Add a warning when using a JSDoc deprecated method

[louy]

So this was previously suggested in microsoft/TypeScript#390, but it seems like it should be in tslint, not typescript.

The idea is when a function which has the tag "@deprecated" is used it should show a warning.
For example:

interface IX {
  /**
   * @deprecated
   */
  function doSomething(): void;
}

class X implements IX {
  function doSomething(): void;

  /**
   * @deprecated
   */
  function doSomethingElse(): void;
}

const x = new X();
x.doSomething(); // Warning: IX.doSomething is deprecated
x.doSomethingElse(); // Warning: X.doSomethingElse is deprecated

Same thing should preferably apply to attributes. Getters & setters.

[adidahiya]

Interesting suggestion. This would involve telling TSLint about your typings files so that it could crawl their JSDoc comments. We don't currently do this, and TSLint would have to treat typings different from sources (don't lint them since they probably don't have the same code style as your sources).

Related:

• Lint Programs as a Whole #680
• Better support for linting multiple files #692 (specifically the part about looking at tsconfig.json to get the list of files to lint)

[louy]

Yeah I agree. As to #680, that was actually one of the first frustrations I had with TSLint, coming from eslint.
I think we're stuck here until those two are closed then.

[punmechanic]

Now that #680 is solved, what's the status on this?

[adidahiya]

Open to PRs. I haven't yet looked at what language service APIs are available for reading JSDoc comments, but feel free to take a crack at it.