MessageFormatter throws error on unused datetime value

[naturefund-falk]

Description

The following code:

<?php
$fmt = new MessageFormatter('de', 'Beispiel ohne Benutzung');

echo $fmt->format(['payed' => new DateTimeImmutable()]);

Resulted in this output:

PHP Fatal error:  Uncaught Error: Object of class DateTimeImmutable could not be converted to string in /home/development/fst/src/tests/messageFormatter.php:5

But I expected this output instead:

No error, because value not used. No reason to convert the datetime value to a string

Intl data

Internationalization support => enabled
ICU version => 72.1
ICU Data version => 72.1
ICU TZData version => 2022e
ICU Unicode version => 15.0

PHP Version

PHP 8.2.24

Operating System

Debian 12

[devnexen]

I ll have a look into this, your report makes sense tough.

[nielsdos]

I'm closing this as "not a bug" as according to the conversation in #16816.

[naturefund-falk]

The Problem may be on another level. Because the value isnt used, the helper function (from the mentioned conversation) does not know that the value is a date value (and could be converted to a string as a date).
If i use the value in the message as '{ payed, date }', it all works fine.
The reason for the (possible) missing parameter is that the message itself comes from a translation source and the translator may drop this parameter from the message in his translation. At the end i have a translation which work in some languages and in some not.
Maybe the question in the messageformatter_helper.cpp is, why it does not know that the value is a date, i mean it as a DateTimeImmutable object.

[nielsdos]

I think I understand your concern. I'm not entirely sure it's possible to handle this in a consistent way in the extension interface to the C library though...