MakeMakefile#pkg_config

# File tmp/rubies/ruby-4.0.0/lib/mkmf.rb, line 1952
def pkg_config(pkg, *options)
  fmt = "not found"
  def fmt.%(x)
    x ? x.inspect : self
  end

  checking_for "pkg-config for #{pkg}", fmt do
    _, ldir = dir_config(pkg)
    if ldir
      pkg_config_path = "#{ldir}/pkgconfig"
      if File.directory?(pkg_config_path)
        Logging.message("PKG_CONFIG_PATH = %s\n", pkg_config_path)
        envs = ["PKG_CONFIG_PATH"=>[pkg_config_path, ENV["PKG_CONFIG_PATH"]].compact.join(File::PATH_SEPARATOR)]
      end
    end
    if pkgconfig = with_config("#{pkg}-config") and find_executable0(pkgconfig)
    # if and only if package specific config command is given
    elsif ($PKGCONFIG ||=
           (pkgconfig = with_config("pkg-config") {config_string("PKG_CONFIG") || ENV["PKG_CONFIG"] || "pkg-config"}) &&
           find_executable0(pkgconfig) && pkgconfig) and
         xsystem([*envs, $PKGCONFIG, "--exists", pkg])
      # default to pkg-config command
      pkgconfig = $PKGCONFIG
      args = [pkg]
    elsif find_executable0(pkgconfig = "#{pkg}-config")
    # default to package specific config command, as a last resort.
    else
      pkgconfig = nil
    end
    if pkgconfig
      get = proc {|opts|
        opts = Array(opts).map { |o| "--#{o}" }
        opts = xpopen([*envs, pkgconfig, *opts, *args], err:[:child, :out], &:read)
        Logging.open {puts opts.each_line.map{|s|"=> #{s.inspect}"}}
        if $?.success?
          opts = opts.strip
          libarg, libpath = LIBARG, LIBPATHFLAG.strip
          opts = opts.shellsplit.map { |s|
            if s.start_with?('-l')
              libarg % s[2..]
            elsif s.start_with?('-L')
              libpath % s[2..]
            else
              s
            end
          }.quote.join(" ")
          opts
        end
      }
    end
    orig_ldflags = $LDFLAGS
    if get and !options.empty?
      get[options]
    elsif get and try_ldflags(ldflags = get['libs'])
      if incflags = get['cflags-only-I']
        $INCFLAGS << " " << incflags
        cflags = get['cflags-only-other']
      else
        cflags = get['cflags']
      end
      libs = get['libs-only-l']
      if cflags
        $CFLAGS += " " << cflags
        $CXXFLAGS += " " << cflags
      end
      if libs
        ldflags = (Shellwords.shellwords(ldflags) - Shellwords.shellwords(libs)).quote.join(" ")
      else
        libs, ldflags = Shellwords.shellwords(ldflags).partition {|s| s =~ /-l([^ ]+)/ }.map {|l|l.quote.join(" ")}
      end
      $libs += " " << libs

      $LDFLAGS = [orig_ldflags, ldflags].join(' ')
      Logging::message "package configuration for %s\n", pkg
      Logging::message "incflags: %s\ncflags: %s\nldflags: %s\nlibs: %s\n\n",
                       incflags, cflags, ldflags, libs
      [[incflags, cflags].join(' '), ldflags, libs]
    else
      Logging::message "package configuration for %s is not found\n", pkg
      nil
    end
  end
end