mirror of https://github.com/astral-sh/ruff.git synced 2025-10-02 14:52:01 +00:00

Shaygan Hooshyari 03ff883626

Display Union of Literals as a Literal (#14993 )

## Summary

Resolves #14988

Display union of Literals like other type checkers do.

With this change we lose the sorting behavior. And we show the types as
they appeared. So it's deterministic and tests should not be flaky.
This is similar to how Mypy [reveals the
type](https://mypy-play.net/?mypy=latest&python=3.12&gist=51ad03b153bfca3b940d5084345e230f).

In some cases this makes it harder to know what is the order in revealed
type when writing tests but since it's consistent after the test fails
we know the order.

## Test Plan

I adjusted mdtests for this change. Basically merged the int and string
types of the unions.

In cases where we have types other than numbers and strings like this
[one](https://github.com/astral-sh/ruff/pull/14993/files#diff-ac50bce02b9f0ad4dc7d6b8e1046d60dad919ac52d0aeb253e5884f89ea42bfeL51).
We only group the strings and numbers as the issue suggsted.

```
def _(flag: bool, flag2: bool):
    if flag:
        f = 1
    elif flag2:
        f = "foo"
    else:
        def f() -> int:
            return 1
    # error: "Object of type `Literal[1, "foo", f]` is not callable (due to union elements Literal[1], Literal["foo"])"
    # revealed: Unknown | int
    reveal_type(f())
```

[pyright
example](https://pyright-play.net/?code=GYJw9gtgBALgngBwJYDsDmUkQWEMoAySMApiAIYA2AUNQCYnBQD6AFMJeWgFxQBGYMJQA0UDlwBMvAUICU3alCWYm4nouWamAXigBGDUpKUkqzmimHNYqLoBEwQXavGAziQXXlDVa1lQAWgA%2BTBQYTy9rEBIYAFcQFH0rAGIoMnAQXjsAeT4AKxIAY3wwJngEEigAAyJSCkoAbT1RBydRYABdKsxXKBQwfEKqTj5KStY6WMqYMChYlCQwROMSCBIw3tqyKiaO0S36htawOw7ZZ01U6IA3EioSOl4AVRQAa36Ad0SAH1CYKxud0ozHKJHYflk1CAA)

[mypy
example](https://mypy-play.net/?mypy=latest&python=3.12&gist=31c8bdaa5521860cfeca4b92841cb3b7)

---------

Co-authored-by: Carl Meyer <carl@oddbird.net>

2025-01-08 00:58:38 +00:00

1.7 KiB

Raw Blame History

Unions in calls

Union of return types

def _(flag: bool):
    if flag:
        def f() -> int:
            return 1
    else:
        def f() -> str:
            return "foo"
    reveal_type(f())  # revealed: int | str

Calling with an unknown union

from nonexistent import f  # error: [unresolved-import] "Cannot resolve import `nonexistent`"

def coinflip() -> bool:
    return True

if coinflip():
    def f() -> int:
        return 1

reveal_type(f())  # revealed: Unknown | int

Non-callable elements in a union

Calling a union with a non-callable element should emit a diagnostic.

def _(flag: bool):
    if flag:
        f = 1
    else:
        def f() -> int:
            return 1
    x = f()  # error: "Object of type `Literal[1] | Literal[f]` is not callable (due to union element `Literal[1]`)"
    reveal_type(x)  # revealed: Unknown | int

Multiple non-callable elements in a union

Calling a union with multiple non-callable elements should mention all of them in the diagnostic.

def _(flag: bool, flag2: bool):
    if flag:
        f = 1
    elif flag2:
        f = "foo"
    else:
        def f() -> int:
            return 1
    # error: "Object of type `Literal[1, "foo"] | Literal[f]` is not callable (due to union elements Literal[1], Literal["foo"])"
    # revealed: Unknown | int
    reveal_type(f())

All non-callable union elements

Calling a union with no callable elements can emit a simpler diagnostic.

def _(flag: bool):
    if flag:
        f = 1
    else:
        f = "foo"

    x = f()  # error: "Object of type `Literal[1, "foo"]` is not callable"
    reveal_type(x)  # revealed: Unknown

1.7 KiB Raw Blame History