This patch makes swap functions constexpr. Both swap overloads, swap_ranges and iter_swap are updated (with tests).

llvm-svn: 365238

2 files changed, 33 insertions, 0 deletions

diff --git a/libcxx/test/std/algorithms/alg.modifying.operations/alg.swap/iter_swap.pass.cpp b/libcxx/test/std/algorithms/alg.modifying.operations/alg.swap/iter_swap.pass.cpp
index 2fbd905e5be..b3a9f5fc259 100644
--- a/libcxx/test/std/algorithms/alg.modifying.operations/alg.swap/iter_swap.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.modifying.operations/alg.swap/iter_swap.pass.cpp
@@ -18,6 +18,16 @@
 
 #include "test_macros.h"
 
+#if TEST_STD_VER > 17
+constexpr bool test_swap_constexpr()
+{
+    int i = 1;
+    int j = 2;
+    std::iter_swap(&i, &j);
+    return i == 2 && j == 1;
+}
+#endif // TEST_STD_VER > 17
+
 int main(int, char**)
 {
     int i = 1;
@@ -26,5 +36,9 @@ int main(int, char**)
     assert(i == 2);
     assert(j == 1);
 
+#if TEST_STD_VER > 17
+    static_assert(test_swap_constexpr());
+#endif // TEST_STD_VER > 17
+
   return 0;
 }
diff --git a/libcxx/test/std/algorithms/alg.modifying.operations/alg.swap/swap_ranges.pass.cpp b/libcxx/test/std/algorithms/alg.modifying.operations/alg.swap/swap_ranges.pass.cpp
index a47bbd24d95..51671a060d6 100644
--- a/libcxx/test/std/algorithms/alg.modifying.operations/alg.swap/swap_ranges.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.modifying.operations/alg.swap/swap_ranges.pass.cpp
@@ -105,6 +105,21 @@ void test2()
     }
 }
 
+#if TEST_STD_VER > 17
+constexpr bool test_swap_constexpr()
+{
+    int i[3] = {1, 2, 3};
+    int j[3] = {4, 5, 6};
+    std::swap_ranges(i, i+3, j);
+    return i[0] == 4 &&
+           i[1] == 5 &&
+           i[2] == 6 &&
+           j[0] == 1 &&
+           j[1] == 2 &&
+           j[2] == 3;
+}
+#endif // TEST_STD_VER > 17
+
 int main(int, char**)
 {
     test<forward_iterator<int*>, forward_iterator<int*> >();
@@ -149,6 +164,10 @@ int main(int, char**)
     test1<std::unique_ptr<int>*, std::unique_ptr<int>*>();
 #endif // TEST_STD_VER >= 11
 
+#if TEST_STD_VER > 17
+    static_assert(test_swap_constexpr());
+#endif // TEST_STD_VER > 17
+
     test2();
 
   return 0;