From cb9e8bcad80be8e65e3ad6b08d0632c967c982e3 Mon Sep 17 00:00:00 2001
From: "knielsen@ymer.(none)" <>
Date: Mon, 5 Feb 2007 10:50:08 +0100
Subject: [PATCH] Fix false Valgrind warning.

On some compiler/platform combination, an assignment of form *p= *p
would map to a memcpy() call, and Valgrind flags this as an overlapped
memcpy() error.

Fix by prefixing *p= *q with if(p!=q) when building for Valgrind
(HAVE_purify).
---
 sql/sql_select.cc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index dcf1f0cfc79..ea69eb72b51 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -3520,7 +3520,11 @@ update_ref_and_keys(THD *thd, DYNAMIC_ARRAY *keyuse,JOIN_TAB *join_tab,
 	  continue;
       }
 
-      *save_pos= *use;
+#ifdef HAVE_purify
+      /* Valgrind complains about overlapped memcpy when save_pos==use. */
+      if (save_pos != use)
+#endif
+        *save_pos= *use;
       prev=use;
       found_eq_constant= !use->used_tables;
       /* Save ptr to first use */