[5.4] Move "tap" method to BuildsQueries trait.

[ed-fruty]

Method tap was moved from Illuminate\Database\Query\Builder to Illuminate\Database\Concerns\BuildsQueries trait.

Eloquent builder when and tap methods passes different builder instances to the callback.
when passes current eloquent builder to the callback, but tap method uses Illuminate\Database\Query\Builder as callback argument.

For example:

>>> (new User)->newQuery()->tap(function($builder) { dd(get_class($builder)); });
"Illuminate\Database\Query\Builder"

>>> (new User)->newQuery()->when(true, function($builder) { dd(get_class($builder)); });
"Illuminate\Database\Eloquent\Builder"

So, we can't use one type hint callback for when/tap methods, like (class callback case will illustrate this better):

class SomeBuilderCallback
{
   public function __invoke(Illuminate\Database\Eloquent\Builder $builder)
   {
       // do stuff
   }
}

// In one part of application
User::when($condition, new SomeBuilderCallback);

// In other part
User::tap(new SomeBuilderCallback); // will fail

[taylorotwell]

I don't understand what bug this is fixing.

[ed-fruty]

@taylorotwell , so is it normal behavior when i get different builder instances in the similar methods ?

$query->when(true, function ($builder) {

   // Instance of Illuminate\Database\Eloquent\Builder

})->tap(function ($builder) {

  // Another builder instance. Illuminate\Database\Query\Builder

});

Why not one builder instance in the above methods?

[ed-fruty]

@taylorotwell , in addition, with tap method i can't use eloquent builder features, like

Model::tap(function ($builder) {
   /*
    * This will throw an exception
    * BadMethodCallException with message 'Call to undefined method Illuminate\Database\Query\Builder::with()'
    */
   $builer->with('relation');

});