partition_point gets the P0202 treatment

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@322493 91177308-0d34-0410-b5e6-96231b3b80d8

include/algorithm

@@ -321,7 +321,7 @@ template <class ForwardIterator, class Predicate>
     stable_partition(ForwardIterator first, ForwardIterator last, Predicate pred);
 
 template<class ForwardIterator, class Predicate>
-    ForwardIterator
+    ForwardIterator  // constexpr in C++20
     partition_point(ForwardIterator first, ForwardIterator last, Predicate pred);
 
 template <class ForwardIterator>
@@ -3328,7 +3328,7 @@ partition_copy(_InputIterator __first, _InputIterator __last,
 // partition_point
 
 template<class _ForwardIterator, class _Predicate>
-_ForwardIterator
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
 partition_point(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
 {
     typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;

test/std/algorithms/alg.modifying.operations/alg.partitions/partition_point.pass.cpp

@@ -10,19 +10,32 @@
 // <algorithm>
 
 // template<class ForwardIterator, class Predicate>
-//     ForwardIterator
+//     constpexr ForwardIterator       // constexpr after C++17
 //     partition_point(ForwardIterator first, ForwardIterator last, Predicate pred);
 
 #include <algorithm>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 struct is_odd
 {
-    bool operator()(const int& i) const {return i & 1;}
+    TEST_CONSTEXPR bool operator()(const int& i) const {return i & 1;}
 };
 
+
+#if TEST_STD_VER > 17
+TEST_CONSTEXPR int test_constexpr() {
+    int ia[] = {1, 3, 5, 2, 4, 6};
+    int ib[] = {1, 2, 3, 4, 5, 6};
+    return    (std::partition_point(std::begin(ia), std::end(ia), is_odd()) == ia+3)
+           && (std::partition_point(std::begin(ib), std::end(ib), is_odd()) == ib+1)
+           ;
+    }
+#endif
+
+
 int main()
 {
     {
@@ -73,4 +86,8 @@ int main()
                                     forward_iterator<const int*>(std::begin(ia)),
                                     is_odd()) == forward_iterator<const int*>(ia));
     }
+
+#if TEST_STD_VER > 17
+    static_assert(test_constexpr());
+#endif
 }

test/std/algorithms/alg.nonmodifying/alg.all_of/all_of.pass.cpp

@@ -10,7 +10,7 @@
 // <algorithm>
 
 // template <class InputIterator, class Predicate>
-//   bool
+//     constpexr bool       // constexpr after C++17
 //   all_of(InputIterator first, InputIterator last, Predicate pred);
 
 #include <algorithm>

test/std/algorithms/alg.nonmodifying/alg.any_of/any_of.pass.cpp

@@ -10,7 +10,7 @@
 // <algorithm>
 
 // template <class InputIterator, class Predicate>
-//   bool
+//     constpexr bool       // constexpr after C++17
 //   any_of(InputIterator first, InputIterator last, Predicate pred);
 
 #include <algorithm>