composer安装报错：No composer.lock file present.

问题：
No composer.lock file present. Updating dependencies to latest instead of installing from lock file. See https://getcomposer.org/install for more information.
Loading composer repositories with package information
Updating dependencies
Your requirements could not be resolved to an installable set of packages.

解决：

composer install --ignore-platform-reqs

忽略版本即可