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[red-knot] Detect division-by-zero in unions and intersections#17157

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sharkdp merged 1 commit intomainfrom
david/division-by-zero-unions
Apr 2, 2025
Merged

[red-knot] Detect division-by-zero in unions and intersections#17157
sharkdp merged 1 commit intomainfrom
david/division-by-zero-unions

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@sharkdp sharkdp commented Apr 2, 2025

Summary

Yet another instance of "we should have handled unions and intersections correctly". With this PR, we emit a diagnostic for this case where previously didn't:

from typing import Literal

def f(m: int, n: Literal[-1, 0, 1]):
    # error: [division-by-zero] "Cannot divide object of type `int` by zero"
    return m / n

The new Boolean flag is not pretty, but without it, we emit multiple diagnostics for a single expression in some cases. Let me know if you have better ways to address this.

Test Plan

New Markdown test

@sharkdp sharkdp added the ty Multi-file analysis & type inference label Apr 2, 2025
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github-actions bot commented Apr 2, 2025

mypy_primer results

No ecosystem changes detected ✅

@sharkdp sharkdp merged commit af988bf into main Apr 2, 2025
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@sharkdp sharkdp deleted the david/division-by-zero-unions branch April 2, 2025 16:21
dcreager added a commit that referenced this pull request Apr 3, 2025
* origin/main: (35 commits)
  [red-knot] Callable types are disjoint from literals (#17160)
  [red-knot] Fix inference for `pow` between two literal integers (#17161)
  [red-knot] Add GitHub PR annotations when mdtests fail in CI (#17150)
  [red-knot] Fix equivalence of differently ordered unions that contain `Callable` types (#17145)
  [red-knot] Add initial set of tests for unreachable code (#17159)
  [`airflow`] Move `AIR302` to `AIR301` and `AIR303` to `AIR302` (#17151)
  ruff_db: simplify lifetimes on `DiagnosticDisplay`
  [red-knot] Detect division-by-zero in unions and intersections (#17157)
  [`airflow`] Add autofix infrastructure to `AIR302` name checks (#16965)
  [`flake8-bandit`] Mark `str` and `list[str]` literals as trusted input (`S603`) (#17136)
  [`airflow`] Add autofix for `AIR302` attribute checks (#16977)
  [`airflow`] Extend `AIR302` with additional symbols (#17085)
  [`airflow`] Move `AIR301` to `AIR002` (#16978)
  [`airflow`] Add autofix for `AIR302` method checks (#16976)
  ruff_db: switch diagnostic rendering over to `std::fmt::Display`
  [red-knot] Add 'Goto type definition' to the playground (#17055)
  red_knot_ide: update snapshots
  red_knot_python_semantic: remove comment about `TypeCheckDiagnostic`
  ruff_db: delete most of the old diagnostic code
  red_knot: use `Diagnostic` inside of red knot
  ...
dcreager added a commit that referenced this pull request Apr 3, 2025
* origin/main: (82 commits)
  [red-knot] Fix more [redundant-cast] false positives (#17170)
  [red-knot] Three-argument type-calls take 'str' as the first argument (#17168)
  Control flow: `return` and `raise` (#17121)
  Bump 0.11.3 (#17173)
  [red-knot] Improve `Debug` implementation for `semantic_index::SymbolTable` (#17172)
  [red-knot] Fix `str(…)` calls (#17163)
  [red-knot] visibility_constraint analysis for match cases (#17077)
  [red-knot] Fix playground crashes when diagnostics are stale (#17165)
  [red-knot] Callable types are disjoint from literals (#17160)
  [red-knot] Fix inference for `pow` between two literal integers (#17161)
  [red-knot] Add GitHub PR annotations when mdtests fail in CI (#17150)
  [red-knot] Fix equivalence of differently ordered unions that contain `Callable` types (#17145)
  [red-knot] Add initial set of tests for unreachable code (#17159)
  [`airflow`] Move `AIR302` to `AIR301` and `AIR303` to `AIR302` (#17151)
  ruff_db: simplify lifetimes on `DiagnosticDisplay`
  [red-knot] Detect division-by-zero in unions and intersections (#17157)
  [`airflow`] Add autofix infrastructure to `AIR302` name checks (#16965)
  [`flake8-bandit`] Mark `str` and `list[str]` literals as trusted input (`S603`) (#17136)
  [`airflow`] Add autofix for `AIR302` attribute checks (#16977)
  [`airflow`] Extend `AIR302` with additional symbols (#17085)
  ...
maxmynter pushed a commit to maxmynter/ruff that referenced this pull request Apr 3, 2025
…l-sh#17157)

## Summary

With this PR, we emit a diagnostic for this case where
previously didn't:
```py
from typing import Literal

def f(m: int, n: Literal[-1, 0, 1]):
    # error: [division-by-zero] "Cannot divide object of type `int` by zero"
    return m / n
```

## Test Plan

New Markdown test
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3 participants