v0.4.1

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Preview features

• [pylint] Implement invalid-hash-returned (PLE0309) (#​10961)
• [pylint] Implement invalid-index-returned (PLE0305) (#​10962)

Bug fixes

• [pylint] Allow NoReturn-like functions for __str__, __len__, etc. (PLE0307) (#​11017)
• Parser: Use empty range when there's "gap" in token source (#​11032)
• [ruff] Ignore stub functions in unused-async (RUF029) (#​11026)
• Parser: Expect indented case block instead of match stmt (#​11033)

v0.4.0

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A new, hand-written parser

Ruff's new parser is >2x faster, which translates to a 20-40% speedup for all linting and formatting invocations.
There's a lot to say about this exciting change, so check out the blog post for more details!

See #​10036 for implementation details.

A new language server in Rust

With this release, we also want to highlight our new language server. ruff server is a Rust-powered language
server that comes built-in with Ruff. It can be used with any editor that supports the Language Server Protocol (LSP).
It uses a multi-threaded, lock-free architecture inspired by rust-analyzer and it will open the door for a lot
of exciting features. It’s also faster than our previous Python-based language server
-- but you probably guessed that already.

ruff server is only in alpha, but it has a lot of features that you can try out today:

• Lints Python files automatically and shows quick-fixes when available
• Formats Python files, with support for range formatting
• Comes with commands for quickly performing actions: ruff.applyAutofix, ruff.applyFormat, and ruff.applyOrganizeImports
• Supports source.fixAll and source.organizeImports source actions
• Automatically reloads your project configuration when you change it

To setup ruff server with your editor, refer to the README.md.

Preview features

• [pycodestyle] Do not trigger E3 rules on defs following a function/method with a dummy body (#​10704)
• [pylint] Implement invalid-bytes-returned (E0308) (#​10959)
• [pylint] Implement invalid-length-returned (E0303) (#​10963)
• [pylint] Implement self-cls-assignment (W0642) (#​9267)
• [pylint] Omit stubs from invalid-bool and invalid-str-return-type (#​11008)
• [ruff] New rule unused-async (RUF029) to detect unneeded async keywords on functions (#​9966)

Rule changes

• [flake8-bandit] Allow urllib.request.urlopen calls with static Request argument (S310) (#​10964)
• [flake8-bugbear] Treat raise NotImplemented-only bodies as stub functions (B006) (#​10990)
• [flake8-slots] Respect same-file Enum subclasses (SLOT000) (#​11006)
• [pylint] Support inverted comparisons (PLR1730) (#​10920)

Linter

• Improve handling of builtin symbols in linter rules (#​10919)
• Improve display of rules in --show-settings (#​11003)
• Improve inference capabilities of the BuiltinTypeChecker (#​10976)
• Resolve classes and functions relative to script name (#​10965)
• Improve performance of RuleTable::any_enabled (#​10971)

Server

This section is devoted to updates for our new language server, written in Rust.

• Enable ruff-specific source actions (#​10916)
• Refreshes diagnostics for open files when file configuration is changed (#​10988)
• Important errors are now shown as popups (#​10951)
• Introduce settings for directly configuring the linter and formatter (#​10984)
• Resolve configuration for each document individually (#​10950)
• Write a setup guide for Neovim (#​10987)

Configuration

• Add RUFF_OUTPUT_FILE environment variable support (#​10992)

Bug fixes

• Avoid non-augmented-assignment for reversed, non-commutative operators (PLR6104) (#​10909)
• Limit commutative non-augmented-assignments to primitive data types (PLR6104) (#​10912)
• Respect per-file-ignores for RUF100 on blanket # noqa (#​10908)
• Consider if expression for parenthesized with items parsing (#​11010)
• Consider binary expr for parenthesized with items parsing (#​11012)
• Reset FOR_TARGET context for all kinds of parentheses (#​11009)