Regression when spreading Types in an Alias: TS1265: A rest element cannot follow another rest element.

[pfeileon]

🔎 Search Terms

TS1265

🕗 Version & Regression Information

• This changed between versions 5.3.3 and 5.4.2

⏯ Playground Link

https://www.typescriptlang.org/play?ts=5.4.2#code/MYewdgzgLgBAZgSwE7QPICMBWBTYsC8MA3nCCAFwwDkpIVAvjAIYQyiRQDcAUO9DBFzgAJhhx4YhIuiZJKVGUgbNWfLt17h+iFFADCWqEzAEYAbSpMANlaoAaGADpnACjG4ojgNbYAnhBcdNCwPAEpQgF0VNkMeNQEhMGEDDmNTC2tbB2dHNxC8bz8AwXZRfKhwqJYYjh5uKF8AB2wYADFkaAAVJpbCBuaQOHgO-UM0nn6WgGVE4W7myRhJwYTSlOhxjUmYAwBbdAQwbDmexaRsJmFwK19zbhgnZ3bdeew7e8fHGdLX94ieIA

💻 Code

const firstObject = {foo: 'foo'} as const;
const secondObject = {bar: 'bar'} as const;

const firstConstant = ['all', ...(Object.keys(firstObject))] as const;
const secondConstant = ['all', ...(Object.keys(secondObject))] as const;

type FirstType = typeof firstConstant;
type SecondType = typeof secondConstant;

type CombinedType = readonly [
  ...FirstType,
  ...SecondType,
];

Workbench Repro

🙁 Actual behavior

A rest element cannot follow another rest element.(1265)

🙂 Expected behavior

No error

Additional information about the issue

No response

[Andarist]

This is working as intended now and was changed here, see the discussion before this comment

[pfeileon]

This is working as intended now and was changed here, see the discussion before this comment

Is it? In my example it's all strings, the tuples aren't of mixed types.

[Andarist]

It doesn't matter what are the types contained in those arrays. The reported error is pretty generic and is only concerned with the fact that you are using multiple rest elements:

A rest element cannot follow another rest element.(1265)

[typescript-bot]

This issue has been marked as "Working as Intended" and has seen no recent activity. It has been automatically closed for house-keeping purposes.