Weak type not rejected when intersected with `ThisType`

🔎 Search Terms

• function overload
• ThisType
• this

🕗 Version & Regression Information

• This is a crash

⏯ Playground Link

https://www.typescriptlang.org/play?#code/JYOwLgpgTgZghgYwgAgGIHt3IN4ChnJwBcyAzmFKAOa4C+uAJhAgDZxQowCuICYw6EMm4gADAAp2VEuICUyALwA+ZOPzIAZGkzqtAFQAWwUnoCeABwgAeDOiW5ZskgDd0wBo2ZsOwnnwFCIhJSMrrIAArs-HAsNpj2BPpGJhbWtvaOLm4euEHieAD0BcgAegD86sTIAOQAjNV0srk8EnKKKvm4RaUVBFV1DbSOXcUAAmCkALQQAB6WfNNQUOhQzWLibcqqhcXllSS1jU1AA

💻 Code

interface Foo {
  a: string
}
declare function fun0(arg: () => (
  & Foo
  & ThisType<Foo>
)): void
declare function fun0(arg: (
  & Partial<Foo>
  & ThisType<Foo>
)): void

fun0({
// ^? function fun0(arg: (Partial<Foo> & ThisType<Foo>)): void (+1 overload)
  a: '1'
})
fun0(() => ({
// ^? function fun0(arg: () => (Foo & ThisType<Foo>)): void (+1 overload)
  a: '1'
}))
// @ts-expect-error
fun0(() => ({
// ^? function fun0(arg: (Partial<Foo> & ThisType<Foo>)): void (+1 overload)
  a: 1
}))

When I intersect ThisType with a type similar to {} and use it as a function argument, it will always resolve to this declaration.

🙁 Actual behavior

overload to function fun0(arg: (Partial<Foo> & ThisType<Foo>)): void (+1 overload)

🙂 Expected behavior

overload to function fun0(arg: () => (Partial<Foo> & ThisType<Foo>)): void (+1 overload)

Additional information about the issue

When I comment ThisType intesection, it works.

Start with the linked TypeScript Playground example and reproduce the overload-resolution behavior involving ThisType, Foo, and Partial. Trace the compiler's handling of intersections with ThisType and function arguments; done means the third call is rejected and the inferred overload matches the expected function type without a crash.