Fix: internal error caused by the generic type alias with an unpacked list #20689
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Updated type alias test cases to reflect syntax changes.
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Update error messages for invalid syntax in type alias tests.
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Add tests for type alias unpacking with lists.
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Update type alias tests to reflect unpacking errors for list[int].
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ilevkivskyi
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Jan 29, 2026
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Not a full review, just something for you while you are fixing the tests.
| unpacked = get_proper_type(item.type) | ||
| if isinstance(unpacked, Instance): | ||
| assert unpacked.type.fullname == "builtins.tuple" | ||
| if unpacked.type.fullname != "builtins.tuple": |
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Please add a comment above this line explaining that expand_type() may be called during semantic analysis, before invalid unpacks are fixed.
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Add comment to clarify behavior during semantic analysis.
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Updated test cases for TypeAlias unpacking in Python.
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Removed xfail marker from test case and updated comments for clarity.
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Add test cases for unpacked type aliases in Python 3.10 and 3.11
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Update error messages for type alias unpacking tests.
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Update error messages for unpacking list in type alias tests to reflect Python version requirements.
Updated error messages for unpacking list[int] in type alias tests.
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Updated type alias test cases to reflect syntax changes in Python 3.11.
Updated test cases to reflect unpacking rules for TypeAlias.
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Update comments to clarify expectations for unpacking lists in type aliases.
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According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
ilevkivskyi
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Jan 30, 2026
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| # Only "Test suite with py310-ubuntu, mypyc-compiled" expects: Invalid syntax | ||
| # The other tests expect: "list[int]" cannot be unpacked (must be tuple or TypeVarTuple) | ||
| # v1: TA[*list[int]] |
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If you want to test the new *-syntax, you should move the test to check-python311.test, then you will not need all these dances with having two separate tests, etc.
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Fixes: #20549