Make forward_list::remove/remove_if/unique all return void before C++20; undoes that bit of D58332. Thanks to Mikhail Maltsev for pointing this out

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@365290 91177308-0d34-0410-b5e6-96231b3b80d8

include/forward_list

@@ -120,10 +120,12 @@ public:
                       const_iterator first, const_iterator last);
     void splice_after(const_iterator p, forward_list&& x,
                       const_iterator first, const_iterator last);
-    size_type remove(const value_type& v);
-    template <class Predicate> size_type remove_if(Predicate pred);
-    size_type unique();
-    template <class BinaryPredicate> size_type unique(BinaryPredicate binary_pred);
+    size_type remove(const value_type& v);           // void before C++20
+    template <class Predicate>
+      size_type remove_if(Predicate pred);           // void before C++20
+    size_type unique();                              // void before C++20
+    template <class BinaryPredicate>
+      size_type unique(BinaryPredicate binary_pred); // void before C++20
     void merge(forward_list& x);
     void merge(forward_list&& x);
     template <class Compare> void merge(forward_list& x, Compare comp);
@@ -647,6 +649,11 @@ public:
 
     typedef typename base::iterator       iterator;
     typedef typename base::const_iterator const_iterator;
+#if _LIBCPP_STD_VER > 17
+    typedef size_type                                __remove_return_type;
+#else
+    typedef void                                     __remove_return_type;
+#endif
 
     _LIBCPP_INLINE_VISIBILITY
     forward_list()
@@ -819,11 +826,11 @@ public:
     void splice_after(const_iterator __p, forward_list& __x, const_iterator __i);
     void splice_after(const_iterator __p, forward_list& __x,
                       const_iterator __f, const_iterator __l);
-    size_type remove(const value_type& __v);
-    template <class _Predicate> size_type remove_if(_Predicate __pred);
+    __remove_return_type remove(const value_type& __v);
+    template <class _Predicate> __remove_return_type remove_if(_Predicate __pred);
     _LIBCPP_INLINE_VISIBILITY
-    size_type unique() {return unique(__equal_to<value_type>());}
-    template <class _BinaryPredicate> size_type unique(_BinaryPredicate __binary_pred);
+    __remove_return_type unique() {return unique(__equal_to<value_type>());}
+    template <class _BinaryPredicate> __remove_return_type unique(_BinaryPredicate __binary_pred);
 #ifndef _LIBCPP_CXX03_LANG
     _LIBCPP_INLINE_VISIBILITY
     void merge(forward_list&& __x) {merge(__x, __less<value_type>());}
@@ -1496,7 +1503,7 @@ forward_list<_Tp, _Alloc>::splice_after(const_iterator __p,
 }
 
 template <class _Tp, class _Alloc>
-typename forward_list<_Tp, _Alloc>::size_type
+typename forward_list<_Tp, _Alloc>::__remove_return_type
 forward_list<_Tp, _Alloc>::remove(const value_type& __v)
 {
     forward_list<_Tp, _Alloc> __deleted_nodes(get_allocator()); // collect the nodes we're removing
@@ -1519,12 +1526,12 @@ forward_list<_Tp, _Alloc>::remove(const value_type& __v)
             ++__i;
     }
     
-    return __count_removed;
+    return (__remove_return_type) __count_removed;
 }
 
 template <class _Tp, class _Alloc>
 template <class _Predicate>
-typename forward_list<_Tp, _Alloc>::size_type
+typename forward_list<_Tp, _Alloc>::__remove_return_type
 forward_list<_Tp, _Alloc>::remove_if(_Predicate __pred)
 {
     forward_list<_Tp, _Alloc> __deleted_nodes(get_allocator()); // collect the nodes we're removing
@@ -1547,12 +1554,12 @@ forward_list<_Tp, _Alloc>::remove_if(_Predicate __pred)
             ++__i;
     }
     
-    return __count_removed;
+    return (__remove_return_type) __count_removed;
 }
 
 template <class _Tp, class _Alloc>
 template <class _BinaryPredicate>
-typename forward_list<_Tp, _Alloc>::size_type
+typename forward_list<_Tp, _Alloc>::__remove_return_type
 forward_list<_Tp, _Alloc>::unique(_BinaryPredicate __binary_pred)
 {
     forward_list<_Tp, _Alloc> __deleted_nodes(get_allocator()); // collect the nodes we're removing
@@ -1567,7 +1574,7 @@ forward_list<_Tp, _Alloc>::unique(_BinaryPredicate __binary_pred)
         __i = __j;
     }
     
-    return __count_removed;
+    return (__remove_return_type) __count_removed;
 }
 
 template <class _Tp, class _Alloc>

include/list

@@ -129,11 +129,12 @@ public:
     void splice(const_iterator position, list&& x, const_iterator first,
                                                   const_iterator last);
 
-    size_type remove(const value_type& value); // void before C++20
-    template <class Pred> size_type remove_if(Pred pred); // void before C++20
-    size_type unique();  // void before C++20
+    size_type remove(const value_type& value);       // void before C++20
+    template <class Pred>
+      size_type remove_if(Pred pred);                // void before C++20
+    size_type unique();                              // void before C++20
     template <class BinaryPredicate>
-        size_type unique(BinaryPredicate binary_pred); // void before C++20
+      size_type unique(BinaryPredicate binary_pred); // void before C++20
     void merge(list& x);
     void merge(list&& x);
     template <class Compare>
@@ -858,9 +859,9 @@ public:
     typedef _VSTD::reverse_iterator<iterator>         reverse_iterator;
     typedef _VSTD::reverse_iterator<const_iterator>   const_reverse_iterator;
 #if _LIBCPP_STD_VER > 17
-	typedef size_type                                __remove_return_type;
+    typedef size_type                                __remove_return_type;
 #else
-	typedef void                                     __remove_return_type;
+    typedef void                                     __remove_return_type;
 #endif
 
     _LIBCPP_INLINE_VISIBILITY

test/std/containers/sequences/forwardlist/forwardlist.ops/remove.pass.cpp

@@ -8,7 +8,8 @@
 
 // <forward_list>
 
-// void remove(const value_type& v);
+// void remove(const value_type& v);      // C++17 and before
+// size_type remove(const value_type& v); // C++20 and after
 
 #include <forward_list>
 #include <iterator>
@@ -17,6 +18,21 @@
 #include "test_macros.h"
 #include "min_allocator.h"
 
+template <class L>
+void do_remove(L &l, const typename L::value_type &value, typename L::size_type expected)
+{
+    typename L::size_type old_size = std::distance(l.begin(), l.end());
+#if TEST_STD_VER > 17
+    ASSERT_SAME_TYPE(decltype(l.remove(value)), typename L::size_type);
+    assert(l.remove(value) == expected);
+#else
+    ASSERT_SAME_TYPE(decltype(l.remove(value)), void);
+    l.remove(value);
+#endif
+    assert(old_size - std::distance(l.begin(), l.end()) == expected);
+}
+
+
 struct S {
     S(int i) : i_(new int(i)) {}
     S(const S &rhs) : i_(new int(*rhs.i_)) {}
@@ -37,7 +53,7 @@ int main(int, char**)
         const T t2[] = {5, 5, 5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.remove(0) == 4);
+        do_remove(c1, 0, 4);
         assert(c1 == c2);
     }
     {
@@ -46,7 +62,7 @@ int main(int, char**)
         const T t1[] = {0, 0, 0, 0};
         C c1(std::begin(t1), std::end(t1));
         C c2;
-        assert(c1.remove(0) == 4);
+        do_remove(c1, 0, 4);
         assert(c1 == c2);
     }
     {
@@ -56,7 +72,7 @@ int main(int, char**)
         const T t2[] = {5, 5, 5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.remove(0) == 0);
+        do_remove(c1, 0, 0);
         assert(c1 == c2);
     }
     {
@@ -64,7 +80,7 @@ int main(int, char**)
         typedef std::forward_list<T> C;
         C c1;
         C c2;
-        assert(c1.remove(0) == 0);
+        do_remove(c1, 0, 0);
         assert(c1 == c2);
     }
     {
@@ -74,7 +90,7 @@ int main(int, char**)
         const T t2[] = {5, 5, 5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.remove(0) == 1);
+        do_remove(c1, 0, 1);
         assert(c1 == c2);
     }
     {  // LWG issue #526
@@ -84,7 +100,7 @@ int main(int, char**)
     int t2[] = {   2,    3, 5, 8, 11};
     C c1(std::begin(t1), std::end(t1));
     C c2(std::begin(t2), std::end(t2));
-    assert(c1.remove(c1.front()) == 2);
+    do_remove(c1, c1.front(), 2);
     assert(c1 == c2);
     }
     {
@@ -95,7 +111,7 @@ int main(int, char**)
     C c;
     for(int *ip = std::end(t1); ip != std::begin(t1);)
         c.push_front(S(*--ip));
-    assert(c.remove(c.front()) == 3);
+    do_remove(c, c.front(), 3);
     C::const_iterator it = c.begin();
     for(int *ip = std::begin(t2); ip != std::end(t2); ++ip, ++it) {
         assert ( it != c.end());
@@ -111,7 +127,7 @@ int main(int, char**)
         const T t2[] = {5, 5, 5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.remove(0) == 4);
+        do_remove(c1, 0, 4);
         assert(c1 == c2);
     }
     {
@@ -120,7 +136,7 @@ int main(int, char**)
         const T t1[] = {0, 0, 0, 0};
         C c1(std::begin(t1), std::end(t1));
         C c2;
-        assert(c1.remove(0) == 4);
+        do_remove(c1, 0, 4);
         assert(c1 == c2);
     }
     {
@@ -130,7 +146,7 @@ int main(int, char**)
         const T t2[] = {5, 5, 5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.remove(0) == 0);
+        do_remove(c1, 0, 0);
         assert(c1 == c2);
     }
     {
@@ -138,7 +154,7 @@ int main(int, char**)
         typedef std::forward_list<T, min_allocator<T>> C;
         C c1;
         C c2;
-        assert(c1.remove(0) == 0);
+        do_remove(c1, 0, 0);
         assert(c1 == c2);
     }
     {
@@ -148,7 +164,7 @@ int main(int, char**)
         const T t2[] = {5, 5, 5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.remove(0) == 1);
+        do_remove(c1, 0, 1);
         assert(c1 == c2);
     }
 #endif

test/std/containers/sequences/forwardlist/forwardlist.ops/remove_if.pass.cpp

@@ -8,7 +8,8 @@
 
 // <forward_list>
 
-// template <class Predicate> void remove_if(Predicate pred);
+// template <class Predicate> void      remove_if(Predicate pred); // C++17 and before
+// template <class Predicate> size_type remove_if(Predicate pred); // C++20 and after
 
 #include <forward_list>
 #include <iterator>
@@ -20,15 +21,29 @@
 #include "counting_predicates.hpp"
 
 
+template <class L, class Predicate>
+void do_remove_if(L &l, Predicate pred, typename L::size_type expected)
+{
+    typename L::size_type old_size = std::distance(l.begin(), l.end());
+#if TEST_STD_VER > 17
+    ASSERT_SAME_TYPE(decltype(l.remove_if(pred)), typename L::size_type);
+    assert(l.remove_if(pred) == expected);
+#else
+    ASSERT_SAME_TYPE(decltype(l.remove_if(pred)), void);
+    l.remove_if(pred);
+#endif
+    assert(old_size - std::distance(l.begin(), l.end()) == expected);
+}
+
 bool g(int i)
 {
     return i < 3;
 }
 
-struct PredLWG529 {
-    PredLWG529 (int i) : i_(i) {};
-    ~PredLWG529() { i_ = -32767; }
-    bool operator() (const PredLWG529 &p) const { return p.i_ == i_; }
+struct PredLWG526 {
+    PredLWG526 (int i) : i_(i) {};
+    ~PredLWG526() { i_ = -32767; }
+    bool operator() (const PredLWG526 &p) const { return p.i_ == i_; }
 
     bool operator==(int i) const { return i == i_;}
     int i_;
@@ -45,7 +60,7 @@ int main(int, char**)
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
         Predicate cp(g);
-        assert(c1.remove_if(std::ref(cp)) == 4);
+        do_remove_if(c1, std::ref(cp), 4);
         assert(c1 == c2);
         assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
     }
@@ -57,7 +72,7 @@ int main(int, char**)
         C c1(std::begin(t1), std::end(t1));
         C c2;
         Predicate cp(g);
-        assert(c1.remove_if(std::ref(cp)) == 4);
+        do_remove_if(c1, std::ref(cp), 4);
         assert(c1 == c2);
         assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
     }
@@ -70,7 +85,7 @@ int main(int, char**)
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
         Predicate cp(g);
-        assert(c1.remove_if(std::ref(cp)) == 0);
+        do_remove_if(c1, std::ref(cp), 0);
         assert(c1 == c2);
         assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
     }
@@ -81,7 +96,7 @@ int main(int, char**)
         C c1;
         C c2;
         Predicate cp(g);
-        assert(c1.remove_if(std::ref(cp)) == 0);
+        do_remove_if(c1, std::ref(cp), 0);
         assert(c1 == c2);
         assert(cp.count() == 0);
     }
@@ -94,7 +109,7 @@ int main(int, char**)
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
         Predicate cp(g);
-        assert(c1.remove_if(std::ref(cp)) == 1);
+        do_remove_if(c1, std::ref(cp), 1);
         assert(c1 == c2);
         assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
     }
@@ -102,8 +117,8 @@ int main(int, char**)
     { // LWG issue #526
     int a1[] = {1, 2, 1, 3, 5, 8, 11};
     int a2[] = {   2,    3, 5, 8, 11};
-    std::forward_list<PredLWG529> c(a1, a1 + 7);
-    c.remove_if(std::ref(c.front()));
+    std::forward_list<PredLWG526> c(a1, a1 + 7);
+    do_remove_if(c, std::ref(c.front()), 2);
     for (size_t i = 0; i < 5; ++i)
     {
         assert(!c.empty());
@@ -123,7 +138,7 @@ int main(int, char**)
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
         Predicate cp(g);
-        assert(c1.remove_if(std::ref(cp)) == 4);
+        do_remove_if(c1, std::ref(cp), 4);
         assert(c1 == c2);
         assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
     }
@@ -135,7 +150,7 @@ int main(int, char**)
         C c1(std::begin(t1), std::end(t1));
         C c2;
         Predicate cp(g);
-        assert(c1.remove_if(std::ref(cp)) == 4);
+        do_remove_if(c1, std::ref(cp), 4);
         assert(c1 == c2);
         assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
     }
@@ -148,7 +163,7 @@ int main(int, char**)
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
         Predicate cp(g);
-        assert(c1.remove_if(std::ref(cp)) == 0);
+        do_remove_if(c1, std::ref(cp), 0);
         assert(c1 == c2);
         assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
     }
@@ -159,7 +174,7 @@ int main(int, char**)
         C c1;
         C c2;
         Predicate cp(g);
-        assert(c1.remove_if(std::ref(cp)) == 0);
+        do_remove_if(c1, std::ref(cp), 0);
         assert(c1 == c2);
         assert(cp.count() == 0);
     }
@@ -172,7 +187,7 @@ int main(int, char**)
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
         Predicate cp(g);
-        assert(c1.remove_if(std::ref(cp)) == 1);
+        do_remove_if(c1, std::ref(cp), 1);
         assert(c1 == c2);
         assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
     }

test/std/containers/sequences/forwardlist/forwardlist.ops/unique.pass.cpp

@@ -8,7 +8,8 @@
 
 // <forward_list>
 
-// void unique();
+// void unique();      // C++17 and before
+// size_type unique(); // C++20 and after
 
 #include <forward_list>
 #include <iterator>
@@ -17,6 +18,20 @@
 #include "test_macros.h"
 #include "min_allocator.h"
 
+template <class L>
+void do_unique(L &l, typename L::size_type expected)
+{
+    typename L::size_type old_size = std::distance(l.begin(), l.end());
+#if TEST_STD_VER > 17
+    ASSERT_SAME_TYPE(decltype(l.unique()), typename L::size_type);
+    assert(l.unique() == expected);
+#else
+    ASSERT_SAME_TYPE(decltype(l.unique()), void);
+    l.unique();
+#endif
+    assert(old_size - std::distance(l.begin(), l.end()) == expected);
+}
+
 int main(int, char**)
 {
     {
@@ -26,7 +41,7 @@ int main(int, char**)
         const T t2[] = {0, 5, 0, 5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.unique() == 3);
+        do_unique(c1, 3);
         assert(c1 == c2);
     }
     {
@@ -36,7 +51,7 @@ int main(int, char**)
         const T t2[] = {0};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.unique() == 3);
+        do_unique(c1, 3);
         assert(c1 == c2);
     }
     {
@@ -46,7 +61,7 @@ int main(int, char**)
         const T t2[] = {5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.unique() == 2);
+        do_unique(c1, 2);
         assert(c1 == c2);
     }
     {
@@ -54,7 +69,7 @@ int main(int, char**)
         typedef std::forward_list<T> C;
         C c1;
         C c2;
-        assert(c1.unique() == 0);
+        do_unique(c1, 0);
         assert(c1 == c2);
     }
     {
@@ -64,7 +79,7 @@ int main(int, char**)
         const T t2[] = {5, 0};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.unique() == 2);
+        do_unique(c1, 2);
         assert(c1 == c2);
     }
 #if TEST_STD_VER >= 11
@@ -75,7 +90,7 @@ int main(int, char**)
         const T t2[] = {0, 5, 0, 5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.unique() == 3);
+        do_unique(c1, 3);
         assert(c1 == c2);
     }
     {
@@ -85,7 +100,7 @@ int main(int, char**)
         const T t2[] = {0};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.unique() == 3);
+        do_unique(c1, 3);
         assert(c1 == c2);
     }
     {
@@ -95,7 +110,7 @@ int main(int, char**)
         const T t2[] = {5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.unique() == 2);
+        do_unique(c1, 2);
         assert(c1 == c2);
     }
     {
@@ -103,7 +118,7 @@ int main(int, char**)
         typedef std::forward_list<T, min_allocator<T>> C;
         C c1;
         C c2;
-        assert(c1.unique() == 0);
+        do_unique(c1, 0);
         assert(c1 == c2);
     }
     {
@@ -113,7 +128,7 @@ int main(int, char**)
         const T t2[] = {5, 0};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        assert(c1.unique() == 2);
+        do_unique(c1, 2);
         assert(c1 == c2);
     }
 #endif

test/std/containers/sequences/forwardlist/forwardlist.ops/unique_pred.pass.cpp

@@ -8,7 +8,8 @@
 
 // <forward_list>
 
-// template <class BinaryPredicate> void unique(BinaryPredicate binary_pred);
+// template <class BinaryPredicate> void unique(BinaryPredicate binary_pred);      // C++17 and before
+// template <class BinaryPredicate> size_type unique(BinaryPredicate binary_pred); // C++20 and after
 
 #include <forward_list>
 #include <iterator>
@@ -17,10 +18,25 @@
 #include "test_macros.h"
 #include "min_allocator.h"
 
-struct PredLWG529 {
-    PredLWG529 (int i) : i_(i) {};
-    ~PredLWG529() { i_ = -32767; }
-    bool operator() (const PredLWG529 &lhs, const PredLWG529 &rhs) const { return lhs.i_ == rhs.i_; }
+template <class L, class Predicate>
+void do_unique(L &l, Predicate pred, typename L::size_type expected)
+{
+    typename L::size_type old_size = std::distance(l.begin(), l.end());
+#if TEST_STD_VER > 17
+    ASSERT_SAME_TYPE(decltype(l.unique(pred)), typename L::size_type);
+    assert(l.unique(pred) == expected);
+#else
+    ASSERT_SAME_TYPE(decltype(l.unique(pred)), void);
+    l.unique(pred);
+#endif
+    assert(old_size - std::distance(l.begin(), l.end()) == expected);
+}
+
+
+struct PredLWG526 {
+    PredLWG526 (int i) : i_(i) {};
+    ~PredLWG526() { i_ = -32767; }
+    bool operator() (const PredLWG526 &lhs, const PredLWG526 &rhs) const { return lhs.i_ == rhs.i_; }
 
     bool operator==(int i) const { return i == i_;}
     int i_;
@@ -41,7 +57,7 @@ int main(int, char**)
         const T t2[] = {0, 5, 0, 5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        c1.unique(g);
+        do_unique(c1, g, 3);
         assert(c1 == c2);
     }
     {
@@ -51,7 +67,7 @@ int main(int, char**)
         const T t2[] = {0};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        c1.unique(g);
+        do_unique(c1, g, 3);
         assert(c1 == c2);
     }
     {
@@ -61,7 +77,7 @@ int main(int, char**)
         const T t2[] = {5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        c1.unique(g);
+        do_unique(c1, g, 2);
         assert(c1 == c2);
     }
     {
@@ -69,7 +85,7 @@ int main(int, char**)
         typedef std::forward_list<T> C;
         C c1;
         C c2;
-        c1.unique(g);
+        do_unique(c1, g, 0);
         assert(c1 == c2);
     }
     {
@@ -79,22 +95,22 @@ int main(int, char**)
         const T t2[] = {5, 0};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        c1.unique(g);
+        do_unique(c1, g, 2);
         assert(c1 == c2);
     }
 
     { // LWG issue #526
     int a1[] = {1, 1, 1, 2, 3, 5, 2, 11};
     int a2[] = {1,       2, 3, 5, 2, 11};
-    std::forward_list<PredLWG529> c(a1, a1 + 8);
-    c.unique(std::ref(c.front()));
+    std::forward_list<PredLWG526> c1(a1, a1 + 8);
+    do_unique(c1, std::ref(c1.front()), 2);
     for (size_t i = 0; i < 6; ++i)
     {
-        assert(!c.empty());
-        assert(c.front() == a2[i]);
-        c.pop_front();
+        assert(!c1.empty());
+        assert(c1.front() == a2[i]);
+        c1.pop_front();
     }
-    assert(c.empty());
+    assert(c1.empty());
     }
 
 #if TEST_STD_VER >= 11
@@ -105,7 +121,7 @@ int main(int, char**)
         const T t2[] = {0, 5, 0, 5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        c1.unique(g);
+        do_unique(c1, g, 3);
         assert(c1 == c2);
     }
     {
@@ -115,7 +131,7 @@ int main(int, char**)
         const T t2[] = {0};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        c1.unique(g);
+        do_unique(c1, g, 3);
         assert(c1 == c2);
     }
     {
@@ -125,7 +141,7 @@ int main(int, char**)
         const T t2[] = {5};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        c1.unique(g);
+        do_unique(c1, g, 2);
         assert(c1 == c2);
     }
     {
@@ -133,7 +149,7 @@ int main(int, char**)
         typedef std::forward_list<T, min_allocator<T>> C;
         C c1;
         C c2;
-        c1.unique(g);
+        do_unique(c1, g, 0);
         assert(c1 == c2);
     }
     {
@@ -143,7 +159,7 @@ int main(int, char**)
         const T t2[] = {5, 0};
         C c1(std::begin(t1), std::end(t1));
         C c2(std::begin(t2), std::end(t2));
-        c1.unique(g);
+        do_unique(c1, g, 2);
         assert(c1 == c2);
     }
 #endif