From a9602d56de133730a3d8bc02bd317396000663f1 Mon Sep 17 00:00:00 2001
From: Howard Hinnant <hhinnant@apple.com>
Date: Sat, 29 Jun 2013 23:45:43 +0000
Subject: [PATCH] Prevent '\b' from backing up into invalid memory.  Fixes
 http://llvm.org/bugs/show_bug.cgi?id=16240.  Sorry, I can not think of a good
 test case for this one, except by running valgrind as reported in the bug.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@185273 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/regex | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/include/regex b/include/regex
index 52c9178a..02211672 100644
--- a/include/regex
+++ b/include/regex
@@ -2843,6 +2843,15 @@ private:
                  const basic_regex<_Cp, _Tp>& __e,
                  regex_constants::match_flag_type __flags);
 
+    template <class _Iter, class _Ap, class _Cp, class _Tp>
+    friend
+    bool
+    regex_search(__wrap_iter<_Iter> __first,
+                 __wrap_iter<_Iter> __last,
+                 match_results<__wrap_iter<_Iter>, _Ap>& __m,
+                 const basic_regex<_Cp, _Tp>& __e,
+                 regex_constants::match_flag_type __flags);
+
     template <class, class> friend class __lookahead;
 };
 
@@ -5808,6 +5817,21 @@ regex_search(_BidirectionalIterator __first, _BidirectionalIterator __last,
     return __r;
 }
 
+template <class _Iter, class _Allocator, class _CharT, class _Traits>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+regex_search(__wrap_iter<_Iter> __first,
+             __wrap_iter<_Iter> __last,
+             match_results<__wrap_iter<_Iter>, _Allocator>& __m,
+             const basic_regex<_CharT, _Traits>& __e,
+             regex_constants::match_flag_type __flags = regex_constants::match_default)
+{
+    match_results<const _CharT*> __mc;
+    bool __r = __e.__search(__first.base(), __last.base(), __mc, __flags);
+    __m.__assign(__first, __last, __mc, __flags & regex_constants::__no_update_pos);
+    return __r;
+}
+
 template <class _Allocator, class _CharT, class _Traits>
 inline _LIBCPP_INLINE_VISIBILITY
 bool
@@ -6045,7 +6069,7 @@ regex_iterator<_BidirectionalIterator, _CharT, _Traits>::operator++()
 {
     __flags_ |= regex_constants::__no_update_pos;
     _BidirectionalIterator __start = __match_[0].second;
-    if (__match_.length() == 0)
+    if (__match_.empty())
     {
         if (__start == __end_)
         {