[ty] Infer precise types for bit-shift operations on integer literals#23301
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AlexWaygood merged 2 commits intomainfrom Feb 16, 2026
Merged
[ty] Infer precise types for bit-shift operations on integer literals#23301AlexWaygood merged 2 commits intomainfrom
AlexWaygood merged 2 commits intomainfrom
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…rflow - Support literal int inference for `<<` and `>>` operators - Use `checked_neg()` for unary negation to handle i64::MIN overflow - Add overflow detection for left shifts into the sign bit using a leading-bits headroom check: count redundant sign-extension bits to determine how far a value can be shifted without overflowing i64 - Add tests for bitshift arithmetic with booleans and integers https://claude.ai/code/session_01MPdchMiqZsZQ2Le3JV9aWf
Typing conformance resultsNo changes detected ✅ |
|
Memory usage reportMemory usage unchanged ✅ |
AlexWaygood
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carljm,
dcreager,
ibraheemdev and
sharkdp
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AlexWaygood
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Feb 16, 2026
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Looks good!
Codex notes two edge-case precision issues; I'm not sure we care, but in case you want to fix them up:
0 << nis inferred asintfor large non-negative n, but Python result is always exactly 0.- Very large right-shift counts (> u32::MAX) lose literal precision:
- ty:
reveal_type(1 >> 5000000000) => int,reveal_type(-1 >> 5000000000) => int - Python:
1 >> 5000000000 => 0,-1 >> 5000000000 => -1
- ty:
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Summary
Fixes astral-sh/ty#517.
This PR revives #18329 / #19281, but without the controversial bit of those PRs (the new diagnostic). Rather than adding a new diagnostic if an integer is left-shifted or right-shifted by a negative number, we just ignore that and infer
int. We can always add a new diagnostic later, if we find consensus on it.Along the way, Claude also discovered that
reveal_type(-(-9223372036854775807 - 1))currently revealsLiteral[-9223372036854775808]onmain, which is... not correct. So this PR fixes that too.Test Coverage
mdtests
Co-authored-by: Brandt Bucher [email protected]