Thanks for contributing @outofambit!

This is a breaking change and should have been in a major version. We rely on --list-different to check files are formatted in CI and break the build if they are not. There is no mention in the changelog of what different flags need to be provided to maintain this behaviour. I noticed this because files would constantly get reformatted despite us checking in CI with --list-different.

There actually doesn't even seem to be any way to achieve this now because --check is not released yet

If you don’t pass --write, Prettier will still exit with 1.

Yey. I have more than 25 repositories with an npm script that does both --write and --list-different and is used in CI.

Why are you using both in CI?

Because I defined an npm script called prettier that can be used both in CI and locally, to have a single point where the file pattern is defined.

See https://sourcegraph.com/search?q=r:%5Egithub.com/sourcegraph/+%22prettier%5C%22:+%5C%22prettier%22+f:package.json

You could set it up with just --list-different and have a format script that runs yarn prettier --write.

Yes, but I would have to define the glob twice, or have one script call into the other. I'm not saying it's not possible, I'm just saying this requires me to update all these repositories and is therefor clearly a breaking change that should not have been introduced in a patch release (and reverted, tbh).

cc @prettier/core

@felixfbecker there was some discussion of this in #4144. I believe we determined this to be a bug, so fixing it would not constitute a breaking change.

The workaround I am using now is

    "prettier": "prettier --list-different --write \"**/{*.{js?(on),ts,md,yml},.*.yml}\"",
    "prettier-check": "npm run prettier -- --write=false",