Framework: EloquentCollection->intersect misbehaves when called with null argument

[jonaslm]

• Laravel Version: 6.5.1
• PHP Version: 7.3
• Database Driver & Version: N/A

Description:

When calling $collection->intersect(null) on an Eloquent Collection the whole $collection is returned. I would expect an error or, possibly, an empty collection to be returned. Note that doing the same thing on a regular base collection returns an empty collection.

We had this happen, causing silent errors (we called intersect with a nonexistant relation as argument, which gets returned as null).

Steps To Reproduce:

Assuming you have an Eloquent Collection $eloquentCollection that isn't empty, simply call

$eloquentCollection->intersect(null);

The entire collection will be returned. Expected behavior would be an error or, possibly, an empty collection. Again, note that doing the same thing on a base collection returns an empty collection.

[driesvints]

Tested this and confirmed. This indeed seems like unwanted behavior. Welcoming prs for this.

[ahinkle]

Hmm, am I missing something here? $collection->intersect(null) returns an empty collection.

https://github.com/laravel/framework/blob/1bbe5528568555d597582fdbec73e31f8a818dbc/tests/Support/SupportCollectionTest.php#L1151-L1158

https://github.com/laravel/framework/blob/1bbe5528568555d597582fdbec73e31f8a818dbc/tests/Support/SupportCollectionTest.php#L1160-L1167

[if4lcon]

@ahinkle this bug only occurs on Eloquent collection