[libc++][list] Applied [[nodiscard]]
#169015
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@llvm/pr-subscribers-libcxx Author: Hristo Hristov (H-G-Hristov) Changes
Full diff: https://github.com/llvm/llvm-project/pull/169015.diff 2 Files Affected:
diff --git a/libcxx/include/list b/libcxx/include/list
index 2898a45da0029..518d91dbf1e50 100644
--- a/libcxx/include/list
+++ b/libcxx/include/list
@@ -774,57 +774,57 @@ 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();
}
diff --git a/libcxx/test/libcxx/diagnostics/list.nodiscard.verify.cpp b/libcxx/test/libcxx/diagnostics/list.nodiscard.verify.cpp
index f19224a71f5cc..9e7029b5794d4 100644
--- a/libcxx/test/libcxx/diagnostics/list.nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/list.nodiscard.verify.cpp
@@ -12,7 +12,29 @@
#include <list>
+template <typename ListT>
void test() {
- std::list<int> list;
- list.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ListT list{};
+
+ list.get_allocator(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ list.size(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ list.empty(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ list.max_size(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ list.begin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ list.end(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ list.cbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ list.cend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ list.rbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ list.rend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ list.crbegin(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ list.crend(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ list.front(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ list.back(); // expected-warning 2 {{ignoring return value of function declared with 'nodiscard' attribute}}
+}
+
+void test() {
+ test<std::list<int>>();
+ test<const std::list<int>>();
}
|
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✅ With the latest revision this PR passed the C/C++ code formatter. |
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`[[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
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philnik777
approved these changes
Nov 24, 2025
aadeshps-mcw
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`[[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
Priyanshu3820
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`[[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
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[[nodiscard]]should be applied to functions where discarding the return value is most likely a correctness issue.