Gem::Installer#installed_specs

# File tmp/rubies/ruby-4.1.0-preview1/lib/rubygems/installer.rb, line 360
def installed_specs
  @installed_specs ||= begin
    specs = []

    Gem::SpecificationRecord.dirs_from([gem_home]).each do |dir|
      Gem::Util.glob_files_in_dir("*.gemspec", dir).each do |path|
        spec = Gem::Specification.load path
        specs << spec if spec
      end
    end

    specs
  end
end