Will grouped Laravel routes be cached? Where are they cached?

Question

As stated in the docs

Closure based routes cannot be cached. To use route caching, you must convert any Closure routes to controller classes.

But if I want to group routes I can make the route itself point to a controller (function) but the group will still be a Closure

Route::group(array('prefix' => 'admin', 'before' => 'auth'), function() // Closure
{
    Route::get('/', 'Examplecontroller@bla'); // non Closure
});

Maybe for research purposes: Where are the routes cached?

Answer 1

Will grouped Laravel routes be cached? Where are they cached?

Yes, if body of the group is also another group or non-closure like route.

They are stored in bootstrap/cache folder.

---

Behind the scenes

Closure like group (non cacheable):

Route::group(['middleware' => ['guest'], function() {
    Route::get('/hi', function() {
        dd('Hi I am closure');
    });
});

Non-closure like group

Route::group(['middleware' => ['guest'], function() {
    Route::get('/hi', 'WelcomeController@hi');
    Route::get('/bye', 'WelcomeController@bye');
});

In fact second example is a closure (obviously) but (my guess is) Laravel will detect the closure contains only another routes (that are "cacheable") and rewrite it behind the scenes to following (this is not precisely correct and Laravel does not rewrite anything its simple demonstration how it might look, in reality Laravel uses Illuminate\Routing\RouteCollection object):

Route::get('/hi', 'WelcomeController@hi')->middleware('guest');
Route::get('/bye', 'WelcomeController@bye')->middleware('guest');

And cache it.

My assumption is that Laravel does some kind of foreach + try/catch and if the body of group throws ErrorException (serialisation error) it simply aborts itself and shouts at coder that its not possible.

---

Code for $artisan route:cache is here

And this is the code that determines if route is or is not "cacheable" from route.php

public function prepareForSerialization()
{
    if ($this->action['uses'] instanceof Closure) {
        throw new LogicException("Unable to prepare route [{$this->uri}] for serialization. Uses Closure.");
    }

    $this->compileRoute();

    unset($this->router, $this->container);
}