[libc++][flat_multimap] Applied `[[nodiscard]]` #169986

H-G-Hristov · 2025-11-29T10:45:59Z

[[nodiscard]] should be applied to functions where discarding the return value is most likely a correctness issue.

`[[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/map

llvmbot · 2025-11-29T10:46:30Z

@llvm/pr-subscribers-libcxx

Author: Hristo Hristov (H-G-Hristov)

Changes

[[nodiscard]] should be applied to functions where discarding the return value is most likely a correctness issue.

Full diff: https://github.com/llvm/llvm-project/pull/169986.diff

2 Files Affected:

(modified) libcxx/include/__flat_map/flat_multimap.h (+48-39)
(modified) libcxx/test/libcxx/diagnostics/flat_multimap.nodiscard.verify.cpp (+87-7)

diff --git a/libcxx/include/__flat_map/flat_multimap.h b/libcxx/include/__flat_map/flat_multimap.h
index 6a608723da1ba..3db669066ba97 100644
--- a/libcxx/include/__flat_map/flat_multimap.h
+++ b/libcxx/include/__flat_map/flat_multimap.h
@@ -408,41 +408,45 @@ class flat_multimap {
   }
 
   // iterators
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator begin() noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator begin() noexcept {
     return iterator(__containers_.keys.begin(), __containers_.values.begin());
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator begin() const noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator begin() const noexcept {
     return const_iterator(__containers_.keys.begin(), __containers_.values.begin());
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator end() noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator end() noexcept {
     return iterator(__containers_.keys.end(), __containers_.values.end());
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator end() const noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator end() const noexcept {
     return const_iterator(__containers_.keys.end(), __containers_.values.end());
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 reverse_iterator rbegin() noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 reverse_iterator rbegin() noexcept {
     return reverse_iterator(end());
   }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_reverse_iterator rbegin() const noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_reverse_iterator rbegin() const noexcept {
     return const_reverse_iterator(end());
   }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 reverse_iterator rend() noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 reverse_iterator rend() noexcept {
     return reverse_iterator(begin());
   }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_reverse_iterator rend() const noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_reverse_iterator rend() const noexcept {
     return const_reverse_iterator(begin());
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator cbegin() const noexcept { return begin(); }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator cend() const noexcept { return end(); }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_reverse_iterator crbegin() const noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator cbegin() const noexcept {
+    return begin();
+  }
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator cend() const noexcept {
+    return end();
+  }
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_reverse_iterator crbegin() const noexcept {
     return const_reverse_iterator(end());
   }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_reverse_iterator crend() const noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_reverse_iterator crend() const noexcept {
     return const_reverse_iterator(begin());
   }
 
@@ -451,11 +455,11 @@ class flat_multimap {
     return __containers_.keys.empty();
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 size_type size() const noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 size_type size() const noexcept {
     return __containers_.keys.size();
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 size_type max_size() const noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 size_type max_size() const noexcept {
     return std::min<size_type>(__containers_.keys.max_size(), __containers_.values.max_size());
   }
 
@@ -578,7 +582,7 @@ class flat_multimap {
     insert(sorted_equivalent, __il.begin(), __il.end());
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 containers extract() && {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 containers extract() && {
     auto __guard = std::__make_scope_guard([&]() noexcept { clear() /* noexcept */; });
     auto __ret   = std::move(__containers_);
     return __ret;
@@ -644,118 +648,123 @@ class flat_multimap {
   }
 
   // observers
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 key_compare key_comp() const { return __compare_; }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 value_compare value_comp() const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 key_compare key_comp() const { return __compare_; }
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 value_compare value_comp() const {
     return value_compare(__compare_);
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const key_container_type& keys() const noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const key_container_type& keys() const noexcept {
     return __containers_.keys;
   }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const mapped_container_type& values() const noexcept {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const mapped_container_type&
+  values() const noexcept {
     return __containers_.values;
   }
 
   // map operations
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator find(const key_type& __x) {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator find(const key_type& __x) {
     return __find_impl(*this, __x);
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator find(const key_type& __x) const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator find(const key_type& __x) const {
     return __find_impl(*this, __x);
   }
 
   template <class _Kp>
     requires __is_compare_transparent
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator find(const _Kp& __x) {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator find(const _Kp& __x) {
     return __find_impl(*this, __x);
   }
 
   template <class _Kp>
     requires __is_compare_transparent
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator find(const _Kp& __x) const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator find(const _Kp& __x) const {
     return __find_impl(*this, __x);
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 size_type count(const key_type& __x) const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 size_type count(const key_type& __x) const {
     auto [__first, __last] = equal_range(__x);
     return __last - __first;
   }
 
   template <class _Kp>
     requires __is_compare_transparent
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 size_type count(const _Kp& __x) const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 size_type count(const _Kp& __x) const {
     auto [__first, __last] = equal_range(__x);
     return __last - __first;
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool contains(const key_type& __x) const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool contains(const key_type& __x) const {
     return find(__x) != end();
   }
 
   template <class _Kp>
     requires __is_compare_transparent
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool contains(const _Kp& __x) const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool contains(const _Kp& __x) const {
     return find(__x) != end();
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator lower_bound(const key_type& __x) {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator lower_bound(const key_type& __x) {
     return __lower_bound<iterator>(*this, __x);
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator lower_bound(const key_type& __x) const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator
+  lower_bound(const key_type& __x) const {
     return __lower_bound<const_iterator>(*this, __x);
   }
 
   template <class _Kp>
     requires __is_compare_transparent
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator lower_bound(const _Kp& __x) {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator lower_bound(const _Kp& __x) {
     return __lower_bound<iterator>(*this, __x);
   }
 
   template <class _Kp>
     requires __is_compare_transparent
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator lower_bound(const _Kp& __x) const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator lower_bound(const _Kp& __x) const {
     return __lower_bound<const_iterator>(*this, __x);
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator upper_bound(const key_type& __x) {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator upper_bound(const key_type& __x) {
     return __upper_bound<iterator>(*this, __x);
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator upper_bound(const key_type& __x) const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator
+  upper_bound(const key_type& __x) const {
     return __upper_bound<const_iterator>(*this, __x);
   }
 
   template <class _Kp>
     requires __is_compare_transparent
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator upper_bound(const _Kp& __x) {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 iterator upper_bound(const _Kp& __x) {
     return __upper_bound<iterator>(*this, __x);
   }
 
   template <class _Kp>
     requires __is_compare_transparent
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator upper_bound(const _Kp& __x) const {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const_iterator upper_bound(const _Kp& __x) const {
     return __upper_bound<const_iterator>(*this, __x);
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 pair<iterator, iterator> equal_range(const key_type& __x) {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 pair<iterator, iterator>
+  equal_range(const key_type& __x) {
     return __equal_range_impl(*this, __x);
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 pair<const_iterator, const_iterator>
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 pair<const_iterator, const_iterator>
   equal_range(const key_type& __x) const {
     return __equal_range_impl(*this, __x);
   }
 
   template <class _Kp>
     requires __is_compare_transparent
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 pair<iterator, iterator> equal_range(const _Kp& __x) {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 pair<iterator, iterator>
+  equal_range(const _Kp& __x) {
     return __equal_range_impl(*this, __x);
   }
   template <class _Kp>
     requires __is_compare_transparent
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 pair<const_iterator, const_iterator>
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 pair<const_iterator, const_iterator>
   equal_range(const _Kp& __x) const {
     return __equal_range_impl(*this, __x);
   }
diff --git a/libcxx/test/libcxx/diagnostics/flat_multimap.nodiscard.verify.cpp b/libcxx/test/libcxx/diagnostics/flat_multimap.nodiscard.verify.cpp
index 9b7b827c9bec8..66d6c99aed70c 100644
--- a/libcxx/test/libcxx/diagnostics/flat_multimap.nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/flat_multimap.nodiscard.verify.cpp
@@ -6,17 +6,97 @@
 //
 //===----------------------------------------------------------------------===//
 
-// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// REQUIRES: std-at-least-c++23
 
 // <flat_map>
 
-// class flat_multimap
-
-// [[nodiscard]] bool empty() const noexcept;
+// Check that functions are marked [[nodiscard]]
 
 #include <flat_map>
+#include <utility>
+
+template <typename T>
+struct TransparentKey {
+  T t;
+
+  constexpr explicit operator T() const { return t; }
+};
+
+struct TransparentCompare {
+  using is_transparent = void; // This makes the comparator transparent
+
+  template <typename T>
+  constexpr bool operator()(const T& t, const TransparentKey<T>& transparent) const {
+    return t < transparent.t;
+  }
+
+  template <typename T>
+  constexpr bool operator()(const TransparentKey<T>& transparent, const T& t) const {
+    return transparent.t < t;
+  }
+
+  template <typename T>
+  constexpr bool operator()(const T& t1, const T& t2) const {
+    return t1 < t2;
+  }
+};
+
+void test() {
+  std::flat_multimap<int, int, TransparentCompare> mm;
+  const std::flat_multimap<int, int, TransparentCompare> cmm;
+
+  mm.begin();  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.end();    // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.end();   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  mm.rbegin();  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.rend();    // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.rend();   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  cmm.cbegin();  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.cend();    // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.crend();   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  mm.empty();    // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.size();     // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.max_size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  mm.key_comp();   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.value_comp(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.keys();       // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.values();     // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  int key = 0;
+  TransparentKey<int> tkey;
+
+  mm.find(key);   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.find(key);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.find(tkey);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.find(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  mm.count(key);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.count(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  mm.contains(key);   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.contains(key);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.contains(tkey);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.contains(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  mm.lower_bound(key);   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.lower_bound(key);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.lower_bound(tkey);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.lower_bound(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  mm.upper_bound(key);   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.upper_bound(key);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.upper_bound(tkey);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.upper_bound(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
 
-void f() {
-  std::flat_multimap<int, int> c;
-  c.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.equal_range(key);   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.equal_range(key);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  mm.equal_range(tkey);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cmm.equal_range(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
 }

libcxx/include/__flat_map/flat_multimap.h

frederick-vs-ja · 2025-12-14T08:46:52Z

Merging with obvious fix for the PR description/squashed commit message.

`[[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/flat.multimap

[libc++][flat_multimap] Applied [[nodiscard]]

6804808

`[[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/map

H-G-Hristov requested a review from a team as a code owner November 29, 2025 10:46

llvmbot added the libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. label Nov 29, 2025

huixie90 reviewed Nov 30, 2025

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libcxx/include/__flat_map/flat_multimap.h Show resolved Hide resolved

H-G-Hristov mentioned this pull request Dec 13, 2025

[libc++] Apply [[nodiscard]] to the Standard Library #172124

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frederick-vs-ja approved these changes Dec 14, 2025

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frederick-vs-ja merged commit 61f4cc7 into llvm:main Dec 14, 2025
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[libc++][flat_multimap] Applied `[[nodiscard]]` #169986

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[libc++][flat_multimap] Applied `[[nodiscard]]` #169986

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