eslint-plugin-tsdoc: Rule to mark types referenced through {@link} and {@inheritDoc} as used

[kraenhansen]

When writing tsdoc strings, it's powerful to be able to reference types from an inline link tag.
It would however be great if the eslint plugin would mark these as used and avoid the @typescript-eslint/no-unused-vars rule reporting types that are only referenced from tsdoc comments as unused.

As an example, the following code

class MyClass {}
/** This comment reference {@link MyClass} but it's still "never used" */
const foo = null;

yields

  1:7  warning  'MyClass' is defined but never used       @typescript-eslint/no-unused-vars
  3:7  warning  'foo' is assigned a value but never used  @typescript-eslint/no-unused-vars

and I would love for that first line to go away.

This is already supported for plain (non inline tags) by the jsdoc plugin, through the use of the eslint SourceCode#markVariableAsUsed API, but it doesn't yet support inline tags and it would be great to have this supported in the eslint-plugin-tsdoc directly.

I'd be interested in submitting a PR for this, if this is interesting for the maintainers.

[cowwoc]

For what it's worth, I'm also constantly tripping across this issue.

@octogonz can we have your blessing for @kraenhansen to submit a PR?

[octogonz]

Sure, sounds good to me. 🙂 I am on vacation this week but will have more time to investigate this next week.

[octogonz]

Just to clarify, the PR would probably be for the typescript-eslint project, not eslint-plugin-tsdoc, right?

[kraenhansen]

I'm on vacation these days too and probably won't be looking into this for the next two weeks.

PR would probably be for the typescript-eslint project, not eslint-plugin-tsdoc, right

I'm not deeply familiar with the architecture of this project, but when I did similar work for the jsdoc plugin, it was valuable to implement this as a rule as it was responsible for parsing docs comments. It also seemed to make it easier for end-users to enable / disable and configure.

[cowwoc]

@kraenhansen any progress on this issue?

[kraenhansen]

@cowwoc some .. I spent a bit of time on this today.

I think I initially got stuck understanding where the fix actually belonged.

PR would probably be for the typescript-eslint project, not eslint-plugin-tsdoc, right

Reading this thread on the typescript-eslint project it seems they expect another plugin to be parsing these doc strings to marking symbols as used, which is why I believe I created this issue for eslint-plugin-tsdoc in the first place.

I did a POC of an implementation here: #423 and I've later realized the architecture I choose needs to be revisited. I'll need to add a dependency on @typescript-eslint/utils to retrieve and reference type information.