python-linting syntax-checking ruff version-compatibility release

Ruff v0.12 detects syntax errors across Python versions

Ruff now catches version-specific syntax errors (match statements, walrus operators) and compiler-stage errors (duplicate parameters, yield outside functions) before runtime, replacing separate linting passes.

Summary

Syntax error detection moves left in the dev cycle—catch version incompatibilities and compiler errors during linting rather than test runs. Reduces friction for multi-version projects with per-file version targeting.

Why it matters

Implementation verdict

Drop-in upgrade for existing Ruff users. Breaking changes minimal; most projects upgrade without code changes. Requires explicit target-version configuration to leverage new syntax detection—defaults to Python 3.13 for syntax checking, 3.9 for other rules. Worth upgrading now if your CI already uses Ruff.

Sources

1.Ruff can be used to replace Black, Flake8 (plus dozens of plugins), isort, pydocstyle, pyupgrade, and more, all while executing tens or hundreds of times faster than any individual tool
2.Ruff's parser is now version-aware and will emit diagnostics if you use any syntax that is not available on your current Python version
3.In v0.12, Ruff has two separate defaults for these scenarios, when no Python version is configured: "latest" (3.13) when detecting syntax errors, and "oldest" (3.9) for everything else

Dev Signal

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