How do I enable the Ruby 2.3 `--enable-frozen-string-literal` globally in Rails?

Question

I am building a greenfield Rails application on top of Ruby 2.3, and I would like all Rails commands (e.g. rails s, rails c) and all Ruby commands (e.g. rake do:something) to use the new immutable-String functionality introduced in Ruby 2.3. (See, e.g. https://wyeworks.com/blog/2015/12/1/immutable-strings-in-ruby-2-dot-3/)

So, how do I pass that lovely --enable-frozen-string-literal Ruby option down to Ruby in all possible contexts where some command I issue bottoms out in Ruby?

Thanks in advance!

Broyles

Answer 1

As far as I know, best way to do it is setting environment variable like followings:

export RUBYOPT=--enable-frozen-string-literal

or

setenv RUBYOPT --enable-frozen-string-literal

However, don't try it right now. It simply doesn't work because some codes in Bundler gem are attempting to modify frozen String. Wait until they fix the problem.

Manvel

Bundler should be able to support frozen string literals since v1.12. If it still doesn't work, file an issue like this. – Scaleboard

More portable: RUBYOPT=--enable-frozen-string-literal; export RUBYOPT will work with /bin/sh on FreeBSD, bash, zsh, fish, etc. – Napoleon

what about if gems are trying to modify strings? It's probably not common but I'm sure it happens somewheere. – Coronal

Definitely not ready for production :) There was an error while trying to load the gem 'haml'. (Bundler::GemRequireError) Gem Load Error is: can't modify frozen String – Puseyism

Not even Rails v5.0.2 handles it: a rather fresh app errors with …actionview-5.0.2/lib/action_view/helpers/javascript_helper.rb:16:in 'force_encoding': can't modify frozen String (RuntimeError) on startup. – Brasilein

rails 5.2 fails for me too :/ – Mazurek