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[libc++][list] Applied [[nodiscard]] #169015

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Nov 24, 2025
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[libc++][list] Applied [[nodiscard]] #169015

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52 changes: 33 additions & 19 deletions libcxx/include/list
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Original file line number Diff line number Diff line change
Expand Up @@ -774,57 +774,71 @@ public:

_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI void assign(size_type __n, const value_type& __x);

_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT;
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT;

_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return this->__size_; }
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT {
return this->__size_;
}
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT {
return __base::empty();
}
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
return std::min<size_type>(this->__node_alloc_max_size(), numeric_limits<difference_type >::max());
}

_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return __base::begin(); }
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return __base::begin(); }
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return __base::end(); }
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return __base::end(); }
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT {
return __base::begin();
}
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT {
return __base::begin();
}
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT {
return __base::end();
}
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT {
return __base::end();
}
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT {
return __base::begin();
}
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT { return __base::end(); }
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT {
return __base::end();
}

_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI reverse_iterator rbegin() _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI reverse_iterator rbegin() _NOEXCEPT {
return reverse_iterator(end());
}
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator
rbegin() const _NOEXCEPT {
return const_reverse_iterator(end());
}
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI reverse_iterator rend() _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI reverse_iterator rend() _NOEXCEPT {
return reverse_iterator(begin());
}
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT {
return const_reverse_iterator(begin());
}
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator
crbegin() const _NOEXCEPT {
return const_reverse_iterator(end());
}
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT {
return const_reverse_iterator(begin());
}

_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI reference front() {
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI reference front() {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::front called on empty list");
return __base::__end_.__next_->__as_node()->__get_value();
}
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_reference front() const {
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_reference front() const {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::front called on empty list");
return __base::__end_.__next_->__as_node()->__get_value();
}
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI reference back() {
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI reference back() {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::back called on empty list");
return __base::__end_.__prev_->__as_node()->__get_value();
}
_LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_reference back() const {
[[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX26 _LIBCPP_HIDE_FROM_ABI const_reference back() const {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::back called on empty list");
return __base::__end_.__prev_->__as_node()->__get_value();
}
Expand Down
31 changes: 29 additions & 2 deletions libcxx/test/libcxx/diagnostics/list.nodiscard.verify.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,33 @@
#include <list>

void test() {
std::list<int> list;
list.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
std::list<int> l;
const std::list<int> cl;

l.get_allocator(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
l.size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
l.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
l.max_size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}

l.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
cl.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
l.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
cl.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
l.cbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
cl.cbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
l.cend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
cl.cend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
l.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
cl.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
l.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
cl.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
l.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
cl.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
l.crend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
cl.crend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}

l.front(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
cl.front(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
l.back(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
cl.back(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}
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