Use ENV variables to set conf paths (#222)

closes: GH-202

Instead of creating `.rake-compiler-siteconf.rb` to override
`RbConfig::MAKEFILE_CONFIG` and `RbConfig::CONFIG`, set environment
variables to `make install` command. Since `RbConfig` is suppose to be
readonly, we shouldn't overwrite its values.

Additionally, this update addresses a bug caused by
`.rake-compiler-siteconf.rb`. The file's hardcoded destination path
causes `rake-compiler` to consistently create files in that location,
even if the project is renamed or moved. Consequently, changes to the
gem project's path do not trigger the file task to update the file. This
fix resolves this issue.

---------

Co-authored-by: Sutou Kouhei <kou@clear-code.com>

lib/rake/extensiontask.rb

@@ -1,4 +1,5 @@
 require "rbconfig"
+require "shellwords"
 
 require 'rake/baseextensiontask'
 require "rubygems/package_task"
@@ -79,7 +80,7 @@ def cross_config_options(for_platform=nil)
       end.flatten
     end
 
-    def make_makefile_cmd(root_path, tmp_path, extconf, siteconf_path, cross_platform) # :nodoc:
+    def make_makefile_cmd(root_path, tmp_path, extconf, cross_platform) # :nodoc:
       # include current directory
       include_dirs = ['.'].concat(@config_includes).uniq.join(File::PATH_SEPARATOR)
 
@@ -89,7 +90,7 @@ def make_makefile_cmd(root_path, tmp_path, extconf, siteconf_path, cross_platfor
       rel_extconf = abs_extconf.relative_path_from(abs_tmp_path).to_s
 
       # base command
-      cmd = [Gem.ruby, "-I#{include_dirs}", "-r#{File.basename(siteconf_path)}", rel_extconf]
+      cmd = [Gem.ruby, "-I#{include_dirs}", rel_extconf]
 
       # add all the options
       cmd += @config_options
@@ -140,7 +141,6 @@ def define_compile_tasks(for_platform = nil, ruby_ver = RUBY_VERSION)
       tmp_path = "#{@tmp_dir}/#{platf}/#{@name}/#{ruby_ver}"
       stage_path = "#{@tmp_dir}/#{platf}/stage"
 
-      siteconf_path = "#{tmp_path}/.rake-compiler-siteconf.rb"
       tmp_binary_path = "#{tmp_path}/#{binary_path}"
       tmp_binary_dir_path = File.dirname(tmp_binary_path)
       stage_binary_path = "#{stage_path}/#{lib_binary_path}"
@@ -158,26 +158,20 @@ def define_compile_tasks(for_platform = nil, ruby_ver = RUBY_VERSION)
       directory lib_path
       directory stage_binary_dir_path
 
-      directory File.dirname(siteconf_path)
-      # Set paths for "make install" destinations
-      file siteconf_path => File.dirname(siteconf_path) do
-        File.open(siteconf_path, "w") do |siteconf|
-          siteconf.puts "require 'rbconfig'"
-          siteconf.puts "require 'mkmf'"
-          siteconf.puts "dest_path = mkintpath(#{File.expand_path(lib_path).dump})"
-          %w[sitearchdir sitelibdir].each do |dir|
-            siteconf.puts "RbConfig::MAKEFILE_CONFIG['#{dir}'] = dest_path"
-            siteconf.puts "RbConfig::CONFIG['#{dir}'] = dest_path"
-          end
-        end
-      end
-
       # copy binary from temporary location to final lib
       # tmp/extension_name/extension_name.{so,bundle} => lib/
       task "copy:#{@name}:#{platf}:#{ruby_ver}" => [lib_path, tmp_binary_path, "#{tmp_path}/Makefile"] do
         # install in lib for native platform only
         unless for_platform
-          sh "#{make} install target_prefix=", chdir: tmp_path
+          relative_lib_path = Pathname(lib_path).relative_path_from(tmp_path)
+
+          make_command_line = Shellwords.shellsplit(make)
+          make_command_line << "install"
+          make_command_line << "sitearchdir=#{relative_lib_path}"
+          make_command_line << "sitelibdir=#{relative_lib_path}"
+          make_command_line << "target_prefix="
+
+          sh(*make_command_line, chdir: tmp_path)
         end
       end
       # copy binary from temporary location to staging directory
@@ -207,14 +201,14 @@ def define_compile_tasks(for_platform = nil, ruby_ver = RUBY_VERSION)
 
       # makefile depends of tmp_dir and config_script
       # tmp/extension_name/Makefile
-      file "#{tmp_path}/Makefile" => [tmp_path, extconf, siteconf_path] do |t|
+      file "#{tmp_path}/Makefile" => [tmp_path, extconf] do |t|
         if t.prerequisites.include?("#{tmp_path}/fake.rb")
           cross_platform = platf
         else
           cross_platform = nil
         end
 
-        command = make_makefile_cmd(Dir.pwd, tmp_path, extconf, siteconf_path, cross_platform)
+        command = make_makefile_cmd(Dir.pwd, tmp_path, extconf, cross_platform)
 
         chdir tmp_path do
           sh(*command)

spec/lib/rake/extensiontask_spec.rb

@@ -289,7 +289,6 @@
       around :each do |test|
         @tmp_path = "injectedtmp"
         @extconf = "injectedextconf.rb"
-        @siteconf_path = "#{@tmp_path}/.injected-siteconf.rb"
 
         Dir.mktmpdir do |root_path|
           @root_path = root_path
@@ -313,13 +312,12 @@
       end
 
       it "runs the extconf with proper arguments when not cross-compiling" do
-        command = @ext.make_makefile_cmd(@root_path, @tmp_path, @extconf, @siteconf_path, nil)
+        command = @ext.make_makefile_cmd(@root_path, @tmp_path, @extconf, nil)
 
         expected_includes = [".", "/injected/include1", "/injected/include2"].join(File::PATH_SEPARATOR)
         expected = [
           Gem.ruby,
           "-I#{expected_includes}",
-          "-r.injected-siteconf.rb",
           "../#{@extconf}",
           "--with-a", # config_options
           "--", "--with-b", # extra_options
@@ -329,13 +327,12 @@
       end
 
       it "runs the extconf with proper arguments when cross-compiling" do
-        command = @ext.make_makefile_cmd(@root_path, @tmp_path, @extconf, @siteconf_path, "universal-known")
+        command = @ext.make_makefile_cmd(@root_path, @tmp_path, @extconf, "universal-known")
 
         expected_includes = [".", "/injected/include1", "/injected/include2"].join(File::PATH_SEPARATOR)
         expected = [
           Gem.ruby,
           "-I#{expected_includes}",
-          "-r.injected-siteconf.rb",
           "../#{@extconf}",
           "--with-a", # config_options
           "--with-c", "--with-d", # cross_config_options
@@ -348,13 +345,12 @@
       it "handles spaces in arguments correctly" do
         @ext.extra_options << "--with-spaces='a b'"
 
-        command = @ext.make_makefile_cmd(@root_path, @tmp_path, @extconf, @siteconf_path, nil)
+        command = @ext.make_makefile_cmd(@root_path, @tmp_path, @extconf, nil)
 
         expected_includes = [".", "/injected/include1", "/injected/include2"].join(File::PATH_SEPARATOR)
         expected = [
           Gem.ruby,
           "-I#{expected_includes}",
-          "-r.injected-siteconf.rb",
           "../#{@extconf}",
           "--with-a", # config_options
           "--", "--with-b", "--with-spaces='a b'", # extra_options
@@ -366,13 +362,12 @@
       it "handles 'nil' in the command array gracefully" do
         @ext.config_options << nil # imagine this is ENV['NONEXISTENT_VALUE']
 
-        command = @ext.make_makefile_cmd(@root_path, @tmp_path, @extconf, @siteconf_path, nil)
+        command = @ext.make_makefile_cmd(@root_path, @tmp_path, @extconf, nil)
 
         expected_includes = [".", "/injected/include1", "/injected/include2"].join(File::PATH_SEPARATOR)
         expected = [
           Gem.ruby,
           "-I#{expected_includes}",
-          "-r.injected-siteconf.rb",
           "../#{@extconf}",
           "--with-a", # config_options
           "--", "--with-b", # extra_options