Description:
------------
The issue is reproducible in the following environment:

1. PHP 7.1(.5), IBM DB2 10.5. Not reproducible on PHP 5.6.30 and PHP 7.0.19 in the exact same environment.
2. A boolean value is bound to an integer column (e.g. a SMALLINT).
3. The boolean value is not a literal but a result of comparison of an array element to a string literal (just comparing strings will not work, see example).
4. The query in question is not the first query executed after connecting to the DB.


Test script:
---------------
/*
CREATE TABLE DB2_TEST
(
    ID smallint DEFAULT 0
)
*/

$dsn = 'HOSTNAME=localhost;UID=db2inst1;PWD=Passw0rd;DATABASE=test';
$conn = db2_connect($dsn, null, null);

if (!$conn) {
    echo db2_conn_errormsg(), PHP_EOL;
    exit(1);
}

printf('PHP: %s' . PHP_EOL, phpversion());
printf('ibm_db2: %s' . PHP_EOL, phpversion('ibm_db2'));
$server = db2_server_info($conn);
printf('DB2 NAME: %s, VERSION: %s' . PHP_EOL, $server->DBMS_NAME, $server->DBMS_VER);

// without executing a query before the following one, the issue is not reproducible
$stmt = db2_prepare($conn, 'SELECT 1 FROM SYSIBM.SYSDUMMY1');
$result = db2_execute($stmt);

if (!$result) {
    echo db2_stmt_errormsg(), PHP_EOL;
    exit(1);
}

// the value of $true is the result of comparison of an array element value
// with the same value. if it's just literal true, the issue is not reproducible
$array = array('key' => 'value');
$true = $array['key'] == 'value';

$stmt = db2_prepare($conn, 'SELECT ID FROM DB2_TEST WHERE ID = ?');
$result = db2_execute($stmt, [$true]);

if (!$result) {
    echo db2_stmt_errormsg(), PHP_EOL;
    exit(1);
}

echo 'OK', PHP_EOL;


Expected result:
----------------
The second call to db2_execute() is expected to return TRUE. OK is displayed.

Actual result:
--------------
[IBM][CLI Driver] CLI0111E  Numeric value out of range. SQLSTATE=22003 SQLCODE=-99999