我在使用命令sudo gem install sass通过gem安装sass时遇到问题，不幸的是我不得不通过gem进行安装。我通过npm install-g gem在系统中安装了gem。我的系统操作系统在Mac OS catalina。不知道怎么修。下面是我通过gem安装它时收到的错误消息。
sudo gem install sass
Building native extensions. This could take a while...
ERROR: Error installing sass:
ERROR: Failed to build gem native extension.
current directory: /Library/Ruby/Gems/2.6.0/gems/ffi-1.13.1/ext/ffi_c
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby -I /Library/Ruby/Site/2.6.0 -r ./siteconf20200820-26013-1wnnsu3.rb extconf.rb
checking for ffi.h... *** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.
Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/$(RUBY_BASE_NAME)
--with-ffi_c-dir
--without-ffi_c-dir
--with-ffi_c-include
--without-ffi_c-include=${ffi_c-dir}/include
--with-ffi_c-lib
--without-ffi_c-lib=${ffi_c-dir}/lib
--enable-system-libffi
--disable-system-libffi
--with-libffi-config
--without-libffi-config
--with-pkg-config
--without-pkg-config
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:467:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:585:in `block in try_compile'
from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:534:in `with_werror'
from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:585:in `try_compile'
from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:1109:in `block in have_header'
from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:959:in `block in checking_for'
from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:361:in `block (2 levels) in postpone'
from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:331:in `open'
from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:361:in `block in postpone'
from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:331:in `open'
from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:357:in `postpone'
from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:958:in `checking_for'
from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:1108:in `have_header'
from extconf.rb:10:in `system_libffi_usable?'
from extconf.rb:42:in `<main>'
To see why this extension failed to compile, please check the mkmf.log which can be found here:
/Library/Ruby/Gems/2.6.0/extensions/universal-darwin-19/2.6.0/ffi-1.13.1/mkmf.log
仍然有这个问题，但我已经通过使用Homebrew安装另一个ruby版本来解决这个问题。
但是，如果有人在没有安装自制ruby的情况下成功解决了这个问题，那就让我们知道。
需要安装包和依赖项
brew install make
brew install ruby-build
brew install ruby-completion
brew install ruby
brew install autogen
brew install libffi
brew install rvm
安装后检查环境路径。
export LDFLAGS="-L/usr/local/opt/ruby/lib"
export CPPFLAGS="-I/usr/local/opt/ruby/include"
export PKG_CONFIG_PATH="/usr/local/opt/ruby/lib/pkgconfig"
export LDFLAGS="-L/usr/local/opt/libffi/lib"
export CPPFLAGS="-I/usr/local/opt/libffi/include"
export PKG_CONFIG_PATH="/usr/local/opt/libffi/lib/pkgconfig"
现在检索您的env-shell
source ~/.zshrc