Error installing rails. Rails doesn't work

Question

ローカルでrailsを実行していましたが動かなくなってしまいました。エラーなど調べてみましたが解決方法がわかりません。
どなたか分かる方いらっしゃいますか？

ERROR: Error installing rails: ERROR: Failed to build gem native extension.

zshrc
   
   # System-wide profile for interactive zsh(1) shells.
   
   # Setup user specific overrides for this in ~/.zshrc. See zshbuiltins(1)
   # and zshoptions(1) for more details.
   
   # Correctly display UTF-8 with combining characters.
   if [[ "$(locale LC_CTYPE)" == "UTF-8" ]]; then
       setopt COMBINING_CHARS
   fi
   
   # Disable the log builtin, so we don't conflict with /usr/bin/log
   disable log
   
   # Save command history
   HISTFILE=${ZDOTDIR:-$HOME}/.zsh_history
   HISTSIZE=2000
   SAVEHIST=1000
   
   # Beep on error
   setopt BEEP
   
   # Use keycodes (generated via zkbd) if present, otherwise fallback on
   # values from terminfo
   if [[ -r ${ZDOTDIR:-$HOME}/.zkbd/${TERM}-${VENDOR} ]] ; then
       source ${ZDOTDIR:-$HOME}/.zkbd/${TERM}-${VENDOR}
   else
       typeset -g -A key
   
       [[ -n "$terminfo[kf1]" ]] && key[F1]=$terminfo[kf1]
       [[ -n "$terminfo[kf2]" ]] && key[F2]=$terminfo[kf2]
       [[ -n "$terminfo[kf3]" ]] && key[F3]=$terminfo[kf3]
       [[ -n "$terminfo[kf4]" ]] && key[F4]=$terminfo[kf4]
       [[ -n "$terminfo[kf5]" ]] && key[F5]=$terminfo[kf5]
       [[ -n "$terminfo[kf6]" ]] && key[F6]=$terminfo[kf6]
       [[ -n "$terminfo[kf7]" ]] && key[F7]=$terminfo[kf7]
       [[ -n "$terminfo[kf8]" ]] && key[F8]=$terminfo[kf8]
       [[ -n "$terminfo[kf9]" ]] && key[F9]=$terminfo[kf9]
       [[ -n "$terminfo[kf10]" ]] && key[F10]=$terminfo[kf10]
       [[ -n "$terminfo[kf11]" ]] && key[F11]=$terminfo[kf11]
       [[ -n "$terminfo[kf12]" ]] && key[F12]=$terminfo[kf12]
       [[ -n "$terminfo[kf13]" ]] && key[F13]=$terminfo[kf13]
       [[ -n "$terminfo[kf14]" ]] && key[F14]=$terminfo[kf14]
       [[ -n "$terminfo[kf15]" ]] && key[F15]=$terminfo[kf15]
       [[ -n "$terminfo[kf16]" ]] && key[F16]=$terminfo[kf16]
       [[ -n "$terminfo[kf17]" ]] && key[F17]=$terminfo[kf17]
       [[ -n "$terminfo[kf18]" ]] && key[F18]=$terminfo[kf18]
       [[ -n "$terminfo[kf19]" ]] && key[F19]=$terminfo[kf19]
       [[ -n "$terminfo[kf20]" ]] && key[F20]=$terminfo[kf20]
       [[ -n "$terminfo[kbs]" ]] && key[Backspace]=$terminfo[kbs]
       [[ -n "$terminfo[kich1]" ]] && key[Insert]=$terminfo[kich1]
       [[ -n "$terminfo[kdch1]" ]] && key[Delete]=$terminfo[kdch1]
       [[ -n "$terminfo[khome]" ]] && key[Home]=$terminfo[khome]
       [[ -n "$terminfo[kend]" ]] && key[End]=$terminfo[kend]
       [[ -n "$terminfo[kpp]" ]] && key[PageUp]=$terminfo[kpp]
       [[ -n "$terminfo[knp]" ]] && key[PageDown]=$terminfo[knp]
       [[ -n "$terminfo[kcuu1]" ]] && key[Up]=$terminfo[kcuu1]
       [[ -n "$terminfo[kcub1]" ]] && key[Left]=$terminfo[kcub1]
       [[ -n "$terminfo[kcud1]" ]] && key[Down]=$terminfo[kcud1]
       [[ -n "$terminfo[kcuf1]" ]] && key[Right]=$terminfo[kcuf1]
   fi
   
   # Default key bindings
   [[ -n ${key[Delete]} ]] && bindkey "${key[Delete]}" delete-char
   [[ -n ${key[Home]} ]] && bindkey "${key[Home]}" beginning-of-line
   [[ -n ${key[End]} ]] && bindkey "${key[End]}" end-of-line
   [[ -n ${key[Up]} ]] && bindkey "${key[Up]}" up-line-or-search
   [[ -n ${key[Down]} ]] && bindkey "${key[Down]}" down-line-or-search
   
   # Default prompt
   PS1="%n@%m %1~ %# "
   
   # Useful support for interacting with Terminal.app or other terminal programs
   [ -r "/etc/zshrc_$TERM_PROGRAM" ] && . "/etc/zshrc_$TERM_PROGRAM"

///

    menu_app % rails c
    Rails is not currently installed on this system. To get the latest version, simply type:
    
        $ sudo gem install rails
    
    You can then rerun your "rails" command.
    menu_app % sudo gem install rails
    Building native extensions. This could take a while...
    ERROR:  Error installing rails:
            ERROR: Failed to build gem native extension.
    
        current directory: /Library/Ruby/Gems/2.6.0/gems/nio4r-2.5.7/ext/nio4r
    /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby -I /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0 -r ./siteconf20210312-73902-1t6sq6o.rb extconf.rb
    checking for unistd.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)
    /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:15: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/nio4r-2.5.7/mkmf.log
    
    extconf failed, exit code 1
    
    Gem files will remain installed in /Library/Ruby/Gems/2.6.0/gems/nio4r-2.5.7 for inspection.
    Results logged to /Library/Ruby/Gems/2.6.0/extensions/universal-darwin-19/2.6.0/nio4r-2.5.7/gem_make.out
    menu_app % 

Comments

[technocore]

/etc/zshrcファイルの内容をわざわざ質問文に載せる理由はなんでしょうか？
どこかをご自分で編集したのでしょうか？

Answer 1

`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/nio4r-2.5.7/mkmf.log

`
とあります。
このlogを確認してください。
大抵最後にヒントやこのようにして　と助言が書かれています