Merge 10.1 into 10.2

1 files changed, 10 insertions, 1 deletions

diff --git a/sql/sql_string.cc b/sql/sql_string.cc
index 64661f46a49..beff50bd1c5 100644
--- a/sql/sql_string.cc
+++ b/sql/sql_string.cc
@@ -187,7 +187,16 @@ bool String::copy(const char *str,size_t arg_length, CHARSET_INFO *cs)
   if (alloc(arg_length))
     return TRUE;
   DBUG_ASSERT(arg_length < UINT_MAX32);
-  if ((str_length=arg_length))
+  if (Ptr == str && arg_length == uint32(str_length))
+  {
+    /*
+      This can happen in some cases. This code is here mainly to avoid
+      warnings from valgrind, but can also be an indication of error.
+    */
+    DBUG_PRINT("warning", ("Copying string on itself: %p  %zu",
+                           str, arg_length));
+  }
+  else if ((str_length=uint32(arg_length)))
     memcpy(Ptr,str,arg_length);
   Ptr[arg_length]=0;
   str_charset=cs;