libstdc++: Fix availability of std::erase_if(std::flat_foo) [PR119427]

These std::erase_if overloads were wrongly implemented as hidden
friends, visible only via ADL, so erase_if(x) would work but not
std::erase_if(x).

	PR libstdc++/119427

libstdc++-v3/ChangeLog:

	* include/std/flat_map (_Flat_map_impl::erase_if): Replace
	this hidden friend with ...
	(_Flat_map_impl::_M_erase_if): ... this member function.
	(flat_map): Export _Flat_map_impl::_M_erase_if.
	(erase_if(flat_map)): Define.
	(flat_multimap): Export _Flat_map_impl::_M_erase_if.
	(erase_if(flat_multimap)): Define.
	* include/std/flat_set (_Flat_set_impl::erase_if): Replace
	with ...
	(_Flat_set_impl::_M_erase_if): ... this member function.
	(flat_set): Export _Flat_set_impl::_M_erase_if.
	(erase_if(flat_set)): Define.
	(flat_multiset): Export _Flat_set_impl::_M_erase_if.
	(erase_if(flat_multiset)): Define.
	* testsuite/23_containers/flat_map/1.cc (test07): New test.
	* testsuite/23_containers/flat_multimap/1.cc (test07): New test.
	* testsuite/23_containers/flat_multiset/1.cc (test09): New test.
	* testsuite/23_containers/flat_set/1.cc (test09): New test.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
(cherry picked from commit aa93272cfd2233858da0792761387cc27f4d5ff3)

6 files changed, 89 insertions, 11 deletions

diff --git a/libstdc++-v3/include/std/flat_map b/libstdc++-v3/include/std/flat_map
index 405caa8..6593988 100644
--- a/libstdc++-v3/include/std/flat_map
+++ b/libstdc++-v3/include/std/flat_map
@@ -890,14 +890,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { return __x.swap(__y); }
 
       template<typename _Predicate>
-	friend size_type
-	erase_if(_Derived& __c, _Predicate __pred)
+	size_type
+	_M_erase_if(_Predicate __pred)
 	{
-	  auto __guard = __c._M_make_clear_guard();
-	  auto __zv = views::zip(__c._M_cont.keys, __c._M_cont.values);
+	  auto __guard = _M_make_clear_guard();
+	  auto __zv = views::zip(_M_cont.keys, _M_cont.values);
 	  auto __sr = ranges::remove_if(__zv, __pred);
 	  auto __erased = __sr.size();
-	  __c.erase(__c.end() - __erased, __c.end());
+	  erase(end() - __erased, end());
 	  __guard._M_disable();
 	  return __erased;
 	}
@@ -1329,6 +1329,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       using _Impl::lower_bound;
       using _Impl::upper_bound;
       using _Impl::equal_range;
+
+      using _Impl::_M_erase_if;
     };
 
   template<typename _KeyContainer, typename _MappedContainer,
@@ -1412,6 +1414,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		    && uses_allocator_v<_MappedContainer, _Alloc>>
     { };
 
+  template<typename _Key, typename _Tp, typename _Compare,
+	   typename _KeyContainer, typename _MappedContainer, typename _Predicate>
+    typename flat_map<_Key, _Tp, _Compare, _KeyContainer, _MappedContainer>::size_type
+    erase_if(flat_map<_Key, _Tp, _Compare, _KeyContainer, _MappedContainer>& __c,
+	     _Predicate __pred)
+    { return __c._M_erase_if(std::move(__pred)); }
+
   /* Class template flat_multimap - container adaptor
    *
    * @ingroup
@@ -1487,6 +1496,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       using _Impl::lower_bound;
       using _Impl::upper_bound;
       using _Impl::equal_range;
+
+      using _Impl::_M_erase_if;
     };
 
   template<typename _KeyContainer, typename _MappedContainer,
@@ -1571,6 +1582,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		    && uses_allocator_v<_MappedContainer, _Alloc>>
     { };
 
+  template<typename _Key, typename _Tp, typename _Compare,
+	   typename _KeyContainer, typename _MappedContainer, typename _Predicate>
+    typename flat_multimap<_Key, _Tp, _Compare, _KeyContainer, _MappedContainer>::size_type
+    erase_if(flat_multimap<_Key, _Tp, _Compare, _KeyContainer, _MappedContainer>& __c,
+	     _Predicate __pred)
+    { return __c._M_erase_if(std::move(__pred)); }
+
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std
 #endif // __cpp_lib_flat_map
diff --git a/libstdc++-v3/include/std/flat_set b/libstdc++-v3/include/std/flat_set
index 3e15d1a..c48340d 100644
--- a/libstdc++-v3/include/std/flat_set
+++ b/libstdc++-v3/include/std/flat_set
@@ -745,15 +745,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { return __x.swap(__y); }
 
       template<typename _Predicate>
-	friend size_type
-	erase_if(_Derived& __c, _Predicate __pred)
+	size_type
+	_M_erase_if(_Predicate __pred)
 	{
-	  auto __guard = __c._M_make_clear_guard();
-	  auto __first = __c._M_cont.begin();
-	  auto __last = __c._M_cont.end();
+	  auto __guard = _M_make_clear_guard();
+	  auto __first = _M_cont.begin();
+	  auto __last = _M_cont.end();
 	  __first = std::remove_if(__first, __last, __pred);
 	  auto __n = __last - __first;
-	  __c.erase(__first, __last);
+	  erase(__first, __last);
 	  __guard._M_disable();
 	  return __n;
 	}
@@ -860,6 +860,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       using _Impl::lower_bound;
       using _Impl::upper_bound;
       using _Impl::equal_range;
+
+      using _Impl::_M_erase_if;
     };
 
   template<typename _KeyContainer,
@@ -930,6 +932,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     : bool_constant<uses_allocator_v<_KeyContainer, _Alloc>>
     { };
 
+  template<typename _Key, typename _Compare, typename _KeyContainer,
+	   typename _Predicate>
+    typename flat_set<_Key, _Compare, _KeyContainer>::size_type
+    erase_if(flat_set<_Key, _Compare, _KeyContainer>& __c, _Predicate __pred)
+    { return __c._M_erase_if(std::move(__pred)); }
+
   /* Class template flat_multiset - container adaptor
    *
    * @ingroup
@@ -999,6 +1007,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       using _Impl::lower_bound;
       using _Impl::upper_bound;
       using _Impl::equal_range;
+
+      using _Impl::_M_erase_if;
     };
 
   template<typename _KeyContainer,
@@ -1069,6 +1079,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     : bool_constant<uses_allocator_v<_KeyContainer, _Alloc>>
     { };
 
+  template<typename _Key, typename _Compare, typename _KeyContainer,
+	   typename _Predicate>
+    typename flat_multiset<_Key, _Compare, _KeyContainer>::size_type
+    erase_if(flat_multiset<_Key, _Compare, _KeyContainer>& __c, _Predicate __pred)
+    { return __c._M_erase_if(std::move(__pred)); }
+
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std
 #endif // __cpp_lib_flat_set
diff --git a/libstdc++-v3/testsuite/23_containers/flat_map/1.cc b/libstdc++-v3/testsuite/23_containers/flat_map/1.cc
index d9d88c4..38fd449 100644
--- a/libstdc++-v3/testsuite/23_containers/flat_map/1.cc
+++ b/libstdc++-v3/testsuite/23_containers/flat_map/1.cc
@@ -241,6 +241,16 @@ test06()
   VERIFY( std::ranges::equal(m | std::views::values, (int[]){2, 3, 4, 5, 6}) );
 }
 
+void
+test07()
+{
+  // PR libstdc++/119427 - std::erase_if(std::flat_foo) does not work
+  std::flat_map<int, int> m = {std::pair{1, 2}, {3, 4}, {5, 6}};
+  auto n = std::erase_if(m, [](auto x) { auto [k,v] = x; return k == 1 || v == 6; });
+  VERIFY( n == 2 );
+  VERIFY( std::ranges::equal(m, (std::pair<int,int>[]){{3,4}}) );
+}
+
 int
 main()
 {
@@ -253,4 +263,5 @@ main()
   test04();
   test05();
   test06();
+  test07();
 }
diff --git a/libstdc++-v3/testsuite/23_containers/flat_multimap/1.cc b/libstdc++-v3/testsuite/23_containers/flat_multimap/1.cc
index ff180bf..79fbc1a 100644
--- a/libstdc++-v3/testsuite/23_containers/flat_multimap/1.cc
+++ b/libstdc++-v3/testsuite/23_containers/flat_multimap/1.cc
@@ -219,6 +219,16 @@ test06()
   VERIFY( std::ranges::equal(m | std::views::values, (int[]){2, 3, 4, 5, 6}) );
 }
 
+void
+test07()
+{
+  // PR libstdc++/119427 - std::erase_if(std::flat_foo) does not work
+  std::flat_multimap<int, int> m = {std::pair{1, 2}, {3, 4}, {3, 3}, {5, 6}, {6, 6}};
+  auto n = std::erase_if(m, [](auto x) { auto [k,v] = x; return k == 1 || v == 6; });
+  VERIFY( n == 3 );
+  VERIFY( std::ranges::equal(m, (std::pair<int,int>[]){{3,4},{3,3}}) );
+}
+
 int
 main()
 {
@@ -231,4 +241,5 @@ main()
   test04();
   test05();
   test06();
+  test07();
 }
diff --git a/libstdc++-v3/testsuite/23_containers/flat_multiset/1.cc b/libstdc++-v3/testsuite/23_containers/flat_multiset/1.cc
index 7d9a33c..63855e0 100644
--- a/libstdc++-v3/testsuite/23_containers/flat_multiset/1.cc
+++ b/libstdc++-v3/testsuite/23_containers/flat_multiset/1.cc
@@ -235,6 +235,16 @@ test08()
   VERIFY( copy_counter == 2 );
 }
 
+void
+test09()
+{
+  // PR libstdc++/119427 - std::erase_if(std::flat_foo) does not work
+  std::flat_multiset<int> s = {1,1,2,2,3,4,5};
+  auto n = std::erase_if(s, [](int x) { return x % 2 != 0; });
+  VERIFY( n == 4 );
+  VERIFY( std::ranges::equal(s, (int[]){2,2,4}) );
+}
+
 int
 main()
 {
@@ -247,4 +257,5 @@ main()
   test06();
   test07();
   test08();
+  test09();
 }
diff --git a/libstdc++-v3/testsuite/23_containers/flat_set/1.cc b/libstdc++-v3/testsuite/23_containers/flat_set/1.cc
index ed24fab..b1d9002 100644
--- a/libstdc++-v3/testsuite/23_containers/flat_set/1.cc
+++ b/libstdc++-v3/testsuite/23_containers/flat_set/1.cc
@@ -248,6 +248,16 @@ test08()
   VERIFY( copy_counter == 1 );
 }
 
+void
+test09()
+{
+  // PR libstdc++/119427 - std::erase_if(std::flat_foo) does not work
+  std::flat_set<int> s = {1,2,3,4,5};
+  auto n = std::erase_if(s, [](int x) { return x % 2 != 0; });
+  VERIFY( n == 3 );
+  VERIFY( std::ranges::equal(s, (int[]){2,4}) );
+}
+
 int
 main()
 {
@@ -260,4 +270,5 @@ main()
   test06();
   test07();
   test08();
+  test09();
 }