Bugfix for WHERE key=@a OR key=@b

Docs/manual.texi:
  Changelog
sql/sql_select.cc:
  Cleanup

Docs/manual.texi

@@ -46888,6 +46888,11 @@ not yet 100% confident in this code.
 @appendixsubsec Changes in release 3.23.47
 @itemize @bullet
 @item
+Fixed in when using the following construct:
+@code{SELECT ... WHERE key=@@var_name OR $key=@@var_name2}
+@item
+Restrict InnoDB keys to 500 bytes.
+@item
 InnoDB now supports @code{NULL} in keys.
 @item
 Fixed shutdown problem on HPUX. (Introduced in 3.23.46)

mysql-test/r/variables.result

@@ -12,3 +12,14 @@ NULL	NULL	NULL	NULL
 5	5	1	4
 @t5
 1.23456
+@min_cid:=min(c_id)	@max_cid:=max(c_id)
+1	4
+c_id	c_name	c_country
+1	Bozo	USA
+4	Mr. Floppy	GB
+c_id	c_name	c_country
+1	Bozo	USA
+4	Mr. Floppy	GB
+c_id	c_name	c_country
+1	Bozo	USA
+4	Mr. Floppy	GB

mysql-test/t/variables.test

@@ -1,6 +1,7 @@
 #
 # test variables
 #
+drop table if exists t1;
 set @`test`=1,@TEST=3,@select=2,@t5=1.23456;
 select @test,@`select`,@TEST,@not_used;
 set @test_int=10,@test_double=1e-10,@test_string="abcdeghi",@test_string2="abcdefghij",@select=NULL;
@@ -14,3 +15,15 @@ select @test_int,@test_double,@test_string,@test_string2;
 select @t1:=(@t2:=1)+@t3:=4,@t1,@t2,@t3;
 select @t5;
 
+#
+# Test problem with WHERE and variables
+#
+
+CREATE TABLE t1 (c_id INT(4) NOT NULL, c_name CHAR(20), c_country CHAR(3), PRIMARY KEY(c_id));
+INSERT INTO t1 VALUES (1,'Bozo','USA'),(2,'Ronald','USA'),(3,'Kinko','IRE'),(4,'Mr. Floppy','GB');
+SELECT @min_cid:=min(c_id), @max_cid:=max(c_id) from t1;
+SELECT * FROM t1 WHERE c_id=@min_cid OR c_id=@max_cid;
+SELECT * FROM t1 WHERE c_id=@min_cid OR c_id=@max_cid OR c_id=666;
+ALTER TABLE t1 DROP PRIMARY KEY;
+select * from t1 where c_id=@min_cid OR c_id=@max_cid;
+drop table t1;

sql/item_func.cc

@@ -1772,6 +1772,16 @@ Item_func_set_user_var::val_str(String *str)
 }
 
 
+void Item_func_set_user_var::print(String *str)
+{
+  str->append('(');
+  str->append(name.str,name.length);
+  str->append(":=",2);
+  args[0]->print(str);
+  str->append(')');
+}
+
+
 user_var_entry *Item_func_get_user_var::get_entry()
 {
   if (!entry  || ! entry->value)
@@ -1864,6 +1874,34 @@ enum Item_result Item_func_get_user_var::result_type() const
   return entry->type;
 }
 
+
+void Item_func_get_user_var::print(String *str)
+{
+  str->append('@');
+  str->append(name.str,name.length);
+  str->append(')');
+}
+
+bool Item_func_get_user_var::eq(const Item *item) const
+{
+  /* Assume we don't have rtti */
+  if (this == item)
+    return 1;					// Same item is same.
+  /* Check if other type is also a get_user_var() object */
+#ifdef FIX_THIS
+  if (item->eq == &Item_func_get_user_var::eq)
+    return 0;
+#else
+  if (item->type() != FUNC_ITEM ||
+      ((Item_func*) item)->func_name() != func_name())
+    return 0;
+#endif
+  Item_func_get_user_var *other=(Item_func_get_user_var*) item;
+  return (name.length == other->name.length &&
+	  !memcmp(name.str, other->name.str, name.length));
+}
+
+
 longlong Item_func_inet_aton::val_int()
 {
   uint byte_result = 0;

sql/item_func.h

@@ -817,6 +817,7 @@ public:
   enum Item_result result_type () const { return cached_result_type; }
   bool fix_fields(THD *thd,struct st_table_list *tables);
   void fix_length_and_dec();
+  void print(String *str);
   const char *func_name() const { return "set_user_var"; }
 };
 
@@ -835,13 +836,16 @@ public:
   longlong val_int();
   String *val_str(String* str);
   void fix_length_and_dec();
+  void print(String *str);
   enum Item_result result_type() const;
   const char *func_name() const { return "get_user_var"; }
   bool const_item() const { return const_var_flag; }
   table_map used_tables() const
   { return const_var_flag ? 0 : RAND_TABLE_BIT; }
+  bool eq(const Item *item) const;
 };
 
+
 class Item_func_inet_aton : public Item_int_func
 {
 public:

sql/sql_select.cc

@@ -35,7 +35,7 @@ const char *join_type_str[]={ "UNKNOWN","system","const","eq_ref","ref",
 			      "MAYBE_REF","ALL","range","index","fulltext" };
 
 static bool make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
-                        DYNAMIC_ARRAY *keyuse);
+				 DYNAMIC_ARRAY *keyuse);
 static bool update_ref_and_keys(THD *thd, DYNAMIC_ARRAY *keyuse,
 				JOIN_TAB *join_tab,
                                 uint tables,COND *conds,table_map table_map);