JSON.pretty_generate generates different output to MRI for at least an empty hash

[chrisseaton]

require 'json'
puts JSON.pretty_generate({})

% chruby 2.6.5
% ruby -v test.rb
ruby 2.6.5p114 (2019-10-01 revision 67812) [x86_64-darwin19]
{
}
% chruby truffleruby-20.1.0
% ruby -v test.rb
truffleruby 20.1.0, like ruby 2.6.5, GraalVM CE Native [x86_64-darwin]
{

}

So does JRuby jruby/jruby#6338

[eregon]

It's an issue of json/pure, it also happens on MRI:

$ ruby -v -e 'require "json/pure"; puts JSON.pretty_generate({})'
ruby 2.6.6p146 (2020-03-31 revision 67876) [x86_64-linux]
{

}

Could you file an issue or make a PR to https://github.com/flori/json ?

[chrisseaton]

Fixed by ruby/json#449.

[chrisseaton]

That's merged now. I'll close on anticipation you'll pick up the new version soon enough.

[eregon]

I'll watch (= enable notifications for) the json repo for releases.
We should probably use the json version that MRI uses for the stdlib though.
So if this fix is important, we could manually cherry-pick it on top of the stdlib version.
Do you think that's worth it? Are some tests failing without it?

We might also consider switching to the C extension for maximum compatibility, the main question there is what's the impact on performance.

[chrisseaton]

It caused a spec to fail in practice.

But it's not actually a problem - minor workaround to allow for it. I wouldn't cherry-pick it.