Misleading error message for array unpacking of objects/enums in constant expression

[TysonAndre]

Description

The following code:

<?php
const EXAMPLE = [...new ArrayObject()];

Resulted in this output:

Warning: Uncaught Error: Only arrays and Traversables can be unpacked in ...

But I expected this output (something along these lines) instead:

Warning: Uncaught Error: Cannot unpack Traversables in constant expression in ...

This should be improved in php 8.3

PHP Version

8.1+

Operating System

No response

[cmb69]

Indeed, this error message is wrong. Given that there still will be two RCs for 8.2, it might make sense to fix it right away.

[jhdxr]

Indeed. For constant expression actually only arrays are accepted. This issue is shadowed coz new is not allowed before.

[jhdxr]

@cmb69 , I created a PR targeting 8.1 as this is indeed a bug and 8.1 is still in support. However if you believe this is a BC break that doesn't suitable for 8.1, feel free to change the target branch to 8.2.

[cmb69]

I'm unsure about which branch to target. There is a recent discussion on internals about unserialization where the point was made by some that changing an exception message would constitute a BC break, even for an Error exception.

[derickr]

That's a silly thing. Message texts are not, and have never been considered stable.

[jhdxr]

That's a silly thing. Message texts are not, and have never been considered stable.

Personally I fully agree with you, but I did see the debatees on mail list as well. Anyway, I leave the PR open for RMs to decide which branch is suitable.

[cmb69]

Anyway, I leave the PR open for RMs to decide which branch is suitable.

Then we should ask the RMs: @ramsey, @patrickallaert, @krakjoe, what do you think?

[ramsey]

I'm okay with changing the error message.