feat: introduce activate(mkmf: true) with support for pkg-config

which will set $LDFLAGS and $CFLAGS according to the pkg-config file

This should allow gems with C extensions that use mini_portile to pass
in the pkg-config and everything should just work.

.gitignore

@@ -3,3 +3,4 @@ Gemfile.lock
 pkg
 ports
 tmp
+mkmf.log

examples/Rakefile

@@ -3,8 +3,6 @@ require 'rbconfig'
 $: << File.expand_path(File.join(File.dirname(__FILE__), "../lib"))
 require "mini_portile2"
 
-require "mkmf"
-
 recipes = []
 recipe_hooks = {}
 
@@ -132,8 +130,7 @@ yaml.files = [{
  }]
 recipes.push(yaml)
 recipe_hooks["yaml"] = lambda do |recipe|
- conf = pkg_config(File.join(recipe.path, "lib", "pkgconfig", "yaml-0.1.pc"))
- puts "pkg_config: #{conf.inspect}"
+ recipe.activate_mkmf(pkgconf: File.join(recipe.path, "lib", "pkgconfig", "yaml-0.1.pc"))
 
  expected = "-L" + MiniPortile.native_path(File.join(recipe.path, "lib"))
  $LDFLAGS.split.include?(expected) or raise(<<~MSG)
@@ -158,9 +155,10 @@ namespace :ports do
  desc "Install port #{recipe.name} #{recipe.version}"
  task recipe.name => ["ports"] do |t|
  recipe.cook
- recipe.activate
  if hook = recipe_hooks[recipe.name]
  hook.call(recipe)
+ else
+ recipe.activate
  end
  end
 

lib/mini_portile2/mini_portile.rb

@@ -236,7 +236,21 @@ def cook
  return true
  end
 
- def activate
+ def activate(mkmf: false, pkgconf: nil)
+ if mkmf
+ activate_mkmf(pkgconf:)
+ else
+ activate_classic(pkgconf:)
+ end
+ end
+
+ def activate_classic(pkgconf: nil)
+ if pkgconf
+ # because I don't know if anybody has this use case,
+ # I just haven't bothered to implement this yet.
+ raise NotImplementedError, "MiniPortile#activate classic does not yet support a pkgconf. If you want this functionality, please open an issue! ♥ ♥ ♥"
+ end
+
  lib_path = File.join(port_path, "lib")
  vars = {
  'PATH' => File.join(port_path, 'bin'),
@@ -268,6 +282,33 @@ def activate
  end
  end
 
+ def activate_mkmf(pkgconf: nil)
+ if !pkgconf
+ raise NotImplementedError, "MiniPortile#activate for mkmf does not yet work without a pkgconf. If you want this functionality, please open an issue! ♥ ♥ ♥"
+ end
+
+ unless File.exist?(pkgconf)
+ raise RuntimeError, "pkg-config file '#{pkgconf}' does not exist"
+ end
+
+ output "Activating #{@name} #{@version} using #{pkgconf} ..."
+
+ require_relative "mkmf_patches"
+
+ # on macos, pkg-config will not return --cflags without this
+ ENV["PKG_CONFIG_ALLOW_SYSTEM_CFLAGS"] = "t"
+
+ cflags = MakeMakefile.pkg_config(pkgconf, "cflags")
+ ldflags = MakeMakefile.pkg_config(pkgconf, "libs", "static")
+
+ MakeMakefile.append_cflags(cflags)
+ MakeMakefile.append_ldflags(ldflags)
+
+ # make sure future calls to activate_mkmf are able to find this pkg-config
+ # e.g., in nokogiri, the libxslt pc file references libxml2
+ ENV["PKG_CONFIG_PATH"] = "#{native_path(File.dirname(pkgconf))}#{File::PATH_SEPARATOR}#{ENV["PKG_CONFIG_PATH"]}"
+ end
+
  def path
  File.expand_path(port_path)
  end
@@ -656,4 +697,8 @@ def with_tempfile(filename, full_path)
  FileUtils.mkdir_p File.dirname(full_path)
  FileUtils.mv temp_file.path, full_path, :force => true
  end
+
+ def abort_pkg_config(id)
+ abort("\nCould not configure the build properly (#{id}). Please install either the `pkg-config` utility or the `pkg-config` rubygem.\n\n")
+ end
 end

lib/mini_portile2/mkmf_patches.rb

@@ -0,0 +1,81 @@
+# frozen-string-literal: false
+
+require "mkmf"
+
+module MakeMakefile
+ #
+ # this version of pkg_config is taken from ruby 29dc9378 (2023-01-09)
+ #
+ # specifically with the fix from b90e56e6 to support multiple pkg-config options
+ #
+ 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") || "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}"}}
+ opts.strip if $?.success?
+ }
+ 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
+end

test/assets/pkgconf/libxml2/libxml-2.0.pc

@@ -0,0 +1,13 @@
+prefix=/foo/libxml2/2.11.5
+exec_prefix=${prefix}
+libdir=/foo/libxml2/2.11.5/lib
+includedir=${prefix}/include
+modules=1
+
+Name: libXML
+Version: 2.11.5
+Description: libXML library version2.
+Requires:
+Libs: -L${libdir} -lxml2
+Libs.private: -L/foo/zlib/1.3/lib -lz -lm 
+Cflags: -I${includedir}/libxml2 

test/assets/pkgconf/libxslt/libxslt.pc

@@ -0,0 +1,13 @@
+prefix=/foo/libxslt/1.1.38
+exec_prefix=${prefix}
+libdir=/foo/libxslt/1.1.38/lib
+includedir=${prefix}/include
+
+
+Name: libxslt
+Version: 1.1.38
+Description: XSLT library version 2.
+Requires: libxml-2.0
+Cflags: -I${includedir}
+Libs: -L${libdir} -lxslt
+Libs.private: -lm

test/test_activate.rb

@@ -3,14 +3,17 @@
 class TestActivate < TestCase
  attr_reader :recipe
 
+ LIBXML_PC = File.join(__dir__, "assets", "pkgconf", "libxml2", "libxml-2.0.pc")
+ LIBXSLT_PC = File.join(__dir__, "assets", "pkgconf", "libxslt", "libxslt.pc")
+
  def setup
  super
 
  @save_env = %w[PATH CPATH LIBRARY_PATH LDFLAGS].inject({}) do |env, var|
  env.update(var => ENV[var])
  end
- $LDFLAGS = nil
- $CPPFLAGS = nil
+ $LDFLAGS = ""
+ $CFLAGS = ""
 
  FileUtils.rm_rf(["tmp", "ports"]) # remove any previous test files
 
@@ -22,8 +25,8 @@ def setup
  def teardown
  FileUtils.rm_rf(["tmp", "ports"]) # remove any previous test files
 
- $LDFLAGS = nil
- $CPPFLAGS = nil
+ $LDFLAGS = ""
+ $CFLAGS = ""
  @save_env.each do |var, val|
  ENV[var] = val
  end
@@ -119,6 +122,55 @@ def test_LDFLAGS_env_var_when_cross_compiling
  assert_equal(flag_elements('LDFLAGS').first, "-L#{lib_path}")
  end
 
+ def test_activate_classic_with_pkgconf_raises_an_exception
+ assert_raises(NotImplementedError) do
+ recipe.activate(pkgconf: "fake/path/to/foo.pc")
+ end
+
+ assert_raises(NotImplementedError) do
+ recipe.activate_classic(pkgconf: "fake/path/to/foo.pc")
+ end
+ end
+
+ def test_activate_mkmf_without_pkgconf_raises_an_exception
+ assert_raises(NotImplementedError) do
+ recipe.activate(mkmf: true)
+ end
+
+ assert_raises(NotImplementedError) do
+ recipe.activate_mkmf
+ end
+ end
+
+ def test_activate_mkmf_pkgconf_does_not_exist
+ assert_raises(RuntimeError) do
+ recipe.activate(mkmf: true, pkgconf: "nonexistent/foo.pc")
+ end
+ end
+
+ def test_activate_mkmf_LDFLAGS_global
+ recipe.activate(mkmf: true, pkgconf: LIBXML_PC)
+
+ assert_includes($LDFLAGS.split, "-lxml2")
+ assert_includes($LDFLAGS.split, "-L#{MiniPortile.native_path("/foo/libxml2/2.11.5/lib")}")
+ end
+
+ def test_activate_mkmf_CFLAGS_global
+ recipe.activate(mkmf: true, pkgconf: LIBXML_PC)
+
+ assert_includes($CFLAGS.split, "-I#{MiniPortile.native_path("/foo/libxml2/2.11.5/include/libxml2")}")
+ end
+
+ def test_activate_mkmf_chains_pkgconf_path
+ recipe.activate(mkmf: true, pkgconf: LIBXML_PC)
+ recipe.activate(mkmf: true, pkgconf: LIBXSLT_PC)
+
+ xmlflags = $LDFLAGS.split.select { |v| v == "-L#{MiniPortile.native_path("/foo/libxml2/2.11.5/lib")}" }
+
+ # the -L from both libxml and libxslt should be present
+ assert_equal(2, xmlflags.size)
+ end
+
  private
 
  def path_elements(varname)