functions with destructuring parameters are not inferred as type predicate correctly

🔎 Search Terms

infer type predicate, destructuring

🕗 Version & Regression Information

• This changed between versions 5.5
• This changed in commit or PR _______
• This is the behavior in every version I tried, and I reviewed the FAQ for entries about _________
• I was unable to test this on prior versions because _______

⏯ Playground Link

https://www.typescriptlang.org/play/?#code/C4TwDgpgBAGlC8UDeVSQFxQOQEEsG4oBDTAZ2ACcBLAOwHMoBfKAH2VXAkywCECoARmUq0GjfACgANhGBQAHqUwwA2gF0EUdZIkB6XVFIALAPYBXKQBMoNE3IgUKJihIDGJmuSgAzKlOAOEJYAjJgoaFzYeIQkhiL0TOqaihJQUAB0vv4OABQ54ZxMAJQIAHwckAjwiLhYRTrunnJZARRBAExhFZG1McLUCYxJiClpmX6tOfJlCukRVTV49RJAA

💻 Code

type X = { type: 'A'; a: string } | { type: 'B'; b: string };
let xs: X[] = [];

// should not error
const filtered1: { type: 'A'; a: string }[] = xs
  .filter(({ type }) => type === 'A');

const filtered2: { type: 'A'; a: string }[] = xs
  .filter(x => x.type === 'A');

🙁 Actual behavior

error on filtered1

🙂 Expected behavior

not error on filtered1

Additional information about the issue

No response

Start with the linked TypeScript Playground reproduction and compare the destructured-parameter callback with the direct-parameter callback. Trace type-predicate inference for filter callbacks and verify completion when filtered1 accepts the narrowed array type without an error.