Fixed BUG#8540: Local variable overrides an alias.

mysql-test/r/sp.result

@@ -2059,6 +2059,16 @@ call bug6029()|
 1136
 drop procedure bug6029|
 drop table t3|
+drop procedure if exists bug8540|
+create procedure bug8540()
+begin
+declare x int default 1;
+select x as y, x+0 as z;
+end|
+call bug8540()|
+y	z
+1	1
+drop procedure bug8540|
 drop table if exists fac|
 create table fac (n int unsigned not null primary key, f bigint unsigned)|
 drop procedure if exists ifac|

mysql-test/t/sp.test

@@ -2520,6 +2520,22 @@ call bug6029()|
 drop procedure bug6029|
 drop table t3|
 
+#
+# BUG#8540: Local variable overrides an alias
+#
+--disable_warnings
+drop procedure if exists bug8540|
+--enable_warnings
+
+create procedure bug8540()
+begin
+  declare x int default 1;
+  select x as y, x+0 as z;
+end|
+
+call bug8540()|
+drop procedure bug8540|
+
 
 #
 # Some "real" examples

sql/item.h

@@ -460,7 +460,10 @@ public:
   {
     Item *it= this_item();
 
-    it->set_name(m_name.str, m_name.length, system_charset_info);
+    if (name)
+      it->set_name(name, strlen(name), system_charset_info);
+    else
+      it->set_name(m_name.str, m_name.length, system_charset_info);
     it->make_field(field);
   }