Add option to enforce certain line endings

[kachkaev]

This PR contains a minimal viable implementation of #5320.

There is also a sidecar PR in another repo to read .editorconfig option as suggested by @evilebottnawi. I believe it is ready to be reviewed and can be merged after we close the first item in the TODO list below. We need to release a new version of editorconfig-to-prettier before completing this feature.

• I’ve added tests to confirm my change works.
• (If changing the API or CLI) I’ve documented the changes I’ve made (in the docs/ directory)
• I’ve read the contributing guidelines.

TODO (based on reviews)

• Agree on the option name:

  • eol (originally proposed) – a commonly known abbreviation, but may be confusing for newcomers
  • ✅ endOfLine / --end-of-line (suggested by two maintainers) – easier for newcomers, but takes longer to write; similar to .editorconfig's end_of_line
  • lineEnding(s?) / --line-ending(s?) – a commonly used term in human-to-human communication

• Decide if we want to support --endOfLine=cr at all. I'm not sure if Prettier can successfully parse files without LF at the moment. In any case, only CRLF and LF are prevalent (I haven’t seen anyone using CR only). Discussion: 4th conversation in Add option to enforce certain line endings #5327 (review) (marked as resolved by @ikatyang). Solution: keep cr amongst values for consistency with what .editorconfig supports.

• Merge [WIP] Convert .editorconfig’s end_of_line option to Prettier’s eol option josephfrazier/editorconfig-to-prettier#4 and replace a temporary used fork with the original package.

Looking forward for your thoughts folks 🙌

Future work

• Discuss if it's possible to apply an explicitly defined eol for files that have a syntax error don't have a known grammar (e.g. .gitignore). This should make it possible to prettier --write '**/*' or prettier-check '**/*'. We can do this in follow-up issues and PRs.

[lipis]

So this is ready to be merged? Maybe we should update the TODO list then..

[lipis]

Also if this is part of the 1.15 milestone we will have to update the blog post as well!

[kachkaev]

@lipis the PR is RFC (Ready for comments). I'm waiting for feedback from folks participating in #5320 to update TODOs. To be honest, I'd love --eol to become a part of 1.15, because consistently dealing with EOLs is a big pain for my team 🙏

[kachkaev]

Looks like the only thing left to do is to wait for the new version of editorconfig-to-prettier following the merge of josephfrazier/editorconfig-to-prettier#4! 🚀

[josephfrazier]

Looks like the only thing left to do is to wait for the new version of editorconfig-to-prettier following the merge of josephfrazier/editorconfig-to-prettier#4! 🚀

Done, you can upgrade to version 0.1.0 now!

[kachkaev]

Many thanks for doing this so quickly @josephfrazier! 💯

This PR should be ready for a final review and can be merged after that! @lipis can we squeeze it into 1.15 given that all is done? 😅

[duailibe]

@ikatyang You're pretty much managing the 1.15 release, I think you can decide to include in this release or not.

[ikatyang]

I'd like to wait for a day to see if there's any objection, it will be included in 1.15 if everything goes well.

[kachkaev]

After some more thinking, I changed the order of option values both in docs and cli (auto|cr|crlf|lf → auto|lf|crlf|cr). It used to be alphabetic and now the values go in the order of prevalence. See a resolved conversation in @lydell's review for details.

@ikatyang if you don't agree with this change, simply chop off my last commit before merging. Let me know if you need help with anything else!

[kachkaev]

Any final comments or suggestions folks? If not, shall we...

? 😅

[ikatyang]

Don't worry, I'll merge it later. I was fixing regressions.

[ikatyang]

Thanks!

[kachkaev]

Amazing!!! Many thanks for all your prompt comments and very useful reviews! I'm soooooo glad we could squeeze this feature into 1.15 that I'm jumping through the roof! 😅