From: Jonathan Wakely <jwakely@redhat.com>
Date: Sat, 23 May 2020 17:29:33 +0000 (+0100)
Subject: libstdc++: Fix function that can't be constexpr in C++11 (PR 95289)
X-Git-Tag: misc/first-auto-changelog-10~13
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3ba391077d41324f6c0585f0ec76be0f44dd5b43;p=thirdparty%2Fgcc.git

libstdc++: Fix function that can't be constexpr in C++11 (PR 95289)

The body of this function isn't just a return statement, so it can't be
constexpr until C++14.

Backport from mainline
2020-05-23  Jonathan Wakely  <jwakely@redhat.com>

	PR libstdc++/95289
	* include/debug/helper_functions.h (__get_distance): Only declare
	as a constexpr function for C++14 and up.
	* testsuite/25_algorithms/copy/debug/95289.cc: New test.
---

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index f06ebaaa1091..323caae631c6 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,13 @@
+2020-05-23  Jonathan Wakely  <jwakely@redhat.com>
+
+	Backport from mainline
+	2020-05-23  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/95289
+	* include/debug/helper_functions.h (__get_distance): Only declare
+	as a constexpr function for C++14 and up.
+	* testsuite/25_algorithms/copy/debug/95289.cc: New test.
+
 2020-05-21  Jonathan Wakely  <jwakely@redhat.com>
 
 	Backport from mainline
diff --git a/libstdc++-v3/include/debug/helper_functions.h b/libstdc++-v3/include/debug/helper_functions.h
index 251582d59220..62d5309257f2 100644
--- a/libstdc++-v3/include/debug/helper_functions.h
+++ b/libstdc++-v3/include/debug/helper_functions.h
@@ -96,7 +96,7 @@ namespace __gnu_debug
     { return std::make_pair(__rhs - __lhs, __dp_exact); }
 
   template<typename _Iterator>
-    _GLIBCXX_CONSTEXPR
+    _GLIBCXX14_CONSTEXPR
     inline typename _Distance_traits<_Iterator>::__type
     __get_distance(_Iterator __lhs, _Iterator __rhs,
 		   std::input_iterator_tag)
diff --git a/libstdc++-v3/testsuite/25_algorithms/copy/debug/95289.cc b/libstdc++-v3/testsuite/25_algorithms/copy/debug/95289.cc
new file mode 100644
index 000000000000..bcdab19761f3
--- /dev/null
+++ b/libstdc++-v3/testsuite/25_algorithms/copy/debug/95289.cc
@@ -0,0 +1,31 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++11 -D_GLIBCXX_DEBUG" }
+// { dg-do compile { target c++11_only } }
+
+#include <algorithm>
+#include <iterator>
+#include <istream>
+
+// PR libstdc++/95289
+
+void
+test01(std::istream_iterator<char> i, char* out)
+{
+  std::copy(i, decltype(i){}, out);
+}