native gem compilation fails on macOS with Ruby 4.0.0

[mscrivo]

Trying to upgrade to Ruby 4 and hitting this error when installing this gem:

Installing code_ownership 2.1.0 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    (<unknown>): found character that cannot start any token while scanning for the next token at line 1 column 10

Gem files will remain installed in /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/code_ownership-2.1.0 for inspection.
Results logged to /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/extensions/arm64-darwin-25/4.0.0/code_ownership-2.1.0/gem_make.out

  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/psych-5.3.1/lib/psych/parser.rb:62:in 'Psych::Parser#_native_parse'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/psych-5.3.1/lib/psych/parser.rb:62:in 'Psych::Parser#parse'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/psych-5.3.1/lib/psych.rb:457:in 'Psych.parse_stream'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/psych-5.3.1/lib/psych.rb:401:in 'Psych.parse'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/psych-5.3.1/lib/psych.rb:324:in 'Psych.safe_load'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/4.0.0/rubygems/safe_yaml.rb:38:in 'Gem::SafeYAML.safe_load'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/4.0.0/rubygems/ext/cargo_builder.rb:233:in 'Gem::Ext::CargoBuilder#cargo_crate_name'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/4.0.0/rubygems/ext/cargo_builder.rb:29:in 'Gem::Ext::CargoBuilder#build'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/4.0.0/rubygems/ext/builder.rb:221:in 'Gem::Ext::Builder#build_extension'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/4.0.0/rubygems/ext/builder.rb:255:in 'block in Gem::Ext::Builder#build_extensions'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/4.0.0/rubygems/ext/builder.rb:252:in 'Array#each'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/4.0.0/rubygems/ext/builder.rb:252:in 'Gem::Ext::Builder#build_extensions'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/4.0.0/rubygems/installer.rb:809:in 'Gem::Installer#build_extensions'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/rubygems_gem_installer.rb:115:in 'Bundler::RubyGemsGemInstaller#build_extensions'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/rubygems_gem_installer.rb:30:in 'Bundler::RubyGemsGemInstaller#install'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/source/rubygems.rb:217:in 'block in Bundler::Source::Rubygems#install'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/4.0.0/rubygems.rb:1051:in 'Gem.time'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/source/rubygems.rb:216:in 'Bundler::Source::Rubygems#install'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/installer/gem_installer.rb:54:in 'Bundler::GemInstaller#install'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/installer/gem_installer.rb:17:in 'Bundler::GemInstaller#install_from_spec'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/installer/parallel_installer.rb:133:in 'Bundler::ParallelInstaller#do_install'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/installer/parallel_installer.rb:124:in 'block in Bundler::ParallelInstaller#worker_pool'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/worker.rb:62:in 'Bundler::Worker#apply_func'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/worker.rb:57:in 'block in Bundler::Worker#process_queue'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/worker.rb:54:in 'Kernel#loop'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/worker.rb:54:in 'Bundler::Worker#process_queue'
  /Users/mscrivo/.local/share/mise/installs/ruby/4.0.0/lib/ruby/gems/4.0.0/gems/bundler-4.0.3/lib/bundler/worker.rb:90:in 'block (2 levels) in Bundler::Worker#create_threads'

An error occurred while installing code_ownership (2.1.0), and Bundler cannot continue.

This is on macOS 26.2, I have yet to verify if it happens on other platforms.