PR libstdc++/84928 use std::move in <numeric> algorithms

P0616R0 altered the effects of the <numeric> algorithms to use std::move
on the accumulator values (resolving LWG 2055). This implements the
change for C++2a, but retains the previous behaviour for older
standards.

	* include/bits/stl_numeric.h (_GLIBCXX_MOVE_IF_20): Define macro to
	conditionally move, according to __cplusplus value.
	(accumulate, inner_product, partial_sum, adjacent_difference): Use
	_GLIBCXX_MOVE_IF_20.
	* testsuite/26_numerics/accumulate/lwg2055.cc: New test.
	* testsuite/26_numerics/adjacent_difference/lwg2055.cc: New test.
	* testsuite/26_numerics/inner_product/lwg2055.cc: New test.
	* testsuite/26_numerics/partial_sum/lwg2055.cc: New test.

From-SVN: r262477

libstdc++-v3/ChangeLog

@@ -1,5 +1,15 @@
 2018-07-06  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/84928 use std::move in <numeric> algorithms
+	* include/bits/stl_numeric.h (_GLIBCXX_MOVE_IF_20): Define macro to
+	conditionally move, according to __cplusplus value.
+	(accumulate, inner_product, partial_sum, adjacent_difference): Use
+	_GLIBCXX_MOVE_IF_20.
+	* testsuite/26_numerics/accumulate/lwg2055.cc: New test.
+	* testsuite/26_numerics/adjacent_difference/lwg2055.cc: New test.
+	* testsuite/26_numerics/inner_product/lwg2055.cc: New test.
+	* testsuite/26_numerics/partial_sum/lwg2055.cc: New test.
+
 	* config/abi/pre/gnu.ver: Use wildcards to combine related patterns.
 
 	P0935R0 Eradicating unnecessarily explicit default constructors

libstdc++-v3/include/bits/stl_numeric.h

@@ -104,6 +104,14 @@ namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_ALGO
 
+#if __cplusplus > 201703L
+// _GLIBCXX_RESOLVE_LIB_DEFECTS
+// DR 2055. std::move in std::accumulate and other algorithms
+# define _GLIBCXX_MOVE_IF_20(_E) std::move(_E)
+#else
+# define _GLIBCXX_MOVE_IF_20(_E) _E
+#endif
+
   /**
    *  @brief  Accumulate values in a range.
    *
@@ -124,7 +132,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first, __last);
 
       for (; __first != __last; ++__first)
-	__init = __init + *__first;
+	__init = _GLIBCXX_MOVE_IF_20(__init) + *__first;
       return __init;
     }
 
@@ -151,7 +159,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first, __last);
 
       for (; __first != __last; ++__first)
-	__init = __binary_op(__init, *__first);
+	__init = __binary_op(_GLIBCXX_MOVE_IF_20(__init), *__first);
       return __init;
     }
 
@@ -180,7 +188,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first1, __last1);
 
       for (; __first1 != __last1; ++__first1, (void)++__first2)
-	__init = __init + (*__first1 * *__first2);
+	__init = _GLIBCXX_MOVE_IF_20(__init) + (*__first1 * *__first2);
       return __init;
     }
 
@@ -214,7 +222,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first1, __last1);
 
       for (; __first1 != __last1; ++__first1, (void)++__first2)
-	__init = __binary_op1(__init, __binary_op2(*__first1, *__first2));
+	__init = __binary_op1(_GLIBCXX_MOVE_IF_20(__init),
+			      __binary_op2(*__first1, *__first2));
       return __init;
     }
 
@@ -251,7 +260,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       *__result = __value;
       while (++__first != __last)
 	{
-	  __value = __value + *__first;
+	  __value = _GLIBCXX_MOVE_IF_20(__value) + *__first;
 	  *++__result = __value;
 	}
       return ++__result;
@@ -292,7 +301,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       *__result = __value;
       while (++__first != __last)
 	{
-	  __value = __binary_op(__value, *__first);
+	  __value = __binary_op(_GLIBCXX_MOVE_IF_20(__value), *__first);
 	  *++__result = __value;
 	}
       return ++__result;
@@ -332,7 +341,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       while (++__first != __last)
 	{
 	  _ValueType __tmp = *__first;
-	  *++__result = __tmp - __value;
+	  *++__result = __tmp - _GLIBCXX_MOVE_IF_20(__value);
 	  __value = _GLIBCXX_MOVE(__tmp);
 	}
       return ++__result;
@@ -375,12 +384,14 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       while (++__first != __last)
 	{
 	  _ValueType __tmp = *__first;
-	  *++__result = __binary_op(__tmp, __value);
+	  *++__result = __binary_op(__tmp, _GLIBCXX_MOVE_IF_20(__value));
 	  __value = _GLIBCXX_MOVE(__tmp);
 	}
       return ++__result;
     }
 
+#undef _GLIBCXX_MOVE_IF_20
+
 _GLIBCXX_END_NAMESPACE_ALGO
 } // namespace std
 

libstdc++-v3/testsuite/26_numerics/accumulate/lwg2055.cc

@@ -0,0 +1,93 @@
+// Copyright (C) 2018 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++2a" }
+// { dg-do run { target c++2a } }
+
+#include <numeric>
+#include <iterator>
+#include <testsuite_hooks.h>
+
+struct Int
+{
+  Int(int v) : val(v) { }
+
+  ~Int() = default;
+
+  Int(const Int& x) : val(x.val), copies(x.copies), moved_from(x.moved_from)
+  { ++copies; }
+
+  Int(Int&& x) : val(x.val), copies(x.copies), moved_from(x.moved_from)
+  { x.moved_from = true; }
+
+  Int& operator=(const Int& x)
+  {
+    val = x.val;
+    copies = x.copies + 1;
+    moved_from = x.moved_from;
+    return *this;
+  }
+
+  Int& operator=(Int&& x)
+  {
+    val = x.val;
+    copies = x.copies;
+    moved_from = x.moved_from;
+    x.moved_from = true;
+    return *this;
+  }
+
+  int val = 0;
+  int copies = 0;
+  bool moved_from = false;
+};
+
+Int operator+(Int x, Int y) { x.val += y.val; return x; }
+
+struct Add
+{
+  Int operator()(Int x, Int y) const { x.val += y.val; return x; }
+};
+
+void
+test01()
+{
+  Int i[] = { 0, 1, 2, 3, 4 };
+  Int res = std::accumulate(std::begin(i), std::end(i), Int{0});
+  VERIFY( res.copies == 0 );
+  VERIFY( !res.moved_from );
+  for (const auto& r : i)
+    VERIFY( !r.moved_from );
+}
+
+void
+test02()
+{
+  Int i[] = { 0, 1, 2, 3, 4 };
+  Int res = std::accumulate(std::begin(i), std::end(i), Int{0}, Add{});
+  VERIFY( res.copies == 0 );
+  VERIFY( !res.moved_from );
+  for (const auto& r : i)
+    VERIFY( !r.moved_from );
+}
+
+int
+main()
+{
+  test01();
+  test02();
+}

libstdc++-v3/testsuite/26_numerics/adjacent_difference/lwg2055.cc

@@ -0,0 +1,126 @@
+// Copyright (C) 2018 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++2a" }
+// { dg-do run { target c++2a } }
+
+#include <numeric>
+#include <iterator>
+#include <testsuite_hooks.h>
+
+struct Int
+{
+  Int(int v) : val(v) { }
+
+  ~Int() = default;
+
+  Int(const Int& x) : val(x.val), copies(x.copies), moved_from(x.moved_from)
+  { ++copies; }
+
+  Int(Int&& x) : val(x.val), copies(x.copies), moved_from(x.moved_from)
+  { x.moved_from = true; }
+
+  Int& operator=(const Int& x)
+  {
+    val = x.val;
+    copies = x.copies + 1;
+    moved_from = x.moved_from;
+    return *this;
+  }
+
+  Int& operator=(Int&& x)
+  {
+    val = x.val;
+    copies = x.copies;
+    moved_from = x.moved_from;
+    x.moved_from = true;
+    return *this;
+  }
+
+  int val = 0;
+  int copies = 0;
+  bool moved_from = false;
+};
+
+Int operator-(Int x, Int y) { x.val -= y.val; return x; }
+
+struct Subtract
+{
+  Int operator()(Int x, Int y) const { x.val -= y.val; return x; }
+};
+
+void
+test01()
+{
+  Int i[] = { 0, 1, 2, 3, 4 };
+  std::adjacent_difference(std::begin(i), std::end(i), std::begin(i));
+  for (const auto& r : i)
+  {
+    VERIFY( r.copies == 2 );
+    VERIFY( !r.moved_from );
+  }
+}
+
+void
+test02()
+{
+  Int i[] = { 0, 1, 2, 3, 4 };
+  std::adjacent_difference(std::begin(i), std::end(i), std::begin(i),
+			   Subtract{});
+  for (const auto& r : i)
+  {
+    VERIFY( r.copies == 2 );
+    VERIFY( !r.moved_from );
+  }
+}
+
+void
+test03()
+{
+  Int i[] = { 0, 1, 2, 3, 4 };
+  std::adjacent_difference(std::make_move_iterator(std::begin(i)),
+			   std::make_move_iterator(std::end(i)),
+			   std::begin(i));
+  for (const auto& r : i)
+  {
+    VERIFY( r.copies == 1 );
+    VERIFY( !r.moved_from );
+  }
+}
+
+void
+test04()
+{
+  Int i[] = { 0, 1, 2, 3, 4 };
+  std::adjacent_difference(std::make_move_iterator(std::begin(i)),
+			   std::make_move_iterator(std::end(i)),
+			   std::begin(i), Subtract{});
+  for (const auto& r : i)
+  {
+    VERIFY( r.copies == 1 );
+    VERIFY( !r.moved_from );
+  }
+}
+
+int
+main()
+{
+  test01();
+  test02();
+  test03();
+  test04();
+}

libstdc++-v3/testsuite/26_numerics/inner_product/lwg2055.cc

@@ -0,0 +1,107 @@
+// Copyright (C) 2018 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++2a" }
+// { dg-do run { target c++2a } }
+
+#include <numeric>
+#include <iterator>
+#include <testsuite_hooks.h>
+
+struct Int
+{
+  Int(int v) : val(v) { }
+
+  ~Int() = default;
+
+  Int(const Int& x) : val(x.val), copies(x.copies), moved_from(x.moved_from)
+  { ++copies; }
+
+  Int(Int&& x) : val(x.val), copies(x.copies), moved_from(x.moved_from)
+  { x.moved_from = true; }
+
+  Int& operator=(const Int& x)
+  {
+    val = x.val;
+    copies = x.copies + 1;
+    moved_from = x.moved_from;
+    return *this;
+  }
+
+  Int& operator=(Int&& x)
+  {
+    val = x.val;
+    copies = x.copies;
+    moved_from = x.moved_from;
+    x.moved_from = true;
+    return *this;
+  }
+
+  int val = 0;
+  int copies = 0;
+  bool moved_from = false;
+};
+
+Int operator+(Int x, Int y) { x.val += y.val; return x; }
+Int operator*(Int x, Int y) { x.val *= y.val; return x; }
+
+struct Add
+{
+  Int operator()(Int x, Int y) const { x.val += y.val; return x; }
+};
+
+struct Multiply
+{
+  Int operator()(Int x, Int y) const { x.val *= y.val; return x; }
+};
+
+void
+test01()
+{
+  Int i[] = { 0, 1, 2, 3, 4 };
+  Int j[] = { 5, 6, 7, 8, 9 };
+  Int res = std::inner_product(std::begin(i), std::end(i), std::begin(j),
+			       Int{0});
+  VERIFY( res.copies == 0 );
+  VERIFY( !res.moved_from );
+  for (const auto& r : i)
+    VERIFY( !r.moved_from );
+  for (const auto& r : j)
+    VERIFY( !r.moved_from );
+}
+
+void
+test02()
+{
+  Int i[] = { 0, 1, 2, 3, 4 };
+  Int j[] = { 5, 6, 7, 8, 9 };
+  Int res = std::inner_product(std::begin(i), std::end(i), std::begin(j),
+			       Int{0}, Add{}, Multiply{});
+  VERIFY( res.copies == 0 );
+  VERIFY( !res.moved_from );
+  for (const auto& r : i)
+    VERIFY( !r.moved_from );
+  for (const auto& r : j)
+    VERIFY( !r.moved_from );
+}
+
+int
+main()
+{
+  test01();
+  test02();
+}

libstdc++-v3/testsuite/26_numerics/partial_sum/lwg2055.cc

@@ -0,0 +1,125 @@
+// Copyright (C) 2018 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++2a" }
+// { dg-do run { target c++2a } }
+
+#include <numeric>
+#include <iterator>
+#include <testsuite_hooks.h>
+
+struct Int
+{
+  Int(int v) : val(v) { }
+
+  ~Int() = default;
+
+  Int(const Int& x) : val(x.val), copies(x.copies), moved_from(x.moved_from)
+  { ++copies; }
+
+  Int(Int&& x) : val(x.val), copies(x.copies), moved_from(x.moved_from)
+  { x.moved_from = true; }
+
+  Int& operator=(const Int& x)
+  {
+    val = x.val;
+    copies = x.copies + 1;
+    moved_from = x.moved_from;
+    return *this;
+  }
+
+  Int& operator=(Int&& x)
+  {
+    val = x.val;
+    copies = x.copies;
+    moved_from = x.moved_from;
+    x.moved_from = true;
+    return *this;
+  }
+
+  int val = 0;
+  int copies = 0;
+  bool moved_from = false;
+};
+
+Int operator+(Int x, Int y) { x.val += y.val; return x; }
+
+struct Add
+{
+  Int operator()(Int x, Int y) const { x.val += y.val; return x; }
+};
+
+void
+test01()
+{
+  Int i[] = { 0, 1, 2, 3, 4 };
+  std::partial_sum(std::begin(i), std::end(i), std::begin(i));
+  for (const auto& r : i)
+  {
+    VERIFY( r.copies == 2 );
+    VERIFY( !r.moved_from );
+  }
+}
+
+void
+test02()
+{
+  Int i[] = { 0, 1, 2, 3, 4 };
+  std::partial_sum(std::begin(i), std::end(i), std::begin(i), Add{});
+  for (const auto& r : i)
+  {
+    VERIFY( r.copies == 2 );
+    VERIFY( !r.moved_from );
+  }
+}
+
+void
+test03()
+{
+  Int i[] = { 0, 1, 2, 3, 4 };
+  std::partial_sum(std::make_move_iterator(std::begin(i)),
+		   std::make_move_iterator(std::end(i)),
+		   std::begin(i));
+  for (const auto& r : i)
+  {
+    VERIFY( r.copies == 1 );
+    VERIFY( !r.moved_from );
+  }
+}
+
+void
+test04()
+{
+  Int i[] = { 0, 1, 2, 3, 4 };
+  std::partial_sum(std::make_move_iterator(std::begin(i)),
+		   std::make_move_iterator(std::end(i)),
+		   std::begin(i), Add{});
+  for (const auto& r : i)
+  {
+    VERIFY( r.copies == 1 );
+    VERIFY( !r.moved_from );
+  }
+}
+
+int
+main()
+{
+  test01();
+  test02();
+  test03();
+  test04();
+}