[5.8] Binding value as PDO::PARAM_INT has different behaviour in PHP 7.2 + MysqlConnection

[frederikbosch]

When binding a value against a MySQL PDO statement, the behaviour between PHP 7.1 and PHP 7.2 differs. When you bind a value as integer while passing a float, this was no problem with PHP7.1. However, it became a problem in PHP7.2.

The problem is when executing the following. It inserts 0.5 in PHP7.1, and 0 in PHP7.2. I have tested this against MariaDB (10.1 and 10.2), not against MySQL. Another person also found difference in behaviour: https://stackoverflow.com/questions/54413798/pdoparam-int-behaviour-in-php-7-1-php-7-2.

$stmt = $pdo->prepare('INSERT INTO tbl (val) VALUES (?)');
$stmt->bindValue(1, 0.5, PDO::PARAM_INT);

This PR fixes that issue. Moreover, it includes tests for the possible PDO::PARAM_XXX used my the bindValue method in MysqlConnection.

Because I am wondering if this is intended behaviour of PHP, I also opened a PHP bug report for it. Nonetheless, I think that using PDO::PARAM_STR is better for floating points than using PDO::PARAM_INT.

[frederikbosch]

If someone wants to test this (e.g. on a MySQL instead of MariaDB server), you can use the following script.

[frederikbosch]

Hmm, I just found out that this caused a pain already and has been discussed multiple times. I have learned so far that PDO::PARAM_INT is used because of JSON comparison (#16069 and #16063) and that other people already submitted issues for the same problem I have #23850, #27596, #26817 and #25818.

[frederikbosch]

The commit in the PHP source that is causing is the following one and this is the related bug report.

[taylorotwell]

Don't think we can do this for reasons noted in other issues. I assume you are using EMULATE_PREPARES?