Incorrect type inference in Object.entries and Object.values if type has optional value

[Crinax]

🔎 Search Terms

object.entries, object.values, type inference, incorrect type inference,

🕗 Version & Regression Information

• This changed between versions 4.5.5 and 6.0 (nightly)

⏯ Playground Link

https://www.typescriptlang.org/play/?noUncheckedIndexedAccess=true&noPropertyAccessFromIndexSignature=true#code/C4TwDgpgBAyg9gWwgaQiAzlAvFA5AQ1ygB88AjI03AY1wG4AoUSKANXwBsBXaHdYAE4BLAHYBzRgybhoAFQj8A8mQBW2KAG8GUHVADaAayijYiFGnQBdAPwAuNpx6MAvlI4RgUCPflLV6rV0ofHsuEQATCAAzUQhwhlcpAHok2AALOC4OcKgyaD1+YXEAGihC0TESKDDImJE4yz1LBndPCABREUEhBXVlFQhqYAA6CC7hBQAKCABKOigU-XKSsu7xRuaGRZgMrJy8qEnlytIa6NjwmaaWjy92bl6cfsGRgDdHKdn5xeOmoA

💻 Code

type SomeKeys = 'a' | 'b' | 'c';
type Value = string;


type TestObj = {
    [k in SomeKeys]?: Value;
}

let e: TestObj = {
    a: undefined
}


// Should be [string, string | undefined][]
let eEntries = Object.entries(e); // [string, string][]

// Should be (string | undefined)[]
let eValues = Object.values(e); // string[]

🙁 Actual behavior

• Type of result of Object.entries is a [string, T]
• Type of result of Object.values is a T[]

🙂 Expected behavior

• Type of result of Object.entries should be a [string, T | undefined] if optional property exists
• Type of result of Object.values should be a (T | undefined)[] if optional property exists

Additional information about the issue

No response

[MartinJohns]

Duplicate of #52045.