Bump version to 0.6.4 (#13253 )

[red-knot] fix lookup of nonlocal names in deferred annotations (#13236 )
Initially I had deferred annotation name lookups reuse the "public symbol type", since that gives the correct "from end of scope" view of reaching definitions that we want. But there is a key difference; public symbol types are based only on definitions in the queried scope (or "name in the given namespace" in runtime terms), they don't ever look up a name in nonlocal/global/builtin scopes. Deferred annotation resolution should do this lookup. Add a test, and fix deferred name resolution to support nonlocal/global/builtin names. Fixes #13176
2024-09-05 21:05:15 +05:30 · 2024-09-04 10:10:54 -07:00 · 2024-09-04 14:24:58 +00:00 · 2024-09-04 14:19:11 +00:00 · 2024-09-04 10:19:50 +00:00 · 2024-09-04 09:35:58 +00:00
305 changed files with 10326 additions and 2913 deletions
--- a/.devcontainer/devcontainer.json
+++ b/.devcontainer/devcontainer.json
@@ -20,7 +20,7 @@
 			"extensions": [
 				"ms-python.python",
 				"rust-lang.rust-analyzer",
-				"serayuzgur.crates",
+				"fill-labs.dependi",
 				"tamasfe.even-better-toml",
 				"Swellaby.vscode-rust-test-adapter",
 				"charliermarsh.ruff"
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -37,7 +37,7 @@ jobs:
        with:
          fetch-depth: 0

-      - uses: tj-actions/changed-files@v44
+      - uses: tj-actions/changed-files@v45
        id: changed
        with:
          files_yaml: |
--- a/.github/workflows/publish-docs.yml
+++ b/.github/workflows/publish-docs.yml
@@ -34,10 +34,10 @@ jobs:
      - name: "Set docs version"
        run: |
          version="${{ (inputs.plan != '' && fromJson(inputs.plan).announcement_tag) || inputs.ref }}"
-          # if version is missing, exit with error
-          if [[ -z "$version" ]]; then
-          echo "Can't build docs without a version."
-          exit 1
+          # if version is missing, use 'latest'
+          if [ -z "$version" ]; then
+            echo "Using 'latest' as version"
+            version="latest"
          fi

          # Use version as display name for now
@@ -145,6 +145,7 @@ jobs:
          GITHUB_TOKEN: ${{ secrets.ASTRAL_DOCS_PAT }}
        run: |
          branch_name="${{ env.branch_name }}"
+
          # auto-merge the PR if the build was triggered by a release. Manual builds should be reviewed by a human.
          # give the PR a few seconds to be created before trying to auto-merge it
          sleep 10
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -45,7 +45,7 @@ repos:
          )$

  - repo: https://github.com/crate-ci/typos
-    rev: v1.23.6
+    rev: v1.24.3
    hooks:
      - id: typos

@@ -59,7 +59,7 @@ repos:
        pass_filenames: false # This makes it a lot faster

  - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.6.1
+    rev: v0.6.3
    hooks:
      - id: ruff-format
      - id: ruff
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,90 @@
 # Changelog

+## 0.6.4
+
+### Preview features
+
+- \[`flake8-builtins`\] Use dynamic builtins list based on Python version ([#13172](https://github.com/astral-sh/ruff/pull/13172))
+- \[`pydoclint`\] Permit yielding `None` in `DOC402` and `DOC403` ([#13148](https://github.com/astral-sh/ruff/pull/13148))
+- \[`pylint`\] Update diagnostic message for `PLW3201` ([#13194](https://github.com/astral-sh/ruff/pull/13194))
+- \[`ruff`\] Implement `post-init-default` (`RUF033`) ([#13192](https://github.com/astral-sh/ruff/pull/13192))
+- \[`ruff`\] Implement useless if-else (`RUF034`) ([#13218](https://github.com/astral-sh/ruff/pull/13218))
+
+### Rule changes
+
+- \[`flake8-pyi`\] Respect `pep8_naming.classmethod-decorators` settings when determining if a method is a classmethod in `custom-type-var-return-type` (`PYI019`) ([#13162](https://github.com/astral-sh/ruff/pull/13162))
+- \[`flake8-pyi`\] Teach various rules that annotations might be stringized ([#12951](https://github.com/astral-sh/ruff/pull/12951))
+- \[`pylint`\] Avoid `no-self-use` for `attrs`-style validators ([#13166](https://github.com/astral-sh/ruff/pull/13166))
+- \[`pylint`\] Recurse into subscript subexpressions when searching for list/dict lookups (`PLR1733`, `PLR1736`) ([#13186](https://github.com/astral-sh/ruff/pull/13186))
+- \[`pyupgrade`\] Detect `aiofiles.open` calls in `UP015` ([#13173](https://github.com/astral-sh/ruff/pull/13173))
+- \[`pyupgrade`\] Mark `sys.version_info[0] < 3` and similar comparisons as outdated (`UP036`) ([#13175](https://github.com/astral-sh/ruff/pull/13175))
+
+### CLI
+
+- Enrich messages of SARIF results ([#13180](https://github.com/astral-sh/ruff/pull/13180))
+- Handle singular case for incompatible rules warning in `ruff format` output ([#13212](https://github.com/astral-sh/ruff/pull/13212))
+
+### Bug fixes
+
+- \[`pydocstyle`\] Improve heuristics for detecting Google-style docstrings ([#13142](https://github.com/astral-sh/ruff/pull/13142))
+- \[`refurb`\] Treat `sep` arguments with effects as unsafe removals (`FURB105`) ([#13165](https://github.com/astral-sh/ruff/pull/13165))
+
+## 0.6.3
+
+### Preview features
+
+- \[`flake8-simplify`\] Extend `open-file-with-context-handler` to work with `dbm.sqlite3` (`SIM115`) ([#13104](https://github.com/astral-sh/ruff/pull/13104))
+- \[`pycodestyle`\] Disable `E741` in stub files (`.pyi`) ([#13119](https://github.com/astral-sh/ruff/pull/13119))
+- \[`pydoclint`\] Avoid `DOC201` on explicit returns in functions that only return `None` ([#13064](https://github.com/astral-sh/ruff/pull/13064))
+
+### Rule changes
+
+- \[`flake8-async`\] Disable check for `asyncio` before Python 3.11 (`ASYNC109`) ([#13023](https://github.com/astral-sh/ruff/pull/13023))
+
+### Bug fixes
+
+- \[`FastAPI`\] Avoid introducing invalid syntax in fix for `fast-api-non-annotated-dependency` (`FAST002`) ([#13133](https://github.com/astral-sh/ruff/pull/13133))
+- \[`flake8-implicit-str-concat`\] Normalize octals before merging concatenated strings in `single-line-implicit-string-concatenation` (`ISC001`) ([#13118](https://github.com/astral-sh/ruff/pull/13118))
+- \[`flake8-pytest-style`\] Improve help message for `pytest-incorrect-mark-parentheses-style` (`PT023`) ([#13092](https://github.com/astral-sh/ruff/pull/13092))
+- \[`pylint`\] Avoid autofix for calls that aren't `min` or `max` as starred expression (`PLW3301`) ([#13089](https://github.com/astral-sh/ruff/pull/13089))
+- \[`ruff`\] Add `datetime.time`, `datetime.tzinfo`, and `datetime.timezone` as immutable function calls (`RUF009`) ([#13109](https://github.com/astral-sh/ruff/pull/13109))
+- \[`ruff`\] Extend comment deletion for `RUF100` to include trailing text from `noqa` directives while preserving any following comments on the same line, if any ([#13105](https://github.com/astral-sh/ruff/pull/13105))
+- Fix dark theme on initial page load for the Ruff playground ([#13077](https://github.com/astral-sh/ruff/pull/13077))
+
+## 0.6.2
+
+### Preview features
+
+- \[`flake8-simplify`\] Extend `open-file-with-context-handler` to work with other standard-library IO modules (`SIM115`) ([#12959](https://github.com/astral-sh/ruff/pull/12959))
+- \[`ruff`\] Avoid `unused-async` for functions with FastAPI route decorator (`RUF029`) ([#12938](https://github.com/astral-sh/ruff/pull/12938))
+- \[`ruff`\] Ignore `fstring-missing-syntax` (`RUF027`) for `fastAPI` paths ([#12939](https://github.com/astral-sh/ruff/pull/12939))
+- \[`ruff`\] Implement check for Decimal called with a float literal (RUF032) ([#12909](https://github.com/astral-sh/ruff/pull/12909))
+
+### Rule changes
+
+- \[`flake8-bugbear`\] Update diagnostic message when expression is at the end of function (`B015`) ([#12944](https://github.com/astral-sh/ruff/pull/12944))
+- \[`flake8-pyi`\] Skip type annotations in `string-or-bytes-too-long` (`PYI053`) ([#13002](https://github.com/astral-sh/ruff/pull/13002))
+- \[`flake8-type-checking`\] Always recognise relative imports as first-party ([#12994](https://github.com/astral-sh/ruff/pull/12994))
+- \[`flake8-unused-arguments`\] Ignore unused arguments on stub functions (`ARG001`) ([#12966](https://github.com/astral-sh/ruff/pull/12966))
+- \[`pylint`\] Ignore augmented assignment for `self-cls-assignment` (`PLW0642`) ([#12957](https://github.com/astral-sh/ruff/pull/12957))
+
+### Server
+
+- Show full context in error log messages ([#13029](https://github.com/astral-sh/ruff/pull/13029))
+
+### Bug fixes
+
+- \[`pep8-naming`\] Don't flag `from` imports following conventional import names (`N817`) ([#12946](https://github.com/astral-sh/ruff/pull/12946))
+- \[`pylint`\] - Allow `__new__` methods to have `cls` as their first argument even if decorated with `@staticmethod` for `bad-staticmethod-argument` (`PLW0211`) ([#12958](https://github.com/astral-sh/ruff/pull/12958))
+
+### Documentation
+
+- Add `hyperfine` installation instructions; update `hyperfine` code samples ([#13034](https://github.com/astral-sh/ruff/pull/13034))
+- Expand note to use Ruff with other language server in Kate ([#12806](https://github.com/astral-sh/ruff/pull/12806))
+- Update example for `PT001` as per the new default behavior ([#13019](https://github.com/astral-sh/ruff/pull/13019))
+- \[`perflint`\] Improve docs for `try-except-in-loop` (`PERF203`) ([#12947](https://github.com/astral-sh/ruff/pull/12947))
+- \[`pydocstyle`\] Add reference to `lint.pydocstyle.ignore-decorators` setting to rule docs ([#12996](https://github.com/astral-sh/ruff/pull/12996))
+
 ## 0.6.1

 This is a hotfix release to address an issue with `ruff-pre-commit`. In v0.6,
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -530,6 +530,8 @@ You can run the benchmarks with
 cargo benchmark
 ```

+`cargo benchmark` is an alias for `cargo bench -p ruff_benchmark --bench linter --bench formatter --`
+
 #### Benchmark-driven Development

 Ruff uses [Criterion.rs](https://bheisler.github.io/criterion.rs/book/) for benchmarks. You can use
@@ -568,7 +570,7 @@ cargo install critcmp

 #### Tips

- Use `cargo bench -p ruff_benchmark <filter>` to only run specific benchmarks. For example: `cargo benchmark lexer`
+- Use `cargo bench -p ruff_benchmark <filter>` to only run specific benchmarks. For example: `cargo bench -p ruff_benchmark lexer`
    to only run the lexer benchmarks.
 - Use `cargo bench -p ruff_benchmark -- --quiet` for a more cleaned up output (without statistical relevance)
 - Use `cargo bench -p ruff_benchmark -- --quick` to get faster results (more prone to noise)
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1256,9 +1256,9 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"

 [[package]]
 name = "libc"
-version = "0.2.157"
+version = "0.2.158"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "374af5f94e54fa97cf75e945cce8a6b201e88a1a07e688b47dfd2a59c66dbd86"
+checksum = "d8adc4bb1803a324070e64a98ae98f38934d91957a99cfb3a43dcbc01bc56439"

 [[package]]
 name = "libcst"
@@ -1803,9 +1803,9 @@ dependencies = [

 [[package]]
 name = "quick-junit"
-version = "0.4.0"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cfc1a6a5406a114913df2df8507998c755311b55b78584bed5f6e88f6417c4d4"
+checksum = "62ffd2f9a162cfae131bed6d9d1ed60adced33be340a94f96952897d7cb0c240"
 dependencies = [
 "chrono",
 "indexmap",
@@ -1818,18 +1818,18 @@ dependencies = [

 [[package]]
 name = "quick-xml"
-version = "0.31.0"
+version = "0.36.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1004a344b30a54e2ee58d66a71b32d2db2feb0a31f9a2d302bf0536f15de2a33"
+checksum = "96a05e2e8efddfa51a84ca47cec303fac86c8541b686d37cac5efc0e094417bc"
 dependencies = [
 "memchr",
 ]

 [[package]]
 name = "quote"
-version = "1.0.36"
+version = "1.0.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0fa76aaf39101c457836aec0ce2316dbdc3ab723cdda1c6bd4e6ad4208acaca7"
+checksum = "b5b9d34b8991d19d98081b46eacdd8eb58c6f2b201139f7c5f643cc155a633af"
 dependencies = [
 "proc-macro2",
 ]
@@ -1926,6 +1926,7 @@ dependencies = [
 "ruff_db",
 "ruff_index",
 "ruff_python_ast",
+ "ruff_python_literal",
 "ruff_python_parser",
 "ruff_python_stdlib",
 "ruff_source_file",
@@ -1988,6 +1989,7 @@ dependencies = [
 "anyhow",
 "crossbeam",
 "notify",
+ "rayon",
 "red_knot_python_semantic",
 "ruff_cache",
 "ruff_db",
@@ -1995,6 +1997,7 @@ dependencies = [
 "ruff_text_size",
 "rustc-hash 2.0.0",
 "salsa",
+ "tempfile",
 "tracing",
 ]

@@ -2088,7 +2091,7 @@ dependencies = [

 [[package]]
 name = "ruff"
-version = "0.6.1"
+version = "0.6.4"
 dependencies = [
 "anyhow",
 "argfile",
@@ -2146,6 +2149,7 @@ dependencies = [
 "criterion",
 "mimalloc",
 "once_cell",
+ "rayon",
 "red_knot_python_semantic",
 "red_knot_workspace",
 "ruff_db",
@@ -2280,7 +2284,7 @@ dependencies = [

 [[package]]
 name = "ruff_linter"
-version = "0.6.1"
+version = "0.6.4"
 dependencies = [
 "aho-corasick",
 "annotate-snippets 0.9.2",
@@ -2600,7 +2604,7 @@ dependencies = [

 [[package]]
 name = "ruff_wasm"
-version = "0.6.1"
+version = "0.6.4"
 dependencies = [
 "console_error_panic_hook",
 "console_log",
@@ -2827,9 +2831,9 @@ checksum = "1c107b6f4780854c8b126e228ea8869f4d7b71260f962fefb57b996b8959ba6b"

 [[package]]
 name = "serde"
-version = "1.0.208"
+version = "1.0.209"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cff085d2cb684faa248efb494c39b68e522822ac0de72ccf08109abde717cfb2"
+checksum = "99fce0ffe7310761ca6bf9faf5115afbc19688edd00171d81b1bb1b116c63e09"
 dependencies = [
 "serde_derive",
 ]
@@ -2847,9 +2851,9 @@ dependencies = [

 [[package]]
 name = "serde_derive"
-version = "1.0.208"
+version = "1.0.209"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "24008e81ff7613ed8e5ba0cfaf24e2c2f1e5b8a0495711e44fcd4882fca62bcf"
+checksum = "a5831b979fd7b5439637af1752d535ff49f4860c0f341d1baeb6faf0f4242170"
 dependencies = [
 "proc-macro2",
 "quote",
@@ -2869,9 +2873,9 @@ dependencies = [

 [[package]]
 name = "serde_json"
-version = "1.0.125"
+version = "1.0.127"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "83c8e735a073ccf5be70aa8066aa984eaf2fa000db6c8d0100ae605b366d31ed"
+checksum = "8043c06d9f82bd7271361ed64f415fe5e12a77fdb52e573e7f06a516dea329ad"
 dependencies = [
 "itoa",
 "memchr",
@@ -3030,9 +3034,9 @@ checksum = "81cdd64d312baedb58e21336b31bc043b77e01cc99033ce76ef539f78e965ebc"

 [[package]]
 name = "syn"
-version = "2.0.75"
+version = "2.0.76"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f6af063034fc1935ede7be0122941bafa9bacb949334d090b77ca98b5817c7d9"
+checksum = "578e081a14e0cefc3279b0472138c513f37b41a08d5a3cca9b6e4e8ceb6cd525"
 dependencies = [
 "proc-macro2",
 "quote",
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -102,7 +102,7 @@ pep440_rs = { version = "0.6.0", features = ["serde"] }
 pretty_assertions = "1.3.0"
 proc-macro2 = { version = "1.0.79" }
 pyproject-toml = { version = "0.9.0" }
-quick-junit = { version = "0.4.0" }
+quick-junit = { version = "0.5.0" }
 quote = { version = "1.0.23" }
 rand = { version = "0.8.5" }
 rayon = { version = "1.10.0" }
--- a/README.md
+++ b/README.md
@@ -110,7 +110,7 @@ For more, see the [documentation](https://docs.astral.sh/ruff/).
 1. [Who's Using Ruff?](#whos-using-ruff)
 1. [License](#license)

-## Getting Started
+## Getting Started<a id="getting-started"></a>

 For more, see the [documentation](https://docs.astral.sh/ruff/).

@@ -136,8 +136,8 @@ curl -LsSf https://astral.sh/ruff/install.sh | sh
 powershell -c "irm https://astral.sh/ruff/install.ps1 | iex"

 # For a specific version.
-curl -LsSf https://astral.sh/ruff/0.6.1/install.sh | sh
-powershell -c "irm https://astral.sh/ruff/0.6.1/install.ps1 | iex"
+curl -LsSf https://astral.sh/ruff/0.6.4/install.sh | sh
+powershell -c "irm https://astral.sh/ruff/0.6.4/install.ps1 | iex"
 ```

 You can also install Ruff via [Homebrew](https://formulae.brew.sh/formula/ruff), [Conda](https://anaconda.org/conda-forge/ruff),
@@ -170,7 +170,7 @@ Ruff can also be used as a [pre-commit](https://pre-commit.com/) hook via [`ruff
 ```yaml
 - repo: https://github.com/astral-sh/ruff-pre-commit
  # Ruff version.
-  rev: v0.6.1
+  rev: v0.6.4
  hooks:
    # Run the linter.
    - id: ruff
@@ -195,7 +195,7 @@ jobs:
      - uses: chartboost/ruff-action@v1
 ```

-### Configuration
+### Configuration<a id="configuration"></a>

 Ruff can be configured through a `pyproject.toml`, `ruff.toml`, or `.ruff.toml` file (see:
 [_Configuration_](https://docs.astral.sh/ruff/configuration/), or [_Settings_](https://docs.astral.sh/ruff/settings/)
@@ -291,7 +291,7 @@ features that may change prior to stabilization.
 See `ruff help` for more on Ruff's top-level commands, or `ruff help check` and `ruff help format`
 for more on the linting and formatting commands, respectively.

-## Rules
+## Rules<a id="rules"></a>

 <!-- Begin section: Rules -->

@@ -367,21 +367,21 @@ quality tools, including:

 For a complete enumeration of the supported rules, see [_Rules_](https://docs.astral.sh/ruff/rules/).

-## Contributing
+## Contributing<a id="contributing"></a>

 Contributions are welcome and highly appreciated. To get started, check out the
 [**contributing guidelines**](https://docs.astral.sh/ruff/contributing/).

 You can also join us on [**Discord**](https://discord.com/invite/astral-sh).

-## Support
+## Support<a id="support"></a>

 Having trouble? Check out the existing issues on [**GitHub**](https://github.com/astral-sh/ruff/issues),
 or feel free to [**open a new one**](https://github.com/astral-sh/ruff/issues/new).

 You can also ask for help on [**Discord**](https://discord.com/invite/astral-sh).

-## Acknowledgements
+## Acknowledgements<a id="acknowledgements"></a>

 Ruff's linter draws on both the APIs and implementation details of many other
 tools in the Python ecosystem, especially [Flake8](https://github.com/PyCQA/flake8), [Pyflakes](https://github.com/PyCQA/pyflakes),
@@ -405,7 +405,7 @@ Ruff is the beneficiary of a large number of [contributors](https://github.com/a

 Ruff is released under the MIT license.

-## Who's Using Ruff?
+## Who's Using Ruff?<a id="whos-using-ruff"></a>

 Ruff is used by a number of major open-source projects and companies, including:

@@ -524,7 +524,7 @@ If you're using Ruff, consider adding the Ruff badge to your project's `README.m
 <a href="https://github.com/astral-sh/ruff"><img src="https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/astral-sh/ruff/main/assets/badge/v2.json" alt="Ruff" style="max-width:100%;"></a>
 ```

-## License
+## License<a id="license"></a>

 This repository is licensed under the [MIT License](https://github.com/astral-sh/ruff/blob/main/LICENSE)

--- a/crates/red_knot/docs/tracing.md
+++ b/crates/red_knot/docs/tracing.md
@@ -13,12 +13,17 @@ The CLI supports different verbosity levels.
 - `-vv` activates `debug!` and timestamps: This should be enough information to get to the bottom of bug reports. When you're processing many packages or files, you'll get pages and pages of output, but each line is link to a specific action or state change.
 - `-vvv` activates `trace!` (only in debug builds) and shows tracing-spans: At this level, you're logging everything. Most of this is wasted, it's really slow, we dump e.g. the entire resolution graph. Only useful to developers, and you almost certainly want to use `RED_KNOT_LOG` to filter it down to the area your investigating.

-## `RED_KNOT_LOG`
+## Better logging with `RED_KNOT_LOG` and `RAYON_NUM_THREADS`

 By default, the CLI shows messages from the `ruff` and `red_knot` crates. Tracing messages from other crates are not shown.
 The `RED_KNOT_LOG` environment variable allows you to customize which messages are shown by specifying one
 or more [filter directives](https://docs.rs/tracing-subscriber/latest/tracing_subscriber/filter/struct.EnvFilter.html#directives).

+The `RAYON_NUM_THREADS` environment variable, meanwhile, can be used to control the level of concurrency red-knot uses.
+By default, red-knot will attempt to parallelize its work so that multiple files are checked simultaneously,
+but this can result in a confused logging output where messages from different threads are intertwined.
+To switch off concurrency entirely and have more readable logs, use `RAYON_NUM_THREADS=1`.
+
 ### Examples

 #### Show all debug messages
--- a/crates/red_knot_python_semantic/Cargo.toml
+++ b/crates/red_knot_python_semantic/Cargo.toml
@@ -17,6 +17,7 @@ ruff_python_ast = { workspace = true }
 ruff_python_stdlib = { workspace = true }
 ruff_source_file = { workspace = true }
 ruff_text_size = { workspace = true }
+ruff_python_literal = { workspace = true }

 anyhow = { workspace = true }
 bitflags = { workspace = true }
--- a/crates/red_knot_python_semantic/src/ast_node_ref.rs
+++ b/crates/red_knot_python_semantic/src/ast_node_ref.rs
@@ -31,10 +31,10 @@ impl<T> AstNodeRef<T> {
    /// which the `AstNodeRef` belongs.
    ///
    /// ## Safety
+    ///
    /// Dereferencing the `node` can result in undefined behavior if `parsed` isn't the
    /// [`ParsedModule`] to which `node` belongs. It's the caller's responsibility to ensure that
    /// the invariant `node belongs to parsed` is upheld.
-
    pub(super) unsafe fn new(parsed: ParsedModule, node: &T) -> Self {
        Self {
            _parsed: parsed,
--- a/crates/red_knot_python_semantic/src/builtins.rs
+++ b/crates/red_knot_python_semantic/src/builtins.rs
@@ -1,16 +0,0 @@
-use crate::module_name::ModuleName;
-use crate::module_resolver::resolve_module;
-use crate::semantic_index::global_scope;
-use crate::semantic_index::symbol::ScopeId;
-use crate::Db;
-
-/// Salsa query to get the builtins scope.
-///
-/// Can return None if a custom typeshed is used that is missing `builtins.pyi`.
-#[salsa::tracked]
-pub(crate) fn builtins_scope(db: &dyn Db) -> Option<ScopeId<'_>> {
-    let builtins_name =
-        ModuleName::new_static("builtins").expect("Expected 'builtins' to be a valid module name");
-    let builtins_file = resolve_module(db, builtins_name)?.file();
-    Some(global_scope(db, builtins_file))
-}
--- a/crates/red_knot_python_semantic/src/lib.rs
+++ b/crates/red_knot_python_semantic/src/lib.rs
@@ -10,7 +10,6 @@ pub use python_version::PythonVersion;
 pub use semantic_model::{HasTy, SemanticModel};

 pub mod ast_node_ref;
-mod builtins;
 mod db;
 mod module_name;
 mod module_resolver;
@@ -20,6 +19,8 @@ mod python_version;
 pub mod semantic_index;
 mod semantic_model;
 pub(crate) mod site_packages;
+mod stdlib;
 pub mod types;

 type FxOrderSet<V> = ordermap::set::OrderSet<V, BuildHasherDefault<FxHasher>>;
+type FxOrderMap<K, V> = ordermap::map::OrderMap<K, V, BuildHasherDefault<FxHasher>>;
--- a/crates/red_knot_python_semantic/src/semantic_index.rs
+++ b/crates/red_knot_python_semantic/src/semantic_index.rs
@@ -575,7 +575,7 @@ def f(a: str, /, b: str, c: int = 1, *args, d: int = 2, **kwargs):
        let index = semantic_index(&db, file);
        let global_table = symbol_table(&db, global_scope(&db, file));

-        assert_eq!(names(&global_table), vec!["f", "str", "int"]);
+        assert_eq!(names(&global_table), vec!["str", "int", "f"]);

        let [(function_scope_id, _function_scope)] = index
            .child_scopes(FileScopeId::global())
@@ -666,7 +666,7 @@ def f(a: str, /, b: str, c: int = 1, *args, d: int = 2, **kwargs):
    fn comprehension_scope() {
        let TestCase { db, file } = test_case(
            "
-[x for x in iter1]
+[x for x, y in iter1]
 ",
        );

@@ -690,7 +690,22 @@ def f(a: str, /, b: str, c: int = 1, *args, d: int = 2, **kwargs):

        let comprehension_symbol_table = index.symbol_table(comprehension_scope_id);

-        assert_eq!(names(&comprehension_symbol_table), vec!["x"]);
+        assert_eq!(names(&comprehension_symbol_table), vec!["x", "y"]);
+
+        let use_def = index.use_def_map(comprehension_scope_id);
+        for name in ["x", "y"] {
+            let definition = use_def
+                .first_public_definition(
+                    comprehension_symbol_table
+                        .symbol_id_by_name(name)
+                        .expect("symbol exists"),
+                )
+                .unwrap();
+            assert!(matches!(
+                definition.node(&db),
+                DefinitionKind::Comprehension(_)
+            ));
+        }
    }

    /// Test case to validate that the `x` variable used in the comprehension is referencing the
@@ -730,8 +745,8 @@ def f(a: str, /, b: str, c: int = 1, *args, d: int = 2, **kwargs):
        let DefinitionKind::Comprehension(comprehension) = definition.node(&db) else {
            panic!("expected generator definition")
        };
-        let ast::Comprehension { target, .. } = comprehension.node();
-        let name = target.as_name_expr().unwrap().id().as_str();
+        let target = comprehension.target();
+        let name = target.id().as_str();

        assert_eq!(name, "x");
        assert_eq!(target.range(), TextRange::new(23.into(), 24.into()));
@@ -1073,7 +1088,7 @@ def x():
    }

    #[test]
-    fn match_stmt_symbols() {
+    fn match_stmt() {
        let TestCase { db, file } = test_case(
            "
 match subject:
@@ -1087,12 +1102,124 @@ match subject:
 ",
        );

-        let global_table = symbol_table(&db, global_scope(&db, file));
+        let global_scope_id = global_scope(&db, file);
+        let global_table = symbol_table(&db, global_scope_id);

        assert!(global_table.symbol_by_name("Foo").unwrap().is_used());
        assert_eq!(
            names(&global_table),
-            vec!["subject", "a", "b", "c", "d", "f", "e", "h", "g", "Foo", "i", "j", "k", "l"]
+            vec!["subject", "a", "b", "c", "d", "e", "f", "g", "h", "Foo", "i", "j", "k", "l"]
        );
+
+        let use_def = use_def_map(&db, global_scope_id);
+        for (name, expected_index) in [
+            ("a", 0),
+            ("b", 0),
+            ("c", 1),
+            ("d", 2),
+            ("e", 0),
+            ("f", 1),
+            ("g", 0),
+            ("h", 1),
+            ("i", 0),
+            ("j", 1),
+            ("k", 0),
+            ("l", 1),
+        ] {
+            let definition = use_def
+                .first_public_definition(
+                    global_table.symbol_id_by_name(name).expect("symbol exists"),
+                )
+                .expect("Expected with item definition for {name}");
+            if let DefinitionKind::MatchPattern(pattern) = definition.node(&db) {
+                assert_eq!(pattern.index(), expected_index);
+            } else {
+                panic!("Expected match pattern definition for {name}");
+            }
+        }
+    }
+
+    #[test]
+    fn nested_match_case() {
+        let TestCase { db, file } = test_case(
+            "
+match 1:
+    case first:
+        match 2:
+            case second:
+                pass
+",
+        );
+
+        let global_scope_id = global_scope(&db, file);
+        let global_table = symbol_table(&db, global_scope_id);
+
+        assert_eq!(names(&global_table), vec!["first", "second"]);
+
+        let use_def = use_def_map(&db, global_scope_id);
+        for (name, expected_index) in [("first", 0), ("second", 0)] {
+            let definition = use_def
+                .first_public_definition(
+                    global_table.symbol_id_by_name(name).expect("symbol exists"),
+                )
+                .expect("Expected with item definition for {name}");
+            if let DefinitionKind::MatchPattern(pattern) = definition.node(&db) {
+                assert_eq!(pattern.index(), expected_index);
+            } else {
+                panic!("Expected match pattern definition for {name}");
+            }
+        }
+    }
+
+    #[test]
+    fn for_loops_single_assignment() {
+        let TestCase { db, file } = test_case("for x in a: pass");
+        let scope = global_scope(&db, file);
+        let global_table = symbol_table(&db, scope);
+
+        assert_eq!(&names(&global_table), &["a", "x"]);
+
+        let use_def = use_def_map(&db, scope);
+        let definition = use_def
+            .first_public_definition(global_table.symbol_id_by_name("x").unwrap())
+            .unwrap();
+
+        assert!(matches!(definition.node(&db), DefinitionKind::For(_)));
+    }
+
+    #[test]
+    fn for_loops_simple_unpacking() {
+        let TestCase { db, file } = test_case("for (x, y) in a: pass");
+        let scope = global_scope(&db, file);
+        let global_table = symbol_table(&db, scope);
+
+        assert_eq!(&names(&global_table), &["a", "x", "y"]);
+
+        let use_def = use_def_map(&db, scope);
+        let x_definition = use_def
+            .first_public_definition(global_table.symbol_id_by_name("x").unwrap())
+            .unwrap();
+        let y_definition = use_def
+            .first_public_definition(global_table.symbol_id_by_name("y").unwrap())
+            .unwrap();
+
+        assert!(matches!(x_definition.node(&db), DefinitionKind::For(_)));
+        assert!(matches!(y_definition.node(&db), DefinitionKind::For(_)));
+    }
+
+    #[test]
+    fn for_loops_complex_unpacking() {
+        let TestCase { db, file } = test_case("for [((a,) b), (c, d)] in e: pass");
+        let scope = global_scope(&db, file);
+        let global_table = symbol_table(&db, scope);
+
+        assert_eq!(&names(&global_table), &["e", "a", "b", "c", "d"]);
+
+        let use_def = use_def_map(&db, scope);
+        let definition = use_def
+            .first_public_definition(global_table.symbol_id_by_name("a").unwrap())
+            .unwrap();
+
+        assert!(matches!(definition.node(&db), DefinitionKind::For(_)));
    }
 }
--- a/crates/red_knot_python_semantic/src/semantic_index/builder.rs
+++ b/crates/red_knot_python_semantic/src/semantic_index/builder.rs
@@ -15,7 +15,7 @@ use crate::semantic_index::ast_ids::node_key::ExpressionNodeKey;
 use crate::semantic_index::ast_ids::AstIdsBuilder;
 use crate::semantic_index::definition::{
    AssignmentDefinitionNodeRef, ComprehensionDefinitionNodeRef, Definition, DefinitionNodeKey,
-    DefinitionNodeRef, ImportFromDefinitionNodeRef,
+    DefinitionNodeRef, ForStmtDefinitionNodeRef, ImportFromDefinitionNodeRef,
 };
 use crate::semantic_index::expression::Expression;
 use crate::semantic_index::symbol::{
@@ -26,7 +26,7 @@ use crate::semantic_index::use_def::{FlowSnapshot, UseDefMapBuilder};
 use crate::semantic_index::SemanticIndex;
 use crate::Db;

-use super::definition::WithItemDefinitionNodeRef;
+use super::definition::{MatchPatternDefinitionNodeRef, WithItemDefinitionNodeRef};

 pub(super) struct SemanticIndexBuilder<'db> {
    // Builder state
@@ -36,6 +36,8 @@ pub(super) struct SemanticIndexBuilder<'db> {
    scope_stack: Vec<FileScopeId>,
    /// The assignment we're currently visiting.
    current_assignment: Option<CurrentAssignment<'db>>,
+    /// The match case we're currently visiting.
+    current_match_case: Option<CurrentMatchCase<'db>>,
    /// Flow states at each `break` in the current loop.
    loop_break_states: Vec<FlowSnapshot>,

@@ -59,6 +61,7 @@ impl<'db> SemanticIndexBuilder<'db> {
            module: parsed,
            scope_stack: Vec::new(),
            current_assignment: None,
+            current_match_case: None,
            loop_break_states: vec![],

            scopes: IndexVec::new(),
@@ -190,8 +193,11 @@ impl<'db> SemanticIndexBuilder<'db> {
            countme::Count::default(),
        );

-        self.definitions_by_node
+        let existing_definition = self
+            .definitions_by_node
            .insert(definition_node.key(), definition);
+        debug_assert_eq!(existing_definition, None);
+
        self.current_use_def_map_mut()
            .record_definition(symbol, definition);

@@ -282,6 +288,7 @@ impl<'db> SemanticIndexBuilder<'db> {

        // The `iter` of the first generator is evaluated in the outer scope, while all subsequent
        // nodes are evaluated in the inner scope.
+        self.add_standalone_expression(&generator.iter);
        self.visit_expr(&generator.iter);
        self.push_scope(scope);

@@ -297,6 +304,7 @@ impl<'db> SemanticIndexBuilder<'db> {
        }

        for generator in generators_iter {
+            self.add_standalone_expression(&generator.iter);
            self.visit_expr(&generator.iter);

            self.current_assignment = Some(CurrentAssignment::Comprehension {
@@ -322,10 +330,11 @@ impl<'db> SemanticIndexBuilder<'db> {
            // Insert a mapping from the parameter to the same definition.
            // This ensures that calling `HasTy::ty` on the inner parameter returns
            // a valid type (and doesn't panic)
-            self.definitions_by_node.insert(
+            let existing_definition = self.definitions_by_node.insert(
                DefinitionNodeRef::from(AnyParameterRef::Variadic(&with_default.parameter)).key(),
                definition,
            );
+            debug_assert_eq!(existing_definition, None);
        }
    }

@@ -392,20 +401,6 @@ where
                    self.visit_decorator(decorator);
                }

-                let symbol = self
-                    .add_or_update_symbol(function_def.name.id.clone(), SymbolFlags::IS_DEFINED);
-                self.add_definition(symbol, function_def);
-
-                // The default value of the parameters needs to be evaluated in the
-                // enclosing scope.
-                for default in function_def
-                    .parameters
-                    .iter_non_variadic_params()
-                    .filter_map(|param| param.default.as_deref())
-                {
-                    self.visit_expr(default);
-                }
-
                self.with_type_params(
                    NodeWithScopeRef::FunctionTypeParameters(function_def),
                    function_def.type_params.as_deref(),
@@ -426,6 +421,21 @@ where
                        builder.pop_scope()
                    },
                );
+                // The default value of the parameters needs to be evaluated in the
+                // enclosing scope.
+                for default in function_def
+                    .parameters
+                    .iter_non_variadic_params()
+                    .filter_map(|param| param.default.as_deref())
+                {
+                    self.visit_expr(default);
+                }
+                // The symbol for the function name itself has to be evaluated
+                // at the end to match the runtime evaluation of parameter defaults
+                // and return-type annotations.
+                let symbol = self
+                    .add_or_update_symbol(function_def.name.id.clone(), SymbolFlags::IS_DEFINED);
+                self.add_definition(symbol, function_def);
            }
            ast::Stmt::ClassDef(class) => {
                for decorator in &class.decorator_list {
@@ -578,6 +588,38 @@ where
            ast::Stmt::Break(_) => {
                self.loop_break_states.push(self.flow_snapshot());
            }
+
+            ast::Stmt::For(
+                for_stmt @ ast::StmtFor {
+                    range: _,
+                    is_async: _,
+                    target,
+                    iter,
+                    body,
+                    orelse,
+                },
+            ) => {
+                // TODO add control flow similar to `ast::Stmt::While` above
+                self.add_standalone_expression(iter);
+                self.visit_expr(iter);
+                debug_assert!(self.current_assignment.is_none());
+                self.current_assignment = Some(for_stmt.into());
+                self.visit_expr(target);
+                self.current_assignment = None;
+                self.visit_body(body);
+                self.visit_body(orelse);
+            }
+            ast::Stmt::Match(ast::StmtMatch {
+                subject,
+                cases,
+                range: _,
+            }) => {
+                self.add_standalone_expression(subject);
+                self.visit_expr(subject);
+                for case in cases {
+                    self.visit_match_case(case);
+                }
+            }
            _ => {
                walk_stmt(self, stmt);
            }
@@ -624,6 +666,16 @@ where
                        Some(CurrentAssignment::AugAssign(aug_assign)) => {
                            self.add_definition(symbol, aug_assign);
                        }
+                        Some(CurrentAssignment::For(node)) => {
+                            self.add_definition(
+                                symbol,
+                                ForStmtDefinitionNodeRef {
+                                    iterable: &node.iter,
+                                    target: name_node,
+                                    is_async: node.is_async,
+                                },
+                            );
+                        }
                        Some(CurrentAssignment::Named(named)) => {
                            // TODO(dhruvmanila): If the current scope is a comprehension, then the
                            // named expression is implicitly nonlocal. This is yet to be
@@ -633,7 +685,11 @@ where
                        Some(CurrentAssignment::Comprehension { node, first }) => {
                            self.add_definition(
                                symbol,
-                                ComprehensionDefinitionNodeRef { node, first },
+                                ComprehensionDefinitionNodeRef {
+                                    iterable: &node.iter,
+                                    target: name_node,
+                                    first,
+                                },
                            );
                        }
                        Some(CurrentAssignment::WithItem(with_item)) => {
@@ -658,11 +714,11 @@ where
            }
            ast::Expr::Named(node) => {
                debug_assert!(self.current_assignment.is_none());
-                self.current_assignment = Some(node.into());
                // TODO walrus in comprehensions is implicitly nonlocal
+                self.visit_expr(&node.value);
+                self.current_assignment = Some(node.into());
                self.visit_expr(&node.target);
                self.current_assignment = None;
-                self.visit_expr(&node.value);
            }
            ast::Expr::Lambda(lambda) => {
                if let Some(parameters) = &lambda.parameters {
@@ -763,7 +819,7 @@ where
        }
    }

-    fn visit_parameters(&mut self, parameters: &'ast ruff_python_ast::Parameters) {
+    fn visit_parameters(&mut self, parameters: &'ast ast::Parameters) {
        // Intentionally avoid walking default expressions, as we handle them in the enclosing
        // scope.
        for parameter in parameters.iter().map(ast::AnyParameterRef::as_parameter) {
@@ -771,23 +827,58 @@ where
        }
    }

+    fn visit_match_case(&mut self, match_case: &'ast ast::MatchCase) {
+        debug_assert!(self.current_match_case.is_none());
+        self.current_match_case = Some(CurrentMatchCase::new(&match_case.pattern));
+        self.visit_pattern(&match_case.pattern);
+        self.current_match_case = None;
+
+        if let Some(expr) = &match_case.guard {
+            self.visit_expr(expr);
+        }
+        self.visit_body(&match_case.body);
+    }
+
    fn visit_pattern(&mut self, pattern: &'ast ast::Pattern) {
-        if let ast::Pattern::MatchAs(ast::PatternMatchAs {
-            name: Some(name), ..
-        })
-        | ast::Pattern::MatchStar(ast::PatternMatchStar {
+        if let ast::Pattern::MatchStar(ast::PatternMatchStar {
            name: Some(name),
            range: _,
+        }) = pattern
+        {
+            let symbol = self.add_or_update_symbol(name.id().clone(), SymbolFlags::IS_DEFINED);
+            let state = self.current_match_case.as_ref().unwrap();
+            self.add_definition(
+                symbol,
+                MatchPatternDefinitionNodeRef {
+                    pattern: state.pattern,
+                    identifier: name,
+                    index: state.index,
+                },
+            );
+        }
+
+        walk_pattern(self, pattern);
+
+        if let ast::Pattern::MatchAs(ast::PatternMatchAs {
+            name: Some(name), ..
        })
        | ast::Pattern::MatchMapping(ast::PatternMatchMapping {
            rest: Some(name), ..
        }) = pattern
        {
-            // TODO(dhruvmanila): Add definition
-            self.add_or_update_symbol(name.id.clone(), SymbolFlags::IS_DEFINED);
+            let symbol = self.add_or_update_symbol(name.id().clone(), SymbolFlags::IS_DEFINED);
+            let state = self.current_match_case.as_ref().unwrap();
+            self.add_definition(
+                symbol,
+                MatchPatternDefinitionNodeRef {
+                    pattern: state.pattern,
+                    identifier: name,
+                    index: state.index,
+                },
+            );
        }

-        walk_pattern(self, pattern);
+        self.current_match_case.as_mut().unwrap().index += 1;
    }
 }

@@ -796,6 +887,7 @@ enum CurrentAssignment<'a> {
    Assign(&'a ast::StmtAssign),
    AnnAssign(&'a ast::StmtAnnAssign),
    AugAssign(&'a ast::StmtAugAssign),
+    For(&'a ast::StmtFor),
    Named(&'a ast::ExprNamed),
    Comprehension {
        node: &'a ast::Comprehension,
@@ -822,6 +914,12 @@ impl<'a> From<&'a ast::StmtAugAssign> for CurrentAssignment<'a> {
    }
 }

+impl<'a> From<&'a ast::StmtFor> for CurrentAssignment<'a> {
+    fn from(value: &'a ast::StmtFor) -> Self {
+        Self::For(value)
+    }
+}
+
 impl<'a> From<&'a ast::ExprNamed> for CurrentAssignment<'a> {
    fn from(value: &'a ast::ExprNamed) -> Self {
        Self::Named(value)
@@ -833,3 +931,27 @@ impl<'a> From<&'a ast::WithItem> for CurrentAssignment<'a> {
        Self::WithItem(value)
    }
 }
+
+struct CurrentMatchCase<'a> {
+    /// The pattern that's part of the current match case.
+    pattern: &'a ast::Pattern,
+
+    /// The index of the sub-pattern that's being currently visited within the pattern.
+    ///
+    /// For example:
+    /// ```py
+    /// match subject:
+    ///     case a as b: ...
+    ///     case [a, b]: ...
+    ///     case a | b: ...
+    /// ```
+    ///
+    /// In all of the above cases, the index would be 0 for `a` and 1 for `b`.
+    index: u32,
+}
+
+impl<'a> CurrentMatchCase<'a> {
+    fn new(pattern: &'a ast::Pattern) -> Self {
+        Self { pattern, index: 0 }
+    }
+}
--- a/crates/red_knot_python_semantic/src/semantic_index/definition.rs
+++ b/crates/red_knot_python_semantic/src/semantic_index/definition.rs
@@ -39,6 +39,7 @@ impl<'db> Definition<'db> {
 pub(crate) enum DefinitionNodeRef<'a> {
    Import(&'a ast::Alias),
    ImportFrom(ImportFromDefinitionNodeRef<'a>),
+    For(ForStmtDefinitionNodeRef<'a>),
    Function(&'a ast::StmtFunctionDef),
    Class(&'a ast::StmtClassDef),
    NamedExpression(&'a ast::ExprNamed),
@@ -48,6 +49,7 @@ pub(crate) enum DefinitionNodeRef<'a> {
    Comprehension(ComprehensionDefinitionNodeRef<'a>),
    Parameter(ast::AnyParameterRef<'a>),
    WithItem(WithItemDefinitionNodeRef<'a>),
+    MatchPattern(MatchPatternDefinitionNodeRef<'a>),
 }

 impl<'a> From<&'a ast::StmtFunctionDef> for DefinitionNodeRef<'a> {
@@ -92,6 +94,12 @@ impl<'a> From<ImportFromDefinitionNodeRef<'a>> for DefinitionNodeRef<'a> {
    }
 }

+impl<'a> From<ForStmtDefinitionNodeRef<'a>> for DefinitionNodeRef<'a> {
+    fn from(value: ForStmtDefinitionNodeRef<'a>) -> Self {
+        Self::For(value)
+    }
+}
+
 impl<'a> From<AssignmentDefinitionNodeRef<'a>> for DefinitionNodeRef<'a> {
    fn from(node_ref: AssignmentDefinitionNodeRef<'a>) -> Self {
        Self::Assignment(node_ref)
@@ -116,6 +124,12 @@ impl<'a> From<ast::AnyParameterRef<'a>> for DefinitionNodeRef<'a> {
    }
 }

+impl<'a> From<MatchPatternDefinitionNodeRef<'a>> for DefinitionNodeRef<'a> {
+    fn from(node: MatchPatternDefinitionNodeRef<'a>) -> Self {
+        Self::MatchPattern(node)
+    }
+}
+
 #[derive(Copy, Clone, Debug)]
 pub(crate) struct ImportFromDefinitionNodeRef<'a> {
    pub(crate) node: &'a ast::StmtImportFrom,
@@ -134,12 +148,31 @@ pub(crate) struct WithItemDefinitionNodeRef<'a> {
    pub(crate) target: &'a ast::ExprName,
 }

+#[derive(Copy, Clone, Debug)]
+pub(crate) struct ForStmtDefinitionNodeRef<'a> {
+    pub(crate) iterable: &'a ast::Expr,
+    pub(crate) target: &'a ast::ExprName,
+    pub(crate) is_async: bool,
+}
+
 #[derive(Copy, Clone, Debug)]
 pub(crate) struct ComprehensionDefinitionNodeRef<'a> {
-    pub(crate) node: &'a ast::Comprehension,
+    pub(crate) iterable: &'a ast::Expr,
+    pub(crate) target: &'a ast::ExprName,
    pub(crate) first: bool,
 }

+#[derive(Copy, Clone, Debug)]
+pub(crate) struct MatchPatternDefinitionNodeRef<'a> {
+    /// The outermost pattern node in which the identifier being defined occurs.
+    pub(crate) pattern: &'a ast::Pattern,
+    /// The identifier being defined.
+    pub(crate) identifier: &'a ast::Identifier,
+    /// The index of the identifier in the pattern when visiting the `pattern` node in evaluation
+    /// order.
+    pub(crate) index: u32,
+}
+
 impl DefinitionNodeRef<'_> {
    #[allow(unsafe_code)]
    pub(super) unsafe fn into_owned(self, parsed: ParsedModule) -> DefinitionKind {
@@ -174,12 +207,24 @@ impl DefinitionNodeRef<'_> {
            DefinitionNodeRef::AugmentedAssignment(augmented_assignment) => {
                DefinitionKind::AugmentedAssignment(AstNodeRef::new(parsed, augmented_assignment))
            }
-            DefinitionNodeRef::Comprehension(ComprehensionDefinitionNodeRef { node, first }) => {
-                DefinitionKind::Comprehension(ComprehensionDefinitionKind {
-                    node: AstNodeRef::new(parsed, node),
-                    first,
-                })
-            }
+            DefinitionNodeRef::For(ForStmtDefinitionNodeRef {
+                iterable,
+                target,
+                is_async,
+            }) => DefinitionKind::For(ForStmtDefinitionKind {
+                iterable: AstNodeRef::new(parsed.clone(), iterable),
+                target: AstNodeRef::new(parsed, target),
+                is_async,
+            }),
+            DefinitionNodeRef::Comprehension(ComprehensionDefinitionNodeRef {
+                iterable,
+                target,
+                first,
+            }) => DefinitionKind::Comprehension(ComprehensionDefinitionKind {
+                iterable: AstNodeRef::new(parsed.clone(), iterable),
+                target: AstNodeRef::new(parsed, target),
+                first,
+            }),
            DefinitionNodeRef::Parameter(parameter) => match parameter {
                ast::AnyParameterRef::Variadic(parameter) => {
                    DefinitionKind::Parameter(AstNodeRef::new(parsed, parameter))
@@ -194,6 +239,15 @@ impl DefinitionNodeRef<'_> {
                    target: AstNodeRef::new(parsed, target),
                })
            }
+            DefinitionNodeRef::MatchPattern(MatchPatternDefinitionNodeRef {
+                pattern,
+                identifier,
+                index,
+            }) => DefinitionKind::MatchPattern(MatchPatternDefinitionKind {
+                pattern: AstNodeRef::new(parsed.clone(), pattern),
+                identifier: AstNodeRef::new(parsed, identifier),
+                index,
+            }),
        }
    }

@@ -212,12 +266,20 @@ impl DefinitionNodeRef<'_> {
            }) => target.into(),
            Self::AnnotatedAssignment(node) => node.into(),
            Self::AugmentedAssignment(node) => node.into(),
-            Self::Comprehension(ComprehensionDefinitionNodeRef { node, first: _ }) => node.into(),
+            Self::For(ForStmtDefinitionNodeRef {
+                iterable: _,
+                target,
+                is_async: _,
+            }) => target.into(),
+            Self::Comprehension(ComprehensionDefinitionNodeRef { target, .. }) => target.into(),
            Self::Parameter(node) => match node {
                ast::AnyParameterRef::Variadic(parameter) => parameter.into(),
                ast::AnyParameterRef::NonVariadic(parameter) => parameter.into(),
            },
            Self::WithItem(WithItemDefinitionNodeRef { node: _, target }) => target.into(),
+            Self::MatchPattern(MatchPatternDefinitionNodeRef { identifier, .. }) => {
+                identifier.into()
+            }
        }
    }
 }
@@ -232,21 +294,46 @@ pub enum DefinitionKind {
    Assignment(AssignmentDefinitionKind),
    AnnotatedAssignment(AstNodeRef<ast::StmtAnnAssign>),
    AugmentedAssignment(AstNodeRef<ast::StmtAugAssign>),
+    For(ForStmtDefinitionKind),
    Comprehension(ComprehensionDefinitionKind),
    Parameter(AstNodeRef<ast::Parameter>),
    ParameterWithDefault(AstNodeRef<ast::ParameterWithDefault>),
    WithItem(WithItemDefinitionKind),
+    MatchPattern(MatchPatternDefinitionKind),
+}
+
+#[derive(Clone, Debug)]
+#[allow(dead_code)]
+pub struct MatchPatternDefinitionKind {
+    pattern: AstNodeRef<ast::Pattern>,
+    identifier: AstNodeRef<ast::Identifier>,
+    index: u32,
+}
+
+impl MatchPatternDefinitionKind {
+    pub(crate) fn pattern(&self) -> &ast::Pattern {
+        self.pattern.node()
+    }
+
+    pub(crate) fn index(&self) -> u32 {
+        self.index
+    }
 }

 #[derive(Clone, Debug)]
 pub struct ComprehensionDefinitionKind {
-    node: AstNodeRef<ast::Comprehension>,
+    iterable: AstNodeRef<ast::Expr>,
+    target: AstNodeRef<ast::ExprName>,
    first: bool,
 }

 impl ComprehensionDefinitionKind {
-    pub(crate) fn node(&self) -> &ast::Comprehension {
-        self.node.node()
+    pub(crate) fn iterable(&self) -> &ast::Expr {
+        self.iterable.node()
+    }
+
+    pub(crate) fn target(&self) -> &ast::ExprName {
+        self.target.node()
    }

    pub(crate) fn is_first(&self) -> bool {
@@ -302,6 +389,27 @@ impl WithItemDefinitionKind {
    }
 }

+#[derive(Clone, Debug)]
+pub struct ForStmtDefinitionKind {
+    iterable: AstNodeRef<ast::Expr>,
+    target: AstNodeRef<ast::ExprName>,
+    is_async: bool,
+}
+
+impl ForStmtDefinitionKind {
+    pub(crate) fn iterable(&self) -> &ast::Expr {
+        self.iterable.node()
+    }
+
+    pub(crate) fn target(&self) -> &ast::ExprName {
+        self.target.node()
+    }
+
+    pub(crate) fn is_async(&self) -> bool {
+        self.is_async
+    }
+}
+
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
 pub(crate) struct DefinitionNodeKey(NodeKey);

@@ -347,9 +455,9 @@ impl From<&ast::StmtAugAssign> for DefinitionNodeKey {
    }
 }

-impl From<&ast::Comprehension> for DefinitionNodeKey {
-    fn from(node: &ast::Comprehension) -> Self {
-        Self(NodeKey::from_node(node))
+impl From<&ast::StmtFor> for DefinitionNodeKey {
+    fn from(value: &ast::StmtFor) -> Self {
+        Self(NodeKey::from_node(value))
    }
 }

@@ -364,3 +472,9 @@ impl From<&ast::ParameterWithDefault> for DefinitionNodeKey {
        Self(NodeKey::from_node(node))
    }
 }
+
+impl From<&ast::Identifier> for DefinitionNodeKey {
+    fn from(identifier: &ast::Identifier) -> Self {
+        Self(NodeKey::from_node(identifier))
+    }
+}
--- a/crates/red_knot_python_semantic/src/semantic_index/symbol.rs
+++ b/crates/red_knot_python_semantic/src/semantic_index/symbol.rs
@@ -149,6 +149,10 @@ impl FileScopeId {
        FileScopeId::from_u32(0)
    }

+    pub fn is_global(self) -> bool {
+        self == FileScopeId::global()
+    }
+
    pub fn to_scope_id(self, db: &dyn Db, file: File) -> ScopeId<'_> {
        let index = semantic_index(db, file);
        index.scope_ids_by_scope[self]
--- a/crates/red_knot_python_semantic/src/semantic_model.rs
+++ b/crates/red_knot_python_semantic/src/semantic_model.rs
@@ -8,7 +8,7 @@ use crate::module_name::ModuleName;
 use crate::module_resolver::{resolve_module, Module};
 use crate::semantic_index::ast_ids::HasScopedAstId;
 use crate::semantic_index::semantic_index;
-use crate::types::{definition_ty, global_symbol_ty_by_name, infer_scope_types, Type};
+use crate::types::{definition_ty, global_symbol_ty, infer_scope_types, Type};
 use crate::Db;

 pub struct SemanticModel<'db> {
@@ -40,7 +40,7 @@ impl<'db> SemanticModel<'db> {
    }

    pub fn global_symbol_ty(&self, module: &Module, symbol_name: &str) -> Type<'db> {
-        global_symbol_ty_by_name(self.db, module.file(), symbol_name)
+        global_symbol_ty(self.db, module.file(), symbol_name)
    }
 }

--- a/crates/red_knot_python_semantic/src/stdlib.rs
+++ b/crates/red_knot_python_semantic/src/stdlib.rs
@@ -0,0 +1,77 @@
+use crate::module_name::ModuleName;
+use crate::module_resolver::resolve_module;
+use crate::semantic_index::global_scope;
+use crate::semantic_index::symbol::ScopeId;
+use crate::types::{global_symbol_ty, Type};
+use crate::Db;
+
+/// Enumeration of various core stdlib modules, for which we have dedicated Salsa queries.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum CoreStdlibModule {
+    Builtins,
+    Types,
+    Typeshed,
+}
+
+impl CoreStdlibModule {
+    fn name(self) -> ModuleName {
+        let module_name = match self {
+            Self::Builtins => "builtins",
+            Self::Types => "types",
+            Self::Typeshed => "_typeshed",
+        };
+        ModuleName::new_static(module_name)
+            .unwrap_or_else(|| panic!("{module_name} should be a valid module name!"))
+    }
+}
+
+/// Lookup the type of `symbol` in a given core module
+///
+/// Returns `Unbound` if the given core module cannot be resolved for some reason
+fn core_module_symbol_ty<'db>(
+    db: &'db dyn Db,
+    core_module: CoreStdlibModule,
+    symbol: &str,
+) -> Type<'db> {
+    resolve_module(db, core_module.name())
+        .map(|module| global_symbol_ty(db, module.file(), symbol))
+        .unwrap_or(Type::Unbound)
+}
+
+/// Lookup the type of `symbol` in the builtins namespace.
+///
+/// Returns `Unbound` if the `builtins` module isn't available for some reason.
+#[inline]
+pub(crate) fn builtins_symbol_ty<'db>(db: &'db dyn Db, symbol: &str) -> Type<'db> {
+    core_module_symbol_ty(db, CoreStdlibModule::Builtins, symbol)
+}
+
+/// Lookup the type of `symbol` in the `types` module namespace.
+///
+/// Returns `Unbound` if the `types` module isn't available for some reason.
+#[inline]
+pub(crate) fn types_symbol_ty<'db>(db: &'db dyn Db, symbol: &str) -> Type<'db> {
+    core_module_symbol_ty(db, CoreStdlibModule::Types, symbol)
+}
+
+/// Lookup the type of `symbol` in the `_typeshed` module namespace.
+///
+/// Returns `Unbound` if the `_typeshed` module isn't available for some reason.
+#[inline]
+pub(crate) fn typeshed_symbol_ty<'db>(db: &'db dyn Db, symbol: &str) -> Type<'db> {
+    core_module_symbol_ty(db, CoreStdlibModule::Typeshed, symbol)
+}
+
+/// Get the scope of a core stdlib module.
+///
+/// Can return `None` if a custom typeshed is used that is missing the core module in question.
+fn core_module_scope(db: &dyn Db, core_module: CoreStdlibModule) -> Option<ScopeId<'_>> {
+    resolve_module(db, core_module.name()).map(|module| global_scope(db, module.file()))
+}
+
+/// Get the `builtins` module scope.
+///
+/// Can return `None` if a custom typeshed is used that is missing `builtins.pyi`.
+pub(crate) fn builtins_module_scope(db: &dyn Db) -> Option<ScopeId<'_>> {
+    core_module_scope(db, CoreStdlibModule::Builtins)
+}
--- a/crates/red_knot_python_semantic/src/types.rs
+++ b/crates/red_knot_python_semantic/src/types.rs
@@ -1,20 +1,23 @@
+use infer::TypeInferenceBuilder;
 use ruff_db::files::File;
-use ruff_python_ast::name::Name;
+use ruff_python_ast as ast;

-use crate::builtins::builtins_scope;
-use crate::semantic_index::definition::Definition;
+use crate::semantic_index::ast_ids::HasScopedAstId;
+use crate::semantic_index::definition::{Definition, DefinitionKind};
 use crate::semantic_index::symbol::{ScopeId, ScopedSymbolId};
 use crate::semantic_index::{
    global_scope, semantic_index, symbol_table, use_def_map, DefinitionWithConstraints,
    DefinitionWithConstraintsIterator,
 };
+use crate::stdlib::{builtins_symbol_ty, types_symbol_ty, typeshed_symbol_ty};
 use crate::types::narrow::narrowing_constraint;
 use crate::{Db, FxOrderSet};

 pub(crate) use self::builder::{IntersectionBuilder, UnionBuilder};
 pub(crate) use self::diagnostic::TypeCheckDiagnostics;
 pub(crate) use self::infer::{
-    infer_definition_types, infer_expression_types, infer_scope_types, TypeInference,
+    infer_deferred_types, infer_definition_types, infer_expression_types, infer_scope_types,
+    TypeInference,
 };

 mod builder;
@@ -38,7 +41,7 @@ pub fn check_types(db: &dyn Db, file: File) -> TypeCheckDiagnostics {
 }

 /// Infer the public type of a symbol (its type as seen from outside its scope).
-pub(crate) fn symbol_ty<'db>(
+pub(crate) fn symbol_ty_by_id<'db>(
    db: &'db dyn Db,
    scope: ScopeId<'db>,
    symbol: ScopedSymbolId,
@@ -56,30 +59,17 @@ pub(crate) fn symbol_ty<'db>(
 }

 /// Shorthand for `symbol_ty` that takes a symbol name instead of an ID.
-pub(crate) fn symbol_ty_by_name<'db>(
-    db: &'db dyn Db,
-    scope: ScopeId<'db>,
-    name: &str,
-) -> Type<'db> {
+pub(crate) fn symbol_ty<'db>(db: &'db dyn Db, scope: ScopeId<'db>, name: &str) -> Type<'db> {
    let table = symbol_table(db, scope);
    table
        .symbol_id_by_name(name)
-        .map(|symbol| symbol_ty(db, scope, symbol))
+        .map(|symbol| symbol_ty_by_id(db, scope, symbol))
        .unwrap_or(Type::Unbound)
 }

 /// Shorthand for `symbol_ty` that looks up a module-global symbol by name in a file.
-pub(crate) fn global_symbol_ty_by_name<'db>(db: &'db dyn Db, file: File, name: &str) -> Type<'db> {
-    symbol_ty_by_name(db, global_scope(db, file), name)
-}
-
-/// Shorthand for `symbol_ty` that looks up a symbol in the builtins.
-///
-/// Returns `Unbound` if the builtins module isn't available for some reason.
-pub(crate) fn builtins_symbol_ty_by_name<'db>(db: &'db dyn Db, name: &str) -> Type<'db> {
-    builtins_scope(db)
-        .map(|builtins| symbol_ty_by_name(db, builtins, name))
-        .unwrap_or(Type::Unbound)
+pub(crate) fn global_symbol_ty<'db>(db: &'db dyn Db, file: File, name: &str) -> Type<'db> {
+    symbol_ty(db, global_scope(db, file), name)
 }

 /// Infer the type of a [`Definition`].
@@ -88,6 +78,24 @@ pub(crate) fn definition_ty<'db>(db: &'db dyn Db, definition: Definition<'db>) -
    inference.definition_ty(definition)
 }

+/// Infer the type of a (possibly deferred) sub-expression of a [`Definition`].
+///
+/// ## Panics
+/// If the given expression is not a sub-expression of the given [`Definition`].
+pub(crate) fn definition_expression_ty<'db>(
+    db: &'db dyn Db,
+    definition: Definition<'db>,
+    expression: &ast::Expr,
+) -> Type<'db> {
+    let expr_id = expression.scoped_ast_id(db, definition.scope(db));
+    let inference = infer_definition_types(db, definition);
+    if let Some(ty) = inference.try_expression_ty(expr_id) {
+        ty
+    } else {
+        infer_deferred_types(db, definition).expression_ty(expr_id)
+    }
+}
+
 /// Infer the combined type of an array of [`Definition`]s, plus one optional "unbound type".
 ///
 /// Will return a union if there is more than one definition, or at least one plus an unbound
@@ -132,9 +140,9 @@ pub(crate) fn definitions_ty<'db>(
    );
    let mut all_types = unbound_ty.into_iter().chain(def_types);

-    let Some(first) = all_types.next() else {
-        panic!("definitions_ty should never be called with zero definitions and no unbound_ty.")
-    };
+    let first = all_types
+        .next()
+        .expect("definitions_ty should never be called with zero definitions and no unbound_ty.");

    if let Some(second) = all_types.next() {
        let mut builder = UnionBuilder::new(db);
@@ -151,7 +159,7 @@ pub(crate) fn definitions_ty<'db>(
 }

 /// Unique ID for a type.
-#[derive(Copy, Clone, Debug, PartialOrd, Ord, PartialEq, Eq, Hash)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 pub enum Type<'db> {
    /// the dynamic type: a statically-unknown set of values
    Any,
@@ -181,6 +189,13 @@ pub enum Type<'db> {
    IntLiteral(i64),
    /// A boolean literal, either `True` or `False`.
    BooleanLiteral(bool),
+    /// A string literal
+    StringLiteral(StringLiteralType<'db>),
+    /// A string known to originate only from literal values, but whose value is not known (unlike
+    /// `StringLiteral` above).
+    LiteralString,
+    /// A bytes literal
+    BytesLiteral(BytesLiteralType<'db>),
    // TODO protocols, callable types, overloads, generics, type vars
 }

@@ -189,14 +204,82 @@ impl<'db> Type<'db> {
        matches!(self, Type::Unbound)
    }

-    pub const fn is_unknown(&self) -> bool {
-        matches!(self, Type::Unknown)
-    }
-
    pub const fn is_never(&self) -> bool {
        matches!(self, Type::Never)
    }

+    pub const fn into_class_type(self) -> Option<ClassType<'db>> {
+        match self {
+            Type::Class(class_type) => Some(class_type),
+            _ => None,
+        }
+    }
+
+    pub fn expect_class(self) -> ClassType<'db> {
+        self.into_class_type()
+            .expect("Expected a Type::Class variant")
+    }
+
+    pub const fn into_module_type(self) -> Option<File> {
+        match self {
+            Type::Module(file) => Some(file),
+            _ => None,
+        }
+    }
+
+    pub fn expect_module(self) -> File {
+        self.into_module_type()
+            .expect("Expected a Type::Module variant")
+    }
+
+    pub const fn into_union_type(self) -> Option<UnionType<'db>> {
+        match self {
+            Type::Union(union_type) => Some(union_type),
+            _ => None,
+        }
+    }
+
+    pub fn expect_union(self) -> UnionType<'db> {
+        self.into_union_type()
+            .expect("Expected a Type::Union variant")
+    }
+
+    pub const fn into_intersection_type(self) -> Option<IntersectionType<'db>> {
+        match self {
+            Type::Intersection(intersection_type) => Some(intersection_type),
+            _ => None,
+        }
+    }
+
+    pub fn expect_intersection(self) -> IntersectionType<'db> {
+        self.into_intersection_type()
+            .expect("Expected a Type::Intersection variant")
+    }
+
+    pub const fn into_function_type(self) -> Option<FunctionType<'db>> {
+        match self {
+            Type::Function(function_type) => Some(function_type),
+            _ => None,
+        }
+    }
+
+    pub fn expect_function(self) -> FunctionType<'db> {
+        self.into_function_type()
+            .expect("Expected a Type::Function variant")
+    }
+
+    pub const fn into_int_literal_type(self) -> Option<i64> {
+        match self {
+            Type::IntLiteral(value) => Some(value),
+            _ => None,
+        }
+    }
+
+    pub fn expect_int_literal(self) -> i64 {
+        self.into_int_literal_type()
+            .expect("Expected a Type::IntLiteral variant")
+    }
+
    pub fn may_be_unbound(&self, db: &'db dyn Db) -> bool {
        match self {
            Type::Unbound => true,
@@ -211,13 +294,9 @@ impl<'db> Type<'db> {
    pub fn replace_unbound_with(&self, db: &'db dyn Db, replacement: Type<'db>) -> Type<'db> {
        match self {
            Type::Unbound => replacement,
-            Type::Union(union) => union
-                .elements(db)
-                .into_iter()
-                .fold(UnionBuilder::new(db), |builder, ty| {
-                    builder.add(ty.replace_unbound_with(db, replacement))
-                })
-                .build(),
+            Type::Union(union) => {
+                union.map(db, |element| element.replace_unbound_with(db, replacement))
+            }
            ty => *ty,
        }
    }
@@ -236,7 +315,7 @@ impl<'db> Type<'db> {
    /// us to explicitly consider whether to handle an error or propagate
    /// it up the call stack.
    #[must_use]
-    pub fn member(&self, db: &'db dyn Db, name: &Name) -> Type<'db> {
+    pub fn member(&self, db: &'db dyn Db, name: &str) -> Type<'db> {
        match self {
            Type::Any => Type::Any,
            Type::Never => {
@@ -253,19 +332,13 @@ impl<'db> Type<'db> {
                // TODO: attribute lookup on function type
                Type::Unknown
            }
-            Type::Module(file) => global_symbol_ty_by_name(db, *file, name),
+            Type::Module(file) => global_symbol_ty(db, *file, name),
            Type::Class(class) => class.class_member(db, name),
            Type::Instance(_) => {
                // TODO MRO? get_own_instance_member, get_instance_member
                Type::Unknown
            }
-            Type::Union(union) => union
-                .elements(db)
-                .iter()
-                .fold(UnionBuilder::new(db), |builder, element_ty| {
-                    builder.add(element_ty.member(db, name))
-                })
-                .build(),
+            Type::Union(union) => union.map(db, |element| element.member(db, name)),
            Type::Intersection(_) => {
                // TODO perform the get_member on each type in the intersection
                // TODO return the intersection of those results
@@ -276,11 +349,98 @@ impl<'db> Type<'db> {
                Type::Unknown
            }
            Type::BooleanLiteral(_) => Type::Unknown,
+            Type::StringLiteral(_) => {
+                // TODO defer to `typing.LiteralString`/`builtins.str` methods
+                // from typeshed's stubs
+                Type::Unknown
+            }
+            Type::LiteralString => {
+                // TODO defer to `typing.LiteralString`/`builtins.str` methods
+                // from typeshed's stubs
+                Type::Unknown
+            }
+            Type::BytesLiteral(_) => {
+                // TODO defer to Type::Instance(<bytes from typeshed>).member
+                Type::Unknown
+            }
        }
    }

+    /// Return the type resulting from calling an object of this type.
+    ///
+    /// Returns `None` if `self` is not a callable type.
    #[must_use]
-    pub fn instance(&self) -> Type<'db> {
+    pub fn call(&self, db: &'db dyn Db) -> Option<Type<'db>> {
+        match self {
+            Type::Function(function_type) => Some(function_type.return_type(db)),
+
+            // TODO annotated return type on `__new__` or metaclass `__call__`
+            Type::Class(class) => Some(Type::Instance(*class)),
+
+            // TODO: handle classes which implement the Callable protocol
+            Type::Instance(_instance_ty) => Some(Type::Unknown),
+
+            // `Any` is callable, and its return type is also `Any`.
+            Type::Any => Some(Type::Any),
+
+            Type::Unknown => Some(Type::Unknown),
+
+            // TODO: union and intersection types, if they reduce to `Callable`
+            Type::Union(_) => Some(Type::Unknown),
+            Type::Intersection(_) => Some(Type::Unknown),
+
+            _ => None,
+        }
+    }
+
+    /// Given the type of an object that is iterated over in some way,
+    /// return the type of objects that are yielded by that iteration.
+    ///
+    /// E.g., for the following loop, given the type of `x`, infer the type of `y`:
+    /// ```python
+    /// for y in x:
+    ///     pass
+    /// ```
+    fn iterate(&self, db: &'db dyn Db) -> IterationOutcome<'db> {
+        // `self` represents the type of the iterable;
+        // `__iter__` and `__next__` are both looked up on the class of the iterable:
+        let iterable_meta_type = self.to_meta_type(db);
+
+        let dunder_iter_method = iterable_meta_type.member(db, "__iter__");
+        if !dunder_iter_method.is_unbound() {
+            let Some(iterator_ty) = dunder_iter_method.call(db) else {
+                return IterationOutcome::NotIterable {
+                    not_iterable_ty: *self,
+                };
+            };
+
+            let dunder_next_method = iterator_ty.to_meta_type(db).member(db, "__next__");
+            return dunder_next_method
+                .call(db)
+                .map(|element_ty| IterationOutcome::Iterable { element_ty })
+                .unwrap_or(IterationOutcome::NotIterable {
+                    not_iterable_ty: *self,
+                });
+        }
+
+        // Although it's not considered great practice,
+        // classes that define `__getitem__` are also iterable,
+        // even if they do not define `__iter__`.
+        //
+        // TODO(Alex) this is only valid if the `__getitem__` method is annotated as
+        // accepting `int` or `SupportsIndex`
+        let dunder_get_item_method = iterable_meta_type.member(db, "__getitem__");
+
+        dunder_get_item_method
+            .call(db)
+            .map(|element_ty| IterationOutcome::Iterable { element_ty })
+            .unwrap_or(IterationOutcome::NotIterable {
+                not_iterable_ty: *self,
+            })
+    }
+
+    #[must_use]
+    pub fn to_instance(&self) -> Type<'db> {
        match self {
            Type::Any => Type::Any,
            Type::Unknown => Type::Unknown,
@@ -288,12 +448,65 @@ impl<'db> Type<'db> {
            _ => Type::Unknown, // TODO type errors
        }
    }
+
+    /// Given a type that is assumed to represent an instance of a class,
+    /// return a type that represents that class itself.
+    #[must_use]
+    pub fn to_meta_type(&self, db: &'db dyn Db) -> Type<'db> {
+        match self {
+            Type::Unbound => Type::Unbound,
+            Type::Never => Type::Never,
+            Type::Instance(class) => Type::Class(*class),
+            Type::Union(union) => union.map(db, |ty| ty.to_meta_type(db)),
+            Type::BooleanLiteral(_) => builtins_symbol_ty(db, "bool"),
+            Type::BytesLiteral(_) => builtins_symbol_ty(db, "bytes"),
+            Type::IntLiteral(_) => builtins_symbol_ty(db, "int"),
+            Type::Function(_) => types_symbol_ty(db, "FunctionType"),
+            Type::Module(_) => types_symbol_ty(db, "ModuleType"),
+            Type::None => typeshed_symbol_ty(db, "NoneType"),
+            // TODO not accurate if there's a custom metaclass...
+            Type::Class(_) => builtins_symbol_ty(db, "type"),
+            // TODO can we do better here? `type[LiteralString]`?
+            Type::StringLiteral(_) | Type::LiteralString => builtins_symbol_ty(db, "str"),
+            // TODO: `type[Any]`?
+            Type::Any => Type::Any,
+            // TODO: `type[Unknown]`?
+            Type::Unknown => Type::Unknown,
+            // TODO intersections
+            Type::Intersection(_) => Type::Unknown,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum IterationOutcome<'db> {
+    Iterable { element_ty: Type<'db> },
+    NotIterable { not_iterable_ty: Type<'db> },
+}
+
+impl<'db> IterationOutcome<'db> {
+    fn unwrap_with_diagnostic(
+        self,
+        iterable_node: ast::AnyNodeRef,
+        inference_builder: &mut TypeInferenceBuilder<'db>,
+    ) -> Type<'db> {
+        match self {
+            Self::Iterable { element_ty } => element_ty,
+            Self::NotIterable { not_iterable_ty } => {
+                inference_builder.not_iterable_diagnostic(iterable_node, not_iterable_ty);
+                Type::Unknown
+            }
+        }
+    }
 }

 #[salsa::interned]
 pub struct FunctionType<'db> {
    /// name of the function at definition
-    pub name: Name,
+    #[return_ref]
+    pub name: ast::name::Name,
+
+    definition: Definition<'db>,

    /// types of all decorators on this function
    decorators: Vec<Type<'db>>,
@@ -303,24 +516,69 @@ impl<'db> FunctionType<'db> {
    pub fn has_decorator(self, db: &dyn Db, decorator: Type<'_>) -> bool {
        self.decorators(db).contains(&decorator)
    }
+
+    /// inferred return type for this function
+    pub fn return_type(&self, db: &'db dyn Db) -> Type<'db> {
+        let definition = self.definition(db);
+        let DefinitionKind::Function(function_stmt_node) = definition.node(db) else {
+            panic!("Function type definition must have `DefinitionKind::Function`")
+        };
+
+        // TODO if a function `bar` is decorated by `foo`,
+        // where `foo` is annotated as returning a type `X` that is a subtype of `Callable`,
+        // we need to infer the return type from `X`'s return annotation
+        // rather than from `bar`'s return annotation
+        // in order to determine the type that `bar` returns
+        if !function_stmt_node.decorator_list.is_empty() {
+            return Type::Unknown;
+        }
+
+        function_stmt_node
+            .returns
+            .as_ref()
+            .map(|returns| {
+                if function_stmt_node.is_async {
+                    // TODO: generic `types.CoroutineType`!
+                    Type::Unknown
+                } else {
+                    definition_expression_ty(db, definition, returns.as_ref())
+                }
+            })
+            .unwrap_or(Type::Unknown)
+    }
 }

 #[salsa::interned]
 pub struct ClassType<'db> {
    /// Name of the class at definition
-    pub name: Name,
+    #[return_ref]
+    pub name: ast::name::Name,

-    /// Types of all class bases
-    bases: Vec<Type<'db>>,
+    definition: Definition<'db>,

    body_scope: ScopeId<'db>,
 }

 impl<'db> ClassType<'db> {
+    /// Return an iterator over the types of this class's bases.
+    ///
+    /// # Panics:
+    /// If `definition` is not a `DefinitionKind::Class`.
+    pub fn bases(&self, db: &'db dyn Db) -> impl Iterator<Item = Type<'db>> {
+        let definition = self.definition(db);
+        let DefinitionKind::Class(class_stmt_node) = definition.node(db) else {
+            panic!("Class type definition must have DefinitionKind::Class");
+        };
+        class_stmt_node
+            .bases()
+            .iter()
+            .map(move |base_expr| definition_expression_ty(db, definition, base_expr))
+    }
+
    /// Returns the class member of this class named `name`.
    ///
    /// The member resolves to a member of the class itself or any of its bases.
-    pub fn class_member(self, db: &'db dyn Db, name: &Name) -> Type<'db> {
+    pub fn class_member(self, db: &'db dyn Db, name: &str) -> Type<'db> {
        let member = self.own_class_member(db, name);
        if !member.is_unbound() {
            return member;
@@ -330,12 +588,12 @@ impl<'db> ClassType<'db> {
    }

    /// Returns the inferred type of the class member named `name`.
-    pub fn own_class_member(self, db: &'db dyn Db, name: &Name) -> Type<'db> {
+    pub fn own_class_member(self, db: &'db dyn Db, name: &str) -> Type<'db> {
        let scope = self.body_scope(db);
-        symbol_ty_by_name(db, scope, name)
+        symbol_ty(db, scope, name)
    }

-    pub fn inherited_class_member(self, db: &'db dyn Db, name: &Name) -> Type<'db> {
+    pub fn inherited_class_member(self, db: &'db dyn Db, name: &str) -> Type<'db> {
        for base in self.bases(db) {
            let member = base.member(db, name);
            if !member.is_unbound() {
@@ -350,6 +608,7 @@ impl<'db> ClassType<'db> {
 #[salsa::interned]
 pub struct UnionType<'db> {
    /// The union type includes values in any of these types.
+    #[return_ref]
    elements: FxOrderSet<Type<'db>>,
 }

@@ -357,11 +616,27 @@ impl<'db> UnionType<'db> {
    pub fn contains(&self, db: &'db dyn Db, ty: Type<'db>) -> bool {
        self.elements(db).contains(&ty)
    }
+
+    /// Apply a transformation function to all elements of the union,
+    /// and create a new union from the resulting set of types
+    pub fn map(
+        &self,
+        db: &'db dyn Db,
+        mut transform_fn: impl FnMut(&Type<'db>) -> Type<'db>,
+    ) -> Type<'db> {
+        self.elements(db)
+            .into_iter()
+            .fold(UnionBuilder::new(db), |builder, element| {
+                builder.add(transform_fn(element))
+            })
+            .build()
+    }
 }

 #[salsa::interned]
 pub struct IntersectionType<'db> {
    /// The intersection type includes only values in all of these types.
+    #[return_ref]
    positive: FxOrderSet<Type<'db>>,

    /// The intersection type does not include any value in any of these types.
@@ -369,9 +644,22 @@ pub struct IntersectionType<'db> {
    /// Negation types aren't expressible in annotations, and are most likely to arise from type
    /// narrowing along with intersections (e.g. `if not isinstance(...)`), so we represent them
    /// directly in intersections rather than as a separate type.
+    #[return_ref]
    negative: FxOrderSet<Type<'db>>,
 }

+#[salsa::interned]
+pub struct StringLiteralType<'db> {
+    #[return_ref]
+    value: Box<str>,
+}
+
+#[salsa::interned]
+pub struct BytesLiteralType<'db> {
+    #[return_ref]
+    value: Box<[u8]>,
+}
+
 #[cfg(test)]
 mod tests {
    use anyhow::Context;
@@ -420,7 +708,7 @@ mod tests {
        let foo = system_path_to_file(&db, "src/foo.py").context("Failed to resolve foo.py")?;

        let diagnostics = super::check_types(&db, foo);
-        assert_diagnostic_messages(&diagnostics, &["Import 'bar' could not be resolved."]);
+        assert_diagnostic_messages(&diagnostics, &["Cannot resolve import 'bar'."]);

        Ok(())
    }
@@ -433,7 +721,7 @@ mod tests {
            .unwrap();
        let foo = system_path_to_file(&db, "src/foo.py").unwrap();
        let diagnostics = super::check_types(&db, foo);
-        assert_diagnostic_messages(&diagnostics, &["Import 'bar' could not be resolved."]);
+        assert_diagnostic_messages(&diagnostics, &["Cannot resolve import 'bar'."]);
    }

    #[test]
@@ -445,15 +733,9 @@ mod tests {

        let b_file = system_path_to_file(&db, "/src/b.py").unwrap();
        let b_file_diagnostics = super::check_types(&db, b_file);
-        assert_diagnostic_messages(
-            &b_file_diagnostics,
-            &["Could not resolve import of 'thing' from 'a'"],
-        );
+        assert_diagnostic_messages(&b_file_diagnostics, &["Module 'a' has no member 'thing'"]);
    }

-    #[ignore = "\
-A spurious second 'Unresolved import' diagnostic message is emitted on `b.py`, \
-despite the symbol existing in the symbol table for `a.py`"]
    #[test]
    fn resolved_import_of_symbol_from_unresolved_import() {
        let mut db = setup_db();
@@ -466,10 +748,7 @@ despite the symbol existing in the symbol table for `a.py`"]

        let a_file = system_path_to_file(&db, "/src/a.py").unwrap();
        let a_file_diagnostics = super::check_types(&db, a_file);
-        assert_diagnostic_messages(
-            &a_file_diagnostics,
-            &["Import 'foo' could not be resolved."],
-        );
+        assert_diagnostic_messages(&a_file_diagnostics, &["Cannot resolve import 'foo'."]);

        // Importing the unresolved import into a second first-party file should not trigger
        // an additional "unresolved import" violation
@@ -477,4 +756,135 @@ despite the symbol existing in the symbol table for `a.py`"]
        let b_file_diagnostics = super::check_types(&db, b_file);
        assert_eq!(&*b_file_diagnostics, &[]);
    }
+
+    #[test]
+    fn invalid_callable() {
+        let mut db = setup_db();
+
+        db.write_dedented(
+            "src/a.py",
+            "
+            nonsense = 123
+            x = nonsense()
+            ",
+        )
+        .unwrap();
+
+        let a_file = system_path_to_file(&db, "/src/a.py").unwrap();
+        let a_file_diagnostics = super::check_types(&db, a_file);
+        assert_diagnostic_messages(
+            &a_file_diagnostics,
+            &["Object of type 'Literal[123]' is not callable"],
+        );
+    }
+
+    #[test]
+    fn invalid_iterable() {
+        let mut db = setup_db();
+
+        db.write_dedented(
+            "src/a.py",
+            "
+            nonsense = 123
+            for x in nonsense:
+                pass
+            ",
+        )
+        .unwrap();
+
+        let a_file = system_path_to_file(&db, "/src/a.py").unwrap();
+        let a_file_diagnostics = super::check_types(&db, a_file);
+        assert_diagnostic_messages(
+            &a_file_diagnostics,
+            &["Object of type 'Literal[123]' is not iterable"],
+        );
+    }
+
+    #[test]
+    fn new_iteration_protocol_takes_precedence_over_old_style() {
+        let mut db = setup_db();
+
+        db.write_dedented(
+            "src/a.py",
+            "
+            class NotIterable:
+                def __getitem__(self, key: int) -> int:
+                    return 42
+
+                __iter__ = None
+
+            for x in NotIterable():
+                pass
+            ",
+        )
+        .unwrap();
+
+        let a_file = system_path_to_file(&db, "/src/a.py").unwrap();
+        let a_file_diagnostics = super::check_types(&db, a_file);
+        assert_diagnostic_messages(
+            &a_file_diagnostics,
+            &["Object of type 'NotIterable' is not iterable"],
+        );
+    }
+
+    #[test]
+    fn starred_expressions_must_be_iterable() {
+        let mut db = setup_db();
+
+        db.write_dedented(
+            "src/a.py",
+            "
+            class NotIterable: pass
+
+            class Iterator:
+                def __next__(self) -> int:
+                    return 42
+
+            class Iterable:
+                def __iter__(self) -> Iterator:
+
+            x = [*NotIterable()]
+            y = [*Iterable()]
+            ",
+        )
+        .unwrap();
+
+        let a_file = system_path_to_file(&db, "/src/a.py").unwrap();
+        let a_file_diagnostics = super::check_types(&db, a_file);
+        assert_diagnostic_messages(
+            &a_file_diagnostics,
+            &["Object of type 'NotIterable' is not iterable"],
+        );
+    }
+
+    #[test]
+    fn yield_from_expression_must_be_iterable() {
+        let mut db = setup_db();
+
+        db.write_dedented(
+            "src/a.py",
+            "
+            class NotIterable: pass
+
+            class Iterator:
+                def __next__(self) -> int:
+                    return 42
+
+            class Iterable:
+                def __iter__(self) -> Iterator:
+
+            def generator_function():
+                yield from Iterable()
+                yield from NotIterable()
+            ",
+        )
+        .unwrap();
+
+        let a_file = system_path_to_file(&db, "/src/a.py").unwrap();
+        let a_file_diagnostics = super::check_types(&db, a_file);
+        assert_diagnostic_messages(
+            &a_file_diagnostics,
+            &["Object of type 'NotIterable' is not iterable"],
+        );
+    }
 }
--- a/crates/red_knot_python_semantic/src/types/builder.rs
+++ b/crates/red_knot_python_semantic/src/types/builder.rs
@@ -25,8 +25,9 @@
 //!   * No type in an intersection can be a supertype of any other type in the intersection (just
 //!     eliminate the supertype from the intersection).
 //!   * An intersection containing two non-overlapping types should simplify to [`Type::Never`].
-use crate::types::{IntersectionType, Type, UnionType};
+use crate::types::{builtins_symbol_ty, IntersectionType, Type, UnionType};
 use crate::{Db, FxOrderSet};
+use ordermap::set::MutableValues;

 pub(crate) struct UnionBuilder<'db> {
    elements: FxOrderSet<Type<'db>>,
@@ -45,7 +46,7 @@ impl<'db> UnionBuilder<'db> {
    pub(crate) fn add(mut self, ty: Type<'db>) -> Self {
        match ty {
            Type::Union(union) => {
-                self.elements.extend(&union.elements(self.db));
+                self.elements.extend(union.elements(self.db));
            }
            Type::Never => {}
            _ => {
@@ -56,11 +57,36 @@ impl<'db> UnionBuilder<'db> {
        self
    }

-    pub(crate) fn build(self) -> Type<'db> {
+    /// Performs the following normalizations:
+    ///     - Replaces `Literal[True,False]` with `bool`.
+    ///     - TODO For enums `E` with members `X1`,...,`Xn`, replaces
+    ///     `Literal[E.X1,...,E.Xn]` with `E`.
+    fn simplify(&mut self) {
+        if let Some(true_index) = self.elements.get_index_of(&Type::BooleanLiteral(true)) {
+            if self.elements.contains(&Type::BooleanLiteral(false)) {
+                *self.elements.get_index_mut2(true_index).unwrap() =
+                    builtins_symbol_ty(self.db, "bool");
+                self.elements.remove(&Type::BooleanLiteral(false));
+            }
+        }
+    }
+
+    pub(crate) fn build(mut self) -> Type<'db> {
        match self.elements.len() {
            0 => Type::Never,
            1 => self.elements[0],
-            _ => Type::Union(UnionType::new(self.db, self.elements)),
+            _ => {
+                self.simplify();
+
+                match self.elements.len() {
+                    0 => Type::Never,
+                    1 => self.elements[0],
+                    _ => {
+                        self.elements.shrink_to_fit();
+                        Type::Union(UnionType::new(self.db, self.elements))
+                    }
+                }
+            }
        }
    }
 }
@@ -247,25 +273,48 @@ impl<'db> InnerIntersectionBuilder<'db> {
 mod tests {
    use super::{IntersectionBuilder, IntersectionType, Type, UnionBuilder, UnionType};
    use crate::db::tests::TestDb;
-
-    fn setup_db() -> TestDb {
-        TestDb::new()
-    }
+    use crate::program::{Program, SearchPathSettings};
+    use crate::python_version::PythonVersion;
+    use crate::types::builtins_symbol_ty;
+    use crate::ProgramSettings;
+    use ruff_db::system::{DbWithTestSystem, SystemPathBuf};

    impl<'db> UnionType<'db> {
        fn elements_vec(self, db: &'db TestDb) -> Vec<Type<'db>> {
-            self.elements(db).into_iter().collect()
+            self.elements(db).into_iter().copied().collect()
        }
    }

+    fn setup_db() -> TestDb {
+        let db = TestDb::new();
+
+        let src_root = SystemPathBuf::from("/src");
+        db.memory_file_system()
+            .create_directory_all(&src_root)
+            .unwrap();
+
+        Program::from_settings(
+            &db,
+            &ProgramSettings {
+                target_version: PythonVersion::default(),
+                search_paths: SearchPathSettings::new(src_root),
+            },
+        )
+        .expect("Valid search path settings");
+
+        db
+    }
+
    #[test]
    fn build_union() {
        let db = setup_db();
        let t0 = Type::IntLiteral(0);
        let t1 = Type::IntLiteral(1);
-        let Type::Union(union) = UnionBuilder::new(&db).add(t0).add(t1).build() else {
-            panic!("expected a union");
-        };
+        let union = UnionBuilder::new(&db)
+            .add(t0)
+            .add(t1)
+            .build()
+            .expect_union();

        assert_eq!(union.elements_vec(&db), &[t0, t1]);
    }
@@ -296,6 +345,34 @@ mod tests {
        assert_eq!(ty, t0);
    }

+    #[test]
+    fn build_union_bool() {
+        let db = setup_db();
+        let bool_ty = builtins_symbol_ty(&db, "bool");
+
+        let t0 = Type::BooleanLiteral(true);
+        let t1 = Type::BooleanLiteral(true);
+        let t2 = Type::BooleanLiteral(false);
+        let t3 = Type::IntLiteral(17);
+
+        let union = UnionBuilder::new(&db)
+            .add(t0)
+            .add(t1)
+            .add(t3)
+            .build()
+            .expect_union();
+        assert_eq!(union.elements_vec(&db), &[t0, t3]);
+        let union = UnionBuilder::new(&db)
+            .add(t0)
+            .add(t1)
+            .add(t2)
+            .add(t3)
+            .build()
+            .expect_union();
+
+        assert_eq!(union.elements_vec(&db), &[bool_ty, t3]);
+    }
+
    #[test]
    fn build_union_flatten() {
        let db = setup_db();
@@ -303,20 +380,22 @@ mod tests {
        let t1 = Type::IntLiteral(1);
        let t2 = Type::IntLiteral(2);
        let u1 = UnionBuilder::new(&db).add(t0).add(t1).build();
-        let Type::Union(union) = UnionBuilder::new(&db).add(u1).add(t2).build() else {
-            panic!("expected a union");
-        };
+        let union = UnionBuilder::new(&db)
+            .add(u1)
+            .add(t2)
+            .build()
+            .expect_union();

        assert_eq!(union.elements_vec(&db), &[t0, t1, t2]);
    }

    impl<'db> IntersectionType<'db> {
        fn pos_vec(self, db: &'db TestDb) -> Vec<Type<'db>> {
-            self.positive(db).into_iter().collect()
+            self.positive(db).into_iter().copied().collect()
        }

        fn neg_vec(self, db: &'db TestDb) -> Vec<Type<'db>> {
-            self.negative(db).into_iter().collect()
+            self.negative(db).into_iter().copied().collect()
        }
    }

@@ -325,16 +404,14 @@ mod tests {
        let db = setup_db();
        let t0 = Type::IntLiteral(0);
        let ta = Type::Any;
-        let Type::Intersection(inter) = IntersectionBuilder::new(&db)
+        let intersection = IntersectionBuilder::new(&db)
            .add_positive(ta)
            .add_negative(t0)
            .build()
-        else {
-            panic!("expected to be an intersection");
-        };
+            .expect_intersection();

-        assert_eq!(inter.pos_vec(&db), &[ta]);
-        assert_eq!(inter.neg_vec(&db), &[t0]);
+        assert_eq!(intersection.pos_vec(&db), &[ta]);
+        assert_eq!(intersection.neg_vec(&db), &[t0]);
    }

    #[test]
@@ -347,16 +424,14 @@ mod tests {
            .add_positive(ta)
            .add_negative(t1)
            .build();
-        let Type::Intersection(inter) = IntersectionBuilder::new(&db)
+        let intersection = IntersectionBuilder::new(&db)
            .add_positive(t2)
            .add_positive(i0)
            .build()
-        else {
-            panic!("expected to be an intersection");
-        };
+            .expect_intersection();

-        assert_eq!(inter.pos_vec(&db), &[t2, ta]);
-        assert_eq!(inter.neg_vec(&db), &[t1]);
+        assert_eq!(intersection.pos_vec(&db), &[t2, ta]);
+        assert_eq!(intersection.neg_vec(&db), &[t1]);
    }

    #[test]
@@ -369,16 +444,14 @@ mod tests {
            .add_positive(ta)
            .add_negative(t1)
            .build();
-        let Type::Intersection(inter) = IntersectionBuilder::new(&db)
+        let intersection = IntersectionBuilder::new(&db)
            .add_positive(t2)
            .add_negative(i0)
            .build()
-        else {
-            panic!("expected to be an intersection");
-        };
+            .expect_intersection();

-        assert_eq!(inter.pos_vec(&db), &[t2, t1]);
-        assert_eq!(inter.neg_vec(&db), &[ta]);
+        assert_eq!(intersection.pos_vec(&db), &[t2, t1]);
+        assert_eq!(intersection.neg_vec(&db), &[ta]);
    }

    #[test]
@@ -389,13 +462,11 @@ mod tests {
        let ta = Type::Any;
        let u0 = UnionBuilder::new(&db).add(t0).add(t1).build();

-        let Type::Union(union) = IntersectionBuilder::new(&db)
+        let union = IntersectionBuilder::new(&db)
            .add_positive(ta)
            .add_positive(u0)
            .build()
-        else {
-            panic!("expected a union");
-        };
+            .expect_union();
        let [Type::Intersection(i0), Type::Intersection(i1)] = union.elements_vec(&db)[..] else {
            panic!("expected a union of two intersections");
        };
--- a/crates/red_knot_python_semantic/src/types/display.rs
+++ b/crates/red_knot_python_semantic/src/types/display.rs
@@ -2,13 +2,20 @@

 use std::fmt::{Display, Formatter};

+use ruff_python_ast::str::Quote;
+use ruff_python_literal::escape::AsciiEscape;
+
 use crate::types::{IntersectionType, Type, UnionType};
-use crate::Db;
+use crate::{Db, FxOrderMap};

 impl<'db> Type<'db> {
    pub fn display(&'db self, db: &'db dyn Db) -> DisplayType<'db> {
        DisplayType { ty: self, db }
    }
+
+    fn representation(&'db self, db: &'db dyn Db) -> DisplayRepresentation<'db> {
+        DisplayRepresentation { db, ty: self }
+    }
 }

 #[derive(Copy, Clone)]
@@ -18,6 +25,39 @@ pub struct DisplayType<'db> {
 }

 impl Display for DisplayType<'_> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        let representation = self.ty.representation(self.db);
+        if matches!(
+            self.ty,
+            Type::IntLiteral(_)
+                | Type::BooleanLiteral(_)
+                | Type::StringLiteral(_)
+                | Type::BytesLiteral(_)
+                | Type::Class(_)
+                | Type::Function(_)
+        ) {
+            write!(f, "Literal[{representation}]",)
+        } else {
+            representation.fmt(f)
+        }
+    }
+}
+
+impl std::fmt::Debug for DisplayType<'_> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        std::fmt::Display::fmt(self, f)
+    }
+}
+
+/// Writes the string representation of a type, which is the value displayed either as
+/// `Literal[<repr>]` or `Literal[<repr1>, <repr2>]` for literal types or as `<repr>` for
+/// non literals
+struct DisplayRepresentation<'db> {
+    ty: &'db Type<'db>,
+    db: &'db dyn Db,
+}
+
+impl std::fmt::Display for DisplayRepresentation<'_> {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match self.ty {
            Type::Any => f.write_str("Any"),
@@ -29,25 +69,27 @@ impl Display for DisplayType<'_> {
                write!(f, "<module '{:?}'>", file.path(self.db))
            }
            // TODO functions and classes should display using a fully qualified name
-            Type::Class(class) => write!(f, "Literal[{}]", class.name(self.db)),
-            Type::Instance(class) => f.write_str(&class.name(self.db)),
-            Type::Function(function) => write!(f, "Literal[{}]", function.name(self.db)),
+            Type::Class(class) => f.write_str(class.name(self.db)),
+            Type::Instance(class) => f.write_str(class.name(self.db)),
+            Type::Function(function) => f.write_str(function.name(self.db)),
            Type::Union(union) => union.display(self.db).fmt(f),
            Type::Intersection(intersection) => intersection.display(self.db).fmt(f),
-            Type::IntLiteral(n) => write!(f, "Literal[{n}]"),
-            Type::BooleanLiteral(boolean) => {
-                write!(f, "Literal[{}]", if *boolean { "True" } else { "False" })
+            Type::IntLiteral(n) => write!(f, "{n}"),
+            Type::BooleanLiteral(boolean) => f.write_str(if *boolean { "True" } else { "False" }),
+            Type::StringLiteral(string) => {
+                write!(f, r#""{}""#, string.value(self.db).replace('"', r#"\""#))
+            }
+            Type::LiteralString => f.write_str("LiteralString"),
+            Type::BytesLiteral(bytes) => {
+                let escape =
+                    AsciiEscape::with_preferred_quote(bytes.value(self.db).as_ref(), Quote::Double);
+
+                escape.bytes_repr().write(f)
            }
        }
    }
 }

-impl std::fmt::Debug for DisplayType<'_> {
-    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
-        std::fmt::Display::fmt(self, f)
-    }
-}
-
 impl<'db> UnionType<'db> {
    fn display(&'db self, db: &'db dyn Db) -> DisplayUnionType<'db> {
        DisplayUnionType { db, ty: self }
@@ -61,45 +103,58 @@ struct DisplayUnionType<'db> {

 impl Display for DisplayUnionType<'_> {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
-        let union = self.ty;
+        let elements = self.ty.elements(self.db);

-        let (int_literals, other_types): (Vec<Type>, Vec<Type>) = union
-            .elements(self.db)
-            .iter()
-            .copied()
-            .partition(|ty| matches!(ty, Type::IntLiteral(_)));
+        // Group literal types by kind.
+        let mut grouped_literals = FxOrderMap::default();
+
+        for element in elements {
+            if let Ok(literal_kind) = LiteralTypeKind::try_from(*element) {
+                grouped_literals
+                    .entry(literal_kind)
+                    .or_insert_with(Vec::new)
+                    .push(*element);
+            }
+        }

        let mut first = true;
-        if !int_literals.is_empty() {
-            f.write_str("Literal[")?;
-            let mut nums: Vec<_> = int_literals
-                .into_iter()
-                .filter_map(|ty| {
-                    if let Type::IntLiteral(n) = ty {
-                        Some(n)
-                    } else {
-                        None
-                    }
-                })
-                .collect();
-            nums.sort_unstable();
-            for num in nums {
+
+        // Print all types, but write all literals together (while preserving their position).
+        for ty in elements {
+            if let Ok(literal_kind) = LiteralTypeKind::try_from(*ty) {
+                let Some(mut literals) = grouped_literals.remove(&literal_kind) else {
+                    continue;
+                };
+
                if !first {
-                    f.write_str(", ")?;
+                    f.write_str(" | ")?;
+                };
+
+                f.write_str("Literal[")?;
+
+                if literal_kind == LiteralTypeKind::IntLiteral {
+                    literals.sort_unstable_by_key(|ty| ty.expect_int_literal());
                }
-                write!(f, "{num}")?;
-                first = false;
+
+                for (i, literal_ty) in literals.iter().enumerate() {
+                    if i > 0 {
+                        f.write_str(", ")?;
+                    }
+                    literal_ty.representation(self.db).fmt(f)?;
+                }
+                f.write_str("]")?;
+            } else {
+                if !first {
+                    f.write_str(" | ")?;
+                };
+
+                ty.display(self.db).fmt(f)?;
            }
-            f.write_str("]")?;
+
+            first = false;
        }

-        for ty in other_types {
-            if !first {
-                f.write_str(" | ")?;
-            };
-            first = false;
-            write!(f, "{}", ty.display(self.db))?;
-        }
+        debug_assert!(grouped_literals.is_empty());

        Ok(())
    }
@@ -111,6 +166,30 @@ impl std::fmt::Debug for DisplayUnionType<'_> {
    }
 }

+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
+enum LiteralTypeKind {
+    Class,
+    Function,
+    IntLiteral,
+    StringLiteral,
+    BytesLiteral,
+}
+
+impl TryFrom<Type<'_>> for LiteralTypeKind {
+    type Error = ();
+
+    fn try_from(value: Type<'_>) -> Result<Self, Self::Error> {
+        match value {
+            Type::Class(_) => Ok(Self::Class),
+            Type::Function(_) => Ok(Self::Function),
+            Type::IntLiteral(_) => Ok(Self::IntLiteral),
+            Type::StringLiteral(_) => Ok(Self::StringLiteral),
+            Type::BytesLiteral(_) => Ok(Self::BytesLiteral),
+            _ => Err(()),
+        }
+    }
+}
+
 impl<'db> IntersectionType<'db> {
    fn display(&'db self, db: &'db dyn Db) -> DisplayIntersectionType<'db> {
        DisplayIntersectionType { db, ty: self }
@@ -150,3 +229,89 @@ impl std::fmt::Debug for DisplayIntersectionType<'_> {
        std::fmt::Display::fmt(self, f)
    }
 }
+
+#[cfg(test)]
+mod tests {
+    use ruff_db::files::system_path_to_file;
+    use ruff_db::system::{DbWithTestSystem, SystemPathBuf};
+
+    use crate::db::tests::TestDb;
+    use crate::types::{global_symbol_ty, BytesLiteralType, StringLiteralType, Type, UnionBuilder};
+    use crate::{Program, ProgramSettings, PythonVersion, SearchPathSettings};
+
+    fn setup_db() -> TestDb {
+        let db = TestDb::new();
+
+        let src_root = SystemPathBuf::from("/src");
+        db.memory_file_system()
+            .create_directory_all(&src_root)
+            .unwrap();
+
+        Program::from_settings(
+            &db,
+            &ProgramSettings {
+                target_version: PythonVersion::default(),
+                search_paths: SearchPathSettings::new(src_root),
+            },
+        )
+        .expect("Valid search path settings");
+
+        db
+    }
+
+    #[test]
+    fn test_condense_literal_display_by_type() -> anyhow::Result<()> {
+        let mut db = setup_db();
+
+        db.write_dedented(
+            "src/main.py",
+            "
+            def foo(x: int) -> int:
+                return x + 1
+
+            def bar(s: str) -> str:
+                return s
+
+            class A: ...
+            class B: ...
+            ",
+        )?;
+        let mod_file = system_path_to_file(&db, "src/main.py").expect("Expected file to exist.");
+
+        let vec: Vec<Type<'_>> = vec![
+            Type::Unknown,
+            Type::IntLiteral(-1),
+            global_symbol_ty(&db, mod_file, "A"),
+            Type::StringLiteral(StringLiteralType::new(&db, Box::from("A"))),
+            Type::BytesLiteral(BytesLiteralType::new(&db, Box::from([0]))),
+            Type::BytesLiteral(BytesLiteralType::new(&db, Box::from([7]))),
+            Type::IntLiteral(0),
+            Type::IntLiteral(1),
+            Type::StringLiteral(StringLiteralType::new(&db, Box::from("B"))),
+            global_symbol_ty(&db, mod_file, "foo"),
+            global_symbol_ty(&db, mod_file, "bar"),
+            global_symbol_ty(&db, mod_file, "B"),
+            Type::BooleanLiteral(true),
+            Type::None,
+        ];
+        let builder = vec.iter().fold(UnionBuilder::new(&db), |builder, literal| {
+            builder.add(*literal)
+        });
+        let union = builder.build().expect_union();
+        let display = format!("{}", union.display(&db));
+        assert_eq!(
+            display,
+            concat!(
+                "Unknown | ",
+                "Literal[-1, 0, 1] | ",
+                "Literal[A, B] | ",
+                "Literal[\"A\", \"B\"] | ",
+                "Literal[b\"\\x00\", b\"\\x07\"] | ",
+                "Literal[foo, bar] | ",
+                "Literal[True] | ",
+                "None"
+            )
+        );
+        Ok(())
+    }
+}
--- a/crates/red_knot_python_semantic/src/types/infer.rs
+++ b/crates/red_knot_python_semantic/src/types/infer.rs
--- a/crates/red_knot_python_semantic/vendor/typeshed/source_commit.txt
+++ b/crates/red_knot_python_semantic/vendor/typeshed/source_commit.txt
@@ -1 +1 @@
-1ace5718deaf3041f8e3d1dc9c9e8a8e830e517f
+23d867efb2df6de5600f64656f1aa8a83e06109e
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/_ast.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/_ast.pyi
@@ -1,7 +1,7 @@
 import sys
 import typing_extensions
 from typing import Any, ClassVar, Generic, Literal, TypedDict, overload
-from typing_extensions import Unpack
+from typing_extensions import Self, Unpack

 PyCF_ONLY_AST: Literal[1024]
 PyCF_TYPE_COMMENTS: Literal[4096]
@@ -34,6 +34,9 @@ class AST:
    if sys.version_info >= (3, 13):
        _field_types: ClassVar[dict[str, Any]]

+    if sys.version_info >= (3, 14):
+        def __replace__(self) -> Self: ...
+
 class mod(AST): ...
 class type_ignore(AST): ...

@@ -44,6 +47,9 @@ class TypeIgnore(type_ignore):
    tag: str
    def __init__(self, lineno: int, tag: str) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, lineno: int = ..., tag: str = ...) -> Self: ...
+
 class FunctionType(mod):
    if sys.version_info >= (3, 10):
        __match_args__ = ("argtypes", "returns")
@@ -57,6 +63,9 @@ class FunctionType(mod):
    else:
        def __init__(self, argtypes: list[expr], returns: expr) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, argtypes: list[expr] = ..., returns: expr = ...) -> Self: ...
+
 class Module(mod):
    if sys.version_info >= (3, 10):
        __match_args__ = ("body", "type_ignores")
@@ -67,6 +76,9 @@ class Module(mod):
    else:
        def __init__(self, body: list[stmt], type_ignores: list[TypeIgnore]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, body: list[stmt] = ..., type_ignores: list[TypeIgnore] = ...) -> Self: ...
+
 class Interactive(mod):
    if sys.version_info >= (3, 10):
        __match_args__ = ("body",)
@@ -76,12 +88,18 @@ class Interactive(mod):
    else:
        def __init__(self, body: list[stmt]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, body: list[stmt] = ...) -> Self: ...
+
 class Expression(mod):
    if sys.version_info >= (3, 10):
        __match_args__ = ("body",)
    body: expr
    def __init__(self, body: expr) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, body: expr = ...) -> Self: ...
+
 class stmt(AST):
    lineno: int
    col_offset: int
@@ -89,6 +107,9 @@ class stmt(AST):
    end_col_offset: int | None
    def __init__(self, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class FunctionDef(stmt):
    if sys.version_info >= (3, 12):
        __match_args__ = ("name", "args", "body", "decorator_list", "returns", "type_comment", "type_params")
@@ -152,6 +173,19 @@ class FunctionDef(stmt):
            **kwargs: Unpack[_Attributes],
        ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            name: _Identifier = ...,
+            args: arguments = ...,
+            body: list[stmt] = ...,
+            decorator_list: list[expr] = ...,
+            returns: expr | None = ...,
+            type_comment: str | None = ...,
+            type_params: list[type_param] = ...,
+        ) -> Self: ...
+
 class AsyncFunctionDef(stmt):
    if sys.version_info >= (3, 12):
        __match_args__ = ("name", "args", "body", "decorator_list", "returns", "type_comment", "type_params")
@@ -215,6 +249,19 @@ class AsyncFunctionDef(stmt):
            **kwargs: Unpack[_Attributes],
        ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            name: _Identifier = ...,
+            args: arguments = ...,
+            body: list[stmt],
+            decorator_list: list[expr],
+            returns: expr | None,
+            type_comment: str | None,
+            type_params: list[type_param],
+        ) -> Self: ...
+
 class ClassDef(stmt):
    if sys.version_info >= (3, 12):
        __match_args__ = ("name", "bases", "keywords", "body", "decorator_list", "type_params")
@@ -260,12 +307,28 @@ class ClassDef(stmt):
            **kwargs: Unpack[_Attributes],
        ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            name: _Identifier,
+            bases: list[expr],
+            keywords: list[keyword],
+            body: list[stmt],
+            decorator_list: list[expr],
+            type_params: list[type_param],
+            **kwargs: Unpack[_Attributes],
+        ) -> Self: ...
+
 class Return(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("value",)
    value: expr | None
    def __init__(self, value: expr | None = None, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, value: expr | None = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Delete(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("targets",)
@@ -275,6 +338,9 @@ class Delete(stmt):
    else:
        def __init__(self, targets: list[expr], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, targets: list[expr] = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Assign(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("targets", "value", "type_comment")
@@ -295,6 +361,11 @@ class Assign(stmt):
            self, targets: list[expr], value: expr, type_comment: str | None = None, **kwargs: Unpack[_Attributes]
        ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, targets: list[expr] = ..., value: expr = ..., type_comment: str | None = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class AugAssign(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("target", "op", "value")
@@ -305,6 +376,16 @@ class AugAssign(stmt):
        self, target: Name | Attribute | Subscript, op: operator, value: expr, **kwargs: Unpack[_Attributes]
    ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            target: Name | Attribute | Subscript = ...,
+            op: operator = ...,
+            value: expr = ...,
+            **kwargs: Unpack[_Attributes],
+        ) -> Self: ...
+
 class AnnAssign(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("target", "annotation", "value", "simple")
@@ -332,6 +413,17 @@ class AnnAssign(stmt):
        **kwargs: Unpack[_Attributes],
    ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            target: Name | Attribute | Subscript = ...,
+            annotation: expr = ...,
+            value: expr | None = ...,
+            simple: int = ...,
+            **kwargs: Unpack[_Attributes],
+        ) -> Self: ...
+
 class For(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("target", "iter", "body", "orelse", "type_comment")
@@ -361,6 +453,18 @@ class For(stmt):
            **kwargs: Unpack[_Attributes],
        ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            target: expr = ...,
+            iter: expr = ...,
+            body: list[stmt] = ...,
+            orelse: list[stmt] = ...,
+            type_comment: str | None = ...,
+            **kwargs: Unpack[_Attributes],
+        ) -> Self: ...
+
 class AsyncFor(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("target", "iter", "body", "orelse", "type_comment")
@@ -390,6 +494,18 @@ class AsyncFor(stmt):
            **kwargs: Unpack[_Attributes],
        ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            target: expr = ...,
+            iter: expr = ...,
+            body: list[stmt] = ...,
+            orelse: list[stmt] = ...,
+            type_comment: str | None = ...,
+            **kwargs: Unpack[_Attributes],
+        ) -> Self: ...
+
 class While(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("test", "body", "orelse")
@@ -403,6 +519,9 @@ class While(stmt):
    else:
        def __init__(self, test: expr, body: list[stmt], orelse: list[stmt], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, test: expr, body: list[stmt], orelse: list[stmt], **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class If(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("test", "body", "orelse")
@@ -416,6 +535,11 @@ class If(stmt):
    else:
        def __init__(self, test: expr, body: list[stmt], orelse: list[stmt], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, test: expr = ..., body: list[stmt] = ..., orelse: list[stmt] = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class With(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("items", "body", "type_comment")
@@ -435,6 +559,16 @@ class With(stmt):
            self, items: list[withitem], body: list[stmt], type_comment: str | None = None, **kwargs: Unpack[_Attributes]
        ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            items: list[withitem] = ...,
+            body: list[stmt] = ...,
+            type_comment: str | None = ...,
+            **kwargs: Unpack[_Attributes],
+        ) -> Self: ...
+
 class AsyncWith(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("items", "body", "type_comment")
@@ -454,6 +588,16 @@ class AsyncWith(stmt):
            self, items: list[withitem], body: list[stmt], type_comment: str | None = None, **kwargs: Unpack[_Attributes]
        ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            items: list[withitem] = ...,
+            body: list[stmt] = ...,
+            type_comment: str | None = ...,
+            **kwargs: Unpack[_Attributes],
+        ) -> Self: ...
+
 class Raise(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("exc", "cause")
@@ -461,6 +605,9 @@ class Raise(stmt):
    cause: expr | None
    def __init__(self, exc: expr | None = None, cause: expr | None = None, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, exc: expr | None = ..., cause: expr | None = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Try(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("body", "handlers", "orelse", "finalbody")
@@ -487,6 +634,17 @@ class Try(stmt):
            **kwargs: Unpack[_Attributes],
        ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            body: list[stmt] = ...,
+            handlers: list[ExceptHandler] = ...,
+            orelse: list[stmt] = ...,
+            finalbody: list[stmt] = ...,
+            **kwargs: Unpack[_Attributes],
+        ) -> Self: ...
+
 if sys.version_info >= (3, 11):
    class TryStar(stmt):
        __match_args__ = ("body", "handlers", "orelse", "finalbody")
@@ -513,6 +671,17 @@ if sys.version_info >= (3, 11):
                **kwargs: Unpack[_Attributes],
            ) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(
+                self,
+                *,
+                body: list[stmt] = ...,
+                handlers: list[ExceptHandler] = ...,
+                orelse: list[stmt] = ...,
+                finalbody: list[stmt] = ...,
+                **kwargs: Unpack[_Attributes],
+            ) -> Self: ...
+
 class Assert(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("test", "msg")
@@ -520,6 +689,9 @@ class Assert(stmt):
    msg: expr | None
    def __init__(self, test: expr, msg: expr | None = None, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, test: expr, msg: expr | None, **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Import(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("names",)
@@ -529,6 +701,9 @@ class Import(stmt):
    else:
        def __init__(self, names: list[alias], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, names: list[alias] = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class ImportFrom(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("module", "names", "level")
@@ -550,6 +725,11 @@ class ImportFrom(stmt):
            self, module: str | None = None, *, names: list[alias], level: int, **kwargs: Unpack[_Attributes]
        ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, module: str | None = ..., names: list[alias] = ..., level: int = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class Global(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("names",)
@@ -559,6 +739,9 @@ class Global(stmt):
    else:
        def __init__(self, names: list[_Identifier], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, names: list[_Identifier], **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Nonlocal(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("names",)
@@ -568,12 +751,18 @@ class Nonlocal(stmt):
    else:
        def __init__(self, names: list[_Identifier], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, names: list[_Identifier] = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Expr(stmt):
    if sys.version_info >= (3, 10):
        __match_args__ = ("value",)
    value: expr
    def __init__(self, value: expr, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, value: expr = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Pass(stmt): ...
 class Break(stmt): ...
 class Continue(stmt): ...
@@ -585,6 +774,9 @@ class expr(AST):
    end_col_offset: int | None
    def __init__(self, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class BoolOp(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("op", "values")
@@ -595,6 +787,9 @@ class BoolOp(expr):
    else:
        def __init__(self, op: boolop, values: list[expr], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, op: boolop = ..., values: list[expr] = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class BinOp(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("left", "op", "right")
@@ -603,6 +798,11 @@ class BinOp(expr):
    right: expr
    def __init__(self, left: expr, op: operator, right: expr, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, left: expr = ..., op: operator = ..., right: expr = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class UnaryOp(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("op", "operand")
@@ -610,6 +810,9 @@ class UnaryOp(expr):
    operand: expr
    def __init__(self, op: unaryop, operand: expr, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, op: unaryop = ..., operand: expr = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Lambda(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("args", "body")
@@ -617,6 +820,9 @@ class Lambda(expr):
    body: expr
    def __init__(self, args: arguments, body: expr, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, args: arguments = ..., body: expr = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class IfExp(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("test", "body", "orelse")
@@ -625,6 +831,11 @@ class IfExp(expr):
    orelse: expr
    def __init__(self, test: expr, body: expr, orelse: expr, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, test: expr = ..., body: expr = ..., orelse: expr = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class Dict(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("keys", "values")
@@ -635,6 +846,11 @@ class Dict(expr):
    else:
        def __init__(self, keys: list[expr | None], values: list[expr], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, keys: list[expr | None] = ..., values: list[expr] = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class Set(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("elts",)
@@ -644,6 +860,9 @@ class Set(expr):
    else:
        def __init__(self, elts: list[expr], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, elts: list[expr] = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class ListComp(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("elt", "generators")
@@ -654,6 +873,11 @@ class ListComp(expr):
    else:
        def __init__(self, elt: expr, generators: list[comprehension], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, elt: expr = ..., generators: list[comprehension] = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class SetComp(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("elt", "generators")
@@ -664,6 +888,11 @@ class SetComp(expr):
    else:
        def __init__(self, elt: expr, generators: list[comprehension], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, elt: expr = ..., generators: list[comprehension] = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class DictComp(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("key", "value", "generators")
@@ -677,6 +906,11 @@ class DictComp(expr):
    else:
        def __init__(self, key: expr, value: expr, generators: list[comprehension], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, key: expr = ..., value: expr = ..., generators: list[comprehension] = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class GeneratorExp(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("elt", "generators")
@@ -687,24 +921,38 @@ class GeneratorExp(expr):
    else:
        def __init__(self, elt: expr, generators: list[comprehension], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, elt: expr = ..., generators: list[comprehension] = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class Await(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("value",)
    value: expr
    def __init__(self, value: expr, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, value: expr = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Yield(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("value",)
    value: expr | None
    def __init__(self, value: expr | None = None, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, value: expr | None = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class YieldFrom(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("value",)
    value: expr
    def __init__(self, value: expr, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, value: expr = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Compare(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("left", "ops", "comparators")
@@ -718,6 +966,11 @@ class Compare(expr):
    else:
        def __init__(self, left: expr, ops: list[cmpop], comparators: list[expr], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, left: expr = ..., ops: list[cmpop] = ..., comparators: list[expr] = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class Call(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("func", "args", "keywords")
@@ -731,6 +984,11 @@ class Call(expr):
    else:
        def __init__(self, func: expr, args: list[expr], keywords: list[keyword], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, func: expr = ..., args: list[expr] = ..., keywords: list[keyword] = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class FormattedValue(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("value", "conversion", "format_spec")
@@ -739,6 +997,11 @@ class FormattedValue(expr):
    format_spec: expr | None
    def __init__(self, value: expr, conversion: int, format_spec: expr | None = None, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, value: expr = ..., conversion: int = ..., format_spec: expr | None = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class JoinedStr(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("values",)
@@ -748,6 +1011,9 @@ class JoinedStr(expr):
    else:
        def __init__(self, values: list[expr], **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, values: list[expr] = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Constant(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("value", "kind")
@@ -760,6 +1026,9 @@ class Constant(expr):

    def __init__(self, value: Any, kind: str | None = None, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, value: Any = ..., kind: str | None = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class NamedExpr(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("target", "value")
@@ -767,6 +1036,9 @@ class NamedExpr(expr):
    value: expr
    def __init__(self, target: Name, value: expr, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, target: Name = ..., value: expr = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Attribute(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("value", "attr", "ctx")
@@ -775,6 +1047,11 @@ class Attribute(expr):
    ctx: expr_context  # Not present in Python < 3.13 if not passed to `__init__`
    def __init__(self, value: expr, attr: _Identifier, ctx: expr_context = ..., **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, value: expr = ..., attr: _Identifier = ..., ctx: expr_context = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 if sys.version_info >= (3, 9):
    _Slice: typing_extensions.TypeAlias = expr
    _SliceAttributes: typing_extensions.TypeAlias = _Attributes
@@ -794,6 +1071,16 @@ class Slice(_Slice):
        self, lower: expr | None = None, upper: expr | None = None, step: expr | None = None, **kwargs: Unpack[_SliceAttributes]
    ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            lower: expr | None = ...,
+            upper: expr | None = ...,
+            step: expr | None = ...,
+            **kwargs: Unpack[_SliceAttributes],
+        ) -> Self: ...
+
 if sys.version_info < (3, 9):
    class ExtSlice(slice):
        dims: list[slice]
@@ -811,6 +1098,11 @@ class Subscript(expr):
    ctx: expr_context  # Not present in Python < 3.13 if not passed to `__init__`
    def __init__(self, value: expr, slice: _Slice, ctx: expr_context = ..., **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, value: expr = ..., slice: _Slice = ..., ctx: expr_context = ..., **kwargs: Unpack[_Attributes]
+        ) -> Self: ...
+
 class Starred(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("value", "ctx")
@@ -818,6 +1110,9 @@ class Starred(expr):
    ctx: expr_context  # Not present in Python < 3.13 if not passed to `__init__`
    def __init__(self, value: expr, ctx: expr_context = ..., **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, value: expr = ..., ctx: expr_context = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Name(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("id", "ctx")
@@ -825,6 +1120,9 @@ class Name(expr):
    ctx: expr_context  # Not present in Python < 3.13 if not passed to `__init__`
    def __init__(self, id: _Identifier, ctx: expr_context = ..., **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, id: _Identifier = ..., ctx: expr_context = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class List(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("elts", "ctx")
@@ -835,6 +1133,9 @@ class List(expr):
    else:
        def __init__(self, elts: list[expr], ctx: expr_context = ..., **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, elts: list[expr] = ..., ctx: expr_context = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class Tuple(expr):
    if sys.version_info >= (3, 10):
        __match_args__ = ("elts", "ctx")
@@ -847,6 +1148,9 @@ class Tuple(expr):
    else:
        def __init__(self, elts: list[expr], ctx: expr_context = ..., **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, elts: list[expr] = ..., ctx: expr_context = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class expr_context(AST): ...

 if sys.version_info < (3, 9):
@@ -910,6 +1214,9 @@ class comprehension(AST):
    else:
        def __init__(self, target: expr, iter: expr, ifs: list[expr], is_async: int) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, target: expr = ..., iter: expr = ..., ifs: list[expr] = ..., is_async: int = ...) -> Self: ...
+
 class excepthandler(AST):
    lineno: int
    col_offset: int
@@ -917,6 +1224,11 @@ class excepthandler(AST):
    end_col_offset: int | None
    def __init__(self, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self, *, lineno: int = ..., col_offset: int = ..., end_lineno: int | None = ..., end_col_offset: int | None = ...
+        ) -> Self: ...
+
 class ExceptHandler(excepthandler):
    if sys.version_info >= (3, 10):
        __match_args__ = ("type", "name", "body")
@@ -937,6 +1249,16 @@ class ExceptHandler(excepthandler):
            self, type: expr | None = None, name: _Identifier | None = None, *, body: list[stmt], **kwargs: Unpack[_Attributes]
        ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            type: expr | None = ...,
+            name: _Identifier | None = ...,
+            body: list[stmt] = ...,
+            **kwargs: Unpack[_Attributes],
+        ) -> Self: ...
+
 class arguments(AST):
    if sys.version_info >= (3, 10):
        __match_args__ = ("posonlyargs", "args", "vararg", "kwonlyargs", "kw_defaults", "kwarg", "defaults")
@@ -995,6 +1317,19 @@ class arguments(AST):
            defaults: list[expr],
        ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            posonlyargs: list[arg] = ...,
+            args: list[arg] = ...,
+            vararg: arg | None = ...,
+            kwonlyargs: list[arg] = ...,
+            kw_defaults: list[expr | None] = ...,
+            kwarg: arg | None = ...,
+            defaults: list[expr] = ...,
+        ) -> Self: ...
+
 class arg(AST):
    lineno: int
    col_offset: int
@@ -1009,6 +1344,16 @@ class arg(AST):
        self, arg: _Identifier, annotation: expr | None = None, type_comment: str | None = None, **kwargs: Unpack[_Attributes]
    ) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(
+            self,
+            *,
+            arg: _Identifier = ...,
+            annotation: expr | None = ...,
+            type_comment: str | None = ...,
+            **kwargs: Unpack[_Attributes],
+        ) -> Self: ...
+
 class keyword(AST):
    lineno: int
    col_offset: int
@@ -1023,6 +1368,9 @@ class keyword(AST):
    @overload
    def __init__(self, arg: _Identifier | None = None, *, value: expr, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, arg: _Identifier | None = ..., value: expr = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class alias(AST):
    lineno: int
    col_offset: int
@@ -1034,6 +1382,9 @@ class alias(AST):
    asname: _Identifier | None
    def __init__(self, name: str, asname: _Identifier | None = None, **kwargs: Unpack[_Attributes]) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, name: str = ..., asname: _Identifier | None = ..., **kwargs: Unpack[_Attributes]) -> Self: ...
+
 class withitem(AST):
    if sys.version_info >= (3, 10):
        __match_args__ = ("context_expr", "optional_vars")
@@ -1041,6 +1392,9 @@ class withitem(AST):
    optional_vars: expr | None
    def __init__(self, context_expr: expr, optional_vars: expr | None = None) -> None: ...

+    if sys.version_info >= (3, 14):
+        def __replace__(self, *, context_expr: expr = ..., optional_vars: expr | None = ...) -> Self: ...
+
 if sys.version_info >= (3, 10):
    class Match(stmt):
        __match_args__ = ("subject", "cases")
@@ -1051,6 +1405,11 @@ if sys.version_info >= (3, 10):
        else:
            def __init__(self, subject: expr, cases: list[match_case], **kwargs: Unpack[_Attributes]) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(
+                self, *, subject: expr = ..., cases: list[match_case] = ..., **kwargs: Unpack[_Attributes]
+            ) -> Self: ...
+
    class pattern(AST):
        lineno: int
        col_offset: int
@@ -1058,6 +1417,11 @@ if sys.version_info >= (3, 10):
        end_col_offset: int
        def __init__(self, **kwargs: Unpack[_Attributes[int]]) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(
+                self, *, lineno: int = ..., col_offset: int = ..., end_lineno: int = ..., end_col_offset: int = ...
+            ) -> Self: ...
+
    # Without the alias, Pyright complains variables named pattern are recursively defined
    _Pattern: typing_extensions.TypeAlias = pattern

@@ -1074,16 +1438,25 @@ if sys.version_info >= (3, 10):
            @overload
            def __init__(self, pattern: _Pattern, guard: expr | None = None, *, body: list[stmt]) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(self, *, pattern: _Pattern = ..., guard: expr | None = ..., body: list[stmt] = ...) -> Self: ...
+
    class MatchValue(pattern):
        __match_args__ = ("value",)
        value: expr
        def __init__(self, value: expr, **kwargs: Unpack[_Attributes[int]]) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(self, *, value: expr = ..., **kwargs: Unpack[_Attributes[int]]) -> Self: ...
+
    class MatchSingleton(pattern):
        __match_args__ = ("value",)
        value: Literal[True, False] | None
        def __init__(self, value: Literal[True, False] | None, **kwargs: Unpack[_Attributes[int]]) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(self, *, value: Literal[True, False] | None = ..., **kwargs: Unpack[_Attributes[int]]) -> Self: ...
+
    class MatchSequence(pattern):
        __match_args__ = ("patterns",)
        patterns: list[pattern]
@@ -1092,11 +1465,17 @@ if sys.version_info >= (3, 10):
        else:
            def __init__(self, patterns: list[pattern], **kwargs: Unpack[_Attributes[int]]) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(self, *, patterns: list[pattern] = ..., **kwargs: Unpack[_Attributes[int]]) -> Self: ...
+
    class MatchStar(pattern):
        __match_args__ = ("name",)
        name: _Identifier | None
        def __init__(self, name: _Identifier | None, **kwargs: Unpack[_Attributes[int]]) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(self, *, name: _Identifier | None = ..., **kwargs: Unpack[_Attributes[int]]) -> Self: ...
+
    class MatchMapping(pattern):
        __match_args__ = ("keys", "patterns", "rest")
        keys: list[expr]
@@ -1119,6 +1498,16 @@ if sys.version_info >= (3, 10):
                **kwargs: Unpack[_Attributes[int]],
            ) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(
+                self,
+                *,
+                keys: list[expr] = ...,
+                patterns: list[pattern] = ...,
+                rest: _Identifier | None = ...,
+                **kwargs: Unpack[_Attributes[int]],
+            ) -> Self: ...
+
    class MatchClass(pattern):
        __match_args__ = ("cls", "patterns", "kwd_attrs", "kwd_patterns")
        cls: expr
@@ -1144,6 +1533,17 @@ if sys.version_info >= (3, 10):
                **kwargs: Unpack[_Attributes[int]],
            ) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(
+                self,
+                *,
+                cls: expr = ...,
+                patterns: list[pattern] = ...,
+                kwd_attrs: list[_Identifier] = ...,
+                kwd_patterns: list[pattern] = ...,
+                **kwargs: Unpack[_Attributes[int]],
+            ) -> Self: ...
+
    class MatchAs(pattern):
        __match_args__ = ("pattern", "name")
        pattern: _Pattern | None
@@ -1152,6 +1552,11 @@ if sys.version_info >= (3, 10):
            self, pattern: _Pattern | None = None, name: _Identifier | None = None, **kwargs: Unpack[_Attributes[int]]
        ) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(
+                self, *, pattern: _Pattern | None = ..., name: _Identifier | None = ..., **kwargs: Unpack[_Attributes[int]]
+            ) -> Self: ...
+
    class MatchOr(pattern):
        __match_args__ = ("patterns",)
        patterns: list[pattern]
@@ -1160,6 +1565,9 @@ if sys.version_info >= (3, 10):
        else:
            def __init__(self, patterns: list[pattern], **kwargs: Unpack[_Attributes[int]]) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(self, *, patterns: list[pattern] = ..., **kwargs: Unpack[_Attributes[int]]) -> Self: ...
+
 if sys.version_info >= (3, 12):
    class type_param(AST):
        lineno: int
@@ -1168,6 +1576,9 @@ if sys.version_info >= (3, 12):
        end_col_offset: int
        def __init__(self, **kwargs: Unpack[_Attributes[int]]) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(self, **kwargs: Unpack[_Attributes[int]]) -> Self: ...
+
    class TypeVar(type_param):
        if sys.version_info >= (3, 13):
            __match_args__ = ("name", "bound", "default_value")
@@ -1187,6 +1598,16 @@ if sys.version_info >= (3, 12):
        else:
            def __init__(self, name: _Identifier, bound: expr | None = None, **kwargs: Unpack[_Attributes[int]]) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(
+                self,
+                *,
+                name: _Identifier = ...,
+                bound: expr | None = ...,
+                default_value: expr | None = ...,
+                **kwargs: Unpack[_Attributes[int]],
+            ) -> Self: ...
+
    class ParamSpec(type_param):
        if sys.version_info >= (3, 13):
            __match_args__ = ("name", "default_value")
@@ -1201,6 +1622,11 @@ if sys.version_info >= (3, 12):
        else:
            def __init__(self, name: _Identifier, **kwargs: Unpack[_Attributes[int]]) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(
+                self, *, name: _Identifier = ..., default_value: expr | None = ..., **kwargs: Unpack[_Attributes[int]]
+            ) -> Self: ...
+
    class TypeVarTuple(type_param):
        if sys.version_info >= (3, 13):
            __match_args__ = ("name", "default_value")
@@ -1215,6 +1641,11 @@ if sys.version_info >= (3, 12):
        else:
            def __init__(self, name: _Identifier, **kwargs: Unpack[_Attributes[int]]) -> None: ...

+        if sys.version_info >= (3, 14):
+            def __replace__(
+                self, *, name: _Identifier = ..., default_value: expr | None = ..., **kwargs: Unpack[_Attributes[int]]
+            ) -> Self: ...
+
    class TypeAlias(stmt):
        __match_args__ = ("name", "type_params", "value")
        name: Name
@@ -1233,3 +1664,13 @@ if sys.version_info >= (3, 12):
            def __init__(
                self, name: Name, type_params: list[type_param], value: expr, **kwargs: Unpack[_Attributes[int]]
            ) -> None: ...
+
+        if sys.version_info >= (3, 14):
+            def __replace__(
+                self,
+                *,
+                name: Name = ...,
+                type_params: list[type_param] = ...,
+                value: expr = ...,
+                **kwargs: Unpack[_Attributes[int]],
+            ) -> Self: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/_operator.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/_operator.pyi
@@ -2,7 +2,7 @@ import sys
 from _typeshed import SupportsGetItem
 from collections.abc import Callable, Container, Iterable, MutableMapping, MutableSequence, Sequence
 from typing import Any, AnyStr, Generic, Protocol, SupportsAbs, SupportsIndex, TypeVar, final, overload
-from typing_extensions import ParamSpec, TypeAlias, TypeVarTuple, Unpack
+from typing_extensions import ParamSpec, TypeAlias, TypeIs, TypeVarTuple, Unpack

 _R = TypeVar("_R")
 _T = TypeVar("_T")
@@ -145,3 +145,7 @@ if sys.version_info >= (3, 11):
    def call(obj: Callable[_P, _R], /, *args: _P.args, **kwargs: _P.kwargs) -> _R: ...

 def _compare_digest(a: AnyStr, b: AnyStr, /) -> bool: ...
+
+if sys.version_info >= (3, 14):
+    def is_none(a: object, /) -> TypeIs[None]: ...
+    def is_not_none(a: _T | None, /) -> TypeIs[_T]: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/_stat.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/_stat.pyi
@@ -28,9 +28,9 @@ S_IFDIR: Final = 0o040000

 # These are 0 on systems that don't support the specific kind of file.
 # Example: Linux doesn't support door files, so S_IFDOOR is 0 on linux.
-S_IFDOOR: int
-S_IFPORT: int
-S_IFWHT: int
+S_IFDOOR: Final[int]
+S_IFPORT: Final[int]
+S_IFWHT: Final[int]

 S_ISUID: Final = 0o4000
 S_ISGID: Final = 0o2000
@@ -79,9 +79,9 @@ def S_ISWHT(mode: int, /) -> bool: ...
 def filemode(mode: int, /) -> str: ...

 if sys.platform == "win32":
-    IO_REPARSE_TAG_SYMLINK: int
-    IO_REPARSE_TAG_MOUNT_POINT: int
-    IO_REPARSE_TAG_APPEXECLINK: int
+    IO_REPARSE_TAG_SYMLINK: Final = 0xA000000C
+    IO_REPARSE_TAG_MOUNT_POINT: Final = 0xA0000003
+    IO_REPARSE_TAG_APPEXECLINK: Final = 0x8000001B

 if sys.platform == "win32":
    FILE_ATTRIBUTE_ARCHIVE: Final = 32
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/_thread.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/_thread.pyi
@@ -1,3 +1,4 @@
+import signal
 import sys
 from _typeshed import structseq
 from collections.abc import Callable
@@ -16,16 +17,39 @@ class LockType:
    def acquire(self, blocking: bool = True, timeout: float = -1) -> bool: ...
    def release(self) -> None: ...
    def locked(self) -> bool: ...
+    def acquire_lock(self, blocking: bool = True, timeout: float = -1) -> bool: ...
+    def release_lock(self) -> None: ...
+    def locked_lock(self) -> bool: ...
    def __enter__(self) -> bool: ...
    def __exit__(
        self, type: type[BaseException] | None, value: BaseException | None, traceback: TracebackType | None
    ) -> None: ...

+if sys.version_info >= (3, 13):
+    @final
+    class _ThreadHandle:
+        ident: int
+
+        def join(self, timeout: float | None = None, /) -> None: ...
+        def is_done(self) -> bool: ...
+        def _set_done(self) -> None: ...
+
+    def start_joinable_thread(
+        function: Callable[[], object], handle: _ThreadHandle | None = None, daemon: bool = True
+    ) -> _ThreadHandle: ...
+    lock = LockType
+
@overload
 def start_new_thread(function: Callable[[Unpack[_Ts]], object], args: tuple[Unpack[_Ts]], /) -> int: ...
@overload
 def start_new_thread(function: Callable[..., object], args: tuple[Any, ...], kwargs: dict[str, Any], /) -> int: ...
-def interrupt_main() -> None: ...
+
+if sys.version_info >= (3, 10):
+    def interrupt_main(signum: signal.Signals = ..., /) -> None: ...
+
+else:
+    def interrupt_main() -> None: ...
+
 def exit() -> NoReturn: ...
 def allocate_lock() -> LockType: ...
 def get_ident() -> int: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/_tkinter.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/_tkinter.pyi
@@ -106,8 +106,8 @@ EXCEPTION: Final = 8
 READABLE: Final = 2
 WRITABLE: Final = 4

-TCL_VERSION: str
-TK_VERSION: str
+TCL_VERSION: Final[str]
+TK_VERSION: Final[str]

@final
 class TkttType:
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/builtins.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/builtins.pyi
@@ -33,7 +33,8 @@ from collections.abc import Awaitable, Callable, Iterable, Iterator, MutableSet,
 from io import BufferedRandom, BufferedReader, BufferedWriter, FileIO, TextIOWrapper
 from types import CellType, CodeType, TracebackType

-# mypy crashes if any of {ByteString, Sequence, MutableSequence, Mapping, MutableMapping} are imported from collections.abc in builtins.pyi
+# mypy crashes if any of {ByteString, Sequence, MutableSequence, Mapping, MutableMapping}
+# are imported from collections.abc in builtins.pyi
 from typing import (  # noqa: Y022
    IO,
    Any,
@@ -967,7 +968,9 @@ class tuple(Sequence[_T_co]):
    if sys.version_info >= (3, 9):
        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...

-# Doesn't exist at runtime, but deleting this breaks mypy. See #2999
+# Doesn't exist at runtime, but deleting this breaks mypy and pyright. See:
+# https://github.com/python/typeshed/issues/7580
+# https://github.com/python/mypy/issues/8240
@final
@type_check_only
 class function:
@@ -1084,7 +1087,8 @@ class dict(MutableMapping[_KT, _VT]):
    def keys(self) -> dict_keys[_KT, _VT]: ...
    def values(self) -> dict_values[_KT, _VT]: ...
    def items(self) -> dict_items[_KT, _VT]: ...
-    # Signature of `dict.fromkeys` should be kept identical to `fromkeys` methods of `OrderedDict`/`ChainMap`/`UserDict` in `collections`
+    # Signature of `dict.fromkeys` should be kept identical to
+    # `fromkeys` methods of `OrderedDict`/`ChainMap`/`UserDict` in `collections`
    # TODO: the true signature of `dict.fromkeys` is not expressible in the current type system.
    # See #3800 & https://github.com/python/typing/issues/548#issuecomment-683336963.
    @classmethod
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/cmd.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/cmd.pyi
@@ -1,10 +1,11 @@
 from collections.abc import Callable
 from typing import IO, Any, Final
+from typing_extensions import LiteralString

 __all__ = ["Cmd"]

 PROMPT: Final = "(Cmd) "
-IDENTCHARS: str  # Too big to be `Literal`
+IDENTCHARS: Final[LiteralString]  # Too big to be `Literal`

 class Cmd:
    prompt: str
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/collections/init.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/collections/init.pyi
@@ -345,15 +345,15 @@ class _OrderedDictValuesView(ValuesView[_VT_co], Reversible[_VT_co]):
 # but they are not exposed anywhere)
 # pyright doesn't have a specific error code for subclassing error!
@final
-class _odict_keys(dict_keys[_KT_co, _VT_co], Reversible[_KT_co]):  # type: ignore[misc]  # pyright: ignore
+class _odict_keys(dict_keys[_KT_co, _VT_co], Reversible[_KT_co]):  # type: ignore[misc]  # pyright: ignore[reportGeneralTypeIssues]
    def __reversed__(self) -> Iterator[_KT_co]: ...

@final
-class _odict_items(dict_items[_KT_co, _VT_co], Reversible[tuple[_KT_co, _VT_co]]):  # type: ignore[misc]  # pyright: ignore
+class _odict_items(dict_items[_KT_co, _VT_co], Reversible[tuple[_KT_co, _VT_co]]):  # type: ignore[misc]  # pyright: ignore[reportGeneralTypeIssues]
    def __reversed__(self) -> Iterator[tuple[_KT_co, _VT_co]]: ...

@final
-class _odict_values(dict_values[_KT_co, _VT_co], Reversible[_VT_co], Generic[_KT_co, _VT_co]):  # type: ignore[misc]  # pyright: ignore
+class _odict_values(dict_values[_KT_co, _VT_co], Reversible[_VT_co], Generic[_KT_co, _VT_co]):  # type: ignore[misc]  # pyright: ignore[reportGeneralTypeIssues]
    def __reversed__(self) -> Iterator[_VT_co]: ...

 class OrderedDict(dict[_KT, _VT], Reversible[_KT], Generic[_KT, _VT]):
@@ -475,7 +475,8 @@ class ChainMap(MutableMapping[_KT, _VT]):
    def pop(self, key: _KT, default: _T) -> _VT | _T: ...
    def copy(self) -> Self: ...
    __copy__ = copy
-    # All arguments to `fromkeys` are passed to `dict.fromkeys` at runtime, so the signature should be kept in line with `dict.fromkeys`.
+    # All arguments to `fromkeys` are passed to `dict.fromkeys` at runtime,
+    # so the signature should be kept in line with `dict.fromkeys`.
    @classmethod
    @overload
    def fromkeys(cls, iterable: Iterable[_T]) -> ChainMap[_T, Any | None]: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/crypt.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/crypt.pyi
@@ -1,12 +1,13 @@
 import sys
+from typing import Final

 if sys.platform != "win32":
    class _Method: ...
-    METHOD_CRYPT: _Method
-    METHOD_MD5: _Method
-    METHOD_SHA256: _Method
-    METHOD_SHA512: _Method
-    METHOD_BLOWFISH: _Method
+    METHOD_CRYPT: Final[_Method]
+    METHOD_MD5: Final[_Method]
+    METHOD_SHA256: Final[_Method]
+    METHOD_SHA512: Final[_Method]
+    METHOD_BLOWFISH: Final[_Method]
    methods: list[_Method]
    def mksalt(method: _Method | None = None, *, rounds: int | None = None) -> str: ...
    def crypt(word: str, salt: str | _Method | None = None) -> str: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/ctypes/init.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/ctypes/init.pyi
@@ -185,3 +185,8 @@ if sys.version_info >= (3, 12):
    c_time_t: type[c_int32 | c_int64]  # alias for one or the other at runtime

 class py_object(_CanCastTo, _SimpleCData[_T]): ...
+
+if sys.version_info >= (3, 14):
+    class c_float_complex(_SimpleCData[complex]): ...
+    class c_double_complex(_SimpleCData[complex]): ...
+    class c_longdouble_complex(_SimpleCData[complex]): ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/dataclasses.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/dataclasses.pyi
@@ -229,18 +229,17 @@ if sys.version_info >= (3, 9):
 else:
    class _InitVarMeta(type):
        # Not used, instead `InitVar.__class_getitem__` is called.
-        # pyright ignore is needed because pyright (not unreasonably) thinks this
-        # is an invalid use of InitVar.
-        def __getitem__(self, params: Any) -> InitVar[Any]: ...  # pyright: ignore
+        # pyright (not unreasonably) thinks this is an invalid use of InitVar.
+        def __getitem__(self, params: Any) -> InitVar[Any]: ...  # pyright: ignore[reportInvalidTypeForm]

 class InitVar(Generic[_T], metaclass=_InitVarMeta):
    type: Type[_T]
    def __init__(self, type: Type[_T]) -> None: ...
    if sys.version_info >= (3, 9):
        @overload
-        def __class_getitem__(cls, type: Type[_T]) -> InitVar[_T]: ...  # pyright: ignore
+        def __class_getitem__(cls, type: Type[_T]) -> InitVar[_T]: ...  # pyright: ignore[reportInvalidTypeForm]
        @overload
-        def __class_getitem__(cls, type: Any) -> InitVar[Any]: ...  # pyright: ignore
+        def __class_getitem__(cls, type: Any) -> InitVar[Any]: ...  # pyright: ignore[reportInvalidTypeForm]

 if sys.version_info >= (3, 12):
    def make_dataclass(
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/datetime.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/datetime.pyi
@@ -265,12 +265,12 @@ class datetime(date):
        def fromtimestamp(cls, timestamp: float, /, tz: _TzInfo | None = ...) -> Self: ...

    @classmethod
-    @deprecated("Use timezone-aware objects to represent datetimes in UTC; e.g. by calling .fromtimestamp(datetime.UTC)")
+    @deprecated("Use timezone-aware objects to represent datetimes in UTC; e.g. by calling .fromtimestamp(datetime.timezone.utc)")
    def utcfromtimestamp(cls, t: float, /) -> Self: ...
    @classmethod
    def now(cls, tz: _TzInfo | None = None) -> Self: ...
    @classmethod
-    @deprecated("Use timezone-aware objects to represent datetimes in UTC; e.g. by calling .now(datetime.UTC)")
+    @deprecated("Use timezone-aware objects to represent datetimes in UTC; e.g. by calling .now(datetime.timezone.utc)")
    def utcnow(cls) -> Self: ...
    @classmethod
    def combine(cls, date: _Date, time: _Time, tzinfo: _TzInfo | None = ...) -> Self: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/cmd.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/cmd.pyi
@@ -30,6 +30,7 @@ _CommandT = TypeVar("_CommandT", bound=Command)
 _Ts = TypeVarTuple("_Ts")

 class Command:
+    dry_run: Literal[0, 1]  # Exposed from __getattr_. Same as Distribution.dry_run
    distribution: Distribution
    # Any to work around variance issues
    sub_commands: ClassVar[list[tuple[str, Callable[[Any], bool] | None]]]
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/command/check.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/command/check.pyi
@@ -1,4 +1,4 @@
-from typing import Any, ClassVar, Literal
+from typing import Any, ClassVar, Final, Literal
 from typing_extensions import TypeAlias

 from ..cmd import Command
@@ -22,7 +22,7 @@ class SilentReporter(_Reporter):
    ) -> None: ...
    def system_message(self, level, message, *children, **kwargs): ...

-HAS_DOCUTILS: bool
+HAS_DOCUTILS: Final[bool]

 class check(Command):
    description: str
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/command/config.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/command/config.pyi
@@ -1,12 +1,12 @@
 from _typeshed import StrOrBytesPath
 from collections.abc import Sequence
 from re import Pattern
-from typing import Any, ClassVar, Literal
+from typing import Any, ClassVar, Final, Literal

 from ..ccompiler import CCompiler
 from ..cmd import Command

-LANG_EXT: dict[str, str]
+LANG_EXT: Final[dict[str, str]]

 class config(Command):
    description: str
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/command/install.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/command/install.pyi
@@ -1,11 +1,16 @@
+import sys
 from collections.abc import Callable
-from typing import Any, ClassVar
+from typing import Any, ClassVar, Final, Literal

 from ..cmd import Command

-HAS_USER_SITE: bool
-SCHEME_KEYS: tuple[str, ...]
-INSTALL_SCHEMES: dict[str, dict[Any, Any]]
+HAS_USER_SITE: Final[bool]
+
+SCHEME_KEYS: Final[tuple[Literal["purelib"], Literal["platlib"], Literal["headers"], Literal["scripts"], Literal["data"]]]
+INSTALL_SCHEMES: Final[dict[str, dict[str, str]]]
+
+if sys.version_info < (3, 10):
+    WINDOWS_SCHEME: Final[dict[str, str]]

 class install(Command):
    description: str
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/command/install_lib.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/command/install_lib.pyi
@@ -1,8 +1,8 @@
-from typing import Any, ClassVar
+from typing import Any, ClassVar, Final

 from ..cmd import Command

-PYTHON_SOURCE_EXTENSION: str
+PYTHON_SOURCE_EXTENSION: Final = ".py"

 class install_lib(Command):
    description: str
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/core.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/core.pyi
@@ -3,9 +3,9 @@ from collections.abc import Mapping
 from distutils.cmd import Command as Command
 from distutils.dist import Distribution as Distribution
 from distutils.extension import Extension as Extension
-from typing import Any, Literal
+from typing import Any, Final, Literal

-USAGE: str
+USAGE: Final[str]

 def gen_usage(script_name: StrOrBytesPath) -> str: ...

--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/cygwinccompiler.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/cygwinccompiler.pyi
@@ -1,20 +1,20 @@
 from distutils.unixccompiler import UnixCCompiler
 from distutils.version import LooseVersion
 from re import Pattern
-from typing import Literal
+from typing import Final, Literal

 def get_msvcr() -> list[str] | None: ...

 class CygwinCCompiler(UnixCCompiler): ...
 class Mingw32CCompiler(CygwinCCompiler): ...

-CONFIG_H_OK: str
-CONFIG_H_NOTOK: str
-CONFIG_H_UNCERTAIN: str
+CONFIG_H_OK: Final = "ok"
+CONFIG_H_NOTOK: Final = "not ok"
+CONFIG_H_UNCERTAIN: Final = "uncertain"

 def check_config_h() -> tuple[Literal["ok", "not ok", "uncertain"], str]: ...

-RE_VERSION: Pattern[bytes]
+RE_VERSION: Final[Pattern[bytes]]

 def get_versions() -> tuple[LooseVersion | None, ...]: ...
 def is_cygwingcc() -> bool: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/debug.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/debug.pyi
@@ -1 +1,3 @@
-DEBUG: bool | None
+from typing import Final
+
+DEBUG: Final[str | None]
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/dist.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/dist.pyi
@@ -88,9 +88,9 @@ class Distribution:
    display_options: ClassVar[_OptionsList]
    display_option_names: ClassVar[list[str]]
    negative_opt: ClassVar[dict[str, str]]
-    verbose: int
-    dry_run: int
-    help: int
+    verbose: Literal[0, 1]
+    dry_run: Literal[0, 1]
+    help: Literal[0, 1]
    command_packages: list[str] | None
    script_name: str | None
    script_args: list[str] | None
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/fancy_getopt.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/fancy_getopt.pyi
@@ -1,15 +1,15 @@
 from collections.abc import Iterable, Mapping
 from re import Pattern
-from typing import Any, overload
+from typing import Any, Final, overload
 from typing_extensions import TypeAlias

 _Option: TypeAlias = tuple[str, str | None, str]
 _GR: TypeAlias = tuple[list[str], OptionDummy]

-longopt_pat: str
-longopt_re: Pattern[str]
-neg_alias_re: Pattern[str]
-longopt_xlate: dict[int, int]
+longopt_pat: Final = r"[a-zA-Z](?:[a-zA-Z0-9-]*)"
+longopt_re: Final[Pattern[str]]
+neg_alias_re: Final[Pattern[str]]
+longopt_xlate: Final[dict[int, int]]

 class FancyGetopt:
    def __init__(self, option_table: list[_Option] | None = None) -> None: ...
@@ -25,7 +25,7 @@ def fancy_getopt(
    options: list[_Option], negative_opt: Mapping[_Option, _Option], object: Any, args: list[str] | None
 ) -> list[str] | _GR: ...

-WS_TRANS: dict[int, str]
+WS_TRANS: Final[dict[int, str]]

 def wrap_text(text: str, width: int) -> list[str]: ...
 def translate_longopt(opt: str) -> str: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/log.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/log.pyi
@@ -1,10 +1,10 @@
-from typing import Any
+from typing import Any, Final

-DEBUG: int
-INFO: int
-WARN: int
-ERROR: int
-FATAL: int
+DEBUG: Final = 1
+INFO: Final = 2
+WARN: Final = 3
+ERROR: Final = 4
+FATAL: Final = 5

 class Log:
    def __init__(self, threshold: int = 3) -> None: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/sysconfig.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/distutils/sysconfig.pyi
@@ -1,15 +1,15 @@
 import sys
 from collections.abc import Mapping
 from distutils.ccompiler import CCompiler
-from typing import Literal, overload
+from typing import Final, Literal, overload
 from typing_extensions import deprecated

-PREFIX: str
-EXEC_PREFIX: str
-BASE_PREFIX: str
-BASE_EXEC_PREFIX: str
-project_base: str
-python_build: bool
+PREFIX: Final[str]
+EXEC_PREFIX: Final[str]
+BASE_PREFIX: Final[str]
+BASE_EXEC_PREFIX: Final[str]
+project_base: Final[str]
+python_build: Final[bool]

 def expand_makefile_vars(s: str, vars: Mapping[str, str]) -> str: ...
@overload
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/email/message.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/email/message.pyi
@@ -50,7 +50,8 @@ class Message(Generic[_HeaderT, _HeaderParamT]):
    def get_payload(self, i: None = None, *, decode: Literal[True]) -> _EncodedPayloadType | Any: ...
    @overload  # not multipart, IDEM but w/o kwarg
    def get_payload(self, i: None, decode: Literal[True]) -> _EncodedPayloadType | Any: ...
-    # If `charset=None` and payload supports both `encode` AND `decode`, then an invalid payload could be passed, but this is unlikely
+    # If `charset=None` and payload supports both `encode` AND `decode`,
+    # then an invalid payload could be passed, but this is unlikely
    # Not[_SupportsEncodeToPayload]
    @overload
    def set_payload(
@@ -146,7 +147,11 @@ class Message(Generic[_HeaderT, _HeaderParamT]):
 class MIMEPart(Message[_HeaderRegistryT, _HeaderRegistryParamT]):
    def __init__(self, policy: Policy | None = None) -> None: ...
    def get_body(self, preferencelist: Sequence[str] = ("related", "html", "plain")) -> MIMEPart[_HeaderRegistryT] | None: ...
-    def iter_attachments(self) -> Iterator[MIMEPart[_HeaderRegistryT]]: ...
+    def attach(self, payload: Self) -> None: ...  # type: ignore[override]
+    # The attachments are created via type(self) in the attach method. It's theoretically
+    # possible to sneak other attachment types into a MIMEPart instance, but could cause
+    # cause unforseen consequences.
+    def iter_attachments(self) -> Iterator[Self]: ...
    def iter_parts(self) -> Iterator[MIMEPart[_HeaderRegistryT]]: ...
    def get_content(self, *args: Any, content_manager: ContentManager | None = None, **kw: Any) -> Any: ...
    def set_content(self, *args: Any, content_manager: ContentManager | None = None, **kw: Any) -> None: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/ftplib.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/ftplib.pyi
@@ -86,7 +86,7 @@ class FTP:
    def makeport(self) -> socket: ...
    def makepasv(self) -> tuple[str, int]: ...
    def login(self, user: str = "", passwd: str = "", acct: str = "") -> str: ...
-    # In practice, `rest` rest can actually be anything whose str() is an integer sequence, so to make it simple we allow integers.
+    # In practice, `rest` can actually be anything whose str() is an integer sequence, so to make it simple we allow integers
    def ntransfercmd(self, cmd: str, rest: int | str | None = None) -> tuple[socket, int | None]: ...
    def transfercmd(self, cmd: str, rest: int | str | None = None) -> socket: ...
    def retrbinary(
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/json/encoder.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/json/encoder.pyi
@@ -1,12 +1,12 @@
 from collections.abc import Callable, Iterator
 from re import Pattern
-from typing import Any
+from typing import Any, Final

-ESCAPE: Pattern[str]
-ESCAPE_ASCII: Pattern[str]
-HAS_UTF8: Pattern[bytes]
-ESCAPE_DCT: dict[str, str]
-INFINITY: float
+ESCAPE: Final[Pattern[str]]
+ESCAPE_ASCII: Final[Pattern[str]]
+HAS_UTF8: Final[Pattern[bytes]]
+ESCAPE_DCT: Final[dict[str, str]]
+INFINITY: Final[float]

 def py_encode_basestring(s: str) -> str: ...  # undocumented
 def py_encode_basestring_ascii(s: str) -> str: ...  # undocumented
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/operator.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/operator.pyi
@@ -61,6 +61,9 @@ __all__ = [
 if sys.version_info >= (3, 11):
    __all__ += ["call"]

+if sys.version_info >= (3, 14):
+    __all__ += ["is_none", "is_not_none"]
+
 __lt__ = lt
 __le__ = le
 __eq__ = eq
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/os/init.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/os/init.pyi
@@ -365,7 +365,9 @@ class stat_result(structseq[float], tuple[int, int, int, int, int, int, int, flo
    if sys.version_info >= (3, 12) and sys.platform == "win32":
        @property
        @deprecated(
-            "Use st_birthtime instead to retrieve the file creation time. In the future, this property will contain the last metadata change time."
+            """\
+Use st_birthtime instead to retrieve the file creation time. \
+In the future, this property will contain the last metadata change time."""
        )
        def st_ctime(self) -> float: ...
    else:
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/poplib.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/poplib.pyi
@@ -67,5 +67,6 @@ class POP3_SSL(POP3):
            timeout: float = ...,
            context: ssl.SSLContext | None = None,
        ) -> None: ...
-        # "context" is actually the last argument, but that breaks LSP and it doesn't really matter because all the arguments are ignored
+        # "context" is actually the last argument,
+        # but that breaks LSP and it doesn't really matter because all the arguments are ignored
        def stls(self, context: Any = None, keyfile: Any = None, certfile: Any = None) -> NoReturn: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/pyexpat/init.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/pyexpat/init.pyi
@@ -15,9 +15,9 @@ class ExpatError(Exception):
    offset: int

 error = ExpatError
-XML_PARAM_ENTITY_PARSING_NEVER: int
-XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE: int
-XML_PARAM_ENTITY_PARSING_ALWAYS: int
+XML_PARAM_ENTITY_PARSING_NEVER: Final = 0
+XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE: Final = 1
+XML_PARAM_ENTITY_PARSING_ALWAYS: Final = 2

 _Model: TypeAlias = tuple[int, int, str | None, tuple[Any, ...]]

--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/pyexpat/errors.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/pyexpat/errors.pyi
@@ -1,49 +1,51 @@
 import sys
+from typing import Final
+from typing_extensions import LiteralString

 codes: dict[str, int]
 messages: dict[int, str]

-XML_ERROR_ABORTED: str
-XML_ERROR_ASYNC_ENTITY: str
-XML_ERROR_ATTRIBUTE_EXTERNAL_ENTITY_REF: str
-XML_ERROR_BAD_CHAR_REF: str
-XML_ERROR_BINARY_ENTITY_REF: str
-XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING: str
-XML_ERROR_DUPLICATE_ATTRIBUTE: str
-XML_ERROR_ENTITY_DECLARED_IN_PE: str
-XML_ERROR_EXTERNAL_ENTITY_HANDLING: str
-XML_ERROR_FEATURE_REQUIRES_XML_DTD: str
-XML_ERROR_FINISHED: str
-XML_ERROR_INCOMPLETE_PE: str
-XML_ERROR_INCORRECT_ENCODING: str
-XML_ERROR_INVALID_TOKEN: str
-XML_ERROR_JUNK_AFTER_DOC_ELEMENT: str
-XML_ERROR_MISPLACED_XML_PI: str
-XML_ERROR_NOT_STANDALONE: str
-XML_ERROR_NOT_SUSPENDED: str
-XML_ERROR_NO_ELEMENTS: str
-XML_ERROR_NO_MEMORY: str
-XML_ERROR_PARAM_ENTITY_REF: str
-XML_ERROR_PARTIAL_CHAR: str
-XML_ERROR_PUBLICID: str
-XML_ERROR_RECURSIVE_ENTITY_REF: str
-XML_ERROR_SUSPENDED: str
-XML_ERROR_SUSPEND_PE: str
-XML_ERROR_SYNTAX: str
-XML_ERROR_TAG_MISMATCH: str
-XML_ERROR_TEXT_DECL: str
-XML_ERROR_UNBOUND_PREFIX: str
-XML_ERROR_UNCLOSED_CDATA_SECTION: str
-XML_ERROR_UNCLOSED_TOKEN: str
-XML_ERROR_UNDECLARING_PREFIX: str
-XML_ERROR_UNDEFINED_ENTITY: str
-XML_ERROR_UNEXPECTED_STATE: str
-XML_ERROR_UNKNOWN_ENCODING: str
-XML_ERROR_XML_DECL: str
+XML_ERROR_ABORTED: Final[LiteralString]
+XML_ERROR_ASYNC_ENTITY: Final[LiteralString]
+XML_ERROR_ATTRIBUTE_EXTERNAL_ENTITY_REF: Final[LiteralString]
+XML_ERROR_BAD_CHAR_REF: Final[LiteralString]
+XML_ERROR_BINARY_ENTITY_REF: Final[LiteralString]
+XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING: Final[LiteralString]
+XML_ERROR_DUPLICATE_ATTRIBUTE: Final[LiteralString]
+XML_ERROR_ENTITY_DECLARED_IN_PE: Final[LiteralString]
+XML_ERROR_EXTERNAL_ENTITY_HANDLING: Final[LiteralString]
+XML_ERROR_FEATURE_REQUIRES_XML_DTD: Final[LiteralString]
+XML_ERROR_FINISHED: Final[LiteralString]
+XML_ERROR_INCOMPLETE_PE: Final[LiteralString]
+XML_ERROR_INCORRECT_ENCODING: Final[LiteralString]
+XML_ERROR_INVALID_TOKEN: Final[LiteralString]
+XML_ERROR_JUNK_AFTER_DOC_ELEMENT: Final[LiteralString]
+XML_ERROR_MISPLACED_XML_PI: Final[LiteralString]
+XML_ERROR_NOT_STANDALONE: Final[LiteralString]
+XML_ERROR_NOT_SUSPENDED: Final[LiteralString]
+XML_ERROR_NO_ELEMENTS: Final[LiteralString]
+XML_ERROR_NO_MEMORY: Final[LiteralString]
+XML_ERROR_PARAM_ENTITY_REF: Final[LiteralString]
+XML_ERROR_PARTIAL_CHAR: Final[LiteralString]
+XML_ERROR_PUBLICID: Final[LiteralString]
+XML_ERROR_RECURSIVE_ENTITY_REF: Final[LiteralString]
+XML_ERROR_SUSPENDED: Final[LiteralString]
+XML_ERROR_SUSPEND_PE: Final[LiteralString]
+XML_ERROR_SYNTAX: Final[LiteralString]
+XML_ERROR_TAG_MISMATCH: Final[LiteralString]
+XML_ERROR_TEXT_DECL: Final[LiteralString]
+XML_ERROR_UNBOUND_PREFIX: Final[LiteralString]
+XML_ERROR_UNCLOSED_CDATA_SECTION: Final[LiteralString]
+XML_ERROR_UNCLOSED_TOKEN: Final[LiteralString]
+XML_ERROR_UNDECLARING_PREFIX: Final[LiteralString]
+XML_ERROR_UNDEFINED_ENTITY: Final[LiteralString]
+XML_ERROR_UNEXPECTED_STATE: Final[LiteralString]
+XML_ERROR_UNKNOWN_ENCODING: Final[LiteralString]
+XML_ERROR_XML_DECL: Final[LiteralString]
 if sys.version_info >= (3, 11):
-    XML_ERROR_RESERVED_PREFIX_XML: str
-    XML_ERROR_RESERVED_PREFIX_XMLNS: str
-    XML_ERROR_RESERVED_NAMESPACE_URI: str
-    XML_ERROR_INVALID_ARGUMENT: str
-    XML_ERROR_NO_BUFFER: str
-    XML_ERROR_AMPLIFICATION_LIMIT_BREACH: str
+    XML_ERROR_RESERVED_PREFIX_XML: Final[LiteralString]
+    XML_ERROR_RESERVED_PREFIX_XMLNS: Final[LiteralString]
+    XML_ERROR_RESERVED_NAMESPACE_URI: Final[LiteralString]
+    XML_ERROR_INVALID_ARGUMENT: Final[LiteralString]
+    XML_ERROR_NO_BUFFER: Final[LiteralString]
+    XML_ERROR_AMPLIFICATION_LIMIT_BREACH: Final[LiteralString]
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/pyexpat/model.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/pyexpat/model.pyi
@@ -1,11 +1,13 @@
-XML_CTYPE_ANY: int
-XML_CTYPE_CHOICE: int
-XML_CTYPE_EMPTY: int
-XML_CTYPE_MIXED: int
-XML_CTYPE_NAME: int
-XML_CTYPE_SEQ: int
+from typing import Final

-XML_CQUANT_NONE: int
-XML_CQUANT_OPT: int
-XML_CQUANT_PLUS: int
-XML_CQUANT_REP: int
+XML_CTYPE_ANY: Final = 2
+XML_CTYPE_EMPTY: Final = 1
+XML_CTYPE_MIXED: Final = 3
+XML_CTYPE_NAME: Final = 4
+XML_CTYPE_CHOICE: Final = 5
+XML_CTYPE_SEQ: Final = 6
+
+XML_CQUANT_NONE: Final = 0
+XML_CQUANT_OPT: Final = 1
+XML_CQUANT_REP: Final = 2
+XML_CQUANT_PLUS: Final = 3
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/socketserver.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/socketserver.pyi
@@ -3,8 +3,9 @@ import types
 from _socket import _Address, _RetAddress
 from _typeshed import ReadableBuffer
 from collections.abc import Callable
+from io import BufferedIOBase
 from socket import socket as _socket
-from typing import Any, BinaryIO, ClassVar
+from typing import Any, ClassVar
 from typing_extensions import Self, TypeAlias

 __all__ = [
@@ -158,11 +159,11 @@ class StreamRequestHandler(BaseRequestHandler):
    timeout: ClassVar[float | None]  # undocumented
    disable_nagle_algorithm: ClassVar[bool]  # undocumented
    connection: Any  # undocumented
-    rfile: BinaryIO
-    wfile: BinaryIO
+    rfile: BufferedIOBase
+    wfile: BufferedIOBase

 class DatagramRequestHandler(BaseRequestHandler):
-    packet: _socket  # undocumented
+    packet: bytes  # undocumented
    socket: _socket  # undocumented
-    rfile: BinaryIO
-    wfile: BinaryIO
+    rfile: BufferedIOBase
+    wfile: BufferedIOBase
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/tkinter/constants.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/tkinter/constants.pyi
@@ -1,12 +1,12 @@
 from typing import Final

 # These are not actually bools. See #4669
-NO: bool
-YES: bool
-TRUE: bool
-FALSE: bool
-ON: bool
-OFF: bool
+NO: Final[bool]
+YES: Final[bool]
+TRUE: Final[bool]
+FALSE: Final[bool]
+ON: Final[bool]
+OFF: Final[bool]
 N: Final = "n"
 S: Final = "s"
 W: Final = "w"
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/tkinter/dialog.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/tkinter/dialog.pyi
@@ -2,12 +2,12 @@ import sys
 from _typeshed import Incomplete
 from collections.abc import Mapping
 from tkinter import Widget
-from typing import Any
+from typing import Any, Final

 if sys.version_info >= (3, 9):
    __all__ = ["Dialog"]

-DIALOG_ICON: str
+DIALOG_ICON: Final = "questhead"

 class Dialog(Widget):
    widgetName: str
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/tkinter/messagebox.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/tkinter/messagebox.pyi
@@ -1,6 +1,6 @@
 import sys
 from tkinter.commondialog import Dialog
-from typing import ClassVar
+from typing import ClassVar, Final

 if sys.version_info >= (3, 9):
    __all__ = [
@@ -14,22 +14,22 @@ if sys.version_info >= (3, 9):
        "askretrycancel",
    ]

-ERROR: str
-INFO: str
-QUESTION: str
-WARNING: str
-ABORTRETRYIGNORE: str
-OK: str
-OKCANCEL: str
-RETRYCANCEL: str
-YESNO: str
-YESNOCANCEL: str
-ABORT: str
-RETRY: str
-IGNORE: str
-CANCEL: str
-YES: str
-NO: str
+ERROR: Final = "error"
+INFO: Final = "info"
+QUESTION: Final = "question"
+WARNING: Final = "warning"
+ABORTRETRYIGNORE: Final = "abortretryignore"
+OK: Final = "ok"
+OKCANCEL: Final = "okcancel"
+RETRYCANCEL: Final = "retrycancel"
+YESNO: Final = "yesno"
+YESNOCANCEL: Final = "yesnocancel"
+ABORT: Final = "abort"
+RETRY: Final = "retry"
+IGNORE: Final = "ignore"
+CANCEL: Final = "cancel"
+YES: Final = "yes"
+NO: Final = "no"

 class Message(Dialog):
    command: ClassVar[str]
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/tkinter/ttk.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/tkinter/ttk.pyi
@@ -556,7 +556,9 @@ class Notebook(Widget):
        sticky: str = ...,  # consists of letters 'n', 's', 'w', 'e', no repeats, may be empty
        padding: _Padding = ...,
        text: str = ...,
-        image=...,  # Sequence of an image name, followed by zero or more (sequences of one or more state names followed by an image name)
+        # `image` is a sequence of an image name, followed by zero or more
+        # (sequences of one or more state names followed by an image name)
+        image=...,
        compound: tkinter._Compound = ...,
        underline: int = ...,
    ) -> None: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/typing.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/typing.pyi
@@ -2,7 +2,7 @@
 # ruff: noqa: F811
 # TODO: The collections import is required, otherwise mypy crashes.
 # https://github.com/python/mypy/issues/16744
-import collections  # noqa: F401  # pyright: ignore
+import collections  # noqa: F401  # pyright: ignore[reportUnusedImport]
 import sys
 import typing_extensions
 from _collections_abc import dict_items, dict_keys, dict_values
@@ -800,18 +800,12 @@ class IO(Iterator[AnyStr]):
    def writable(self) -> bool: ...
    @abstractmethod
    @overload
-    def write(self: IO[str], s: str, /) -> int: ...
-    @abstractmethod
-    @overload
    def write(self: IO[bytes], s: ReadableBuffer, /) -> int: ...
    @abstractmethod
    @overload
    def write(self, s: AnyStr, /) -> int: ...
    @abstractmethod
    @overload
-    def writelines(self: IO[str], lines: Iterable[str], /) -> None: ...
-    @abstractmethod
-    @overload
    def writelines(self: IO[bytes], lines: Iterable[ReadableBuffer], /) -> None: ...
    @abstractmethod
    @overload
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/unittest/runner.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/unittest/runner.pyi
@@ -2,36 +2,52 @@ import sys
 import unittest.case
 import unittest.result
 import unittest.suite
-from _typeshed import Incomplete
+from _typeshed import SupportsFlush, SupportsWrite
 from collections.abc import Callable, Iterable
-from typing import TextIO
-from typing_extensions import TypeAlias
+from typing import Any, Generic, Protocol, TypeVar
+from typing_extensions import Never, TypeAlias

-_ResultClassType: TypeAlias = Callable[[TextIO, bool, int], unittest.result.TestResult]
+_ResultClassType: TypeAlias = Callable[[_TextTestStream, bool, int], TextTestResult]

-class TextTestResult(unittest.result.TestResult):
+class _SupportsWriteAndFlush(SupportsWrite[str], SupportsFlush, Protocol): ...
+
+# All methods used by unittest.runner.TextTestResult's stream
+class _TextTestStream(_SupportsWriteAndFlush, Protocol):
+    def writeln(self, arg: str | None = None) -> str: ...
+
+# _WritelnDecorator should have all the same attrs as its stream param.
+# But that's not feasible to do Generically
+# We can expand the attributes if requested
+class _WritelnDecorator(_TextTestStream):
+    def __init__(self, stream: _TextTestStream) -> None: ...
+    def __getattr__(self, attr: str) -> Any: ...  # Any attribute from the stream type passed to __init__
+    # These attributes are prevented by __getattr__
+    stream: Never
+    __getstate__: Never
+
+_StreamT = TypeVar("_StreamT", bound=_TextTestStream, default=_WritelnDecorator)
+
+class TextTestResult(unittest.result.TestResult, Generic[_StreamT]):
    descriptions: bool  # undocumented
    dots: bool  # undocumented
    separator1: str
    separator2: str
    showAll: bool  # undocumented
-    stream: TextIO  # undocumented
+    stream: _StreamT  # undocumented
    if sys.version_info >= (3, 12):
        durations: unittest.result._DurationsType | None
        def __init__(
-            self, stream: TextIO, descriptions: bool, verbosity: int, *, durations: unittest.result._DurationsType | None = None
+            self, stream: _StreamT, descriptions: bool, verbosity: int, *, durations: unittest.result._DurationsType | None = None
        ) -> None: ...
    else:
-        def __init__(self, stream: TextIO, descriptions: bool, verbosity: int) -> None: ...
+        def __init__(self, stream: _StreamT, descriptions: bool, verbosity: int) -> None: ...

    def getDescription(self, test: unittest.case.TestCase) -> str: ...
    def printErrorList(self, flavour: str, errors: Iterable[tuple[unittest.case.TestCase, str]]) -> None: ...

 class TextTestRunner:
    resultclass: _ResultClassType
-    # TODO: add `_WritelnDecorator` type
-    # stream: _WritelnDecorator
-    stream: Incomplete
+    stream: _WritelnDecorator
    descriptions: bool
    verbosity: int
    failfast: bool
@@ -43,7 +59,7 @@ class TextTestRunner:
        durations: unittest.result._DurationsType | None
        def __init__(
            self,
-            stream: TextIO | None = None,
+            stream: _SupportsWriteAndFlush | None = None,
            descriptions: bool = True,
            verbosity: int = 1,
            failfast: bool = False,
@@ -57,7 +73,7 @@ class TextTestRunner:
    else:
        def __init__(
            self,
-            stream: TextIO | None = None,
+            stream: _SupportsWriteAndFlush | None = None,
            descriptions: bool = True,
            verbosity: int = 1,
            failfast: bool = False,
@@ -68,5 +84,5 @@ class TextTestRunner:
            tb_locals: bool = False,
        ) -> None: ...

-    def _makeResult(self) -> unittest.result.TestResult: ...
-    def run(self, test: unittest.suite.TestSuite | unittest.case.TestCase) -> unittest.result.TestResult: ...
+    def _makeResult(self) -> TextTestResult: ...
+    def run(self, test: unittest.suite.TestSuite | unittest.case.TestCase) -> TextTestResult: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/zipfile/init.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/zipfile/init.pyi
@@ -304,6 +304,7 @@ else:

    class Path:
        root: CompleteDirs
+        at: str
        def __init__(self, root: ZipFile | StrPath | IO[bytes], at: str = "") -> None: ...
        @property
        def name(self) -> str: ...
--- a/crates/red_knot_python_semantic/vendor/typeshed/stdlib/zipfile/_path.pyi
+++ b/crates/red_knot_python_semantic/vendor/typeshed/stdlib/zipfile/_path.pyi
@@ -31,6 +31,7 @@ if sys.version_info >= (3, 12):

    class Path:
        root: CompleteDirs
+        at: str
        def __init__(self, root: ZipFile | StrPath | IO[bytes], at: str = "") -> None: ...
        @property
        def name(self) -> str: ...
--- a/crates/red_knot_server/src/server.rs
+++ b/crates/red_knot_server/src/server.rs
@@ -3,11 +3,11 @@
 use std::num::NonZeroUsize;
 use std::panic::PanicInfo;

-use lsp_server as lsp;
-use lsp_types as types;
+use lsp_server::Message;
 use lsp_types::{
-    ClientCapabilities, DiagnosticOptions, NotebookCellSelector, NotebookDocumentSyncOptions,
-    NotebookSelector, TextDocumentSyncCapability, TextDocumentSyncOptions,
+    ClientCapabilities, DiagnosticOptions, DiagnosticServerCapabilities, MessageType,
+    ServerCapabilities, TextDocumentSyncCapability, TextDocumentSyncKind, TextDocumentSyncOptions,
+    Url,
 };

 use self::connection::{Connection, ConnectionInitializer};
@@ -74,7 +74,7 @@ impl Server {
            init_params.client_info.as_ref(),
        );

-        let mut workspace_for_url = |url: lsp_types::Url| {
+        let mut workspace_for_url = |url: Url| {
            let Some(workspace_settings) = workspace_settings.as_mut() else {
                return (url, ClientSettings::default());
            };
@@ -93,13 +93,18 @@ impl Server {
            }).collect())
            .or_else(|| {
                tracing::warn!("No workspace(s) were provided during initialization. Using the current working directory as a default workspace...");
-                let uri = types::Url::from_file_path(std::env::current_dir().ok()?).ok()?;
+                let uri = Url::from_file_path(std::env::current_dir().ok()?).ok()?;
                Some(vec![workspace_for_url(uri)])
            })
            .ok_or_else(|| {
                anyhow::anyhow!("Failed to get the current working directory while creating a default workspace.")
            })?;

+        if workspaces.len() > 1 {
+            // TODO(dhruvmanila): Support multi-root workspaces
+            anyhow::bail!("Multi-root workspaces are not supported yet");
+        }
+
        Ok(Self {
            connection,
            worker_threads,
@@ -149,7 +154,7 @@ impl Server {
            try_show_message(
                "The Ruff language server exited with a panic. See the logs for more details."
                    .to_string(),
-                lsp_types::MessageType::ERROR,
+                MessageType::ERROR,
            )
            .ok();
        }));
@@ -182,9 +187,9 @@ impl Server {
                break;
            }
            let task = match msg {
-                lsp::Message::Request(req) => api::request(req),
-                lsp::Message::Notification(notification) => api::notification(notification),
-                lsp::Message::Response(response) => scheduler.response(response),
+                Message::Request(req) => api::request(req),
+                Message::Notification(notification) => api::notification(notification),
+                Message::Response(response) => scheduler.response(response),
            };
            scheduler.dispatch(task);
        }
@@ -206,28 +211,17 @@ impl Server {
            .unwrap_or_default()
    }

-    fn server_capabilities(position_encoding: PositionEncoding) -> types::ServerCapabilities {
-        types::ServerCapabilities {
+    fn server_capabilities(position_encoding: PositionEncoding) -> ServerCapabilities {
+        ServerCapabilities {
            position_encoding: Some(position_encoding.into()),
-            diagnostic_provider: Some(types::DiagnosticServerCapabilities::Options(
-                DiagnosticOptions {
-                    identifier: Some(crate::DIAGNOSTIC_NAME.into()),
-                    ..Default::default()
-                },
-            )),
-            notebook_document_sync: Some(types::OneOf::Left(NotebookDocumentSyncOptions {
-                save: Some(false),
-                notebook_selector: [NotebookSelector::ByCells {
-                    notebook: None,
-                    cells: vec![NotebookCellSelector {
-                        language: "python".to_string(),
-                    }],
-                }]
-                .to_vec(),
+            diagnostic_provider: Some(DiagnosticServerCapabilities::Options(DiagnosticOptions {
+                identifier: Some(crate::DIAGNOSTIC_NAME.into()),
+                ..Default::default()
            })),
            text_document_sync: Some(TextDocumentSyncCapability::Options(
                TextDocumentSyncOptions {
                    open_close: Some(true),
+                    change: Some(TextDocumentSyncKind::INCREMENTAL),
                    ..Default::default()
                },
            )),
--- a/crates/red_knot_server/src/server/api.rs
+++ b/crates/red_knot_server/src/server/api.rs
@@ -1,13 +1,15 @@
-use crate::{server::schedule::Task, session::Session, system::url_to_system_path};
 use lsp_server as server;

+use crate::server::schedule::Task;
+use crate::session::Session;
+use crate::system::{url_to_any_system_path, AnySystemPath};
+
 mod diagnostics;
 mod notifications;
 mod requests;
 mod traits;

 use notifications as notification;
-use red_knot_workspace::db::RootDatabase;
 use requests as request;

 use self::traits::{NotificationHandler, RequestHandler};
@@ -43,6 +45,7 @@ pub(super) fn notification<'a>(notif: server::Notification) -> Task<'a> {
    match notif.method.as_str() {
        notification::DidCloseTextDocumentHandler::METHOD => local_notification_task::<notification::DidCloseTextDocumentHandler>(notif),
        notification::DidOpenTextDocumentHandler::METHOD => local_notification_task::<notification::DidOpenTextDocumentHandler>(notif),
+        notification::DidChangeTextDocumentHandler::METHOD => local_notification_task::<notification::DidChangeTextDocumentHandler>(notif),
        notification::DidOpenNotebookHandler::METHOD => {
            local_notification_task::<notification::DidOpenNotebookHandler>(notif)
        }
@@ -82,12 +85,18 @@ fn background_request_task<'a, R: traits::BackgroundDocumentRequestHandler>(
    Ok(Task::background(schedule, move |session: &Session| {
        let url = R::document_url(&params).into_owned();

-        let Ok(path) = url_to_system_path(&url) else {
+        let Ok(path) = url_to_any_system_path(&url) else {
            return Box::new(|_, _| {});
        };
-        let db = session
-            .workspace_db_for_path(path.as_std_path())
-            .map(RootDatabase::snapshot);
+        let db = match path {
+            AnySystemPath::System(path) => {
+                match session.workspace_db_for_path(path.as_std_path()) {
+                    Some(db) => db.snapshot(),
+                    None => session.default_workspace_db().snapshot(),
+                }
+            }
+            AnySystemPath::SystemVirtual(_) => session.default_workspace_db().snapshot(),
+        };

        let Some(snapshot) = session.take_snapshot(url) else {
            return Box::new(|_, _| {});
--- a/crates/red_knot_server/src/server/api/notifications.rs
+++ b/crates/red_knot_server/src/server/api/notifications.rs
@@ -1,9 +1,11 @@
+mod did_change;
 mod did_close;
 mod did_close_notebook;
 mod did_open;
 mod did_open_notebook;
 mod set_trace;

+pub(super) use did_change::DidChangeTextDocumentHandler;
 pub(super) use did_close::DidCloseTextDocumentHandler;
 pub(super) use did_close_notebook::DidCloseNotebookHandler;
 pub(super) use did_open::DidOpenTextDocumentHandler;
--- a/crates/red_knot_server/src/server/api/notifications/did_change.rs
+++ b/crates/red_knot_server/src/server/api/notifications/did_change.rs
@@ -0,0 +1,55 @@
+use lsp_server::ErrorCode;
+use lsp_types::notification::DidChangeTextDocument;
+use lsp_types::DidChangeTextDocumentParams;
+
+use red_knot_workspace::watch::ChangeEvent;
+
+use crate::server::api::traits::{NotificationHandler, SyncNotificationHandler};
+use crate::server::api::LSPResult;
+use crate::server::client::{Notifier, Requester};
+use crate::server::Result;
+use crate::session::Session;
+use crate::system::{url_to_any_system_path, AnySystemPath};
+
+pub(crate) struct DidChangeTextDocumentHandler;
+
+impl NotificationHandler for DidChangeTextDocumentHandler {
+    type NotificationType = DidChangeTextDocument;
+}
+
+impl SyncNotificationHandler for DidChangeTextDocumentHandler {
+    fn run(
+        session: &mut Session,
+        _notifier: Notifier,
+        _requester: &mut Requester,
+        params: DidChangeTextDocumentParams,
+    ) -> Result<()> {
+        let Ok(path) = url_to_any_system_path(&params.text_document.uri) else {
+            return Ok(());
+        };
+
+        let key = session.key_from_url(params.text_document.uri);
+
+        session
+            .update_text_document(&key, params.content_changes, params.text_document.version)
+            .with_failure_code(ErrorCode::InternalError)?;
+
+        match path {
+            AnySystemPath::System(path) => {
+                let db = match session.workspace_db_for_path_mut(path.as_std_path()) {
+                    Some(db) => db,
+                    None => session.default_workspace_db_mut(),
+                };
+                db.apply_changes(vec![ChangeEvent::file_content_changed(path)], None);
+            }
+            AnySystemPath::SystemVirtual(virtual_path) => {
+                let db = session.default_workspace_db_mut();
+                db.apply_changes(vec![ChangeEvent::ChangedVirtual(virtual_path)], None);
+            }
+        }
+
+        // TODO(dhruvmanila): Publish diagnostics if the client doesnt support pull diagnostics
+
+        Ok(())
+    }
+}
--- a/crates/red_knot_server/src/server/api/notifications/did_close.rs
+++ b/crates/red_knot_server/src/server/api/notifications/did_close.rs
@@ -1,8 +1,7 @@
 use lsp_server::ErrorCode;
 use lsp_types::notification::DidCloseTextDocument;
 use lsp_types::DidCloseTextDocumentParams;
-
-use ruff_db::files::File;
+use red_knot_workspace::watch::ChangeEvent;

 use crate::server::api::diagnostics::clear_diagnostics;
 use crate::server::api::traits::{NotificationHandler, SyncNotificationHandler};
@@ -10,7 +9,7 @@ use crate::server::api::LSPResult;
 use crate::server::client::{Notifier, Requester};
 use crate::server::Result;
 use crate::session::Session;
-use crate::system::url_to_system_path;
+use crate::system::{url_to_any_system_path, AnySystemPath};

 pub(crate) struct DidCloseTextDocumentHandler;

@@ -25,7 +24,7 @@ impl SyncNotificationHandler for DidCloseTextDocumentHandler {
        _requester: &mut Requester,
        params: DidCloseTextDocumentParams,
    ) -> Result<()> {
-        let Ok(path) = url_to_system_path(&params.text_document.uri) else {
+        let Ok(path) = url_to_any_system_path(&params.text_document.uri) else {
            return Ok(());
        };

@@ -34,8 +33,9 @@ impl SyncNotificationHandler for DidCloseTextDocumentHandler {
            .close_document(&key)
            .with_failure_code(ErrorCode::InternalError)?;

-        if let Some(db) = session.workspace_db_for_path_mut(path.as_std_path()) {
-            File::sync_path(db, &path);
+        if let AnySystemPath::SystemVirtual(virtual_path) = path {
+            let db = session.default_workspace_db_mut();
+            db.apply_changes(vec![ChangeEvent::DeletedVirtual(virtual_path)], None);
        }

        clear_diagnostics(key.url(), &notifier)?;
--- a/crates/red_knot_server/src/server/api/notifications/did_close_notebook.rs
+++ b/crates/red_knot_server/src/server/api/notifications/did_close_notebook.rs
@@ -1,14 +1,14 @@
 use lsp_types::notification::DidCloseNotebookDocument;
 use lsp_types::DidCloseNotebookDocumentParams;

-use ruff_db::files::File;
+use red_knot_workspace::watch::ChangeEvent;

 use crate::server::api::traits::{NotificationHandler, SyncNotificationHandler};
 use crate::server::api::LSPResult;
 use crate::server::client::{Notifier, Requester};
 use crate::server::Result;
 use crate::session::Session;
-use crate::system::url_to_system_path;
+use crate::system::{url_to_any_system_path, AnySystemPath};

 pub(crate) struct DidCloseNotebookHandler;

@@ -23,7 +23,7 @@ impl SyncNotificationHandler for DidCloseNotebookHandler {
        _requester: &mut Requester,
        params: DidCloseNotebookDocumentParams,
    ) -> Result<()> {
-        let Ok(path) = url_to_system_path(&params.notebook_document.uri) else {
+        let Ok(path) = url_to_any_system_path(&params.notebook_document.uri) else {
            return Ok(());
        };

@@ -32,8 +32,9 @@ impl SyncNotificationHandler for DidCloseNotebookHandler {
            .close_document(&key)
            .with_failure_code(lsp_server::ErrorCode::InternalError)?;

-        if let Some(db) = session.workspace_db_for_path_mut(path.as_std_path()) {
-            File::sync_path(db, &path);
+        if let AnySystemPath::SystemVirtual(virtual_path) = path {
+            let db = session.default_workspace_db_mut();
+            db.apply_changes(vec![ChangeEvent::DeletedVirtual(virtual_path)], None);
        }

        Ok(())
--- a/crates/red_knot_server/src/server/api/notifications/did_open.rs
+++ b/crates/red_knot_server/src/server/api/notifications/did_open.rs
@@ -1,13 +1,14 @@
 use lsp_types::notification::DidOpenTextDocument;
 use lsp_types::DidOpenTextDocumentParams;

-use ruff_db::files::system_path_to_file;
+use red_knot_workspace::watch::ChangeEvent;
+use ruff_db::Db;

 use crate::server::api::traits::{NotificationHandler, SyncNotificationHandler};
 use crate::server::client::{Notifier, Requester};
 use crate::server::Result;
 use crate::session::Session;
-use crate::system::url_to_system_path;
+use crate::system::{url_to_any_system_path, AnySystemPath};
 use crate::TextDocument;

 pub(crate) struct DidOpenTextDocumentHandler;
@@ -23,17 +24,25 @@ impl SyncNotificationHandler for DidOpenTextDocumentHandler {
        _requester: &mut Requester,
        params: DidOpenTextDocumentParams,
    ) -> Result<()> {
-        let Ok(path) = url_to_system_path(&params.text_document.uri) else {
+        let Ok(path) = url_to_any_system_path(&params.text_document.uri) else {
            return Ok(());
        };

        let document = TextDocument::new(params.text_document.text, params.text_document.version);
        session.open_text_document(params.text_document.uri, document);

-        if let Some(db) = session.workspace_db_for_path_mut(path.as_std_path()) {
-            // TODO(dhruvmanila): Store the `file` in `DocumentController`
-            let file = system_path_to_file(db, &path).unwrap();
-            file.sync(db);
+        match path {
+            AnySystemPath::System(path) => {
+                let db = match session.workspace_db_for_path_mut(path.as_std_path()) {
+                    Some(db) => db,
+                    None => session.default_workspace_db_mut(),
+                };
+                db.apply_changes(vec![ChangeEvent::Opened(path)], None);
+            }
+            AnySystemPath::SystemVirtual(virtual_path) => {
+                let db = session.default_workspace_db_mut();
+                db.files().virtual_file(db, &virtual_path);
+            }
        }

        // TODO(dhruvmanila): Publish diagnostics if the client doesn't support pull diagnostics
--- a/crates/red_knot_server/src/server/api/notifications/did_open_notebook.rs
+++ b/crates/red_knot_server/src/server/api/notifications/did_open_notebook.rs
@@ -2,7 +2,8 @@ use lsp_server::ErrorCode;
 use lsp_types::notification::DidOpenNotebookDocument;
 use lsp_types::DidOpenNotebookDocumentParams;

-use ruff_db::files::system_path_to_file;
+use red_knot_workspace::watch::ChangeEvent;
+use ruff_db::Db;

 use crate::edit::NotebookDocument;
 use crate::server::api::traits::{NotificationHandler, SyncNotificationHandler};
@@ -10,7 +11,7 @@ use crate::server::api::LSPResult;
 use crate::server::client::{Notifier, Requester};
 use crate::server::Result;
 use crate::session::Session;
-use crate::system::url_to_system_path;
+use crate::system::{url_to_any_system_path, AnySystemPath};

 pub(crate) struct DidOpenNotebookHandler;

@@ -25,7 +26,7 @@ impl SyncNotificationHandler for DidOpenNotebookHandler {
        _requester: &mut Requester,
        params: DidOpenNotebookDocumentParams,
    ) -> Result<()> {
-        let Ok(path) = url_to_system_path(&params.notebook_document.uri) else {
+        let Ok(path) = url_to_any_system_path(&params.notebook_document.uri) else {
            return Ok(());
        };

@@ -38,10 +39,18 @@ impl SyncNotificationHandler for DidOpenNotebookHandler {
        .with_failure_code(ErrorCode::InternalError)?;
        session.open_notebook_document(params.notebook_document.uri.clone(), notebook);

-        if let Some(db) = session.workspace_db_for_path_mut(path.as_std_path()) {
-            // TODO(dhruvmanila): Store the `file` in `DocumentController`
-            let file = system_path_to_file(db, &path).unwrap();
-            file.sync(db);
+        match path {
+            AnySystemPath::System(path) => {
+                let db = match session.workspace_db_for_path_mut(path.as_std_path()) {
+                    Some(db) => db,
+                    None => session.default_workspace_db_mut(),
+                };
+                db.apply_changes(vec![ChangeEvent::Opened(path)], None);
+            }
+            AnySystemPath::SystemVirtual(virtual_path) => {
+                let db = session.default_workspace_db_mut();
+                db.files().virtual_file(db, &virtual_path);
+            }
        }

        // TODO(dhruvmanila): Publish diagnostics if the client doesn't support pull diagnostics
--- a/crates/red_knot_server/src/server/api/requests/diagnostic.rs
+++ b/crates/red_knot_server/src/server/api/requests/diagnostic.rs
@@ -26,13 +26,11 @@ impl BackgroundDocumentRequestHandler for DocumentDiagnosticRequestHandler {

    fn run_with_snapshot(
        snapshot: DocumentSnapshot,
-        db: Option<RootDatabase>,
+        db: RootDatabase,
        _notifier: Notifier,
        _params: DocumentDiagnosticParams,
    ) -> Result<DocumentDiagnosticReportResult> {
-        let diagnostics = db
-            .map(|db| compute_diagnostics(&snapshot, &db))
-            .unwrap_or_default();
+        let diagnostics = compute_diagnostics(&snapshot, &db);

        Ok(DocumentDiagnosticReportResult::Report(
            DocumentDiagnosticReport::Full(RelatedFullDocumentDiagnosticReport {
@@ -48,10 +46,19 @@ impl BackgroundDocumentRequestHandler for DocumentDiagnosticRequestHandler {

 fn compute_diagnostics(snapshot: &DocumentSnapshot, db: &RootDatabase) -> Vec<Diagnostic> {
    let Some(file) = snapshot.file(db) else {
+        tracing::info!(
+            "No file found for snapshot for '{}'",
+            snapshot.query().file_url()
+        );
        return vec![];
    };
-    let Ok(diagnostics) = db.check_file(file) else {
-        return vec![];
+
+    let diagnostics = match db.check_file(file) {
+        Ok(diagnostics) => diagnostics,
+        Err(cancelled) => {
+            tracing::info!("Diagnostics computation {cancelled}");
+            return vec![];
+        }
    };

    diagnostics
@@ -65,12 +72,12 @@ fn to_lsp_diagnostic(message: &str) -> Diagnostic {
    let words = message.split(':').collect::<Vec<_>>();

    let (range, message) = match words.as_slice() {
-        [_filename, line, column, message] => {
-            let line = line.parse::<u32>().unwrap_or_default();
+        [_, _, line, column, message] | [_, line, column, message] => {
+            let line = line.parse::<u32>().unwrap_or_default().saturating_sub(1);
            let column = column.parse::<u32>().unwrap_or_default();
            (
                Range::new(
-                    Position::new(line.saturating_sub(1), column.saturating_sub(1)),
+                    Position::new(line, column.saturating_sub(1)),
                    Position::new(line, column),
                ),
                message.trim(),
--- a/crates/red_knot_server/src/server/api/traits.rs
+++ b/crates/red_knot_server/src/server/api/traits.rs
@@ -34,7 +34,7 @@ pub(super) trait BackgroundDocumentRequestHandler: RequestHandler {

    fn run_with_snapshot(
        snapshot: DocumentSnapshot,
-        db: Option<RootDatabase>,
+        db: RootDatabase,
        notifier: Notifier,
        params: <<Self as RequestHandler>::RequestType as Request>::Params,
    ) -> super::Result<<<Self as RequestHandler>::RequestType as Request>::Result>;
--- a/crates/red_knot_server/src/session.rs
+++ b/crates/red_knot_server/src/session.rs
@@ -6,15 +6,16 @@ use std::path::{Path, PathBuf};
 use std::sync::Arc;

 use anyhow::anyhow;
-use lsp_types::{ClientCapabilities, Url};
+use lsp_types::{ClientCapabilities, TextDocumentContentChangeEvent, Url};

 use red_knot_workspace::db::RootDatabase;
 use red_knot_workspace::workspace::WorkspaceMetadata;
 use ruff_db::files::{system_path_to_file, File};
 use ruff_db::system::SystemPath;
+use ruff_db::Db;

-use crate::edit::{DocumentKey, NotebookDocument};
-use crate::system::{url_to_system_path, LSPSystem};
+use crate::edit::{DocumentKey, DocumentVersion, NotebookDocument};
+use crate::system::{url_to_any_system_path, AnySystemPath, LSPSystem};
 use crate::{PositionEncoding, TextDocument};

 pub(crate) use self::capabilities::ResolvedClientCapabilities;
@@ -82,6 +83,12 @@ impl Session {
        })
    }

+    // TODO(dhruvmanila): Ideally, we should have a single method for `workspace_db_for_path_mut`
+    // and `default_workspace_db_mut` but the borrow checker doesn't allow that.
+    // https://github.com/astral-sh/ruff/pull/13041#discussion_r1726725437
+
+    /// Returns a reference to the workspace [`RootDatabase`] corresponding to the given path, if
+    /// any.
    pub(crate) fn workspace_db_for_path(&self, path: impl AsRef<Path>) -> Option<&RootDatabase> {
        self.workspaces
            .range(..=path.as_ref().to_path_buf())
@@ -89,6 +96,8 @@ impl Session {
            .map(|(_, db)| db)
    }

+    /// Returns a mutable reference to the workspace [`RootDatabase`] corresponding to the given
+    /// path, if any.
    pub(crate) fn workspace_db_for_path_mut(
        &mut self,
        path: impl AsRef<Path>,
@@ -99,6 +108,19 @@ impl Session {
            .map(|(_, db)| db)
    }

+    /// Returns a reference to the default workspace [`RootDatabase`]. The default workspace is the
+    /// minimum root path in the workspace map.
+    pub(crate) fn default_workspace_db(&self) -> &RootDatabase {
+        // SAFETY: Currently, red knot only support a single workspace.
+        self.workspaces.values().next().unwrap()
+    }
+
+    /// Returns a mutable reference to the default workspace [`RootDatabase`].
+    pub(crate) fn default_workspace_db_mut(&mut self) -> &mut RootDatabase {
+        // SAFETY: Currently, red knot only support a single workspace.
+        self.workspaces.values_mut().next().unwrap()
+    }
+
    pub fn key_from_url(&self, url: Url) -> DocumentKey {
        self.index().key_from_url(url)
    }
@@ -125,6 +147,20 @@ impl Session {
        self.index_mut().open_text_document(url, document);
    }

+    /// Updates a text document at the associated `key`.
+    ///
+    /// The document key must point to a text document, or this will throw an error.
+    pub(crate) fn update_text_document(
+        &mut self,
+        key: &DocumentKey,
+        content_changes: Vec<TextDocumentContentChangeEvent>,
+        new_version: DocumentVersion,
+    ) -> crate::Result<()> {
+        let position_encoding = self.position_encoding;
+        self.index_mut()
+            .update_text_document(key, content_changes, new_version, position_encoding)
+    }
+
    /// De-registers a document, specified by its key.
    /// Calling this multiple times for the same document is a logic error.
    pub(crate) fn close_document(&mut self, key: &DocumentKey) -> crate::Result<()> {
@@ -211,6 +247,7 @@ impl Drop for MutIndexGuard<'_> {

 /// An immutable snapshot of `Session` that references
 /// a specific document.
+#[derive(Debug)]
 pub struct DocumentSnapshot {
    resolved_client_capabilities: Arc<ResolvedClientCapabilities>,
    document_ref: index::DocumentQuery,
@@ -231,7 +268,12 @@ impl DocumentSnapshot {
    }

    pub(crate) fn file(&self, db: &RootDatabase) -> Option<File> {
-        let path = url_to_system_path(self.document_ref.file_url()).ok()?;
-        system_path_to_file(db, path).ok()
+        match url_to_any_system_path(self.document_ref.file_url()).ok()? {
+            AnySystemPath::System(path) => system_path_to_file(db, path).ok(),
+            AnySystemPath::SystemVirtual(virtual_path) => db
+                .files()
+                .try_virtual_file(&virtual_path)
+                .map(|virtual_file| virtual_file.file()),
+        }
    }
 }
--- a/crates/red_knot_server/src/system.rs
+++ b/crates/red_knot_server/src/system.rs
@@ -8,27 +8,40 @@ use ruff_db::file_revision::FileRevision;
 use ruff_db::system::walk_directory::WalkDirectoryBuilder;
 use ruff_db::system::{
    DirectoryEntry, FileType, Metadata, OsSystem, Result, System, SystemPath, SystemPathBuf,
-    SystemVirtualPath,
+    SystemVirtualPath, SystemVirtualPathBuf,
 };
 use ruff_notebook::{Notebook, NotebookError};

 use crate::session::index::Index;
 use crate::DocumentQuery;

-/// Converts the given [`Url`] to a [`SystemPathBuf`].
+/// Converts the given [`Url`] to an [`AnySystemPath`].
+///
+/// If the URL scheme is `file`, then the path is converted to a [`SystemPathBuf`]. Otherwise, the
+/// URL is converted to a [`SystemVirtualPathBuf`].
 ///
 /// This fails in the following cases:
-/// * The URL scheme is not `file`.
 /// * The URL cannot be converted to a file path (refer to [`Url::to_file_path`]).
 /// * If the URL is not a valid UTF-8 string.
-pub(crate) fn url_to_system_path(url: &Url) -> std::result::Result<SystemPathBuf, ()> {
+pub(crate) fn url_to_any_system_path(url: &Url) -> std::result::Result<AnySystemPath, ()> {
    if url.scheme() == "file" {
-        Ok(SystemPathBuf::from_path_buf(url.to_file_path()?).map_err(|_| ())?)
+        Ok(AnySystemPath::System(
+            SystemPathBuf::from_path_buf(url.to_file_path()?).map_err(|_| ())?,
+        ))
    } else {
-        Err(())
+        Ok(AnySystemPath::SystemVirtual(
+            SystemVirtualPath::new(url.as_str()).to_path_buf(),
+        ))
    }
 }

+/// Represents either a [`SystemPath`] or a [`SystemVirtualPath`].
+#[derive(Debug)]
+pub(crate) enum AnySystemPath {
+    System(SystemPathBuf),
+    SystemVirtual(SystemVirtualPathBuf),
+}
+
 #[derive(Debug)]
 pub(crate) struct LSPSystem {
    /// A read-only copy of the index where the server stores all the open documents and settings.
@@ -144,19 +157,6 @@ impl System for LSPSystem {
        }
    }

-    fn virtual_path_metadata(&self, path: &SystemVirtualPath) -> Result<Metadata> {
-        // Virtual paths only exists in the LSP system, so we don't need to check the OS system.
-        let document = self
-            .system_virtual_path_to_document_ref(path)?
-            .ok_or_else(|| virtual_path_not_found(path))?;
-
-        Ok(Metadata::new(
-            document_revision(&document),
-            None,
-            FileType::File,
-        ))
-    }
-
    fn read_virtual_path_to_string(&self, path: &SystemVirtualPath) -> Result<String> {
        let document = self
            .system_virtual_path_to_document_ref(path)?
--- a/crates/red_knot_wasm/src/lib.rs
+++ b/crates/red_knot_wasm/src/lib.rs
@@ -234,13 +234,6 @@ impl System for WasmSystem {
        Notebook::from_source_code(&content)
    }

-    fn virtual_path_metadata(
-        &self,
-        _path: &SystemVirtualPath,
-    ) -> ruff_db::system::Result<Metadata> {
-        Err(not_found())
-    }
-
    fn read_virtual_path_to_string(
        &self,
        _path: &SystemVirtualPath,
--- a/crates/red_knot_wasm/tests/api.rs
+++ b/crates/red_knot_wasm/tests/api.rs
@@ -11,14 +11,14 @@ fn check() {
    };
    let mut workspace = Workspace::new("/", &settings).expect("Workspace to be created");

-    let test = workspace
+    workspace
        .open_file("test.py", "import random22\n")
        .expect("File to be opened");

-    let result = workspace.check_file(&test).expect("Check to succeed");
+    let result = workspace.check().expect("Check to succeed");

    assert_eq!(
        result,
-        vec!["/test.py:1:8: Import 'random22' could not be resolved.",]
+        vec!["/test.py:1:8: Cannot resolve import 'random22'."]
    );
 }
--- a/crates/red_knot_workspace/Cargo.toml
+++ b/crates/red_knot_workspace/Cargo.toml
@@ -22,12 +22,14 @@ ruff_text_size = { workspace = true }
 anyhow = { workspace = true }
 crossbeam = { workspace = true }
 notify = { workspace = true }
+rayon = { workspace = true }
 rustc-hash = { workspace = true }
 salsa = { workspace = true }
 tracing = { workspace = true }

 [dev-dependencies]
-ruff_db = { workspace = true, features = ["testing"]}
+ruff_db = { workspace = true, features = ["testing"] }
+tempfile = { workspace = true }

 [lints]
 workspace = true
--- a/crates/red_knot_workspace/resources/test/corpus/04_assign_named_expr.py
+++ b/crates/red_knot_workspace/resources/test/corpus/04_assign_named_expr.py
@@ -0,0 +1,2 @@
+x = 0
+(x := x + 1)
--- a/crates/red_knot_workspace/resources/test/corpus/10_if_with_named_expr.py
+++ b/crates/red_knot_workspace/resources/test/corpus/10_if_with_named_expr.py
@@ -0,0 +1,3 @@
+x = 0
+if x := x + 1:
+    pass
--- a/crates/red_knot_workspace/resources/test/corpus/25_func_annotations_same_name.py
+++ b/crates/red_knot_workspace/resources/test/corpus/25_func_annotations_same_name.py
@@ -0,0 +1,11 @@
+def bool(x) -> bool:
+    return True
+
+
+class MyClass: ...
+
+
+def MyClass() -> MyClass: ...
+
+
+def x(self) -> x: ...
--- a/crates/red_knot_workspace/resources/test/corpus/26_func_defaults_same_name.py
+++ b/crates/red_knot_workspace/resources/test/corpus/26_func_defaults_same_name.py
@@ -0,0 +1,2 @@
+def bool(x=bool):
+    return x
--- a/crates/red_knot_workspace/resources/test/corpus/85_match_guard_with_named_expr.py
+++ b/crates/red_knot_workspace/resources/test/corpus/85_match_guard_with_named_expr.py
@@ -0,0 +1,3 @@
+match x:
+    case [1, 0] if x := x[:0]:
+        y = 1
--- a/crates/red_knot_workspace/src/db.rs
+++ b/crates/red_knot_workspace/src/db.rs
@@ -56,6 +56,8 @@ impl RootDatabase {
    }

    pub fn check_file(&self, file: File) -> Result<Vec<String>, Cancelled> {
+        let _span = tracing::debug_span!("check_file", file=%file.path(self)).entered();
+
        self.with_db(|db| check_file(db, file))
    }

--- a/crates/red_knot_workspace/src/db/changes.rs
+++ b/crates/red_knot_workspace/src/db/changes.rs
@@ -50,7 +50,7 @@ impl RootDatabase {
        };

        for change in changes {
-            if let Some(path) = change.path() {
+            if let Some(path) = change.system_path() {
                if matches!(
                    path.file_name(),
                    Some(".gitignore" | ".ignore" | "ruff.toml" | ".ruff.toml" | "pyproject.toml")
@@ -72,7 +72,8 @@ impl RootDatabase {
            }

            match change {
-                watch::ChangeEvent::Changed { path, kind: _ } => sync_path(self, &path),
+                watch::ChangeEvent::Changed { path, kind: _ }
+                | watch::ChangeEvent::Opened(path) => sync_path(self, &path),

                watch::ChangeEvent::Created { kind, path } => {
                    match kind {
@@ -130,6 +131,17 @@ impl RootDatabase {
                    }
                }

+                watch::ChangeEvent::CreatedVirtual(path)
+                | watch::ChangeEvent::ChangedVirtual(path) => {
+                    File::sync_virtual_path(self, &path);
+                }
+
+                watch::ChangeEvent::DeletedVirtual(path) => {
+                    if let Some(virtual_file) = self.files().try_virtual_file(&path) {
+                        virtual_file.close(self);
+                    }
+                }
+
                watch::ChangeEvent::Rescan => {
                    workspace_change = true;
                    Files::sync_all(self);
--- a/crates/red_knot_workspace/src/lint.rs
+++ b/crates/red_knot_workspace/src/lint.rs
@@ -7,7 +7,7 @@ use red_knot_python_semantic::types::Type;
 use red_knot_python_semantic::{HasTy, ModuleName, SemanticModel};
 use ruff_db::files::File;
 use ruff_db::parsed::{parsed_module, ParsedModule};
-use ruff_db::source::{line_index, source_text, SourceText};
+use ruff_db::source::{source_text, SourceText};
 use ruff_python_ast as ast;
 use ruff_python_ast::visitor::{walk_expr, walk_stmt, Visitor};
 use ruff_text_size::{Ranged, TextSize};
@@ -48,19 +48,6 @@ pub(crate) fn lint_syntax(db: &dyn Db, file_id: File) -> Vec<String> {
        };
        visitor.visit_body(&ast.body);
        diagnostics = visitor.diagnostics;
-    } else {
-        let path = file_id.path(db);
-        let line_index = line_index(db.upcast(), file_id);
-        diagnostics.extend(parsed.errors().iter().map(|err| {
-            let source_location = line_index.source_location(err.location.start(), source.as_str());
-            format!(
-                "{}:{}:{}: {}",
-                path.as_str(),
-                source_location.row,
-                source_location.column,
-                err,
-            )
-        }));
    }

    diagnostics
@@ -177,7 +164,7 @@ fn lint_bad_override(context: &SemanticLintContext, class: &ast::StmtClassDef) {
        if ty.has_decorator(db, override_ty) {
            let method_name = ty.name(db);
            if class_ty
-                .inherited_class_member(db, &method_name)
+                .inherited_class_member(db, method_name)
                .is_unbound()
            {
                // TODO should have a qualname() method to support nested classes
--- a/crates/red_knot_workspace/src/watch.rs
+++ b/crates/red_knot_workspace/src/watch.rs
@@ -1,4 +1,4 @@
-use ruff_db::system::{SystemPath, SystemPathBuf};
+use ruff_db::system::{SystemPath, SystemPathBuf, SystemVirtualPathBuf};
 pub use watcher::{directory_watcher, EventHandler, Watcher};
 pub use workspace_watcher::WorkspaceWatcher;

@@ -20,6 +20,9 @@ mod workspace_watcher;
 /// event instead of emitting an event for each file or subdirectory in that path.
 #[derive(Debug, PartialEq, Eq)]
 pub enum ChangeEvent {
+    /// The file corresponding to the given path was opened in an editor.
+    Opened(SystemPathBuf),
+
    /// A new path was created
    Created {
        path: SystemPathBuf,
@@ -38,6 +41,15 @@ pub enum ChangeEvent {
        kind: DeletedKind,
    },

+    /// A new virtual path was created.
+    CreatedVirtual(SystemVirtualPathBuf),
+
+    /// The content of a virtual path was changed.
+    ChangedVirtual(SystemVirtualPathBuf),
+
+    /// A virtual path was deleted.
+    DeletedVirtual(SystemVirtualPathBuf),
+
    /// The file watcher failed to observe some changes and now is out of sync with the file system.
    ///
    /// This can happen if many files are changed at once. The consumer should rescan all files to catch up
@@ -46,16 +58,27 @@ pub enum ChangeEvent {
 }

 impl ChangeEvent {
-    pub fn file_name(&self) -> Option<&str> {
-        self.path().and_then(|path| path.file_name())
+    /// Creates a new [`Changed`] event for the file content at the given path.
+    ///
+    /// [`Changed`]: ChangeEvent::Changed
+    pub fn file_content_changed(path: SystemPathBuf) -> ChangeEvent {
+        ChangeEvent::Changed {
+            path,
+            kind: ChangedKind::FileContent,
+        }
    }

-    pub fn path(&self) -> Option<&SystemPath> {
+    pub fn file_name(&self) -> Option<&str> {
+        self.system_path().and_then(|path| path.file_name())
+    }
+
+    pub fn system_path(&self) -> Option<&SystemPath> {
        match self {
-            ChangeEvent::Created { path, .. }
+            ChangeEvent::Opened(path)
+            | ChangeEvent::Created { path, .. }
            | ChangeEvent::Changed { path, .. }
            | ChangeEvent::Deleted { path, .. } => Some(path),
-            ChangeEvent::Rescan => None,
+            _ => None,
        }
    }
 }
--- a/crates/red_knot_workspace/src/workspace.rs
+++ b/crates/red_knot_workspace/src/workspace.rs
@@ -6,6 +6,7 @@ use salsa::{Durability, Setter as _};
 pub use metadata::{PackageMetadata, WorkspaceMetadata};
 use red_knot_python_semantic::types::check_types;
 use red_knot_python_semantic::SearchPathSettings;
+use ruff_db::parsed::parsed_module;
 use ruff_db::source::{line_index, source_text, SourceDiagnostic};
 use ruff_db::{
    files::{system_path_to_file, File},
@@ -14,7 +15,8 @@ use ruff_db::{
 use ruff_python_ast::{name::Name, PySourceType};
 use ruff_text_size::Ranged;

-use crate::workspace::files::{Index, Indexed, PackageFiles};
+use crate::db::RootDatabase;
+use crate::workspace::files::{Index, Indexed, IndexedIter, PackageFiles};
 use crate::{
    db::Db,
    lint::{lint_semantic, lint_syntax},
@@ -189,23 +191,35 @@ impl Workspace {
    }

    /// Checks all open files in the workspace and its dependencies.
-    #[tracing::instrument(level = "debug", skip_all)]
-    pub fn check(self, db: &dyn Db) -> Vec<String> {
+    pub fn check(self, db: &RootDatabase) -> Vec<String> {
+        let workspace_span = tracing::debug_span!("check_workspace");
+        let _span = workspace_span.enter();
+
        tracing::debug!("Checking workspace");
+        let files = WorkspaceFiles::new(db, self);
+        let result = Arc::new(std::sync::Mutex::new(Vec::new()));
+        let inner_result = Arc::clone(&result);

-        let mut result = Vec::new();
+        let db = db.snapshot();
+        let workspace_span = workspace_span.clone();

-        if let Some(open_files) = self.open_files(db) {
-            for file in open_files {
-                result.extend_from_slice(&check_file(db, *file));
+        rayon::scope(move |scope| {
+            for file in &files {
+                let result = inner_result.clone();
+                let db = db.snapshot();
+                let workspace_span = workspace_span.clone();
+
+                scope.spawn(move |_| {
+                    let check_file_span = tracing::debug_span!(parent: &workspace_span, "check_file", file=%file.path(&db));
+                    let _entered = check_file_span.entered();
+
+                    let file_diagnostics = check_file(&db, file);
+                    result.lock().unwrap().extend(file_diagnostics);
+                });
            }
-        } else {
-            for package in self.packages(db) {
-                result.extend(package.check(db));
-            }
-        }
+        });

-        result
+        Arc::into_inner(result).unwrap().into_inner().unwrap()
    }

    /// Opens a file in the workspace.
@@ -283,7 +297,6 @@ impl Workspace {
    }
 }

-#[salsa::tracked]
 impl Package {
    pub fn root(self, db: &dyn Db) -> &SystemPath {
        self.root_buf(db)
@@ -323,19 +336,6 @@ impl Package {
        index.insert(file);
    }

-    #[tracing::instrument(level = "debug", skip(db))]
-    pub(crate) fn check(self, db: &dyn Db) -> Vec<String> {
-        tracing::debug!("Checking package '{}'", self.root(db));
-
-        let mut result = Vec::new();
-        for file in &self.files(db) {
-            let diagnostics = check_file(db, file);
-            result.extend_from_slice(&diagnostics);
-        }
-
-        result
-    }
-
    /// Returns the files belonging to this package.
    pub fn files(self, db: &dyn Db) -> Indexed<'_> {
        let files = self.file_set(db);
@@ -383,9 +383,7 @@ impl Package {

 #[salsa::tracked]
 pub(super) fn check_file(db: &dyn Db, file: File) -> Vec<String> {
-    let path = file.path(db);
-    let _span = tracing::debug_span!("check_file", file=%path).entered();
-    tracing::debug!("Checking file '{path}'");
+    tracing::debug!("Checking file '{path}'", path = file.path(db));

    let mut diagnostics = Vec::new();

@@ -404,6 +402,17 @@ pub(super) fn check_file(db: &dyn Db, file: File) -> Vec<String> {
        return diagnostics;
    }

+    let parsed = parsed_module(db.upcast(), file);
+
+    if !parsed.errors().is_empty() {
+        let path = file.path(db);
+        let line_index = line_index(db.upcast(), file);
+        diagnostics.extend(parsed.errors().iter().map(|err| {
+            let source_location = line_index.source_location(err.location.start(), source.as_str());
+            format!("{path}:{source_location}: {message}", message = err.error)
+        }));
+    }
+
    for diagnostic in check_types(db.upcast(), file) {
        let index = line_index(db.upcast(), diagnostic.file());
        let location = index.source_location(diagnostic.start(), source.as_str());
@@ -462,6 +471,73 @@ fn discover_package_files(db: &dyn Db, path: &SystemPath) -> FxHashSet<File> {
    files
 }

+#[derive(Debug)]
+enum WorkspaceFiles<'a> {
+    OpenFiles(&'a FxHashSet<File>),
+    PackageFiles(Vec<Indexed<'a>>),
+}
+
+impl<'a> WorkspaceFiles<'a> {
+    fn new(db: &'a dyn Db, workspace: Workspace) -> Self {
+        if let Some(open_files) = workspace.open_files(db) {
+            WorkspaceFiles::OpenFiles(open_files)
+        } else {
+            WorkspaceFiles::PackageFiles(
+                workspace
+                    .packages(db)
+                    .map(|package| package.files(db))
+                    .collect(),
+            )
+        }
+    }
+}
+
+impl<'a> IntoIterator for &'a WorkspaceFiles<'a> {
+    type Item = File;
+    type IntoIter = WorkspaceFilesIter<'a>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        match self {
+            WorkspaceFiles::OpenFiles(files) => WorkspaceFilesIter::OpenFiles(files.iter()),
+            WorkspaceFiles::PackageFiles(package_files) => {
+                let mut package_files = package_files.iter();
+                WorkspaceFilesIter::PackageFiles {
+                    current: package_files.next().map(IntoIterator::into_iter),
+                    package_files,
+                }
+            }
+        }
+    }
+}
+
+enum WorkspaceFilesIter<'db> {
+    OpenFiles(std::collections::hash_set::Iter<'db, File>),
+    PackageFiles {
+        package_files: std::slice::Iter<'db, Indexed<'db>>,
+        current: Option<IndexedIter<'db>>,
+    },
+}
+
+impl Iterator for WorkspaceFilesIter<'_> {
+    type Item = File;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self {
+            WorkspaceFilesIter::OpenFiles(files) => files.next().copied(),
+            WorkspaceFilesIter::PackageFiles {
+                package_files,
+                current,
+            } => loop {
+                if let Some(file) = current.as_mut().and_then(Iterator::next) {
+                    return Some(file);
+                }
+
+                *current = Some(package_files.next()?.into_iter());
+            },
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
    use ruff_db::files::system_path_to_file;
--- a/crates/red_knot_workspace/src/workspace/files.rs
+++ b/crates/red_knot_workspace/src/workspace/files.rs
@@ -158,9 +158,11 @@ impl Deref for Indexed<'_> {
    }
 }

+pub(super) type IndexedIter<'a> = std::iter::Copied<std::collections::hash_set::Iter<'a, File>>;
+
 impl<'a> IntoIterator for &'a Indexed<'_> {
    type Item = File;
-    type IntoIter = std::iter::Copied<std::collections::hash_set::Iter<'a, File>>;
+    type IntoIter = IndexedIter<'a>;

    fn into_iter(self) -> Self::IntoIter {
        self.files.iter().copied()
--- a/crates/red_knot_workspace/tests/check.rs
+++ b/crates/red_knot_workspace/tests/check.rs
@@ -21,19 +21,27 @@ fn setup_db(workspace_root: &SystemPath) -> anyhow::Result<RootDatabase> {
 #[test]
 #[allow(clippy::print_stdout)]
 fn corpus_no_panic() -> anyhow::Result<()> {
-    let corpus = PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("resources/test/corpus");
-    let system_corpus =
-        SystemPathBuf::from_path_buf(corpus.clone()).expect("corpus path to be UTF8");
-    let db = setup_db(&system_corpus)?;
+    let root = SystemPathBuf::from_path_buf(tempfile::TempDir::new()?.into_path()).unwrap();
+    let db = setup_db(&root)?;

-    for path in fs::read_dir(&corpus).expect("corpus to be a directory") {
-        let path = path.expect("path to not be an error").path();
-        println!("checking {path:?}");
-        let path = SystemPathBuf::from_path_buf(path.clone()).expect("path to be UTF-8");
+    let corpus = PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("resources/test/corpus");
+
+    for path in fs::read_dir(&corpus)? {
+        let source = path?.path();
+        println!("checking {source:?}");
+        let source_fn = source.file_name().unwrap().to_str().unwrap();
+        let py_dest = root.join(source_fn);
+        fs::copy(&source, py_dest.as_std_path())?;
        // this test is only asserting that we can pull every expression type without a panic
        // (and some non-expressions that clearly define a single type)
-        let file = system_path_to_file(&db, path).expect("file to exist");
+        let file = system_path_to_file(&db, py_dest).unwrap();
+        pull_types(&db, file);

+        // try the file as a stub also
+        println!("re-checking as .pyi");
+        let pyi_dest = root.join(format!("{source_fn}i"));
+        std::fs::copy(source, pyi_dest.as_std_path())?;
+        let file = system_path_to_file(&db, pyi_dest).unwrap();
        pull_types(&db, file);
    }
    Ok(())
--- a/crates/ruff/Cargo.toml
+++ b/crates/ruff/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "ruff"
-version = "0.6.1"
+version = "0.6.4"
 publish = true
 authors = { workspace = true }
 edition = { workspace = true }
--- a/crates/ruff/src/commands/format.rs
+++ b/crates/ruff/src/commands/format.rs
@@ -810,7 +810,11 @@ pub(super) fn warn_incompatible_formatter_settings(resolver: &Resolver) {
            .map(|rule| format!("`{}`", rule.noqa_code()))
            .collect();
        rule_names.sort();
-        warn_user_once!("The following rules may cause conflicts when used with the formatter: {}. To avoid unexpected behavior, we recommend disabling these rules, either by removing them from the `select` or `extend-select` configuration, or adding them to the `ignore` configuration.", rule_names.join(", "));
+        if let [rule] = rule_names.as_slice() {
+            warn_user_once!("The following rule may cause conflicts when used with the formatter: {rule}. To avoid unexpected behavior, we recommend disabling this rule, either by removing it from the `select` or `extend-select` configuration, or adding it to the `ignore` configuration.");
+        } else {
+            warn_user_once!("The following rules may cause conflicts when used with the formatter: {}. To avoid unexpected behavior, we recommend disabling these rules, either by removing them from the `select` or `extend-select` configuration, or adding them to the `ignore` configuration.", rule_names.join(", "));
+        }
    }

    // Next, validate settings-specific incompatibilities.
--- a/crates/ruff/src/printer.rs
+++ b/crates/ruff/src/printer.rs
@@ -151,15 +151,15 @@ impl Printer {
                    let fix_prefix = format!("[{}]", "*".cyan());

                    if self.unsafe_fixes.is_hint() {
-                        if fixables.applicable > 0 && fixables.unapplicable_unsafe > 0 {
-                            let es = if fixables.unapplicable_unsafe == 1 {
+                        if fixables.applicable > 0 && fixables.inapplicable_unsafe > 0 {
+                            let es = if fixables.inapplicable_unsafe == 1 {
                                ""
                            } else {
                                "es"
                            };
                            writeln!(writer,
                                "{fix_prefix} {} fixable with the `--fix` option ({} hidden fix{es} can be enabled with the `--unsafe-fixes` option).",
-                                fixables.applicable, fixables.unapplicable_unsafe
+                                fixables.applicable, fixables.inapplicable_unsafe
                            )?;
                        } else if fixables.applicable > 0 {
                            // Only applicable fixes
@@ -169,15 +169,15 @@ impl Printer {
                                fixables.applicable,
                            )?;
                        } else {
-                            // Only unapplicable fixes
-                            let es = if fixables.unapplicable_unsafe == 1 {
+                            // Only inapplicable fixes
+                            let es = if fixables.inapplicable_unsafe == 1 {
                                ""
                            } else {
                                "es"
                            };
                            writeln!(writer,
                                "No fixes available ({} hidden fix{es} can be enabled with the `--unsafe-fixes` option).",
-                                fixables.unapplicable_unsafe
+                                fixables.inapplicable_unsafe
                            )?;
                        }
                    } else {
@@ -194,7 +194,7 @@ impl Printer {
                // Check if there are unapplied fixes
                let unapplied = {
                    if let Some(fixables) = fixables {
-                        fixables.unapplicable_unsafe
+                        fixables.inapplicable_unsafe
                    } else {
                        0
                    }
@@ -545,33 +545,33 @@ fn print_fix_summary(writer: &mut dyn Write, fixed: &FixMap) -> Result<()> {
 #[derive(Debug)]
 struct FixableStatistics {
    applicable: u32,
-    unapplicable_unsafe: u32,
+    inapplicable_unsafe: u32,
 }

 impl FixableStatistics {
    fn try_from(diagnostics: &Diagnostics, unsafe_fixes: UnsafeFixes) -> Option<Self> {
        let mut applicable = 0;
-        let mut unapplicable_unsafe = 0;
+        let mut inapplicable_unsafe = 0;

        for message in &diagnostics.messages {
            if let Some(fix) = message.fix() {
                if fix.applies(unsafe_fixes.required_applicability()) {
                    applicable += 1;
                } else {
-                    // Do not include unapplicable fixes at other levels that do not provide an opt-in
+                    // Do not include inapplicable fixes at other levels that do not provide an opt-in
                    if fix.applicability().is_unsafe() {
-                        unapplicable_unsafe += 1;
+                        inapplicable_unsafe += 1;
                    }
                }
            }
        }

-        if applicable == 0 && unapplicable_unsafe == 0 {
+        if applicable == 0 && inapplicable_unsafe == 0 {
            None
        } else {
            Some(Self {
                applicable,
-                unapplicable_unsafe,
+                inapplicable_unsafe,
            })
        }
    }
--- a/crates/ruff/tests/format.rs
+++ b/crates/ruff/tests/format.rs
@@ -785,7 +785,7 @@ if condition:
    	print('Should change quotes')

    ----- stderr -----
-    warning: The following rules may cause conflicts when used with the formatter: `COM812`. To avoid unexpected behavior, we recommend disabling these rules, either by removing them from the `select` or `extend-select` configuration, or adding them to the `ignore` configuration.
+    warning: The following rule may cause conflicts when used with the formatter: `COM812`. To avoid unexpected behavior, we recommend disabling this rule, either by removing it from the `select` or `extend-select` configuration, or adding it to the `ignore` configuration.
    "###);
    Ok(())
 }
--- a/crates/ruff_benchmark/Cargo.toml
+++ b/crates/ruff_benchmark/Cargo.toml
@@ -37,13 +37,14 @@ name = "red_knot"
 harness = false

 [dependencies]
+codspeed-criterion-compat = { workspace = true, default-features = false, optional = true }
+criterion = { workspace = true, default-features = false }
 once_cell = { workspace = true }
+rayon = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 url = { workspace = true }
 ureq = { workspace = true }
-criterion = { workspace = true, default-features = false }
-codspeed-criterion-compat = { workspace = true, default-features = false, optional = true }

 [dev-dependencies]
 ruff_db = { workspace = true }
--- a/crates/ruff_benchmark/benches/red_knot.rs
+++ b/crates/ruff_benchmark/benches/red_knot.rs
@@ -1,5 +1,6 @@
 #![allow(clippy::disallowed_names)]

+use rayon::ThreadPoolBuilder;
 use red_knot_python_semantic::PythonVersion;
 use red_knot_workspace::db::RootDatabase;
 use red_knot_workspace::watch::{ChangeEvent, ChangedKind};
@@ -20,18 +21,9 @@ struct Case {

 const TOMLLIB_312_URL: &str = "https://raw.githubusercontent.com/python/cpython/8e8a4baf652f6e1cee7acde9d78c4b6154539748/Lib/tomllib";

-// This first "unresolved import" is because we don't understand `*` imports yet.
-// The following "unresolved import" violations are because we can't distinguish currently from
-// "Symbol exists in the module but its type is unknown" and
-// "Symbol does not exist in the module"
+// The failed import from 'collections.abc' is due to lack of support for 'import *'.
 static EXPECTED_DIAGNOSTICS: &[&str] = &[
-    "/src/tomllib/_parser.py:7:29: Could not resolve import of 'Iterable' from 'collections.abc'",
-    "/src/tomllib/_parser.py:10:20: Could not resolve import of 'Any' from 'typing'",
-    "/src/tomllib/_parser.py:13:5: Could not resolve import of 'RE_DATETIME' from '._re'",
-    "/src/tomllib/_parser.py:14:5: Could not resolve import of 'RE_LOCALTIME' from '._re'",
-    "/src/tomllib/_parser.py:15:5: Could not resolve import of 'RE_NUMBER' from '._re'",
-    "/src/tomllib/_parser.py:20:21: Could not resolve import of 'Key' from '._types'",
-    "/src/tomllib/_parser.py:20:26: Could not resolve import of 'ParseFloat' from '._types'",
+    "/src/tomllib/_parser.py:7:29: Module 'collections.abc' has no member 'Iterable'",
    "Line 69 is too long (89 characters)",
    "Use double quotes for strings",
    "Use double quotes for strings",
@@ -40,25 +32,7 @@ static EXPECTED_DIAGNOSTICS: &[&str] = &[
    "Use double quotes for strings",
    "Use double quotes for strings",
    "Use double quotes for strings",
-    "/src/tomllib/_parser.py:153:22: Name 'key' used when not defined.",
-    "/src/tomllib/_parser.py:153:27: Name 'flag' used when not defined.",
-    "/src/tomllib/_parser.py:159:16: Name 'k' used when not defined.",
-    "/src/tomllib/_parser.py:161:25: Name 'k' used when not defined.",
-    "/src/tomllib/_parser.py:168:16: Name 'k' used when not defined.",
-    "/src/tomllib/_parser.py:169:22: Name 'k' used when not defined.",
-    "/src/tomllib/_parser.py:170:25: Name 'k' used when not defined.",
-    "/src/tomllib/_parser.py:180:16: Name 'k' used when not defined.",
-    "/src/tomllib/_parser.py:182:31: Name 'k' used when not defined.",
-    "/src/tomllib/_parser.py:206:16: Name 'k' used when not defined.",
-    "/src/tomllib/_parser.py:207:22: Name 'k' used when not defined.",
-    "/src/tomllib/_parser.py:208:25: Name 'k' used when not defined.",
-    "/src/tomllib/_parser.py:330:32: Name 'header' used when not defined.",
-    "/src/tomllib/_parser.py:330:41: Name 'key' used when not defined.",
-    "/src/tomllib/_parser.py:333:26: Name 'cont_key' used when not defined.",
-    "/src/tomllib/_parser.py:334:71: Name 'cont_key' used when not defined.",
-    "/src/tomllib/_parser.py:337:31: Name 'cont_key' used when not defined.",
    "/src/tomllib/_parser.py:628:75: Name 'e' used when not defined.",
-    "/src/tomllib/_parser.py:686:23: Name 'parse_float' used when not defined.",
 ];

 fn get_test_file(name: &str) -> TestFile {
@@ -112,7 +86,25 @@ fn setup_case() -> Case {
    }
 }

+static RAYON_INITIALIZED: std::sync::Once = std::sync::Once::new();
+
+fn setup_rayon() {
+    // Initialize the rayon thread pool outside the benchmark because it has a significant cost.
+    // We limit the thread pool to only one (the current thread) because we're focused on
+    // where red knot spends time and less about how well the code runs concurrently.
+    // We might want to add a benchmark focusing on concurrency to detect congestion in the future.
+    RAYON_INITIALIZED.call_once(|| {
+        ThreadPoolBuilder::new()
+            .num_threads(1)
+            .use_current_thread()
+            .build_global()
+            .unwrap();
+    });
+}
+
 fn benchmark_incremental(criterion: &mut Criterion) {
+    setup_rayon();
+
    criterion.bench_function("red_knot_check_file[incremental]", |b| {
        b.iter_batched_ref(
            || {
@@ -149,6 +141,8 @@ fn benchmark_incremental(criterion: &mut Criterion) {
 }

 fn benchmark_cold(criterion: &mut Criterion) {
+    setup_rayon();
+
    criterion.bench_function("red_knot_check_file[cold]", |b| {
        b.iter_batched_ref(
            setup_case,
--- a/Show More
+++ b/Show More