RI/Rdoc 7.0.3 -- Marshal.load error when trying to load std/core library documentation using ri

[scriabin-enjoyer]

Hello, as a preface I am a bit out of my depth here, so I hope you can bare with me.

Problem

When I use the utility ri to view core and standard library documentation, either directly from the command-line, IRB, or from within a ruby file, I get a Marshal.load error, telling me that it can't unpack the RDoc::Markup::Heading class because it isn't a struct (more info below). This happens for all stdlib or core library names. Additionally, when using IRB, it seems that when IRB tries to fetch the documentation for various names/methods, it tries to load the documentation with rdoc and this is causing IRB to crash with the same error.

This problem seems specific to rdoc version 7.0.3. I have other (older) versions of ri/rdoc including 7.0.1, 6.17.0, 6.16.1, 6.16.0, 6.15.1 which all seem to work, and using the following command I am able to load documentation using ri without any problem:

ri _7.0.1_ Hash # This works fine and produces the rdoc info for the Hash class in my shell's default pager

Steps to reproduce the problem:

• run ri Hash at the command line (bash)
• run ri Hash from within IRB
• start IRB at the command-line, start typing Hash, tab down to highlight the "Hash" entry in the completion-suggestion dropdown, and wait for IRB to crash
• in a file, require rdoc/ri/driver and execute Rdoc::RI::Driver.new.display_name "Hash"

All of the above produce the following error:

<internal:marshal>:34:in 'Marshal.load': class RDoc::Markup::Heading not a struct (TypeError)

Diagnostic Info

Here is a ruby script to print my system info, as well as a snippet that reproduces the exact error I get in all cases mentioned above:

require 'rdoc'
require 'rdoc/ri/driver'

puts "Ruby version: #{RUBY_VERSION}"
puts "Ruby patchlevel: #{RUBY_PATCHLEVEL}"
puts "Ruby platform: #{RUBY_PLATFORM}"
puts "RDoc version: #{RDoc::VERSION}"
puts "RDoc file: #{RDoc.const_source_location :VERSION}"
puts "My RI paths:"
RDoc::RI::Paths.each { |path| puts "    #{path}" }

3.times { puts }

puts 'MY ERROR:'
begin
  RDoc::RI::Driver.new.display_name 'Hash'
rescue => e
  puts e.full_message
end

And here is the corresponding output (in a dropdown because its long):

Details

Ruby version: 3.4.6
Ruby patchlevel: 54
Ruby platform: x86_64-linux
RDoc version: 7.0.3
RDoc file: ["/home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/rdoc-7.0.3/lib/rdoc/version.rb", 8]
My RI paths:
    /home/scriabin/.rbenv/versions/3.4.6/share/ri/3.4.0/system
    /home/scriabin/.rbenv/versions/3.4.6/share/ri/3.4.0/site
    /home/scriabin/.local/share/rdoc
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/action_text-trix-2.1.15/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/actioncable-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/actionmailbox-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/actionmailer-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/actionpack-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/actiontext-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/actionview-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/activejob-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/activemodel-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/activerecord-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/activestorage-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/activesupport-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/ast-2.4.3/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/benchmark-ips-2.14.0/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/lint_roller-1.1.0/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/parallel-1.27.0/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/parser-3.3.10.0/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/rails-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/railties-8.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/rainbow-3.1.1/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/regexp_parser-2.11.3/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/rubocop-1.81.7/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/rubocop-ast-1.48.0/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/ruby-progressbar-1.13.0/ri
    /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/doc/rubygems-update-4.0.2/ri



MY ERROR:
<internal:marshal>:34:in 'Marshal.load': class RDoc::Markup::Heading not a struct (TypeError)
	from /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/rdoc-7.0.3/lib/rdoc/store.rb:982:in 'block in RDoc::Store#marshal_load'
	from /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/rdoc-7.0.3/lib/rdoc/store.rb:982:in 'IO.open'
	from /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/rdoc-7.0.3/lib/rdoc/store.rb:982:in 'RDoc::Store#marshal_load'
	from /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/rdoc-7.0.3/lib/rdoc/store.rb:627:in 'RDoc::Store#load_class_data'
	from /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/rdoc-7.0.3/lib/rdoc/store.rb:607:in 'RDoc::Store#load_class'
	from /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/rdoc-7.0.3/lib/rdoc/ri/driver.rb:731:in 'block in RDoc::RI::Driver#classes_and_includes_and_extends_for'
	from /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/rdoc-7.0.3/lib/rdoc/ri/driver.rb:729:in 'Array#map'
	from /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/rdoc-7.0.3/lib/rdoc/ri/driver.rb:729:in 'RDoc::RI::Driver#classes_and_includes_and_extends_for'
	from /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/rdoc-7.0.3/lib/rdoc/ri/driver.rb:824:in 'RDoc::RI::Driver#display_class'
	from /home/scriabin/.rbenv/versions/3.4.6/lib/ruby/gems/3.4.0/gems/rdoc-7.0.3/lib/rdoc/ri/driver.rb:858:in 'RDoc::RI::Driver#display_name'
	from rdoc_test.rb:16:in '<main>'

The error's differ slightly in the different situations, but the core problem seems to be from this call sequence:

RDoc::Store#load_class -> RDoc::Store#load_class_data -> RDoc::Store#marshal_load

Additional Info

I think this may be related: to #1389

Please let me know if there is any more information I can provide, or if there is already a fix available that I haven't been able to find.

[st0012]

Can you test if the same issue happen with Ruby 4.0 and RDoc version that's NOT 7.0.3?
I agree that it's related to #1389, and I think it's also related to the fact that RDoc was still a default gem before Ruby 4.0 (so it's ri data is generated along with Ruby itself).

[scriabin-enjoyer]

hi @st0012

just installed 4.0.0, and can confirm that this ruby version comes with rdoc 7.0.3, as this was the only version installed by default, and these work completely fine together.

Rdoc 7.0.1 (installed with gem install rdoc --version 7.0.1) DOES NOT work with ruby 4.0.0.
My ruby version:

$ ruby --version
ruby 4.0.0 (2025-12-25 revision 553f1675f3) +PRISM [x86_64-linux]

And using rdoc 7.0.1, I get the following error. It's not exactly the same as the one in my original issue post, but the location of the incompatibility is the same:

$ ri _7.0.1_ Hash
/home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/store.rb:982:in 'Marshal.load': dump format error (ArgumentError)

    File.open(file, 'rb') {|io| Marshal.load(io, MarshalFilter)}
                                             ^^^^^^^^^^^^^^^^^
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/store.rb:982:in 'block in RDoc::Store#marshal_load'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/store.rb:982:in 'IO.open'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/store.rb:982:in 'RDoc::Store#marshal_load'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/store.rb:627:in 'RDoc::Store#load_class_data'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/store.rb:607:in 'RDoc::Store#load_class'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/ri/driver.rb:731:in 'block in RDoc::RI::Driver#classes_and_includes_and_extends_for'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/ri/driver.rb:729:in 'Array#map'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/ri/driver.rb:729:in 'RDoc::RI::Driver#classes_and_includes_and_extends_for'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/ri/driver.rb:824:in 'RDoc::RI::Driver#display_class'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/ri/driver.rb:858:in 'RDoc::RI::Driver#display_name'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/ri/driver.rb:885:in 'block in RDoc::RI::Driver#display_names'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/ri/driver.rb:882:in 'Array#each'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/ri/driver.rb:882:in 'RDoc::RI::Driver#display_names'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/ri/driver.rb:1477:in 'RDoc::RI::Driver#run'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/lib/rdoc/ri/driver.rb:396:in 'RDoc::RI::Driver.run'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.1/exe/ri:12:in '<top (required)>'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/4.0.0/rubygems.rb:303:in 'Kernel#load'
	from /home/scriabin/.rbenv/versions/4.0.0/lib/ruby/4.0.0/rubygems.rb:303:in 'Gem.activate_and_load_bin_path'
	from /home/scriabin/.rbenv/versions/4.0.0/bin/ri:25:in '<main>'

Edit:
Sorry, I should have also tried 7.0.2. I just did, and I get the same error:

$ ri _7.0.2_ Hash
/home/scriabin/.rbenv/versions/4.0.0/lib/ruby/gems/4.0.0/gems/rdoc-7.0.2/lib/rdoc/store.rb:982:in 'Marshal.load': dump format error (ArgumentError)

    File.open(file, 'rb') {|io| Marshal.load(io, MarshalFilter)}

(the rest of the output is the same as above -- same stack trace but with 7.0.2)