feat: MiniPortile.activate_mkmf with support for pkg-config

which will set $LDFLAGS and $CFLAGS according to a set of pkg-config
files.

This should allow gems with C extensions that use mini_portile to pass
in the pkg-config files for all their build flags.

Also, accumulate directories in PKG_CONFIG_PATH so we can resolve
package references when using multiple files.

.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 = {}
 
@@ -130,12 +128,11 @@ yaml.files = [{
  url: "https://github.com/yaml/libyaml/releases/download/0.2.5/yaml-0.2.5.tar.gz",
  sha256: "c642ae9b75fee120b2d96c712538bd2cf283228d2337df2cf2988e3c02678ef4",
  }]
-recipes.push(yaml)
+recipes.unshift(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}"
+ MiniPortile.activate_mkmf(pkgconf: File.join(recipe.path, "lib", "pkgconfig", "yaml-0.1.pc"))
 
- expected = "-L" + MiniPortile.native_path(File.join(recipe.path, "lib"))
+ expected = "-L" + File.join(recipe.path, "lib")
  $LDFLAGS.split.include?(expected) or raise(<<~MSG)
  assertion failed: LDFLAGS not updated correctly:
  #{$LDFLAGS}
@@ -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
 
@@ -173,7 +171,9 @@ namespace :ports do
  puts "Artifacts of '#{recipe.name}' in '#{recipe.path}'"
  end
  puts "LIBRARY_PATH: #{ENV['LIBRARY_PATH'].inspect}"
- puts "LDFLAGS: #{ENV['LDFLAGS'].inspect}, #{$LDFLAGS.inspect}"
+ puts "LDFLAGS: #{ENV['LDFLAGS'].inspect}"
+ puts "$LDFLAGS: #{$LDFLAGS.inspect}"
+ puts "$CFLAGS: #{$CFLAGS.inspect}"
  end
 end
 

lib/mini_portile2/mini_portile.rb

@@ -94,6 +94,33 @@ def self.posix_path(path)
  end
  end
 
+ def self.activate_mkmf(pkgconf: nil)
+ if !pkgconf
+ raise NotImplementedError, "MiniPortile.activate_mkmf does not (yet) work without pkg-config files. If you want this functionality, please open an issue! ♥ ♥ ♥"
+ end
+
+ unless File.exist?(pkgconf)
+ raise RuntimeError, "pkg-config file '#{pkgconf}' does not exist"
+ end
+
+ require "mkmf"
+
+ MakeMakefile.message "Activating #{File.basename(pkgconf)} in #{File.dirname(pkgconf)}\n"
+
+ # on macos, pkg-config will not return --cflags without this
+ ENV["PKG_CONFIG_ALLOW_SYSTEM_CFLAGS"] = "t"
+
+ # append to PKG_CONFIG_PATH as we go, so later pkg-config files can depend on earlier ones
+ ENV["PKG_CONFIG_PATH"] = [ENV["PKG_CONFIG_PATH"], File.dirname(pkgconf)].compact.join(File::PATH_SEPARATOR)
+
+ cflags = minimal_pkg_config(pkgconf, "cflags")
+ $CFLAGS << " " << cflags
+ $CXXFLAGS << " " << cflags
+
+ ldflags = minimal_pkg_config(pkgconf, "libs", "static")
+ $LDFLAGS << " " << ldflags
+ end
+
  def initialize(name, version, **kwargs)
  @name = name
  @version = version
@@ -236,7 +263,13 @@ def cook
  return true
  end
 
- def activate
+ def activate(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 does not (yet) support pkg-config files. If you want this functionality, please open an issue! ♥ ♥ ♥"
+ end
+
  lib_path = File.join(port_path, "lib")
  vars = {
  'PATH' => File.join(port_path, 'bin'),
@@ -656,4 +689,34 @@ 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
+
+ #
+ # this minimal version of pkg_config is based on ruby 29dc9378 (2023-01-09)
+ #
+ # specifically with the fix from b90e56e6 to support multiple pkg-config options, and removing
+ # code paths that aren't helpful for mini-portile's use case of parsing pc files.
+ #
+ def self.minimal_pkg_config(pkg, *pcoptions)
+ if pcoptions.empty?
+ raise ArgumentError, "no pkg-config options are given"
+ end
+
+ if ($PKGCONFIG ||=
+ (pkgconfig = MakeMakefile.with_config("pkg-config") {MakeMakefile.config_string("PKG_CONFIG") || "pkg-config"}) &&
+ MakeMakefile.find_executable0(pkgconfig) && pkgconfig)
+ pkgconfig = $PKGCONFIG
+ else
+ raise RuntimeError, "pkg-config is not found"
+ end
+
+ pcoptions = Array(pcoptions).map { |o| "--#{o}" }
+ response = MakeMakefile.xpopen([pkgconfig, *pcoptions, pkg], err:[:child, :out], &:read)
+ raise RuntimeError, response unless $?.success?
+ response.strip
+ end
+ private_class_method :minimal_pkg_config
 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/libexslt.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: libexslt
+Version: 0.8.21
+Description: EXSLT Extension library
+Requires: libxml-2.0, libxslt
+Cflags: -I${includedir}
+Libs: -L${libdir} -lexslt
+Libs.private: -lm 

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 +3,18 @@
 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")
+ LIBEXSLT_PC = File.join(__dir__, "assets", "pkgconf", "libxslt", "libexslt.pc")
+
  def setup
  super
 
- @save_env = %w[PATH CPATH LIBRARY_PATH LDFLAGS].inject({}) do |env, var|
+ @save_env = %w[PATH CPATH LIBRARY_PATH LDFLAGS PKG_CONFIG_PATH].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 +26,8 @@ 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 +123,83 @@ def test_LDFLAGS_env_var_when_cross_compiling
  assert_equal(flag_elements('LDFLAGS').first, "-L#{lib_path}")
  end
 
+ def test_activate_with_pkgconf_raises_an_exception
+ assert_raises(NotImplementedError) do
+ recipe.activate(pkgconf: "fake/path/to/foo.pc")
+ end
+ end
+
+ def test_activate_mkmf_without_pkgconf_raises_an_exception
+ assert_raises(NotImplementedError) do
+ MiniPortile.activate_mkmf
+ end
+ end
+
+ def test_activate_mkmf_pkgconf_does_not_exist
+ assert_raises(RuntimeError) do
+ MiniPortile.activate_mkmf(pkgconf: "nonexistent/foo.pc")
+ end
+ end
+
+ def test_activate_mkmf_LDFLAGS_global
+ # can't get pkgconf to install on windows with ruby 2.3
+ skip if MiniPortile.windows? && RUBY_VERSION < "2.4"
+
+ MiniPortile.activate_mkmf(pkgconf: LIBXML_PC)
+
+ assert_includes($LDFLAGS.split, "-lxml2")
+ assert_includes($LDFLAGS.split, "-L/foo/libxml2/2.11.5/lib")
+ end
+
+ def test_activate_mkmf_CFLAGS_global
+ # can't get pkgconf to install on windows with ruby 2.3
+ skip if MiniPortile.windows? && RUBY_VERSION < "2.4"
+
+ MiniPortile.activate_mkmf(pkgconf: LIBXML_PC)
+
+ assert_includes($CFLAGS.split, "-I/foo/libxml2/2.11.5/include/libxml2")
+ end
+
+ def test_activate_mkmf_chains_pkgconf_path
+ # can't get pkgconf to install on windows with ruby 2.3
+ skip if MiniPortile.windows? && RUBY_VERSION < "2.4"
+
+ (ENV["PKG_CONFIG_PATH"] || "").split(File::PATH_SEPARATOR).tap do |pcpaths|
+ refute_includes(pcpaths, File.dirname(LIBXML_PC))
+ refute_includes(pcpaths, File.dirname(LIBXSLT_PC))
+ end
+
+ MiniPortile.activate_mkmf(pkgconf: LIBXML_PC)
+
+ ENV["PKG_CONFIG_PATH"].split(File::PATH_SEPARATOR).tap do |pcpaths|
+ assert_includes(pcpaths, File.dirname(LIBXML_PC))
+ refute_includes(pcpaths, File.dirname(LIBXSLT_PC))
+ end
+
+ MiniPortile.activate_mkmf(pkgconf: LIBXSLT_PC)
+
+ ENV["PKG_CONFIG_PATH"].split(File::PATH_SEPARATOR).tap do |pcpaths|
+ assert_includes(pcpaths, File.dirname(LIBXML_PC))
+ assert_includes(pcpaths, File.dirname(LIBXSLT_PC))
+ end
+
+ MiniPortile.activate_mkmf(pkgconf: LIBEXSLT_PC)
+
+ $CFLAGS.split.tap do |cflags|
+ assert_includes(cflags, "-I/foo/libxml2/2.11.5/include/libxml2")
+ assert_includes(cflags, "-I/foo/libxslt/1.1.38/include")
+ end
+ $LDFLAGS.split.tap do |ldflags|
+ assert_includes(ldflags, "-L/foo/libxml2/2.11.5/lib")
+ assert_includes(ldflags, "-lxml2")
+ assert_includes(ldflags, "-L/foo/libxslt/1.1.38/lib")
+ assert_includes(ldflags, "-lxslt")
+ assert_includes(ldflags, "-lexslt")
+ assert_includes(ldflags, "-L/foo/zlib/1.3/lib") # from `--static`
+ assert_includes(ldflags, "-lz") # from `--static`
+ end
+ end
+
  private
 
  def path_elements(varname)