"Incorrect column name" when "CREATE TABLE t1 AS SELECT spvar"

DROP VIEW IF EXISTS v1;

DROP TABLE IF EXISTS t1,t2;

DROP PROCEDURE IF EXISTS p1;

SET sql_mode=ORACLE;

CREATE TABLE t1 (x INT);

CREATE VIEW v1 AS SELECT x+1 AS a,x+1 AS b FROM t1;

DELIMITER $$

CREATE PROCEDURE p1

AS

  a INT;

  b INT;

BEGIN

  CREATE TABLE t2 AS SELECT a,b FROM v1;

  SHOW CREATE TABLE t2;

  DROP TABLE t2;

END;

$$

DELIMITER ;

CALL p1();

ERROR 1166 (42000): Incorrect column name 'b '