Support --fix-dry-run for ESLint

[graingert]

(finished - exit code 1) ['/bin/zsh', '-c', '''/home/graingert/projects/redacted/frontend/node_modules/eslint/bin/eslint.js'' -c ''/home/graingert/projects/redacted/frontend/.eslintrc.json'' --fix ''/tmp/vGVEPLm/23/_btest.js''']

See eslint/eslint#9073

[graingert]

ah this looks like it's not possible, as the file cannot be sent via --fix

[w0rp]

Yeah. It doesn't do that because that doesn't work.

[graingert]

@w0rp updated title, can you reopen?

[w0rp]

Sure, I didn't know about that option. It looks like it was added just over a week ago.

We can add support for this with an option, which can be off by default, until enough time passes for people to upgrade.

[graingert]

Yeah I didn't spot it either

[w0rp]

--fix-dry-run is now supported where available, and --fix-to-stdout is support for eslint_d where available.

[w0rp]

Nope, I took it away again. The --fix-dry-run option is stupid because you can't just get the fixed file via stdout, you have to parse some JSON output. That means I'd need to add support for post-processing of output for fixers. That's worth supporting anyway.

[w0rp]

Okay, now ALE post-processes the JSON output to get the actual lines out of that, and --fix-dry-run is supported where available.