Array cast should emit an error

[mvorisek]

Feature Request

Array cast is redundant on array type. (redundant cast emit a phpstan error already)

For scalar type values it wraps the value into an array - inconsistent with casting an array, array is not wrapped again.

For null it produces empty array - can be a mistake in code, scalar type value is wrapped in an array and never empty.

For objects - get_object_vars should be used.

Given these reasons, I would expect phpstan to emit an error if an (array) cast is found.

demo: https://3v4l.org/2INk8

playground: https://phpstan.org/r/e03daaef-49f6-4c30-b029-24bed8f50048 (line 10 should emit an error)

[VincentLanglet]

For scalar type values it wraps the value into an array - inconsistent with casting an array, array is not wrapped again.

I often see the following method

/**
 * @param string|string[] $messages
 */
public function doThings($messages)
{
    $messages = (array) $messages;
    foreach ($messages as $message) {
        // ...
    }
}

Writing

$messages = (array) $messages;

is shorter than

if (!is_array($messages) {
     $messages = [$messages];
}

and casting to an array is exactly what we want to do, since we don't want to wrap again an existing array.

So I do not consider an (array) cast as an error, even in strict rules.

[mvorisek]

that is true, but if an object is passed, the array cast is almost always wrong, so the variant with if should be preffered

also null is typically not wanted to be casted, again, the variant with if should be preffered

[VincentLanglet]

The phpdoc is asking for string or string[]. If you are passing null or an object you already have an error from phpstan-core. You also can use string|array as a native param typehint if you use php 8.

[mvorisek]

as long as the input is restricted by hard type and not-null/non-array-accepting phpdoc type

https://phpstan.org/r/d9d9c0ce-e0b6-4e4c-9ebd-92636312f21c

in both cases, I would expect a phpstan error with this feature request