Still more P0202 constexpr-ifying. This batch is: for_each/for_each_n/lexicographical_compare

llvm-svn: 323147

1 files changed, 24 insertions, 2 deletions

diff --git a/libcxx/test/std/algorithms/alg.modifying.operations/alg.partitions/partition_copy.pass.cpp b/libcxx/test/std/algorithms/alg.modifying.operations/alg.partitions/partition_copy.pass.cpp
index 67e1cccaf73..0fd24c1c3cb 100644
--- a/libcxx/test/std/algorithms/alg.modifying.operations/alg.partitions/partition_copy.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.modifying.operations/alg.partitions/partition_copy.pass.cpp
@@ -11,7 +11,7 @@
 
 // template <class InputIterator, class OutputIterator1,
 //           class OutputIterator2, class Predicate>
-//     pair<OutputIterator1, OutputIterator2>
+//     constexpr pair<OutputIterator1, OutputIterator2>     // constexpr after C++17
 //     partition_copy(InputIterator first, InputIterator last,
 //                    OutputIterator1 out_true, OutputIterator2 out_false,
 //                    Predicate pred);
@@ -19,13 +19,31 @@
 #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 bool test_constexpr() {
+    int ia[] = {1, 3, 5, 2, 4, 6};
+    int r1[10] = {0};
+    int r2[10] = {0};
+    
+    auto p = std::partition_copy(std::begin(ia), std::end(ia), 
+                    std::begin(r1), std::begin(r2), is_odd());
+
+    return std::all_of(std::begin(r1), p.first, is_odd())
+        && std::all_of(p.first, std::end(r1), [](int a){return a == 0;})
+        && std::none_of(std::begin(r2), p.second, is_odd())
+        && std::all_of(p.second, std::end(r2), [](int a){return a == 0;})
+           ;
+    }
+#endif
+
 int main()
 {
     {
@@ -47,4 +65,8 @@ int main()
         assert(r2[2] == 6);
         assert(r2[3] == 8);
     }
+
+#if TEST_STD_VER > 17
+    static_assert(test_constexpr());
+#endif
 }