New: Do not exclude dot files by default

[mightyiam]

Summary

ESLint excludes dot files (files whose names begin with .) by default.
This is a proposal to remove this default exclusion.

[jsf-clabot]

All committers have signed the CLA.

[rwjblue]

Another example here: In Ember applications we actually ended up adding !.* to the default .eslintignore due to folks accidentally assuming they were already checked.

ember-cli/ember-cli#8070

More info / background also in eslint/eslint#10341

[kaicataldo]

In theory, I support linting dotfiles and dotfolders by default. I agree that it is unexpected that .*.js files are ignored by default. Having dotfiles linted by default would also mean that the end user would be notified immediately if they are linting things they don't intend to (because they would warn), rather than silently ignoring files they believe are being linted.

All that being said, this could cause a lot of pain in the ecosystem, and I'm wary of making a change that could have such a huge ripple effect. One possible solution to this would be to change the default ignore patterns only when using eslint.config.js, since that's an opt-in path and won't break existing CI builds. I don't want to tie that RFC to this change, though, since it's been in the works so long and it sounds like we're finally reaching consensus on the feature set.

[mightyiam]

@kaicataldo is there test infrastructure to see some example breaking changes, please?

[kaicataldo]

@mightyiam Can you clarify what you mean?

[mightyiam]

A test that clones many projects that use ESLint, upgrades the version of ESLint and attempts to run their lint command to obtain examples of actual ecosystem breakage.

[kaicataldo]

We don't have infrastructure to do this. I'm also not sure it's necessary, given how clear of a breaking change this is.

Note that this change isn't limited to configuration dotfiles. As a concrete example, many popular tools create caches (Gatsby creates a .cache directory filled with *.js files, for instance) that are currently ignored by default. This change would mean the contents would suddenly be linted if the file isn't included in the project's .eslintignore.

[kaicataldo]

And to be clear, doing a test like the above wouldn't necessarily give us the data we need. The needs and setups of open source projects versus closed source applications can be very different.

[nzakas]

I agree with the premise here — less magic is better. I also agree that it’s a major breaking change and like @kaicataldo’s suggestion about waiting to make such a change until it can be shipped with the new config system. Since the ignore mechanism is tied in and will be changing anyway, that would be the best opportunity to incorporate a change like this.

[mightyiam]

@nzakas so this PR would be merged into #9? Are you taking that on? I wouldn't like to get into the details of #9 myself.

[nzakas]

Yes, I can work this into #9 so we have a holistic view of the changes.

[nzakas]

I've incorporated this into #7, so closing.