From b43f134a68420663b25f63e46ffae2850ff25760 Mon Sep 17 00:00:00 2001 From: Hristo Hristov Date: Wed, 10 Dec 2025 19:13:02 +0200 Subject: [PATCH] [libc++][multiset] Applied [[nodiscard]] `[[nodiscard]]` should be applied to functions where discarding the return value is most likely a correctness issue. - https://libcxx.llvm.org/CodingGuidelines.htm - https://wg21.link/multiset --- libcxx/include/set | 88 +++++++------- .../diagnostics/multiset.nodiscard.verify.cpp | 107 ++++++++++++++++++ 2 files changed, 156 insertions(+), 39 deletions(-) create mode 100644 libcxx/test/libcxx/diagnostics/multiset.nodiscard.verify.cpp diff --git a/libcxx/include/set b/libcxx/include/set index 3d6f571a42a1a..1dedae29da6b1 100644 --- a/libcxx/include/set +++ b/libcxx/include/set @@ -1147,24 +1147,28 @@ public: static_assert(sizeof(std::__diagnose_non_const_comparator<_Key, _Compare>()), ""); } - _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return __tree_.begin(); } - _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return __tree_.begin(); } - _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return __tree_.end(); } - _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return __tree_.end(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return __tree_.begin(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return __tree_.begin(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return __tree_.end(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return __tree_.end(); } - _LIBCPP_HIDE_FROM_ABI reverse_iterator rbegin() _NOEXCEPT { return reverse_iterator(end()); } - _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT { return const_reverse_iterator(end()); } - _LIBCPP_HIDE_FROM_ABI reverse_iterator rend() _NOEXCEPT { return reverse_iterator(begin()); } - _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT { return const_reverse_iterator(begin()); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI reverse_iterator rbegin() _NOEXCEPT { return reverse_iterator(end()); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT { + return const_reverse_iterator(end()); + } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI reverse_iterator rend() _NOEXCEPT { return reverse_iterator(begin()); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT { + return const_reverse_iterator(begin()); + } - _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT { return begin(); } - _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT { return end(); } - _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT { return rbegin(); } - _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT { return rend(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT { return begin(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT { return end(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT { return rbegin(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT { return rend(); } [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT { return __tree_.size() == 0; } - _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __tree_.size(); } - _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT { return __tree_.max_size(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __tree_.size(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT { return __tree_.max_size(); } // modifiers: # ifndef _LIBCPP_CXX03_LANG @@ -1221,10 +1225,10 @@ public: "node_type with incompatible allocator passed to multiset::insert()"); return __tree_.template __node_handle_insert_multi(__hint, std::move(__nh)); } - _LIBCPP_HIDE_FROM_ABI node_type extract(key_type const& __key) { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI node_type extract(key_type const& __key) { return __tree_.template __node_handle_extract(__key); } - _LIBCPP_HIDE_FROM_ABI node_type extract(const_iterator __it) { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI node_type extract(const_iterator __it) { return __tree_.template __node_handle_extract(__it); } template @@ -1257,88 +1261,94 @@ public: __tree_.swap(__s.__tree_); } - _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT { return __tree_.__alloc(); } - _LIBCPP_HIDE_FROM_ABI key_compare key_comp() const { return __tree_.value_comp(); } - _LIBCPP_HIDE_FROM_ABI value_compare value_comp() const { return __tree_.value_comp(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT { return __tree_.__alloc(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI key_compare key_comp() const { return __tree_.value_comp(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI value_compare value_comp() const { return __tree_.value_comp(); } // set operations: - _LIBCPP_HIDE_FROM_ABI iterator find(const key_type& __k) { return __tree_.find(__k); } - _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const { return __tree_.find(__k); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI iterator find(const key_type& __k) { return __tree_.find(__k); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const { return __tree_.find(__k); } # if _LIBCPP_STD_VER >= 14 template , int> = 0> - _LIBCPP_HIDE_FROM_ABI iterator find(const _K2& __k) { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI iterator find(const _K2& __k) { return __tree_.find(__k); } template , int> = 0> - _LIBCPP_HIDE_FROM_ABI const_iterator find(const _K2& __k) const { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_iterator find(const _K2& __k) const { return __tree_.find(__k); } # endif - _LIBCPP_HIDE_FROM_ABI size_type count(const key_type& __k) const { return __tree_.__count_multi(__k); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_type count(const key_type& __k) const { + return __tree_.__count_multi(__k); + } # if _LIBCPP_STD_VER >= 14 template , int> = 0> - _LIBCPP_HIDE_FROM_ABI size_type count(const _K2& __k) const { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_type count(const _K2& __k) const { return __tree_.__count_multi(__k); } # endif # if _LIBCPP_STD_VER >= 20 - _LIBCPP_HIDE_FROM_ABI bool contains(const key_type& __k) const { return find(__k) != end(); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool contains(const key_type& __k) const { return find(__k) != end(); } template , int> = 0> - _LIBCPP_HIDE_FROM_ABI bool contains(const _K2& __k) const { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool contains(const _K2& __k) const { return find(__k) != end(); } # endif // _LIBCPP_STD_VER >= 20 - _LIBCPP_HIDE_FROM_ABI iterator lower_bound(const key_type& __k) { return __tree_.__lower_bound_multi(__k); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI iterator lower_bound(const key_type& __k) { + return __tree_.__lower_bound_multi(__k); + } - _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const key_type& __k) const { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const key_type& __k) const { return __tree_.__lower_bound_multi(__k); } # if _LIBCPP_STD_VER >= 14 template , int> = 0> - _LIBCPP_HIDE_FROM_ABI iterator lower_bound(const _K2& __k) { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI iterator lower_bound(const _K2& __k) { return __tree_.__lower_bound_multi(__k); } template , int> = 0> - _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const _K2& __k) const { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const _K2& __k) const { return __tree_.__lower_bound_multi(__k); } # endif - _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const key_type& __k) { return __tree_.__upper_bound_multi(__k); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const key_type& __k) { + return __tree_.__upper_bound_multi(__k); + } - _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const key_type& __k) const { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const key_type& __k) const { return __tree_.__upper_bound_multi(__k); } # if _LIBCPP_STD_VER >= 14 template , int> = 0> - _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const _K2& __k) { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const _K2& __k) { return __tree_.__upper_bound_multi(__k); } template , int> = 0> - _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const _K2& __k) const { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const _K2& __k) const { return __tree_.__upper_bound_multi(__k); } # endif - _LIBCPP_HIDE_FROM_ABI pair equal_range(const key_type& __k) { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI pair equal_range(const key_type& __k) { return __tree_.__equal_range_multi(__k); } - _LIBCPP_HIDE_FROM_ABI pair equal_range(const key_type& __k) const { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI pair equal_range(const key_type& __k) const { return __tree_.__equal_range_multi(__k); } # if _LIBCPP_STD_VER >= 14 template , int> = 0> - _LIBCPP_HIDE_FROM_ABI pair equal_range(const _K2& __k) { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI pair equal_range(const _K2& __k) { return __tree_.__equal_range_multi(__k); } template , int> = 0> - _LIBCPP_HIDE_FROM_ABI pair equal_range(const _K2& __k) const { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI pair equal_range(const _K2& __k) const { return __tree_.__equal_range_multi(__k); } # endif diff --git a/libcxx/test/libcxx/diagnostics/multiset.nodiscard.verify.cpp b/libcxx/test/libcxx/diagnostics/multiset.nodiscard.verify.cpp new file mode 100644 index 0000000000000..889b3cc62d191 --- /dev/null +++ b/libcxx/test/libcxx/diagnostics/multiset.nodiscard.verify.cpp @@ -0,0 +1,107 @@ +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +// Check that functions are marked [[nodiscard]] + +#include + +#include "test_macros.h" + +#if TEST_STD_VER >= 14 +struct TransparentKey { + explicit operator int() const; +}; + +struct TransparentCompare { + using is_transparent = void; // This makes the comparator transparent + + bool operator()(const int&, const TransparentKey&) const; + + bool operator()(const TransparentKey&, const int&) const; + + bool operator()(const int&, const int&) const; +}; +#endif + +void test() { + std::multiset s; + const std::multiset cs; + + s.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + s.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + + s.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + s.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + + cs.cbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.cend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.crend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + + s.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + s.size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + s.max_size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + + int key = 0; + +#if TEST_STD_VER >= 17 + s.extract(key); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + s.extract(s.begin()); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +#endif + + s.get_allocator(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + s.key_comp(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + s.value_comp(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + + s.find(key); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.find(key); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +#if TEST_STD_VER >= 14 + std::multiset ts; + const std::multiset cts{}; + + TransparentKey tkey; + + ts.find(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cts.find(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +#endif + + s.count(key); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +#if TEST_STD_VER >= 14 + ts.count(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +#endif + +#if TEST_STD_VER >= 20 + s.contains(key); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + ts.contains(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +#endif + + s.lower_bound(key); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.lower_bound(key); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +#if TEST_STD_VER >= 14 + ts.lower_bound(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cts.lower_bound(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +#endif + + s.upper_bound(key); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.upper_bound(key); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +#if TEST_STD_VER >= 14 + ts.upper_bound(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cts.upper_bound(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +#endif + + s.equal_range(key); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.equal_range(key); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +#if TEST_STD_VER >= 14 + ts.equal_range(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + cts.equal_range(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} +#endif +}