Reset thd->lex->current_select for SP

current_select may point to data from old parser states
when calling a stored procedure with CALL

The failure happens in Item::Item when testing if we are
in having.

Fixed by explicitely reseting current_select in do_execute_sp()
and in sp_rcontext::create(). The later is also needed for
stored functions().

sql/sp_rcontext.cc

@@ -61,6 +61,7 @@ sp_rcontext *sp_rcontext::create(THD *thd,
                                  const sp_pcontext *root_parsing_ctx,
                                  Field *return_value_fld)
 {
+  SELECT_LEX *save_current_select;
   sp_rcontext *ctx= new (thd->mem_root) sp_rcontext(root_parsing_ctx,
                                                     return_value_fld,
                                                     thd->in_sub_stmt);
@@ -68,14 +69,19 @@ sp_rcontext *sp_rcontext::create(THD *thd,
   if (!ctx)
     return NULL;
 
+  /* Reset current_select as it's checked in Item_ident::Item_ident */
+  save_current_select= thd->lex->current_select;
+  thd->lex->current_select= 0;
+
   if (ctx->alloc_arrays(thd) ||
       ctx->init_var_table(thd) ||
       ctx->init_var_items(thd))
   {
     delete ctx;
-    return NULL;
+    ctx= 0;
   }
 
+  thd->lex->current_select= save_current_select;
   return ctx;
 }
 

sql/sql_parse.cc

@@ -2876,6 +2876,12 @@ static bool do_execute_sp(THD *thd, sp_head *sp)
   ha_rows select_limit= thd->variables.select_limit;
   thd->variables.select_limit= HA_POS_ERROR;
 
+  /*
+    Reset current_select as it may point to random data as a
+    result of previous parsing.
+  */
+  thd->lex->current_select= NULL;
+
   /*
     We never write CALL statements into binlog:
      - If the mode is non-prelocked, each statement will be logged