Infinite loop when using mail 2.7.0 and 2.6.x. Works okay on 2.5.5 and below

[Nowaker]

This is happening to me on mail 2.7.0 and 2.6.x. Downgrading to 2.5.5 resolves the problem. I'd be happy to assist with finding the cause for this but I'd need a little guidance as to what to provide. Thanks.

  ... # and so on, repeat
  mail (2.7.0) lib/mail/message.rb:1831:in `encoded'
# end loop section
  mail (2.7.0) lib/mail/message.rb:1896:in `to_s'
  mail (2.7.0) lib/mail/fields/unstructured_field.rb:34:in `initialize'
  mail (2.7.0) lib/mail/field.rb:277:in `new'
  mail (2.7.0) lib/mail/field.rb:277:in `new_field'
  mail (2.7.0) lib/mail/field.rb:264:in `create_field'
  mail (2.7.0) lib/mail/field.rb:185:in `field'
  mail (2.7.0) lib/mail/field.rb:237:in `method_missing'
  mail (2.7.0) lib/mail/header.rb:213:in `block in encoded'
  mail (2.7.0) lib/mail/header.rb:212:in `each'
  mail (2.7.0) lib/mail/header.rb:212:in `encoded'
  mail (2.7.0) lib/mail/message.rb:1831:in `encoded'
# begin loop section
  actionmailer (4.2.10) lib/action_mailer/base.rb:562:in `set_payload_for_mail'
  actionmailer (4.2.10) lib/action_mailer/base.rb:542:in `block in deliver_mail'
  activesupport (4.2.10) lib/active_support/notifications.rb:164:in `block in instrument'
  activesupport (4.2.10) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
  activesupport (4.2.10) lib/active_support/notifications.rb:164:in `instrument'
  actionmailer (4.2.10) lib/action_mailer/base.rb:541:in `deliver_mail'
  mail (2.6.0) lib/mail/message.rb:232:in `deliver'
  actionmailer (4.2.10) lib/action_mailer/message_delivery.rb:85:in `deliver_now'
  actionmailer (4.2.10) lib/action_mailer/message_delivery.rb:105:in `deliver'
  app/models/message.rb:615:in `send_email'

[jeremy]

Could you check in a debugger to see why a message field is referencing the message itself?

[Nowaker]

OK, will do in the coming week. Thanks @jeremy.

[Nowaker]

I used a debugger and I couldn't really understand what was going on. Any tips where I should put breakpoints, and what to look at? The trace loop using the latest version of this library (2.7.1) is:

# ... and again: /home/nowaker/.rvm/gems/ruby-3.0.4/gems/mail-2.7.1/lib/mail/fields/unstructured_field.rb:34:in `initialize'
/home/nowaker/.rvm/gems/ruby-3.0.4/gems/mail-2.7.1/lib/mail/field.rb:279:in `new'
/home/nowaker/.rvm/gems/ruby-3.0.4/gems/mail-2.7.1/lib/mail/field.rb:279:in `new_field'
/home/nowaker/.rvm/gems/ruby-3.0.4/gems/mail-2.7.1/lib/mail/field.rb:266:in `create_field'
/home/nowaker/.rvm/gems/ruby-3.0.4/gems/mail-2.7.1/lib/mail/field.rb:187:in `field'
/home/nowaker/.rvm/gems/ruby-3.0.4/gems/mail-2.7.1/lib/mail/field.rb:239:in `method_missing'
/home/nowaker/.rvm/gems/ruby-3.0.4/gems/mail-2.7.1/lib/mail/header.rb:213:in `block in encoded'
/home/nowaker/.rvm/gems/ruby-3.0.4/gems/mail-2.7.1/lib/mail/header.rb:212:in `each'
/home/nowaker/.rvm/gems/ruby-3.0.4/gems/mail-2.7.1/lib/mail/header.rb:212:in `encoded'
/home/nowaker/.rvm/gems/ruby-3.0.4/gems/mail-2.7.1/lib/mail/message.rb:1831:in `encoded'
/home/nowaker/.rvm/gems/ruby-3.0.4/gems/mail-2.7.1/lib/mail/message.rb:1896:in `to_s'
/home/nowaker/.rvm/gems/ruby-3.0.4/gems/mail-2.7.1/lib/mail/fields/unstructured_field.rb:34:in `initialize'

[Nowaker]

I'm working on moving the application from Rails 4.x to 6.x and mail 2.7.1 is required... Hence I'm back to this :)

[Nowaker]

...Bumping to 2.8.0.rc1 fixes the problem.