Warnings doing gem rdoc railties --ri - ruby-on-rails-3

Question

I have Rails 3.2.8 installed and what gem update --system says is the latest ruby gems, running ruby 1.9.3-p194 on a Mac.
When I do
gem rdoc railties --ri --overwrite
I get a plethora of warnings. (The --overwrite makes no difference). I've found various people complaining but no solutions.
Passing the errors through sort -u, the unique lines are:
Gem::SourceIndex#add_spec called from /usr/local/prvm/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/source_index.rb:127.
Gem::SourceIndex#initialize called from /usr/local/prvm/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/source_index.rb:67.
Gem::SourceIndex#load_gems_in called from /usr/local/prvm/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/source_index.rb:322.
Gem::SourceIndex#refresh! called from /usr/local/prvm/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/source_index.rb:95.
Gem::SourceIndex#search called from /usr/local/prvm/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/commands/rdoc_command.rb:64.
Gem::SourceIndex#spec_dirs= called from /usr/local/prvm/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/source_index.rb:94.
Gem::SourceIndex.from_gems_in called from /usr/local/prvm/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/source_index.rb:47.
Gem::SourceIndex.from_installed_gems called from /usr/local/prvm/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/commands/rdoc_command.rb:64.
Gem::SourceIndex.installed_spec_directories called from /usr/local/prvm/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/source_index.rb:47.
NOTE: Gem::SourceIndex#add_spec is deprecated, use Specification.add_spec. It will be removed on or after 2011-11-01.
NOTE: Gem::SourceIndex#initialize is deprecated with no replacement. It will be removed on or after 2011-11-01.
NOTE: Gem::SourceIndex#load_gems_in is deprecated with no replacement. It will be removed on or after 2011-11-01.
NOTE: Gem::SourceIndex#refresh! is deprecated with no replacement. It will be removed on or after 2011-11-01.
NOTE: Gem::SourceIndex#search is deprecated with no replacement. It will be removed on or after 2011-11-01.
NOTE: Gem::SourceIndex#spec_dirs= is deprecated, use Specification.dirs=. It will be removed on or after 2011-11-01.
NOTE: Gem::SourceIndex.from_gems_in is deprecated with no replacement. It will be removed on or after 2011-10-01.
NOTE: Gem::SourceIndex.from_installed_gems is deprecated with no replacement. It will be removed on or after 2011-10-01.
NOTE: Gem::SourceIndex.installed_spec_directories is deprecated, use Specification.dirs. It will be removed on or after 2011-11-01.
Here is my list of gems:
*** LOCAL GEMS ***
actionmailer (3.2.8)
actionpack (3.2.8)
activemodel (3.2.8)
activerecord (3.2.8)
activerecord_constraints (0.1.1)
activeresource (3.2.8)
activesupport (3.2.8)
arel (3.0.2)
bigdecimal (1.1.0)
builder (3.0.3)
bundler (1.1.3)
capistrano (2.13.3)
coffee-rails (3.2.2)
coffee-script (2.2.0)
coffee-script-source (1.3.3)
daemons (1.1.8)
dalli (2.2.1)
erubis (2.7.0)
eventmachine (0.12.10)
execjs (1.4.0)
highline (1.6.14)
hike (1.2.1)
i18n (0.6.1)
io-console (0.3)
journey (1.0.4)
jquery-rails (2.1.2)
jquery-ui-rails (2.0.0)
jruby-pageant (1.0.2)
json (1.7.5)
mail (2.4.4)
mime-types (1.19)
minitest (2.5.1)
multi_json (1.3.6)
net-scp (1.0.4)
net-sftp (2.0.5)
net-ssh (2.5.2)
net-ssh-gateway (1.1.0)
pg (0.14.1)
polyglot (0.3.3)
rack (1.4.1)
rack-cache (1.2)
rack-ssl (1.3.2)
rack-test (0.6.1)
rails (3.2.8)
rails-footnotes (3.7.8)
railties (3.2.8)
rake (0.9.2.2)
rdoc (3.12)
rubygems-update (1.8.24)
sass (3.1.19)
sass-rails (3.2.5)
sprockets (2.1.3)
sqlite3 (1.3.6)
thin (1.4.1)
thor (0.16.0)
tilt (1.3.3)
treetop (1.4.10)
tzinfo (0.3.33)
uglifier (1.2.5)
The "ick" is "ri Rails::Engine" produces no output when in fact it has tons of really beautiful documentation. I bumped into this often on my Mac and would like to get a full set of docs working on my Mac.
What is probably a separate issue the command
gem rdoc bigdecimal --ri
produces the same warnings but ends with:
ERROR: While executing gem ... (Errno::ENOENT)
No such file or directory - /usr/local/prvm/ruby-1.9.3-p194/lib/ruby/gems/1.9.1/gems/bigdecimal-1.1.0
Is this an issue with railties or with rubygems or my local set up?
Any way to get around it?

Answer 1

If there were an error RubyGems would explicitly say so and exit with a non-zero error code. For the first case, as you note, you see only warnings.
These warnings have been fixed in the RubyGems but it is not easy to back port the fix to RubyGems 1.8.
For the second case, we aim to solve this with the "default gems" feature in Ruby 2.0. The bigdecimal documentation ships as part of ruby so there is no need to regenerate it.

Answer 2

The question was very badly phrased. I incorrectly associated the warnings with the fact that "gem rdoc railties" did not produce the internal documentation. I finally tracked down that particular question. For some reason, the gem spec excludes all files. Just remove that line and you get good documentation.
diff -c /tmp/railties-3.2.8.gemspec ./railties-3.2.8.gemspec
*** /tmp/railties-3.2.8.gemspec 2012-09-19 08:40:57.000000000 -0500
--- ./railties-3.2.8.gemspec 2012-09-19 08:39:32.000000000 -0500
***************
*** 12,18 ****
s.executables = ["rails"]
s.files = ["bin/rails"]
s.homepage = "http://www.rubyonrails.org"
! s.rdoc_options = ["--exclude", "."]
s.require_paths = ["lib"]
s.required_ruby_version = Gem::Requirement.new(">= 1.8.7")
s.rubygems_version = "1.8.24"
--- 12,18 ----
s.executables = ["rails"]
s.files = ["bin/rails"]
s.homepage = "http://www.rubyonrails.org"
! # s.rdoc_options = ["--exclude", "."]
s.require_paths = ["lib"]
s.required_ruby_version = Gem::Requirement.new(">= 1.8.7")
s.rubygems_version = "1.8.24"