我在这里的其他帖子上看到过这个问题的答案，但没有一个答案对我有用。主要是因为我试图在我的mac上本地安装laravel，而答案是针对Linux环境的，brew声称它没有这个扩展名。下面是我运行composer命令时的输出：

$ composer global require "laravel/installer"

Changed current directory to /Users/frankaddelia/.composer
Using version ^2.0 for laravel/installer
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - laravel/installer v2.0.1 requires ext-zip * -> the requested PHP extension zip is missing from your system.
    - laravel/installer v2.0.0 requires ext-zip * -> the requested PHP extension zip is missing from your system.
    - Installation request for laravel/installer ^2.0 -> satisfiable by laravel/installer[v2.0.0, v2.0.1].

  To enable extensions, verify that they are enabled in your .ini files:
    - /usr/local/php5/lib/php.ini
    - /usr/local/php5/php.d/10-extension_dir.ini
    - /usr/local/php5/php.d/20-extension-opcache.ini
    - /usr/local/php5/php.d/40-curl.ini
    - /usr/local/php5/php.d/40-openssl.ini
    - /usr/local/php5/php.d/50-extension-apcu.ini
    - /usr/local/php5/php.d/50-extension-curl.ini
    - /usr/local/php5/php.d/50-extension-gmp.ini
    - /usr/local/php5/php.d/50-extension-igbinary.ini
    - /usr/local/php5/php.d/50-extension-imap.ini
    - /usr/local/php5/php.d/50-extension-intl.ini
    - /usr/local/php5/php.d/50-extension-mcrypt.ini
    - /usr/local/php5/php.d/50-extension-mongodb.ini
    - /usr/local/php5/php.d/50-extension-mssql.ini
    - /usr/local/php5/php.d/50-extension-pdo_pgsql.ini
    - /usr/local/php5/php.d/50-extension-pgsql.ini
    - /usr/local/php5/php.d/50-extension-propro.ini
    - /usr/local/php5/php.d/50-extension-raphf.ini
    - /usr/local/php5/php.d/50-extension-readline.ini
    - /usr/local/php5/php.d/50-extension-redis.ini
    - /usr/local/php5/php.d/50-extension-xsl.ini
    - /usr/local/php5/php.d/99-liip-developer.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.

Installation failed, reverting ./composer.json to its original content.

我尝试用brew安装缺少的扩展，但我得到这样的错误：

$ brew install php7.2-zip
Updating Homebrew...
Error: No available formula with the name "php7.2-zip" 
==> Searching for a previously deleted formula (in the last month)...
Warning: homebrew/core is shallow clone. To get complete history run:
  git -C "$(brew --repo homebrew/core)" fetch --unshallow

Error: No previously deleted formula found.
==> Searching for similarly named formulae...
Error: No similarly named formulae found.
==> Searching taps...
==> Searching taps on GitHub...
Error: No formulae found in taps.

顺便说一下，这里是我的php版本：

php -v
PHP 7.3.0beta2 (cli) (built: Aug 21 2018 08:13:27) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.3.0-dev, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.3.0beta2, Copyright (c) 1999-2018, by Zend Technologies

我似乎不知道如何得到这个失踪的扩展，并没有找到一个解决方案，为我工作后，几个小时的谷歌搜索。我只是重新格式化我的mac处理不同的服务器环境的问题，所以我不介意重新安装一次，并重新开始，但我想尝试修复这个问题，而不这样做，如果可能的话。任何帮助是非常感谢！

***编辑***php的输出-m

$ php -m
[PHP Modules]
apcu
bcmath
bz2
calendar
Core
ctype
curl
date
dom
exif
fileinfo
filter
ftp
gd
gettext
gmp
hash
iconv
igbinary
imap
intl
json
libxml
mbstring
mcrypt
mongodb
mysqli
mysqlnd
odbc
openssl
pcntl
pcre
PDO
pdo_mysql
pdo_pgsql
pdo_sqlite
pgsql
Phar
posix
propro
raphf
readline
redis
Reflection
session
shmop
SimpleXML
soap
sockets
SPL
sqlite3
standard
sysvmsg
sysvsem
sysvshm
tidy
tokenizer
wddx
xml
xmlreader
xmlrpc
xmlwriter
xsl
Zend OPcache
zlib

[Zend Modules]
Zend OPcache