$ cat > G << _EOF_
source 'https://rubygems.org'
gem 'ffi'
_EOF_
$ bundle install --gemfile G
Don't run Bundler as root. Installing your bundle as root will break this application for all non-root users on this machine.
Fetching gem metadata from https://rubygems.org/..                                                       
Resolving dependencies...                                                                                
Fetching ffi 1.17.2                                                                                      
Installing ffi 1.17.2 with native extensions                                                             
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.            
                                                                                                         
    current directory: /usr/lib/ruby/gems/4.0.0+0/gems/ffi-1.17.2/ext/ffi_c   
/usr/bin/ruby extconf.rb                                                                                 
checking for pkg-config for libffi... not found                                                          
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=${opt-dir}/include
        --without-opt-include
        --with-opt-lib=${opt-dir}/lib                                                                    
        --without-opt-lib                                                                                
        --with-make-prog
        --without-make-prog                                                                              
        --srcdir=.                                                                                       
        --curdir                                                                                         
        --ruby=/usr/bin/$(RUBY_BASE_NAME)                                                                
        --with-ffi_c-dir                                                                                 
        --without-ffi_c-dir                                                                              
        --with-ffi_c-include=${ffi_c-dir}/include                                                        
        --without-ffi_c-include                                                                                                                                                                                    
        --with-ffi_c-lib=${ffi_c-dir}/lib                                                                                                                                                                          
        --without-ffi_c-lib                                                                                                                                                                                        
        --enable-debug                                                                                   
        --disable-debug                                                                                                                                                                                            
        --enable-system-libffi                                                                                                                                                                                     
        --disable-system-libffi                                                                                                                                                                                    
        --with-libffi-dir                                                                                                                                                                                          
        --without-libffi-dir                                                                                                                                                                                       
        --with-libffi-include=${libffi-dir}/include                                                      
        --without-libffi-include                                                                                                                                                                                   
        --with-libffi-lib=${libffi-dir}/lib                                                              
        --without-libffi-lib                                                                                                                                                                                       
        --with-libffi-config                                                                                                                                                                                       
        --without-libffi-config
        --with-pkg-config                                                                                
        --without-pkg-config
        --with-ffi-dir
        --without-ffi-dir
        --with-ffi-include=${ffi-dir}/include
        --without-ffi-include
        --with-ffi-lib=${ffi-dir}/lib
        --without-ffi-lib
/usr/lib/ruby/4.0.0+0/mkmf.rb:528:in 'MakeMakefile#try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.

        from /usr/lib/ruby/4.0.0+0/mkmf.rb:655:in 'MakeMakefile#try_compile'
        from /usr/lib/ruby/4.0.0+0/mkmf.rb:1242:in 'block in MakeMakefile#have_header'
        from /usr/lib/ruby/4.0.0+0/mkmf.rb:1070:in 'block in MakeMakefile#checking_for'
        from /usr/lib/ruby/4.0.0+0/mkmf.rb:370:in 'block (2 levels) in MakeMakefile::Logging.postpone'
        from /usr/lib/ruby/4.0.0+0/mkmf.rb:340:in 'MakeMakefile::Logging.open'
        from /usr/lib/ruby/4.0.0+0/mkmf.rb:370:in 'block in MakeMakefile::Logging.postpone'
        from /usr/lib/ruby/4.0.0+0/mkmf.rb:340:in 'MakeMakefile::Logging.open'
        from /usr/lib/ruby/4.0.0+0/mkmf.rb:366:in 'MakeMakefile::Logging.postpone'
        from /usr/lib/ruby/4.0.0+0/mkmf.rb:1069:in 'MakeMakefile#checking_for'
        from /usr/lib/ruby/4.0.0+0/mkmf.rb:1241:in 'MakeMakefile#have_header'
        from extconf.rb:10:in 'Object#system_libffi_usable?'
        from extconf.rb:46:in '<main>'

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /usr/lib/ruby/gems/4.0.0+0/extensions/x86_64-linux-gnu/4.0.0+0/ffi-1.17.2/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /usr/lib/ruby/gems/4.0.0+0/gems/ffi-1.17.2 for inspection.
Results logged to /usr/lib/ruby/gems/4.0.0+0/extensions/x86_64-linux-gnu/4.0.0+0/ffi-1.17.2/gem_make.out

  /usr/lib/ruby/4.0.0+0/rubygems/ext/builder.rb:129:in 'Gem::Ext::Builder.run'
  /usr/lib/ruby/4.0.0+0/rubygems/ext/ext_conf_builder.rb:30:in 'Gem::Ext::ExtConfBuilder.build'
  /usr/lib/ruby/4.0.0+0/rubygems/ext/builder.rb:210:in 'Gem::Ext::Builder#build_extension'
  /usr/lib/ruby/4.0.0+0/rubygems/ext/builder.rb:244:in 'block in Gem::Ext::Builder#build_extensions'
  /usr/lib/ruby/4.0.0+0/rubygems/ext/builder.rb:241:in 'Array#each'
  /usr/lib/ruby/4.0.0+0/rubygems/ext/builder.rb:241:in 'Gem::Ext::Builder#build_extensions'
  /usr/lib/ruby/4.0.0+0/rubygems/installer.rb:808:in 'Gem::Installer#build_extensions'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/rubygems_gem_installer.rb:111:in 'Bundler::RubyGemsGemInstaller#build_extensions'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/rubygems_gem_installer.rb:30:in 'Bundler::RubyGemsGemInstaller#install'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/source/rubygems.rb:217:in 'block in Bundler::Source::Rubygems#install'
  /usr/lib/ruby/4.0.0+0/rubygems.rb:1051:in 'Gem.time'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/source/rubygems.rb:216:in 'Bundler::Source::Rubygems#install'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/installer/gem_installer.rb:54:in 'Bundler::GemInstaller#install'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/installer/gem_installer.rb:17:in 'Bundler::GemInstaller#install_from_spec'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/installer/parallel_installer.rb:133:in 'Bundler::ParallelInstaller#do_install'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/installer/parallel_installer.rb:124:in 'block in Bundler::ParallelInstaller#worker_pool'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/worker.rb:62:in 'Bundler::Worker#apply_func'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/worker.rb:57:in 'block in Bundler::Worker#process_queue'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/worker.rb:54:in 'Kernel#loop'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/worker.rb:54:in 'Bundler::Worker#process_queue'
  /usr/lib/ruby/gems/4.0.0+0/gems/bundler-4.0.0/lib/bundler/worker.rb:90:in 'block (2 levels) in Bundler::Worker#create_threads'

An error occurred while installing ffi (1.17.2), and Bundler cannot continue.

In G:
  ffi