Fix std::midpoint(T*, T*) for reversed arguments

Backport from mainline
2019-05-24  Jonathan Wakely  <jwakely@redhat.com>

	* include/std/numeric (midpoint(T*, T*)): Fix incorrect result.
	* testsuite/26_numerics/midpoint/pointer.cc: Change "compile" test
	to "run".

From-SVN: r271609

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 5e3284183b783de58c4af272ce02064b60781768..2a831d41bd1be3d8827f3aad963f7a9f5472b5af 100644 (file)
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,12 @@
 2019-05-24  Jonathan Wakely  <jwakely@redhat.com>
 
+       Backport from mainline
+       2019-05-24  Jonathan Wakely  <jwakely@redhat.com>
+
+       * include/std/numeric (midpoint(T*, T*)): Fix incorrect result.
+       * testsuite/26_numerics/midpoint/pointer.cc: Change "compile" test
+       to "run".
+
        Backport from mainline
        2019-05-17  Jonathan Wakely  <jwakely@redhat.com>
 

diff --git a/libstdc++-v3/include/std/numeric b/libstdc++-v3/include/std/numeric
index 4858ad1aea3a2af25df72b62d0bcb9a666bb50aa..9dff247538ac6c324610ca905d9992d35c412298 100644 (file)
--- a/libstdc++-v3/include/std/numeric
+++ b/libstdc++-v3/include/std/numeric
@@ -195,7 +195,7 @@ template<typename _Tp>
     enable_if_t<__and_v<is_object<_Tp>, bool_constant<sizeof(_Tp) != 0>>, _Tp*>
     midpoint(_Tp* __a, _Tp* __b) noexcept
     {
-      return __a > __b ? __b + (__a - __b) / 2 : __a + (__b - __a) / 2;
+      return __a  + (__b - __a) / 2;
     }
 #endif // C++20
 

diff --git a/libstdc++-v3/testsuite/26_numerics/midpoint/pointer.cc b/libstdc++-v3/testsuite/26_numerics/midpoint/pointer.cc
index bd586d28ba011c890d34648399690bac9dfdadd2..3d3aafc3ec868af9617ba77990de922711ada84f 100644 (file)
--- a/libstdc++-v3/testsuite/26_numerics/midpoint/pointer.cc
+++ b/libstdc++-v3/testsuite/26_numerics/midpoint/pointer.cc
@@ -16,7 +16,7 @@
 // <http://www.gnu.org/licenses/>.
 
 // { dg-options "-std=gnu++2a" }
-// { dg-do compile { target c++2a } }
+// { dg-do run { target c++2a } }
 
 #include <numeric>
 #include <climits>