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Douglas Creager cfc6941d5c [red-knot] Resolve references in eager nested scopes eagerly (#16079 )

We now resolve references in "eager" scopes correctly — using the
bindings and declarations that are visible at the point where the eager
scope is created, not the "public" type of the symbol (typically the
bindings visible at the end of the scope).

---------

Co-authored-by: Alex Waygood <alex.waygood@gmail.com>

2025-02-19 10:22:30 -05:00

3.0 KiB

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Comprehensions

Basic comprehensions

class IntIterator:
    def __next__(self) -> int:
        return 42

class IntIterable:
    def __iter__(self) -> IntIterator:
        return IntIterator()

# revealed: int
[reveal_type(x) for x in IntIterable()]

class IteratorOfIterables:
    def __next__(self) -> IntIterable:
        return IntIterable()

class IterableOfIterables:
    def __iter__(self) -> IteratorOfIterables:
        return IteratorOfIterables()

# revealed: tuple[int, IntIterable]
[reveal_type((x, y)) for y in IterableOfIterables() for x in y]

# revealed: int
{reveal_type(x): 0 for x in IntIterable()}

# revealed: int
{0: reveal_type(x) for x in IntIterable()}

Nested comprehension

class IntIterator:
    def __next__(self) -> int:
        return 42

class IntIterable:
    def __iter__(self) -> IntIterator:
        return IntIterator()

# revealed: tuple[int, int]
[[reveal_type((x, y)) for x in IntIterable()] for y in IntIterable()]

Comprehension referencing outer comprehension

class IntIterator:
    def __next__(self) -> int:
        return 42

class IntIterable:
    def __iter__(self) -> IntIterator:
        return IntIterator()

class IteratorOfIterables:
    def __next__(self) -> IntIterable:
        return IntIterable()

class IterableOfIterables:
    def __iter__(self) -> IteratorOfIterables:
        return IteratorOfIterables()

# revealed: tuple[int, IntIterable]
[[reveal_type((x, y)) for x in y] for y in IterableOfIterables()]

Comprehension with unbound iterable

Iterating over an unbound iterable yields Unknown:

# error: [unresolved-reference] "Name `x` used when not defined"
# revealed: Unknown
[reveal_type(z) for z in x]

class IntIterator:
    def __next__(self) -> int:
        return 42

class IntIterable:
    def __iter__(self) -> IntIterator:
        return IntIterator()

# error: [not-iterable] "Object of type `int` is not iterable"
# revealed: tuple[int, Unknown]
[reveal_type((x, z)) for x in IntIterable() for z in x]

Starred expressions

Starred expressions must be iterable

class NotIterable: ...

class Iterator:
    def __next__(self) -> int:
        return 42

class Iterable:
    def __iter__(self) -> Iterator: ...

# This is fine:
x = [*Iterable()]

# error: [not-iterable] "Object of type `NotIterable` is not iterable"
y = [*NotIterable()]

Async comprehensions

Basic

class AsyncIterator:
    async def __anext__(self) -> int:
        return 42

class AsyncIterable:
    def __aiter__(self) -> AsyncIterator:
        return AsyncIterator()

# revealed: @Todo(async iterables/iterators)
[reveal_type(x) async for x in AsyncIterable()]

Invalid async comprehension

This tests that we understand that async comprehensions do not work according to the synchronous iteration protocol

class Iterator:
    def __next__(self) -> int:
        return 42

class Iterable:
    def __iter__(self) -> Iterator:
        return Iterator()

# revealed: @Todo(async iterables/iterators)
[reveal_type(x) async for x in Iterable()]

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