Autocomplete for overloaded function only suggests first matching signature when discriminant isn't the first field typed

[ajotaos]

🔎 Search Terms

autocomplete discriminated union overloads

🕗 Version & Regression Information

N/A

⏯ Playground Link

https://www.typescriptlang.org/play/?target=9&jsx=0#code/C4TwDgpgBAMglgNwgSQHZgK7CgXigbygGcBjAe0gC4oByAG0QhoG4oAnCOiAQyIgHUIEANbUiwNnFQBzKAF9mAKFCQoAQTp00mbHkKkKEajW6aW7Tjz6CRYiVNkLFigGYZUJYHDKoo0iMDIREQYEEQAFFI61PBI2lgAlMaxTEpuHl4+fgFBIWGR6FjUGlqFwEm0JSyu7p7evv6BwaERUUWwjPHYAD7qml0V4pIyBIpQFsAYbL5twAB0Bqo4y7QMSDRQAPy0KRvGVUpyQA

💻 Code

type LiveInput = { scope: 'live'; releaseWeek: string };
type AllInput = { scope: 'all'; releaseWeek: string };

function getIssues(input: LiveInput): 'Live';
function getIssues(input: AllInput): 'All';
function getIssues(input: LiveInput | AllInput): string {
  return input.scope === 'live' ? 'Live' : 'All';
}

getIssues({ scope: '' })

getIssues({ releaseWeek: '', scope: '' })

🙁 Actual behavior

getIssues({
releaseWeek: '',
scope: '', // ← Only one overload shows up here (the first one, live in this case)
});

🙂 Expected behavior

getIssues({
scope: '', // ← Both overloads show up here
});

Additional information about the issue

Hey TS team 👋

I noticed some inconsistent behavior in autocomplete when using function overloads with object literals that rely on a discriminant field like scope. When you're calling a function with multiple overloads, the order in which you type object fields affects which overloads are shown in IntelliSense — specifically:

If any other fields in the object literal are already written before the discriminant, then autocomplete will only show the first matching overload, even though others should apply too.

This can make it seem like only one overload exists when in reality multiple are valid.

[RyanCavanaugh]

I don't quite understand what you mean. The overload list shows "1/2", so both are there. Can you screenshot?

[ajotaos]

Yeah, sure!

Here we have all autocomplete suggestions being shown when scope is the only parameter in the object:

But if there already is another field present as well, then the suggestion will only show the first function signature overload's discriminant.