Merge remote-tracking branch 'origin/master' into gs-master

Conflicts:
 	.travis.yml
 	Gemfile.lock
 	README.md
 	app/controllers/settings/follower_domains_controller.rb
 	app/controllers/statuses_controller.rb
 	app/javascript/mastodon/locales/ja.json
 	app/lib/feed_manager.rb
 	app/models/media_attachment.rb
 	app/models/mute.rb
 	app/models/status.rb
 	app/services/mute_service.rb
 	app/views/home/index.html.haml
 	app/views/stream_entries/_simple_status.html.haml
 	config/locales/ca.yml
 	config/locales/en.yml
 	config/locales/es.yml
 	config/locales/fr.yml
 	config/locales/nl.yml
 	config/locales/pl.yml
 	config/locales/pt-BR.yml
 	config/themes.yml

app/validators/disallowed_hashtags_validator.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+class DisallowedHashtagsValidator < ActiveModel::Validator
+  def validate(status)
+    return unless status.local? && !status.reblog?
+
+    tags = Extractor.extract_hashtags(status.text)
+    tags.keep_if { |tag| disallowed_hashtags.include? tag.downcase }
+
+    status.errors.add(:text, I18n.t('statuses.disallowed_hashtags', tags: tags.join(', '), count: tags.size)) unless tags.empty?
+  end
+
+  private
+
+  def disallowed_hashtags
+    return @disallowed_hashtags if @disallowed_hashtags
+
+    @disallowed_hashtags = Setting.disallowed_hashtags.nil? ? [] : Setting.disallowed_hashtags
+    @disallowed_hashtags = @disallowed_hashtags.split(' ') if @disallowed_hashtags.is_a? String
+    @disallowed_hashtags = @disallowed_hashtags.map(&:downcase)
+  end
+end