commit 708b86b5f9da418ac7d64d44a09ea5d3b389b354
author Marshall Clow <mclow.lists@gmail.com> Tue Jun 02 13:52:16 2015 +0000
committer Marshall Clow <mclow.lists@gmail.com> Tue Jun 02 13:52:16 2015 +0000
tree 2790589db860b65dc97ffc58ff26cd93613323ef
parent 56523ff60ebfc5aaff8c10ae2c6f5f2dd8c5512c

Fix some places where we could call memmove(null,xxx,0) - which is UB

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@238831 91177308-0d34-0410-b5e6-96231b3b80d8

include/algorithm

diff --git a/include/algorithm b/include/algorithm
index 76f59f2..459071f 100644
--- a/include/algorithm
+++ b/include/algorithm
@@ -1763,7 +1763,8 @@
 __copy(_Tp* __first, _Tp* __last, _Up* __result)
 {
     const size_t __n = static_cast<size_t>(__last - __first);
-    _VSTD::memmove(__result, __first, __n * sizeof(_Up));
+    if (__n > 0)
+        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
     return __result + __n;
 }
 
@@ -1798,8 +1799,11 @@
 __copy_backward(_Tp* __first, _Tp* __last, _Up* __result)
 {
     const size_t __n = static_cast<size_t>(__last - __first);
-    __result -= __n;
-    _VSTD::memmove(__result, __first, __n * sizeof(_Up));
+    if (__n > 0)
+    {
+        __result -= __n;
+        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
+    }
     return __result;
 }
 
@@ -1896,7 +1900,8 @@
 __move(_Tp* __first, _Tp* __last, _Up* __result)
 {
     const size_t __n = static_cast<size_t>(__last - __first);
-    _VSTD::memmove(__result, __first, __n * sizeof(_Up));
+    if (__n > 0)
+        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
     return __result + __n;
 }
 
@@ -1931,8 +1936,11 @@
 __move_backward(_Tp* __first, _Tp* __last, _Up* __result)
 {
     const size_t __n = static_cast<size_t>(__last - __first);
-    __result -= __n;
-    _VSTD::memmove(__result, __first, __n * sizeof(_Up));
+    if (__n > 0)
+    {
+        __result -= __n;
+        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
+    }
     return __result;
 }