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Better narrowing
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Compare
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View reviewed changes
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| Add failing type narrowing test cases | https://github.com/python/mypy/pull/20603/commits/b468db0d308fc8e7108de05070f9ab988f1b0690 |
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Compare
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| January 18, 2026 12:34 | https://github.com/python/mypy/pull/20603#event-22121742144 |
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| Mark failing tests with xfail | https://github.com/python/mypy/pull/20603/commits/f76e174e596507076daca93e67bfe34d4357e050 |
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Compare
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Jan 22, 2026
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View reviewed changes
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| Jan 23, 2026 | https://github.com/python/mypy/pull/20603#issuecomment-3788080297 |
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| Merge commit '11c220778' into xfail-narrowing | https://github.com/python/mypy/pull/20603/commits/dc90f3a53a9a7bfe7537cfc4425a43fb2dc2a750 |
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| January 23, 2026 10:54 | https://github.com/python/mypy/pull/20603#commits-pushed-cf4b12e |
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| Merge remote-tracking branch 'upstream/master' into xfail-narrowing | https://github.com/python/mypy/pull/20603/commits/cf4b12ef68c971408bdfbb09a31b7c68834402f8 |
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Jan 23, 2026
| https://github.com/python/mypy/pull/20603#ref-pullrequest-3848815022 |
|
Narrowing for comparisons against x.__class__
#20642
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