Add support for lazy import parsing#23755
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charliermarsh merged 1 commit intomainfrom Mar 6, 2026
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Typing conformance resultsNo changes detected ✅Current numbersThe percentage of diagnostics emitted that were expected errors held steady at 87.07%. The percentage of expected errors that received a diagnostic held steady at 77.62%. |
Memory usage reportMemory usage unchanged ✅ |
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dhruvmanila
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Mar 6, 2026
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dhruvmanila
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Looks great, thanks!
I've also omitted support for flagging semantic syntax errors (e.g.,
lazy importinsidedef).
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MichaReiser
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Mar 6, 2026
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Probably fine for now, but this causes ❯ echo "lazy import os" | cargo run -p ruff -- check --no-cache --isolated --select I --output-format concise --fix -
import os
Found 1 error (1 fixed, 0 remaining). |
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Oh nice thank you, I will fix that. |
charliermarsh
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Mar 6, 2026
## Summary We now reject cases like: - `lazy import ...` inside functions, including `async def` - `lazy from ... import ...` inside functions, including `async def` - `lazy import ...` and `lazy from ... import ...` inside class bodies - `lazy import ...` and `lazy from ... import ...` anywhere inside a `try` statement, including `except` / `except*` - `lazy from ... import *` anywhere - `lazy from __future__ import ...` anywhere A follow-up to #23755. See: #21305.
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Summary
This PR adds
is_lazyto the AST and parser, and supportslazyimport formatting in the formatter. The nameis_lazymatches the CPython AST, though we could modify it if there's demand.There are no further changes to Ruff rules or even to Ruff import sorting, since those deserve separate design discussions.
I've also omitted support for flagging semantic syntax errors (e.g.,
lazy importinsidedef).See: #21305.