Support frozen strings with REXML

[frederikspang]

Tests are passing with export RUBYOPT=--enable-frozen-string-literal

[johnnyshields]

@frederikspang I am pretty sure this is fixed on v2 already, but @pitbulk it might make sense to fix this on master anyway as it will is needed for Ruby 3.4

[frederikspang]

@johnnyshields I've adjusted some stuff from review. UUID_PREFIX is used as a constant, and .replace with Utils.set_prefix, which is not working out great :). I've replaced it with a variable. Should we deprecate or remove the (now unused) constant?

[johnnyshields]

@frederikspang yikes wow we were calling replace on a constant 🤦‍♂️ . The way you have it now with @@prefix is fine.

[pitbulk]

Changes are not compatible with ruby 2.X versions.

@johnnyshields, for this, the v2 should be used instead. we should address the UUID_PREFIX on that brach.

[johnnyshields]

@pitbulk frozen string stuff is handled already on 2.x. This is a "backport" in case we want it on 1.x branch, but the alternative here would be to just close this PR and tell users they must use 2.x for Ruby 3.4+. Which is reasonable in my opinion.

[johnnyshields]

Mutable constant addressed here: #735

[frederikspang]

@johnnyshields Frozen strings is not exclusive for Ruby 3.4 - It's just moving towards default frozen, with "chilled string".

I think that not supporting frozen strings for < 3.4 would be a mistake, when the backport is somewhat simple for 1.x branch.

[frederikspang]

Specs may have been solved for older ruby versions, with using .dup instead of +"" for unfreezing. Could you rerun specs?

[johnnyshields]

It's @pitbulk 's call whether he wants to release for 1.x branch.

[johnnyshields]

I don't think I can run the tests--@pitbulk can you activate?

[pitbulk]

@frederikspang, it seems for ruby >= 3.4.0 we need to add mutex_m gem on the gemspec, can you add it?

/opt/hostedtoolcache/Ruby/3.4.1/x64/lib/ruby/gems/3.4.0/gems/minitest-5.18.1/lib/minitest.rb:3: warning: mutex_m was loaded from the standard library, but is not part of the default gems starting from Ruby 3.4.0.
You can add mutex_m to your Gemfile or gemspec to silence this warning.
Stopped processing SimpleCov as a previous error not related to SimpleCov has been detected
/opt/hostedtoolcache/Ruby/3.4.1/x[6](https://github.com/SAML-Toolkits/ruby-saml/actions/runs/12715610842/job/35546871648?pr=728#step:5:7)4/lib/ruby/3.4.0/bundled_gems.rb:82:in 'Kernel.require': cannot load such file -- mutex_m (LoadError)

[frederikspang]

@pitbulk Got it :)