cocoapods安装报错rubygems/core_ext/kernel_warn (LoadError)，求解决！！！

/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in require': cannot load such file -- rubygems/core_ext/kernel_warn (LoadError)
from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:inrequire'
from /Library/Ruby/Site/2.3.0/rubygems.rb:1395:in '
from :4:inrequire' from :4:in `'
Macbook air 10.14.2系统
ruby 2.3.7p456 (2018-03-28 revision 63024) [universal.x86_64-darwin18]
大神，这个怎么处理，已经困扰了很久了。

可以试下这个 sudo gem update --system 2.7.4
来自:https://stackoverflow.com/questions/53856625/ruby-error-after-upgrading-os-to-mojave-and-installing-xcode-10-1
我把mac 系统升级到最新的了, 反正我就做了这两件事就好了