Wrong type infer for spread arrays

[worudso]

TypeScript Version: 3.6.0-dev.20190606

Search Terms:
spread, array
Code

const a = {
  ...[1, 2, 3],
};
a.slice // === undefined actually!
console.log(a.slice);

Expected behavior:
a doesn't have slice property
Actual behavior:
a has slice property for Array type.
Playground Link:
https://www.typescriptlang.org/play/#src=const%20a%20%3D%20%7B%0D%0A%20%20...%5B1%2C%202%2C%203%5D%2C%0D%0A%7D%3B%0D%0Aa.slice%20%2F%2F%20%3D%3D%3D%20undefined%20actually!%0D%0Aconsole.log(a.slice)%3B
Related Issues:

[fatcerberus]

...wait, is that even a legal thing to do? Spreading an array into an object like that?

[worudso]

It works. In that case, you got { 0: 1, 1: 2, 2: 3 } for a.
I know it's not recommended even possible, but I found a special use case for it. #31575 (comment)

[fatcerberus]

Yeah, arrays are just objects like almost everything else in JS, of course that would work. Brainfart on my part, ignore my stupidity. 😄

[AnyhowStep]

#28801

[RyanCavanaugh]

#9726

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.