Warningが出る場合、Laravel IDE Helperをインストールしよう

composer require --dev barryvdh/laravel-ide-helper

config/app.php

    'providers' => [
        /*
         * Package Service Providers...
         */
        Barryvdh\LaravelIdeHelper\IdeHelperServiceProvider::class,

app/Providers/AppServiceProvider.php

    public function register()
    {
        if ($this->app->isLocal()) {
            $this->app->register(\Barryvdh\LaravelIdeHelper\IdeHelperServiceProvider::class);
        }
    }

php artisan ide-helper:generate

_ide_helper.php をダウンロードだけでも大丈夫です
https://gist.github.com/barryvdh/5227822

Undefined class 'App'

Undefined class 'Arr'

Undefined class 'Artisan'

Undefined class 'Auth'

Undefined class 'Blade'

Undefined class 'Broadcast'

Undefined class 'Bus'

Undefined class 'Cache'

Undefined class 'Config'

Undefined class 'Cookie'

Undefined class 'Crypt'

Undefined class 'Date'

Undefined class 'DB'

Undefined class 'Eloquent'

Undefined class 'Event'

Undefined class 'File'

Undefined class 'Gate'

Undefined class 'Hash'

Undefined class 'Http'

Undefined class 'Js'

Undefined class 'Lang'

Undefined class 'Log'

Undefined class 'Mail'

Undefined class 'Notification'

Undefined class 'Password'

Undefined class 'Queue'

Undefined class 'RateLimiter'

Undefined class 'Redirect'

Undefined class 'Request'

Undefined class 'Response'

Undefined class 'Route'

Undefined class 'Schema'

Undefined class 'Session'

Undefined class 'Storage'

Undefined class 'Str'

Undefined class 'URL'

Undefined class 'Validator'

Undefined class 'View'

Undefined class 'Vite'

参考