gettext: error about execution flow in exception handling in ruby >=3.3

[henk84]

Bug reported on IRC, nickname of the reporter replaced with 'placeholder' because I’m not sure whether they want to be associated. Content of their pastebin is the codeblock below the quote from the IRC conversation, similarly pseudonymized:

07:55 https://dpaste.com/PLACEHOLDER_ID was my ruby3.3 patch, though of course I don't know if it's right.
08:32 oh, that’s not much … what’s the problem without that patch?
08:34 hrm, does it fail and then loop failing?
08:45 Mar 13 03:45:06 Loki rbot[569443]: internal:/usr/lib/ruby/vendor_ruby/rubygems/core_ext/kernel_require.rb:136:in require': 08:45 <placeholder> Mar 13 03:45:06 Loki rbot[569443]: /usr/lib/ruby/vendor_ruby/rbot/load-gettext.rb:71: Invalid retry after ensure (SyntaxError) 08:45 <placeholder> Mar 13 03:45:06 Loki rbot[569443]: retry 08:45 <placeholder> Mar 13 03:45:06 Loki rbot[569443]: ^~~~~ 08:45 <placeholder> Mar 13 03:45:06 Loki rbot[569443]: from <internal:/usr/lib/ruby/vendor_ruby/rubygems/core_ext/kernel_require.rb>:136:in require'
08:45 Mar 13 03:45:06 Loki rbot[569443]: from /usr/lib/ruby/vendor_ruby/rbot/ircbot.rb:33:in <top (required)>' 08:45 <placeholder> Mar 13 03:45:06 Loki rbot[569443]: from <internal:/usr/lib/ruby/vendor_ruby/rubygems/core_ext/kernel_require.rb>:136:in require'
08:45 Mar 13 03:45:06 Loki rbot[569443]: from internal:/usr/lib/ruby/vendor_ruby/rubygems/core_ext/kernel_require.rb:136:in require' 08:45 <placeholder> Mar 13 03:45:06 Loki rbot[569443]: from /usr/bin/rbot:90:in

'
08:53 henk: ↑ that's the error that happens.
09:49 errrr, wtf? there is no "ensure" in my code o_O
09:58 I get not a single search result for "Invalid retry after ensure"
09:58 on duckduckgo
10:10 lib/rbot/load-gettext.rb
10:10 133: ensure
10:12 yeah, that’s not in context. unless there is some chain of calls involved that I haven’t traced yet.
10:18 Only one I found in there. Like I said I don't really know the correct fix, but removing the retry at least gets me online.

Description: Fix launching with Ruby 3.3
Author: placeholder <placeholder@example.com>
Origin: vendor
Forwarded: no

---
 lib/rbot/load-gettext.rb |    1 -
 1 file changed, 1 deletion(-)

--- a/lib/rbot/load-gettext.rb
+++ b/lib/rbot/load-gettext.rb
@@ -68,7 +68,6 @@ begin
         result
       end
     end
-    retry
   end
 
   module GetText

The relevant code is

rbot/lib/rbot/load-gettext.rb

Lines 53 to 72 in 6d3eb99

	begin
	bindtextdomain 'rbot'
	rescue NoMethodError => e
	error e
	warning 'Trying to work around RubyGems/GetText incompatibility'
	module ::Gem
	def self.all_load_paths
	result = []
	Gem.path.each do |gemdir|
	each_load_path all_partials(gemdir) do |load_path|
	result << load_path
	end
	end
	result
	end
	end
	retry
	end

and I don’t understand why it’s there, yet.
It’s also not really clear what the error means. There is no (obvious) call to ensure but maybe this piece of code is called in some ensure block in a file far, far away from where the error occurs.

If anyone wants to dig into that or knows what the error is about, that would be great!

In any case just retrying without end seems stupid, so getting rid of that retry call seems like a good idea in any case. Retrying X times, e.g. by introducing a retry counter, does not seem to make sense as the problem is likely permanent.

[Oblomov]

This is one of the issues solved in my master branch

Oblomov/rbot@5b408c6

[henk84]

With help from #ruby@libera I found out that this is a bug in ruby 3.3 which has been fixed in 3.4 and newer:
https://bugs.ruby-lang.org/projects/ruby-master/repository/git/revisions/eaa0fbf9b956fa25e73c3d55e2eba8887324e233/diff

They also were very kind to provide code that reproduces the issue:

begin
  print "begin: 1", "\n"
  begin
    printx "begin: 2", "\n"
  rescue => ex
    module Foo
      def printx(...)
        print(...)
      end
    end
    extend Foo
    retry
  end
end

The following code causes a similar error but not quite the same. Also, it causes the error in ruby 3.1.2p20 (current debian stable bookworm), not just in 3.3:

begin
  print "begin: 1", "\n"
  begin
    print "begin: 2", "\n"
    raise
  rescue => ex
  end
  retry
end

Since this is caused by a bug in ruby, I’m reluctant to change (let alone just remove) that exception handling code without really understanding what it does and why it was introduced. Sadly the git history doesn’t really explain it and I didn’t have the chance yet to dig into that code. I also have no idea how gettext works or what it’s used for, so this would take some deeper digging for me to get there.