make the setup script generated by the standalone instalation multipl…

…atform

bundler/lib/bundler/installer/standalone.rb

@@ -14,6 +14,7 @@ def generate
         file.puts "require 'rbconfig'"
         file.puts define_path_helpers
         file.puts reverse_rubygems_kernel_mixin
+        file.puts add_arch_formatter
         paths.each do |path|
           if Pathname.new(path).absolute?
             file.puts %($:.unshift "#{path}")
@@ -32,7 +33,7 @@ def paths
         Array(spec.require_paths).map do |path|
           gem_path(path, spec).
             sub(version_dir, '#{RUBY_ENGINE}/#{Gem.ruby_api_version}').
-            sub(extensions_dir, 'extensions/\k<platform>/#{Gem.extension_api_version}')
+            sub(extensions_dir, 'extensions/#{local_platform}/#{Gem.extension_api_version}')
           # This is a static string intentionally. It's interpolated at a later time.
         end
       end.flatten.compact
@@ -99,5 +100,68 @@ def reverse_rubygems_kernel_mixin
       end
       END
     end
+
+    def add_arch_formatter
+      <<~'END'
+        def local_platform
+          arch = RbConfig::CONFIG["arch"]
+          arch = "#{arch}_60" if arch =~ /mswin(?:32|64)$/
+
+          arch = arch.split "-"
+
+          if arch.length > 2 && arch.last !~ /\d+(\.\d+)?$/ # reassemble x86-linux-{libc}
+            extra = arch.pop
+            arch.last << "-#{extra}"
+          end
+
+          cpu = arch.shift
+
+          formated_cpu = case cpu
+                         when /i\d86/ then "x86"
+                         else cpu
+                         end
+
+          if arch.length == 2 && arch.last =~ /^\d+(\.\d+)?$/ # for command-line
+            formated_os, formated_version = arch
+            return
+          end
+
+          os, = arch
+          if os.nil?
+            formated_cpu = nil
+            os = cpu
+          end # legacy jruby
+
+          formated_os, formated_version = case os
+                                          when /aix(\d+)?/ then             ["aix",       $1]
+                                          when /cygwin/ then                ["cygwin",    nil]
+                                          when /darwin(\d+)?/ then          ["darwin",    $1]
+                                          when /^macruby$/ then             ["macruby",   nil]
+                                          when /freebsd(\d+)?/ then         ["freebsd",   $1]
+                                          when /^java$/, /^jruby$/ then     ["java",      nil]
+                                          when /^java([\d.]*)/ then         ["java",      $1]
+                                          when /^dalvik(\d+)?$/ then        ["dalvik",    $1]
+                                          when /^dotnet$/ then              ["dotnet",    nil]
+                                          when /^dotnet([\d.]*)/ then       ["dotnet",    $1]
+                                          when /linux-?(\w+)?/ then         ["linux",     $1]
+                                          when /mingw32/ then               ["mingw32",   nil]
+                                          when /mingw-?(\w+)?/ then         ["mingw",     $1]
+                                          when /(mswin\d+)(\_(\d+))?/ then
+                                            os = $1
+                                            version = $3
+                                            formated_cpu = "x86" if formated_cpu.nil? && os =~ /32$/
+                                            [os, version]
+                                          when /netbsdelf/ then             ["netbsdelf", nil]
+                                          when /openbsd(\d+\.\d+)?/ then    ["openbsd",   $1]
+                                          when /solaris(\d+\.\d+)?/ then    ["solaris",   $1]
+                                          # test
+                                          when /^(\w+_platform)(\d+)?/ then [$1,          $2]
+                                          else ["unknown", nil]
+                                          end
+
+          [formated_cpu, formated_os, formated_version].compact.join "-"
+        end
+      END
+    end
   end
 end

bundler/spec/install/gems/standalone_spec.rb

@@ -244,16 +244,34 @@
 
       expect(script_content).to include("def self.ruby_api_version")
       expect(script_content).to include("def self.extension_api_version")
+      expect(script_content).to include("def local_platform")
     end
 
     it "generates a bundle/bundler/setup.rb with the proper paths" do
       expected_path = bundled_app("bundle/bundler/setup.rb")
       script_content = File.read(expected_path)
       extension_line = script_content.each_line.find {|line| line.include? "/extensions/" }.strip
-      platform = Gem::Platform.local
 
-      expect(extension_line).to start_with '$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions/'
-      expect(extension_line).to end_with platform.to_s + '/#{Gem.extension_api_version}/very_simple_binary-1.0")'
+      expect(
+        extension_line
+      ).to eq('$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions' \
+              '/#{local_platform}/#{Gem.extension_api_version}/very_simple_binary-1.0")')
+    end
+
+    # Our CI has steps for several platforms, so each step Gem::Platform.local will return a different
+    # value and in the end we'll test multiple platforms.
+    it "generates a bundle/bundler/setup.rb that is multiplatform" do
+      local_platform = Gem::Platform.local
+      native_extension_pattern = %r{#{local_platform}/.+/very_simple_binary-1.0}
+
+      ruby <<-RUBY
+        require "./bundle/bundler/setup"
+
+        puts $:
+      RUBY
+
+      expect(out).to match(native_extension_pattern)
+      expect(err).to be_empty
     end
   end
 

lib/rubygems/platform.rb

@@ -69,7 +69,7 @@ def initialize(arch)
     case arch
     when Array then
       @cpu, @os, @version = arch
-    when String then
+    when String then # Update Bundler::Standalone#add_arch_formatter whenever this case is changed.
       arch = arch.split "-"
 
       if arch.length > 2 && arch.last !~ /\d+(\.\d+)?$/ # reassemble x86-linux-{libc}