Support Haml 6

[jkowens]

Use Haml::Buffer only if it is defined. Resolves #1816.

[jkowens]

@k0kubun I appreciate your help 🙏

I'm seeing this warning when trying to upgrade to haml 6:

Haml::TempleEngine: Option :line is invalid
/opt/hostedtoolcache/Ruby/2.6.10/x64/lib/ruby/gems/2.6.0/gems/temple-0.8.2/lib/temple/mixins/options.rb:22: warning: instance variable @option_validator_disabled not initialized

I'm also seeing our specs fail with this result:

  5) Sinatra::ContentFor Haml with content_for in Ruby passes values to the blocks
     Failure/Error: expect(render(inner, :passes_values)).to eq("<i>1</i>2")

       expected: "<i>1</i>2"
            got: "&lt;i&gt;1&lt;/i&gt;2"

It looks like Haml is escaping the output. Can we mark it safe somehow?

[k0kubun]

I'm seeing this warning when trying to upgrade to haml 6:

rtomayko/tilt#387 seems to address it. We'd need to get it merged.

It looks like Haml is escaping the output. Can we mark it safe somehow?

You could pass escape_html: false to the engine, or use != instead of = to embed a script without escaping it.

[jkowens]

You could pass escape_html: false to the engine, or use != instead of = to embed a script without escaping it.

Of course! I see we do use != that for hamlit, sorry to even bother you about that 🤦‍♂️ Thank you!

[froderik]

So it seems that haml 6 is not supported out of the box. I needed to explicitly configure haml to not escape html like this:

set :haml escape_html: false

in order to get yielded haml inside a layout to not be escaped. Adding it here if anyone else stumbles upon the same problem.

[dentarg]

or you can use != haml ... / != yield where needed instead of allowing unescaped HTML all the time