feat(typescript-estree): allow specifying project: true

[JoshuaKGoldberg]

PR Checklist

• Addresses an existing open issue: fixes Feature request: support looking up tsconfig.json relative to linted file #101
• That issue was marked as accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

Allows users to specify parserOptions.project: true to indicate each file should be linted with the closest tsconfig.json to that file.

• Initial draft working for "one-and-done" use case of
• Get it to also work for watch mode, where tsconfig.json files might be moved between lints
  • Work... ish. We won't know if someone moves a tsconfig.json to re-lint a currently visible file in an IDE. But as soon as the file is changed, we'll know to re-check its relative tsconfig.json anyway.
• Test it
• Document it

Throwing up a draft now to be very visible about progress. ✅

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• Node 14 - nx test parser --coverage=false
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• nx run-many --target=build --parallel --exclude website
• nx run-many --target=build --parallel --exclude website
• Node 18 - nx test ast-spec
• Node 18 - nx run-many --target=build --parallel --exclude website
• Node 18 - nx test type-utils
• Node 18 - nx run-many --target=build --parallel --exclude website
• Node 18 - nx test eslint-plugin
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• nx run-many --target=build --parallel --exclude website
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• Node 18 - nx test eslint-plugin-tslint
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• Node 18 - nx test parser
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• nx run-many --target=build --parallel --exclude website

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[typescript-eslint]

Thanks for the PR, @JoshuaKGoldberg!

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The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

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[bradzacher]

Get it to also work for watch mode, where tsconfig.json files might be moved between lints

if only we had a way to attach watchers to the disk 😿

[codecov]

Codecov Report

Merging #6084 (040a56a) into main (f330e06) will increase coverage by 0.00%.
The diff coverage is 94.28%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6084   +/-   ##
=======================================
  Coverage   91.52%   91.52%           
=======================================
  Files         371      372    +1     
  Lines       12651    12689   +38     
  Branches     3717     3730   +13     
=======================================
+ Hits        11579    11614   +35     
  Misses        754      754           
- Partials      318      321    +3     

Flag	Coverage Δ
unittest	91.52% <94.28%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...pt-estree/src/parseSettings/createParseSettings.ts	93.47% <66.66%> (-4.03%)	⬇️
...pescript-estree/src/parseSettings/ExpiringCache.ts	100.00% <100.00%> (+4.76%)	⬆️
...-estree/src/parseSettings/getProjectConfigFiles.ts	100.00% <100.00%> (ø)
...ipt-estree/src/parseSettings/resolveProjectList.ts	91.11% <0.00%> (-4.45%)	⬇️
...int-plugin/src/rules/strict-boolean-expressions.ts	98.90% <0.00%> (+0.06%)	⬆️

[bradzacher]

we're like 99% of the way there - just need to handle cache lifetime and we gucci

[JoshuaKGoldberg]

ugh git

[bradzacher]

Overall this LGTM - so stamped

Before you land it - could you do a perf test just so we can update the docs with messaging around perf if we need to?

To test the perf I'd just use the time tool against main then against your branch:

• git checkout main && yarn && time ./node_modules/.bin/eslint .
• git checkout parser-options-project-true && yarn && time ./node_modules/.bin/eslint .

You'll see a line like this:

./node_modules/.bin/eslint .  62.97s user 4.09s system 167% cpu 40.009 total

The first number is the one to compare.
I'd do a couple runs of each just to smooth any outlier slowness.

I'd expect this to be a little slower due to the lookup required for every file - but I think that with the caching you've built in it shouldn't be MUCH slower. For a big, deeply nested project they might find it has more of an impact.

If the difference is minuscule then I don't think we need to worry about any messaging, but if it's different enough one way or the other it's probably worth mentioning!

But this is why it'd be worth a test - just to see if it is actually different enough.

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If you wanted you could go hog-ham and investigate the proper perf trace before and after:
#6366 (comment)

The thing that would be interesting to see would be the cost of the createParseSettings before and after as that's where your changes are.
Would be interesting to see the proper breakdown!

[JoshuaKGoldberg]

• main: ./node_modules/.bin/eslint . 61.71s user 3.54s system 166% cpu 39.264 total
• parser-options-project-true: ./node_modules/.bin/eslint . 61.56s user 3.66s system 167% cpu 38.829 total

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