After some research I found the answer. You can use the static method: cases().

enum Status
{
    case PAID;
    case Cancelled;
}

Status::cases();

The cases method will return an array with an enum (UnitEnum interface) for each value.

In addition to UnitEnum::cases() you can use ReflectionEnum with this

$reflection = new ReflectionEnum(Status::class);

$reflection->getCases();

note that in both cases you will not be able to get the enum methods. but as long as the ReflectionEnum is extending the ReflectionClass so you can use the rest of ReflectionClass methods such as getMethods

Need the values and not Enum instances?

I've written a Composer package for this, othyn/php-enum-enhancements, as the UnitEnum::cases() method wasn't what I was looking for, as that returns an array of MySuperCoolEnum instances instead of the underlying values as their raw type, which is what I wanted.

Its a trait that can be easily added to any enum that does the following:

• Adds a new static UnitEnum::valueArray(): array method that returns all values within an Enum as an equally typed array of Enum values

• Adds a new static UnitEnum::valueList(string $separator = ', '): string method that returns all values within an Enum as a comma separated list string

In which produces the following for normal Enum's:

<?php

namespace App\Enums;

use Othyn\PhpEnumEnhancements\Traits\EnumEnhancements;

enum TestEnum
{
    use EnumEnhancements;

    case Alpha;
    case Bravo;
    case Charlie;
    case Delta;
    case Echo;
}

var_dump(TestEnum::valueArray());

// Results in the following being printed:
// array(5) {
//   [0]=>
//   string(5) "Alpha"
//   [1]=>
//   string(5) "Bravo"
//   [2]=>
//   string(7) "Charlie"
//   [3]=>
//   string(5) "Delta"
//   [4]=>
//   string(4) "Echo"
// }

var_dump(TestEnum::valueList());

// Results in the following being printed:
// string(34) "Alpha, Bravo, Charlie, Delta, Echo"

var_dump(TestEnum::valueList(separator: ':'));

// Results in the following being printed:
// string(30) "Alpha:Bravo:Charlie:Delta:Echo"

... and the following for Backed Enum's, the following being a string example:

<?php

namespace App\Enums;

use Othyn\PhpEnumEnhancements\Traits\EnumEnhancements;

enum TestStringBackedEnum: string
{
    use EnumEnhancements;

    case Alpha   = 'alpha';
    case Bravo   = 'bravo';
    case Charlie = 'charlie';
    case Delta   = 'delta';
    case Echo    = 'echo';
}

var_dump(TestStringBackedEnum::valueArray());

// Results in the following being printed:
// array(5) {
//   [0]=>
//   string(5) "alpha"
//   [1]=>
//   string(5) "bravo"
//   [2]=>
//   string(7) "charlie"
//   [3]=>
//   string(5) "delta"
//   [4]=>
//   string(4) "echo"
// }

var_dump(TestStringBackedEnum::valueList());

// Results in the following being printed:
// string(34) "alpha, bravo, charlie, delta, echo"

var_dump(TestStringBackedEnum::valueList(separator: ':'));

// Results in the following being printed:
// string(30) "alpha:bravo:charlie:delta:echo"

... and yes it works on int's too!

There are more examples in the Usage part of the package's README.