mirror of https://github.com/astral-sh/ruff.git synced 2025-09-30 22:01:47 +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

3.6 KiB

Raw Blame History

String annotations

Simple

def f(v: "int"):
    reveal_type(v)  # revealed: int

Nested

def f(v: "'int'"):
    reveal_type(v)  # revealed: int

Type expression

def f1(v: "int | str", w: "tuple[int, str]"):
    reveal_type(v)  # revealed: int | str
    reveal_type(w)  # revealed: tuple[int, str]

Partial

def f(v: tuple[int, "str"]):
    reveal_type(v)  # revealed: tuple[int, str]

Deferred

def f(v: "Foo"):
    reveal_type(v)  # revealed: Foo

class Foo: ...

Deferred (undefined)

# error: [unresolved-reference]
def f(v: "Foo"):
    reveal_type(v)  # revealed: Unknown

Partial deferred

def f(v: int | "Foo"):
    reveal_type(v)  # revealed: int | Foo

class Foo: ...

`typing.Literal`

from typing import Literal

def f1(v: Literal["Foo", "Bar"], w: 'Literal["Foo", "Bar"]'):
    reveal_type(v)  # revealed: Literal["Foo", "Bar"]
    reveal_type(w)  # revealed: Literal["Foo", "Bar"]

class Foo: ...

Various string kinds

def f1(
    # error: [raw-string-type-annotation] "Type expressions cannot use raw string literal"
    a: r"int",
    # error: [fstring-type-annotation] "Type expressions cannot use f-strings"
    b: f"int",
    # error: [byte-string-type-annotation] "Type expressions cannot use bytes literal"
    c: b"int",
    d: "int",
    # error: [implicit-concatenated-string-type-annotation] "Type expressions cannot span multiple string literals"
    e: "in" "t",
    # error: [escape-character-in-forward-annotation] "Type expressions cannot contain escape characters"
    f: "\N{LATIN SMALL LETTER I}nt",
    # error: [escape-character-in-forward-annotation] "Type expressions cannot contain escape characters"
    g: "\x69nt",
    h: """int""",
    # error: [byte-string-type-annotation] "Type expressions cannot use bytes literal"
    i: "b'int'",
):
    reveal_type(a)  # revealed: Unknown
    reveal_type(b)  # revealed: Unknown
    reveal_type(c)  # revealed: Unknown
    reveal_type(d)  # revealed: int
    reveal_type(e)  # revealed: Unknown
    reveal_type(f)  # revealed: Unknown
    reveal_type(g)  # revealed: Unknown
    reveal_type(h)  # revealed: int
    reveal_type(i)  # revealed: Unknown

Various string kinds in `typing.Literal`

from typing import Literal

def f(v: Literal["a", r"b", b"c", "d" "e", "\N{LATIN SMALL LETTER F}", "\x67", """h"""]):
    reveal_type(v)  # revealed: Literal["a", "b", b"c", "de", "f", "g", "h"]

Class variables

MyType = int

class Aliases:
    MyType = str

    forward: "MyType"
    not_forward: MyType

reveal_type(Aliases.forward)  # revealed: str
reveal_type(Aliases.not_forward)  # revealed: str

Annotated assignment

a: "int" = 1
b: "'int'" = 1
c: "Foo"
# error: [invalid-assignment] "Object of type `Literal[1]` is not assignable to `Foo`"
d: "Foo" = 1

class Foo: ...

c = Foo()

reveal_type(a)  # revealed: Literal[1]
reveal_type(b)  # revealed: Literal[1]
reveal_type(c)  # revealed: Foo
reveal_type(d)  # revealed: Foo

Parameter

TODO: Add tests once parameter inference is supported

Invalid expressions

The expressions in these string annotations aren't valid expressions in this context but we shouldn't panic.

a: "1 or 2"
b: "(x := 1)"
c: "1 + 2"
d: "lambda x: x"
e: "x if True else y"
f: "{'a': 1, 'b': 2}"
g: "{1, 2}"
h: "[i for i in range(5)]"
i: "{i for i in range(5)}"
j: "{i: i for i in range(5)}"
k: "(i for i in range(5))"
l: "await 1"
# error: [invalid-syntax-in-forward-annotation]
m: "yield 1"
# error: [invalid-syntax-in-forward-annotation]
n: "yield from 1"
o: "1 < 2"
p: "call()"
r: "[1, 2]"
s: "(1, 2)"

3.6 KiB Raw Blame History