From: Jonathan Wakely <jwakely@redhat.com>
Date: Fri, 24 May 2019 16:09:37 +0000 (+0100)
Subject: Fix std::midpoint(T*, T*) for reversed arguments
X-Git-Tag: releases/gcc-9.2.0~322
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=75addbfa7fb2f6d8e3b99786eea8a56d57f72475;p=thirdparty%2Fgcc.git

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 5e3284183b78..2a831d41bd1b 100644
--- 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 4858ad1aea3a..9dff247538ac 100644
--- 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 bd586d28ba01..3d3aafc3ec86 100644
--- 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>