PR libstdc++/71500 restore C++11 compatibility in <regex>

	PR libstdc++/71500
	* include/bits/regex_executor.tcc
	(_Backref_matcher<BidIt, regex_traits<C>>::_M_apply): Use
	std::__equal4 instead of C++14 4-iterator overloads of std::equal.
	* include/bits/stl_algobase.h (__equal4): New functions implementing
	4-iterator overloads of std::equal for use in C++11.
	(equal(It1, It1, It2, It2), equal(It1, It1, It2, It2, BinaryPred)):
	Move function bodies to new __equal4 functions.
	* testsuite/28_regex/simple_c++11.cc: New.

From-SVN: r252981

2 files changed, 67 insertions, 47 deletions

diff --git a/libstdc++-v3/include/bits/regex_executor.tcc b/libstdc++-v3/include/bits/regex_executor.tcc
index f6149fe..2ceba35 100644
--- a/libstdc++-v3/include/bits/regex_executor.tcc
+++ b/libstdc++-v3/include/bits/regex_executor.tcc
@@ -366,17 +366,17 @@ namespace __detail
 	       _BiIter __actual_end)
       {
 	if (!_M_icase)
-	  return std::equal(__expected_begin, __expected_end,
-			    __actual_begin, __actual_end);
+	  return std::__equal4(__expected_begin, __expected_end,
+			       __actual_begin, __actual_end);
 	typedef std::ctype<_CharT> __ctype_type;
 	const auto& __fctyp = use_facet<__ctype_type>(_M_traits.getloc());
-	return std::equal(__expected_begin, __expected_end,
-			  __actual_begin, __actual_end,
-			  [this, &__fctyp](_CharT __lhs, _CharT __rhs)
-			  {
-			    return __fctyp.tolower(__lhs)
-				== __fctyp.tolower(__rhs);
-			  });
+	return std::__equal4(__expected_begin, __expected_end,
+			     __actual_begin, __actual_end,
+			     [this, &__fctyp](_CharT __lhs, _CharT __rhs)
+			     {
+			       return __fctyp.tolower(__lhs)
+				 == __fctyp.tolower(__rhs);
+			     });
       }
 
       bool _M_icase;
diff --git a/libstdc++-v3/include/bits/stl_algobase.h b/libstdc++-v3/include/bits/stl_algobase.h
index f68ecb2..a80934c 100644
--- a/libstdc++-v3/include/bits/stl_algobase.h
+++ b/libstdc++-v3/include/bits/stl_algobase.h
@@ -1082,6 +1082,60 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       return true;
     }
 
+#if __cplusplus >= 201103L
+  // 4-iterator version of std::equal<It1, It2> for use in C++11.
+  template<typename _II1, typename _II2>
+    inline bool
+    __equal4(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
+    {
+      using _RATag = random_access_iterator_tag;
+      using _Cat1 = typename iterator_traits<_II1>::iterator_category;
+      using _Cat2 = typename iterator_traits<_II2>::iterator_category;
+      using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
+      if (_RAIters())
+	{
+	  auto __d1 = std::distance(__first1, __last1);
+	  auto __d2 = std::distance(__first2, __last2);
+	  if (__d1 != __d2)
+	    return false;
+	  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2);
+	}
+
+      for (; __first1 != __last1 && __first2 != __last2;
+	  ++__first1, (void)++__first2)
+	if (!(*__first1 == *__first2))
+	  return false;
+      return __first1 == __last1 && __first2 == __last2;
+    }
+
+  // 4-iterator version of std::equal<It1, It2, BinaryPred> for use in C++11.
+  template<typename _II1, typename _II2, typename _BinaryPredicate>
+    inline bool
+    __equal4(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2,
+	     _BinaryPredicate __binary_pred)
+    {
+      using _RATag = random_access_iterator_tag;
+      using _Cat1 = typename iterator_traits<_II1>::iterator_category;
+      using _Cat2 = typename iterator_traits<_II2>::iterator_category;
+      using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
+      if (_RAIters())
+	{
+	  auto __d1 = std::distance(__first1, __last1);
+	  auto __d2 = std::distance(__first2, __last2);
+	  if (__d1 != __d2)
+	    return false;
+	  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2,
+				       __binary_pred);
+	}
+
+      for (; __first1 != __last1 && __first2 != __last2;
+	  ++__first1, (void)++__first2)
+	if (!bool(__binary_pred(*__first1, *__first2)))
+	  return false;
+      return __first1 == __last1 && __first2 == __last2;
+    }
+#endif // C++11
+
 #if __cplusplus > 201103L
 
 #define __cpp_lib_robust_nonmodifying_seq_ops 201304
@@ -1112,24 +1166,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first1, __last1);
       __glibcxx_requires_valid_range(__first2, __last2);
 
-      using _RATag = random_access_iterator_tag;
-      using _Cat1 = typename iterator_traits<_II1>::iterator_category;
-      using _Cat2 = typename iterator_traits<_II2>::iterator_category;
-      using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
-      if (_RAIters())
-	{
-	  auto __d1 = std::distance(__first1, __last1);
-	  auto __d2 = std::distance(__first2, __last2);
-	  if (__d1 != __d2)
-	    return false;
-	  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2);
-	}
-
-      for (; __first1 != __last1 && __first2 != __last2;
-	  ++__first1, (void)++__first2)
-	if (!(*__first1 == *__first2))
-	  return false;
-      return __first1 == __last1 && __first2 == __last2;
+      return _GLIBCXX_STD_A::__equal4(__first1, __last1, __first2, __last2);
     }
 
   /**
@@ -1159,27 +1196,10 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first1, __last1);
       __glibcxx_requires_valid_range(__first2, __last2);
 
-      using _RATag = random_access_iterator_tag;
-      using _Cat1 = typename iterator_traits<_IIter1>::iterator_category;
-      using _Cat2 = typename iterator_traits<_IIter2>::iterator_category;
-      using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
-      if (_RAIters())
-	{
-	  auto __d1 = std::distance(__first1, __last1);
-	  auto __d2 = std::distance(__first2, __last2);
-	  if (__d1 != __d2)
-	    return false;
-	  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2,
-				       __binary_pred);
-	}
-
-      for (; __first1 != __last1 && __first2 != __last2;
-	  ++__first1, (void)++__first2)
-	if (!bool(__binary_pred(*__first1, *__first2)))
-	  return false;
-      return __first1 == __last1 && __first2 == __last2;
+      return _GLIBCXX_STD_A::__equal4(__first1, __last1, __first2, __last2,
+				      __binary_pred);
     }
-#endif
+#endif // C++14
 
   /**
    *  @brief Performs @b dictionary comparison on ranges.