[libcxx-commits] [libcxx] [libc++][array] Applied `[[nodiscard]]` (PR #168829)
Hristo Hristov via libcxx-commits
libcxx-commits at lists.llvm.org
Fri Nov 21 18:54:45 PST 2025
https://github.com/Zingam updated https://github.com/llvm/llvm-project/pull/168829
>From 5cbfae59f378a9eaa98ea834c2e8e1be521be9eb Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Thu, 20 Nov 2025 07:59:03 +0200
Subject: [PATCH 1/7] [libc++][array] Applied `[[nodiscard]]``
`[[nodiscard]]` should be applied to functions where discarding the return value is most likely a correctness issue.
- https://libcxx.llvm.org/CodingGuidelines.html#apply-nodiscard-where-relevant
---
libcxx/include/array | 145 +++++++++++-------
.../diagnostics/array.nodiscard.verify.cpp | 91 ++++++++++-
.../array/array.creation/to_array.verify.cpp | 20 ++-
3 files changed, 188 insertions(+), 68 deletions(-)
diff --git a/libcxx/include/array b/libcxx/include/array
index ff46838e2e8e2..d346b50cfcd7a 100644
--- a/libcxx/include/array
+++ b/libcxx/include/array
@@ -210,28 +210,28 @@ struct array {
}
// iterators:
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 iterator begin() _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 iterator begin() _NOEXCEPT {
# if defined(_LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY)
return std::__make_static_bounded_iter<_Size>(data(), data());
# else
return iterator(data());
# endif
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator begin() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator begin() const _NOEXCEPT {
# if defined(_LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY)
return std::__make_static_bounded_iter<_Size>(data(), data());
# else
return const_iterator(data());
# endif
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 iterator end() _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 iterator end() _NOEXCEPT {
# if defined(_LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY)
return std::__make_static_bounded_iter<_Size>(data() + _Size, data());
# else
return iterator(data() + _Size);
# endif
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator end() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator end() const _NOEXCEPT {
# if defined(_LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY)
return std::__make_static_bounded_iter<_Size>(data() + _Size, data());
# else
@@ -239,62 +239,81 @@ struct array {
# endif
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reverse_iterator rbegin() _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reverse_iterator rbegin() _NOEXCEPT {
return reverse_iterator(end());
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator rbegin() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator
+ rbegin() const _NOEXCEPT {
return const_reverse_iterator(end());
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reverse_iterator rend() _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reverse_iterator rend() _NOEXCEPT {
return reverse_iterator(begin());
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator rend() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator rend() const _NOEXCEPT {
return const_reverse_iterator(begin());
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator cbegin() const _NOEXCEPT { return begin(); }
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator cend() const _NOEXCEPT { return end(); }
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator crbegin() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator cbegin() const _NOEXCEPT {
+ return begin();
+ }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator cend() const _NOEXCEPT {
+ return end();
+ }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator
+ crbegin() const _NOEXCEPT {
return rbegin();
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator crend() const _NOEXCEPT { return rend(); }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator crend() const _NOEXCEPT {
+ return rend();
+ }
// capacity:
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR size_type size() const _NOEXCEPT { return _Size; }
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR size_type max_size() const _NOEXCEPT { return _Size; }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR size_type size() const _NOEXCEPT { return _Size; }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR size_type max_size() const _NOEXCEPT { return _Size; }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool empty() const _NOEXCEPT { return _Size == 0; }
// element access:
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference operator[](size_type __n) _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference operator[](size_type __n) _NOEXCEPT {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__n < _Size, "out-of-bounds access in std::array<T, N>");
return __elems_[__n];
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference operator[](size_type __n) const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference
+ operator[](size_type __n) const _NOEXCEPT {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__n < _Size, "out-of-bounds access in std::array<T, N>");
return __elems_[__n];
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference at(size_type __n) {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference at(size_type __n) {
if (__n >= _Size)
std::__throw_out_of_range("array::at");
return __elems_[__n];
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference at(size_type __n) const {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference at(size_type __n) const {
if (__n >= _Size)
std::__throw_out_of_range("array::at");
return __elems_[__n];
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference front() _NOEXCEPT { return (*this)[0]; }
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference front() const _NOEXCEPT { return (*this)[0]; }
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference back() _NOEXCEPT { return (*this)[_Size - 1]; }
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference back() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference front() _NOEXCEPT {
+ return (*this)[0];
+ }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference front() const _NOEXCEPT {
+ return (*this)[0];
+ }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference back() _NOEXCEPT {
+ return (*this)[_Size - 1];
+ }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference back() const _NOEXCEPT {
return (*this)[_Size - 1];
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 value_type* data() _NOEXCEPT { return __elems_; }
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const value_type* data() const _NOEXCEPT { return __elems_; }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 value_type* data() _NOEXCEPT {
+ return __elems_;
+ }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const value_type* data() const _NOEXCEPT {
+ return __elems_;
+ }
};
template <class _Tp>
@@ -328,8 +347,10 @@ struct array<_Tp, 0> {
};
_ALIGNAS_TYPE(_ArrayInStructT) _EmptyType __elems_[sizeof(_ArrayInStructT)];
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 value_type* data() _NOEXCEPT { return nullptr; }
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const value_type* data() const _NOEXCEPT { return nullptr; }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 value_type* data() _NOEXCEPT { return nullptr; }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const value_type* data() const _NOEXCEPT {
+ return nullptr;
+ }
// No explicit construct/copy/destroy for aggregate type
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void fill(const value_type&) {
@@ -341,28 +362,28 @@ struct array<_Tp, 0> {
}
// iterators:
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 iterator begin() _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 iterator begin() _NOEXCEPT {
# if defined(_LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY)
return std::__make_static_bounded_iter<0>(data(), data());
# else
return iterator(data());
# endif
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator begin() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator begin() const _NOEXCEPT {
# if defined(_LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY)
return std::__make_static_bounded_iter<0>(data(), data());
# else
return const_iterator(data());
# endif
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 iterator end() _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 iterator end() _NOEXCEPT {
# if defined(_LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY)
return std::__make_static_bounded_iter<0>(data(), data());
# else
return iterator(data());
# endif
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator end() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator end() const _NOEXCEPT {
# if defined(_LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY)
return std::__make_static_bounded_iter<0>(data(), data());
# else
@@ -370,68 +391,77 @@ struct array<_Tp, 0> {
# endif
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reverse_iterator rbegin() _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reverse_iterator rbegin() _NOEXCEPT {
return reverse_iterator(end());
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator rbegin() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator
+ rbegin() const _NOEXCEPT {
return const_reverse_iterator(end());
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reverse_iterator rend() _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reverse_iterator rend() _NOEXCEPT {
return reverse_iterator(begin());
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator rend() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator rend() const _NOEXCEPT {
return const_reverse_iterator(begin());
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator cbegin() const _NOEXCEPT { return begin(); }
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator cend() const _NOEXCEPT { return end(); }
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator crbegin() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator cbegin() const _NOEXCEPT {
+ return begin();
+ }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_iterator cend() const _NOEXCEPT {
+ return end();
+ }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator
+ crbegin() const _NOEXCEPT {
return rbegin();
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator crend() const _NOEXCEPT { return rend(); }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 const_reverse_iterator crend() const _NOEXCEPT {
+ return rend();
+ }
// capacity:
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR size_type size() const _NOEXCEPT { return 0; }
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR size_type max_size() const _NOEXCEPT { return 0; }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR size_type size() const _NOEXCEPT { return 0; }
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR size_type max_size() const _NOEXCEPT { return 0; }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool empty() const _NOEXCEPT { return true; }
// element access:
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference operator[](size_type) _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference operator[](size_type) _NOEXCEPT {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(false, "cannot call array<T, 0>::operator[] on a zero-sized array");
__libcpp_unreachable();
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference operator[](size_type) const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference
+ operator[](size_type) const _NOEXCEPT {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(false, "cannot call array<T, 0>::operator[] on a zero-sized array");
__libcpp_unreachable();
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference at(size_type) {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference at(size_type) {
std::__throw_out_of_range("array<T, 0>::at");
__libcpp_unreachable();
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference at(size_type) const {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference at(size_type) const {
std::__throw_out_of_range("array<T, 0>::at");
__libcpp_unreachable();
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference front() _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference front() _NOEXCEPT {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(false, "cannot call array<T, 0>::front() on a zero-sized array");
__libcpp_unreachable();
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference front() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference front() const _NOEXCEPT {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(false, "cannot call array<T, 0>::front() on a zero-sized array");
__libcpp_unreachable();
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference back() _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 reference back() _NOEXCEPT {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(false, "cannot call array<T, 0>::back() on a zero-sized array");
__libcpp_unreachable();
}
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference back() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const_reference back() const _NOEXCEPT {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(false, "cannot call array<T, 0>::back() on a zero-sized array");
__libcpp_unreachable();
}
@@ -443,8 +473,8 @@ array(_Tp, _Args...) -> array<_Tp, 1 + sizeof...(_Args)>;
# endif
template <class _Tp, size_t _Size>
-inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
-operator==(const array<_Tp, _Size>& __x, const array<_Tp, _Size>& __y) {
+inline _LIBCPP_HIDE_FROM_ABI
+_LIBCPP_CONSTEXPR_SINCE_CXX20 bool operator==(const array<_Tp, _Size>& __x, const array<_Tp, _Size>& __y) {
return std::equal(__x.begin(), __x.end(), __y.begin());
}
@@ -501,25 +531,28 @@ struct tuple_element<_Ip, array<_Tp, _Size> > {
};
template <size_t _Ip, class _Tp, size_t _Size>
-inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp& get(array<_Tp, _Size>& __a) _NOEXCEPT {
+[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp&
+get(array<_Tp, _Size>& __a) _NOEXCEPT {
static_assert(_Ip < _Size, "Index out of bounds in std::get<> (std::array)");
return __a.__elems_[_Ip];
}
template <size_t _Ip, class _Tp, size_t _Size>
-inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Tp& get(const array<_Tp, _Size>& __a) _NOEXCEPT {
+[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Tp&
+get(const array<_Tp, _Size>& __a) _NOEXCEPT {
static_assert(_Ip < _Size, "Index out of bounds in std::get<> (const std::array)");
return __a.__elems_[_Ip];
}
template <size_t _Ip, class _Tp, size_t _Size>
-inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp&& get(array<_Tp, _Size>&& __a) _NOEXCEPT {
+[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp&& get(array<_Tp, _Size>&& __a) _NOEXCEPT {
static_assert(_Ip < _Size, "Index out of bounds in std::get<> (std::array &&)");
return std::move(__a.__elems_[_Ip]);
}
template <size_t _Ip, class _Tp, size_t _Size>
-inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Tp&& get(const array<_Tp, _Size>&& __a) _NOEXCEPT {
+[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Tp&&
+get(const array<_Tp, _Size>&& __a) _NOEXCEPT {
static_assert(_Ip < _Size, "Index out of bounds in std::get<> (const std::array &&)");
return std::move(__a.__elems_[_Ip]);
}
@@ -539,7 +572,7 @@ __to_array_rvalue_impl(_Tp (&&__arr)[_Size], index_sequence<_Index...>) {
}
template <typename _Tp, size_t _Size>
-_LIBCPP_HIDE_FROM_ABI constexpr array<remove_cv_t<_Tp>, _Size>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr array<remove_cv_t<_Tp>, _Size>
to_array(_Tp (&__arr)[_Size]) noexcept(is_nothrow_constructible_v<_Tp, _Tp&>) {
static_assert(!is_array_v<_Tp>, "[array.creation]/1: to_array does not accept multidimensional arrays.");
static_assert(is_constructible_v<_Tp, _Tp&>, "[array.creation]/1: to_array requires copy constructible elements.");
@@ -547,7 +580,7 @@ to_array(_Tp (&__arr)[_Size]) noexcept(is_nothrow_constructible_v<_Tp, _Tp&>) {
}
template <typename _Tp, size_t _Size>
-_LIBCPP_HIDE_FROM_ABI constexpr array<remove_cv_t<_Tp>, _Size>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr array<remove_cv_t<_Tp>, _Size>
to_array(_Tp (&&__arr)[_Size]) noexcept(is_nothrow_move_constructible_v<_Tp>) {
static_assert(!is_array_v<_Tp>, "[array.creation]/4: to_array does not accept multidimensional arrays.");
static_assert(is_move_constructible_v<_Tp>, "[array.creation]/4: to_array requires move constructible elements.");
diff --git a/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp b/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
index 25a2f80b48f02..15bfdcc4f9e8c 100644
--- a/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
@@ -11,13 +11,96 @@
// check that <array> functions are marked [[nodiscard]]
#include <array>
+#include <utility>
+
+#include <test_macros.h>
void array_test() {
- std::array<int, 1> array;
- array.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::array<int, 1> a;
+ const std::array<int, 1> ca{9482};
+
+ a.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.cbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.cbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.cend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.cend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.crend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.crend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ a.size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.max_size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ a[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.at(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.at(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ a.front(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.front(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.back(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.back(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ a.data(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.data(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ std::get<0>(a); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::get<0>(ca); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::get<0>(std::move(a));
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::get<0>(std::move(ca));
+
+#if TEST_STD_VER >= 20
+ std::to_array("zmt"); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::to_array({94, 82}); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+#endif
}
void empty_array_test() {
- std::array<int, 0> array;
- array.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::array<int, 0> a;
+ const std::array<int, 0> ca;
+
+ a.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.cbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.cbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.cend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.cend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.crend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.crend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ a.size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.max_size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ a[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.at(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.at(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ a.front(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.front(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.back(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.back(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ a.data(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.data(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}
diff --git a/libcxx/test/std/containers/sequences/array/array.creation/to_array.verify.cpp b/libcxx/test/std/containers/sequences/array/array.creation/to_array.verify.cpp
index e3efef988f0f4..b0e4b63d9a857 100644
--- a/libcxx/test/std/containers/sequences/array/array.creation/to_array.verify.cpp
+++ b/libcxx/test/std/containers/sequences/array/array.creation/to_array.verify.cpp
@@ -6,38 +6,42 @@
//
//===----------------------------------------------------------------------===//
-// <array>
// UNSUPPORTED: c++03, c++11, c++14, c++17
+// <array>
+
+// template <class T, size_t N>
+// constexpr array<remove_cv_t<T>, N> to_array(T (&a)[N]);
+// template <class T, size_t N>
+// constexpr array<remove_cv_t<T>, N> to_array(T (&&a)[N]);
+
#include <array>
-#include "test_macros.h"
#include "MoveOnly.h"
+#include "test_macros.h"
// expected-warning at array:* 0-1 {{suggest braces around initialization of subobject}}
-int main(int, char**) {
+void test() {
{
char source[3][6] = {"hi", "world"};
// expected-error at array:* {{to_array does not accept multidimensional arrays}}
// expected-error at array:* {{to_array requires copy constructible elements}}
// expected-error at array:* 3 {{cannot initialize}}
- std::to_array(source); // expected-note {{requested here}}
+ (void)std::to_array(source); // expected-note {{requested here}}
}
{
MoveOnly mo[] = {MoveOnly{3}};
// expected-error at array:* {{to_array requires copy constructible elements}}
// expected-error-re at array:* 1-2{{{{(call to implicitly-deleted copy constructor of 'MoveOnly')|(call to deleted constructor of 'MoveOnly')}}}}
- std::to_array(mo); // expected-note {{requested here}}
+ (void)std::to_array(mo); // expected-note {{requested here}}
}
{
const MoveOnly cmo[] = {MoveOnly{3}};
// expected-error at array:* {{to_array requires move constructible elements}}
// expected-error-re at array:* 0-1{{{{(call to implicitly-deleted copy constructor of 'MoveOnly')|(call to deleted constructor of 'MoveOnly')}}}}
- std::to_array(std::move(cmo)); // expected-note {{requested here}}
+ (void)std::to_array(std::move(cmo)); // expected-note {{requested here}}
}
-
- return 0;
}
>From d47bfcd50a1958f20ba9556347726a7db3cf53e4 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Thu, 20 Nov 2025 18:57:24 +0200
Subject: [PATCH 2/7] Review comments
---
libcxx/include/array | 7 ++++---
.../array/array.creation/to_array.verify.cpp | 14 +++++---------
2 files changed, 9 insertions(+), 12 deletions(-)
diff --git a/libcxx/include/array b/libcxx/include/array
index d346b50cfcd7a..0b0c85458999c 100644
--- a/libcxx/include/array
+++ b/libcxx/include/array
@@ -473,8 +473,8 @@ array(_Tp, _Args...) -> array<_Tp, 1 + sizeof...(_Args)>;
# endif
template <class _Tp, size_t _Size>
-inline _LIBCPP_HIDE_FROM_ABI
-_LIBCPP_CONSTEXPR_SINCE_CXX20 bool operator==(const array<_Tp, _Size>& __x, const array<_Tp, _Size>& __y) {
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
+operator==(const array<_Tp, _Size>& __x, const array<_Tp, _Size>& __y) {
return std::equal(__x.begin(), __x.end(), __y.begin());
}
@@ -545,7 +545,8 @@ get(const array<_Tp, _Size>& __a) _NOEXCEPT {
}
template <size_t _Ip, class _Tp, size_t _Size>
-[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp&& get(array<_Tp, _Size>&& __a) _NOEXCEPT {
+[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp&&
+get(array<_Tp, _Size>&& __a) _NOEXCEPT {
static_assert(_Ip < _Size, "Index out of bounds in std::get<> (std::array &&)");
return std::move(__a.__elems_[_Ip]);
}
diff --git a/libcxx/test/std/containers/sequences/array/array.creation/to_array.verify.cpp b/libcxx/test/std/containers/sequences/array/array.creation/to_array.verify.cpp
index b0e4b63d9a857..ee8d8e6cfb2e5 100644
--- a/libcxx/test/std/containers/sequences/array/array.creation/to_array.verify.cpp
+++ b/libcxx/test/std/containers/sequences/array/array.creation/to_array.verify.cpp
@@ -6,23 +6,17 @@
//
//===----------------------------------------------------------------------===//
-// UNSUPPORTED: c++03, c++11, c++14, c++17
-
// <array>
-
-// template <class T, size_t N>
-// constexpr array<remove_cv_t<T>, N> to_array(T (&a)[N]);
-// template <class T, size_t N>
-// constexpr array<remove_cv_t<T>, N> to_array(T (&&a)[N]);
+// UNSUPPORTED: c++03, c++11, c++14, c++17
#include <array>
-#include "MoveOnly.h"
#include "test_macros.h"
+#include "MoveOnly.h"
// expected-warning at array:* 0-1 {{suggest braces around initialization of subobject}}
-void test() {
+int main(int, char**) {
{
char source[3][6] = {"hi", "world"};
// expected-error at array:* {{to_array does not accept multidimensional arrays}}
@@ -44,4 +38,6 @@ void test() {
// expected-error-re at array:* 0-1{{{{(call to implicitly-deleted copy constructor of 'MoveOnly')|(call to deleted constructor of 'MoveOnly')}}}}
(void)std::to_array(std::move(cmo)); // expected-note {{requested here}}
}
+
+ return 0;
}
>From e4ec4d1a11d9fa80258314de14e80831bf6ee74a Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Fri, 21 Nov 2025 06:59:51 +0200
Subject: [PATCH 3/7] Addressed review comments
---
.../diagnostics/array.nodiscard.verify.cpp | 148 ++++++++----------
1 file changed, 64 insertions(+), 84 deletions(-)
diff --git a/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp b/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
index 15bfdcc4f9e8c..dff0cd1c26336 100644
--- a/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
@@ -15,92 +15,72 @@
#include <test_macros.h>
-void array_test() {
- std::array<int, 1> a;
- const std::array<int, 1> ca{9482};
-
- a.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.cbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.cbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.cend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.cend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.crend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.crend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-
- a.size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.max_size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-
- a[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.at(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.at(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-
- a.front(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.front(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.back(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.back(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-
- a.data(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.data(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-
- std::get<0>(a); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- std::get<0>(ca); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
- std::get<0>(std::move(a));
- // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
- std::get<0>(std::move(ca));
+template <std::size_t N>
+void test_members() {
+ std::array<int, N> a;
+ const std::array<int, N> ca{};
+
+ a.begin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.begin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.end(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.end(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.rbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.rbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.rend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.rend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.cbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.cbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.cend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.cend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.crbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.crbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.crend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.crend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ a.size(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.max_size(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.empty(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ a[0]; // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca[0]; // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.at(0); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.at(0); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ a.front(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.front(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.back(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.back(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ a.data(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.data(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+}
+void test_nonmembers() {
+ {
+ std::array<int, 1> a;
+ const std::array<int, 1> ca{};
+
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::get<0>(a);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::get<0>(ca);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::get<0>(std::move(a));
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::get<0>(std::move(ca));
+ }
+
+ {
#if TEST_STD_VER >= 20
- std::to_array("zmt"); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- std::to_array({94, 82}); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::to_array("zmt");
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::to_array({94, 82, 49});
#endif
+ }
}
-void empty_array_test() {
- std::array<int, 0> a;
- const std::array<int, 0> ca;
-
- a.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.cbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.cbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.cend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.cend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.crend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.crend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-
- a.size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.max_size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-
- a[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.at(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.at(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-
- a.front(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.front(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.back(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.back(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-
- a.data(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.data(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-}
+void test() {
+ test_members<0>();
+ test_members<82>();
+}
\ No newline at end of file
>From 5c44d0835558b6867dde9237b06bbe647fb7e7d5 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Fri, 21 Nov 2025 07:07:23 +0200
Subject: [PATCH 4/7] Formatting
---
libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp b/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
index dff0cd1c26336..1ee5fe5f77884 100644
--- a/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
@@ -83,4 +83,4 @@ void test_nonmembers() {
void test() {
test_members<0>();
test_members<82>();
-}
\ No newline at end of file
+}
>From 21b948f21f2d96b99c1bf6a766e64daf2389bf06 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Fri, 21 Nov 2025 09:34:06 +0200
Subject: [PATCH 5/7] Shorten test
---
.../diagnostics/array.nodiscard.verify.cpp | 93 ++++++++-----------
1 file changed, 39 insertions(+), 54 deletions(-)
diff --git a/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp b/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
index 1ee5fe5f77884..4c99c3cc0f6b3 100644
--- a/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
@@ -15,72 +15,57 @@
#include <test_macros.h>
-template <std::size_t N>
+template <typename ArrT>
void test_members() {
- std::array<int, N> a;
- const std::array<int, N> ca{};
+ ArrT a{};
- a.begin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.begin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.end(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.end(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.rbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.rbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.rend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.rend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.cbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.cbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.cend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.cend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.crbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.crbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.crend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.crend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.begin(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.end(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.rbegin(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.rend(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.cbegin(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.cend(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.crbegin(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.crend(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.size(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.max_size(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.empty(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.size(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.max_size(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.empty(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a[0]; // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca[0]; // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.at(0); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.at(0); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a[0]; // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.at(0); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.front(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.front(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.back(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.back(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.front(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.back(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.data(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- ca.data(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.data(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
}
-void test_nonmembers() {
- {
- std::array<int, 1> a;
- const std::array<int, 1> ca{};
+template <typename ArrT>
+void test_get() {
+ ArrT a{};
- // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
- std::get<0>(a);
- // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
- std::get<0>(ca);
- // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
- std::get<0>(std::move(a));
- // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
- std::get<0>(std::move(ca));
- }
+ // expected-warning at +1 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::get<0>(a);
+ // expected-warning at +1 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::get<0>(std::move(a));
+}
- {
#if TEST_STD_VER >= 20
- // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
- std::to_array("zmt");
- // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
- std::to_array({94, 82, 49});
-#endif
- }
+void test_to_array() {
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::to_array("zmt");
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::to_array({94, 82, 49});
}
+#endif
void test() {
- test_members<0>();
- test_members<82>();
+ test_members<std::array<int, 82>>();
+ test_members<const std::array<int, 82>>();
+ test_members<std::array<int, 0>>();
+ test_members<const std::array<int, 0>>();
+
+ test_get<std::array<int, 82>>();
+ test_get<const std::array<int, 82>>();
}
>From 679fbf0b4fdaf9c8fe335e0950afd9cf18340b98 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Fri, 21 Nov 2025 18:18:03 +0200
Subject: [PATCH 6/7] Lengthen test
---
.../diagnostics/array.nodiscard.verify.cpp | 65 +++++++++++--------
1 file changed, 37 insertions(+), 28 deletions(-)
diff --git a/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp b/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
index 4c99c3cc0f6b3..a248bf88d8473 100644
--- a/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
@@ -15,39 +15,53 @@
#include <test_macros.h>
-template <typename ArrT>
+template <std::size_t N>
void test_members() {
- ArrT a{};
+ std::array<int, N> a;
+ const std::array<int, N> ca{};
- a.begin(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.end(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.rbegin(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.rend(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.cbegin(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.cend(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.crbegin(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.crend(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.begin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.begin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.end(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.end(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.rbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.rbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.rend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.rend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.cbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.cbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.cend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.cend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.crbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.crbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.crend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.crend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.size(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.max_size(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.empty(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.size(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.max_size(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.empty(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a[0]; // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.at(0); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a[0]; // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca[0]; // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.at(0); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.at(0); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.front(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.back(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.front(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.front(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.back(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.back(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
- a.data(); // expected-warning 4 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ a.data(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ca.data(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
}
template <typename ArrT>
void test_get() {
- ArrT a{};
+ std::array<int> a{};
- // expected-warning at +1 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
std::get<0>(a);
- // expected-warning at +1 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
std::get<0>(std::move(a));
}
@@ -61,11 +75,6 @@ void test_to_array() {
#endif
void test() {
- test_members<std::array<int, 82>>();
- test_members<const std::array<int, 82>>();
- test_members<std::array<int, 0>>();
- test_members<const std::array<int, 0>>();
-
- test_get<std::array<int, 82>>();
- test_get<const std::array<int, 82>>();
+ test_members<0>();
+ test_members<82>();
}
>From d8790a10f6d4606f28a1bfb5f4bcdefaa55b7d4d Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Fri, 21 Nov 2025 18:19:00 +0200
Subject: [PATCH 7/7] Fix
---
libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp b/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
index a248bf88d8473..8e49807732de7 100644
--- a/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/array.nodiscard.verify.cpp
@@ -57,7 +57,7 @@ void test_members() {
template <typename ArrT>
void test_get() {
- std::array<int> a{};
+ std::array<int, 94> a{};
// expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
std::get<0>(a);
More information about the libcxx-commits
mailing list