor<volatile int>>); - static_assert(!std::is_constructible_v<Accessor<int>, - Accessor<volatile int>>); + check_convertible<RhsAccessor<int>, LhsAccessor<volatile int>, + ExpectConvertible>(); + static_assert(!std::is_constructible_v<LhsAccessor<int>, + RhsAccessor<volatile int>>); // size difference - static_assert(!std::is_constructible_v<Accessor<char>, Accessor<int>>); + static_assert(!std::is_constructible_v<LhsAccessor<char>, + RhsAccessor<int>>); // signedness - static_assert(!std::is_constructible_v<Accessor<int>, - Accessor<unsigned int>>); - static_assert(!std::is_constructible_v<Accessor<unsigned int>, - Accessor<int>>); + static_assert(!std::is_constructible_v<LhsAccessor<int>, + RhsAccessor<unsigned int>>); + static_assert(!std::is_constructible_v<LhsAccessor<unsigned int>, + RhsAccessor<int>>); // Derived <-> Base - static_assert(!std::is_constructible_v<Accessor<Base>, Accessor<Derived>>); - static_assert(!std::is_constructible_v<Accessor<Derived>, Accessor<Base>>); + static_assert(!std::is_constructible_v<LhsAccessor<Base>, + RhsAccessor<Derived>>); + static_assert(!std::is_constructible_v<LhsAccessor<Derived>, + RhsAccessor<Base>>); return true; } -- 2.50.0
