Exceptions raised from templates should show template code not compiled methods

[dhh]

Seems like we've regressed on exceptions raised from within ERB templates. They're showing the backtrace of the compiled method instead of the underlying template. That's not very helpful.

[rafaelfranca]

I just tried to reproduce in a new Rails application using Rails on main and could not:

My Ruby version is ruby 3.2.2 (2023-03-30 revision e51014f9c0) [aarch64-linux].

What is your Ruby version?

[davidcsete]

I just tried to reproduce in a new Rails application using Rails on main and could not:

My Ruby version is `ruby 3.2.2 (2023-03-30 revision e51014f9c0) [aarch64-linux]`.

What is your Ruby version?

I could reproduce it on an apple silicone using ruby version 3.2.2

[rafaelfranca]

I just tried on apple silicon and linux the following steps:

rails new --dev my_app
cd my_app
bin/rails g scaffold posts title body
bin/rails db:migrate

Then I edited posts/index.html.erb to add the invalid code, started the server and got the error pointing to the template. I'm also using 3.2.2.

Which steps did you take to reproduce?

[dhh]

Oh this is a strange one. This triggers the busted exception:

<ul>
  <li><%= link_to post.title, post %></li>
</ul>

<%= link_to "New book", new_book_path %>

but this does not:

<ul>
  <li>
    <%= link_to post.title, post %>
  </li>
</ul>

<%= link_to "New book", new_book_path %>

[rafaelfranca]

aha! I think maybe the compiled template line isn't matching the source line.

[rafaelfranca]

Just confirmed this also happens on 7.1

[nikhilbhatt]

Minimum code to regenerate the issue -->

<li><%= link_to post.title, post %></li>

Even if empty spaces are present after closing braces it will result in showing compiled string.

<%= link_to post.title, post %>  <empty_spaces>

Problem

1. File- activesupport/lib/active_support/core_ext/erb/util.rb method - tokenize
2. In this tokenize method we are not handling end text that is present after the code %>
3. Because of this if empty spaces or text is present after code %> it will result in raise NotImplementedError
4. And the final output will be the compiled code because this method will return nil.

Solution

1. Handle the edge case if some text is present at the end in string.

  unless source.eos? || source.exist?(/#{start_re}|#{finish_re}/m)
     tokens << [:TEXT, source.rest]
     source.terminate
  end