Merge pull request #382 from ruby-protobuf/ah/compile_with_protoc_3

Update the compile task to work with protoc v3

Author: liveh2o

lib/protobuf/tasks/compile.rake

@@ -1,13 +1,32 @@
-require 'fileutils'
+require "fileutils"
 
 namespace :protobuf do
 
-  desc 'Clean & Compile the protobuf source to ruby classes. Pass PB_NO_CLEAN=1 if you do not want to force-clean first.'
+  desc "Clean & Compile the protobuf source to ruby classes. Pass PB_NO_CLEAN=1 if you do not want to force-clean first."
   task :compile, [:package, :source, :destination, :plugin, :file_extension] do |_tasks, args|
-    args.with_defaults(:destination => 'lib')
-    args.with_defaults(:source => 'definitions')
-    args.with_defaults(:plugin => 'ruby')
-    args.with_defaults(:file_extension => '.pb.rb')
+    binpath = ::File.expand_path("../../../../bin", __FILE__)
+
+    args.with_defaults(:destination => "lib")
+    args.with_defaults(:source => "definitions")
+    args.with_defaults(:plugin => "protoc-gen-ruby-protobuf=#{binpath}/protoc-gen-ruby")
+    args.with_defaults(:file_extension => ".pb.rb")
+
+    # The local Ruby generator collides with the builtin Ruby generator
+    #
+    # From the protoc docs:
+    #
+    #   --plugin=EXECUTABLE
+    #
+    #   ...EXECUTABLE may be of the form NAME=PATH, in which case the given plugin name
+    #   is mapped to the given executable even if the executable"s own name differs.
+    #
+    # Use the NAME=PATH form to specify an alternative plugin name that avoids the name collision
+    #
+    plugin_name, _plugin_path = args[:plugin].split("=")
+
+    # The plugin name MUST have the protoc-gen- prefix in order to work, but that prefix is dropped
+    # when using the plugin to generate definitions
+    plugin_name.gsub!("protoc-gen-", "")
 
     unless do_not_clean?
       force_clean!
@@ -16,22 +35,23 @@ namespace :protobuf do
 
     command = []
     command << "protoc"
-    command << "--#{args[:plugin]}_out=#{args[:destination]}"
+    command << "--plugin=#{args[:plugin]}"
+    command << "--#{plugin_name}_out=#{args[:destination]}"
     command << "-I #{args[:source]}"
     command << Dir["#{args[:source]}/#{args[:package]}/**/*.proto"].join(" ")
-    full_command = command.join(' ')
+    full_command = command.join(" ")
 
     puts full_command
     system(full_command)
   end
 
-  desc 'Clean the generated *.pb.rb files from the destination package. Pass PB_FORCE_CLEAN=1 to skip confirmation step.'
+  desc "Clean the generated *.pb.rb files from the destination package. Pass PB_FORCE_CLEAN=1 to skip confirmation step."
   task :clean, [:package, :destination, :file_extension] do |_task, args|
-    args.with_defaults(:destination => 'lib')
-    args.with_defaults(:file_extension => '.pb.rb')
+    args.with_defaults(:destination => "lib")
+    args.with_defaults(:file_extension => ".pb.rb")
 
-    file_extension = args[:file_extension].sub(/\*?\.+/, '')
-    files_to_clean = ::File.join(args[:destination], args[:package], '**', "*.#{file_extension}")
+    file_extension = args[:file_extension].sub(/\*?\.+/, "")
+    files_to_clean = ::File.join(args[:destination], args[:package], "**", "*.#{file_extension}")
 
     if force_clean? || permission_to_clean?(files_to_clean)
       ::Dir.glob(files_to_clean).each do |file|
@@ -41,15 +61,15 @@ namespace :protobuf do
   end
 
   def do_not_clean?
-    ! ::ENV.key?('PB_NO_CLEAN')
+    ! ::ENV.key?("PB_NO_CLEAN")
   end
 
   def force_clean?
-    ::ENV.key?('PB_FORCE_CLEAN')
+    ::ENV.key?("PB_FORCE_CLEAN")
   end
 
   def force_clean!
-    ::ENV['PB_FORCE_CLEAN'] = '1'
+    ::ENV["PB_FORCE_CLEAN"] = "1"
   end
 
   def permission_to_clean?(files_to_clean)