ObjectConstructor.assign

[TrejGun]

TypeScript Version: 3.7.2

Search Terms:
ObjectConstructor, Object, assign, target, null

Code

Object.assign(null, {a:1})

this works because

    assign<T, U>(target: T, source: U): T & U;

but T can't be null

Expected behavior:
type error is risen ts and reported by typescript-eslint

Actual behavior:
type error in js

TypeError: Cannot convert undefined or null to object
    at Function.assign (<anonymous>)

Playground Link:
http://www.typescriptlang.org/play/?ssl=1&ssc=26&pln=1&pc=21#code/PIIwVgpgxgLgdAQwM5IJYHMB2AKTBXAGwIBoACAbwQC4BGAXwEog

Related Issues:
#3429

[fatcerberus]

The typing used to be correct as the default constraint for a generic type parameter was at one time {}. It is now unknown so that should probably be changed to T extends {} to exclude null/undefined.

[TrejGun]

Guys, as I understand the fix is available for almost half a year already. What prevents it from being merged?

[sandersn]

We need to make sure it doesn't cause a lot of breaking changes. I ran the user tests and Definitely Typed tests to see what code there might break.