Description:
------------
Using a prepared statement with positional parameters will produce unexpected behaviour when casting these parameters.



Test script:
---------------
// pdo
$pdo = new \PDO("pgsql:host=localhost;dbname=db", "user", "pwd");
$pdo->setAttribute (\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);


$st = $pdo->prepare('SELECT ?::char as i');
$st->bindValue(1, '1');
$st->execute();
var_dump($st->fetch()); // return false


$st = $pdo->prepare('SELECT (?)::char as i');
$st->bindValue(1, '1');
$st->execute();
var_dump($st->fetch());  // return array(1) { ["i"]=> string(1) "1" }


// old pg extension
$dbconn = pg_connect("host=localhost dbname=superdpi user=postgres  password=df54tb70");
$result = pg_prepare($dbconn, "my_query", 'SELECT $1::char as i');
$result = pg_execute($dbconn, "my_query", array("1"));
var_dump(pg_fetch_assoc ( $result)); // return array(1) { ["i"]=> string(1) "1" }


Expected result:
----------------
array(2) {
  ["i"]=>
  string(1) "1"
  [0]=>
  string(1) "1"
}
array(2) {
  ["i"]=>
  string(1) "1"
  [0]=>
  string(1) "1"
}
array(1) {
  ["i"]=>
  string(1) "1"
}

Actual result:
--------------
bool(false)
array(2) {
  ["i"]=>
  string(1) "1"
  [0]=>
  string(1) "1"
}
array(1) {
  ["i"]=>
  string(1) "1"
}