v0.21.0

Pyrefly 0.21.0

Status : ALPHA
Release date: 23 June 2025

Pyrefly 0.21.0 delivers 176 commits from 20 contributors. We now support a number of highly requested features such as Semantic Highlighting, Signature Help, Document Highlights and Auto Import Completions! Follow along for more LSP functionality #344 ahead of our V1 release.

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✨ New & Improved

Area	What’s new
IDE / LSP (Issue #344)	• Richer semantic highlighting – method calls, property accesses, and the expressions nested in them now get distinct token types, so editors like VS Code underline exactly what you expect (#344). • Added the defaultLibrary semantic-token modifier for symbols originating from builtins, typing, or typing_extensions; makes built-ins stand out in both dark/light themes.
Diagnostics	• Detailed override errors – incompatibilities between a subclass attribute and its parent now explain why they don’t match (“read-write vs read-only”, “int vs str”, etc.) on a second indented line.
Type-system smarts	• InitVar fields in @dataclass definitions are no longer treated as instance attributes, eliminating false “missing attribute” errors (PR [#437]). • Full support for Variance Inference in Generic Classes with PEP 695
Performance	• A pathological Callable | … union test that once blew up exponentially now checks in linear time.

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🐛 Other bug fixes

• Multiple edge-case panics removed, including starred targets inside augmented assignments and cyclic class-type substitutions.
• Hover & go-to-definition in LSP no longer crash when traversing keyword-only or pattern-match bindings.
• Cargo / Rust nightly warnings cleaned up; WASM build green again.

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🚨 Potentially breaking

• The new, more explicit override-mismatch diagnostics may fail code that relied on silent attribute-type changes.
• Editors that hard-code semantic-token kinds should be updated to recognise the new defaultLibrary modifier.

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📦 Upgrade

pip install --upgrade pyrefly==0.21.0

🖊️ Contributors this release

@yangdanny97 @Adist319 @grievejia @connernilsen @migeed-z @ndmitchell @xl4624 @stroxler @rchen152 @TheRustyPickle @dluo @kinto0 @pt2302 @SamChou19815 @ducdetronquito @xaskii @Alex-Aron @hugovk @grantlouisherman @rubmary

v0.20.0

Pyrefly 0.20.0

Status : ALPHA
Release date: 16 June 2025

Pyrefly 0.20.0 represents 165 commits from 21 contributors and focuses on stability, friendlier diagnostics, and CLI quality-of-life.

Special thanks to @TheRustyPickle, @ducdetronquito, @pt2302, @akmalsoliev and every reviewer, tester and bug-reporter who helped make this release!

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✨ New & Improved

Area	What’s new
Diagnostics & error messages	•We now print a snippet of source code in each message, highlighting the error location. You can control error message verbosity with the new --output-format=min-text and --output-format=full-text options. •Add tests to keep Error Kinds in sync with documentation, in addition to reclassifying Error Kinds previously reported as Unknown (#477). • Import errors are now shown on separate lines with source hints, thanks to the new BindingsBuilder::error_multiline helper (commit 2bba00f). •TypeVar reveal output is shorter and clearer – no more variance=PInvariant noise (#225).
Editor support	•Basic support for Semantic Highlighting, a highly requested feature (#218). More improvements to come in future releases.
Configuration / CLI	• New flags --replace-imports-with-any and --ignore-missing-source let you suppress noisy import errors without editing config files (#480 → closes #460 & #462).
Type-system smarts	• Conflicting Required/NotRequired qualifiers in a single TypedDict field now surface an explicit error (#447→ fixes #414).
Project workflow	• pyrefly init edits an existing pyproject.toml in-place instead of appending duplicate [tool.pyrefly] sections (#336).

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🐛 Other notable bug fixes

• Panics fixed:
  • Missing NoneType stub when running with --python-version 3.9 (#56).
  • Starred targets in augmented assignments no longer crash the checker (#468).
• Hover & go-to-definition no longer crash the LSP on keyword-only or pattern-match bindings.
• Build is quiet again on nightly Rust; cleaned up stray clippy warnings.

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🚨 Potentially breaking

• Flag & message renames – some diagnostics switched from snake-case to kebab-case and new CLI flags were introduced (#480). Update any scripts that parse pyrefly check --help or grep error kinds.
• The TypedDict qualifier rule (#447) may surface new errors where both Required and NotRequired were previously accepted.

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📦 Upgrade

pip install --upgrade pyrefly==0.20.0

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🖊️ Contributors in this release

@rchen152, @grievejia, @stroxler, @ajaymiranda, @connernilsen, @pt2302, @kinto0, @yangdanny97, @ndmitchell, @migeed-z, @hugovk, @dtolnay, @Alex-Aron, @Adist319, @zachmullen, @grantlouisherman, @rubmary, @dluo, @maggiemoss, @kinto0, @SamChou19815

v0.19.0

Pyrefly 0.19.0

Status : ALPHA

Release date: 9 June 2025

Pyrefly 0.19.0 packs a week’s worth of fixes and quality‑of‑life improvements into 128 commits from 19 contributors, touching 153 files.

Thank you @ajaymiranda @Adist319 @Alex-Aron @zachmullen for your contributions!

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✨ New & Improved

Area	What’s new
Editor support	• Neovim integration — first‑class LSP support plus a helper command to install/update the server (#227). • Neovim now respects pyrefly.toml and remote config overrides (#442).
Configuration UX	• Eliminates misleading “Extra keys” parse errors in pyrefly.toml (#441). • Added validation that a TypedDict field cannot be both Required and NotRequired (#414).
Diagnostics	• reveal_type messages are now INFO‑level instead of errors, so they no longer fail CI runs when you’re just inspecting types (#304). • isinstance() checks involving Union[...] are now inferred correctly (#426).
Type‑system smarts	• Better handling of Self generics in chained method calls (#152). • Fixed constrained TypeVar attribute access (#318). • Fixed failure when calling methods on a plain TypeVar (#150).
Stub & third‑party typing	• Works with inline stub files that live beside their implementation (#419). • Correctly recognises pandas-stubs generic aliases such as Index without type arguments (#427).

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🐛 Other notable bug fixes

• Duplicate “NoReturn / Never” return‑annotation error reduced to a single authoritative report (#425).
• Numerous minor LSP crashes and hover glitches fixed.
• Documentation on website and CLI cleanup

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🚨 Potentially breaking

• The new TypedDict qualifier rule (#414) will surface errors in code that previously passed silently.
• If you relied on reveal_type raising an error exit status, update scripts to look for an info‑level diagnostic instead (#304).

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📦 Upgrade

pip install --upgrade pyrefly==0.19.0

🖊️ Contributors in this release

@Adist319, @Alex-Aron, @connernilsen, @yangdanny97, @dluo , @dtolnay, @hugovk, @grantlouisherman, @grievejia, @kinto0, @maggiemoss, @ndmitchell, @rchen152, @rubmary, @SamChou19815, @stroxler, @migeed-z