Safely load gem plugin. Avoid stackoverflow if other versions of YARD…

… are present.

lib/rubygems_plugin.rb

@@ -14,7 +14,6 @@ def has_yardoc
     @has_rdoc == 'yard'
   end
 
-  undef has_rdoc? # redefining
   def has_rdoc?
     @has_rdoc && @has_rdoc != 'yard'
   end
@@ -43,18 +42,16 @@ def run_yardoc(*args)
   rescue Errno::EACCES => e
     dirname = File.dirname e.message.split("-")[1].strip
     raise Gem::FilePermissionError.new(dirname)
-  rescue RuntimeError => ex
+  rescue => ex
     alert_error "While generating documentation for #{@spec.full_name}"
     ui.errs.puts "... MESSAGE:   #{ex}"
     ui.errs.puts "... YARDDOC args: #{args.join(' ')}"
-    ui.errs.puts "\t#{ex.backtrace.join "\n\t"}" if
-    Gem.configuration.backtrace
+    ui.errs.puts "\t#{ex.backtrace.join("\n\t")}" if Gem.configuration.backtrace
     ui.errs.puts "(continuing with the rest of the installation)"
   ensure
     Dir.chdir(old_pwd)
   end
 
-  undef setup_rdoc # redefining
   def setup_rdoc
     if File.exist?(@doc_dir) && !File.writable?(@doc_dir) then
       raise Gem::FilePermissionError.new(@doc_dir)
@@ -75,21 +72,21 @@ def install_yardoc
     run_yardoc '-o', rdoc_dir
   end
 
-  def install_ri_yard
-    @@install_ri_yard_orig.bind(self).call if @spec.has_rdoc?
-  end
-  @@install_ri_yard_orig = instance_method(:install_ri)
-  undef install_ri # redefining
-  alias install_ri install_ri_yard
-
-  def install_rdoc_yard
-    if @spec.has_rdoc?
-      @@install_rdoc_yard_orig.bind(self).call
-    elsif @spec.has_yardoc?
-      install_yardoc
+  unless instance_methods.include?(:install_ri_yard)
+    def install_ri_yard
+      install_ri_yard_orig if @spec.has_rdoc?
+    end
+    alias install_ri_yard_orig install_ri
+    alias install_ri install_ri_yard
+
+    def install_rdoc_yard
+      if @spec.has_rdoc?
+        install_rdoc_yard_orig
+      elsif @spec.has_yardoc?
+        install_yardoc
+      end
     end
+    alias install_rdoc_yard_orig install_rdoc
+    alias install_rdoc install_rdoc_yard
   end
-  @@install_rdoc_yard_orig = instance_method(:install_rdoc)
-  undef install_rdoc # redefining
-  alias install_rdoc install_rdoc_yard
 end