Interaction between add-missing and i18n gem reserved keys check?

[mjankowski]

As part of a larger CI process, we are running the command: bundle exec i18n-tasks add-missing -l en

In a PR which bumped the version of i18n gem from 1.14.1 to 1.14.4, we see this failure: https://github.com/mastodon/mastodon/actions/runs/8187366599/job/22387716072?pr=29495

Relevant error portion:

bundler: failed to load command: i18n-tasks (/home/runner/work/mastodon/mastodon/vendor/bundle/ruby/3.2.0/bin/i18n-tasks)
/home/runner/work/mastodon/mastodon/vendor/bundle/ruby/3.2.0/gems/i18n-1.14.4/lib/i18n/backend/base.rb:65:in `translate': reserved key :default used in "Value. Interpolates: %{value}, %{human_key}, %{key}, %{default}, %{value_or_human_key}, %{value_or_default_or_human_key}" (I18n::ReservedInterpolationKey)

          raise ReservedInterpolationKey.new($1.to_sym, entry)

I think that the reserved keys check (added in i18n 1.14.3) is raising an error because of one of these reserved keywords being used in an interpolation - https://github.com/ruby-i18n/i18n/blob/master/lib/i18n.rb#L19-L34

The error seems to point back to this section of the i18n-tasks default config - https://github.com/glebm/i18n-tasks/blob/main/config/locales/en.yml#L32-L34 - and the %{default} key in particular being used there.

[glebm]

Oh, we should probably escape these "interpolations". They're meant to be there verbatim.

We'll also need to adjust the regex here to not match escaped interpolations:

i18n-tasks/lib/i18n/tasks/interpolations.rb

Line 8 in 56f378a

@variable_regex = /%{[^}]+}/.freeze

Interpolations can be escaped with %% (e.g. %%{default}) according to https://github.com/ruby-i18n/i18n/blob/master/lib/i18n/interpolate/ruby.rb

The regexp that we want for that is probably something like this: /(?<!%)%{[^}]+}/: https://rubular.com/r/catthAgMPZ1afN