Addressed comments

Author: H-G-Hristov

libcxx/include/__flat_map/flat_map.h

@@ -600,7 +600,7 @@ class flat_map {
     insert(sorted_unique, __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;

libcxx/test/libcxx/diagnostics/flat_map.nodiscard.verify.cpp

@@ -53,7 +53,7 @@ void test() {
   cfm.rbegin();  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
   fm.rend();     // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
   cfm.rend();    // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-  cfm.begin();   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cfm.cbegin();  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
   cfm.cend();    // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
   cfm.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
   cfm.crend();   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
@@ -62,8 +62,6 @@ void test() {
   fm.size();     // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
   fm.max_size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
 
-  fm.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-
   int key = 0;
   TransparentKey<int> tkey;
 
@@ -77,6 +75,8 @@ void test() {
   fm.at(tkey);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
   cfm.at(tkey); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
 
+  std::move(fm).extract(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
   fm.key_comp();   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
   fm.value_comp(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
   fm.keys();       // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}