Generic function with function as argument autocomplete broken, unless generic argument of the argument function is it's first argument

🔎 Search Terms

typescript generic function no autocomplete function as argument

🕗 Version & Regression Information

Relevant versions are 5.4.5 and above, tested in all versions from 5.4.5 to 5.8.0 (Nightly) inclusive, I was able to reproduce the bug in all versions.

⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.7.2#code/IYZwngdgxgBAZgV2gFwJYHsIwE4FMDmqIyu2ACgDYKEQBCwAJgDwDyADsjLgB4kQMgYAJVxR02ZsWyoI+ADQxgEMAD4VACijAKFAEbAoAawBcMdcDZtTSsAvQcMEEKfbIAlDAC8KmADd0qAx2HM4wAHLoAJIQcKSsHCpupmTY6AC2RLhM-oE+AN4AvgBQRXiExKSU1DL0DOrmlsHIoXkwIOm4yAAWMvimUr0wBR7eMIUKeUUwMAD0MzC6uBToAO6KCMjoYmlsFJ24MEQLqYa4EAq4vmcw3ejUXTddB8hgbAdHbKlv2BRgftqBYAkBhTNodIrDADcJSKc0OEBIeGIvV+CmAGy26V2+xgK3EhkEqDgMAARPY0JgQCTFNh8Ag0mdONtcII4KhsMQFHBxFxuMAdntjEVQJBYIgUI4cAQiIiqjQAOLodDMVy8vgCYSicSSZDSWRo5RqTTaPQGExmcmOUKuNGWazKEY+HJBGDk0IRaKxbDxZCJZKpDIgLLO-LFUrSirkKgKpV1dRu0ytdoM7q9fq6wYFW1WRQOryhiaguGLZZrdGbbbYki4-EgUHJ3AQtyQoA

💻 Code

async function registerPluginBad<Opt extends Record<string, any>>(callback: (app: any, options: Opt) => void, opts: NoInfer<Opt>): Promise<void> {}

registerPluginBad((app, opts: { something: string }) => {}, {
  // below autocomplete is broken, even though the type is properly validated
  some
});


// interestingly, autocomplete works if "options" argument comes first, for example:
async function registerPluginGood<Opt extends Record<string, any>>(callback: (options: Opt, app: any) => void, opts: NoInfer<Opt>): Promise<void> {}

registerPluginGood((opts: { something: string }, app: any) => {}, {
  // below autocomplete works
  some
});

🙁 Actual behavior

This one has to be tested in the playground:
registerPluginBad - second argument does not autocomplete, however type is properly validated
registerPluginGood - exact same function, except the first argument "callback" arguments have changed the order, which for some reason fixes the autocomplete

🙂 Expected behavior

For both functions, autocomplete should work. Argument order should not matter.
Both do not infer from "opts", so any inference should be from "options" argument of the callback.

Additional information about the issue

No response

リンク先の TypeScript Playground を開き、registerPluginBad と registerPluginGood の違いを再現してください。callback パラメーターの順序に対する自動補完とジェネリック推論の動作を追跡してください。完了の条件は、両方の呼び出しで options オブジェクトの補完が提供され、型検証も維持されることです。