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Title: (🐞) false narrowing with reassignment in loop · Issue #11612 · python/mypy · GitHub

Open Graph Title: (🐞) false narrowing with reassignment in loop · Issue #11612 · python/mypy

X Title: (🐞) false narrowing with reassignment in loop · Issue #11612 · python/mypy

Description: a: int | None a = None for i in range(10): reveal_type(a) # "None" and also "int | None" if a: print(a) # error: unreachable a = i Also: a = None for b in [1, 2]: if a is None: a = b continue print("hi") # false unreachable error

Open Graph Description: a: int | None a = None for i in range(10): reveal_type(a) # "None" and also "int | None" if a: print(a) # error: unreachable a = i Also: a = None for b in [1, 2]: if a is None: a = b continue print...

X Description: a: int | None a = None for i in range(10): reveal_type(a) # "None" and also "int | None" if a: print(a) # error: unreachable a = i Also: a = None for b in [1, 2]: if a is None: ...

Opengraph URL: https://github.com/python/mypy/issues/11612

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Domain: github.com

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"(🐞) false narrowing with reassignment in loop","articleBody":"```py\r\na: int | None\r\na = None\r\nfor i in range(10):\r\n    reveal_type(a)  # \"None\" and also \"int | None\"\r\n    if a:\r\n        print(a)  # error: unreachable\r\n    a = i\r\n```\r\n\r\nAlso:\r\n```py\r\na = None\r\nfor b in [1, 2]:\r\n    if a is None:\r\n        a = b\r\n        continue\r\n    print(\"hi\")  # false unreachable error\r\n```","author":{"url":"https://github.com/KotlinIsland","@type":"Person","name":"KotlinIsland"},"datePublished":"2021-11-25T03:54:21.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/11612/mypy/issues/11612"}

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