Fixed BUG#9538: SProc: Creation fails if we try to SET system variable

                  using @@var_name in proc
  Made sure we don't lose the tokenizer state when swapping lex in during SET
  parsing.


mysql-test/r/sp.result:
  New test case for BUG#9538.
mysql-test/t/sp.test:
  New test case for BUG#9538.
sql/sp_head.cc:
  Keep lex->next_state when swapping lex during SP parsing (for SET mainly),
  otherwise the tokenizer gets confused.

mysql-test/r/sp.result

@@ -3079,4 +3079,17 @@ one	1
 delete from t1|
 drop procedure bug9565_sub|
 drop procedure bug9565|
+drop procedure if exists bug9538|
+create procedure bug9538()
+set @@sort_buffer_size = 1000000|
+set @x = @@sort_buffer_size|
+select @@sort_buffer_size|
+@@sort_buffer_size
+262136
+call bug9538()|
+select @@sort_buffer_size|
+@@sort_buffer_size
+1000000
+set @@sort_buffer_size = @x|
+drop procedure bug9538|
 drop table t1,t2;

mysql-test/t/sp.test

@@ -3855,6 +3855,25 @@ drop procedure bug9565_sub|
 drop procedure bug9565|
 
 
+#
+# BUG#9538: SProc: Creation fails if we try to SET system variable
+#           using @@var_name in proc
+#
+--disable_warnings
+drop procedure if exists bug9538|
+--enable_warnings
+create procedure bug9538()
+  set @@sort_buffer_size = 1000000|
+
+set @x = @@sort_buffer_size|
+select @@sort_buffer_size|
+call bug9538()|
+select @@sort_buffer_size|
+set @@sort_buffer_size = @x|
+
+drop procedure bug9538|
+
+
 #
 # BUG#NNNN: New bug synopsis
 #

sql/sp_head.cc

@@ -1023,6 +1023,7 @@ sp_head::reset_lex(THD *thd)
   DBUG_ENTER("sp_head::reset_lex");
   LEX *sublex;
   LEX *oldlex= thd->lex;
+  my_lex_states state= oldlex->next_state; // Keep original next_state
 
   (void)m_lex.push_front(oldlex);
   thd->lex= sublex= new st_lex;
@@ -1030,6 +1031,11 @@ sp_head::reset_lex(THD *thd)
   /* Reset most stuff. The length arguments doesn't matter here. */
   lex_start(thd, oldlex->buf, (ulong) (oldlex->end_of_query - oldlex->ptr));
 
+  /*
+   * next_state is normally the same (0), but it happens that we swap lex in
+   * "mid-sentence", so we must restore it.
+   */
+  sublex->next_state= state;
   /* We must reset ptr and end_of_query again */
   sublex->ptr= oldlex->ptr;
   sublex->end_of_query= oldlex->end_of_query;