PDO with pgsql changed data types returned from float queries starting with PHP 8.4

[janedbal]

Description

The following code:

<?php

$pdo = new PDO('pgsql:host=pgsql;dbname=foo', 'root', 'secret');
$pdo->exec('DROP TABLE IF EXISTS test');
$pdo->exec('CREATE TABLE test (col_float FLOAT)');
$pdo->exec('INSERT INTO test VALUES (0.125)');

$result = $pdo->query('SELECT col_float FROM test')->fetchColumn();

var_dump($result);

Resulted in this output:

float(0.125)

But I expected this output instead:

string(5) "0.125"

---

This behaviour changes in PHP 8.4 (prior this version, you always get string) and seems to affect all float results. This was detected by failing phpstan-doctrine tests where we infer data types returned from drivers.

I didnt find any relevant note about this behaviour change in UPGRADING notes, so this feels unintentional. I suspect #14035 might be the cause.

I can provide fully dockerized repository for reproduction if needed.

PHP Version

PHP 8.4.0beta4

Operating System

Debian 12 (bookworm)

[janedbal]

Just after submission, I found this commit. So maybe it is intentional and just lacks proper documentation in release notes? Seems significant change to me.

[cmb69]

Yeah, there needs to be a note in UPGRADING, since this is a BC break, in my opinion.