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Bug: [await-thenable] Don't flag values of an unconstrained type parameter #10311

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JoshuaKGoldberg opened this issue Nov 9, 2024 · 1 comment · Fixed by #10314
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accepting prs Go ahead, send a pull request that resolves this issue bug Something isn't working locked due to age Please open a new issue if you'd like to say more. See https://typescript-eslint.io/contributing. package: eslint-plugin Issues related to @typescript-eslint/eslint-plugin

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@JoshuaKGoldberg
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JoshuaKGoldberg commented Nov 9, 2024

Before You File a Bug Report Please Confirm You Have Done The Following...

  • I have tried restarting my IDE and the issue persists.
  • I have updated to the latest version of the packages.
  • I have searched for related issues and found none that matched my issue.
  • I have read the FAQ and my problem is not listed.

Playground Link

https://typescript-eslint.io/play/#ts=5.6.2&fileType=.ts&code=IYZwngdgxgBAZgV2gFwJYHsIwO4CdgAOBAprgDwAqAfABQBuwANgsQFwwUCUMA3gFAwYuYsgS4swbMFTIYDZsQDcfAL5A&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6AQwHd3K78ALRE3YAjJOiiJo0APbRI4MAF8QSoA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA&tokens=false

Repro Code

async function wrapper<T>(value: T) {
  return await value;
}

ESLint Config

module.exports = {
  "rules": {
    "@typescript-eslint/await-thenable": "error"
  }
}

tsconfig

{
  "compilerOptions": {
    "strictNullChecks": true
  }
}

Expected Result

The await value shouldn't be reported on. We don't know that T is or isn't a Promise/Thenable. I'd like to be able to use the await just in case it is.

Actual Result

On the await value:

Unexpected `await` of a non-Promise (non-"Thenable") value.

Additional Info

For a slightly more realistic reproduction, consider a function that awaits the result of calling a function for a generic value:

type GetSomething<T> = (timestamp: number) => T;

async function wrapper<T>(getter: GetSomething<T>) {
  const timestamp = performance.now();

  // I'd like to await in here to preserve the call stack
  return await getter(timestamp);
}

Somewhat related: #8301, where it was noted that the rule intentionally ignores any and unknown values because there's no guarantee they aren't a Promise.

💖

@JoshuaKGoldberg JoshuaKGoldberg added bug Something isn't working package: eslint-plugin Issues related to @typescript-eslint/eslint-plugin triage Waiting for team members to take a look labels Nov 9, 2024
@bradzacher bradzacher added accepting prs Go ahead, send a pull request that resolves this issue and removed triage Waiting for team members to take a look labels Nov 9, 2024
@kirkwaiblinger
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Just want to add that the same fix will need to be propagated to return-await (playground), which contains pesky duplicate logic that we periodically threaten to deprecate (for example #9903)

@github-actions github-actions bot added the locked due to age Please open a new issue if you'd like to say more. See https://typescript-eslint.io/contributing. label Nov 24, 2024
@github-actions github-actions bot locked as resolved and limited conversation to collaborators Nov 24, 2024
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Labels
accepting prs Go ahead, send a pull request that resolves this issue bug Something isn't working locked due to age Please open a new issue if you'd like to say more. See https://typescript-eslint.io/contributing. package: eslint-plugin Issues related to @typescript-eslint/eslint-plugin
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