Post-pushbuild corrections for fix of bug #21698.

mysql-test/r/func_str.result

@@ -1136,12 +1136,12 @@ ALTER TABLE t1 ADD INDEX (code);
 CREATE TABLE t2 (id varchar(10) PRIMARY KEY);
 INSERT INTO t2 VALUES ('a11'), ('a12'), ('a13'), ('a14');
 SELECT * FROM t1 INNER JOIN t2 ON t1.code=t2.id 
-WHERE t2.id='a12' AND (code < 'a00' OR LENGTH(code)=5);
+WHERE t2.id='a12' AND (LENGTH(code)=5 OR code < 'a00');
 code	id
 A12  	a12
 EXPLAIN EXTENDED 
 SELECT * FROM t1 INNER JOIN t2 ON code=id 
-WHERE id='a12' AND (code < 'a00' OR LENGTH(code)=5);
+WHERE id='a12' AND (LENGTH(code)=5 OR code < 'a00');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ref	code	code	13	const	3	Using where; Using index
 1	SIMPLE	t2	ref	PRIMARY	PRIMARY	12	const	1	Using where; Using index

mysql-test/t/func_str.test

@@ -773,10 +773,10 @@ CREATE TABLE t2 (id varchar(10) PRIMARY KEY);
 INSERT INTO t2 VALUES ('a11'), ('a12'), ('a13'), ('a14');
 
 SELECT * FROM t1 INNER JOIN t2 ON t1.code=t2.id 
-  WHERE t2.id='a12' AND (code < 'a00' OR LENGTH(code)=5);
+  WHERE t2.id='a12' AND (LENGTH(code)=5 OR code < 'a00');
 EXPLAIN EXTENDED 
 SELECT * FROM t1 INNER JOIN t2 ON code=id 
-  WHERE id='a12' AND (code < 'a00' OR LENGTH(code)=5);
+  WHERE id='a12' AND (LENGTH(code)=5 OR code < 'a00');
 
 DROP TABLE t1,t2;
 

sql/item.h

@@ -411,6 +411,17 @@ public:
 
 
 typedef bool (Item::*Item_processor) (byte *arg);
+/*
+  Analyzer function
+    SYNOPSIS
+      argp   in/out IN:  Analysis parameter
+                    OUT: Parameter to be passed to the transformer
+
+    RETURN 
+      TRUE   Invoke the transformer
+      FALSE  Don't do it
+
+*/
 typedef bool (Item::*Item_analyzer) (byte **argp);
 typedef Item* (Item::*Item_transformer) (byte *arg);
 typedef void (*Cond_traverser) (const Item *item, void *arg);
@@ -740,6 +751,22 @@ public:
     return (this->*transformer)(arg);
   }
 
+  /*
+    This function performs a generic "compilation" of the Item tree.
+    The process of compilation is assumed to go as follows: 
+    
+    compile()
+    { 
+      if (this->*some_analyzer(...))
+      {
+        compile children if any;
+        this->*some_transformer(...);
+      }
+    }
+
+    i.e. analysis is performed top-down while transformation is done
+    bottom-up.      
+  */
   virtual Item* compile(Item_analyzer analyzer, byte **arg_p,
                         Item_transformer transformer, byte *arg_t)
   {

sql/item_cmpfunc.cc

@@ -2811,7 +2811,6 @@ Item *Item_cond::compile(Item_analyzer analyzer, byte **arg_p,
   if (!(this->*analyzer)(arg_p))
     return 0;
   
-  byte *arg_v= *arg_p;
   List_iterator<Item> li(list);
   Item *item;
   while ((item= li++))
@@ -2820,6 +2819,7 @@ Item *Item_cond::compile(Item_analyzer analyzer, byte **arg_p,
       The same parameter value of arg_p must be passed
       to analyze any argument of the condition formula.
     */   
+    byte *arg_v= *arg_p;
     Item *new_item= item->compile(analyzer, &arg_v, transformer, arg_t);
     if (new_item && new_item != item)
       li.replace(new_item);

sql/item_func.cc

@@ -304,7 +304,6 @@ Item *Item_func::compile(Item_analyzer analyzer, byte **arg_p,
 {
   if (!(this->*analyzer)(arg_p))
     return 0;
-  byte *arg_v= *arg_p;
   if (arg_count)
   {
     Item **arg,**arg_end;
@@ -314,6 +313,7 @@ Item *Item_func::compile(Item_analyzer analyzer, byte **arg_p,
         The same parameter value of arg_p must be passed
         to analyze any argument of the condition formula.
       */   
+      byte *arg_v= *arg_p;
       Item *new_item= (*arg)->compile(analyzer, &arg_v, transformer, arg_t);
       if (new_item && *arg != new_item)
         current_thd->change_item_tree(arg, new_item);

sql/sql_select.cc

@@ -6919,9 +6919,9 @@ static COND *build_equal_items_for_cond(COND *cond,
       as soon the field is not of a string type or the field reference is
       an argument of a comparison predicate. 
     */ 
-    byte *dummy;
+    byte *is_subst_valid= (byte *) 1;
     cond= cond->compile(&Item::subst_argument_checker,
-                        &dummy, 
+                        &is_subst_valid, 
                         &Item::equal_fields_propagator,
                         (byte *) inherited);
     cond->update_used_tables();