Before You File a Proposal Please Confirm You Have Done The Following...

• I have searched for related issues and found none that match my proposal.
• I have searched the current rule list and found no rules that match my proposal.
• I have read the FAQ and my problem is not listed.

My proposal is suitable for this project

• My proposal specifically checks TypeScript syntax, or it proposes a check that requires type information to be accurate.
• My proposal is not a "formatting rule"; meaning it does not just enforce how code is formatted (whitespace, brace placement, etc).
• I believe my proposal would be useful to the broader TypeScript community (meaning it is not a niche proposal).

Description

TypeScript now supports Disposables: objects that have some "dispose" behavior when they go out of scope.

It's important to use using and not const/let when using those objects, otherwise the automatic cleanup does not happen and you would leak resources.

Fail Cases

In this case we are opening a file through an API that expects to be disposed, but we are not using it as such. The readConfig function will thus leak resources associated to the opened file.

declare function openFile(url: string): Disposable & MyFileAPI;

function readConfig() {
  const configFile = openFile("./configFile");
  return configFile.contentsAsJson();
}

Pass Cases

In this case we are properly disposing the file resource.

declare function openFile(url: string): Disposable & MyFileAPI;

function readConfig() {
  using configFile = openFile("./configFile");
  return configFile.contentsAsJson();
}

Additional Info

This is the equivalent to require-await, but for Disposables rather than Thenables.