Symlinks cause parserOptions.project errors

[nikparo]

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have read the FAQ and my problem is not listed.

Repro

https://github.com/nikparo/ts-eslint-symlinks

Expected Result

The targeted directories and files should be linted, whether or not there are symlinks elsewhere pointing at them.

Actual Result

If there is a symlink somewhere pointing at a directory, then linting it will throw Parsing error: "parserOptions.project" has been set for @typescript-eslint/parser. errors. At least if the symlink alphabetically comes before the directory.

> ts-eslint-symlinks@0.0.0 lint /Users/nik/Projects/tmp/ts-eslint-symlinks
> eslint libs/symlinked-lib/**/*.ts

  typescript-eslint:typescript-estree:parser parserOptions.project (excluding ignored) matched projects: Set { '/users/nik/projects/tmp/ts-eslint-symlinks/tsconfig.base.json' } +0ms
  typescript-eslint:typescript-estree:createProjectProgram Creating project program for: /Users/nik/Projects/tmp/ts-eslint-symlinks/libs/symlinked-lib/src/index.ts +0ms
  typescript-eslint:typescript-estree:createWatchProgram File did not belong to any existing programs, moving to create/update. /users/nik/projects/tmp/ts-eslint-symlinks/libs/symlinked-lib/src/index.ts +0ms
  typescript-eslint:typescript-estree:createWatchProgram Creating watch program for /users/nik/projects/tmp/ts-eslint-symlinks/tsconfig.base.json. +0ms

/Users/nik/Projects/tmp/ts-eslint-symlinks/libs/symlinked-lib/src/index.ts
  0:0  error  Parsing error: "parserOptions.project" has been set for @typescript-eslint/parser.
The file does not match your project config: libs/symlinked-lib/src/index.ts.
The file must be included in at least one of the projects provided

By deleting the symlink apps/legacy-app/libs (which points at libs) the errors go away. Whether the symlink is ignored or not using ignorePatterns does not seem to matter.

Additional Info

I believe I have tracked this down to the use of updatedProgram.getRootFileNames() in createWatchProgram.js. That method call seems to only get the first instance of a symlinked file. I.e. apps/legacy-app/libs/symlinked-lib/src/index.ts will be in the returned fileList, but libs/symlinked-lib/src/index.ts will not.

Versions

package	version
@typescript-eslint/typescript-estree	4.14.1
TypeScript	4.1.3
node	v12.20.0

[bradzacher]

We build on top of TypeScript and eslint, and we delegate all file reading to those packages.

I haven't looked into it, but I don't know it there's much we can do without reading from disk and attempting to pre-empt what TS is doing to normalise the file paths.

Attempting to encode knowledge about how TS/ESLint handle symlinks is also a recipe for disaster when TS releases a new version or ESLint releases a major.

Additionally disk reads aren't cheap so IDK if it's a great idea to just build into the regular flow.

Symlinks are also a pretty rare usecase in the community (hence this is the first time someone has reported this), so I'm not sure how much effort is worth putting into this.
If you want to look into this, I'm happy to find out the results of a deeper investigation! I can answer any questions you might have.

I'd be looking for a champion to work on this, as I don't have the time to look into this niche of an issue (similar to vue support - vuejs/eslint-plugin-vue#1296)

[nikparo]

Unfortunately I don't really know any of the technologies very well, otherwise I may have dug into it a bit further. I'm currently more inclined to try and structure my project a bit differently instead to work around the issue.

I did notice though that TS seems to have some symlink functionality built in, as updatedProgram also has a getSymlinkCache function. It didn't provide anything of immediate value though.

[armano2]

i'm going to look into this

[armano2]

i have few news about this issue, and this seem to be caused by our normalization of paths <- that was a fix introduced to fix issues with editors

i can confirm that i can reproduce this issue on linux

[larshp]

any workarounds possible?