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Title: Retain `None` as constraints bottom if no bottoms were provided by sterliakov · Pull Request #19485 · python/mypy · GitHub

Open Graph Title: Retain `None` as constraints bottom if no bottoms were provided by sterliakov · Pull Request #19485 · python/mypy

X Title: Retain `None` as constraints bottom if no bottoms were provided by sterliakov · Pull Request #19485 · python/mypy

Description: Current version replaces None (which indicates "no items") with an empty union (=Uninhabited). This breaks inference in some cases. Fixes #19483.

Open Graph Description: Current version replaces None (which indicates "no items") with an empty union (=Uninhabited). This breaks inference in some cases. Fixes #19483.

X Description: Current version replaces None (which indicates "no items") with an empty union (=Uninhabited). This breaks inference in some cases. Fixes #19483.

Opengraph URL: https://github.com/python/mypy/pull/19485

X: @github

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Show all changes 3 commits https://github.com/python/mypy/pull/19485/files
1da86bb Retain `None` as constraints bottom if no bottoms were provided sterliakov Jul 21, 2025 https://github.com/python/mypy/pull/19485/commits/1da86bbb7c71be06fae5db85162c923b9092aa87
2ca095d Add testcase sterliakov Jul 21, 2025 https://github.com/python/mypy/pull/19485/commits/2ca095d1d746ae14ff9e62fdc0022d5fab4a9801
82f3c74 Stop testing iterables for truthiness! sterliakov Jul 21, 2025 https://github.com/python/mypy/pull/19485/commits/82f3c7421fdd11422885698a33af2a64f63084ba
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