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Bug #80391 Iterable not covariant to mixed
Submitted: 2020-11-20 19:34 UTC Modified: 2020-11-24 09:02 UTC
Votes:5
Avg. Score:4.8 ± 0.4
Reproduced:5 of 5 (100.0%)
Same Version:5 (100.0%)
Same OS:3 (60.0%)
From: peldax at gmail dot com Assigned: nikic (profile)
Status: Closed Package: *General Issues
PHP Version: 8.0.0RC5 OS: All
Private report: No CVE-ID: None
 [2020-11-20 19:34 UTC] peldax at gmail dot com
Description:
------------
Hello,

When I declare a function in a class/interface with "mixed" return type, and than extend the class and apply covariant return type "iterable", I get compatibility error saying that functions are not compatible.

Code snippet bellow gives me:

Fatal error: Declaration of Child::getValue(): iterable must be compatible with SomeInterface::getValue(): mixed

I am not sure if "iterable" has any special treatment (it works correctly for other types, such as int, self, Child, ...) or is it just forgotten pseudo type.

Thank you.

Václav Pelíšek @peldax

Test script:
---------------
<?php

interface SomeInterface {
    public function getValue() : mixed;
}

class Child implements SomeInterface
{
    public function getValue() : iterable
    {
        return [];
    }
}

Expected result:
----------------
Script compiles successfully.

Actual result:
--------------
Fatal error: Declaration of Child::getValue(): iterable must be compatible with SomeInterface::getValue(): mixed

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History

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 [2020-11-20 19:56 UTC] peldax at gmail dot com
Strange addition:

Contravariace works correctly, following script compiles succesfully:

<?php

interface SomeInterface {
    public function getValue(iterable $arg) : void;
}


class Child implements SomeInterface
{
    public function getValue(mixed $arg) : void
    {
        return;
    }
}
 [2020-11-24 09:02 UTC] nikic@php.net
-Assigned To: +Assigned To: nikic
 [2020-11-24 09:10 UTC] nikic@php.net
Automatic comment on behalf of nikita.ppv@gmail.com
Revision: http://git.php.net/?p=php-src.git;a=commit;h=912cb8b8b52f958ac6eb482466c01e99fc0c0e35
Log: Fixed bug #80391
 [2020-11-24 09:10 UTC] nikic@php.net
-Status: Assigned +Status: Closed
 
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