PHP Notice: Use of undefined constant MCRYPT_RIJNDAEL_128 - assumed

错误原因是没有安装php的mcrypt扩展。

解决办法：安装mcrypt扩展

安装laravel 5.2的时候，命令运行如下代码：

$ composer install
Loading composer repositories with package information
Updating dependencies (including require-dev)
  - Installing paragonie/random_compat (v1.4.1)
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  - Installing doctrine/inflector (v1.1.0)
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  - Installing danielstjules/stringy (1.10.0)
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  - Installing illuminate/contracts (v5.1.41)
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  - Installing illuminate/support (v5.1.41)
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  - Installing symfony/polyfill-mbstring (v1.3.0)
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  - Installing symfony/translation (v2.7.21)
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  - Installing nesbot/carbon (1.21.0)
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  - Installing symfony/http-foundation (v2.7.21)
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  - Installing symfony/finder (v2.7.21)
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  - Installing illuminate/session (v5.1.41)
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  - Installing psr/log (1.0.2)
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  - Installing symfony/event-dispatcher (v2.8.14)
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  - Installing symfony/debug (v2.7.21)
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  - Installing symfony/http-kernel (v2.7.21)
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  - Installing illuminate/http (v5.1.41)
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  - Installing illuminate/html (v5.0.0)
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  - Installing edvinaskrucas/notification (dev-features/laravel-5 b3172df)
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  - Installing caouecs/laravel-lang (3.0.19)
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  - Installing overtrue/laravel-lang (dev-master 4ff1b61)
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  - Installing yuanchao/laravel-5-markdown-editor (dev-master 420f936)
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  - Installing laracasts/generators (dev-master 3d8ae83)
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  - Installing vlucas/phpdotenv (v1.1.1)
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  - Installing symfony/var-dumper (v2.7.21)
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  - Installing symfony/routing (v2.7.21)
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  - Installing symfony/process (v2.7.21)
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  - Installing symfony/dom-crawler (v2.7.21)
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  - Installing symfony/css-selector (v2.8.14)
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  - Installing symfony/console (v2.7.21)
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  - Installing swiftmailer/swiftmailer (v5.4.4)
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  - Installing jakub-onderka/php-console-color (0.1)
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  - Installing jakub-onderka/php-console-highlighter (v0.3.2)
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  - Installing dnoegel/php-xdg-base-dir (0.1)
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  - Installing nikic/php-parser (v2.1.1)
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  - Installing psy/psysh (v0.7.2)
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  - Installing mtdowling/cron-expression (v1.1.0)
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  - Installing monolog/monolog (1.22.0)
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  - Installing league/flysystem (1.0.32)
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  - Installing symfony/polyfill-util (v1.3.0)
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  - Installing symfony/polyfill-php56 (v1.3.0)
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  - Installing jeremeamia/superclosure (2.3.0)
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  - Installing classpreloader/classpreloader (3.1.0)
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  - Installing laravel/framework (v5.1.45)
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  - Installing psr/http-message (1.0.1)
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  - Installing illuminate/hashing (v5.1.41)
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  - Installing illuminate/filesystem (v5.1.41)
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  - Installing illuminate/config (v5.1.41)
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  - Installing sebastian/diff (1.4.1)
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  - Installing sebastian/comparator (1.2.2)
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paragonie/random_compat suggests installing ext-libsodium (Provides a modern crypto API that can be used to generate random bytes.)
symfony/translation suggests installing symfony/config ()
symfony/event-dispatcher suggests installing symfony/dependency-injection ()
symfony/http-kernel suggests installing symfony/browser-kit ()
symfony/http-kernel suggests installing symfony/class-loader ()
symfony/http-kernel suggests installing symfony/config ()
symfony/http-kernel suggests installing symfony/dependency-injection ()
symfony/var-dumper suggests installing ext-symfony_debug ()
symfony/routing suggests installing symfony/config (For using the all-in-one router or any loader)
symfony/routing suggests installing symfony/expression-language (For using expression matching)
psy/psysh suggests installing ext-pdo-sqlite (The doc command requires SQLite to work.)
monolog/monolog suggests installing aws/aws-sdk-php (Allow sending log messages to AWS services like DynamoDB)
monolog/monolog suggests installing doctrine/couchdb (Allow sending log messages to a CouchDB server)
monolog/monolog suggests installing ext-amqp (Allow sending log messages to an AMQP server (1.0+ required))
monolog/monolog suggests installing ext-mongo (Allow sending log messages to a MongoDB server)
monolog/monolog suggests installing graylog2/gelf-php (Allow sending log messages to a GrayLog2 server)
monolog/monolog suggests installing mongodb/mongodb (Allow sending log messages to a MongoDB server via PHP Driver)
monolog/monolog suggests installing php-amqplib/php-amqplib (Allow sending log messages to an AMQP server using php-amqplib)
monolog/monolog suggests installing php-console/php-console (Allow sending log messages to Google Chrome)
monolog/monolog suggests installing rollbar/rollbar (Allow sending log messages to Rollbar)
monolog/monolog suggests installing ruflin/elastica (Allow sending log messages to an Elastic Search server)
monolog/monolog suggests installing sentry/sentry (Allow sending log messages to a Sentry server)
league/flysystem suggests installing league/flysystem-aws-s3-v2 (Allows you to use S3 storage with AWS SDK v2)
league/flysystem suggests installing league/flysystem-aws-s3-v3 (Allows you to use S3 storage with AWS SDK v3)
league/flysystem suggests installing league/flysystem-azure (Allows you to use Windows Azure Blob storage)
league/flysystem suggests installing league/flysystem-cached-adapter (Flysystem adapter decorator for metadata caching)
league/flysystem suggests installing league/flysystem-copy (Allows you to use Copy.com storage)
league/flysystem suggests installing league/flysystem-dropbox (Allows you to use Dropbox storage)
league/flysystem suggests installing league/flysystem-eventable-filesystem (Allows you to use EventableFilesystem)
league/flysystem suggests installing league/flysystem-rackspace (Allows you to use Rackspace Cloud Files)
league/flysystem suggests installing league/flysystem-sftp (Allows you to use SFTP server storage via phpseclib)
league/flysystem suggests installing league/flysystem-webdav (Allows you to use WebDAV storage)
league/flysystem suggests installing league/flysystem-ziparchive (Allows you to use ZipArchive adapter)
laravel/framework suggests installing aws/aws-sdk-php (Required to use the SQS queue driver and SES mail driver (~3.0).)
laravel/framework suggests installing fzaninotto/faker (Required to use the eloquent factory builder (~1.4).)
laravel/framework suggests installing guzzlehttp/guzzle (Required to use the Mailgun and Mandrill mail drivers and the ping methods on schedules (~5.3|~6.0).)
laravel/framework suggests installing iron-io/iron_mq (Required to use the iron queue driver (~2.0).)
laravel/framework suggests installing league/flysystem-aws-s3-v3 (Required to use the Flysystem S3 driver (~1.0).)
laravel/framework suggests installing league/flysystem-rackspace (Required to use the Flysystem Rackspace driver (~1.0).)
laravel/framework suggests installing pda/pheanstalk (Required to use the beanstalk queue driver (~3.0).)
laravel/framework suggests installing pusher/pusher-php-server (Required to use the Pusher broadcast driver (~2.0).)
laravel/framework suggests installing symfony/psr-http-message-bridge (Required to psr7 bridging features (0.2.*).)
intervention/image suggests installing ext-imagick (to use Imagick based image processing.)
intervention/image suggests installing intervention/imagecache (Caching extension for the Intervention Image library)
illuminate/filesystem suggests installing league/flysystem-aws-s3-v3 (Required to use the Flysystem S3 driver (~1.0).)
illuminate/filesystem suggests installing league/flysystem-rackspace (Required to use the Flysystem Rackspace driver (~1.0).)
predis/predis suggests installing ext-phpiredis (Allows faster serialization and deserialization of the Redis protocol)
sebastian/global-state suggests installing ext-uopz (*)
phpunit/php-code-coverage suggests installing ext-xdebug (>=2.2.1)
phpunit/phpunit suggests installing phpunit/php-invoker (~1.1)
phpspec/phpspec suggests installing phpspec/nyan-formatters (~1.0 – Adds Nyan formatters)
Package illuminate/html is abandoned, you should avoid using it. Use laravelcollective/html instead.
Writing lock file
Generating autoload files
> php artisan clear-compiled
PHP Notice:  Use of undefined constant MCRYPT_RIJNDAEL_128 - assumed 'MCRYPT_RIJNDAEL_128' in /Users/zhouyulong/web/laravel-5-blog/config/app.php on line 83

Notice: Use of undefined constant MCRYPT_RIJNDAEL_128 - assumed 'MCRYPT_RIJNDAEL_128' in /Users/zhouyulong/web/laravel-5-blog/config/app.php on line 83
> php artisan optimize
PHP Notice:  Use of undefined constant MCRYPT_RIJNDAEL_128 - assumed 'MCRYPT_RIJNDAEL_128' in /Users/zhouyulong/web/laravel-5-blog/config/app.php on line 83

Notice: Use of undefined constant MCRYPT_RIJNDAEL_128 - assumed 'MCRYPT_RIJNDAEL_128' in /Users/zhouyulong/web/laravel-5-blog/config/app.php on line 83
Generating optimized class loader

竟然有报错信息，真的好晕了，怎么办？

mcrypt是php里面重要的加密支持扩展库,需要安装这个吧！

需要安装mcrypt

$ brew install mcrypt

$ brew install php56-mcrypt
==> Installing php56-mcrypt from homebrew/php
Error: You must `brew link jpeg unixodbc` before homebrew/php/php56-mcrypt can be installed

有报错了，安装php56-mcrypt之前要命令运行如下：

$ brew link jpeg unixodbc
Linking /usr/local/Cellar/jpeg/8d... 0 symlinks created
Linking /usr/local/Cellar/unixodbc/2.3.4... 0 symlinks created

好了，直接可以命令运行：

$ brew install php56-mcrypt