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Title: Extend special case for context-based typevar inference to typevar unions in return position by sterliakov · Pull Request #18976 · python/mypy · GitHub

Open Graph Title: Extend special case for context-based typevar inference to typevar unions in return position by sterliakov · Pull Request #18976 · python/mypy

X Title: Extend special case for context-based typevar inference to typevar unions in return position by sterliakov · Pull Request #18976 · python/mypy

Description: Fixes #17221. Fixes #17654. Fixes #17553. Fixes #17536. Fixes #16659. Fixes #16267. Fixes #15755. Fixes #15150. Fixes #14664. Incidentally improves error message in #12156. Fixes #12092. Fixes #11985. Improves #11455 (but the problem with union TypeVar | SomeFixedType reported in comments there remains). Fixes #10426. When using context, we can perform some overly optimistic inference when return type is T1 | T2. This breaks in important case of builtins.min when default and key are passed, essentially making them always incompatible. This is not the most principled approach, but let's see the primer results. This resolves quite a few issues (some of them duplicates, but some - substantially different), min problem was a very popular one... Diff run: sterliakov/mypy-issues#30

Open Graph Description: Fixes #17221. Fixes #17654. Fixes #17553. Fixes #17536. Fixes #16659. Fixes #16267. Fixes #15755. Fixes #15150. Fixes #14664. Incidentally improves error message in #12156. Fixes #12092. Fixes #119...

X Description: Fixes #17221. Fixes #17654. Fixes #17553. Fixes #17536. Fixes #16659. Fixes #16267. Fixes #15755. Fixes #15150. Fixes #14664. Incidentally improves error message in #12156. Fixes #12092. Fixes #119...

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c4baf4e Extend special-case for context-based typevar inference in return pos… sterliakov Apr 26, 2025 https://github.com/python/mypy/pull/18976/commits/c4baf4ed23b0648198f6e3e32a3d591d850d081c
8331546 Add missing get_proper_type sterliakov Apr 26, 2025 https://github.com/python/mypy/pull/18976/commits/83315466d5114cd61cbe993c9a17389a91dcaef2
7fcae0f Fix a regression with `mapping.get(key, default_singleton)` sterliakov Apr 26, 2025 https://github.com/python/mypy/pull/18976/commits/7fcae0f3ed168eb8044bfb58d6276ebd3b82e385
43c097c Switch to detecting *any* typevar in union in return position - `T | … sterliakov Apr 26, 2025 https://github.com/python/mypy/pull/18976/commits/43c097c4e8ee7889ba256a0d161368cc0cf6ab61
e377115 Revert attempt to fix Mapping.get sterliakov Apr 26, 2025 https://github.com/python/mypy/pull/18976/commits/e3771159078378eb1a2cfc047c959305e0ef40d9
3f04d8e Revert to `all()` - inferring for unions of typevar and something see… sterliakov Apr 27, 2025 https://github.com/python/mypy/pull/18976/commits/3f04d8ee0ad7807867ea952036930d65165df5e2
01cbfbc Merge branch 'master' into bugfix/gh-17221-typevar-union-context sterliakov May 6, 2025 https://github.com/python/mypy/pull/18976/commits/01cbfbcf89cd9d7de5a853bfe13c2cc5138edf08
f1e4dfc Remove xfail test - fixed in previous PR sterliakov May 6, 2025 https://github.com/python/mypy/pull/18976/commits/f1e4dfc60f60ecd64d073dcc519939d5fea023e7
8b5d140 Merge branch 'master' into bugfix/gh-17221-typevar-union-context sterliakov May 14, 2025 https://github.com/python/mypy/pull/18976/commits/8b5d1404487270017097721226856204ddbae779
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