How can I tell I really turned on a pandoc extension?

[jidanni]

Description

$ quarto render yy.qmd --to html
$ quarto render yy.qmd --to html+east_asian_line_breaks
$ quarto render yy.qmd --to html+east_asian_line_breaksxxx
$ quarto render yy.qmd --to html+groovy_asian_line_breaks

all behave the same.

My first step in debugging is to tell if Pandoc actually accepted the
+stuff. And why is there no error message no matter what crazy argument
I add? Maybe quarto didn't pass it to Pandoc?

Wait, #8520

But still, the user has no way to tell if the plus stuff got sent to Pandoc in the first place.

[mcanouil]

Have you considered checking the log output?

pandoc 
  to: html+east_asian_line_breaks
  output-file: issue-14440.html
  standalone: true
  section-divs: true
  html-math-method: mathjax
  wrap: none
  default-image-extension: png
  variables: {}
  
metadata
  document-css: false
  link-citations: true
  date-format: long
  lang: en
  
Output created: issue-14440.html

You can also check the output of the extension in plain Pandoc: quarto pandoc ...

[mcanouil]

See:

• Improve control over Pandoc reader extensions #8520 (comment)