Literal composition

[Dreamsorcerer]

Could be nice to support composition of literals, so that something like this type checks correctly:

from typing import Literal

def page(page: Literal["p1", "p2"]): ...

def foo(num: Literal["1", "2"]):
    page(f"p{num}")
    page("p" + num)
    page("p" + "1")

[sobolevn]

Related https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html

[brianschubert]

Closing as duplicate of #11990, which was opened later but has more discussion and seems to be the canonical issue linked to by other issues and PRs.