[ty] Fix incorrect types inferred when unpacking mixed tuples#23437
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charliermarsh merged 1 commit intomainfrom Feb 20, 2026
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[ty] Fix incorrect types inferred when unpacking mixed tuples#23437charliermarsh merged 1 commit intomainfrom
charliermarsh merged 1 commit intomainfrom
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Typing conformance resultsNo changes detected ✅ |
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Memory usage reportMemory usage unchanged ✅ |
charliermarsh
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Oh, that was easy 😆 nice work!
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…-sh#23437) ## Summary When unpacking a "mixed tuple" like `tuple[I0, *tuple[I1, ...], I2]` with a starred expression (e.g., `[a, b, *c] = x`), ty incorrectly inferred `I1` for `b` instead of `I1 | I2`. The variable-length part can materialize to 0 elements, causing `I2` to shift into the `b` position, so the correct type is the union `I1 | I2`. Closes: astral-sh/ty#947.
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Summary
When unpacking a "mixed tuple" like
tuple[I0, *tuple[I1, ...], I2]with a starred expression (e.g.,[a, b, *c] = x), ty incorrectly inferredI1forbinstead ofI1 | I2. The variable-length part can materialize to 0 elements, causingI2to shift into thebposition, so the correct type is the unionI1 | I2.Closes: astral-sh/ty#947.