Interpret max_line_length=off as printWidth: Number.POSITIVE_INFINITY

[josephfrazier]

This fixes #7, see prettier/prettier#14514 for more context:

TL;DR: Should max_line_length=off in .editorconfig get interpreted as printWidth: Number.MAX_SAFE_INTEGER, or should we continue ignoring it, or something else?

Hey everyone, I'm the maintainer of editorconfig-to-prettier, which Prettier uses to convert EditorConfig configuration to Prettier configuration.

Over 5 years ago, bug #3410 was reported regarding the handling of max_line_length=off, and resulted in @duailibe fixing editorconfig-to-prettier to ignore max_line_length=off in .editorconfig files (the corresponding dependency version bump can be found here).

However, there's been some renewed interest from @celluj34 in having Prettier interpret max_line_length=off to mean e.g. printWidth: A_REALLY_BIG_NUMBER like Number.MAX_SAFE_INTEGER.

My question is, would this cause unintended consequences? For example, would Prettier attempt to generate very long lines for files where max_line_length=off? I see that https://prettier.io/docs/en/options.html#print-width says:

In other words, don’t try to use printWidth as if it was ESLint’s max-len – they’re not the same. max-len just says what the maximum allowed line length is, but not what the generally preferred length is – which is what printWidth specifies.

but I wonder if it would be ok in practice. I took a quick look at the playground with --print-width set to 9999, and the output seems reasonable-ish:

function HelloWorld({ greeting = "hello", greeted = '"World"', silent = false, onMouseOver }) {
  if (!greeting) {
    return null;
  }

  // TODO: Don't use random in render
  let num = Math.floor(Math.random() * 1e7)
    .toString()
    .replace(/\.\d+/gi, "");

  return (
    <div className="HelloWorld" title={`You are visitor number ${num}`} onMouseOver={onMouseOver}>
      <strong>{greeting.slice(0, 1).toUpperCase() + greeting.slice(1).toLowerCase()}</strong>
      {greeting.endsWith(",") ? " " : <span style={{ color: "grey" }}>", "</span>}
      <em>{greeted}</em>
      {silent ? "." : "!"}
    </div>
  );
}

Part of me thinks that if someone is explicitly putting max_line_length=off in their .editorconfig, then they should be ok with this formatting. On the other hand, I haven't really used Prettier for a while now, and I'm not very familiar with the variety of use cases people have for it, so I thought I'd ask here.

What do you think? Should max_line_length=off in .editorconfig get interpreted as printWidth: Number.MAX_SAFE_INTEGER, or should we continue ignoring it, or something else?

Thanks!

It make sense to support it. Let's parse it as Infinity.

https://github.com/prettier/prettier/blob/5446a8f32a2717762c4d7a1bd5fe2615d76ebec7/src/language-js/print/template-literal.js#L55

Oh, thanks for pointing that out, we're already using a "really big number" in a handful of places.

I'll probably wait on some other maintainers to chime in before making any changes in my package, but I appreciate the feedback 👍🏻

I think we can also improve the doc printer by skipping this check if printWidth is Infinity.

https://github.com/prettier/prettier/blob/5446a8f32a2717762c4d7a1bd5fe2615d76ebec7/src/document/doc-printer.js#L162

I'll probably wait on some other maintainers to chime in before making any changes in my package, but I appreciate the feedback 👍🏻

Oh lol, I see now that you're the primary contributor nowadays (this year so far)

I'd be happy to publish a new version of editorconfig-to-prettier that converts max_line_length=off to printWidth: Number.POSITIVE_INFINITY, but I'm not sure if I can help out with the adding tests/optimizations here in the Prettier repo (but I might try!). How does that sound?