Bump 0.11.2 (#16896)

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

.github/CODEOWNERS

@@ -18,6 +18,7 @@
 /python/py-fuzzer/ @AlexWaygood
 
 # red-knot
-/crates/red_knot* @carljm @MichaReiser @AlexWaygood @sharkdp
-/crates/ruff_db/ @carljm @MichaReiser @AlexWaygood @sharkdp
-/scripts/knot_benchmark/ @carljm @MichaReiser @AlexWaygood @sharkdp
+/crates/red_knot* @carljm @MichaReiser @AlexWaygood @sharkdp @dcreager
+/crates/ruff_db/ @carljm @MichaReiser @AlexWaygood @sharkdp @dcreager
+/scripts/knot_benchmark/ @carljm @MichaReiser @AlexWaygood @sharkdp @dcreager
+/crates/red_knot_python_semantic @carljm @AlexWaygood @sharkdp @dcreager

.github/renovate.json5

@@ -40,6 +40,17 @@
     enabled: true,
   },
   packageRules: [
+    // Pin GitHub Actions to immutable SHAs.
+    {
+      matchDepTypes: ["action"],
+      pinDigests: true,
+    },
+    // Annotate GitHub Actions SHAs with a SemVer version.
+    {
+      extends: ["helpers:pinGitHubActionDigests"],
+      extractVersion: "^(?<version>v?\\d+\\.\\d+\\.\\d+)$",
+      versioning: "regex:^v?(?<major>\\d+)(\\.(?<minor>\\d+)\\.(?<patch>\\d+))?$",
+    },
     {
       // Group upload/download artifact updates, the versions are dependent
       groupName: "Artifact GitHub Actions dependencies",

.github/workflows/build-binaries.yml

@@ -39,17 +39,17 @@ jobs:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
       - name: "Build sdist"
-        uses: PyO3/maturin-action@v1
+        uses: PyO3/maturin-action@36db84001d74475ad1b8e6613557ae4ee2dc3598 # v1
         with:
           command: sdist
           args: --out dist
@@ -59,7 +59,7 @@ jobs:
           "${MODULE_NAME}" --help
           python -m "${MODULE_NAME}" --help
       - name: "Upload sdist"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: wheels-sdist
           path: dist
@@ -68,23 +68,23 @@ jobs:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
     runs-on: macos-14
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
           architecture: x64
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
       - name: "Build wheels - x86_64"
-        uses: PyO3/maturin-action@v1
+        uses: PyO3/maturin-action@36db84001d74475ad1b8e6613557ae4ee2dc3598 # v1
         with:
           target: x86_64
           args: --release --locked --out dist
       - name: "Upload wheels"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: wheels-macos-x86_64
           path: dist
@@ -99,7 +99,7 @@ jobs:
           tar czvf $ARCHIVE_FILE $ARCHIVE_NAME
           shasum -a 256 $ARCHIVE_FILE > $ARCHIVE_FILE.sha256
       - name: "Upload binary"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: artifacts-macos-x86_64
           path: |
@@ -110,18 +110,18 @@ jobs:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
     runs-on: macos-14
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
           architecture: arm64
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
       - name: "Build wheels - aarch64"
-        uses: PyO3/maturin-action@v1
+        uses: PyO3/maturin-action@36db84001d74475ad1b8e6613557ae4ee2dc3598 # v1
         with:
           target: aarch64
           args: --release --locked --out dist
@@ -131,7 +131,7 @@ jobs:
           ruff --help
           python -m ruff --help
       - name: "Upload wheels"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: wheels-aarch64-apple-darwin
           path: dist
@@ -146,7 +146,7 @@ jobs:
           tar czvf $ARCHIVE_FILE $ARCHIVE_NAME
           shasum -a 256 $ARCHIVE_FILE > $ARCHIVE_FILE.sha256
       - name: "Upload binary"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: artifacts-aarch64-apple-darwin
           path: |
@@ -166,18 +166,18 @@ jobs:
           - target: aarch64-pc-windows-msvc
             arch: x64
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
           architecture: ${{ matrix.platform.arch }}
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
       - name: "Build wheels"
-        uses: PyO3/maturin-action@v1
+        uses: PyO3/maturin-action@36db84001d74475ad1b8e6613557ae4ee2dc3598 # v1
         with:
           target: ${{ matrix.platform.target }}
           args: --release --locked --out dist
@@ -192,7 +192,7 @@ jobs:
           "${MODULE_NAME}" --help
           python -m "${MODULE_NAME}" --help
       - name: "Upload wheels"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: wheels-${{ matrix.platform.target }}
           path: dist
@@ -203,7 +203,7 @@ jobs:
           7z a $ARCHIVE_FILE ./target/${{ matrix.platform.target }}/release/ruff.exe
           sha256sum $ARCHIVE_FILE > $ARCHIVE_FILE.sha256
       - name: "Upload binary"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: artifacts-${{ matrix.platform.target }}
           path: |
@@ -219,18 +219,18 @@ jobs:
           - x86_64-unknown-linux-gnu
           - i686-unknown-linux-gnu
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
           architecture: x64
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
       - name: "Build wheels"
-        uses: PyO3/maturin-action@v1
+        uses: PyO3/maturin-action@36db84001d74475ad1b8e6613557ae4ee2dc3598 # v1
         with:
           target: ${{ matrix.target }}
           manylinux: auto
@@ -242,7 +242,7 @@ jobs:
           "${MODULE_NAME}" --help
           python -m "${MODULE_NAME}" --help
       - name: "Upload wheels"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: wheels-${{ matrix.target }}
           path: dist
@@ -260,7 +260,7 @@ jobs:
           tar czvf $ARCHIVE_FILE $ARCHIVE_NAME
           shasum -a 256 $ARCHIVE_FILE > $ARCHIVE_FILE.sha256
       - name: "Upload binary"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: artifacts-${{ matrix.target }}
           path: |
@@ -294,24 +294,24 @@ jobs:
             arch: arm
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
       - name: "Build wheels"
-        uses: PyO3/maturin-action@v1
+        uses: PyO3/maturin-action@36db84001d74475ad1b8e6613557ae4ee2dc3598 # v1
         with:
           target: ${{ matrix.platform.target }}
           manylinux: auto
           docker-options: ${{ matrix.platform.maturin_docker_options }}
           args: --release --locked --out dist
-      - uses: uraimo/run-on-arch-action@v2
-        if: matrix.platform.arch != 'ppc64'
+      - uses: uraimo/run-on-arch-action@ac33288c3728ca72563c97b8b88dda5a65a84448 # v2
+        if: ${{ matrix.platform.arch != 'ppc64' && matrix.platform.arch != 'ppc64le'}}
         name: Test wheel
         with:
           arch: ${{ matrix.platform.arch == 'arm' && 'armv6' || matrix.platform.arch }}
@@ -325,7 +325,7 @@ jobs:
             pip3 install ${{ env.PACKAGE_NAME }} --no-index --find-links dist/ --force-reinstall
             ruff --help
       - name: "Upload wheels"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: wheels-${{ matrix.platform.target }}
           path: dist
@@ -343,7 +343,7 @@ jobs:
           tar czvf $ARCHIVE_FILE $ARCHIVE_NAME
           shasum -a 256 $ARCHIVE_FILE > $ARCHIVE_FILE.sha256
       - name: "Upload binary"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: artifacts-${{ matrix.platform.target }}
           path: |
@@ -359,18 +359,18 @@ jobs:
           - x86_64-unknown-linux-musl
           - i686-unknown-linux-musl
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
           architecture: x64
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
       - name: "Build wheels"
-        uses: PyO3/maturin-action@v1
+        uses: PyO3/maturin-action@36db84001d74475ad1b8e6613557ae4ee2dc3598 # v1
         with:
           target: ${{ matrix.target }}
           manylinux: musllinux_1_2
@@ -387,7 +387,7 @@ jobs:
             .venv/bin/pip3 install ${{ env.PACKAGE_NAME }} --no-index --find-links dist/ --force-reinstall
             .venv/bin/${{ env.MODULE_NAME }} --help
       - name: "Upload wheels"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: wheels-${{ matrix.target }}
           path: dist
@@ -405,7 +405,7 @@ jobs:
           tar czvf $ARCHIVE_FILE $ARCHIVE_NAME
           shasum -a 256 $ARCHIVE_FILE > $ARCHIVE_FILE.sha256
       - name: "Upload binary"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: artifacts-${{ matrix.target }}
           path: |
@@ -425,23 +425,23 @@ jobs:
             arch: armv7
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
       - name: "Build wheels"
-        uses: PyO3/maturin-action@v1
+        uses: PyO3/maturin-action@36db84001d74475ad1b8e6613557ae4ee2dc3598 # v1
         with:
           target: ${{ matrix.platform.target }}
           manylinux: musllinux_1_2
           args: --release --locked --out dist
           docker-options: ${{ matrix.platform.maturin_docker_options }}
-      - uses: uraimo/run-on-arch-action@v2
+      - uses: uraimo/run-on-arch-action@ac33288c3728ca72563c97b8b88dda5a65a84448 # v2
         name: Test wheel
         with:
           arch: ${{ matrix.platform.arch }}
@@ -454,7 +454,7 @@ jobs:
             .venv/bin/pip3 install ${{ env.PACKAGE_NAME }} --no-index --find-links dist/ --force-reinstall
             .venv/bin/${{ env.MODULE_NAME }} --help
       - name: "Upload wheels"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: wheels-${{ matrix.platform.target }}
           path: dist
@@ -472,7 +472,7 @@ jobs:
           tar czvf $ARCHIVE_FILE $ARCHIVE_NAME
           shasum -a 256 $ARCHIVE_FILE > $ARCHIVE_FILE.sha256
       - name: "Upload binary"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: artifacts-${{ matrix.platform.target }}
           path: |

.github/workflows/build-docker.yml

@@ -33,14 +33,14 @@ jobs:
           - linux/amd64
           - linux/arm64
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
           persist-credentials: false
 
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@b5ca514318bd6ebac0fb2aedd5d36ec1b5c232a2 # v3
 
-      - uses: docker/login-action@v3
+      - uses: docker/login-action@74a5d142397b4f367a81961eba4e8cd7edddf772 # v3
         with:
           registry: ghcr.io
           username: ${{ github.repository_owner }}
@@ -63,7 +63,7 @@ jobs:
 
       - name: Extract metadata (tags, labels) for Docker
         id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@902fa8ec7d6ecbf8d84d538b9b233a880e428804 # v5
         with:
           images: ${{ env.RUFF_BASE_IMG }}
           # Defining this makes sure the org.opencontainers.image.version OCI label becomes the actual release version and not the branch name
@@ -79,7 +79,7 @@ jobs:
       # Adapted from https://docs.docker.com/build/ci/github-actions/multi-platform/
       - name: Build and push by digest
         id: build
-        uses: docker/build-push-action@v6
+        uses: docker/build-push-action@471d1dc4e07e5cdedd4c2171150001c434f0b7a4 # v6
         with:
           context: .
           platforms: ${{ matrix.platform }}
@@ -96,7 +96,7 @@ jobs:
           touch "/tmp/digests/${digest#sha256:}"
 
       - name: Upload digests
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: digests-${{ env.PLATFORM_TUPLE }}
           path: /tmp/digests/*
@@ -113,17 +113,17 @@ jobs:
     if: ${{ inputs.plan != '' && !fromJson(inputs.plan).announcement_tag_is_implicit }}
     steps:
       - name: Download digests
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@cc203385981b70ca67e1cc392babf9cc229d5806 # v4
         with:
           path: /tmp/digests
           pattern: digests-*
           merge-multiple: true
 
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@b5ca514318bd6ebac0fb2aedd5d36ec1b5c232a2 # v3
 
       - name: Extract metadata (tags, labels) for Docker
         id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@902fa8ec7d6ecbf8d84d538b9b233a880e428804 # v5
         with:
           images: ${{ env.RUFF_BASE_IMG }}
           # Order is on purpose such that the label org.opencontainers.image.version has the first pattern with the full version
@@ -131,7 +131,7 @@ jobs:
             type=pep440,pattern={{ version }},value=${{ fromJson(inputs.plan).announcement_tag }}
             type=pep440,pattern={{ major }}.{{ minor }},value=${{ fromJson(inputs.plan).announcement_tag }}
 
-      - uses: docker/login-action@v3
+      - uses: docker/login-action@74a5d142397b4f367a81961eba4e8cd7edddf772 # v3
         with:
           registry: ghcr.io
           username: ${{ github.repository_owner }}
@@ -163,13 +163,13 @@ jobs:
         # Mapping of base image followed by a comma followed by one or more base tags (comma separated)
         # Note, org.opencontainers.image.version label will use the first base tag (use the most specific tag first)
         image-mapping:
-          - alpine:3.20,alpine3.20,alpine
+          - alpine:3.21,alpine3.21,alpine
           - debian:bookworm-slim,bookworm-slim,debian-slim
           - buildpack-deps:bookworm,bookworm,debian
     steps:
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@b5ca514318bd6ebac0fb2aedd5d36ec1b5c232a2 # v3
 
-      - uses: docker/login-action@v3
+      - uses: docker/login-action@74a5d142397b4f367a81961eba4e8cd7edddf772 # v3
         with:
           registry: ghcr.io
           username: ${{ github.repository_owner }}
@@ -219,7 +219,7 @@ jobs:
 
       - name: Extract metadata (tags, labels) for Docker
         id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@902fa8ec7d6ecbf8d84d538b9b233a880e428804 # v5
         # ghcr.io prefers index level annotations
         env:
           DOCKER_METADATA_ANNOTATIONS_LEVELS: index
@@ -231,7 +231,7 @@ jobs:
             ${{ env.TAG_PATTERNS }}
 
       - name: Build and push
-        uses: docker/build-push-action@v6
+        uses: docker/build-push-action@471d1dc4e07e5cdedd4c2171150001c434f0b7a4 # v6
         with:
           context: .
           platforms: linux/amd64,linux/arm64
@@ -256,17 +256,17 @@ jobs:
     if: ${{ inputs.plan != '' && !fromJson(inputs.plan).announcement_tag_is_implicit }}
     steps:
       - name: Download digests
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@cc203385981b70ca67e1cc392babf9cc229d5806 # v4
         with:
           path: /tmp/digests
           pattern: digests-*
           merge-multiple: true
 
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@b5ca514318bd6ebac0fb2aedd5d36ec1b5c232a2 # v3
 
       - name: Extract metadata (tags, labels) for Docker
         id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@902fa8ec7d6ecbf8d84d538b9b233a880e428804 # v5
         env:
           DOCKER_METADATA_ANNOTATIONS_LEVELS: index
         with:
@@ -276,7 +276,7 @@ jobs:
             type=pep440,pattern={{ version }},value=${{ fromJson(inputs.plan).announcement_tag }}
             type=pep440,pattern={{ major }}.{{ minor }},value=${{ fromJson(inputs.plan).announcement_tag }}
 
-      - uses: docker/login-action@v3
+      - uses: docker/login-action@74a5d142397b4f367a81961eba4e8cd7edddf772 # v3
         with:
           registry: ghcr.io
           username: ${{ github.repository_owner }}

.github/workflows/ci.yaml

@@ -26,83 +26,152 @@ jobs:
     runs-on: ubuntu-latest
     outputs:
       # Flag that is raised when any code that affects parser is changed
-      parser: ${{ steps.changed.outputs.parser_any_changed }}
+      parser: ${{ steps.check_parser.outputs.changed }}
       # Flag that is raised when any code that affects linter is changed
-      linter: ${{ steps.changed.outputs.linter_any_changed }}
+      linter: ${{ steps.check_linter.outputs.changed }}
       # Flag that is raised when any code that affects formatter is changed
-      formatter: ${{ steps.changed.outputs.formatter_any_changed }}
+      formatter: ${{ steps.check_formatter.outputs.changed }}
       # Flag that is raised when any code is changed
       # This is superset of the linter and formatter
-      code: ${{ steps.changed.outputs.code_any_changed }}
+      code: ${{ steps.check_code.outputs.changed }}
       # Flag that is raised when any code that affects the fuzzer is changed
-      fuzz: ${{ steps.changed.outputs.fuzz_any_changed }}
+      fuzz: ${{ steps.check_fuzzer.outputs.changed }}
+
+      # Flag that is set to "true" when code related to the playground changes.
+      playground: ${{ steps.check_playground.outputs.changed }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           fetch-depth: 0
           persist-credentials: false
 
-      - uses: tj-actions/changed-files@v45
-        id: changed
-        with:
-          files_yaml: |
-            parser:
-              - Cargo.toml
-              - Cargo.lock
-              - crates/ruff_python_trivia/**
-              - crates/ruff_source_file/**
-              - crates/ruff_text_size/**
-              - crates/ruff_python_ast/**
-              - crates/ruff_python_parser/**
-              - python/py-fuzzer/**
-              - .github/workflows/ci.yaml
+      - name: Determine merge base
+        id: merge_base
+        env:
+          BASE_REF: ${{ github.event.pull_request.base.ref || 'main' }}
+        run: |
+          sha=$(git merge-base HEAD "origin/${BASE_REF}")
+          echo "sha=${sha}" >> "$GITHUB_OUTPUT"
 
-            linter:
-              - Cargo.toml
-              - Cargo.lock
-              - crates/**
-              - "!crates/red_knot*/**"
-              - "!crates/ruff_python_formatter/**"
-              - "!crates/ruff_formatter/**"
-              - "!crates/ruff_dev/**"
-              - scripts/*
-              - python/**
-              - .github/workflows/ci.yaml
+      - name: Check if the parser code changed
+        id: check_parser
+        env:
+          MERGE_BASE: ${{ steps.merge_base.outputs.sha }}
+        run: |
+          if git diff --quiet "${MERGE_BASE}...HEAD" -- \
+            ':Cargo.toml' \
+            ':Cargo.lock' \
+            ':crates/ruff_python_trivia/**' \
+            ':crates/ruff_source_file/**' \
+            ':crates/ruff_text_size/**' \
+            ':crates/ruff_python_ast/**' \
+            ':crates/ruff_python_parser/**' \
+            ':python/py-fuzzer/**' \
+            ':.github/workflows/ci.yaml' \
+          ; then
+              echo "changed=false" >> "$GITHUB_OUTPUT"
+          else
+              echo "changed=true" >> "$GITHUB_OUTPUT"
+          fi
 
-            formatter:
-              - Cargo.toml
-              - Cargo.lock
-              - crates/ruff_python_formatter/**
-              - crates/ruff_formatter/**
-              - crates/ruff_python_trivia/**
-              - crates/ruff_python_ast/**
-              - crates/ruff_source_file/**
-              - crates/ruff_python_index/**
-              - crates/ruff_text_size/**
-              - crates/ruff_python_parser/**
-              - crates/ruff_dev/**
-              - scripts/*
-              - python/**
-              - .github/workflows/ci.yaml
+      - name: Check if the linter code changed
+        id: check_linter
+        env:
+          MERGE_BASE: ${{ steps.merge_base.outputs.sha }}
+        run: |
+          if git diff --quiet "${MERGE_BASE}...HEAD" -- ':Cargo.toml' \
+            ':Cargo.lock' \
+            ':crates/**' \
+            ':!crates/red_knot*/**' \
+            ':!crates/ruff_python_formatter/**' \
+            ':!crates/ruff_formatter/**' \
+            ':!crates/ruff_dev/**' \
+            ':!crates/ruff_db/**' \
+            ':scripts/*' \
+            ':python/**' \
+            ':.github/workflows/ci.yaml' \
+          ; then
+              echo "changed=false" >> "$GITHUB_OUTPUT"
+          else
+              echo "changed=true" >> "$GITHUB_OUTPUT"
+          fi
 
-            fuzz:
-              - fuzz/Cargo.toml
-              - fuzz/Cargo.lock
-              - fuzz/fuzz_targets/**
+      - name: Check if the formatter code changed
+        id: check_formatter
+        env:
+          MERGE_BASE: ${{ steps.merge_base.outputs.sha }}
+        run: |
+          if git diff --quiet "${MERGE_BASE}...HEAD" -- ':Cargo.toml' \
+            ':Cargo.lock' \
+            ':crates/ruff_python_formatter/**' \
+            ':crates/ruff_formatter/**' \
+            ':crates/ruff_python_trivia/**' \
+            ':crates/ruff_python_ast/**' \
+            ':crates/ruff_source_file/**' \
+            ':crates/ruff_python_index/**' \
+            ':crates/ruff_python_index/**' \
+            ':crates/ruff_text_size/**' \
+            ':crates/ruff_python_parser/**' \
+            ':scripts/*' \
+            ':python/**' \
+            ':.github/workflows/ci.yaml' \
+          ; then
+              echo "changed=false" >> "$GITHUB_OUTPUT"
+          else
+              echo "changed=true" >> "$GITHUB_OUTPUT"
+          fi
 
-            code:
-              - "**/*"
-              - "!**/*.md"
-              - "crates/red_knot_python_semantic/resources/mdtest/**/*.md"
-              - "!docs/**"
-              - "!assets/**"
+      - name: Check if the fuzzer code changed
+        id: check_fuzzer
+        env:
+          MERGE_BASE: ${{ steps.merge_base.outputs.sha }}
+        run: |
+          if git diff --quiet "${MERGE_BASE}...HEAD" -- ':Cargo.toml' \
+            ':Cargo.lock' \
+            ':fuzz/fuzz_targets/**' \
+            ':.github/workflows/ci.yaml' \
+          ; then
+              echo "changed=false" >> "$GITHUB_OUTPUT"
+          else
+              echo "changed=true" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Check if there was any code related change
+        id: check_code
+        env:
+          MERGE_BASE: ${{ steps.merge_base.outputs.sha }}
+        run: |
+          if git diff --quiet "${MERGE_BASE}...HEAD" -- ':**/*' \
+            ':!**/*.md' \
+            ':crates/red_knot_python_semantic/resources/mdtest/**/*.md' \
+            ':!docs/**' \
+            ':!assets/**' \
+            ':.github/workflows/ci.yaml' \
+          ; then
+              echo "changed=false" >> "$GITHUB_OUTPUT"
+          else
+              echo "changed=true" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Check if there was any playground related change
+        id: check_playground
+        env:
+          MERGE_BASE: ${{ steps.merge_base.outputs.sha }}
+        run: |
+          if git diff --quiet "${MERGE_BASE}...HEAD" -- \
+            ':playground/**' \
+          ; then
+              echo "changed=false" >> "$GITHUB_OUTPUT"
+          else
+              echo "changed=true" >> "$GITHUB_OUTPUT"
+          fi
 
   cargo-fmt:
     name: "cargo fmt"
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
       - name: "Install Rust toolchain"
@@ -116,10 +185,10 @@ jobs:
     if: ${{ needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main' }}
     timeout-minutes: 20
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: "Install Rust toolchain"
         run: |
           rustup component add clippy
@@ -136,20 +205,20 @@ jobs:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-test') && (needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main') }}
     timeout-minutes: 20
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
         uses: rui314/setup-mold@v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@v2
+        uses: taiki-e/install-action@2c41309d51ede152b6f2ee6bf3b71e6dc9a8b7df # v2
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
-        uses: taiki-e/install-action@v2
+        uses: taiki-e/install-action@2c41309d51ede152b6f2ee6bf3b71e6dc9a8b7df # v2
         with:
           tool: cargo-insta
       - name: "Run tests"
@@ -170,7 +239,7 @@ jobs:
         env:
           # Setting RUSTDOCFLAGS because `cargo doc --check` isn't yet implemented (https://github.com/rust-lang/cargo/issues/10025).
           RUSTDOCFLAGS: "-D warnings"
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: ruff
           path: target/debug/ruff
@@ -182,20 +251,20 @@ jobs:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-test') && (needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main') }}
     timeout-minutes: 20
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
         uses: rui314/setup-mold@v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@v2
+        uses: taiki-e/install-action@2c41309d51ede152b6f2ee6bf3b71e6dc9a8b7df # v2
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
-        uses: taiki-e/install-action@v2
+        uses: taiki-e/install-action@2c41309d51ede152b6f2ee6bf3b71e6dc9a8b7df # v2
         with:
           tool: cargo-insta
       - name: "Run tests"
@@ -211,14 +280,14 @@ jobs:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-test') && (needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main') }}
     timeout-minutes: 20
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@v2
+        uses: taiki-e/install-action@2c41309d51ede152b6f2ee6bf3b71e6dc9a8b7df # v2
         with:
           tool: cargo-nextest
       - name: "Run tests"
@@ -238,18 +307,18 @@ jobs:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-test') && (needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main') }}
     timeout-minutes: 10
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: "Install Rust toolchain"
         run: rustup target add wasm32-unknown-unknown
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e # v4
         with:
           node-version: 20
           cache: "npm"
           cache-dependency-path: playground/package-lock.json
-      - uses: jetli/wasm-pack-action@v0.4.0
+      - uses: jetli/wasm-pack-action@0d096b08b4e5a7de8c28de67e11e945404e9eefa # v0.4.0
         with:
           version: v0.13.1
       - name: "Test ruff_wasm"
@@ -267,10 +336,10 @@ jobs:
     if: ${{ github.ref == 'refs/heads/main' }}
     timeout-minutes: 20
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
@@ -285,15 +354,15 @@ jobs:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-test') && (needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main') }}
     timeout-minutes: 20
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: SebRollen/toml-action@v1.2.0
+      - uses: SebRollen/toml-action@b1b3628f55fc3a28208d4203ada8b737e9687876 # v1.2.0
         id: msrv
         with:
           file: "Cargo.toml"
           field: "workspace.package.rust-version"
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: "Install Rust toolchain"
         env:
           MSRV: ${{ steps.msrv.outputs.value }}
@@ -301,11 +370,11 @@ jobs:
       - name: "Install mold"
         uses: rui314/setup-mold@v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@v2
+        uses: taiki-e/install-action@2c41309d51ede152b6f2ee6bf3b71e6dc9a8b7df # v2
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
-        uses: taiki-e/install-action@v2
+        uses: taiki-e/install-action@2c41309d51ede152b6f2ee6bf3b71e6dc9a8b7df # v2
         with:
           tool: cargo-insta
       - name: "Run tests"
@@ -322,10 +391,10 @@ jobs:
     if: ${{ github.ref == 'refs/heads/main' || needs.determine_changes.outputs.fuzz == 'true' || needs.determine_changes.outputs.code == 'true' }}
     timeout-minutes: 10
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
         with:
           workspaces: "fuzz -> target"
       - name: "Install Rust toolchain"
@@ -350,11 +419,11 @@ jobs:
     env:
       FORCE_COLOR: 1
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: astral-sh/setup-uv@v5
-      - uses: actions/download-artifact@v4
+      - uses: astral-sh/setup-uv@f94ec6bedd8674c4426838e6b50417d36b6ab231 # v5
+      - uses: actions/download-artifact@cc203385981b70ca67e1cc392babf9cc229d5806 # v4
         name: Download Ruff binary to test
         id: download-cached-binary
         with:
@@ -384,10 +453,10 @@ jobs:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-test') && (needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main') }}
     timeout-minutes: 5
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: "Install Rust toolchain"
         run: rustup component add rustfmt
       # Run all code generation scripts, and verify that the current output is
@@ -416,21 +485,21 @@ jobs:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-test') && github.event_name == 'pull_request' && needs.determine_changes.outputs.code == 'true' }}
     timeout-minutes: 20
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
 
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@cc203385981b70ca67e1cc392babf9cc229d5806 # v4
         name: Download comparison Ruff binary
         id: ruff-target
         with:
           name: ruff
           path: target/debug
 
-      - uses: dawidd6/action-download-artifact@v8
+      - uses: dawidd6/action-download-artifact@20319c5641d495c8a52e688b7dc5fada6c3a9fbc # v8
         name: Download baseline Ruff binary
         with:
           name: ruff
@@ -518,13 +587,13 @@ jobs:
         run: |
           echo ${{ github.event.number }} > pr-number
 
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         name: Upload PR Number
         with:
           name: pr-number
           path: pr-number
 
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         name: Upload Results
         with:
           name: ecosystem-result
@@ -536,7 +605,7 @@ jobs:
     needs: determine_changes
     if: ${{ needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main' }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
       - uses: cargo-bins/cargo-binstall@main
@@ -549,18 +618,18 @@ jobs:
     timeout-minutes: 20
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-test') }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
           architecture: x64
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
       - name: "Build wheels"
-        uses: PyO3/maturin-action@v1
+        uses: PyO3/maturin-action@36db84001d74475ad1b8e6613557ae4ee2dc3598 # v1
         with:
           args: --out dist
       - name: "Test wheel"
@@ -576,19 +645,19 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install pre-commit"
         run: pip install pre-commit
       - name: "Cache pre-commit"
-        uses: actions/cache@v4
+        uses: actions/cache@d4323d4df104b026a6aa633fdb11d772146be0bf # v4
         with:
           path: ~/.cache/pre-commit
           key: pre-commit-${{ hashFiles('.pre-commit-config.yaml') }}
@@ -610,22 +679,22 @@ jobs:
     env:
       MKDOCS_INSIDERS_SSH_KEY_EXISTS: ${{ secrets.MKDOCS_INSIDERS_SSH_KEY != '' }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: "3.13"
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: "Add SSH key"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS == 'true' }}
-        uses: webfactory/ssh-agent@v0.9.0
+        uses: webfactory/ssh-agent@dc588b651fe13675774614f8e6a936a468676387 # v0.9.0
         with:
           ssh-private-key: ${{ secrets.MKDOCS_INSIDERS_SSH_KEY }}
       - name: "Install Rust toolchain"
         run: rustup show
       - name: Install uv
-        uses: astral-sh/setup-uv@v5
+        uses: astral-sh/setup-uv@f94ec6bedd8674c4426838e6b50417d36b6ab231 # v5
       - name: "Install Insiders dependencies"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS == 'true' }}
         run: uv pip install -r docs/requirements-insiders.txt --system
@@ -652,10 +721,10 @@ jobs:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-test') && (needs.determine_changes.outputs.formatter == 'true' || github.ref == 'refs/heads/main') }}
     timeout-minutes: 10
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Run checks"
@@ -674,21 +743,21 @@ jobs:
       - determine_changes
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-test') && (needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main') }}
     steps:
-      - uses: extractions/setup-just@v2
+      - uses: extractions/setup-just@dd310ad5a97d8e7b41793f8ef055398d51ad4de6 # v2
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         name: "Download ruff-lsp source"
         with:
           persist-credentials: false
           repository: "astral-sh/ruff-lsp"
 
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
 
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@cc203385981b70ca67e1cc392babf9cc229d5806 # v4
         name: Download development ruff binary
         id: ruff-target
         with:
@@ -711,6 +780,39 @@ jobs:
 
           just test
 
+  check-playground:
+    name: "check playground"
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    needs:
+      - determine_changes
+    if: ${{ (needs.determine_changes.outputs.playground == 'true') }}
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
+        with:
+          persist-credentials: false
+      - name: "Install Rust toolchain"
+        run: rustup target add wasm32-unknown-unknown
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
+      - uses: actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e # v4
+        with:
+          node-version: 22
+          cache: "npm"
+          cache-dependency-path: playground/package-lock.json
+      - uses: jetli/wasm-bindgen-action@20b33e20595891ab1a0ed73145d8a21fc96e7c29 # v0.2.0
+      - name: "Install Node dependencies"
+        run: npm ci
+        working-directory: playground
+      - name: "Build playgrounds"
+        run: npm run dev:wasm
+        working-directory: playground
+      - name: "Run TypeScript checks"
+        run: npm run check
+        working-directory: playground
+      - name: "Check formatting"
+        run: npm run fmt:check
+        working-directory: playground
+
   benchmarks:
     runs-on: ubuntu-24.04
     needs: determine_changes
@@ -718,17 +820,17 @@ jobs:
     timeout-minutes: 20
     steps:
       - name: "Checkout Branch"
-        uses: actions/checkout@v4
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
 
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
 
       - name: "Install Rust toolchain"
         run: rustup show
 
       - name: "Install codspeed"
-        uses: taiki-e/install-action@v2
+        uses: taiki-e/install-action@2c41309d51ede152b6f2ee6bf3b71e6dc9a8b7df # v2
         with:
           tool: cargo-codspeed
 
@@ -736,7 +838,7 @@ jobs:
         run: cargo codspeed build --features codspeed -p ruff_benchmark
 
       - name: "Run benchmarks"
-        uses: CodSpeedHQ/action@v3
+        uses: CodSpeedHQ/action@0010eb0ca6e89b80c88e8edaaa07cfe5f3e6664d # v3
         with:
           run: cargo codspeed run
           token: ${{ secrets.CODSPEED_TOKEN }}

.github/workflows/daily_fuzz.yaml

@@ -31,15 +31,15 @@ jobs:
     # Don't run the cron job on forks:
     if: ${{ github.repository == 'astral-sh/ruff' || github.event_name != 'schedule' }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
-      - uses: astral-sh/setup-uv@v5
+      - uses: astral-sh/setup-uv@f94ec6bedd8674c4426838e6b50417d36b6ab231 # v5
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
         uses: rui314/setup-mold@v1
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: Build ruff
         # A debug build means the script runs slower once it gets started,
         # but this is outweighed by the fact that a release build takes *much* longer to compile in CI
@@ -65,7 +65,7 @@ jobs:
     permissions:
       issues: write
     steps:
-      - uses: actions/github-script@v7
+      - uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           script: |

.github/workflows/daily_property_tests.yaml

@@ -30,14 +30,14 @@ jobs:
     # Don't run the cron job on forks:
     if: ${{ github.repository == 'astral-sh/ruff' || github.event_name != 'schedule' }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
         uses: rui314/setup-mold@v1
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
       - name: Build Red Knot
         # A release build takes longer (2 min vs 1 min), but the property tests run much faster in release
         # mode (1.5 min vs 14 min), so the overall time is shorter with a release build.
@@ -59,7 +59,7 @@ jobs:
     permissions:
       issues: write
     steps:
-      - uses: actions/github-script@v7
+      - uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           script: |

.github/workflows/mypy_primer.yaml

@@ -28,21 +28,25 @@ jobs:
     runs-on: ubuntu-24.04
     timeout-minutes: 20
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           path: ruff
           fetch-depth: 0
           persist-credentials: false
 
       - name: Install the latest version of uv
-        uses: astral-sh/setup-uv@v5
+        uses: astral-sh/setup-uv@f94ec6bedd8674c4426838e6b50417d36b6ab231 # v5
 
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
         with:
           workspaces: "ruff"
       - name: Install Rust toolchain
         run: rustup show
 
+      - name: Install mypy_primer
+        run: |
+          uv tool install "git+https://github.com/astral-sh/mypy_primer.git@add-red-knot-support"
+
       - name: Run mypy_primer
         shell: bash
         run: |
@@ -58,18 +62,15 @@ jobs:
 
           cd ..
 
-          echo "Running mypy_primer"
-
-          (
-            uvx --verbose --from "git+https://github.com/astral-sh/mypy_primer.git@add-red-knot-support" mypy_primer \
-              --repo ruff \
-              --type-checker knot \
-              --old base_commit \
-              --new "$GITHUB_SHA" \
-              --project-selector '/(mypy_primer|black|pyp|git-revise|zipp|arrow)$' \
-              --output concise \
-              --debug > mypy_primer.diff
-          ) || [ $? -eq 1 ]
+          # Allow the exit code to be 0 or 1, only fail for actual mypy_primer crashes/bugs
+          uvx mypy_primer \
+            --repo ruff \
+            --type-checker knot \
+            --old base_commit \
+            --new "$GITHUB_SHA" \
+            --project-selector '/(mypy_primer|black|pyp|git-revise|zipp|arrow|isort|itsdangerous|rich|packaging|pybind11|pyinstrument)$' \
+            --output concise \
+            --debug > mypy_primer.diff || [ $? -eq 1 ]
 
           # Output diff with ANSI color codes
           cat mypy_primer.diff
@@ -80,13 +81,13 @@ jobs:
           echo ${{ github.event.number }} > pr-number
 
       - name: Upload diff
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: mypy_primer_diff
           path: mypy_primer.diff
 
       - name: Upload pr-number
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: pr-number
           path: pr-number

.github/workflows/mypy_primer_comment.yaml

@@ -16,7 +16,7 @@ jobs:
     permissions:
       pull-requests: write
     steps:
-      - uses: dawidd6/action-download-artifact@v8
+      - uses: dawidd6/action-download-artifact@20319c5641d495c8a52e688b7dc5fada6c3a9fbc # v8
         name: Download PR number
         with:
           name: pr-number
@@ -32,7 +32,7 @@ jobs:
             echo "pr-number=$(<pr-number)" >> "$GITHUB_OUTPUT"
           fi
 
-      - uses: dawidd6/action-download-artifact@v8
+      - uses: dawidd6/action-download-artifact@20319c5641d495c8a52e688b7dc5fada6c3a9fbc # v8
         name: "Download mypy_primer results"
         id: download-mypy_primer_diff
         if: steps.pr-number.outputs.pr-number
@@ -79,7 +79,7 @@ jobs:
           echo 'EOF' >> "$GITHUB_OUTPUT"
 
       - name: Find existing comment
-        uses: peter-evans/find-comment@v3
+        uses: peter-evans/find-comment@3eae4d37986fb5a8592848f6a574fdf654e61f9e # v3
         if: steps.generate-comment.outcome == 'success'
         id: find-comment
         with:
@@ -89,7 +89,7 @@ jobs:
 
       - name: Create or update comment
         if: steps.find-comment.outcome == 'success'
-        uses: peter-evans/create-or-update-comment@v4
+        uses: peter-evans/create-or-update-comment@71345be0265236311c031f5c7866368bd1eff043 # v4
         with:
           comment-id: ${{ steps.find-comment.outputs.comment-id }}
           issue-number: ${{ steps.pr-number.outputs.pr-number }}

.github/workflows/notify-dependents.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: "Update pre-commit mirror"
-        uses: actions/github-script@v7
+        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7
         with:
           github-token: ${{ secrets.RUFF_PRE_COMMIT_PAT }}
           script: |

.github/workflows/pr-comment.yaml

@@ -16,7 +16,7 @@ jobs:
     permissions:
       pull-requests: write
     steps:
-      - uses: dawidd6/action-download-artifact@v8
+      - uses: dawidd6/action-download-artifact@20319c5641d495c8a52e688b7dc5fada6c3a9fbc # v8
         name: Download pull request number
         with:
           name: pr-number
@@ -32,7 +32,7 @@ jobs:
             echo "pr-number=$(<pr-number)" >> "$GITHUB_OUTPUT"
           fi
 
-      - uses: dawidd6/action-download-artifact@v8
+      - uses: dawidd6/action-download-artifact@20319c5641d495c8a52e688b7dc5fada6c3a9fbc # v8
         name: "Download ecosystem results"
         id: download-ecosystem-result
         if: steps.pr-number.outputs.pr-number
@@ -70,7 +70,7 @@ jobs:
           echo 'EOF' >> "$GITHUB_OUTPUT"
 
       - name: Find existing comment
-        uses: peter-evans/find-comment@v3
+        uses: peter-evans/find-comment@3eae4d37986fb5a8592848f6a574fdf654e61f9e # v3
         if: steps.generate-comment.outcome == 'success'
         id: find-comment
         with:
@@ -80,7 +80,7 @@ jobs:
 
       - name: Create or update comment
         if: steps.find-comment.outcome == 'success'
-        uses: peter-evans/create-or-update-comment@v4
+        uses: peter-evans/create-or-update-comment@71345be0265236311c031f5c7866368bd1eff043 # v4
         with:
           comment-id: ${{ steps.find-comment.outputs.comment-id }}
           issue-number: ${{ steps.pr-number.outputs.pr-number }}

.github/workflows/publish-docs.yml

@@ -23,12 +23,12 @@ jobs:
     env:
       MKDOCS_INSIDERS_SSH_KEY_EXISTS: ${{ secrets.MKDOCS_INSIDERS_SSH_KEY != '' }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           ref: ${{ inputs.ref }}
           persist-credentials: true
 
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5
         with:
           python-version: 3.12
 
@@ -61,14 +61,14 @@ jobs:
 
       - name: "Add SSH key"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS == 'true' }}
-        uses: webfactory/ssh-agent@v0.9.0
+        uses: webfactory/ssh-agent@dc588b651fe13675774614f8e6a936a468676387 # v0.9.0
         with:
           ssh-private-key: ${{ secrets.MKDOCS_INSIDERS_SSH_KEY }}
 
       - name: "Install Rust toolchain"
         run: rustup show
 
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2
 
       - name: "Install Insiders dependencies"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS == 'true' }}

.github/workflows/publish-knot-playground.yml

@@ -0,0 +1,58 @@
+# Publish the Red Knot playground.
+name: "[Knot Playground] Release"
+
+permissions: {}
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - "crates/red_knot*/**"
+      - "crates/ruff_db"
+      - "crates/ruff_python_ast"
+      - "crates/ruff_python_parser"
+      - "playground"
+      - ".github/workflows/publish-knot-playground.yml"
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref_name }}
+  cancel-in-progress: true
+
+env:
+  CARGO_INCREMENTAL: 0
+  CARGO_NET_RETRY: 10
+  CARGO_TERM_COLOR: always
+  RUSTUP_MAX_RETRIES: 10
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    env:
+      CF_API_TOKEN_EXISTS: ${{ secrets.CF_API_TOKEN != '' }}
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
+        with:
+          persist-credentials: false
+      - name: "Install Rust toolchain"
+        run: rustup target add wasm32-unknown-unknown
+      - uses: actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e # v4
+        with:
+          node-version: 22
+      - uses: jetli/wasm-bindgen-action@20b33e20595891ab1a0ed73145d8a21fc96e7c29 # v0.2.0
+      - name: "Install Node dependencies"
+        run: npm ci
+        working-directory: playground
+      - name: "Run TypeScript checks"
+        run: npm run check
+        working-directory: playground
+      - name: "Build Knot playground"
+        run: npm run build --workspace knot-playground
+        working-directory: playground
+      - name: "Deploy to Cloudflare Pages"
+        if: ${{ env.CF_API_TOKEN_EXISTS == 'true' }}
+        uses: cloudflare/wrangler-action@da0e0dfe58b7a431659754fdf3f186c529afbe65 # v3.14.1
+        with:
+          apiToken: ${{ secrets.CF_API_TOKEN }}
+          accountId: ${{ secrets.CF_ACCOUNT_ID }}
+          # `github.head_ref` is only set during pull requests and for manual runs or tags we use `main` to deploy to production
+          command: pages deploy playground/knot/dist --project-name=knot-playground --branch ${{ github.head_ref || 'main' }} --commit-hash ${GITHUB_SHA}

.github/workflows/publish-playground.yml

@@ -24,36 +24,31 @@ jobs:
     env:
       CF_API_TOKEN_EXISTS: ${{ secrets.CF_API_TOKEN != '' }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup target add wasm32-unknown-unknown
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e # v4
         with:
-          node-version: 20
+          node-version: 22
           cache: "npm"
           cache-dependency-path: playground/package-lock.json
-      - uses: jetli/wasm-pack-action@v0.4.0
-        with:
-          version: v0.13.1
-      - uses: jetli/wasm-bindgen-action@v0.2.0
-      - name: "Run wasm-pack"
-        run: wasm-pack build --target web --out-dir ../../playground/src/pkg crates/ruff_wasm
+      - uses: jetli/wasm-bindgen-action@20b33e20595891ab1a0ed73145d8a21fc96e7c29 # v0.2.0
       - name: "Install Node dependencies"
         run: npm ci
         working-directory: playground
       - name: "Run TypeScript checks"
         run: npm run check
         working-directory: playground
-      - name: "Build JavaScript bundle"
-        run: npm run build
+      - name: "Build Ruff playground"
+        run: npm run build --workspace ruff-playground
         working-directory: playground
       - name: "Deploy to Cloudflare Pages"
         if: ${{ env.CF_API_TOKEN_EXISTS == 'true' }}
-        uses: cloudflare/wrangler-action@v3.14.0
+        uses: cloudflare/wrangler-action@da0e0dfe58b7a431659754fdf3f186c529afbe65 # v3.14.1
         with:
           apiToken: ${{ secrets.CF_API_TOKEN }}
           accountId: ${{ secrets.CF_ACCOUNT_ID }}
           # `github.head_ref` is only set during pull requests and for manual runs or tags we use `main` to deploy to production
-          command: pages deploy playground/dist --project-name=ruff-playground --branch ${{ github.head_ref || 'main' }} --commit-hash ${GITHUB_SHA}
+          command: pages deploy playground/ruff/dist --project-name=ruff-playground --branch ${{ github.head_ref || 'main' }} --commit-hash ${GITHUB_SHA}

.github/workflows/publish-pypi.yml

@@ -22,8 +22,8 @@ jobs:
       id-token: write
     steps:
       - name: "Install uv"
-        uses: astral-sh/setup-uv@v5
-      - uses: actions/download-artifact@v4
+        uses: astral-sh/setup-uv@f94ec6bedd8674c4426838e6b50417d36b6ab231 # v5
+      - uses: actions/download-artifact@cc203385981b70ca67e1cc392babf9cc229d5806 # v4
         with:
           pattern: wheels-*
           path: wheels

.github/workflows/publish-wasm.yml

@@ -29,15 +29,15 @@ jobs:
         target: [web, bundler, nodejs]
       fail-fast: false
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup target add wasm32-unknown-unknown
-      - uses: jetli/wasm-pack-action@v0.4.0
+      - uses: jetli/wasm-pack-action@0d096b08b4e5a7de8c28de67e11e945404e9eefa # v0.4.0
         with:
           version: v0.13.1
-      - uses: jetli/wasm-bindgen-action@v0.2.0
+      - uses: jetli/wasm-bindgen-action@20b33e20595891ab1a0ed73145d8a21fc96e7c29 # v0.2.0
       - name: "Run wasm-pack build"
         run: wasm-pack build --target ${{ matrix.target }} crates/ruff_wasm
       - name: "Rename generated package"
@@ -45,7 +45,7 @@ jobs:
           jq '.name="@astral-sh/ruff-wasm-${{ matrix.target }}"' crates/ruff_wasm/pkg/package.json > /tmp/package.json
           mv /tmp/package.json crates/ruff_wasm/pkg
       - run: cp LICENSE crates/ruff_wasm/pkg # wasm-pack does not put the LICENSE file in the pkg
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e # v4
         with:
           node-version: 20
           registry-url: "https://registry.npmjs.org"

.github/workflows/release.yml

@@ -50,7 +50,7 @@ on:
 jobs:
   # Run 'dist plan' (or host) to determine what tasks we need to do
   plan:
-    runs-on: "ubuntu-20.04"
+    runs-on: "depot-ubuntu-latest-4"
     outputs:
       val: ${{ steps.plan.outputs.manifest }}
       tag: ${{ (inputs.tag != 'dry-run' && inputs.tag) || '' }}
@@ -59,7 +59,7 @@ jobs:
     env:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
       - name: Install dist
@@ -68,7 +68,7 @@ jobs:
         shell: bash
         run: "curl --proto '=https' --tlsv1.2 -LsSf https://github.com/axodotdev/cargo-dist/releases/download/v0.25.2-prerelease.3/cargo-dist-installer.sh | sh"
       - name: Cache dist
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: cargo-dist-cache
           path: ~/.cargo/bin/dist
@@ -84,7 +84,7 @@ jobs:
           cat plan-dist-manifest.json
           echo "manifest=$(jq -c "." plan-dist-manifest.json)" >> "$GITHUB_OUTPUT"
       - name: "Upload dist-manifest.json"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: artifacts-plan-dist-manifest
           path: plan-dist-manifest.json
@@ -116,23 +116,23 @@ jobs:
       - plan
       - custom-build-binaries
       - custom-build-docker
-    runs-on: "ubuntu-20.04"
+    runs-on: "depot-ubuntu-latest-4"
     env:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       BUILD_MANIFEST_NAME: target/distrib/global-dist-manifest.json
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
       - name: Install cached dist
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@cc203385981b70ca67e1cc392babf9cc229d5806 # v4
         with:
           name: cargo-dist-cache
           path: ~/.cargo/bin/
       - run: chmod +x ~/.cargo/bin/dist
       # Get all the local artifacts for the global tasks to use (for e.g. checksums)
       - name: Fetch local artifacts
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@cc203385981b70ca67e1cc392babf9cc229d5806 # v4
         with:
           pattern: artifacts-*
           path: target/distrib/
@@ -150,7 +150,7 @@ jobs:
 
           cp dist-manifest.json "$BUILD_MANIFEST_NAME"
       - name: "Upload artifacts"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           name: artifacts-build-global
           path: |
@@ -167,22 +167,22 @@ jobs:
     if: ${{ always() && needs.plan.outputs.publishing == 'true' && (needs.build-global-artifacts.result == 'skipped' || needs.build-global-artifacts.result == 'success') && (needs.custom-build-binaries.result == 'skipped' || needs.custom-build-binaries.result == 'success') && (needs.custom-build-docker.result == 'skipped' || needs.custom-build-docker.result == 'success') }}
     env:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-    runs-on: "ubuntu-20.04"
+    runs-on: "depot-ubuntu-latest-4"
     outputs:
       val: ${{ steps.host.outputs.manifest }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
       - name: Install cached dist
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@cc203385981b70ca67e1cc392babf9cc229d5806 # v4
         with:
           name: cargo-dist-cache
           path: ~/.cargo/bin/
       - run: chmod +x ~/.cargo/bin/dist
       # Fetch artifacts from scratch-storage
       - name: Fetch artifacts
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@cc203385981b70ca67e1cc392babf9cc229d5806 # v4
         with:
           pattern: artifacts-*
           path: target/distrib/
@@ -196,7 +196,7 @@ jobs:
           cat dist-manifest.json
           echo "manifest=$(jq -c "." dist-manifest.json)" >> "$GITHUB_OUTPUT"
       - name: "Upload dist-manifest.json"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@4cec3d8aa04e39d1a68397de0c4cd6fb9dce8ec1 # v4
         with:
           # Overwrite the previous copy
           name: artifacts-dist-manifest
@@ -242,16 +242,16 @@ jobs:
     # still allowing individual publish jobs to skip themselves (for prereleases).
     # "host" however must run to completion, no skipping allowed!
     if: ${{ always() && needs.host.result == 'success' && (needs.custom-publish-pypi.result == 'skipped' || needs.custom-publish-pypi.result == 'success') && (needs.custom-publish-wasm.result == 'skipped' || needs.custom-publish-wasm.result == 'success') }}
-    runs-on: "ubuntu-20.04"
+    runs-on: "depot-ubuntu-latest-4"
     env:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with:
           submodules: recursive
       # Create a GitHub Release while uploading all files to it
       - name: "Download GitHub Artifacts"
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@cc203385981b70ca67e1cc392babf9cc229d5806 # v4
         with:
           pattern: artifacts-*
           path: artifacts

.github/workflows/sync_typeshed.yaml

@@ -21,12 +21,12 @@ jobs:
       contents: write
       pull-requests: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         name: Checkout Ruff
         with:
           path: ruff
           persist-credentials: true
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         name: Checkout typeshed
         with:
           repository: python/typeshed
@@ -70,7 +70,7 @@ jobs:
     permissions:
       issues: write
     steps:
-      - uses: actions/github-script@v7
+      - uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           script: |

.ignore

@@ -0,0 +1 @@
+!/.github/

.pre-commit-config.yaml

@@ -19,7 +19,7 @@ exclude: |
 
 repos:
   - repo: https://github.com/abravalheri/validate-pyproject
-    rev: v0.23
+    rev: v0.24
     hooks:
       - id: validate-pyproject
 
@@ -60,7 +60,7 @@ repos:
           - black==25.1.0
 
   - repo: https://github.com/crate-ci/typos
-    rev: v1.30.0
+    rev: v1.30.2
     hooks:
       - id: typos
 
@@ -74,7 +74,7 @@ repos:
         pass_filenames: false # This makes it a lot faster
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.9.9
+    rev: v0.11.0
     hooks:
       - id: ruff-format
       - id: ruff
@@ -84,7 +84,7 @@ repos:
 
   # Prettier
   - repo: https://github.com/rbubley/mirrors-prettier
-    rev: v3.5.2
+    rev: v3.5.3
     hooks:
       - id: prettier
         types: [yaml]
@@ -92,12 +92,12 @@ repos:
   # zizmor detects security vulnerabilities in GitHub Actions workflows.
   # Additional configuration for the tool is found in `.github/zizmor.yml`
   - repo: https://github.com/woodruffw/zizmor-pre-commit
-    rev: v1.4.1
+    rev: v1.5.1
     hooks:
       - id: zizmor
 
   - repo: https://github.com/python-jsonschema/check-jsonschema
-    rev: 0.31.2
+    rev: 0.31.3
     hooks:
       - id: check-github-workflows
 

BREAKING_CHANGES.md

@@ -1,5 +1,55 @@
 # Breaking Changes
 
+## 0.11.0
+
+This is a follow-up to release 0.10.0. Because of a mistake in the release process, the `requires-python` inference changes were not included in that release. Ruff 0.11.0 now includes this change as well as the stabilization of the preview behavior for `PGH004`.
+
+- **Changes to how the Python version is inferred when a `target-version` is not specified** ([#16319](https://github.com/astral-sh/ruff/pull/16319))
+
+    In previous versions of Ruff, you could specify your Python version with:
+
+    - The `target-version` option in a `ruff.toml` file or the `[tool.ruff]` section of a pyproject.toml file.
+    - The `project.requires-python` field in a `pyproject.toml` file with a `[tool.ruff]` section.
+
+    These options worked well in most cases, and are still recommended for fine control of the Python version. However, because of the way Ruff discovers config files, `pyproject.toml` files without a `[tool.ruff]` section would be ignored, including the `requires-python` setting. Ruff would then use the default Python version (3.9 as of this writing) instead, which is surprising when you've attempted to request another version.
+
+    In v0.10, config discovery has been updated to address this issue:
+
+    - If Ruff finds a `ruff.toml` file without a `target-version`, it will check
+        for a `pyproject.toml` file in the same directory and respect its
+        `requires-python` version, even if it does not contain a `[tool.ruff]`
+        section.
+    - If Ruff finds a user-level configuration, the `requires-python` field of the closest `pyproject.toml` in a parent directory will take precedence.
+    - If there is no config file (`ruff.toml`or `pyproject.toml` with a
+        `[tool.ruff]` section) in the directory of the file being checked, Ruff will
+        search for the closest `pyproject.toml` in the parent directories and use its
+        `requires-python` setting.
+
+## 0.10.0
+
+- **Changes to how the Python version is inferred when a `target-version` is not specified** ([#16319](https://github.com/astral-sh/ruff/pull/16319))
+
+    Because of a mistake in the release process, the `requires-python` inference changes are not included in this release and instead shipped as part of 0.11.0.
+    You can find a description of this change in the 0.11.0 section.
+
+- **Updated `TYPE_CHECKING` behavior** ([#16669](https://github.com/astral-sh/ruff/pull/16669))
+
+    Previously, Ruff only recognized typechecking blocks that tested the `typing.TYPE_CHECKING` symbol. Now, Ruff recognizes any local variable named `TYPE_CHECKING`. This release also removes support for the legacy `if 0:` and `if False:` typechecking checks. Use a local `TYPE_CHECKING` variable instead.
+
+- **More robust noqa parsing** ([#16483](https://github.com/astral-sh/ruff/pull/16483))
+
+    The syntax for both file-level and in-line suppression comments has been unified and made more robust to certain errors. In most cases, this will result in more suppression comments being read by Ruff, but there are a few instances where previously read comments will now log an error to the user instead. Please refer to the documentation on [_Error suppression_](https://docs.astral.sh/ruff/linter/#error-suppression) for the full specification.
+
+- **Avoid unnecessary parentheses around with statements with a single context manager and a trailing comment** ([#14005](https://github.com/astral-sh/ruff/pull/14005))
+
+    This change fixes a bug in the formatter where it introduced unnecessary parentheses around with statements with a single context manager and a trailing comment. This change may result in a change in formatting for some users.
+
+- **Bump alpine default tag to 3.21 for derived Docker images** ([#16456](https://github.com/astral-sh/ruff/pull/16456))
+
+    Alpine 3.21 was released in Dec 2024 and is used in the official Alpine-based Python images. Now the ruff:alpine image will use 3.21 instead of 3.20 and ruff:alpine3.20 will no longer be updated.
+
+- **\[`unsafe-markup-use`\]: `RUF035` has been recoded to `S704`** ([#15957](https://github.com/astral-sh/ruff/pull/15957))
+
 ## 0.9.0
 
 Ruff now formats your code according to the 2025 style guide. As a result, your code might now get formatted differently. See the [changelog](./CHANGELOG.md#090) for a detailed list of changes.

CHANGELOG.md

@@ -1,5 +1,181 @@
 # Changelog
 
+## 0.11.2
+
+### Preview features
+
+- [syntax-errors] Fix false-positive syntax errors emitted for annotations on variadic parameters before Python 3.11 ([#16878](https://github.com/astral-sh/ruff/pull/16878))
+
+## 0.11.1
+
+### Preview features
+
+- \[`airflow`\] Add `chain`, `chain_linear` and `cross_downstream` for `AIR302` ([#16647](https://github.com/astral-sh/ruff/pull/16647))
+- [syntax-errors] Improve error message and range for pre-PEP-614 decorator syntax errors ([#16581](https://github.com/astral-sh/ruff/pull/16581))
+- [syntax-errors] PEP 701 f-strings before Python 3.12 ([#16543](https://github.com/astral-sh/ruff/pull/16543))
+- [syntax-errors] Parenthesized context managers before Python 3.9 ([#16523](https://github.com/astral-sh/ruff/pull/16523))
+- [syntax-errors] Star annotations before Python 3.11 ([#16545](https://github.com/astral-sh/ruff/pull/16545))
+- [syntax-errors] Star expression in index before Python 3.11 ([#16544](https://github.com/astral-sh/ruff/pull/16544))
+- [syntax-errors] Unparenthesized assignment expressions in sets and indexes ([#16404](https://github.com/astral-sh/ruff/pull/16404))
+
+### Bug fixes
+
+- Server: Allow `FixAll` action in presence of version-specific syntax errors ([#16848](https://github.com/astral-sh/ruff/pull/16848))
+- \[`flake8-bandit`\] Allow raw strings in `suspicious-mark-safe-usage` (`S308`) #16702 ([#16770](https://github.com/astral-sh/ruff/pull/16770))
+- \[`refurb`\] Avoid panicking `unwrap` in `verbose-decimal-constructor` (`FURB157`) ([#16777](https://github.com/astral-sh/ruff/pull/16777))
+- \[`refurb`\] Fix starred expressions fix (`FURB161`) ([#16550](https://github.com/astral-sh/ruff/pull/16550))
+- Fix `--statistics` reporting for unsafe fixes ([#16756](https://github.com/astral-sh/ruff/pull/16756))
+
+### Rule changes
+
+- \[`flake8-executables`\] Allow `uv run` in shebang line for `shebang-missing-python` (`EXE003`) ([#16849](https://github.com/astral-sh/ruff/pull/16849),[#16855](https://github.com/astral-sh/ruff/pull/16855))
+
+### CLI
+
+- Add `--exit-non-zero-on-format` ([#16009](https://github.com/astral-sh/ruff/pull/16009))
+
+### Documentation
+
+- Update Ruff tutorial to avoid non-existent fix in `__init__.py` ([#16818](https://github.com/astral-sh/ruff/pull/16818))
+- \[`flake8-gettext`\] Swap `format-` and `printf-in-get-text-func-call` examples (`INT002`, `INT003`) ([#16769](https://github.com/astral-sh/ruff/pull/16769))
+
+## 0.11.0
+
+This is a follow-up to release 0.10.0. Because of a mistake in the release process, the `requires-python` inference changes were not included in that release. Ruff 0.11.0 now includes this change as well as the stabilization of the preview behavior for `PGH004`.
+
+### Breaking changes
+
+- **Changes to how the Python version is inferred when a `target-version` is not specified** ([#16319](https://github.com/astral-sh/ruff/pull/16319))
+
+    In previous versions of Ruff, you could specify your Python version with:
+
+    - The `target-version` option in a `ruff.toml` file or the `[tool.ruff]` section of a pyproject.toml file.
+    - The `project.requires-python` field in a `pyproject.toml` file with a `[tool.ruff]` section.
+
+    These options worked well in most cases, and are still recommended for fine control of the Python version. However, because of the way Ruff discovers config files, `pyproject.toml` files without a `[tool.ruff]` section would be ignored, including the `requires-python` setting. Ruff would then use the default Python version (3.9 as of this writing) instead, which is surprising when you've attempted to request another version.
+
+    In v0.10, config discovery has been updated to address this issue:
+
+    - If Ruff finds a `ruff.toml` file without a `target-version`, it will check
+        for a `pyproject.toml` file in the same directory and respect its
+        `requires-python` version, even if it does not contain a `[tool.ruff]`
+        section.
+    - If Ruff finds a user-level configuration, the `requires-python` field of the closest `pyproject.toml` in a parent directory will take precedence.
+    - If there is no config file (`ruff.toml`or `pyproject.toml` with a
+        `[tool.ruff]` section) in the directory of the file being checked, Ruff will
+        search for the closest `pyproject.toml` in the parent directories and use its
+        `requires-python` setting.
+
+### Stabilization
+
+The following behaviors have been stabilized:
+
+- [`blanket-noqa`](https://docs.astral.sh/ruff/rules/blanket-noqa/) (`PGH004`): Also detect blanked file-level noqa comments (and not just line level comments).
+
+### Preview features
+
+- [syntax-errors] Tuple unpacking in `for` statement iterator clause before Python 3.9 ([#16558](https://github.com/astral-sh/ruff/pull/16558))
+
+## 0.10.0
+
+Check out the [blog post](https://astral.sh/blog/ruff-v0.10.0) for a migration guide and overview of the changes!
+
+### Breaking changes
+
+See also, the "Remapped rules" section which may result in disabled rules.
+
+- **Changes to how the Python version is inferred when a `target-version` is not specified** ([#16319](https://github.com/astral-sh/ruff/pull/16319))
+
+    Because of a mistake in the release process, the `requires-python` inference changes are not included in this release and instead shipped as part of 0.11.0.
+    You can find a description of this change in the 0.11.0 section.
+
+- **Updated `TYPE_CHECKING` behavior** ([#16669](https://github.com/astral-sh/ruff/pull/16669))
+
+    Previously, Ruff only recognized typechecking blocks that tested the `typing.TYPE_CHECKING` symbol. Now, Ruff recognizes any local variable named `TYPE_CHECKING`. This release also removes support for the legacy `if 0:` and `if False:` typechecking checks. Use a local `TYPE_CHECKING` variable instead.
+
+- **More robust noqa parsing** ([#16483](https://github.com/astral-sh/ruff/pull/16483))
+
+    The syntax for both file-level and in-line suppression comments has been unified and made more robust to certain errors. In most cases, this will result in more suppression comments being read by Ruff, but there are a few instances where previously read comments will now log an error to the user instead. Please refer to the documentation on [*Error suppression*](https://docs.astral.sh/ruff/linter/#error-suppression) for the full specification.
+
+- **Avoid unnecessary parentheses around with statements with a single context manager and a trailing comment** ([#14005](https://github.com/astral-sh/ruff/pull/14005))
+
+    This change fixes a bug in the formatter where it introduced unnecessary parentheses around with statements with a single context manager and a trailing comment. This change may result in a change in formatting for some users.
+
+- **Bump alpine default tag to 3.21 for derived Docker images** ([#16456](https://github.com/astral-sh/ruff/pull/16456))
+
+    Alpine 3.21 was released in Dec 2024 and is used in the official Alpine-based Python images. Now the ruff:alpine image will use 3.21 instead of 3.20 and ruff:alpine3.20 will no longer be updated.
+
+### Deprecated Rules
+
+The following rules have been deprecated:
+
+- [`non-pep604-isinstance`](https://docs.astral.sh/ruff/rules/non-pep604-isinstance/) (`UP038`)
+- [`suspicious-xmle-tree-usage`](https://docs.astral.sh/ruff/rules/suspicious-xmle-tree-usage/) (`S320`)
+
+### Remapped rules
+
+The following rules have been remapped to new rule codes:
+
+- \[`unsafe-markup-use`\]: `RUF035` to `S704`
+
+### Stabilization
+
+The following rules have been stabilized and are no longer in preview:
+
+- [`batched-without-explicit-strict`](https://docs.astral.sh/ruff/rules/batched-without-explicit-strict) (`B911`)
+- [`unnecessary-dict-comprehension-for-iterable`](https://docs.astral.sh/ruff/rules/unnecessary-dict-comprehension-for-iterable) (`C420`)
+- [`datetime-min-max`](https://docs.astral.sh/ruff/rules/datetime-min-max) (`DTZ901`)
+- [`fast-api-unused-path-parameter`](https://docs.astral.sh/ruff/rules/fast-api-unused-path-parameter) (`FAST003`)
+- [`root-logger-call`](https://docs.astral.sh/ruff/rules/root-logger-call) (`LOG015`)
+- [`len-test`](https://docs.astral.sh/ruff/rules/len-test) (`PLC1802`)
+- [`shallow-copy-environ`](https://docs.astral.sh/ruff/rules/shallow-copy-environ) (`PLW1507`)
+- [`os-listdir`](https://docs.astral.sh/ruff/rules/os-listdir) (`PTH208`)
+- [`invalid-pathlib-with-suffix`](https://docs.astral.sh/ruff/rules/invalid-pathlib-with-suffix) (`PTH210`)
+- [`invalid-assert-message-literal-argument`](https://docs.astral.sh/ruff/rules/invalid-assert-message-literal-argument) (`RUF040`)
+- [`unnecessary-nested-literal`](https://docs.astral.sh/ruff/rules/unnecessary-nested-literal) (`RUF041`)
+- [`unnecessary-cast-to-int`](https://docs.astral.sh/ruff/rules/unnecessary-cast-to-int) (`RUF046`)
+- [`map-int-version-parsing`](https://docs.astral.sh/ruff/rules/map-int-version-parsing) (`RUF048`)
+- [`if-key-in-dict-del`](https://docs.astral.sh/ruff/rules/if-key-in-dict-del) (`RUF051`)
+- [`unsafe-markup-use`](https://docs.astral.sh/ruff/rules/unsafe-markup-use) (`S704`). This rule has also been renamed from `RUF035`.
+- [`split-static-string`](https://docs.astral.sh/ruff/rules/split-static-string) (`SIM905`)
+- [`runtime-cast-value`](https://docs.astral.sh/ruff/rules/runtime-cast-value) (`TC006`)
+- [`unquoted-type-alias`](https://docs.astral.sh/ruff/rules/unquoted-type-alias) (`TC007`)
+- [`non-pep646-unpack`](https://docs.astral.sh/ruff/rules/non-pep646-unpack) (`UP044`)
+
+The following behaviors have been stabilized:
+
+- [`bad-staticmethod-argument`](https://docs.astral.sh/ruff/rules/bad-staticmethod-argument/) (`PLW0211`) [`invalid-first-argument-name-for-class-method`](https://docs.astral.sh/ruff/rules/invalid-first-argument-name-for-class-method/) (`N804`): `__new__` methods are now no longer flagged by `invalid-first-argument-name-for-class-method` (`N804`) but instead by `bad-staticmethod-argument` (`PLW0211`)
+- [`bad-str-strip-call`](https://docs.astral.sh/ruff/rules/bad-str-strip-call/) (`PLE1310`): The rule now applies to objects which are known to have type `str` or `bytes`.
+- [`custom-type-var-for-self`](https://docs.astral.sh/ruff/rules/custom-type-var-for-self/) (`PYI019`): More accurate detection of custom `TypeVars` replaceable by `Self`. The range of the diagnostic is now the full function header rather than just the return annotation.
+- [`invalid-argument-name`](https://docs.astral.sh/ruff/rules/invalid-argument-name/) (`N803`): Ignore argument names of functions decorated with `typing.override`
+- [`invalid-envvar-default`](https://docs.astral.sh/ruff/rules/invalid-envvar-default/) (`PLW1508`): Detect default value arguments to `os.environ.get` with invalid type.
+- [`pytest-raises-with-multiple-statements`](https://docs.astral.sh/ruff/rules/pytest-raises-with-multiple-statements/) (`PT012`) [`pytest-warns-with-multiple-statements`](https://docs.astral.sh/ruff/rules/pytest-warns-with-multiple-statements/) (`PT031`): Allow `for` statements with an empty body in `pytest.raises` and `pytest.warns` `with` statements.
+- [`redundant-open-modes`](https://docs.astral.sh/ruff/rules/redundant-open-modes/) (`UP015`): The diagnostic range is now the range of the redundant mode argument where it previously was the range of the entire open call. You may have to replace your `noqa` comments when suppressing `UP015`.
+- [`stdlib-module-shadowing`](https://docs.astral.sh/ruff/rules/stdlib-module-shadowing/) (`A005`): Changes the default value of `lint.flake8-builtins.strict-checking` from `true` to `false`.
+- [`type-none-comparison`](https://docs.astral.sh/ruff/rules/type-none-comparison/) (`FURB169`): Now also recognizes `type(expr) is type(None)` comparisons where `expr` isn't a name expression.
+
+The following fixes or improvements to fixes have been stabilized:
+
+- [`repeated-equality-comparison`](https://docs.astral.sh/ruff/rules/repeated-equality-comparison/) (`PLR1714`) ([#16685](https://github.com/astral-sh/ruff/pull/16685))
+- [`needless-bool`](https://docs.astral.sh/ruff/rules/needless-bool/) (`SIM103`) ([#16684](https://github.com/astral-sh/ruff/pull/16684))
+- [`unused-private-type-var`](https://docs.astral.sh/ruff/rules/unused-private-type-var/) (`PYI018`) ([#16682](https://github.com/astral-sh/ruff/pull/16682))
+
+### Server
+
+- Remove logging output for `ruff.printDebugInformation` ([#16617](https://github.com/astral-sh/ruff/pull/16617))
+
+### Configuration
+
+- \[`flake8-builtins`\] Deprecate the `builtins-` prefixed options in favor of the unprefixed options (e.g. `builtins-allowed-modules` is now deprecated in favor of `allowed-modules`) ([#16092](https://github.com/astral-sh/ruff/pull/16092))
+
+### Bug fixes
+
+- [flake8-bandit] Fix mixed-case hash algorithm names (S324) ([#16552](https://github.com/astral-sh/ruff/pull/16552))
+
+### CLI
+
+- [ruff] Fix `last_tag`/`commits_since_last_tag` for `version` command ([#16686](https://github.com/astral-sh/ruff/pull/16686))
+
 ## 0.9.10
 
 ### Preview features

Cargo.lock

@@ -46,9 +46,13 @@ checksum = "4b46cbb362ab8752921c97e041f5e366ee6297bd428a31275b9fcf1e380f7299"
 
 [[package]]
 name = "annotate-snippets"
-version = "0.6.1"
+version = "0.11.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c7021ce4924a3f25f802b2cccd1af585e39ea1a363a1aa2e72afe54b67a3a7a7"
+checksum = "710e8eae58854cdc1790fcb56cca04d712a17be849eeb81da2a724bf4bae2bc4"
+dependencies = [
+ "anstyle",
+ "unicode-width 0.2.0",
+]
 
 [[package]]
 name = "anstream"
@@ -268,9 +272,9 @@ dependencies = [
 
 [[package]]
 name = "cc"
-version = "1.2.11"
+version = "1.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e4730490333d58093109dc02c23174c3f4d490998c3fed3cc8e82d57afedb9cf"
+checksum = "be714c154be609ec7f5dad223a33bf1482fff90472de28f7362806e6d4832b8c"
 dependencies = [
  "jobserver",
  "libc",
@@ -289,15 +293,6 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
 
-[[package]]
-name = "chic"
-version = "1.2.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a5b5db619f3556839cb2223ae86ff3f9a09da2c5013be42bc9af08c9589bf70c"
-dependencies = [
- "annotate-snippets",
-]
-
 [[package]]
 name = "chrono"
 version = "0.4.40"
@@ -339,9 +334,9 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.5.31"
+version = "4.5.32"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "027bb0d98429ae334a8698531da7077bdf906419543a35a55c2cb1b66437d767"
+checksum = "6088f3ae8c3608d19260cd7445411865a485688711b78b5be70d78cd96136f83"
 dependencies = [
  "clap_builder",
  "clap_derive",
@@ -349,9 +344,9 @@ dependencies = [
 
 [[package]]
 name = "clap_builder"
-version = "4.5.31"
+version = "4.5.32"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5589e0cba072e0f3d23791efac0fd8627b49c829c196a492e88168e6a669d863"
+checksum = "22a7ef7f676155edfb82daa97f99441f3ebf4a58d5e32f295a56259f1b6facc8"
 dependencies = [
  "anstream",
  "anstyle",
@@ -362,9 +357,9 @@ dependencies = [
 
 [[package]]
 name = "clap_complete"
-version = "4.5.44"
+version = "4.5.46"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "375f9d8255adeeedd51053574fd8d4ba875ea5fa558e86617b07f09f1680c8b6"
+checksum = "f5c5508ea23c5366f77e53f5a0070e5a84e51687ec3ef9e0464c86dc8d13ce98"
 dependencies = [
  "clap",
 ]
@@ -392,9 +387,9 @@ dependencies = [
 
 [[package]]
 name = "clap_derive"
-version = "4.5.28"
+version = "4.5.32"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bf4ced95c6f4a675af3da73304b9ac4ed991640c36374e4b46795c49e17cf1ed"
+checksum = "09176aae279615badda0765c0c0b3f6ed53f4709118af73cf4655d85d1530cd7"
 dependencies = [
  "heck",
  "proc-macro2",
@@ -423,9 +418,9 @@ dependencies = [
 
 [[package]]
 name = "codspeed"
-version = "2.8.1"
+version = "2.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "de4b67ff8985f3993f06167d71cf4aec178b0a1580f91a987170c59d60021103"
+checksum = "60e744216bfa9add3b1f2505587cbbb837923232ed10963609f4a6e3cbd99c3e"
 dependencies = [
  "colored 2.2.0",
  "libc",
@@ -436,13 +431,38 @@ dependencies = [
 
 [[package]]
 name = "codspeed-criterion-compat"
-version = "2.8.1"
+version = "2.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "68403d768ed1def18a87e2306676781314448393ecf0d3057c4527cabf524a3d"
+checksum = "d5926ca63222a35b9a2299adcaafecf596efe20a9a2048e4a81cb2fc3463b4a8"
 dependencies = [
  "codspeed",
+ "codspeed-criterion-compat-walltime",
  "colored 2.2.0",
- "criterion",
+]
+
+[[package]]
+name = "codspeed-criterion-compat-walltime"
+version = "2.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dbae4da05076cbc673e242400ac8f4353bdb686e48020edc6e36a5c36ae0878e"
+dependencies = [
+ "anes",
+ "cast",
+ "ciborium",
+ "clap",
+ "codspeed",
+ "criterion-plot",
+ "is-terminal",
+ "itertools 0.10.5",
+ "num-traits",
+ "once_cell",
+ "oorandom",
+ "regex",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "tinytemplate",
+ "walkdir",
 ]
 
 [[package]]
@@ -458,7 +478,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "117725a109d387c937a1533ce01b450cbde6b88abceea8473c4d7a85853cda3c"
 dependencies = [
  "lazy_static",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -467,7 +487,7 @@ version = "3.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fde0e0ec90c9dfb3b4b1a0891a7dcd0e2bffde2f7efed5fe7c9bb00e5bfb915e"
 dependencies = [
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -475,6 +495,20 @@ name = "compact_str"
 version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3b79c4069c6cad78e2e0cdfcbd26275770669fb39fd308a752dc110e83b9af32"
+dependencies = [
+ "castaway",
+ "cfg-if",
+ "itoa",
+ "rustversion",
+ "ryu",
+ "static_assertions",
+]
+
+[[package]]
+name = "compact_str"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3fdb1325a1cece981e8a296ab8f0f9b63ae357bd0784a9faaf548cc7b480707a"
 dependencies = [
  "castaway",
  "cfg-if",
@@ -487,9 +521,9 @@ dependencies = [
 
 [[package]]
 name = "console"
-version = "0.15.10"
+version = "0.15.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ea3c6ecd8059b57859df5c69830340ed3c41d30e3da0c1cbed90a96ac853041b"
+checksum = "054ccb5b10f9f2cbf51eb355ca1d05c2d279ce1804688d0db74b4733a5aeafd8"
 dependencies = [
  "encode_unicode",
  "libc",
@@ -826,15 +860,15 @@ checksum = "92773504d58c093f6de2459af4af33faa518c13451eb8f2b5698ed3d36e7c813"
 
 [[package]]
 name = "dyn-clone"
-version = "1.0.18"
+version = "1.0.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "feeef44e73baff3a26d371801df019877a9866a8c493d315ab00177843314f35"
+checksum = "1c7a8fb8a9fbf66c1f703fe16184d10ca0ee9d23be5b4436400408ba54a95005"
 
 [[package]]
 name = "either"
-version = "1.13.0"
+version = "1.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
+checksum = "48c757948c5ede0e46177b7add2e67155f70e33c07fea8284df6576da70b3719"
 
 [[package]]
 name = "encode_unicode"
@@ -860,22 +894,22 @@ checksum = "c7f84e12ccf0a7ddc17a6c41c93326024c42920d7ee630d04950e6926645c0fe"
 
 [[package]]
 name = "env_logger"
-version = "0.11.6"
+version = "0.11.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dcaee3d8e3cfc3fd92428d477bc97fc29ec8716d180c0d74c643bb26166660e0"
+checksum = "c3716d7a920fb4fac5d84e9d4bce8ceb321e9414b4409da61b07b75c1e3d0697"
 dependencies = [
  "anstream",
  "anstyle",
  "env_filter",
- "humantime",
+ "jiff",
  "log",
 ]
 
 [[package]]
 name = "equivalent"
-version = "1.0.1"
+version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
+checksum = "877a4ace8713b0bcf2a4e7eec82529c029f1d0619886d18145fea96c3ffe5c0f"
 
 [[package]]
 name = "errno"
@@ -884,7 +918,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "33d852cb9b869c2a9b3df2f71a3074817f01e1844f839a144f5fcef059a4eb5d"
 dependencies = [
  "libc",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -907,13 +941,13 @@ dependencies = [
 
 [[package]]
 name = "etcetera"
-version = "0.8.0"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "136d1b5283a1ab77bd9257427ffd09d8667ced0570b6f938942bc7568ed5b943"
+checksum = "26c7b13d0780cb82722fd59f6f57f925e143427e4a75313a6c77243bf5326ae6"
 dependencies = [
  "cfg-if",
  "home",
- "windows-sys 0.48.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -945,9 +979,9 @@ dependencies = [
 
 [[package]]
 name = "flate2"
-version = "1.0.35"
+version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c936bfdafb507ebbf50b8074c54fa31c5be9a1e7e5f467dd659697041407d07c"
+checksum = "11faaf5a5236997af9848be0bef4db95824b1d534ebc64d0f0c6cf3e67bd38dc"
 dependencies = [
  "crc32fast",
  "miniz_oxide",
@@ -961,9 +995,9 @@ checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
 [[package]]
 name = "foldhash"
-version = "0.1.4"
+version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a0d2fde1f7b3d48b8395d5f2de76c18a528bd6a9cdde438df747bfcba3e05d6f"
+checksum = "d9c4f5dac5e15c24eb999c26181a6ca40b39fe946cbe4c263c7209467bc83af2"
 
 [[package]]
 name = "form_urlencoded"
@@ -1081,9 +1115,9 @@ dependencies = [
 
 [[package]]
 name = "half"
-version = "2.4.1"
+version = "2.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6dd08c532ae367adf81c312a4580bc67f1d0fe8bc9c460520283f4c0ff277888"
+checksum = "7db2ff139bba50379da6aa0766b52fdcb62cb5b263009b09ed58ba604e14bbd1"
 dependencies = [
  "cfg-if",
  "crunchy",
@@ -1129,17 +1163,17 @@ checksum = "d231dfb89cfffdbc30e7fc41579ed6066ad03abda9e567ccafae602b97ec5024"
 
 [[package]]
 name = "hermit-abi"
-version = "0.4.0"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fbf6a919d6cf397374f7dfeeea91d974c7c0a7221d0d0f4f20d859d329e53fcc"
+checksum = "fbd780fe5cc30f81464441920d82ac8740e2e46b29a6fad543ddd075229ce37e"
 
 [[package]]
 name = "home"
-version = "0.5.9"
+version = "0.5.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e3d1354bf6b7235cb4a0576c2619fd4ed18183f689b12b006a0ee7329eeff9a5"
+checksum = "589533453244b0995c858700322199b2becb13b627df2851f64a2775d024abcf"
 dependencies = [
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -1151,12 +1185,6 @@ dependencies = [
  "utf8-width",
 ]
 
-[[package]]
-name = "humantime"
-version = "2.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9a3a5bfb195931eeb336b2a7b4d761daec841b97f947d34394601737a7bba5e4"
-
 [[package]]
 name = "iana-time-zone"
 version = "0.1.61"
@@ -1362,9 +1390,9 @@ dependencies = [
 
 [[package]]
 name = "indexmap"
-version = "2.7.1"
+version = "2.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8c9c992b02b5b4c94ea26e32fe5bccb7aa7d9f390ab5c1221ff895bc7ea8b652"
+checksum = "3954d50fe15b02142bf25d3b8bdadb634ec3948f103d04ffe3031bc8fe9d7058"
 dependencies = [
  "equivalent",
  "hashbrown 0.15.2",
@@ -1465,13 +1493,13 @@ dependencies = [
 
 [[package]]
 name = "is-terminal"
-version = "0.4.15"
+version = "0.4.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e19b23d53f35ce9f56aebc7d1bb4e6ac1e9c0db7ac85c8d1760c04379edced37"
+checksum = "e04d7f318608d35d4b61ddd75cbdaee86b023ebe2bd5a66ee0915f0bf93095a9"
 dependencies = [
- "hermit-abi 0.4.0",
+ "hermit-abi 0.5.0",
  "libc",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -1519,9 +1547,33 @@ dependencies = [
 
 [[package]]
 name = "itoa"
-version = "1.0.14"
+version = "1.0.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d75a2a4b1b190afb6f5425f10f6a8f959d2ea0b9c2b1d79553551850539e4674"
+checksum = "4a5f13b858c8d314ee3e8f639011f7ccefe71f97f96e50151fb991f267928e2c"
+
+[[package]]
+name = "jiff"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d699bc6dfc879fb1bf9bdff0d4c56f0884fc6f0d0eb0fba397a6d00cd9a6b85e"
+dependencies = [
+ "jiff-static",
+ "log",
+ "portable-atomic",
+ "portable-atomic-util",
+ "serde",
+]
+
+[[package]]
+name = "jiff-static"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d16e75759ee0aa64c57a56acbf43916987b20c77373cb7e808979e02b93c9f9"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.100",
+]
 
 [[package]]
 name = "jobserver"
@@ -1576,17 +1628,17 @@ checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
 
 [[package]]
 name = "libc"
-version = "0.2.170"
+version = "0.2.171"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "875b3680cb2f8f71bdcf9a30f38d48282f5d3c95cbf9b3fa57269bb5d5c06828"
+checksum = "c19937216e9d3aa9956d9bb8dfc0b0c8beb6058fc4f7a4dc4d850edf86a237d6"
 
 [[package]]
 name = "libcst"
-version = "1.6.0"
+version = "1.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "649801a698a649791541a3125d396d5db065ed7cea53faca3652b0179394922a"
+checksum = "ad9e315e3f679e61b9095ffd5e509de78b8a4ea3bba9d772f6fb243209f808d4"
 dependencies = [
- "chic",
+ "annotate-snippets",
  "libcst_derive",
  "memchr",
  "paste",
@@ -1597,9 +1649,9 @@ dependencies = [
 
 [[package]]
 name = "libcst_derive"
-version = "1.6.0"
+version = "1.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3bf66548c351bcaed792ef3e2b430cc840fbde504e09da6b29ed114ca60dcd4b"
+checksum = "bfa96ed35d0dccc67cf7ba49350cb86de3dcb1d072a7ab28f99117f19d874953"
 dependencies = [
  "quote",
  "syn 2.0.100",
@@ -1651,10 +1703,16 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d26c52dbd32dccf2d10cac7725f8eae5296885fb5703b261f7d0a0739ec807ab"
 
 [[package]]
-name = "litemap"
-version = "0.7.4"
+name = "linux-raw-sys"
+version = "0.9.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4ee93343901ab17bd981295f2cf0026d4ad018c7c31ba84549a4ddbb47a45104"
+checksum = "fe7db12097d22ec582439daf8618b8fdd1a7bef6270e9af3b1ebcd30893cf413"
+
+[[package]]
+name = "litemap"
+version = "0.7.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "23fb14cb19457329c82206317a5663005a4d404783dc74f4252769b0d5f42856"
 
 [[package]]
 name = "lock_api"
@@ -1764,9 +1822,9 @@ checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
 
 [[package]]
 name = "miniz_oxide"
-version = "0.8.3"
+version = "0.8.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b8402cab7aefae129c6977bb0ff1b8fd9a04eb5b51efc50a70bea51cda0c7924"
+checksum = "8e3e04debbb59698c15bacbb6d93584a8c0ca9cc3213cb423d31f760d8843ce5"
 dependencies = [
  "adler2",
 ]
@@ -1897,15 +1955,15 @@ checksum = "830b246a0e5f20af87141b25c173cd1b609bd7779a4617d6ec582abaf90870f3"
 
 [[package]]
 name = "once_cell"
-version = "1.20.2"
+version = "1.21.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1261fe7e33c73b354eab43b1273a57c8f967d0391e80353e51f764ac02cf6775"
+checksum = "d75b0bedcc4fe52caa0e03d9f1151a323e4aa5e2d78ba3580400cd3c9e2bc4bc"
 
 [[package]]
 name = "oorandom"
-version = "11.1.4"
+version = "11.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b410bbe7e14ab526a0e86877eb47c6996a2bd7746f027ba551028c925390e4e9"
+checksum = "d6790f58c7ff633d8771f42965289203411a5e5c68388703c06e14f24770b41e"
 
 [[package]]
 name = "option-ext"
@@ -1915,9 +1973,9 @@ checksum = "04744f49eae99ab78e0d5c0b603ab218f515ea8cfe5a456d7629ad883a3b6e7d"
 
 [[package]]
 name = "ordermap"
-version = "0.5.5"
+version = "0.5.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c55fdf45a2b1e929e3656d404395767e05c98b6ebd8157eb31e370077d545160"
+checksum = "6e98f974336ceffd5b1b1f4fcbb89a23c8dcd334adc4b8612f11b7fa99944535"
 dependencies = [
  "indexmap",
 ]
@@ -1934,9 +1992,9 @@ dependencies = [
 
 [[package]]
 name = "os_str_bytes"
-version = "7.0.0"
+version = "7.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7ac44c994af577c799b1b4bd80dc214701e349873ad894d6cdf96f4f7526e0b9"
+checksum = "c86e2db86dd008b4c88c77a9bb83d9286bf77204e255bb3fda3b2eebcae66b62"
 dependencies = [
  "memchr",
 ]
@@ -2008,9 +2066,9 @@ checksum = "df94ce210e5bc13cb6651479fa48d14f601d9858cfe0467f43ae157023b938d3"
 
 [[package]]
 name = "peg"
-version = "0.8.4"
+version = "0.8.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "295283b02df346d1ef66052a757869b2876ac29a6bb0ac3f5f7cd44aebe40e8f"
+checksum = "9928cfca101b36ec5163e70049ee5368a8a1c3c6efc9ca9c5f9cc2f816152477"
 dependencies = [
  "peg-macros",
  "peg-runtime",
@@ -2018,9 +2076,9 @@ dependencies = [
 
 [[package]]
 name = "peg-macros"
-version = "0.8.4"
+version = "0.8.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bdad6a1d9cf116a059582ce415d5f5566aabcd4008646779dab7fdc2a9a9d426"
+checksum = "6298ab04c202fa5b5d52ba03269fb7b74550b150323038878fe6c372d8280f71"
 dependencies = [
  "peg-runtime",
  "proc-macro2",
@@ -2029,9 +2087,9 @@ dependencies = [
 
 [[package]]
 name = "peg-runtime"
-version = "0.8.3"
+version = "0.8.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e3aeb8f54c078314c2065ee649a7241f46b9d8e418e1a9581ba0546657d7aa3a"
+checksum = "132dca9b868d927b35b5dd728167b2dee150eb1ad686008fc71ccb298b776fca"
 
 [[package]]
 name = "pep440_rs"
@@ -2159,18 +2217,18 @@ dependencies = [
 
 [[package]]
 name = "pin-project"
-version = "1.1.9"
+version = "1.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dfe2e71e1471fe07709406bf725f710b02927c9c54b2b5b2ec0e8087d97c327d"
+checksum = "677f1add503faace112b9f1373e43e9e054bfdd22ff1a63c1bc485eaec6a6a8a"
 dependencies = [
  "pin-project-internal",
 ]
 
 [[package]]
 name = "pin-project-internal"
-version = "1.1.9"
+version = "1.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f6e859e6e5bd50440ab63c47e3ebabc90f26251f7c73c3d3e837b74a1cc3fa67"
+checksum = "6e918e4ff8c4549eb882f14b3a4bc8c8bc93de829416eacf579f1207a8fbf861"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -2185,23 +2243,32 @@ checksum = "3b3cff922bd51709b605d9ead9aa71031d81447142d828eb4a6eba76fe619f9b"
 
 [[package]]
 name = "pkg-config"
-version = "0.3.31"
+version = "0.3.32"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "953ec861398dccce10c670dfeaf3ec4911ca479e9c02154b3a215178c5f566f2"
+checksum = "7edddbd0b52d732b21ad9a5fab5c704c14cd949e5e9a1ec5929a24fded1b904c"
 
 [[package]]
 name = "portable-atomic"
-version = "1.10.0"
+version = "1.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "280dc24453071f1b63954171985a0b0d30058d287960968b9b2aca264c8d4ee6"
+checksum = "350e9b48cbc6b0e028b0473b114454c6316e57336ee184ceab6e53f72c178b3e"
+
+[[package]]
+name = "portable-atomic-util"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d8a2f0d8d040d7848a709caf78912debcc3f33ee4b3cac47d73d1e1069e83507"
+dependencies = [
+ "portable-atomic",
+]
 
 [[package]]
 name = "ppv-lite86"
-version = "0.2.20"
+version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "77957b295656769bb8ad2b6a6b09d897d94f05c41b069aede1fcdaa675eaea04"
+checksum = "85eae3c4ed2f50dcfe72643da4befc30deadb458a9b590d720cde2f2b1e97da9"
 dependencies = [
- "zerocopy 0.7.35",
+ "zerocopy",
 ]
 
 [[package]]
@@ -2310,9 +2377,9 @@ dependencies = [
 
 [[package]]
 name = "quote"
-version = "1.0.39"
+version = "1.0.40"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c1f1914ce909e1658d9907913b4b91947430c7d9be598b15a1912935b8c04801"
+checksum = "1885c039570dc00dcb4ff087a89e185fd56bae234ddc7f056a945bf36467248d"
 dependencies = [
  "proc-macro2",
 ]
@@ -2335,8 +2402,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3779b94aeb87e8bd4e834cee3650289ee9e0d5677f976ecdb6d219e5f4f6cd94"
 dependencies = [
  "rand_chacha 0.9.0",
- "rand_core 0.9.0",
- "zerocopy 0.8.14",
+ "rand_core 0.9.3",
+ "zerocopy",
 ]
 
 [[package]]
@@ -2356,7 +2423,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d3022b5f1df60f26e1ffddd6c66e8aa15de382ae63b3a0c1bfc0e4d3e3f325cb"
 dependencies = [
  "ppv-lite86",
- "rand_core 0.9.0",
+ "rand_core 0.9.3",
 ]
 
 [[package]]
@@ -2370,12 +2437,11 @@ dependencies = [
 
 [[package]]
 name = "rand_core"
-version = "0.9.0"
+version = "0.9.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b08f3c9802962f7e1b25113931d94f43ed9725bebc59db9d0c3e9a23b67e15ff"
+checksum = "99d9a13982dcf210057a8a78572b2217b667c3beacbf3a0d8b454f6f82837d38"
 dependencies = [
  "getrandom 0.3.1",
- "zerocopy 0.8.14",
 ]
 
 [[package]]
@@ -2465,7 +2531,7 @@ dependencies = [
  "anyhow",
  "bitflags 2.9.0",
  "camino",
- "compact_str",
+ "compact_str 0.9.0",
  "countme",
  "dir-test",
  "drop_bomb",
@@ -2578,15 +2644,17 @@ dependencies = [
  "ruff_db",
  "ruff_notebook",
  "ruff_python_ast",
+ "ruff_source_file",
+ "ruff_text_size",
  "wasm-bindgen",
  "wasm-bindgen-test",
 ]
 
 [[package]]
 name = "redox_syscall"
-version = "0.5.8"
+version = "0.5.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "03a862b389f93e68874fbf580b9de08dd02facb9a788ebadaf4a3fd33cf58834"
+checksum = "0b8c0c260b63a8219631167be35e6a988e9554dbd323f8bd08439c8ed1302bd1"
 dependencies = [
  "bitflags 2.9.0",
 ]
@@ -2659,7 +2727,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.9.10"
+version = "0.11.2"
 dependencies = [
  "anyhow",
  "argfile",
@@ -2894,7 +2962,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_linter"
-version = "0.9.10"
+version = "0.11.2"
 dependencies = [
  "aho-corasick",
  "anyhow",
@@ -2989,7 +3057,7 @@ version = "0.0.0"
 dependencies = [
  "aho-corasick",
  "bitflags 2.9.0",
- "compact_str",
+ "compact_str 0.9.0",
  "is-macro",
  "itertools 0.14.0",
  "memchr",
@@ -3085,7 +3153,7 @@ dependencies = [
  "anyhow",
  "bitflags 2.9.0",
  "bstr",
- "compact_str",
+ "compact_str 0.9.0",
  "insta",
  "memchr",
  "ruff_annotate_snippets",
@@ -3192,6 +3260,7 @@ dependencies = [
  "thiserror 2.0.12",
  "toml",
  "tracing",
+ "tracing-log",
  "tracing-subscriber",
 ]
 
@@ -3216,7 +3285,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_wasm"
-version = "0.9.10"
+version = "0.11.2"
 dependencies = [
  "console_error_panic_hook",
  "console_log",
@@ -3309,35 +3378,49 @@ dependencies = [
  "bitflags 2.9.0",
  "errno",
  "libc",
- "linux-raw-sys",
- "windows-sys 0.52.0",
+ "linux-raw-sys 0.4.15",
+ "windows-sys 0.59.0",
+]
+
+[[package]]
+name = "rustix"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f7178faa4b75a30e269c71e61c353ce2748cf3d76f0c44c393f4e60abf49b825"
+dependencies = [
+ "bitflags 2.9.0",
+ "errno",
+ "libc",
+ "linux-raw-sys 0.9.3",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
 name = "rustversion"
-version = "1.0.19"
+version = "1.0.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f7c45b9784283f1b2e7fb61b42047c2fd678ef0960d4f6f1eba131594cc369d4"
+checksum = "eded382c5f5f786b989652c49544c4877d9f015cc22e145a5ea8ea66c2921cd2"
 
 [[package]]
 name = "ryu"
-version = "1.0.19"
+version = "1.0.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6ea1a2d0a644769cc99faa24c3ad26b379b786fe7c36fd3c546254801650e6dd"
+checksum = "28d3b2b1366ec20994f1fd18c3c594f05c5dd4bc44d8bb0c1c632c8d6829481f"
 
 [[package]]
 name = "salsa"
-version = "0.18.0"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=99be5d9917c3dd88e19735a82ef6bf39ba84bd7e#99be5d9917c3dd88e19735a82ef6bf39ba84bd7e"
+version = "0.19.0"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=d758691ba17ee1a60c5356ea90888d529e1782ad#d758691ba17ee1a60c5356ea90888d529e1782ad"
 dependencies = [
  "boxcar",
- "compact_str",
+ "compact_str 0.8.1",
  "crossbeam-queue",
  "dashmap 6.1.0",
  "hashbrown 0.15.2",
  "hashlink",
  "indexmap",
  "parking_lot",
+ "portable-atomic",
  "rayon",
  "rustc-hash 2.1.1",
  "salsa-macro-rules",
@@ -3348,13 +3431,13 @@ dependencies = [
 
 [[package]]
 name = "salsa-macro-rules"
-version = "0.1.0"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=99be5d9917c3dd88e19735a82ef6bf39ba84bd7e#99be5d9917c3dd88e19735a82ef6bf39ba84bd7e"
+version = "0.19.0"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=d758691ba17ee1a60c5356ea90888d529e1782ad#d758691ba17ee1a60c5356ea90888d529e1782ad"
 
 [[package]]
 name = "salsa-macros"
-version = "0.18.0"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=99be5d9917c3dd88e19735a82ef6bf39ba84bd7e#99be5d9917c3dd88e19735a82ef6bf39ba84bd7e"
+version = "0.19.0"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=d758691ba17ee1a60c5356ea90888d529e1782ad#d758691ba17ee1a60c5356ea90888d529e1782ad"
 dependencies = [
  "heck",
  "proc-macro2",
@@ -3470,9 +3553,9 @@ dependencies = [
 
 [[package]]
 name = "serde_repr"
-version = "0.1.19"
+version = "0.1.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6c64451ba24fc7a6a2d60fc75dd9c83c90903b19028d4eff35e88fc1e86564e9"
+checksum = "175ee3e80ae9982737ca543e96133087cbd9a485eecc3bc4de9c1a37b47ea59c"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -3686,16 +3769,15 @@ dependencies = [
 
 [[package]]
 name = "tempfile"
-version = "3.17.1"
+version = "3.19.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "22e5a0acb1f3f55f65cc4a866c361b2fb2a0ff6366785ae6fbb5f85df07ba230"
+checksum = "488960f40a3fd53d72c2a29a58722561dee8afdd175bd88e3db4677d7b2ba600"
 dependencies = [
- "cfg-if",
  "fastrand",
  "getrandom 0.3.1",
  "once_cell",
- "rustix",
- "windows-sys 0.52.0",
+ "rustix 1.0.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -3709,11 +3791,11 @@ dependencies = [
 
 [[package]]
 name = "terminal_size"
-version = "0.4.1"
+version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5352447f921fda68cf61b4101566c0bdb5104eff6804d0678e5227580ab6a4e9"
+checksum = "45c6481c4829e4cc63825e62c49186a34538b7b2750b73b266581ffb612fb5ed"
 dependencies = [
- "rustix",
+ "rustix 1.0.2",
  "windows-sys 0.59.0",
 ]
 
@@ -3869,9 +3951,9 @@ dependencies = [
 
 [[package]]
 name = "tinyvec"
-version = "1.8.1"
+version = "1.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "022db8904dfa342efe721985167e9fcd16c29b226db4397ed752a761cfce81e8"
+checksum = "09b3661f17e86524eccd4371ab0429194e0d7c008abb45f7a7495b1719463c71"
 dependencies = [
  "tinyvec_macros",
 ]
@@ -3905,9 +3987,9 @@ dependencies = [
 
 [[package]]
 name = "toml_edit"
-version = "0.22.23"
+version = "0.22.24"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "02a8b472d1a3d7c18e2d61a489aee3453fd9031c33e4f55bd533f4a7adca1bee"
+checksum = "17b4795ff5edd201c7cd6dca065ae59972ce77d1b80fa0a84d94950ece7d1474"
 dependencies = [
  "indexmap",
  "serde",
@@ -4033,9 +4115,9 @@ checksum = "6af6ae20167a9ece4bcb41af5b80f8a1f1df981f6391189ce00fd257af04126a"
 
 [[package]]
 name = "typenum"
-version = "1.17.0"
+version = "1.18.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "42ff0bf0c66b8238c6f3b578df37d0b7848e55df8577b3f74f92a69acceeb825"
+checksum = "1dccffe3ce07af9386bfd29e80c0ab1a8205a2fc34e4bcd40364df902cfa8f3f"
 
 [[package]]
 name = "ucd-trie"
@@ -4184,9 +4266,9 @@ checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
 
 [[package]]
 name = "uuid"
-version = "1.13.1"
+version = "1.16.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ced87ca4be083373936a67f8de945faa23b6b42384bd5b64434850802c6dccd0"
+checksum = "458f7a779bf54acc9f347480ac654f68407d3aab21269a6e3c9f922acd9e2da9"
 dependencies = [
  "getrandom 0.3.1",
  "js-sys",
@@ -4197,9 +4279,9 @@ dependencies = [
 
 [[package]]
 name = "uuid-macro-internal"
-version = "1.13.1"
+version = "1.16.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d28dd23acb5f2fa7bd2155ab70b960e770596b3bb6395119b40476c3655dfba4"
+checksum = "72dcd78c4f979627a754f5522cea6e6a25e55139056535fe6e69c506cd64a862"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -4271,9 +4353,9 @@ dependencies = [
 
 [[package]]
 name = "wait-timeout"
-version = "0.2.0"
+version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9f200f5b12eb75f8c1ed65abd4b2db8a6e1b138a20de009dacee265a2498f3f6"
+checksum = "09ac3b126d3914f9849036f826e054cbabdc8519970b8998ddaf3b5bd3c65f11"
 dependencies = [
  "libc",
 ]
@@ -4420,13 +4502,13 @@ dependencies = [
 
 [[package]]
 name = "which"
-version = "7.0.1"
+version = "7.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fb4a9e33648339dc1642b0e36e21b3385e6148e289226f657c809dee59df5028"
+checksum = "2774c861e1f072b3aadc02f8ba886c26ad6321567ecc294c935434cad06f1283"
 dependencies = [
  "either",
  "env_home",
- "rustix",
+ "rustix 0.38.44",
  "winsafe",
 ]
 
@@ -4461,7 +4543,7 @@ version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
 dependencies = [
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -4699,9 +4781,9 @@ checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
 
 [[package]]
 name = "winnow"
-version = "0.7.0"
+version = "0.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7e49d2d35d3fad69b39b94139037ecfb4f359f08958b9c11e7315ce770462419"
+checksum = "0e97b544156e9bebe1a0ffbc03484fc1ffe3100cbce3ffb17eac35f7cdd7ab36"
 dependencies = [
  "memchr",
 ]
@@ -4765,39 +4847,18 @@ dependencies = [
 
 [[package]]
 name = "zerocopy"
-version = "0.7.35"
+version = "0.8.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1b9b4fd18abc82b8136838da5d50bae7bdea537c574d8dc1a34ed098d6c166f0"
+checksum = "fd97444d05a4328b90e75e503a34bad781f14e28a823ad3557f0750df1ebcbc6"
 dependencies = [
- "byteorder",
- "zerocopy-derive 0.7.35",
-]
-
-[[package]]
-name = "zerocopy"
-version = "0.8.14"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a367f292d93d4eab890745e75a778da40909cab4d6ff8173693812f79c4a2468"
-dependencies = [
- "zerocopy-derive 0.8.14",
+ "zerocopy-derive",
 ]
 
 [[package]]
 name = "zerocopy-derive"
-version = "0.7.35"
+version = "0.8.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fa4f8080344d4671fb4e831a13ad1e68092748387dfc4f55e356242fae12ce3e"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.100",
-]
-
-[[package]]
-name = "zerocopy-derive"
-version = "0.8.14"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d3931cb58c62c13adec22e38686b559c86a30565e16ad6e8510a337cedc611e1"
+checksum = "6352c01d0edd5db859a63e2605f4ea3183ddbd15e2c4a9e7d32184df75e4f154"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -4806,18 +4867,18 @@ dependencies = [
 
 [[package]]
 name = "zerofrom"
-version = "0.1.5"
+version = "0.1.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cff3ee08c995dee1859d998dea82f7374f2826091dd9cd47def953cae446cd2e"
+checksum = "50cc42e0333e05660c3587f3bf9d0478688e15d870fab3346451ce7f8c9fbea5"
 dependencies = [
  "zerofrom-derive",
 ]
 
 [[package]]
 name = "zerofrom-derive"
-version = "0.1.5"
+version = "0.1.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "595eed982f7d355beb85837f651fa22e90b3c044842dc7f2c2842c086f295808"
+checksum = "d71e5d6e06ab090c67b5e44993ec16b72dcbaabc526db883a360057678b48502"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -4881,9 +4942,9 @@ dependencies = [
 
 [[package]]
 name = "zstd-sys"
-version = "2.0.13+zstd.1.5.6"
+version = "2.0.14+zstd.1.5.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "38ff0f21cfee8f97d94cef41359e0c89aa6113028ab0291aa8ca0038995a95aa"
+checksum = "8fb060d4926e4ac3a3ad15d864e99ceb5f343c6b34f5bd6d81ae6ed417311be5"
 dependencies = [
  "cc",
  "pkg-config",

Cargo.toml

@@ -63,7 +63,7 @@ colored = { version = "3.0.0" }
 console_error_panic_hook = { version = "0.1.7" }
 console_log = { version = "1.0.0" }
 countme = { version = "3.0.1" }
-compact_str = "0.8.0"
+compact_str = "0.9.0"
 criterion = { version = "0.5.1", default-features = false }
 crossbeam = { version = "0.8.4" }
 dashmap = { version = "6.0.1" }
@@ -71,7 +71,7 @@ dir-test = { version = "0.4.0" }
 dunce = { version = "1.0.5" }
 drop_bomb = { version = "0.1.5" }
 env_logger = { version = "0.11.0" }
-etcetera = { version = "0.8.0" }
+etcetera = { version = "0.10.0" }
 fern = { version = "0.7.0" }
 filetime = { version = "0.2.23" }
 getrandom = { version = "0.3.1" }
@@ -123,7 +123,7 @@ rayon = { version = "1.10.0" }
 regex = { version = "1.10.2" }
 rustc-hash = { version = "2.0.0" }
 # When updating salsa, make sure to also update the revision in `fuzz/Cargo.toml`
-salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "99be5d9917c3dd88e19735a82ef6bf39ba84bd7e" }
+salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "d758691ba17ee1a60c5356ea90888d529e1782ad" }
 schemars = { version = "0.8.16" }
 seahash = { version = "4.1.0" }
 serde = { version = "1.0.197", features = ["derive"] }
@@ -154,6 +154,7 @@ toml = { version = "0.8.11" }
 tracing = { version = "0.1.40" }
 tracing-flame = { version = "0.2.0" }
 tracing-indicatif = { version = "0.3.6" }
+tracing-log = { version = "0.2.0" }
 tracing-subscriber = { version = "0.3.18", default-features = false, features = [
     "env-filter",
     "fmt",
@@ -326,3 +327,9 @@ github-custom-job-permissions = { "build-docker" = { packages = "write", content
 install-updater = false
 # Path that installers should place binaries in
 install-path = ["$XDG_BIN_HOME/", "$XDG_DATA_HOME/../bin", "~/.local/bin"]
+# Temporarily allow changes to the `release` workflow, in which we pin actions
+# to a SHA instead of a tag (https://github.com/astral-sh/uv/issues/12253)
+allow-dirty = ["ci"]
+
+[workspace.metadata.dist.github-custom-runners]
+global = "depot-ubuntu-latest-4"

README.md

@@ -149,8 +149,8 @@ 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/0.9.10/install.sh | sh
-powershell -c "irm https://astral.sh/ruff/0.9.10/install.ps1 | iex"
+curl -LsSf https://astral.sh/ruff/0.11.2/install.sh | sh
+powershell -c "irm https://astral.sh/ruff/0.11.2/install.ps1 | iex"
 ```
 
 You can also install Ruff via [Homebrew](https://formulae.brew.sh/formula/ruff), [Conda](https://anaconda.org/conda-forge/ruff),
@@ -183,7 +183,7 @@ 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: v0.9.10
+  rev: v0.11.2
   hooks:
     # Run the linter.
     - id: ruff

crates/red_knot/docs/mypy_primer.md

@@ -0,0 +1,61 @@
+# Running `mypy_primer`
+
+## Basics
+
+For now, we use our own [fork of mypy primer]. It can be run using `uvx --from "…" mypy_primer`. For example, to see the help message, run:
+
+```sh
+uvx --from "git+https://github.com/astral-sh/mypy_primer.git@add-red-knot-support" mypy_primer -h
+```
+
+Alternatively, you can install the forked version of `mypy_primer` using:
+
+```sh
+uv tool install "git+https://github.com/astral-sh/mypy_primer.git@add-red-knot-support"
+```
+
+and then run it using `uvx mypy_primer` or just `mypy_primer`, if your `PATH` is set up accordingly (see: [Tool executables]).
+
+## Showing the diagnostics diff between two Git revisions
+
+To show the diagnostics diff between two Git revisions (e.g. your feature branch and `main`), run:
+
+```sh
+mypy_primer \
+    --type-checker knot \
+    --old origin/main \
+    --new my/feature \
+    --debug \
+    --output concise \
+    --project-selector '/black$'
+```
+
+This will show the diagnostics diff for the `black` project between the `main` branch and your `my/feature` branch. To run the
+diff for all projects, you currently need to copy the project-selector regex from the CI pipeline in `.github/workflows/mypy_primer.yaml`.
+
+You can also take a look at the [full list of ecosystem projects]. Note that some of them might still need a `knot_paths` configuration
+option to work correctly.
+
+## Avoiding recompilation
+
+If you want to run `mypy_primer` repeatedly, e.g. for different projects, but for the same combination of `--old` and `--new`, you
+can use set the `MYPY_PRIMER_NO_REBUILD` environment variable to avoid recompilation of Red Knot:
+
+```sh
+MYPY_PRIMER_NO_REBUILD=1 mypy_primer …
+```
+
+## Running from a local copy of the repository
+
+If you are working on a local branch, you can use `mypy_primer`'s `--repo` option to specify the path to your local copy of the `ruff` repository.
+This allows `mypy_primer` to check out local branches:
+
+```sh
+mypy_primer --repo /path/to/ruff --old origin/main --new my/local-branch …
+```
+
+Note that you might need to clean up `/tmp/mypy_primer` in order for this to work correctly.
+
+[fork of mypy primer]: https://github.com/astral-sh/mypy_primer/tree/add-red-knot-support
+[full list of ecosystem projects]: https://github.com/astral-sh/mypy_primer/blob/add-red-knot-support/mypy_primer/projects.py
+[tool executables]: https://docs.astral.sh/uv/concepts/tools/#tool-executables

crates/red_knot/src/args.rs

@@ -50,6 +50,8 @@ pub(crate) struct CheckCommand {
 
     /// Path to the Python installation from which Red Knot resolves type information and third-party dependencies.
     ///
+    /// If not specified, Red Knot will look at the `VIRTUAL_ENV` environment variable.
+    ///
     /// Red Knot will search in the path's `site-packages` directories for type information and
     /// third-party imports.
     ///
@@ -75,6 +77,14 @@ pub(crate) struct CheckCommand {
     #[clap(flatten)]
     pub(crate) rules: RulesArg,
 
+    /// The format to use for printing diagnostic messages.
+    #[arg(long)]
+    pub(crate) output_format: Option<OutputFormat>,
+
+    /// Control when colored output is used.
+    #[arg(long, value_name = "WHEN")]
+    pub(crate) color: Option<TerminalColor>,
+
     /// Use exit code 1 if there are any warning-level diagnostics.
     #[arg(long, conflicts_with = "exit_zero", default_missing_value = "true", num_args=0..1)]
     pub(crate) error_on_warning: Option<bool>,
@@ -117,6 +127,9 @@ impl CheckCommand {
                 ..EnvironmentOptions::default()
             }),
             terminal: Some(TerminalOptions {
+                output_format: self
+                    .output_format
+                    .map(|output_format| RangedValue::cli(output_format.into())),
                 error_on_warning: self.error_on_warning,
             }),
             rules,
@@ -211,3 +224,46 @@ impl clap::Args for RulesArg {
         Self::augment_args(cmd)
     }
 }
+
+/// The diagnostic output format.
+#[derive(Copy, Clone, Hash, Debug, PartialEq, Eq, PartialOrd, Ord, Default, clap::ValueEnum)]
+pub enum OutputFormat {
+    /// Print diagnostics verbosely, with context and helpful hints.
+    ///
+    /// Diagnostic messages may include additional context and
+    /// annotations on the input to help understand the message.
+    #[default]
+    #[value(name = "full")]
+    Full,
+    /// Print diagnostics concisely, one per line.
+    ///
+    /// This will guarantee that each diagnostic is printed on
+    /// a single line. Only the most important or primary aspects
+    /// of the diagnostic are included. Contextual information is
+    /// dropped.
+    #[value(name = "concise")]
+    Concise,
+}
+
+impl From<OutputFormat> for ruff_db::diagnostic::DiagnosticFormat {
+    fn from(format: OutputFormat) -> ruff_db::diagnostic::DiagnosticFormat {
+        match format {
+            OutputFormat::Full => Self::Full,
+            OutputFormat::Concise => Self::Concise,
+        }
+    }
+}
+
+/// Control when colored output is used.
+#[derive(Copy, Clone, Hash, Debug, PartialEq, Eq, PartialOrd, Ord, Default, clap::ValueEnum)]
+pub(crate) enum TerminalColor {
+    /// Display colors if the output goes to an interactive terminal.
+    #[default]
+    Auto,
+
+    /// Always display colors.
+    Always,
+
+    /// Never display colors.
+    Never,
+}

crates/red_knot/src/main.rs

@@ -4,7 +4,7 @@ use std::process::{ExitCode, Termination};
 use anyhow::Result;
 use std::sync::Mutex;
 
-use crate::args::{Args, CheckCommand, Command};
+use crate::args::{Args, CheckCommand, Command, TerminalColor};
 use crate::logging::setup_tracing;
 use anyhow::{anyhow, Context};
 use clap::Parser;
@@ -76,10 +76,14 @@ pub(crate) fn version() -> Result<()> {
 }
 
 fn run_check(args: CheckCommand) -> anyhow::Result<ExitStatus> {
+    set_colored_override(args.color);
+
     let verbosity = args.verbosity.level();
     countme::enable(verbosity.is_trace());
     let _guard = setup_tracing(verbosity)?;
 
+    tracing::debug!("Version: {}", version::version());
+
     // The base path to which all CLI arguments are relative to.
     let cwd = {
         let cwd = std::env::current_dir().context("Failed to get the current working directory")?;
@@ -255,15 +259,16 @@ impl MainLoop {
                     result,
                     revision: check_revision,
                 } => {
+                    let terminal_settings = db.project().settings(db).terminal();
                     let display_config = DisplayDiagnosticConfig::default()
+                        .format(terminal_settings.output_format)
                         .color(colored::control::SHOULD_COLORIZE.should_colorize());
 
-                    let min_error_severity =
-                        if db.project().settings(db).terminal().error_on_warning {
-                            Severity::Warning
-                        } else {
-                            Severity::Error
-                        };
+                    let min_error_severity = if terminal_settings.error_on_warning {
+                        Severity::Warning
+                    } else {
+                        Severity::Error
+                    };
 
                     if check_revision == revision {
                         if db.project().files(db).is_empty() {
@@ -360,3 +365,21 @@ enum MainLoopMessage {
     ApplyChanges(Vec<watch::ChangeEvent>),
     Exit,
 }
+
+fn set_colored_override(color: Option<TerminalColor>) {
+    let Some(color) = color else {
+        return;
+    };
+
+    match color {
+        TerminalColor::Auto => {
+            colored::control::unset_override();
+        }
+        TerminalColor::Always => {
+            colored::control::set_override(true);
+        }
+        TerminalColor::Never => {
+            colored::control::set_override(false);
+        }
+    }
+}

crates/red_knot/tests/cli.rs

@@ -86,7 +86,7 @@ fn cli_arguments_are_relative_to_the_current_directory() -> anyhow::Result<()> {
             "libs/utils.py",
             r#"
             def add(a: int, b: int) -> int:
-                a + b
+                return a + b
             "#,
         ),
         (
@@ -158,7 +158,7 @@ fn paths_in_configuration_files_are_relative_to_the_project_root() -> anyhow::Re
             "libs/utils.py",
             r#"
             def add(a: int, b: int) -> int:
-                a + b
+                return a + b
             "#,
         ),
         (
@@ -219,7 +219,7 @@ fn configuration_rule_severity() -> anyhow::Result<()> {
     5 |     x = a
     6 |
     7 | print(x)  # possibly-unresolved-reference
-      |       - Name `x` used when possibly not defined
+      |       ^ Name `x` used when possibly not defined
       |
 
     Found 2 diagnostics
@@ -244,7 +244,7 @@ fn configuration_rule_severity() -> anyhow::Result<()> {
      --> <temp_dir>/test.py:2:5
       |
     2 | y = 4 / 0
-      |     ----- Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
     3 |
     4 | for a in range(0, y):
       |
@@ -306,7 +306,7 @@ fn cli_rule_severity() -> anyhow::Result<()> {
     7 |     x = a
     8 |
     9 | print(x)  # possibly-unresolved-reference
-      |       - Name `x` used when possibly not defined
+      |       ^ Name `x` used when possibly not defined
       |
 
     Found 3 diagnostics
@@ -331,7 +331,7 @@ fn cli_rule_severity() -> anyhow::Result<()> {
      --> <temp_dir>/test.py:2:8
       |
     2 | import does_not_exit
-      |        ------------- Cannot resolve import `does_not_exit`
+      |        ^^^^^^^^^^^^^ Cannot resolve import `does_not_exit`
     3 |
     4 | y = 4 / 0
       |
@@ -342,7 +342,7 @@ fn cli_rule_severity() -> anyhow::Result<()> {
     2 | import does_not_exit
     3 |
     4 | y = 4 / 0
-      |     ----- Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
     5 |
     6 | for a in range(0, y):
       |
@@ -393,7 +393,7 @@ fn cli_rule_severity_precedence() -> anyhow::Result<()> {
     5 |     x = a
     6 |
     7 | print(x)  # possibly-unresolved-reference
-      |       - Name `x` used when possibly not defined
+      |       ^ Name `x` used when possibly not defined
       |
 
     Found 2 diagnostics
@@ -419,7 +419,7 @@ fn cli_rule_severity_precedence() -> anyhow::Result<()> {
      --> <temp_dir>/test.py:2:5
       |
     2 | y = 4 / 0
-      |     ----- Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
     3 |
     4 | for a in range(0, y):
       |
@@ -456,7 +456,7 @@ fn configuration_unknown_rules() -> anyhow::Result<()> {
       |
     2 | [tool.knot.rules]
     3 | division-by-zer = "warn" # incorrect rule name
-      | --------------- Unknown lint rule `division-by-zer`
+      | ^^^^^^^^^^^^^^^ Unknown lint rule `division-by-zer`
       |
 
     Found 1 diagnostic
@@ -498,7 +498,7 @@ fn exit_code_only_warnings() -> anyhow::Result<()> {
      --> <temp_dir>/test.py:1:7
       |
     1 | print(x)  # [unresolved-reference]
-      |       - Name `x` used when not defined
+      |       ^ Name `x` used when not defined
       |
 
     Found 1 diagnostic
@@ -528,7 +528,7 @@ fn exit_code_only_info() -> anyhow::Result<()> {
       |
     2 | from typing_extensions import reveal_type
     3 | reveal_type(1)
-      | -------------- info: Revealed type is `Literal[1]`
+      | ^^^^^^^^^^^^^^ Revealed type is `Literal[1]`
       |
 
     Found 1 diagnostic
@@ -558,7 +558,7 @@ fn exit_code_only_info_and_error_on_warning_is_true() -> anyhow::Result<()> {
       |
     2 | from typing_extensions import reveal_type
     3 | reveal_type(1)
-      | -------------- info: Revealed type is `Literal[1]`
+      | ^^^^^^^^^^^^^^ Revealed type is `Literal[1]`
       |
 
     Found 1 diagnostic
@@ -581,7 +581,7 @@ fn exit_code_no_errors_but_error_on_warning_is_true() -> anyhow::Result<()> {
      --> <temp_dir>/test.py:1:7
       |
     1 | print(x)  # [unresolved-reference]
-      |       - Name `x` used when not defined
+      |       ^ Name `x` used when not defined
       |
 
     Found 1 diagnostic
@@ -613,7 +613,7 @@ fn exit_code_no_errors_but_error_on_warning_is_enabled_in_configuration() -> any
      --> <temp_dir>/test.py:1:7
       |
     1 | print(x)  # [unresolved-reference]
-      |       - Name `x` used when not defined
+      |       ^ Name `x` used when not defined
       |
 
     Found 1 diagnostic
@@ -642,7 +642,7 @@ fn exit_code_both_warnings_and_errors() -> anyhow::Result<()> {
      --> <temp_dir>/test.py:2:7
       |
     2 | print(x)     # [unresolved-reference]
-      |       - Name `x` used when not defined
+      |       ^ Name `x` used when not defined
     3 | print(4[1])  # [non-subscriptable]
       |
 
@@ -680,7 +680,7 @@ fn exit_code_both_warnings_and_errors_and_error_on_warning_is_true() -> anyhow::
      --> <temp_dir>/test.py:2:7
       |
     2 | print(x)     # [unresolved-reference]
-      |       - Name `x` used when not defined
+      |       ^ Name `x` used when not defined
     3 | print(4[1])  # [non-subscriptable]
       |
 
@@ -718,7 +718,7 @@ fn exit_code_exit_zero_is_true() -> anyhow::Result<()> {
      --> <temp_dir>/test.py:2:7
       |
     2 | print(x)     # [unresolved-reference]
-      |       - Name `x` used when not defined
+      |       ^ Name `x` used when not defined
     3 | print(4[1])  # [non-subscriptable]
       |
 
@@ -778,7 +778,7 @@ fn user_configuration() -> anyhow::Result<()> {
      --> <temp_dir>/project/main.py:2:5
       |
     2 | y = 4 / 0
-      |     ----- Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
     3 |
     4 | for a in range(0, y):
       |
@@ -789,7 +789,7 @@ fn user_configuration() -> anyhow::Result<()> {
     5 |     x = a
     6 |
     7 | print(x)
-      |       - Name `x` used when possibly not defined
+      |       ^ Name `x` used when possibly not defined
       |
 
     Found 2 diagnostics
@@ -820,7 +820,7 @@ fn user_configuration() -> anyhow::Result<()> {
      --> <temp_dir>/project/main.py:2:5
       |
     2 | y = 4 / 0
-      |     ----- Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
     3 |
     4 | for a in range(0, y):
       |
@@ -967,6 +967,30 @@ fn check_non_existing_path() -> anyhow::Result<()> {
     Ok(())
 }
 
+#[test]
+fn concise_diagnostics() -> anyhow::Result<()> {
+    let case = TestCase::with_file(
+        "test.py",
+        r#"
+        print(x)     # [unresolved-reference]
+        print(4[1])  # [non-subscriptable]
+        "#,
+    )?;
+
+    assert_cmd_snapshot!(case.command().arg("--output-format=concise"), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    warning[lint:unresolved-reference] <temp_dir>/test.py:2:7: Name `x` used when not defined
+    error[lint:non-subscriptable] <temp_dir>/test.py:3:7: Cannot subscript object of type `Literal[4]` with no `__getitem__` method
+    Found 2 diagnostics
+
+    ----- stderr -----
+    ");
+
+    Ok(())
+}
+
 struct TestCase {
     _temp_dir: TempDir,
     _settings_scope: SettingsBindDropGuard,

crates/red_knot/tests/file_watching.rs

@@ -1,5 +1,3 @@
-#![allow(clippy::disallowed_names)]
-
 use std::collections::HashSet;
 use std::io::Write;
 use std::time::{Duration, Instant};
@@ -16,7 +14,7 @@ use ruff_db::source::source_text;
 use ruff_db::system::{
     OsSystem, System, SystemPath, SystemPathBuf, UserConfigDirectoryOverrideGuard,
 };
-use ruff_db::Upcast;
+use ruff_db::{Db as _, Upcast};
 use ruff_python_ast::PythonVersion;
 
 struct TestCase {
@@ -1790,3 +1788,82 @@ fn changes_to_user_configuration() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+/// Tests that renaming a file from `lib.py` to `Lib.py` is correctly reflected.
+///
+/// This test currently fails on case-insensitive systems because `Files` is case-sensitive
+/// but the `System::metadata` call isn't. This means that
+/// Red Knot considers both `Lib.py` and `lib.py` to exist when only `lib.py` does
+///
+/// The incoming change events then are no-ops because they don't change either file's
+/// status nor does it update their last modified time (renaming a file doesn't bump it's
+/// last modified timestamp).
+///
+/// Fixing this requires to either make `Files` case-insensitive and store the
+/// real-case path (if it differs) on `File` or make `Files` use a
+/// case-sensitive `System::metadata` call. This does open the question if all
+/// `System` calls should be case sensitive. This would be the most consistent
+/// but might be hard to pull off.
+///
+/// What the right solution is also depends on if Red Knot itself should be case
+/// sensitive or not. E.g. should `include="src"` be case sensitive on all systems
+/// or only on case-sensitive systems?
+///
+/// Lastly, whatever solution we pick must also work well with VS Code which,
+/// unfortunately ,doesn't propagate casing-only renames.
+/// <https://github.com/rust-lang/rust-analyzer/issues/9581>
+#[ignore]
+#[test]
+fn rename_files_casing_only() -> anyhow::Result<()> {
+    let mut case = setup([("lib.py", "class Foo: ...")])?;
+
+    assert!(
+        resolve_module(case.db(), &ModuleName::new("lib").unwrap()).is_some(),
+        "Expected `lib` module to exist."
+    );
+    assert_eq!(
+        resolve_module(case.db(), &ModuleName::new("Lib").unwrap()),
+        None,
+        "Expected `Lib` module not to exist"
+    );
+
+    // Now rename `lib.py` to `Lib.py`
+    if case.db().system().case_sensitivity().is_case_sensitive() {
+        std::fs::rename(
+            case.project_path("lib.py").as_std_path(),
+            case.project_path("Lib.py").as_std_path(),
+        )
+        .context("Failed to rename `lib.py` to `Lib.py`")?;
+    } else {
+        // On case-insensitive file systems, renaming a file to a different casing is a no-op.
+        // Rename to a different name first
+        std::fs::rename(
+            case.project_path("lib.py").as_std_path(),
+            case.project_path("temp.py").as_std_path(),
+        )
+        .context("Failed to rename `lib.py` to `temp.py`")?;
+
+        std::fs::rename(
+            case.project_path("temp.py").as_std_path(),
+            case.project_path("Lib.py").as_std_path(),
+        )
+        .context("Failed to rename `temp.py` to `Lib.py`")?;
+    }
+
+    let changes = case.stop_watch(event_for_file("Lib.py"));
+    case.apply_changes(changes);
+
+    // Resolving `lib` should now fail but `Lib` should now succeed
+    assert_eq!(
+        resolve_module(case.db(), &ModuleName::new("lib").unwrap()),
+        None,
+        "Expected `lib` module to no longer exist."
+    );
+
+    assert!(
+        resolve_module(case.db(), &ModuleName::new("Lib").unwrap()).is_some(),
+        "Expected `Lib` module to exist"
+    );
+
+    Ok(())
+}

crates/red_knot_project/src/db.rs

@@ -59,9 +59,8 @@ impl ProjectDatabase {
         self.with_db(|db| db.project().check(db))
     }
 
+    #[tracing::instrument(level = "debug", skip(self))]
     pub fn check_file(&self, file: File) -> Result<Vec<Box<dyn OldDiagnosticTrait>>, Cancelled> {
-        let _span = tracing::debug_span!("check_file", file=%file.path(self)).entered();
-
         self.with_db(|db| self.project().check_file(db, file))
     }
 

crates/red_knot_project/src/lib.rs

@@ -195,7 +195,8 @@ impl Project {
                 let project_span = project_span.clone();
 
                 scope.spawn(move |_| {
-                    let check_file_span = tracing::debug_span!(parent: &project_span, "check_file", file=%file.path(&db));
+                    let check_file_span =
+                        tracing::debug_span!(parent: &project_span, "check_file", ?file);
                     let _entered = check_file_span.entered();
 
                     let file_diagnostics = check_file_impl(&db, file);
@@ -325,7 +326,7 @@ impl Project {
         self.files(db).contains(&file)
     }
 
-    #[tracing::instrument(level = "debug", skip(db))]
+    #[tracing::instrument(level = "debug", skip(self, db))]
     pub fn remove_file(self, db: &mut dyn Db, file: File) {
         tracing::debug!(
             "Removing file `{}` from project `{}`",

crates/red_knot_project/src/metadata/options.rs

@@ -2,7 +2,7 @@ use crate::metadata::value::{RangedValue, RelativePathBuf, ValueSource, ValueSou
 use crate::Db;
 use red_knot_python_semantic::lint::{GetLintError, Level, LintSource, RuleSelection};
 use red_knot_python_semantic::{ProgramSettings, PythonPath, PythonPlatform, SearchPathSettings};
-use ruff_db::diagnostic::{DiagnosticId, OldDiagnosticTrait, Severity, Span};
+use ruff_db::diagnostic::{DiagnosticFormat, DiagnosticId, OldDiagnosticTrait, Severity, Span};
 use ruff_db::files::system_path_to_file;
 use ruff_db::system::{System, SystemPath};
 use ruff_macros::Combine;
@@ -106,9 +106,14 @@ impl Options {
             custom_typeshed: typeshed.map(|path| path.absolute(project_root, system)),
             python_path: python
                 .map(|python_path| {
-                    PythonPath::SysPrefix(python_path.absolute(project_root, system))
+                    PythonPath::from_cli_flag(python_path.absolute(project_root, system))
                 })
-                .unwrap_or(PythonPath::KnownSitePackages(vec![])),
+                .or_else(|| {
+                    std::env::var("VIRTUAL_ENV")
+                        .ok()
+                        .map(PythonPath::from_virtual_env_var)
+                })
+                .unwrap_or_else(|| PythonPath::KnownSitePackages(vec![])),
         }
     }
 
@@ -120,6 +125,11 @@ impl Options {
 
         if let Some(terminal) = self.terminal.as_ref() {
             settings.set_terminal(TerminalSettings {
+                output_format: terminal
+                    .output_format
+                    .as_deref()
+                    .copied()
+                    .unwrap_or_default(),
                 error_on_warning: terminal.error_on_warning.unwrap_or_default(),
             });
         }
@@ -277,6 +287,11 @@ impl FromIterator<(RangedValue<String>, RangedValue<Level>)> for Rules {
 #[serde(rename_all = "kebab-case", deny_unknown_fields)]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct TerminalOptions {
+    /// The format to use for printing diagnostic messages.
+    ///
+    /// Defaults to `full`.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub output_format: Option<RangedValue<DiagnosticFormat>>,
     /// Use exit code 1 if there are any warning-level diagnostics.
     ///
     /// Defaults to `false`.

crates/red_knot_project/src/metadata/settings.rs

@@ -1,6 +1,7 @@
 use std::sync::Arc;
 
 use red_knot_python_semantic::lint::RuleSelection;
+use ruff_db::diagnostic::DiagnosticFormat;
 
 /// The resolved [`super::Options`] for the project.
 ///
@@ -49,5 +50,6 @@ impl Settings {
 
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
 pub struct TerminalSettings {
+    pub output_format: DiagnosticFormat,
     pub error_on_warning: bool,
 }

crates/red_knot_project/tests/check.rs

@@ -279,23 +279,4 @@ impl SourceOrderVisitor<'_> for PullTypesVisitor<'_> {
 
 /// Whether or not the .py/.pyi version of this file is expected to fail
 #[rustfmt::skip]
-const KNOWN_FAILURES: &[(&str, bool, bool)] = &[
-    // related to circular references in nested functions
-    ("crates/ruff_linter/resources/test/fixtures/flake8_return/RET503.py", false, true),
-    // related to circular references in class definitions
-    ("crates/ruff_linter/resources/test/fixtures/pyflakes/F821_26.py", true, true),
-    ("crates/ruff_linter/resources/test/fixtures/pyflakes/F821_27.py", true, true),
-    ("crates/ruff_linter/resources/test/fixtures/pyflakes/F811_19.py", true, false),
-    ("crates/ruff_linter/resources/test/fixtures/pyupgrade/UP039.py", true, false),
-    // related to circular references in type aliases (salsa cycle panic):
-    ("crates/ruff_python_parser/resources/inline/err/type_alias_invalid_value_expr.py", true, true),
-    ("crates/ruff_linter/resources/test/fixtures/flake8_type_checking/TC008.py", true, true),
-    // related to circular references in f-string annotations (invalid syntax)
-    ("crates/ruff_linter/resources/test/fixtures/pyflakes/F821_15.py", true, true),
-    ("crates/ruff_linter/resources/test/fixtures/pyflakes/F821_14.py", false, true),
-    // related to circular references in stub type annotations (salsa cycle panic):
-    ("crates/ruff_linter/resources/test/fixtures/pycodestyle/E501_4.py", false, true),
-    ("crates/ruff_linter/resources/test/fixtures/pyflakes/F401_0.py", false, true),
-    ("crates/ruff_linter/resources/test/fixtures/pyflakes/F401_12.py", false, true),
-    ("crates/ruff_linter/resources/test/fixtures/pyflakes/F401_14.py", false, true),
-];
+const KNOWN_FAILURES: &[(&str, bool, bool)] = &[];

crates/red_knot_python_semantic/resources/mdtest/annotations/annotated.md

@@ -29,7 +29,7 @@ It is invalid to parameterize `Annotated` with less than two arguments.
 ```py
 from typing_extensions import Annotated
 
-# error: [invalid-type-form] "`Annotated` requires at least two arguments when used in an annotation or type expression"
+# error: [invalid-type-form] "`typing.Annotated` requires at least two arguments when used in a type expression"
 def _(x: Annotated):
     reveal_type(x)  # revealed: Unknown
 
@@ -39,11 +39,11 @@ def _(flag: bool):
     else:
         X = bool
 
-    # error: [invalid-type-form] "`Annotated` requires at least two arguments when used in an annotation or type expression"
+    # error: [invalid-type-form] "`typing.Annotated` requires at least two arguments when used in a type expression"
     def f(y: X):
         reveal_type(y)  # revealed: Unknown | bool
 
-# error: [invalid-type-form] "`Annotated` requires at least two arguments when used in an annotation or type expression"
+# error: [invalid-type-form] "`typing.Annotated` requires at least two arguments when used in a type expression"
 def _(x: Annotated | bool):
     reveal_type(x)  # revealed: Unknown | bool
 
@@ -73,12 +73,10 @@ Inheriting from `Annotated[T, ...]` is equivalent to inheriting from `T` itself.
 ```py
 from typing_extensions import Annotated
 
-# TODO: False positive
-# error: [invalid-base]
 class C(Annotated[int, "foo"]): ...
 
 # TODO: Should be `tuple[Literal[C], Literal[int], Literal[object]]`
-reveal_type(C.__mro__)  # revealed: tuple[Literal[C], Unknown, Literal[object]]
+reveal_type(C.__mro__)  # revealed: tuple[Literal[C], @Todo(Inference of subscript on special form), Literal[object]]
 ```
 
 ### Not parameterized

crates/red_knot_python_semantic/resources/mdtest/annotations/callable.md

@@ -47,8 +47,10 @@ def _(c: Callable[42, str]):
 Or, when one of the parameter type is invalid in the list:
 
 ```py
+# error: [invalid-type-form] "Int literals are not allowed in this context in a type expression"
+# error: [invalid-type-form] "Boolean literals are not allowed in this context in a type expression"
 def _(c: Callable[[int, 42, str, False], None]):
-    # revealed: (int, @Todo(number literal in type expression), str, @Todo(boolean literal in type expression), /) -> None
+    # revealed: (int, Unknown, str, Unknown, /) -> None
     reveal_type(c)
 ```
 
@@ -61,7 +63,7 @@ from typing import Callable
 
 # error: [invalid-type-form] "Special form `typing.Callable` expected exactly two arguments (parameter types and return type)"
 def _(c: Callable[[int, str]]):
-    reveal_type(c)  # revealed: (int, str, /) -> Unknown
+    reveal_type(c)  # revealed: (...) -> Unknown
 ```
 
 Or, an ellipsis:
@@ -72,6 +74,18 @@ def _(c: Callable[...]):
     reveal_type(c)  # revealed: (...) -> Unknown
 ```
 
+Or something else that's invalid in a type expression generally:
+
+```py
+# fmt: off
+
+def _(c: Callable[  # error: [invalid-type-form] "Special form `typing.Callable` expected exactly two arguments (parameter types and return type)"
+            {1, 2}  # error: [invalid-type-form] "The first argument to `Callable` must be either a list of types, ParamSpec, Concatenate, or `...`"
+        ]
+    ):
+    reveal_type(c)  # revealed: (...) -> Unknown
+```
+
 ### More than two arguments
 
 We can't reliably infer the callable type if there are more then 2 arguments because we don't know
@@ -85,6 +99,48 @@ def _(c: Callable[[int], str, str]):
     reveal_type(c)  # revealed: (...) -> Unknown
 ```
 
+### List as the second argument
+
+```py
+from typing import Callable
+
+# fmt: off
+
+def _(c: Callable[
+            int,  # error: [invalid-type-form] "The first argument to `Callable` must be either a list of types, ParamSpec, Concatenate, or `...`"
+            [str]  # error: [invalid-type-form] "List literals are not allowed in this context in a type expression"
+        ]
+    ):
+    reveal_type(c)  # revealed: (...) -> Unknown
+```
+
+### List as both arguments
+
+```py
+from typing import Callable
+
+# error: [invalid-type-form] "List literals are not allowed in this context in a type expression"
+def _(c: Callable[[int], [str]]):
+    reveal_type(c)  # revealed: (int, /) -> Unknown
+```
+
+### Three list arguments
+
+```py
+from typing import Callable
+
+# fmt: off
+
+
+def _(c: Callable[  # error: [invalid-type-form] "Special form `typing.Callable` expected exactly two arguments (parameter types and return type)"
+            [int],
+            [str],  # error: [invalid-type-form] "List literals are not allowed in this context in a type expression"
+            [bytes]  # error: [invalid-type-form] "List literals are not allowed in this context in a type expression"
+        ]
+    ):
+    reveal_type(c)  # revealed: (...) -> Unknown
+```
+
 ## Simple
 
 A simple `Callable` with multiple parameters and a return type:
@@ -192,4 +248,20 @@ def _(c: Callable[[int, Unpack[Ts]], int]):
     reveal_type(c)  # revealed: (*args: @Todo(todo signature *args), **kwargs: @Todo(todo signature **kwargs)) -> int
 ```
 
+## Member lookup
+
+```py
+from typing import Callable
+
+def _(c: Callable[[int], int]):
+    reveal_type(c.__init__)  # revealed: Literal[__init__]
+    reveal_type(c.__class__)  # revealed: type
+
+    # TODO: The member lookup for `Callable` uses `object` which does not have a `__call__`
+    # attribute. We could special case `__call__` in this context. Refer to
+    # https://github.com/astral-sh/ruff/pull/16493#discussion_r1985098508 for more details.
+    # error: [unresolved-attribute] "Type `(int, /) -> int` has no attribute `__call__`"
+    reveal_type(c.__call__)  # revealed: Unknown
+```
+
 [gradual form]: https://typing.readthedocs.io/en/latest/spec/glossary.html#term-gradual-form

crates/red_knot_python_semantic/resources/mdtest/annotations/deferred.md

@@ -38,7 +38,8 @@ If `__future__.annotations` is imported, annotations *are* deferred.
 ```py
 from __future__ import annotations
 
-def get_foo() -> Foo: ...
+def get_foo() -> Foo:
+    return Foo()
 
 class Foo: ...
 

crates/red_knot_python_semantic/resources/mdtest/annotations/invalid.md

@@ -9,6 +9,8 @@ import typing
 from knot_extensions import AlwaysTruthy, AlwaysFalsy
 from typing_extensions import Literal, Never
 
+class A: ...
+
 def _(
     a: type[int],
     b: AlwaysTruthy,
@@ -18,28 +20,95 @@ def _(
     f: Literal[b"foo"],
     g: tuple[int, str],
     h: Never,
+    i: int,
+    j: A,
 ):
     def foo(): ...
     def invalid(
-        i: a,  # error: [invalid-type-form] "Variable of type `type[int]` is not allowed in a type expression"
-        j: b,  # error: [invalid-type-form]
-        k: c,  # error: [invalid-type-form]
-        l: d,  # error: [invalid-type-form]
-        m: e,  # error: [invalid-type-form]
-        n: f,  # error: [invalid-type-form]
-        o: g,  # error: [invalid-type-form]
-        p: h,  # error: [invalid-type-form]
-        q: typing,  # error: [invalid-type-form]
-        r: foo,  # error: [invalid-type-form]
+        a_: a,  # error: [invalid-type-form] "Variable of type `type[int]` is not allowed in a type expression"
+        b_: b,  # error: [invalid-type-form]
+        c_: c,  # error: [invalid-type-form]
+        d_: d,  # error: [invalid-type-form]
+        e_: e,  # error: [invalid-type-form]
+        f_: f,  # error: [invalid-type-form]
+        g_: g,  # error: [invalid-type-form]
+        h_: h,  # error: [invalid-type-form]
+        i_: typing,  # error: [invalid-type-form]
+        j_: foo,  # error: [invalid-type-form]
+        k_: i,  # error: [invalid-type-form] "Variable of type `int` is not allowed in a type expression"
+        l_: j,  # error: [invalid-type-form] "Variable of type `A` is not allowed in a type expression"
     ):
-        reveal_type(i)  # revealed: Unknown
-        reveal_type(j)  # revealed: Unknown
-        reveal_type(k)  # revealed: Unknown
-        reveal_type(l)  # revealed: Unknown
-        reveal_type(m)  # revealed: Unknown
-        reveal_type(n)  # revealed: Unknown
-        reveal_type(o)  # revealed: Unknown
-        reveal_type(p)  # revealed: Unknown
-        reveal_type(q)  # revealed: Unknown
-        reveal_type(r)  # revealed: Unknown
+        reveal_type(a_)  # revealed: Unknown
+        reveal_type(b_)  # revealed: Unknown
+        reveal_type(c_)  # revealed: Unknown
+        reveal_type(d_)  # revealed: Unknown
+        reveal_type(e_)  # revealed: Unknown
+        reveal_type(f_)  # revealed: Unknown
+        reveal_type(g_)  # revealed: Unknown
+        reveal_type(h_)  # revealed: Unknown
+        reveal_type(i_)  # revealed: Unknown
+        reveal_type(j_)  # revealed: Unknown
+```
+
+## Invalid AST nodes
+
+```py
+def bar() -> None:
+    return None
+
+def _(
+    a: 1,  # error: [invalid-type-form] "Int literals are not allowed in this context in a type expression"
+    b: 2.3,  # error: [invalid-type-form] "Float literals are not allowed in type expressions"
+    c: 4j,  # error: [invalid-type-form] "Complex literals are not allowed in type expressions"
+    d: True,  # error: [invalid-type-form] "Boolean literals are not allowed in this context in a type expression"
+    e: int | b"foo",  # error: [invalid-type-form] "Bytes literals are not allowed in this context in a type expression"
+    f: 1 and 2,  # error: [invalid-type-form] "Boolean operations are not allowed in type expressions"
+    g: 1 or 2,  # error: [invalid-type-form] "Boolean operations are not allowed in type expressions"
+    h: (foo := 1),  # error: [invalid-type-form] "Named expressions are not allowed in type expressions"
+    i: not 1,  # error: [invalid-type-form] "Unary operations are not allowed in type expressions"
+    j: lambda: 1,  # error: [invalid-type-form] "`lambda` expressions are not allowed in type expressions"
+    k: 1 if True else 2,  # error: [invalid-type-form] "`if` expressions are not allowed in type expressions"
+    l: await 1,  # error: [invalid-type-form] "`await` expressions are not allowed in type expressions"
+    m: (yield 1),  # error: [invalid-type-form] "`yield` expressions are not allowed in type expressions"
+    n: (yield from [1]),  # error: [invalid-type-form] "`yield from` expressions are not allowed in type expressions"
+    o: 1 < 2,  # error: [invalid-type-form] "Comparison expressions are not allowed in type expressions"
+    p: bar(),  # error: [invalid-type-form] "Function calls are not allowed in type expressions"
+    q: int | f"foo",  # error: [invalid-type-form] "F-strings are not allowed in type expressions"
+    r: [1, 2, 3][1:2],  # error: [invalid-type-form] "Slices are not allowed in type expressions"
+):
+    reveal_type(a)  # revealed: Unknown
+    reveal_type(b)  # revealed: Unknown
+    reveal_type(c)  # revealed: Unknown
+    reveal_type(d)  # revealed: Unknown
+    reveal_type(e)  # revealed: int | Unknown
+    reveal_type(f)  # revealed: Unknown
+    reveal_type(g)  # revealed: Unknown
+    reveal_type(h)  # revealed: Unknown
+    reveal_type(i)  # revealed: Unknown
+    reveal_type(j)  # revealed: Unknown
+    reveal_type(k)  # revealed: Unknown
+    reveal_type(p)  # revealed: Unknown
+    reveal_type(q)  # revealed: int | Unknown
+    reveal_type(r)  # revealed: @Todo(generics)
+```
+
+## Invalid Collection based AST nodes
+
+```py
+def _(
+    a: {1: 2},  # error: [invalid-type-form] "Dict literals are not allowed in type expressions"
+    b: {1, 2},  # error: [invalid-type-form] "Set literals are not allowed in type expressions"
+    c: {k: v for k, v in [(1, 2)]},  # error: [invalid-type-form] "Dict comprehensions are not allowed in type expressions"
+    d: [k for k in [1, 2]],  # error: [invalid-type-form] "List comprehensions are not allowed in type expressions"
+    e: {k for k in [1, 2]},  # error: [invalid-type-form] "Set comprehensions are not allowed in type expressions"
+    f: (k for k in [1, 2]),  # error: [invalid-type-form] "Generator expressions are not allowed in type expressions"
+    g: [int, str],  # error: [invalid-type-form] "List literals are not allowed in this context in a type expression"
+):
+    reveal_type(a)  # revealed: Unknown
+    reveal_type(b)  # revealed: Unknown
+    reveal_type(c)  # revealed: Unknown
+    reveal_type(d)  # revealed: Unknown
+    reveal_type(e)  # revealed: Unknown
+    reveal_type(f)  # revealed: Unknown
+    reveal_type(g)  # revealed: Unknown
 ```

crates/red_knot_python_semantic/resources/mdtest/annotations/literal.md

@@ -127,6 +127,13 @@ Literal: _SpecialForm
 ```py
 from other import Literal
 
+# TODO: can we add a subdiagnostic here saying something like:
+#
+#     `other.Literal` and `typing.Literal` have similar names, but are different symbols and don't have the same semantics
+#
+# ?
+#
+# error: [invalid-type-form] "Int literals are not allowed in this context in a type expression"
 a1: Literal[26]
 
 def f():
@@ -149,7 +156,7 @@ def f():
 ```py
 from typing import Literal
 
-# error: [invalid-type-form] "`Literal` requires at least one argument when used in a type expression"
+# error: [invalid-type-form] "`typing.Literal` requires at least one argument when used in a type expression"
 def _(x: Literal):
     reveal_type(x)  # revealed: Unknown
 ```

crates/red_knot_python_semantic/resources/mdtest/annotations/new_types.md

@@ -0,0 +1,20 @@
+# NewType
+
+Currently, red-knot doesn't support `typing.NewType` in type annotations.
+
+## Valid forms
+
+```py
+from typing_extensions import NewType
+from types import GenericAlias
+
+A = NewType("A", int)
+B = GenericAlias(A, ())
+
+def _(
+    a: A,
+    b: B,
+):
+    reveal_type(a)  # revealed: @Todo(Support for `typing.NewType` instances in type expressions)
+    reveal_type(b)  # revealed: @Todo(Support for `typing.GenericAlias` instances in type expressions)
+```

crates/red_knot_python_semantic/resources/mdtest/annotations/optional.md

@@ -45,3 +45,13 @@ def f():
     # revealed: int | None
     reveal_type(a)
 ```
+
+## Invalid
+
+```py
+from typing import Optional
+
+# error: [invalid-type-form] "`typing.Optional` requires exactly one argument when used in a type expression"
+def f(x: Optional) -> None:
+    reveal_type(x)  # revealed: Unknown
+```

crates/red_knot_python_semantic/resources/mdtest/annotations/union.md

@@ -59,3 +59,13 @@ def f():
     # revealed: int | str
     reveal_type(a)
 ```
+
+## Invalid
+
+```py
+from typing import Union
+
+# error: [invalid-type-form] "`typing.Union` requires at least one argument when used in a type expression"
+def f(x: Union) -> None:
+    reveal_type(x)  # revealed: Unknown
+```

crates/red_knot_python_semantic/resources/mdtest/annotations/unsupported_special_forms.md

@@ -18,7 +18,7 @@ def f(*args: Unpack[Ts]) -> tuple[Unpack[Ts]]:
     # TODO: should understand the annotation
     reveal_type(args)  # revealed: tuple
 
-    reveal_type(Alias)  # revealed: @Todo(Invalid or unsupported `KnownInstanceType` in `Type::to_type_expression`)
+    reveal_type(Alias)  # revealed: @Todo(Support for `typing.TypeAlias`)
 
 def g() -> TypeGuard[int]: ...
 def h() -> TypeIs[int]: ...
@@ -35,7 +35,30 @@ def i(callback: Callable[Concatenate[int, P], R_co], *args: P.args, **kwargs: P.
 
 class Foo:
     def method(self, x: Self):
-        reveal_type(x)  # revealed: @Todo(Invalid or unsupported `KnownInstanceType` in `Type::to_type_expression`)
+        reveal_type(x)  # revealed: @Todo(Support for `typing.Self`)
+```
+
+## Type expressions
+
+One thing that is supported is error messages for using special forms in type expressions.
+
+```py
+from typing_extensions import Unpack, TypeGuard, TypeIs, Concatenate, ParamSpec
+
+def _(
+    a: Unpack,  # error: [invalid-type-form] "`typing.Unpack` requires exactly one argument when used in a type expression"
+    b: TypeGuard,  # error: [invalid-type-form] "`typing.TypeGuard` requires exactly one argument when used in a type expression"
+    c: TypeIs,  # error: [invalid-type-form] "`typing.TypeIs` requires exactly one argument when used in a type expression"
+    d: Concatenate,  # error: [invalid-type-form] "`typing.Concatenate` requires at least two arguments when used in a type expression"
+    e: ParamSpec,
+) -> None:
+    reveal_type(a)  # revealed: Unknown
+    reveal_type(b)  # revealed: Unknown
+    reveal_type(c)  # revealed: Unknown
+    reveal_type(d)  # revealed: Unknown
+
+    def foo(a_: e) -> None:
+        reveal_type(a_)  # revealed: @Todo(Support for `typing.ParamSpec` instances in type expressions)
 ```
 
 ## Inheritance

crates/red_knot_python_semantic/resources/mdtest/annotations/unsupported_type_qualifiers.md

@@ -1,6 +1,6 @@
 # Unsupported type qualifiers
 
-## Not yet supported
+## Not yet fully supported
 
 Several type qualifiers are unsupported by red-knot currently. However, we also don't emit
 false-positive errors if you use one in an annotation:
@@ -19,6 +19,33 @@ class Bar(TypedDict):
     z: ReadOnly[bytes]
 ```
 
+## Type expressions
+
+One thing that is supported is error messages for using type qualifiers in type expressions.
+
+```py
+from typing_extensions import Final, ClassVar, Required, NotRequired, ReadOnly
+
+def _(
+    a: (
+        Final  # error: [invalid-type-form] "Type qualifier `typing.Final` is not allowed in type expressions (only in annotation expressions)"
+        | int
+    ),
+    b: (
+        ClassVar  # error: [invalid-type-form] "Type qualifier `typing.ClassVar` is not allowed in type expressions (only in annotation expressions)"
+        | int
+    ),
+    c: Required,  # error: [invalid-type-form] "Type qualifier `typing.Required` is not allowed in type expressions (only in annotation expressions, and only with exactly one argument)"
+    d: NotRequired,  # error: [invalid-type-form] "Type qualifier `typing.NotRequired` is not allowed in type expressions (only in annotation expressions, and only with exactly one argument)"
+    e: ReadOnly,  # error: [invalid-type-form] "Type qualifier `typing.ReadOnly` is not allowed in type expressions (only in annotation expressions, and only with exactly one argument)"
+) -> None:
+    reveal_type(a)  # revealed: Unknown | int
+    reveal_type(b)  # revealed: Unknown | int
+    reveal_type(c)  # revealed: Unknown
+    reveal_type(d)  # revealed: Unknown
+    reveal_type(e)  # revealed: Unknown
+```
+
 ## Inheritance
 
 You can't inherit from a type qualifier.

crates/red_knot_python_semantic/resources/mdtest/assignment/augmented.md

@@ -10,6 +10,10 @@ reveal_type(x)  # revealed: Literal[2]
 x = 1.0
 x /= 2
 reveal_type(x)  # revealed: int | float
+
+x = (1, 2)
+x += (3, 4)
+reveal_type(x)  # revealed: tuple[Literal[1], Literal[2], Literal[3], Literal[4]]
 ```
 
 ## Dunder methods
@@ -161,3 +165,18 @@ def f(flag: bool, flag2: bool):
 
     reveal_type(f)  # revealed: int | str | float
 ```
+
+## Implicit dunder calls on class objects
+
+```py
+class Meta(type):
+    def __iadd__(cls, other: int) -> str:
+        return ""
+
+class C(metaclass=Meta): ...
+
+cls = C
+cls += 1
+
+reveal_type(cls)  # revealed: str
+```

crates/red_knot_python_semantic/resources/mdtest/attributes.md

@@ -348,8 +348,11 @@ reveal_type(C().y)  # revealed: Unknown | str
 
 ```py
 class ContextManager:
-    def __enter__(self) -> int | None: ...
-    def __exit__(self, exc_type, exc_value, traceback) -> None: ...
+    def __enter__(self) -> int | None:
+        return 1
+
+    def __exit__(self, exc_type, exc_value, traceback) -> None:
+        pass
 
 class C:
     def __init__(self) -> None:
@@ -365,8 +368,11 @@ reveal_type(c_instance.x)  # revealed: Unknown | int | None
 
 ```py
 class ContextManager:
-    def __enter__(self) -> tuple[int | None, int]: ...
-    def __exit__(self, exc_type, exc_value, traceback) -> None: ...
+    def __enter__(self) -> tuple[int | None, int]:
+        return 1, 2
+
+    def __exit__(self, exc_type, exc_value, traceback) -> None:
+        pass
 
 class C:
     def __init__(self) -> None:
@@ -802,7 +808,7 @@ def _(flag1: bool, flag2: bool):
     reveal_type(C5.attr1)  # revealed: Unknown | Literal["metaclass value", "class value"]
 ```
 
-## Union of attributes
+## Unions of attributes
 
 If the (meta)class is a union type or if the attribute on the (meta) class has a union type, we
 infer those union types accordingly:
@@ -812,77 +818,74 @@ def _(flag: bool):
     if flag:
         class C1:
             x = 1
+            y: int = 1
 
     else:
         class C1:
             x = 2
+            y: int | str = "b"
 
     reveal_type(C1.x)  # revealed: Unknown | Literal[1, 2]
+    reveal_type(C1.y)  # revealed: int | str
+
+    C1.y = 100
+    # error: [invalid-assignment] "Object of type `Literal["problematic"]` is not assignable to attribute `y` on type `Literal[C1, C1]`"
+    C1.y = "problematic"
 
     class C2:
         if flag:
             x = 3
+            y: int = 3
         else:
             x = 4
+            y: int | str = "d"
 
     reveal_type(C2.x)  # revealed: Unknown | Literal[3, 4]
+    reveal_type(C2.y)  # revealed: int | str
+
+    C2.y = 100
+    # error: [invalid-assignment] "Object of type `None` is not assignable to attribute `y` of type `int | str`"
+    C2.y = None
+    # TODO: should be an error, needs more sophisticated union handling in `validate_attribute_assignment`
+    C2.y = "problematic"
 
     if flag:
         class Meta3(type):
             x = 5
+            y: int = 5
 
     else:
         class Meta3(type):
             x = 6
+            y: int | str = "f"
 
     class C3(metaclass=Meta3): ...
     reveal_type(C3.x)  # revealed: Unknown | Literal[5, 6]
+    reveal_type(C3.y)  # revealed: int | str
+
+    C3.y = 100
+    # error: [invalid-assignment] "Object of type `None` is not assignable to attribute `y` of type `int | str`"
+    C3.y = None
+    # TODO: should be an error, needs more sophisticated union handling in `validate_attribute_assignment`
+    C3.y = "problematic"
 
     class Meta4(type):
         if flag:
             x = 7
+            y: int = 7
         else:
             x = 8
+            y: int | str = "h"
 
     class C4(metaclass=Meta4): ...
     reveal_type(C4.x)  # revealed: Unknown | Literal[7, 8]
-```
+    reveal_type(C4.y)  # revealed: int | str
 
-## Inherited class attributes
-
-### Basic
-
-```py
-class A:
-    X = "foo"
-
-class B(A): ...
-class C(B): ...
-
-reveal_type(C.X)  # revealed: Unknown | Literal["foo"]
-```
-
-### Multiple inheritance
-
-```py
-class O: ...
-
-class F(O):
-    X = 56
-
-class E(O):
-    X = 42
-
-class D(O): ...
-class C(D, F): ...
-class B(E, D): ...
-class A(B, C): ...
-
-# revealed: tuple[Literal[A], Literal[B], Literal[E], Literal[C], Literal[D], Literal[F], Literal[O], Literal[object]]
-reveal_type(A.__mro__)
-
-# `E` is earlier in the MRO than `F`, so we should use the type of `E.X`
-reveal_type(A.X)  # revealed: Unknown | Literal[42]
+    C4.y = 100
+    # error: [invalid-assignment] "Object of type `None` is not assignable to attribute `y` of type `int | str`"
+    C4.y = None
+    # TODO: should be an error, needs more sophisticated union handling in `validate_attribute_assignment`
+    C4.y = "problematic"
 ```
 
 ## Unions with possibly unbound paths
@@ -906,8 +909,14 @@ def _(flag1: bool, flag2: bool):
     # error: [possibly-unbound-attribute] "Attribute `x` on type `Literal[C1, C2, C3]` is possibly unbound"
     reveal_type(C.x)  # revealed: Unknown | Literal[1, 3]
 
+    # error: [invalid-assignment] "Object of type `Literal[100]` is not assignable to attribute `x` on type `Literal[C1, C2, C3]`"
+    C.x = 100
+
     # error: [possibly-unbound-attribute] "Attribute `x` on type `C1 | C2 | C3` is possibly unbound"
     reveal_type(C().x)  # revealed: Unknown | Literal[1, 3]
+
+    # error: [invalid-assignment] "Object of type `Literal[100]` is not assignable to attribute `x` on type `C1 | C2 | C3`"
+    C().x = 100
 ```
 
 ### Possibly-unbound within a class
@@ -932,10 +941,16 @@ def _(flag: bool, flag1: bool, flag2: bool):
     # error: [possibly-unbound-attribute] "Attribute `x` on type `Literal[C1, C2, C3]` is possibly unbound"
     reveal_type(C.x)  # revealed: Unknown | Literal[1, 2, 3]
 
+    # error: [possibly-unbound-attribute]
+    C.x = 100
+
     # Note: we might want to consider ignoring possibly-unbound diagnostics for instance attributes eventually,
     # see the "Possibly unbound/undeclared instance attribute" section below.
     # error: [possibly-unbound-attribute] "Attribute `x` on type `C1 | C2 | C3` is possibly unbound"
     reveal_type(C().x)  # revealed: Unknown | Literal[1, 2, 3]
+
+    # error: [possibly-unbound-attribute]
+    C().x = 100
 ```
 
 ### Possibly-unbound within gradual types
@@ -953,6 +968,9 @@ def _(flag: bool):
             x: int
 
     reveal_type(Derived().x)  # revealed: int | Any
+
+    Derived().x = 1
+    Derived().x = "a"
 ```
 
 ### Attribute possibly unbound on a subclass but not on a superclass
@@ -967,8 +985,10 @@ def _(flag: bool):
             x = 2
 
     reveal_type(Bar.x)  # revealed: Unknown | Literal[2, 1]
+    Bar.x = 3
 
     reveal_type(Bar().x)  # revealed: Unknown | Literal[2, 1]
+    Bar().x = 3
 ```
 
 ### Attribute possibly unbound on a subclass and on a superclass
@@ -986,8 +1006,14 @@ def _(flag: bool):
     # error: [possibly-unbound-attribute]
     reveal_type(Bar.x)  # revealed: Unknown | Literal[2, 1]
 
+    # error: [possibly-unbound-attribute]
+    Bar.x = 3
+
     # error: [possibly-unbound-attribute]
     reveal_type(Bar().x)  # revealed: Unknown | Literal[2, 1]
+
+    # error: [possibly-unbound-attribute]
+    Bar().x = 3
 ```
 
 ### Possibly unbound/undeclared instance attribute
@@ -1006,6 +1032,9 @@ def _(flag: bool):
 
     # error: [possibly-unbound-attribute]
     reveal_type(Foo().x)  # revealed: int | Unknown
+
+    # error: [possibly-unbound-attribute]
+    Foo().x = 1
 ```
 
 #### Possibly unbound
@@ -1020,9 +1049,229 @@ def _(flag: bool):
     # Emitting a diagnostic in a case like this is not something we support, and it's unclear
     # if we ever will (or want to)
     reveal_type(Foo().x)  # revealed: Unknown | Literal[1]
+
+    # Same here
+    Foo().x = 2
 ```
 
-### Attribute access on `Any`
+### Unions with all paths unbound
+
+If the symbol is unbound in all elements of the union, we detect that:
+
+```py
+def _(flag: bool):
+    class C1: ...
+    class C2: ...
+    C = C1 if flag else C2
+
+    # error: [unresolved-attribute] "Type `Literal[C1, C2]` has no attribute `x`"
+    reveal_type(C.x)  # revealed: Unknown
+
+    # TODO: This should ideally be a `unresolved-attribute` error. We need better union
+    # handling in `validate_attribute_assignment` for this.
+    # error: [invalid-assignment] "Object of type `Literal[1]` is not assignable to attribute `x` on type `Literal[C1, C2]`"
+    C.x = 1
+```
+
+## Inherited class attributes
+
+### Basic
+
+```py
+class A:
+    X = "foo"
+
+class B(A): ...
+class C(B): ...
+
+reveal_type(C.X)  # revealed: Unknown | Literal["foo"]
+
+C.X = "bar"
+```
+
+### Multiple inheritance
+
+```py
+class O: ...
+
+class F(O):
+    X = 56
+
+class E(O):
+    X = 42
+
+class D(O): ...
+class C(D, F): ...
+class B(E, D): ...
+class A(B, C): ...
+
+# revealed: tuple[Literal[A], Literal[B], Literal[E], Literal[C], Literal[D], Literal[F], Literal[O], Literal[object]]
+reveal_type(A.__mro__)
+
+# `E` is earlier in the MRO than `F`, so we should use the type of `E.X`
+reveal_type(A.X)  # revealed: Unknown | Literal[42]
+
+A.X = 100
+```
+
+## Intersections of attributes
+
+### Attribute only available on one element
+
+```py
+from knot_extensions import Intersection
+
+class A:
+    x: int = 1
+
+class B: ...
+
+def _(a_and_b: Intersection[A, B]):
+    reveal_type(a_and_b.x)  # revealed: int
+
+    a_and_b.x = 2
+
+# Same for class objects
+def _(a_and_b: Intersection[type[A], type[B]]):
+    reveal_type(a_and_b.x)  # revealed: int
+
+    a_and_b.x = 2
+```
+
+### Attribute available on both elements
+
+```py
+from knot_extensions import Intersection
+
+class P: ...
+class Q: ...
+class R(P, Q): ...
+
+class A:
+    x: P = P()
+
+class B:
+    x: Q = Q()
+
+def _(a_and_b: Intersection[A, B]):
+    reveal_type(a_and_b.x)  # revealed: P & Q
+    a_and_b.x = R()
+
+# Same for class objects
+def _(a_and_b: Intersection[type[A], type[B]]):
+    reveal_type(a_and_b.x)  # revealed: P & Q
+    a_and_b.x = R()
+```
+
+### Possible unboundness
+
+```py
+from knot_extensions import Intersection
+
+class P: ...
+class Q: ...
+class R(P, Q): ...
+
+def _(flag: bool):
+    class A1:
+        if flag:
+            x: P = P()
+
+    class B1: ...
+
+    def inner1(a_and_b: Intersection[A1, B1]):
+        # error: [possibly-unbound-attribute]
+        reveal_type(a_and_b.x)  # revealed: P
+
+        # error: [possibly-unbound-attribute]
+        a_and_b.x = R()
+    # Same for class objects
+    def inner1_class(a_and_b: Intersection[type[A1], type[B1]]):
+        # error: [possibly-unbound-attribute]
+        reveal_type(a_and_b.x)  # revealed: P
+
+        # error: [possibly-unbound-attribute]
+        a_and_b.x = R()
+
+    class A2:
+        if flag:
+            x: P = P()
+
+    class B1:
+        x: Q = Q()
+
+    def inner2(a_and_b: Intersection[A2, B1]):
+        reveal_type(a_and_b.x)  # revealed: P & Q
+
+        # TODO: this should not be an error, we need better intersection
+        # handling in `validate_attribute_assignment` for this
+        # error: [possibly-unbound-attribute]
+        a_and_b.x = R()
+    # Same for class objects
+    def inner2_class(a_and_b: Intersection[type[A2], type[B1]]):
+        reveal_type(a_and_b.x)  # revealed: P & Q
+
+    class A3:
+        if flag:
+            x: P = P()
+
+    class B3:
+        if flag:
+            x: Q = Q()
+
+    def inner3(a_and_b: Intersection[A3, B3]):
+        # error: [possibly-unbound-attribute]
+        reveal_type(a_and_b.x)  # revealed: P & Q
+
+        # error: [possibly-unbound-attribute]
+        a_and_b.x = R()
+    # Same for class objects
+    def inner3_class(a_and_b: Intersection[type[A3], type[B3]]):
+        # error: [possibly-unbound-attribute]
+        reveal_type(a_and_b.x)  # revealed: P & Q
+
+        # error: [possibly-unbound-attribute]
+        a_and_b.x = R()
+
+    class A4: ...
+    class B4: ...
+
+    def inner4(a_and_b: Intersection[A4, B4]):
+        # error: [unresolved-attribute]
+        reveal_type(a_and_b.x)  # revealed: Unknown
+
+        # error: [invalid-assignment]
+        a_and_b.x = R()
+    # Same for class objects
+    def inner4_class(a_and_b: Intersection[type[A4], type[B4]]):
+        # error: [unresolved-attribute]
+        reveal_type(a_and_b.x)  # revealed: Unknown
+
+        # error: [invalid-assignment]
+        a_and_b.x = R()
+```
+
+### Intersection of implicit instance attributes
+
+```py
+from knot_extensions import Intersection
+
+class P: ...
+class Q: ...
+
+class A:
+    def __init__(self):
+        self.x: P = P()
+
+class B:
+    def __init__(self):
+        self.x: Q = Q()
+
+def _(a_and_b: Intersection[A, B]):
+    reveal_type(a_and_b.x)  # revealed: P & Q
+```
+
+## Attribute access on `Any`
 
 The union of the set of types that `Any` could materialise to is equivalent to `object`. It follows
 from this that attribute access on `Any` resolves to `Any` if the attribute does not exist on
@@ -1053,18 +1302,96 @@ reveal_type(C.__mro__)  # revealed: tuple[Literal[C], Literal[B], Any, Literal[A
 reveal_type(C.x)  # revealed: Literal[1] & Any
 ```
 
-### Unions with all paths unbound
+## Classes with custom `__getattr__` methods
 
-If the symbol is unbound in all elements of the union, we detect that:
+### Basic
+
+If a type provides a custom `__getattr__` method, we use the return type of that method as the type
+for unknown attributes. Consider the following `CustomGetAttr` class:
 
 ```py
-def _(flag: bool):
-    class C1: ...
-    class C2: ...
-    C = C1 if flag else C2
+from typing import Literal
 
-    # error: [unresolved-attribute] "Type `Literal[C1, C2]` has no attribute `x`"
-    reveal_type(C.x)  # revealed: Unknown
+def flag() -> bool:
+    return True
+
+class GetAttrReturnType: ...
+
+class CustomGetAttr:
+    class_attr: int = 1
+
+    if flag():
+        possibly_unbound: bytes = b"a"
+
+    def __init__(self) -> None:
+        self.instance_attr: str = "a"
+
+    def __getattr__(self, name: str) -> GetAttrReturnType:
+        return GetAttrReturnType()
+```
+
+We can access arbitrary attributes on instances of this class, and the type of the attribute will be
+`GetAttrReturnType`:
+
+```py
+c = CustomGetAttr()
+
+reveal_type(c.whatever)  # revealed: GetAttrReturnType
+```
+
+If an attribute is defined on the class, it takes precedence over the `__getattr__` method:
+
+```py
+reveal_type(c.class_attr)  # revealed: int
+```
+
+If the class attribute is possibly unbound, we union the type of the attribute with the fallback
+type of the `__getattr__` method:
+
+```py
+reveal_type(c.possibly_unbound)  # revealed: bytes | GetAttrReturnType
+```
+
+Instance attributes also take precedence over the `__getattr__` method:
+
+```py
+# Note: we could attempt to union with the fallback type of `__getattr__` here, as we currently do not
+# attempt to determine if instance attributes are always bound or not. Neither mypy nor pyright do this,
+# so it's not a priority.
+reveal_type(c.instance_attr)  # revealed: str
+```
+
+### Type of the `name` parameter
+
+If the `name` parameter of the `__getattr__` method is annotated with a (union of) literal type(s),
+we only consider the attribute access to be valid if the accessed attribute is one of them:
+
+```py
+from typing import Literal
+
+class Date:
+    def __getattr__(self, name: Literal["day", "month", "year"]) -> int:
+        return 0
+
+date = Date()
+
+reveal_type(date.day)  # revealed: int
+reveal_type(date.month)  # revealed: int
+reveal_type(date.year)  # revealed: int
+
+# error: [unresolved-attribute] "Type `Date` has no attribute `century`"
+reveal_type(date.century)  # revealed: Unknown
+```
+
+### `argparse.Namespace`
+
+A standard library example of a class with a custom `__getattr__` method is `argparse.Namespace`:
+
+```py
+import argparse
+
+def _(ns: argparse.Namespace):
+    reveal_type(ns.whatever)  # revealed: Any
 ```
 
 ## Objects of all types have a `__class__` method
@@ -1119,6 +1446,8 @@ reveal_type(Foo.__class__)  # revealed: Literal[type]
 
 ## Module attributes
 
+### Basic
+
 `mod.py`:
 
 ```py
@@ -1153,7 +1482,7 @@ for mod.global_symbol in IntIterable():
     pass
 ```
 
-## Nested attributes
+### Nested module attributes
 
 `outer/__init__.py`:
 

crates/red_knot_python_semantic/resources/mdtest/binary/instances.md

@@ -363,7 +363,7 @@ reveal_type(X() + Y())  # revealed: int
 
 ```py
 class NotBoolable:
-    __bool__ = 3
+    __bool__: int = 3
 
 a = NotBoolable()
 
@@ -406,10 +406,12 @@ A left-hand dunder method doesn't apply for the right-hand operand, or vice vers
 
 ```py
 class A:
-    def __add__(self, other) -> int: ...
+    def __add__(self, other) -> int:
+        return 1
 
 class B:
-    def __radd__(self, other) -> int: ...
+    def __radd__(self, other) -> int:
+        return 1
 
 class C: ...
 

crates/red_knot_python_semantic/resources/mdtest/binary/tuples.md

@@ -0,0 +1,22 @@
+# Binary operations on tuples
+
+## Concatenation for heterogeneous tuples
+
+```py
+reveal_type((1, 2) + (3, 4))  # revealed: tuple[Literal[1], Literal[2], Literal[3], Literal[4]]
+reveal_type(() + (1, 2))  # revealed: tuple[Literal[1], Literal[2]]
+reveal_type((1, 2) + ())  # revealed: tuple[Literal[1], Literal[2]]
+reveal_type(() + ())  # revealed: tuple[()]
+
+def _(x: tuple[int, str], y: tuple[None, tuple[int]]):
+    reveal_type(x + y)  # revealed: tuple[int, str, None, tuple[int]]
+    reveal_type(y + x)  # revealed: tuple[None, tuple[int], int, str]
+```
+
+## Concatenation for homogeneous tuples
+
+```py
+def _(x: tuple[int, ...], y: tuple[str, ...]):
+    reveal_type(x + y)  # revealed: @Todo(full tuple[...] support)
+    reveal_type(x + (1, 2))  # revealed: @Todo(full tuple[...] support)
+```

crates/red_knot_python_semantic/resources/mdtest/binary/unions.md

@@ -0,0 +1,51 @@
+# Binary operations on union types
+
+Binary operations on union types are only available if they are supported for all possible
+combinations of types:
+
+```py
+def f1(i: int, u: int | None):
+    # error: [unsupported-operator] "Operator `+` is unsupported between objects of type `int` and `int | None`"
+    reveal_type(i + u)  # revealed: Unknown
+    # error: [unsupported-operator] "Operator `+` is unsupported between objects of type `int | None` and `int`"
+    reveal_type(u + i)  # revealed: Unknown
+```
+
+`int` can be added to `int`, and `str` can be added to `str`, but expressions of type `int | str`
+cannot be added, because that would require addition of `int` and `str` or vice versa:
+
+```py
+def f2(i: int, s: str, int_or_str: int | str):
+    i + i
+    s + s
+    # error: [unsupported-operator] "Operator `+` is unsupported between objects of type `int | str` and `int | str`"
+    reveal_type(int_or_str + int_or_str)  # revealed: Unknown
+```
+
+However, if an operation is supported for all possible combinations, the result will be a union of
+the possible outcomes:
+
+```py
+from typing import Literal
+
+def f3(two_or_three: Literal[2, 3], a_or_b: Literal["a", "b"]):
+    reveal_type(two_or_three + two_or_three)  # revealed: Literal[4, 5, 6]
+    reveal_type(two_or_three**two_or_three)  # revealed: Literal[4, 8, 9, 27]
+
+    reveal_type(a_or_b + a_or_b)  # revealed: Literal["aa", "ab", "ba", "bb"]
+
+    reveal_type(two_or_three * a_or_b)  # revealed: Literal["aa", "bb", "aaa", "bbb"]
+```
+
+We treat a type annotation of `float` as a union of `int` and `float`, so union handling is relevant
+here:
+
+```py
+def f4(x: float, y: float):
+    reveal_type(x + y)  # revealed: int | float
+    reveal_type(x - y)  # revealed: int | float
+    reveal_type(x * y)  # revealed: int | float
+    reveal_type(x / y)  # revealed: int | float
+    reveal_type(x // y)  # revealed: int | float
+    reveal_type(x % y)  # revealed: int | float
+```

crates/red_knot_python_semantic/resources/mdtest/boundness_declaredness/public.md

@@ -69,7 +69,8 @@ without raising an error.
 from typing import Any
 
 def any() -> Any: ...
-def flag() -> bool: ...
+def flag() -> bool:
+    return True
 
 a: int
 b: str
@@ -126,7 +127,8 @@ inferred types:
 from typing import Any
 
 def any() -> Any: ...
-def flag() -> bool: ...
+def flag() -> bool:
+    return True
 
 a = 1
 b = 2
@@ -164,7 +166,8 @@ error for both `a` and `b`:
 ```py
 from typing import Any
 
-def flag() -> bool: ...
+def flag() -> bool:
+    return True
 
 if flag():
     a: Any = 1
@@ -194,7 +197,8 @@ seems inconsistent when compared to the case just above.
 `mod.py`:
 
 ```py
-def flag() -> bool: ...
+def flag() -> bool:
+    return True
 
 if flag():
     a: int
@@ -248,7 +252,8 @@ inconsistent when compared to the "possibly-undeclared-and-possibly-unbound" cas
 `mod.py`:
 
 ```py
-def flag() -> bool: ...
+def flag() -> bool:
+    return True
 
 if flag:
     a = 1

crates/red_knot_python_semantic/resources/mdtest/call/builtins.md

@@ -6,7 +6,7 @@
 class NotBool:
     __bool__ = None
 
-# TODO: We should emit an `invalid-argument` error here for `2` because `bool` only takes one argument.
+# error: [too-many-positional-arguments] "Too many positional arguments to class `bool`: expected 1, got 2"
 bool(1, 2)
 
 # TODO: We should emit an `unsupported-bool-conversion` error here because the argument doesn't implement `__bool__` correctly.
@@ -29,9 +29,12 @@ But a three-argument call to type creates a dynamic instance of the `type` class
 reveal_type(type("Foo", (), {}))  # revealed: type
 ```
 
-Other numbers of arguments are invalid (TODO -- these should emit a diagnostic)
+Other numbers of arguments are invalid
 
 ```py
+# error: [no-matching-overload] "No overload of class `type` matches arguments"
 type("Foo", ())
+
+# error: [no-matching-overload] "No overload of class `type` matches arguments"
 type("Foo", (), {}, weird_other_arg=42)
 ```

crates/red_knot_python_semantic/resources/mdtest/call/callable_instance.md

@@ -25,7 +25,8 @@ reveal_type(b)  # revealed: Unknown
 def _(flag: bool):
     class PossiblyNotCallable:
         if flag:
-            def __call__(self) -> int: ...
+            def __call__(self) -> int:
+                return 1
 
     a = PossiblyNotCallable()
     result = a()  # error: "Object of type `PossiblyNotCallable` is not callable (possibly unbound `__call__` method)"
@@ -38,7 +39,8 @@ def _(flag: bool):
 def _(flag: bool):
     if flag:
         class PossiblyUnbound:
-            def __call__(self) -> int: ...
+            def __call__(self) -> int:
+                return 1
 
     # error: [possibly-unresolved-reference]
     a = PossiblyUnbound()
@@ -64,11 +66,12 @@ def _(flag: bool):
         if flag:
             __call__ = 1
         else:
-            def __call__(self) -> int: ...
+            def __call__(self) -> int:
+                return 1
 
     a = NonCallable()
     # error: [call-non-callable] "Object of type `Literal[1]` is not callable"
-    reveal_type(a())  # revealed: int | Unknown
+    reveal_type(a())  # revealed: Unknown | int
 ```
 
 ## Call binding errors

crates/red_knot_python_semantic/resources/mdtest/call/dunder.md

@@ -185,7 +185,7 @@ def _(flag: bool):
                 return str(key)
         else:
             def __getitem__(self, key: int) -> bytes:
-                return key
+                return bytes()
 
     c = C()
     reveal_type(c[0])  # revealed: str | bytes
@@ -198,7 +198,7 @@ def _(flag: bool):
     else:
         class D:
             def __getitem__(self, key: int) -> bytes:
-                return key
+                return bytes()
 
     d = D()
     reveal_type(d[0])  # revealed: str | bytes

crates/red_knot_python_semantic/resources/mdtest/call/function.md

@@ -37,6 +37,8 @@ def foo() -> int:
     return 42
 
 def decorator(func) -> Callable[[], int]:
+    # TODO: no error
+    # error: [invalid-return-type]
     return foo
 
 @decorator

crates/red_knot_python_semantic/resources/mdtest/call/methods.md

@@ -235,23 +235,23 @@ method_wrapper(C(), None)
 method_wrapper(None, C)
 
 # Passing `None` without an `owner` argument is an
-# error: [missing-argument] "No argument provided for required parameter `owner`"
+# error: [no-matching-overload] "No overload of method wrapper `__get__` of function `f` matches arguments"
 method_wrapper(None)
 
 # Passing something that is not assignable to `type` as the `owner` argument is an
-# error: [invalid-argument-type] "Object of type `Literal[1]` cannot be assigned to parameter 2 (`owner`) of method wrapper `__get__` of function `f`; expected type `type`"
+# error: [no-matching-overload] "No overload of method wrapper `__get__` of function `f` matches arguments"
 method_wrapper(None, 1)
 
 # Passing `None` as the `owner` argument when `instance` is `None` is an
-# error: [invalid-argument-type] "Object of type `None` cannot be assigned to parameter 2 (`owner`) of method wrapper `__get__` of function `f`; expected type `type`"
+# error: [no-matching-overload] "No overload of method wrapper `__get__` of function `f` matches arguments"
 method_wrapper(None, None)
 
 # Calling `__get__` without any arguments is an
-# error: [missing-argument] "No argument provided for required parameter `instance`"
+# error: [no-matching-overload] "No overload of method wrapper `__get__` of function `f` matches arguments"
 method_wrapper()
 
 # Calling `__get__` with too many positional arguments is an
-# error: [too-many-positional-arguments] "Too many positional arguments to method wrapper `__get__` of function `f`: expected 2, got 3"
+# error: [no-matching-overload] "No overload of method wrapper `__get__` of function `f` matches arguments"
 method_wrapper(C(), C, "one too many")
 ```
 

crates/red_knot_python_semantic/resources/mdtest/call/union.md

@@ -40,7 +40,7 @@ def _(flag: bool):
         def f() -> int:
             return 1
     x = f()  # error: [call-non-callable] "Object of type `Literal[1]` is not callable"
-    reveal_type(x)  # revealed: int | Unknown
+    reveal_type(x)  # revealed: Unknown | int
 ```
 
 ## Multiple non-callable elements in a union
@@ -58,7 +58,7 @@ def _(flag: bool, flag2: bool):
             return 1
     # TODO we should mention all non-callable elements of the union
     # error: [call-non-callable] "Object of type `Literal[1]` is not callable"
-    # revealed: int | Unknown
+    # revealed: Unknown | int
     reveal_type(f())
 ```
 
@@ -82,8 +82,12 @@ def _(flag: bool):
 Calling a union where the arguments don't match the signature of all variants.
 
 ```py
-def f1(a: int) -> int: ...
-def f2(a: str) -> str: ...
+def f1(a: int) -> int:
+    return a
+
+def f2(a: str) -> str:
+    return a
+
 def _(flag: bool):
     if flag:
         f = f1
@@ -144,3 +148,16 @@ def _(flag: bool):
     x = f(3)
     reveal_type(x)  # revealed: Unknown
 ```
+
+## Union including a special-cased function
+
+```py
+def _(flag: bool):
+    if flag:
+        f = str
+    else:
+        f = repr
+    reveal_type(str("string"))  # revealed: Literal["string"]
+    reveal_type(repr("string"))  # revealed: Literal["'string'"]
+    reveal_type(f("string"))  # revealed: Literal["string", "'string'"]
+```

crates/red_knot_python_semantic/resources/mdtest/comparison/instances/membership_test.md

@@ -191,7 +191,7 @@ It may also be more appropriate to use `unsupported-operator` as the error code.
 
 ```py
 class NotBoolable:
-    __bool__ = 3
+    __bool__: int = 3
 
 class WithContains:
     def __contains__(self, item) -> NotBoolable:

crates/red_knot_python_semantic/resources/mdtest/comparison/instances/rich_comparison.md

@@ -154,7 +154,7 @@ reveal_type(B() >= A())  # revealed: LeReturnType
 
 class C:
     def __gt__(self, other: C) -> EqReturnType:
-        return 42
+        return EqReturnType()
 
     def __ge__(self, other: C) -> NeReturnType:
         return NeReturnType()
@@ -355,7 +355,7 @@ element) of a chained comparison.
 
 ```py
 class NotBoolable:
-    __bool__ = 3
+    __bool__: int = 3
 
 class Comparable:
     def __lt__(self, item) -> NotBoolable:

crates/red_knot_python_semantic/resources/mdtest/comparison/intersections.md

@@ -110,7 +110,8 @@ given operator:
 
 ```py
 class Container:
-    def __contains__(self, x) -> bool: ...
+    def __contains__(self, x) -> bool:
+        return False
 
 class NonContainer: ...
 
@@ -130,7 +131,8 @@ unsupported for the given operator:
 
 ```py
 class Container:
-    def __contains__(self, x) -> bool: ...
+    def __contains__(self, x) -> bool:
+        return False
 
 class NonContainer: ...
 

crates/red_knot_python_semantic/resources/mdtest/comparison/non_bool_returns.md

@@ -22,14 +22,19 @@ Walking through examples:
 from __future__ import annotations
 
 class A:
-    def __lt__(self, other) -> A: ...
-    def __gt__(self, other) -> bool: ...
+    def __lt__(self, other) -> A:
+        return self
+
+    def __gt__(self, other) -> bool:
+        return False
 
 class B:
-    def __lt__(self, other) -> B: ...
+    def __lt__(self, other) -> B:
+        return self
 
 class C:
-    def __lt__(self, other) -> C: ...
+    def __lt__(self, other) -> C:
+        return self
 
 x = A() < B() < C()
 reveal_type(x)  # revealed: A & ~AlwaysTruthy | B

crates/red_knot_python_semantic/resources/mdtest/comparison/tuples.md

@@ -197,7 +197,7 @@ class LtReturnTypeOnB: ...
 
 class B:
     def __lt__(self, o: B) -> LtReturnTypeOnB:
-        return set()
+        return LtReturnTypeOnB()
 
 reveal_type((A(), B()) < (A(), B()))  # revealed: LtReturnType | LtReturnTypeOnB | Literal[False]
 ```
@@ -355,7 +355,7 @@ def compute_chained_comparison():
 
 ```py
 class NotBoolable:
-    __bool__ = 5
+    __bool__: int = 5
 
 class Comparable:
     def __lt__(self, other) -> NotBoolable:
@@ -387,7 +387,7 @@ class A:
         return NotBoolable()
 
 class NotBoolable:
-    __bool__ = None
+    __bool__: None = None
 
 # error: [unsupported-bool-conversion]
 (A(),) == (A(),)

crates/red_knot_python_semantic/resources/mdtest/comprehensions/basic.md

@@ -104,7 +104,8 @@ class Iterator:
         return 42
 
 class Iterable:
-    def __iter__(self) -> Iterator: ...
+    def __iter__(self) -> Iterator:
+        return Iterator()
 
 # This is fine:
 x = [*Iterable()]

crates/red_knot_python_semantic/resources/mdtest/conditional/if_expression.md

@@ -40,7 +40,7 @@ def _(flag: bool):
 
 ```py
 class NotBoolable:
-    __bool__ = 3
+    __bool__: int = 3
 
 # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
 3 if NotBoolable() else 4

crates/red_knot_python_semantic/resources/mdtest/conditional/if_statement.md

@@ -152,7 +152,7 @@ def _(flag: bool):
 
 ```py
 class NotBoolable:
-    __bool__ = 3
+    __bool__: int = 3
 
 # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
 if NotBoolable():

crates/red_knot_python_semantic/resources/mdtest/conditional/match.md

@@ -48,7 +48,7 @@ def _(target: int):
 
 ```py
 class NotBoolable:
-    __bool__ = 3
+    __bool__: int = 3
 
 def _(target: int, flag: NotBoolable):
     y = 1

crates/red_knot_python_semantic/resources/mdtest/descriptor_protocol.md

@@ -6,7 +6,9 @@ A descriptor is an attribute value that has one of the methods in the descriptor
 methods are `__get__()`, `__set__()`, and `__delete__()`. If any of those methods are defined for an
 attribute, it is said to be a descriptor.
 
-## Basic example
+## Basic properties
+
+### Example
 
 An introductory example, modeled after a [simple example] in the primer on descriptors, involving a
 descriptor that returns a constant value:
@@ -30,18 +32,26 @@ reveal_type(c.ten)  # revealed: Literal[10]
 
 reveal_type(C.ten)  # revealed: Literal[10]
 
-# These are fine:
+# This is fine:
 c.ten = 10
-C.ten = 10
 
-# error: [invalid-assignment] "Object of type `Literal[11]` is not assignable to attribute `ten` of type `Literal[10]`"
+# error: [invalid-assignment] "Invalid assignment to data descriptor attribute `ten` on type `C` with custom `__set__` method"
 c.ten = 11
+```
 
-# error: [invalid-assignment] "Object of type `Literal[11]` is not assignable to attribute `ten` of type `Literal[10]`"
+When assigning to the `ten` attribute from the class object, we get an error. The descriptor
+protocol is *not* triggered in this case. Since the attribute is declared as `Ten` in the class
+body, we do not allow these assignments, preventing users from accidentally overwriting the data
+descriptor, which is what would happen at runtime:
+
+```py
+# error: [invalid-assignment] "Object of type `Literal[10]` is not assignable to attribute `ten` of type `Ten`"
+C.ten = 10
+# error: [invalid-assignment] "Object of type `Literal[11]` is not assignable to attribute `ten` of type `Ten`"
 C.ten = 11
 ```
 
-## Different types for `__get__` and `__set__`
+### Different types for `__get__` and `__set__`
 
 The return type of `__get__` and the value type of `__set__` can be different:
 
@@ -64,19 +74,17 @@ c = C()
 reveal_type(c.flexible_int)  # revealed: int | None
 
 c.flexible_int = 42  # okay
-# TODO: This should not be an error
-# error: [invalid-assignment]
 c.flexible_int = "42"  # also okay!
 
 reveal_type(c.flexible_int)  # revealed: int | None
 
-# TODO: This should be an error
+# error: [invalid-assignment] "Invalid assignment to data descriptor attribute `flexible_int` on type `C` with custom `__set__` method"
 c.flexible_int = None  # not okay
 
 reveal_type(c.flexible_int)  # revealed: int | None
 ```
 
-## Data and non-data descriptors
+### Data and non-data descriptors
 
 Descriptors that define `__set__` or `__delete__` are called *data descriptors*. An example of a
 data descriptor is a `property` with a setter and/or a deleter. Descriptors that only define
@@ -131,6 +139,84 @@ reveal_type(C.non_data_descriptor)  # revealed: Unknown | Literal["non-data"]
 C.data_descriptor = "something else"  # This is okay
 ```
 
+### Partial fall back
+
+Our implementation of the descriptor protocol takes into account that symbols can be possibly
+unbound. In those cases, we fall back to lower precedence steps of the descriptor protocol and union
+all possible results accordingly. We start by defining a data and a non-data descriptor:
+
+```py
+from typing import Literal
+
+class DataDescriptor:
+    def __get__(self, instance: object, owner: type | None = None) -> Literal["data"]:
+        return "data"
+
+    def __set__(self, instance: object, value: int) -> None:
+        pass
+
+class NonDataDescriptor:
+    def __get__(self, instance: object, owner: type | None = None) -> Literal["non-data"]:
+        return "non-data"
+```
+
+Then, we demonstrate that we fall back to an instance attribute if a data descriptor is possibly
+unbound:
+
+```py
+def f1(flag: bool):
+    class C1:
+        if flag:
+            attr = DataDescriptor()
+
+        def f(self):
+            self.attr = "normal"
+
+    reveal_type(C1().attr)  # revealed: Unknown | Literal["data", "normal"]
+
+    # Assigning to the attribute also causes no `possibly-unbound` diagnostic:
+    C1().attr = 1
+```
+
+We never treat implicit instance attributes as definitely bound, so we fall back to the non-data
+descriptor here:
+
+```py
+class C2:
+    def f(self):
+        self.attr = "normal"
+    attr = NonDataDescriptor()
+
+reveal_type(C2().attr)  # revealed: Unknown | Literal["non-data", "normal"]
+
+# Assignments always go to the instance attribute in this case
+C2().attr = 1
+```
+
+### Descriptors only work when used as class variables
+
+Descriptors only work when used as class variables. When put in instances, they have no effect.
+
+```py
+from typing import Literal
+
+class Ten:
+    def __get__(self, instance: object, owner: type | None = None) -> Literal[10]:
+        return 10
+
+class C:
+    def __init__(self):
+        self.ten: Ten = Ten()
+
+reveal_type(C().ten)  # revealed: Ten
+
+C().ten = Ten()
+
+# The instance attribute is declared as `Ten`, so this is an
+# error: [invalid-assignment] "Object of type `Literal[10]` is not assignable to attribute `ten` of type `Ten`"
+C().ten = 10
+```
+
 ## Descriptor protocol for class objects
 
 When attributes are accessed on a class object, the following [precedence chain] is used:
@@ -150,7 +236,7 @@ class DataDescriptor:
     def __get__(self, instance: object, owner: type | None = None) -> Literal["data"]:
         return "data"
 
-    def __set__(self, instance: object, value: str) -> None:
+    def __set__(self, instance: object, value: int) -> None:
         pass
 
 class NonDataDescriptor:
@@ -177,7 +263,28 @@ reveal_type(C1.class_data_descriptor)  # revealed: Literal["data"]
 reveal_type(C1.class_non_data_descriptor)  # revealed: Literal["non-data"]
 ```
 
-Next, we demonstrate that a *metaclass data descriptor* takes precedence over all class-level
+Assignments to class object attribute only trigger the descriptor protocol if the data descriptor is
+on the metaclass:
+
+```py
+C1.meta_data_descriptor = 1
+
+# error: [invalid-assignment] "Invalid assignment to data descriptor attribute `meta_data_descriptor` on type `Literal[C1]` with custom `__set__` method"
+C1.meta_data_descriptor = "invalid"
+```
+
+When writing to a class-level data descriptor from the class object itself, the descriptor protocol
+is *not* triggered (this is in contrast to what happens when you read class-level descriptor
+attributes!). So the following assignment does not call `__set__`. At runtime, the assignment would
+overwrite the data descriptor, but the attribute is declared as `DataDescriptor` in the class body,
+so we do not allow this:
+
+```py
+# error: [invalid-assignment] "Object of type `Literal[1]` is not assignable to attribute `class_data_descriptor` of type `DataDescriptor`"
+C1.class_data_descriptor = 1
+```
+
+We now demonstrate that a *metaclass data descriptor* takes precedence over all class-level
 attributes:
 
 ```py
@@ -198,6 +305,14 @@ class C2(metaclass=Meta2):
 
 reveal_type(C2.meta_data_descriptor1)  # revealed: Literal["data"]
 reveal_type(C2.meta_data_descriptor2)  # revealed: Literal["data"]
+
+C2.meta_data_descriptor1 = 1
+C2.meta_data_descriptor2 = 1
+
+# error: [invalid-assignment]
+C2.meta_data_descriptor1 = "invalid"
+# error: [invalid-assignment]
+C2.meta_data_descriptor2 = "invalid"
 ```
 
 On the other hand, normal metaclass attributes and metaclass non-data descriptors are shadowed by
@@ -252,6 +367,16 @@ def _(flag: bool):
     reveal_type(C5.meta_data_descriptor1)  # revealed: Literal["data", "value on class"]
     # error: [possibly-unbound-attribute]
     reveal_type(C5.meta_data_descriptor2)  # revealed: Literal["data"]
+
+    # TODO: We currently emit two diagnostics here, corresponding to the two states of `flag`. The diagnostics are not
+    # wrong, but they could be subsumed under a higher-level diagnostic.
+
+    # error: [invalid-assignment] "Invalid assignment to data descriptor attribute `meta_data_descriptor1` on type `Literal[C5]` with custom `__set__` method"
+    # error: [invalid-assignment] "Object of type `None` is not assignable to attribute `meta_data_descriptor1` of type `Literal["value on class"]`"
+    C5.meta_data_descriptor1 = None
+
+    # error: [possibly-unbound-attribute]
+    C5.meta_data_descriptor2 = 1
 ```
 
 When a class-level attribute is possibly unbound, we union its (descriptor protocol) type with the
@@ -304,58 +429,71 @@ def _(flag: bool):
     reveal_type(C7.union_of_metaclass_data_descriptor_and_attribute)  # revealed: Literal["data", 2]
     reveal_type(C7.union_of_class_attributes)  # revealed: Literal[1, 2]
     reveal_type(C7.union_of_class_data_descriptor_and_attribute)  # revealed: Literal["data", 2]
+
+    C7.union_of_metaclass_attributes = 2 if flag else 1
+    C7.union_of_metaclass_data_descriptor_and_attribute = 2 if flag else 100
+    C7.union_of_class_attributes = 2 if flag else 1
+    C7.union_of_class_data_descriptor_and_attribute = 2 if flag else DataDescriptor()
 ```
 
-## Partial fall back
+## Descriptors distinguishing between class and instance access
 
-Our implementation of the descriptor protocol takes into account that symbols can be possibly
-unbound. In those cases, we fall back to lower precedence steps of the descriptor protocol and union
-all possible results accordingly. We start by defining a data and a non-data descriptor:
+Overloads can be used to distinguish between when a descriptor is accessed on a class object and
+when it is accessed on an instance. A real-world example of this is the `__get__` method on
+`types.FunctionType`.
 
 ```py
-from typing import Literal
+from typing_extensions import Literal, LiteralString, overload
 
-class DataDescriptor:
-    def __get__(self, instance: object, owner: type | None = None) -> Literal["data"]:
-        return "data"
+class Descriptor:
+    @overload
+    def __get__(self, instance: None, owner: type, /) -> Literal["called on class object"]: ...
+    @overload
+    def __get__(self, instance: object, owner: type | None = None, /) -> Literal["called on instance"]: ...
+    def __get__(self, instance, owner=None, /) -> LiteralString:
+        if instance:
+            return "called on instance"
+        else:
+            return "called on class object"
 
-    def __set__(self, instance: object, value: int) -> None:
-        pass
+class C:
+    d: Descriptor = Descriptor()
 
-class NonDataDescriptor:
-    def __get__(self, instance: object, owner: type | None = None) -> Literal["non-data"]:
-        return "non-data"
+# TODO: should be `Literal["called on class object"]
+reveal_type(C.d)  # revealed: LiteralString
+
+# TODO: should be `Literal["called on instance"]
+reveal_type(C().d)  # revealed: LiteralString
 ```
 
-Then, we demonstrate that we fall back to an instance attribute if a data descriptor is possibly
-unbound:
+## Descriptor protocol for dunder methods
+
+Dunder methods are always looked up on the meta-type. There is no instance fallback. This means that
+an implicit dunder call on an instance-like object will not only look up the dunder method on the
+class object, without considering instance attributes. And an implicit dunder call on a class object
+will look up the dunder method on the metaclass, without considering class attributes.
 
 ```py
-def f1(flag: bool):
-    class C1:
-        if flag:
-            attr = DataDescriptor()
+class SomeCallable:
+    def __call__(self, x: int) -> str:
+        return "a"
 
-        def f(self):
-            self.attr = "normal"
+class Descriptor:
+    def __get__(self, instance: object, owner: type | None = None) -> SomeCallable:
+        return SomeCallable()
 
-    reveal_type(C1().attr)  # revealed: Unknown | Literal["data", "normal"]
+class B:
+    __call__: Descriptor = Descriptor()
+
+b_instance = B()
+reveal_type(b_instance(1))  # revealed: str
+
+b_instance("bla")  # error: [invalid-argument-type]
 ```
 
-We never treat implicit instance attributes as definitely bound, so we fall back to the non-data
-descriptor here:
+## Special descriptors
 
-```py
-def f2(flag: bool):
-    class C2:
-        def f(self):
-            self.attr = "normal"
-        attr = NonDataDescriptor()
-
-    reveal_type(C2().attr)  # revealed: Unknown | Literal["non-data", "normal"]
-```
-
-## Built-in `property` descriptor
+### Built-in `property` descriptor
 
 The built-in `property` decorator creates a descriptor. The names for attribute reads/writes are
 determined by the return type of the `name` method and the parameter type of the setter,
@@ -392,11 +530,11 @@ c.name = "new"
 c.name = None
 
 # TODO: this should be an error, but with a proper error message
-# error: [invalid-assignment] "Object of type `Literal[42]` is not assignable to attribute `name` of type `<bound method `name` of `C`>`"
+# error: [invalid-assignment] "Implicit shadowing of function `name`; annotate to make it explicit if this is intentional"
 c.name = 42
 ```
 
-## Built-in `classmethod` descriptor
+### Built-in `classmethod` descriptor
 
 Similarly to `property`, `classmethod` decorator creates an implicit descriptor that binds the first
 argument to the class instead of the instance.
@@ -423,244 +561,7 @@ reveal_type(C.get_name())  # revealed: str
 reveal_type(C("42").get_name())  # revealed: str
 ```
 
-## Descriptors only work when used as class variables
-
-From the descriptor guide:
-
-> Descriptors only work when used as class variables. When put in instances, they have no effect.
-
-```py
-from typing import Literal
-
-class Ten:
-    def __get__(self, instance: object, owner: type | None = None) -> Literal[10]:
-        return 10
-
-class C:
-    def __init__(self):
-        self.ten: Ten = Ten()
-
-reveal_type(C().ten)  # revealed: Ten
-```
-
-## Descriptors distinguishing between class and instance access
-
-Overloads can be used to distinguish between when a descriptor is accessed on a class object and
-when it is accessed on an instance. A real-world example of this is the `__get__` method on
-`types.FunctionType`.
-
-```py
-from typing_extensions import Literal, LiteralString, overload
-
-class Descriptor:
-    @overload
-    def __get__(self, instance: None, owner: type, /) -> Literal["called on class object"]: ...
-    @overload
-    def __get__(self, instance: object, owner: type | None = None, /) -> Literal["called on instance"]: ...
-    def __get__(self, instance, owner=None, /) -> LiteralString:
-        if instance:
-            return "called on instance"
-        else:
-            return "called on class object"
-
-class C:
-    d: Descriptor = Descriptor()
-
-# TODO: should be `Literal["called on class object"]
-reveal_type(C.d)  # revealed: LiteralString
-
-# TODO: should be `Literal["called on instance"]
-reveal_type(C().d)  # revealed: LiteralString
-```
-
-## Undeclared descriptor arguments
-
-If a descriptor attribute is not declared, we union with `Unknown`, just like for regular
-attributes, since that attribute could be overwritten externally. Even a data descriptor with a
-`__set__` method can be overwritten when accessed through a class object.
-
-```py
-class Descriptor:
-    def __get__(self, instance: object, owner: type | None = None) -> int:
-        return 1
-
-    def __set__(self, instance: object, value: int) -> None:
-        pass
-
-class C:
-    descriptor = Descriptor()
-
-C.descriptor = "something else"
-
-# This could also be `Literal["something else"]` if we support narrowing of attribute types based on assignments
-reveal_type(C.descriptor)  # revealed: Unknown | int
-```
-
-## `__get__` is called with correct arguments
-
-```py
-from __future__ import annotations
-
-class TailoredForClassObjectAccess:
-    def __get__(self, instance: None, owner: type[C]) -> int:
-        return 1
-
-class TailoredForInstanceAccess:
-    def __get__(self, instance: C, owner: type[C] | None = None) -> str:
-        return "a"
-
-class TailoredForMetaclassAccess:
-    def __get__(self, instance: type[C], owner: type[Meta]) -> bytes:
-        return b"a"
-
-class Meta(type):
-    metaclass_access: TailoredForMetaclassAccess = TailoredForMetaclassAccess()
-
-class C(metaclass=Meta):
-    class_object_access: TailoredForClassObjectAccess = TailoredForClassObjectAccess()
-    instance_access: TailoredForInstanceAccess = TailoredForInstanceAccess()
-
-reveal_type(C.class_object_access)  # revealed: int
-reveal_type(C().instance_access)  # revealed: str
-reveal_type(C.metaclass_access)  # revealed: bytes
-
-# TODO: These should emit a diagnostic
-reveal_type(C().class_object_access)  # revealed: TailoredForClassObjectAccess
-reveal_type(C.instance_access)  # revealed: TailoredForInstanceAccess
-```
-
-## Descriptors with incorrect `__get__` signature
-
-```py
-class Descriptor:
-    # `__get__` method with missing parameters:
-    def __get__(self) -> int:
-        return 1
-
-class C:
-    descriptor: Descriptor = Descriptor()
-
-# TODO: This should be an error
-reveal_type(C.descriptor)  # revealed: Descriptor
-
-# TODO: This should be an error
-reveal_type(C().descriptor)  # revealed: Descriptor
-```
-
-## Possibly unbound descriptor attributes
-
-```py
-class DataDescriptor:
-    def __get__(self, instance: object, owner: type | None = None) -> int:
-        return 1
-
-    def __set__(self, instance: int, value) -> None:
-        pass
-
-class NonDataDescriptor:
-    def __get__(self, instance: object, owner: type | None = None) -> int:
-        return 1
-
-def _(flag: bool):
-    class PossiblyUnbound:
-        if flag:
-            non_data: NonDataDescriptor = NonDataDescriptor()
-            data: DataDescriptor = DataDescriptor()
-
-    # error: [possibly-unbound-attribute] "Attribute `non_data` on type `Literal[PossiblyUnbound]` is possibly unbound"
-    reveal_type(PossiblyUnbound.non_data)  # revealed: int
-
-    # error: [possibly-unbound-attribute] "Attribute `non_data` on type `PossiblyUnbound` is possibly unbound"
-    reveal_type(PossiblyUnbound().non_data)  # revealed: int
-
-    # error: [possibly-unbound-attribute] "Attribute `data` on type `Literal[PossiblyUnbound]` is possibly unbound"
-    reveal_type(PossiblyUnbound.data)  # revealed: int
-
-    # error: [possibly-unbound-attribute] "Attribute `data` on type `PossiblyUnbound` is possibly unbound"
-    reveal_type(PossiblyUnbound().data)  # revealed: int
-```
-
-## Possibly-unbound `__get__` method
-
-```py
-def _(flag: bool):
-    class MaybeDescriptor:
-        if flag:
-            def __get__(self, instance: object, owner: type | None = None) -> int:
-                return 1
-
-    class C:
-        descriptor: MaybeDescriptor = MaybeDescriptor()
-
-    reveal_type(C.descriptor)  # revealed: int | MaybeDescriptor
-
-    reveal_type(C().descriptor)  # revealed: int | MaybeDescriptor
-```
-
-## Descriptors with non-function `__get__` callables that are descriptors themselves
-
-The descriptor protocol is recursive, i.e. looking up `__get__` can involve triggering the
-descriptor protocol on the callable's `__call__` method:
-
-```py
-from __future__ import annotations
-
-class ReturnedCallable2:
-    def __call__(self, descriptor: Descriptor1, instance: None, owner: type[C]) -> int:
-        return 1
-
-class ReturnedCallable1:
-    def __call__(self, descriptor: Descriptor2, instance: Callable1, owner: type[Callable1]) -> ReturnedCallable2:
-        return ReturnedCallable2()
-
-class Callable3:
-    def __call__(self, descriptor: Descriptor3, instance: Callable2, owner: type[Callable2]) -> ReturnedCallable1:
-        return ReturnedCallable1()
-
-class Descriptor3:
-    __get__: Callable3 = Callable3()
-
-class Callable2:
-    __call__: Descriptor3 = Descriptor3()
-
-class Descriptor2:
-    __get__: Callable2 = Callable2()
-
-class Callable1:
-    __call__: Descriptor2 = Descriptor2()
-
-class Descriptor1:
-    __get__: Callable1 = Callable1()
-
-class C:
-    d: Descriptor1 = Descriptor1()
-
-reveal_type(C.d)  # revealed: int
-```
-
-## Dunder methods
-
-Dunder methods are looked up on the meta-type, but we still need to invoke the descriptor protocol:
-
-```py
-class SomeCallable:
-    def __call__(self, x: int) -> str:
-        return "a"
-
-class Descriptor:
-    def __get__(self, instance: object, owner: type | None = None) -> SomeCallable:
-        return SomeCallable()
-
-class B:
-    __call__: Descriptor = Descriptor()
-
-b_instance = B()
-reveal_type(b_instance(1))  # revealed: str
-
-b_instance("bla")  # error: [invalid-argument-type]
-```
-
-## Functions as descriptors
+### Functions as descriptors
 
 Functions are descriptors because they implement a `__get__` method. This is crucial in making sure
 that method calls work as expected. See [this test suite](./call/methods.md) for more information.
@@ -710,33 +611,202 @@ Finally, we test some error cases for the call to the wrapper descriptor:
 
 ```py
 # Calling the wrapper descriptor without any arguments is an
-# error: [missing-argument] "No arguments provided for required parameters `self`, `instance`"
+# error: [no-matching-overload] "No overload of wrapper descriptor `FunctionType.__get__` matches arguments"
 wrapper_descriptor()
 
 # Calling it without the `instance` argument is an also an
-# error: [missing-argument] "No argument provided for required parameter `instance`"
+# error: [no-matching-overload] "No overload of wrapper descriptor `FunctionType.__get__` matches arguments"
 wrapper_descriptor(f)
 
 # Calling it without the `owner` argument if `instance` is not `None` is an
-# error: [missing-argument] "No argument provided for required parameter `owner`"
+# error: [no-matching-overload] "No overload of wrapper descriptor `FunctionType.__get__` matches arguments"
 wrapper_descriptor(f, None)
 
 # But calling it with an instance is fine (in this case, the `owner` argument is optional):
 wrapper_descriptor(f, C())
 
 # Calling it with something that is not a `FunctionType` as the first argument is an
-# error: [invalid-argument-type] "Object of type `Literal[1]` cannot be assigned to parameter 1 (`self`) of wrapper descriptor `FunctionType.__get__`; expected type `FunctionType`"
+# error: [no-matching-overload] "No overload of wrapper descriptor `FunctionType.__get__` matches arguments"
 wrapper_descriptor(1, None, type(f))
 
 # Calling it with something that is not a `type` as the `owner` argument is an
-# error: [invalid-argument-type] "Object of type `Literal[f]` cannot be assigned to parameter 3 (`owner`) of wrapper descriptor `FunctionType.__get__`; expected type `type`"
+# error: [no-matching-overload] "No overload of wrapper descriptor `FunctionType.__get__` matches arguments"
 wrapper_descriptor(f, None, f)
 
 # Calling it with too many positional arguments is an
-# error: [too-many-positional-arguments] "Too many positional arguments to wrapper descriptor `FunctionType.__get__`: expected 3, got 4"
+# error: [no-matching-overload] "No overload of wrapper descriptor `FunctionType.__get__` matches arguments"
 wrapper_descriptor(f, None, type(f), "one too many")
 ```
 
+## Error handling and edge cases
+
+### `__get__` is called with correct arguments
+
+This test makes sure that we call `__get__` with the right argument types for various scenarios:
+
+```py
+from __future__ import annotations
+
+class TailoredForClassObjectAccess:
+    def __get__(self, instance: None, owner: type[C]) -> int:
+        return 1
+
+class TailoredForInstanceAccess:
+    def __get__(self, instance: C, owner: type[C] | None = None) -> str:
+        return "a"
+
+class TailoredForMetaclassAccess:
+    def __get__(self, instance: type[C], owner: type[Meta]) -> bytes:
+        return b"a"
+
+class Meta(type):
+    metaclass_access: TailoredForMetaclassAccess = TailoredForMetaclassAccess()
+
+class C(metaclass=Meta):
+    class_object_access: TailoredForClassObjectAccess = TailoredForClassObjectAccess()
+    instance_access: TailoredForInstanceAccess = TailoredForInstanceAccess()
+
+reveal_type(C.class_object_access)  # revealed: int
+reveal_type(C().instance_access)  # revealed: str
+reveal_type(C.metaclass_access)  # revealed: bytes
+
+# TODO: These should emit a diagnostic
+reveal_type(C().class_object_access)  # revealed: TailoredForClassObjectAccess
+reveal_type(C.instance_access)  # revealed: TailoredForInstanceAccess
+```
+
+### Descriptors with incorrect `__get__` signature
+
+```py
+class Descriptor:
+    # `__get__` method with missing parameters:
+    def __get__(self) -> int:
+        return 1
+
+class C:
+    descriptor: Descriptor = Descriptor()
+
+# TODO: This should be an error
+reveal_type(C.descriptor)  # revealed: Descriptor
+
+# TODO: This should be an error
+reveal_type(C().descriptor)  # revealed: Descriptor
+```
+
+### Undeclared descriptor arguments
+
+If a descriptor attribute is not declared, we union with `Unknown`, just like for regular
+attributes, since that attribute could be overwritten externally. Even a data descriptor with a
+`__set__` method can be overwritten when accessed through a class object.
+
+```py
+class Descriptor:
+    def __get__(self, instance: object, owner: type | None = None) -> int:
+        return 1
+
+    def __set__(self, instance: object, value: int) -> None:
+        pass
+
+class C:
+    descriptor = Descriptor()
+
+C.descriptor = "something else"
+
+# This could also be `Literal["something else"]` if we support narrowing of attribute types based on assignments
+reveal_type(C.descriptor)  # revealed: Unknown | int
+```
+
+### Possibly unbound descriptor attributes
+
+```py
+class DataDescriptor:
+    def __get__(self, instance: object, owner: type | None = None) -> int:
+        return 1
+
+    def __set__(self, instance: int, value) -> None:
+        pass
+
+class NonDataDescriptor:
+    def __get__(self, instance: object, owner: type | None = None) -> int:
+        return 1
+
+def _(flag: bool):
+    class PossiblyUnbound:
+        if flag:
+            non_data: NonDataDescriptor = NonDataDescriptor()
+            data: DataDescriptor = DataDescriptor()
+
+    # error: [possibly-unbound-attribute] "Attribute `non_data` on type `Literal[PossiblyUnbound]` is possibly unbound"
+    reveal_type(PossiblyUnbound.non_data)  # revealed: int
+
+    # error: [possibly-unbound-attribute] "Attribute `non_data` on type `PossiblyUnbound` is possibly unbound"
+    reveal_type(PossiblyUnbound().non_data)  # revealed: int
+
+    # error: [possibly-unbound-attribute] "Attribute `data` on type `Literal[PossiblyUnbound]` is possibly unbound"
+    reveal_type(PossiblyUnbound.data)  # revealed: int
+
+    # error: [possibly-unbound-attribute] "Attribute `data` on type `PossiblyUnbound` is possibly unbound"
+    reveal_type(PossiblyUnbound().data)  # revealed: int
+```
+
+### Possibly-unbound `__get__` method
+
+```py
+def _(flag: bool):
+    class MaybeDescriptor:
+        if flag:
+            def __get__(self, instance: object, owner: type | None = None) -> int:
+                return 1
+
+    class C:
+        descriptor: MaybeDescriptor = MaybeDescriptor()
+
+    reveal_type(C.descriptor)  # revealed: int | MaybeDescriptor
+
+    reveal_type(C().descriptor)  # revealed: int | MaybeDescriptor
+```
+
+### Descriptors with non-function `__get__` callables that are descriptors themselves
+
+The descriptor protocol is recursive, i.e. looking up `__get__` can involve triggering the
+descriptor protocol on the callable's `__call__` method:
+
+```py
+from __future__ import annotations
+
+class ReturnedCallable2:
+    def __call__(self, descriptor: Descriptor1, instance: None, owner: type[C]) -> int:
+        return 1
+
+class ReturnedCallable1:
+    def __call__(self, descriptor: Descriptor2, instance: Callable1, owner: type[Callable1]) -> ReturnedCallable2:
+        return ReturnedCallable2()
+
+class Callable3:
+    def __call__(self, descriptor: Descriptor3, instance: Callable2, owner: type[Callable2]) -> ReturnedCallable1:
+        return ReturnedCallable1()
+
+class Descriptor3:
+    __get__: Callable3 = Callable3()
+
+class Callable2:
+    __call__: Descriptor3 = Descriptor3()
+
+class Descriptor2:
+    __get__: Callable2 = Callable2()
+
+class Callable1:
+    __call__: Descriptor2 = Descriptor2()
+
+class Descriptor1:
+    __get__: Callable1 = Callable1()
+
+class C:
+    d: Descriptor1 = Descriptor1()
+
+reveal_type(C.d)  # revealed: int
+```
+
 [descriptors]: https://docs.python.org/3/howto/descriptor.html
 [precedence chain]: https://github.com/python/cpython/blob/3.13/Objects/typeobject.c#L5393-L5481
 [simple example]: https://docs.python.org/3/howto/descriptor.html#simple-example-a-descriptor-that-returns-a-constant

crates/red_knot_python_semantic/resources/mdtest/diagnostics/attribute_assignment.md

@@ -0,0 +1,149 @@
+# Attribute assignment
+
+<!-- snapshot-diagnostics -->
+
+This test suite demonstrates various kinds of diagnostics that can be emitted in a
+`obj.attr = value` assignment.
+
+## Instance attributes with class-level defaults
+
+These can be set on instances and on class objects.
+
+```py
+class C:
+    attr: int = 0
+
+instance = C()
+instance.attr = 1  # fine
+instance.attr = "wrong"  # error: [invalid-assignment]
+
+C.attr = 1  # fine
+C.attr = "wrong"  # error: [invalid-assignment]
+```
+
+## Pure instance attributes
+
+These can only be set on instances. When trying to set them on class objects, we generate a useful
+diagnostic that mentions that the attribute is only available on instances.
+
+```py
+class C:
+    def __init__(self):
+        self.attr: int = 0
+
+instance = C()
+instance.attr = 1  # fine
+instance.attr = "wrong"  # error: [invalid-assignment]
+
+C.attr = 1  # error: [invalid-attribute-access]
+```
+
+## `ClassVar`s
+
+These can only be set on class objects. When trying to set them on instances, we generate a useful
+diagnostic that mentions that the attribute is only available on class objects.
+
+```py
+from typing import ClassVar
+
+class C:
+    attr: ClassVar[int] = 0
+
+C.attr = 1  # fine
+C.attr = "wrong"  # error: [invalid-assignment]
+
+instance = C()
+instance.attr = 1  # error: [invalid-attribute-access]
+```
+
+## Unknown attributes
+
+When trying to set an attribute that is not defined, we also emit errors:
+
+```py
+class C: ...
+
+C.non_existent = 1  # error: [unresolved-attribute]
+
+instance = C()
+instance.non_existent = 1  # error: [unresolved-attribute]
+```
+
+## Possibly-unbound attributes
+
+When trying to set an attribute that is not defined in all branches, we emit errors:
+
+```py
+def _(flag: bool) -> None:
+    class C:
+        if flag:
+            attr: int = 0
+
+    C.attr = 1  # error: [possibly-unbound-attribute]
+
+    instance = C()
+    instance.attr = 1  # error: [possibly-unbound-attribute]
+```
+
+## Data descriptors
+
+When assigning to a data descriptor attribute, we implicitly call the descriptor's `__set__` method.
+This can lead to various kinds of diagnostics.
+
+### Invalid argument type
+
+```py
+class Descriptor:
+    def __set__(self, instance: object, value: int) -> None:
+        pass
+
+class C:
+    attr: Descriptor = Descriptor()
+
+instance = C()
+instance.attr = 1  # fine
+
+# TODO: ideally, we would mention why this is an invalid assignment (wrong argument type for `value` parameter)
+instance.attr = "wrong"  # error: [invalid-assignment]
+```
+
+### Invalid `__set__` method signature
+
+```py
+class WrongDescriptor:
+    def __set__(self, instance: object, value: int, extra: int) -> None:
+        pass
+
+class C:
+    attr: WrongDescriptor = WrongDescriptor()
+
+instance = C()
+
+# TODO: ideally, we would mention why this is an invalid assignment (wrong number of arguments for `__set__`)
+instance.attr = 1  # error: [invalid-assignment]
+```
+
+## Setting attributes on union types
+
+```py
+def _(flag: bool) -> None:
+    if flag:
+        class C1:
+            attr: int = 0
+
+    else:
+        class C1:
+            attr: str = ""
+
+    # TODO: The error message here could be improved to explain why the assignment fails.
+    C1.attr = 1  # error: [invalid-assignment]
+
+    class C2:
+        if flag:
+            attr: int = 0
+        else:
+            attr: str = ""
+
+    # TODO: This should be an error
+    C2.attr = 1
+```

crates/red_knot_python_semantic/resources/mdtest/diagnostics/no_matching_overload.md

@@ -0,0 +1,14 @@
+# No matching overload diagnostics
+
+<!-- snapshot-diagnostics -->
+
+## Calls to overloaded functions
+
+TODO: Note that we do not yet support the `@overload` decorator to define overloaded functions in
+real Python code. We are instead testing a special-cased function where we create an overloaded
+signature internally. Update this to an `@overload` function in the Python snippet itself once we
+can.
+
+```py
+type("Foo", ())  # error: [no-matching-overload]
+```

crates/red_knot_python_semantic/resources/mdtest/directives/cast.md

@@ -16,8 +16,10 @@ reveal_type(cast(int | str, 1))  # revealed: int | str
 # error: [invalid-type-form]
 reveal_type(cast(Literal, True))  # revealed: Unknown
 
+# error: [invalid-type-form]
+reveal_type(cast(1, True))  # revealed: Unknown
+
 # TODO: These should be errors
-cast(1)
 cast(str)
 cast(str, b"ar", "foo")
 

crates/red_knot_python_semantic/resources/mdtest/expression/assert.md

@@ -2,7 +2,7 @@
 
 ```py
 class NotBoolable:
-    __bool__ = 3
+    __bool__: int = 3
 
 # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
 assert NotBoolable()

crates/red_knot_python_semantic/resources/mdtest/expression/boolean.md

@@ -121,7 +121,7 @@ if NotBoolable():
 
 ```py
 class NotBoolable:
-    __bool__ = None
+    __bool__: None = None
 
 # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
 if NotBoolable():
@@ -133,9 +133,9 @@ if NotBoolable():
 ```py
 def test(cond: bool):
     class NotBoolable:
-        __bool__ = None if cond else 3
+        __bool__: int | None = None if cond else 3
 
-    # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; it incorrectly implements `__bool__`"
+    # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
     if NotBoolable():
         ...
 ```
@@ -145,7 +145,7 @@ def test(cond: bool):
 ```py
 def test(cond: bool):
     class NotBoolable:
-        __bool__ = None
+        __bool__: None = None
 
     a = 10 if cond else NotBoolable()
 

crates/red_knot_python_semantic/resources/mdtest/expression/lambda.md

@@ -5,10 +5,10 @@
 `lambda` expressions can be defined without any parameters.
 
 ```py
-reveal_type(lambda: 1)  # revealed: () -> @Todo(lambda return type)
+reveal_type(lambda: 1)  # revealed: () -> Unknown
 
 # error: [unresolved-reference]
-reveal_type(lambda: a)  # revealed: () -> @Todo(lambda return type)
+reveal_type(lambda: a)  # revealed: () -> Unknown
 ```
 
 ## With parameters
@@ -17,45 +17,45 @@ Unlike parameters in function definition, the parameters in a `lambda` expressio
 annotated.
 
 ```py
-reveal_type(lambda a: a)  # revealed: (a) -> @Todo(lambda return type)
-reveal_type(lambda a, b: a + b)  # revealed: (a, b) -> @Todo(lambda return type)
+reveal_type(lambda a: a)  # revealed: (a) -> Unknown
+reveal_type(lambda a, b: a + b)  # revealed: (a, b) -> Unknown
 ```
 
 But, it can have default values:
 
 ```py
-reveal_type(lambda a=1: a)  # revealed: (a=Literal[1]) -> @Todo(lambda return type)
-reveal_type(lambda a, b=2: a)  # revealed: (a, b=Literal[2]) -> @Todo(lambda return type)
+reveal_type(lambda a=1: a)  # revealed: (a=Literal[1]) -> Unknown
+reveal_type(lambda a, b=2: a)  # revealed: (a, b=Literal[2]) -> Unknown
 ```
 
 And, positional-only parameters:
 
 ```py
-reveal_type(lambda a, b, /, c: c)  # revealed: (a, b, /, c) -> @Todo(lambda return type)
+reveal_type(lambda a, b, /, c: c)  # revealed: (a, b, /, c) -> Unknown
 ```
 
 And, keyword-only parameters:
 
 ```py
-reveal_type(lambda a, *, b=2, c: b)  # revealed: (a, *, b=Literal[2], c) -> @Todo(lambda return type)
+reveal_type(lambda a, *, b=2, c: b)  # revealed: (a, *, b=Literal[2], c) -> Unknown
 ```
 
 And, variadic parameter:
 
 ```py
-reveal_type(lambda *args: args)  # revealed: (*args) -> @Todo(lambda return type)
+reveal_type(lambda *args: args)  # revealed: (*args) -> Unknown
 ```
 
 And, keyword-varidic parameter:
 
 ```py
-reveal_type(lambda **kwargs: kwargs)  # revealed: (**kwargs) -> @Todo(lambda return type)
+reveal_type(lambda **kwargs: kwargs)  # revealed: (**kwargs) -> Unknown
 ```
 
 Mixing all of them together:
 
 ```py
-# revealed: (a, b, /, c=Literal[True], *args, *, d=Literal["default"], e=Literal[5], **kwargs) -> @Todo(lambda return type)
+# revealed: (a, b, /, c=Literal[True], *args, *, d=Literal["default"], e=Literal[5], **kwargs) -> Unknown
 reveal_type(lambda a, b, /, c=True, *args, d="default", e=5, **kwargs: None)
 ```
 
@@ -96,5 +96,5 @@ Here, a `lambda` expression is used as the default value for a parameter in anot
 expression.
 
 ```py
-reveal_type(lambda a=lambda x, y: 0: 2)  # revealed: (a=(x, y) -> @Todo(lambda return type)) -> @Todo(lambda return type)
+reveal_type(lambda a=lambda x, y: 0: 2)  # revealed: (a=(x, y) -> Unknown) -> Unknown
 ```

crates/red_knot_python_semantic/resources/mdtest/expression/len.md

@@ -99,22 +99,28 @@ The returned value of `__len__` is implicitly and recursively converted to `int`
 from typing import Literal
 
 class Zero:
-    def __len__(self) -> Literal[0]: ...
+    def __len__(self) -> Literal[0]:
+        return 0
 
 class ZeroOrOne:
-    def __len__(self) -> Literal[0, 1]: ...
+    def __len__(self) -> Literal[0, 1]:
+        return 0
 
 class ZeroOrTrue:
-    def __len__(self) -> Literal[0, True]: ...
+    def __len__(self) -> Literal[0, True]:
+        return 0
 
 class OneOrFalse:
-    def __len__(self) -> Literal[1] | Literal[False]: ...
+    def __len__(self) -> Literal[1] | Literal[False]:
+        return 1
 
 class OneOrFoo:
-    def __len__(self) -> Literal[1, "foo"]: ...
+    def __len__(self) -> Literal[1, "foo"]:
+        return 1
 
 class ZeroOrStr:
-    def __len__(self) -> Literal[0] | str: ...
+    def __len__(self) -> Literal[0] | str:
+        return 0
 
 reveal_type(len(Zero()))  # revealed: Literal[0]
 reveal_type(len(ZeroOrOne()))  # revealed: Literal[0, 1]
@@ -134,10 +140,12 @@ reveal_type(len(ZeroOrStr()))  # revealed: int
 from typing import Literal
 
 class LiteralTrue:
-    def __len__(self) -> Literal[True]: ...
+    def __len__(self) -> Literal[True]:
+        return True
 
 class LiteralFalse:
-    def __len__(self) -> Literal[False]: ...
+    def __len__(self) -> Literal[False]:
+        return False
 
 reveal_type(len(LiteralTrue()))  # revealed: Literal[1]
 reveal_type(len(LiteralFalse()))  # revealed: Literal[0]
@@ -157,19 +165,24 @@ class SomeEnum(Enum):
     INT_2 = 3_2
 
 class Auto:
-    def __len__(self) -> Literal[SomeEnum.AUTO]: ...
+    def __len__(self) -> Literal[SomeEnum.AUTO]:
+        return SomeEnum.AUTO
 
 class Int:
-    def __len__(self) -> Literal[SomeEnum.INT]: ...
+    def __len__(self) -> Literal[SomeEnum.INT]:
+        return SomeEnum.INT
 
 class Str:
-    def __len__(self) -> Literal[SomeEnum.STR]: ...
+    def __len__(self) -> Literal[SomeEnum.STR]:
+        return SomeEnum.STR
 
 class Tuple:
-    def __len__(self) -> Literal[SomeEnum.TUPLE]: ...
+    def __len__(self) -> Literal[SomeEnum.TUPLE]:
+        return SomeEnum.TUPLE
 
 class IntUnion:
-    def __len__(self) -> Literal[SomeEnum.INT, SomeEnum.INT_2]: ...
+    def __len__(self) -> Literal[SomeEnum.INT, SomeEnum.INT_2]:
+        return SomeEnum.INT
 
 reveal_type(len(Auto()))  # revealed: int
 reveal_type(len(Int()))  # revealed: int
@@ -184,7 +197,8 @@ reveal_type(len(IntUnion()))  # revealed: int
 from typing import Literal
 
 class Negative:
-    def __len__(self) -> Literal[-1]: ...
+    def __len__(self) -> Literal[-1]:
+        return -1
 
 # TODO: Emit a diagnostic
 reveal_type(len(Negative()))  # revealed: int
@@ -196,10 +210,12 @@ reveal_type(len(Negative()))  # revealed: int
 from typing import Literal
 
 class SecondOptionalArgument:
-    def __len__(self, v: int = 0) -> Literal[0]: ...
+    def __len__(self, v: int = 0) -> Literal[0]:
+        return 0
 
 class SecondRequiredArgument:
-    def __len__(self, v: int) -> Literal[1]: ...
+    def __len__(self, v: int) -> Literal[1]:
+        return 1
 
 # TODO: Emit a diagnostic
 reveal_type(len(SecondOptionalArgument()))  # revealed: Literal[0]

crates/red_knot_python_semantic/resources/mdtest/function/return_type.md

@@ -0,0 +1,245 @@
+# Function return type
+
+When a function's return type is annotated, all return statements are checked to ensure that the
+type of the returned value is assignable to the annotated return type.
+
+## Basic examples
+
+A return value assignable to the annotated return type is valid.
+
+```py
+def f() -> int:
+    return 1
+```
+
+The type of the value obtained by calling a function is the annotated return type, not the inferred
+return type.
+
+```py
+reveal_type(f())  # revealed: int
+```
+
+A `raise` is equivalent to a return of `Never`, which is assignable to any annotated return type.
+
+```py
+def f() -> str:
+    raise ValueError()
+
+reveal_type(f())  # revealed: str
+```
+
+## Stub functions
+
+"Stub" function definitions (that is, function definitions with an empty body) are permissible in
+stub files, or in a few other locations: Protocol method definitions, abstract methods, and
+overloads. In this case the function body is considered to be omitted (thus no return type checking
+is performed on it), not assumed to implicitly return `None`.
+
+A stub function's "empty" body may contain only an optional docstring, followed (optionally) by an
+ellipsis (`...`) or `pass`.
+
+### In stub file
+
+```pyi
+def f() -> int: ...
+
+def f() -> int:
+    pass
+
+def f() -> int:
+    """Some docstring"""
+
+def f() -> int:
+    """Some docstring"""
+    ...
+```
+
+### In Protocol
+
+```py
+from typing import Protocol
+
+class Bar(Protocol):
+    # TODO: no error
+    # error: [invalid-return-type]
+    def f(self) -> int: ...
+```
+
+### In abstract method
+
+```py
+from abc import ABC, abstractmethod
+
+class Foo(ABC):
+    @abstractmethod
+    # TODO: no error
+    # error: [invalid-return-type]
+    def f(self) -> int: ...
+    @abstractmethod
+    # error: [invalid-return-type]
+    def g[T](self, x: T) -> T: ...
+```
+
+### In overload
+
+```py
+from typing import overload
+
+@overload
+def f(x: int) -> int: ...
+@overload
+def f(x: str) -> str: ...
+def f(x: int | str):
+    return x
+```
+
+## Conditional return type
+
+```py
+def f(cond: bool) -> int:
+    if cond:
+        return 1
+    else:
+        return 2
+
+def f(cond: bool) -> int | None:
+    if cond:
+        return 1
+    else:
+        return
+
+def f(cond: bool) -> int:
+    if cond:
+        return 1
+    else:
+        raise ValueError()
+
+def f(cond: bool) -> str | int:
+    if cond:
+        return "a"
+    else:
+        return 1
+```
+
+## Implicit return type
+
+```py
+def f(cond: bool) -> int | None:
+    if cond:
+        return 1
+
+# no implicit return
+def f() -> int:
+    if True:
+        return 1
+
+# no implicit return
+def f(cond: bool) -> int:
+    cond = True
+    if cond:
+        return 1
+
+def f(cond: bool) -> int:
+    if cond:
+        cond = True
+    else:
+        return 1
+    if cond:
+        return 2
+```
+
+## Invalid return type
+
+<!-- snapshot-diagnostics -->
+
+```py
+# error: [invalid-return-type]
+def f() -> int:
+    1
+
+def f() -> str:
+    # error: [invalid-return-type]
+    return 1
+
+def f() -> int:
+    # error: [invalid-return-type]
+    return
+
+from typing import TypeVar
+
+T = TypeVar("T")
+
+# TODO: `invalid-return-type` error should be emitted
+def m(x: T) -> T: ...
+```
+
+## Invalid return type in stub file
+
+<!-- snapshot-diagnostics -->
+
+```pyi
+def f() -> int:
+    # error: [invalid-return-type]
+    return ...
+
+# error: [invalid-return-type]
+def foo() -> int:
+    print("...")
+    ...
+
+# error: [invalid-return-type]
+def foo() -> int:
+    f"""{foo} is a function that ..."""
+    ...
+```
+
+## Invalid conditional return type
+
+<!-- snapshot-diagnostics -->
+
+```py
+def f(cond: bool) -> str:
+    if cond:
+        return "a"
+    else:
+        # error: [invalid-return-type]
+        return 1
+
+def f(cond: bool) -> str:
+    if cond:
+        # error: [invalid-return-type]
+        return 1
+    else:
+        # error: [invalid-return-type]
+        return 2
+```
+
+## Invalid implicit return type
+
+<!-- snapshot-diagnostics -->
+
+```py
+def f() -> None:
+    if False:
+        # error: [invalid-return-type]
+        return 1
+
+# error: [invalid-return-type]
+def f(cond: bool) -> int:
+    if cond:
+        return 1
+
+# error: [invalid-return-type]
+def f(cond: bool) -> int:
+    if cond:
+        raise ValueError()
+
+# error: [invalid-return-type]
+def f(cond: bool) -> int:
+    if cond:
+        cond = False
+    else:
+        return 1
+    if cond:
+        return 2
+```

crates/red_knot_python_semantic/resources/mdtest/generics/classes.md

@@ -162,6 +162,8 @@ class Sub(Base[Sub]): ...
 reveal_type(Sub)  # revealed: Literal[Sub]
 ```
 
+A similar case can work in a non-stub file, if forward references are stringified:
+
 `string_annotation.py`:
 
 ```py
@@ -174,14 +176,25 @@ class Sub(Base["Sub"]): ...
 reveal_type(Sub)  # revealed: Literal[Sub]
 ```
 
+In a non-stub file, without stringified forward references, this raises a `NameError`:
+
 `bare_annotation.py`:
 
 ```py
 class Base[T]: ...
 
 # TODO: error: [unresolved-reference]
+# error: [non-subscriptable]
 class Sub(Base[Sub]): ...
 ```
 
+## Another cyclic case
+
+```pyi
+# TODO no error (generics)
+# error: [invalid-base]
+class Derived[T](list[Derived[T]]): ...
+```
+
 [crtp]: https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern
 [f-bound]: https://en.wikipedia.org/wiki/Bounded_quantification#F-bounded_quantification

crates/red_knot_python_semantic/resources/mdtest/generics/functions.md

@@ -35,7 +35,7 @@ Each typevar must also appear _somewhere_ in the parameter list:
 ```py
 def absurd[T]() -> T:
     # There's no way to construct a T!
-    ...
+    raise ValueError("absurd")
 ```
 
 ## Inferring generic function parameter types
@@ -48,7 +48,8 @@ whether we want to infer a more specific `Literal` type where possible, or use h
 the inferred type to e.g. `int`.
 
 ```py
-def f[T](x: T) -> T: ...
+def f[T](x: T) -> T:
+    return x
 
 # TODO: no error
 # TODO: revealed: int or Literal[1]
@@ -77,7 +78,8 @@ The matching up of call arguments and discovery of constraints on typevars can b
 process for arbitrarily-nested generic types in parameters.
 
 ```py
-def f[T](x: list[T]) -> T: ...
+def f[T](x: list[T]) -> T:
+    return x[0]
 
 # TODO: revealed: float
 reveal_type(f([1.0, 2.0]))  # revealed: T
@@ -119,7 +121,7 @@ def different_types[T, S](cond: bool, t: T, s: S) -> T:
     if cond:
         return t
     else:
-        # TODO: error: S is not assignable to T
+        # error: [invalid-return-type] "Object of type `S` is not assignable to return type `T`"
         return s
 
 def same_types[T](cond: bool, t1: T, t2: T) -> T:

crates/red_knot_python_semantic/resources/mdtest/generics/scoping.md

@@ -37,8 +37,11 @@ from typing import TypeVar
 
 T = TypeVar("T")
 
-def f1(x: T) -> T: ...
-def f2(x: T) -> T: ...
+def f1(x: T) -> T:
+    return x
+
+def f2(x: T) -> T:
+    return x
 
 f1(1)
 f2("a")
@@ -53,7 +56,8 @@ This also applies to a single generic function being used multiple times, instan
 to a different type each time.
 
 ```py
-def f[T](x: T) -> T: ...
+def f[T](x: T) -> T:
+    return x
 
 # TODO: no error
 # TODO: revealed: int or Literal[1]
@@ -72,8 +76,11 @@ reveal_type(f("a"))  # revealed: T
 
 ```py
 class C[T]:
-    def m1(self, x: T) -> T: ...
-    def m2(self, x: T) -> T: ...
+    def m1(self, x: T) -> T:
+        return x
+
+    def m2(self, x: T) -> T:
+        return x
 
 c: C[int] = C()
 # TODO: no error
@@ -101,18 +108,20 @@ S = TypeVar("S")
 # TODO: no error
 # error: [invalid-base]
 class Legacy(Generic[T]):
-    def m(self, x: T, y: S) -> S: ...
+    def m(self, x: T, y: S) -> S:
+        return y
 
 legacy: Legacy[int] = Legacy()
 # TODO: revealed: str
-reveal_type(legacy.m(1, "string"))  # revealed: @Todo(Invalid or unsupported `Instance` in `Type::to_type_expression`)
+reveal_type(legacy.m(1, "string"))  # revealed: @Todo(Support for `typing.TypeVar` instances in type expressions)
 ```
 
 With PEP 695 syntax, it is clearer that the method uses a separate typevar:
 
 ```py
 class C[T]:
-    def m[S](self, x: T, y: S) -> S: ...
+    def m[S](self, x: T, y: S) -> S:
+        return y
 
 c: C[int] = C()
 # TODO: no errors
@@ -147,7 +156,8 @@ class C(Generic[T]):
     x: list[S] = []
 
     # This is not an error, as shown in the previous test
-    def m(self, x: S) -> S: ...
+    def m(self, x: S) -> S:
+        return x
 ```
 
 This is true with PEP 695 syntax, as well, though we must use the legacy syntax to define the
@@ -169,8 +179,11 @@ class C[T]:
     # TODO: error
     x: list[S] = []
 
-    def m1(self, x: S) -> S: ...
-    def m2[S](self, x: S) -> S: ...
+    def m1(self, x: S) -> S:
+        return x
+
+    def m2[S](self, x: S) -> S:
+        return x
 ```
 
 ## Nested formal typevars must be distinct

crates/red_knot_python_semantic/resources/mdtest/import/basic.md

@@ -140,3 +140,27 @@ import b.foo  # error: [unresolved-import] "Cannot resolve import `b.foo`"
 
 ```py
 ```
+
+## Long paths
+
+It's unlikely that a single module component is as long as in this example, but Windows treats paths
+that are longer than 200 and something specially. This test ensures that Red Knot can handle those
+paths gracefully.
+
+```toml
+system = "os"
+```
+
+`AveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPath/__init__.py`:
+
+```py
+class Foo: ...
+```
+
+```py
+from AveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPathAveryLongPath import (
+    Foo,
+)
+
+reveal_type(Foo())  # revealed: Foo
+```

crates/red_knot_python_semantic/resources/mdtest/import/case_sensitive.md

@@ -1,10 +1,7 @@
 # Case Sensitive Imports
 
 ```toml
-# TODO: This test should use the real file system instead of the memory file system.
-# but we can't change the file system yet because the tests would then start failing for 
-# case-insensitive file systems.
-#system = "os"
+system = "os"
 ```
 
 Python's import system is case-sensitive even on case-insensitive file system. This means, importing

crates/red_knot_python_semantic/resources/mdtest/intersection_types.md

@@ -663,6 +663,7 @@ to the fact that `bool` is a `@final` class at runtime that cannot be subclassed
 
 ```py
 from knot_extensions import Intersection, Not, AlwaysTruthy, AlwaysFalsy
+from typing_extensions import Literal
 
 class P: ...
 
@@ -686,6 +687,19 @@ def f(
     reveal_type(f)  # revealed: Never
     reveal_type(g)  # revealed: Never
     reveal_type(h)  # revealed: Never
+
+def never(
+    a: Intersection[Intersection[AlwaysFalsy, Not[Literal[False]]], bool],
+    b: Intersection[Intersection[AlwaysTruthy, Not[Literal[True]]], bool],
+    c: Intersection[Intersection[Literal[True], Not[AlwaysTruthy]], bool],
+    d: Intersection[Intersection[Literal[False], Not[AlwaysFalsy]], bool],
+):
+    # TODO: This should be `Never`
+    reveal_type(a)  # revealed: Literal[True]
+    # TODO: This should be `Never`
+    reveal_type(b)  # revealed: Literal[False]
+    reveal_type(c)  # revealed: Never
+    reveal_type(d)  # revealed: Never
 ```
 
 ## Simplification of `LiteralString`, `AlwaysTruthy` and `AlwaysFalsy`
@@ -846,5 +860,19 @@ def mixed(
     reveal_type(i4)  # revealed: Any & Unknown
 ```
 
+## Invalid
+
+```py
+from knot_extensions import Intersection, Not
+
+# error: [invalid-type-form] "`knot_extensions.Intersection` requires at least one argument when used in a type expression"
+def f(x: Intersection) -> None:
+    reveal_type(x)  # revealed: Unknown
+
+# error: [invalid-type-form] "`knot_extensions.Not` requires exactly one argument when used in a type expression"
+def f(x: Not) -> None:
+    reveal_type(x)  # revealed: Unknown
+```
+
 [complement laws]: https://en.wikipedia.org/wiki/Complement_(set_theory)
 [de morgan's laws]: https://en.wikipedia.org/wiki/De_Morgan%27s_laws

crates/red_knot_python_semantic/resources/mdtest/loops/for.md

@@ -431,7 +431,7 @@ def _(flag: bool):
         # invalid signature because it only accepts a `str`,
         # but the old-style iteration protocol will pass it an `int`
         def __getitem__(self, key: str) -> bytes:
-            return 42
+            return bytes()
 
     # error: [not-iterable]
     for x in Iterable():
@@ -484,7 +484,7 @@ def _(flag1: bool, flag2: bool):
                 return Iterator()
         if flag2:
             def __getitem__(self, key: int) -> bytes:
-                return 42
+                return bytes()
 
     # error: [not-iterable]
     for x in Iterable():
@@ -682,7 +682,7 @@ def _(flag: bool):
                 return "foo"
         else:
             def __getitem__(self, item: str) -> int:
-                return "foo"
+                return 42
 
     # error: [not-iterable]
     for x in Iterable1():
@@ -723,7 +723,7 @@ def _(flag: bool, flag2: bool):
                 return "foo"
         else:
             def __getitem__(self, item: str) -> int:
-                return "foo"
+                return 42
         if flag2:
             def __iter__(self) -> Iterator:
                 return Iterator()

crates/red_knot_python_semantic/resources/mdtest/loops/iterators.md

@@ -10,7 +10,8 @@ class Iterator:
         return 42
 
 class Iterable:
-    def __iter__(self) -> Iterator: ...
+    def __iter__(self) -> Iterator:
+        return Iterator()
 
 def generator_function():
     yield from Iterable()

crates/red_knot_python_semantic/resources/mdtest/loops/while_loop.md

@@ -121,7 +121,7 @@ def _(flag: bool, flag2: bool):
 
 ```py
 class NotBoolable:
-    __bool__ = 3
+    __bool__: int = 3
 
 # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
 while NotBoolable():

crates/red_knot_python_semantic/resources/mdtest/metaclass.md

@@ -166,7 +166,8 @@ When a class has an explicit `metaclass` that is not a class, but is a callable
 `type.__new__` arguments, we should return the meta-type of its return type.
 
 ```py
-def f(*args, **kwargs) -> int: ...
+def f(*args, **kwargs) -> int:
+    return 1
 
 class A(metaclass=f): ...
 

crates/red_knot_python_semantic/resources/mdtest/narrow/bool-call.md

@@ -22,11 +22,13 @@ def _(flag: bool):
 
     # invalid invocation, too many positional args
     reveal_type(x)  # revealed: Literal[1] | None
-    if bool(x is not None, 5):  # TODO diagnostic
+    # error: [too-many-positional-arguments] "Too many positional arguments to class `bool`: expected 1, got 2"
+    if bool(x is not None, 5):
         reveal_type(x)  # revealed: Literal[1] | None
 
     # invalid invocation, too many kwargs
     reveal_type(x)  # revealed: Literal[1] | None
-    if bool(x is not None, y=5):  # TODO diagnostic
+    # error: [unknown-argument] "Argument `y` does not match any known parameter of class `bool`"
+    if bool(x is not None, y=5):
         reveal_type(x)  # revealed: Literal[1] | None
 ```

crates/red_knot_python_semantic/resources/mdtest/narrow/issubclass.md

@@ -170,7 +170,8 @@ if issubclass(t, int):
 def issubclass(c, ci):
     return True
 
-def flag() -> bool: ...
+def flag() -> bool:
+    return True
 
 t = int if flag() else str
 if issubclass(t, int):
@@ -182,7 +183,8 @@ if issubclass(t, int):
 ```py
 issubclass_alias = issubclass
 
-def flag() -> bool: ...
+def flag() -> bool:
+    return True
 
 t = int if flag() else str
 if issubclass_alias(t, int):
@@ -194,7 +196,8 @@ if issubclass_alias(t, int):
 ```py
 from builtins import issubclass as imported_issubclass
 
-def flag() -> bool: ...
+def flag() -> bool:
+    return True
 
 t = int if flag() else str
 if imported_issubclass(t, int):
@@ -206,7 +209,8 @@ if imported_issubclass(t, int):
 ```py
 from typing import Any
 
-def flag() -> bool: ...
+def flag() -> bool:
+    return True
 
 t = int if flag() else str
 
@@ -229,7 +233,8 @@ if issubclass(t, Any):
 ### Do not narrow if there are keyword arguments
 
 ```py
-def flag() -> bool: ...
+def flag() -> bool:
+    return True
 
 t = int if flag() else str
 

crates/red_knot_python_semantic/resources/mdtest/narrow/match.md

@@ -20,7 +20,8 @@ def _(flag: bool):
 ## Class patterns
 
 ```py
-def get_object() -> object: ...
+def get_object() -> object:
+    return object()
 
 class A: ...
 class B: ...
@@ -42,10 +43,12 @@ reveal_type(x)  # revealed: object
 ## Class pattern with guard
 
 ```py
-def get_object() -> object: ...
+def get_object() -> object:
+    return object()
 
 class A:
-    def y() -> int: ...
+    def y() -> int:
+        return 1
 
 class B: ...
 

crates/red_knot_python_semantic/resources/mdtest/narrow/truthiness.md

@@ -233,16 +233,20 @@ reveal_type(y)  # revealed: A
 from typing import Literal
 
 class MetaAmbiguous(type):
-    def __bool__(self) -> bool: ...
+    def __bool__(self) -> bool:
+        return True
 
 class MetaFalsy(type):
-    def __bool__(self) -> Literal[False]: ...
+    def __bool__(self) -> Literal[False]:
+        return False
 
 class MetaTruthy(type):
-    def __bool__(self) -> Literal[True]: ...
+    def __bool__(self) -> Literal[True]:
+        return True
 
 class MetaDeferred(type):
-    def __bool__(self) -> MetaAmbiguous: ...
+    def __bool__(self) -> MetaAmbiguous:
+        return MetaAmbiguous()
 
 class AmbiguousClass(metaclass=MetaAmbiguous): ...
 class FalsyClass(metaclass=MetaFalsy): ...
@@ -300,20 +304,24 @@ def _(x: bool | str):
     reveal_type(x and A())  # revealed: Literal[False] | str & ~AlwaysTruthy | A
 
 class Falsy:
-    def __bool__(self) -> Literal[False]: ...
+    def __bool__(self) -> Literal[False]:
+        return False
 
 class Truthy:
-    def __bool__(self) -> Literal[True]: ...
+    def __bool__(self) -> Literal[True]:
+        return True
 
 def _(x: Falsy | Truthy):
     reveal_type(x or A())  # revealed: Truthy | A
     reveal_type(x and A())  # revealed: Falsy | A
 
 class MetaFalsy(type):
-    def __bool__(self) -> Literal[False]: ...
+    def __bool__(self) -> Literal[False]:
+        return False
 
 class MetaTruthy(type):
-    def __bool__(self) -> Literal[True]: ...
+    def __bool__(self) -> Literal[True]:
+        return True
 
 class FalsyClass(metaclass=MetaFalsy): ...
 class TruthyClass(metaclass=MetaTruthy): ...

crates/red_knot_python_semantic/resources/mdtest/narrow/type.md

@@ -88,7 +88,7 @@ def _(x: str | int):
 
 ```py
 def _(x: str | int):
-    # TODO: we could issue a diagnostic here
+    # error: [no-matching-overload] "No overload of class `type` matches arguments"
     if type(object=x) is str:
         reveal_type(x)  # revealed: str | int
 ```

crates/red_knot_python_semantic/resources/mdtest/narrow/while.md

@@ -9,7 +9,8 @@ is retained after the loop.
 ## Basic `while` loop
 
 ```py
-def next_item() -> int | None: ...
+def next_item() -> int | None:
+    return 1
 
 x = next_item()
 
@@ -23,7 +24,8 @@ reveal_type(x)  # revealed: None
 ## `while` loop with `else`
 
 ```py
-def next_item() -> int | None: ...
+def next_item() -> int | None:
+    return 1
 
 x = next_item()
 
@@ -41,7 +43,8 @@ reveal_type(x)  # revealed: None
 ```py
 from typing import Literal
 
-def next_item() -> Literal[1, 2, 3]: ...
+def next_item() -> Literal[1, 2, 3]:
+    raise NotImplementedError
 
 x = next_item()
 

crates/red_knot_python_semantic/resources/mdtest/protocols.md

@@ -13,3 +13,13 @@ def _(some_int: int, some_literal_int: Literal[1], some_indexable: SupportsIndex
     b: SupportsIndex = some_literal_int
     c: SupportsIndex = some_indexable
 ```
+
+## Invalid
+
+```py
+from typing import Protocol
+
+# error: [invalid-type-form] "`typing.Protocol` is not allowed in type expressions"
+def f(x: Protocol) -> None:
+    reveal_type(x)  # revealed: Unknown
+```

crates/red_knot_python_semantic/resources/mdtest/slots.md

@@ -113,6 +113,24 @@ class D(B, A): ...  # fine
 class E(B, C, A): ...  # fine
 ```
 
+## Post-hoc modifications
+
+```py
+class A:
+    __slots__ = ()
+    __slots__ += ("a", "b")
+
+reveal_type(A.__slots__)  # revealed: tuple[Literal["a"], Literal["b"]]
+
+class B:
+    __slots__ = ("c", "d")
+
+class C(
+    A,  # error: [incompatible-slots]
+    B,  # error: [incompatible-slots]
+): ...
+```
+
 ## False negatives
 
 ### Possibly unbound
@@ -160,22 +178,6 @@ class B:
 class C(A, B): ...
 ```
 
-### Post-hoc modifications
-
-```py
-class A:
-    __slots__ = ()
-    __slots__ += ("a", "b")
-
-reveal_type(A.__slots__)  # revealed: @Todo(return type of decorated function)
-
-class B:
-    __slots__ = ("c", "d")
-
-# False negative: [incompatible-slots]
-class C(A, B): ...
-```
-
 ### Built-ins with implicit layouts
 
 ```py

crates/red_knot_python_semantic/resources/mdtest/snapshots/attribute_assignment.md_-_Attribute_assignment_-_Data_descriptors_-_Invalid_`__set__`_method_signature.snap

@@ -0,0 +1,39 @@
+---
+source: crates/red_knot_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: attribute_assignment.md - Attribute assignment - Data descriptors - Invalid `__set__` method signature
+mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attribute_assignment.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+ 1 | class WrongDescriptor:
+ 2 |     def __set__(self, instance: object, value: int, extra: int) -> None:
+ 3 |         pass
+ 4 | 
+ 5 | class C:
+ 6 |     attr: WrongDescriptor = WrongDescriptor()
+ 7 | 
+ 8 | instance = C()
+ 9 | 
+10 | # TODO: ideally, we would mention why this is an invalid assignment (wrong number of arguments for `__set__`)
+11 | instance.attr = 1  # error: [invalid-assignment]
+```
+
+# Diagnostics
+
+```
+error: lint:invalid-assignment
+  --> /src/mdtest_snippet.py:11:1
+   |
+10 | # TODO: ideally, we would mention why this is an invalid assignment (wrong number of arguments for `__set__`)
+11 | instance.attr = 1  # error: [invalid-assignment]
+   | ^^^^^^^^^^^^^ Invalid assignment to data descriptor attribute `attr` on type `C` with custom `__set__` method
+   |
+
+```

crates/red_knot_python_semantic/resources/mdtest/snapshots/attribute_assignment.md_-_Attribute_assignment_-_Data_descriptors_-_Invalid_argument_type.snap

@@ -0,0 +1,40 @@
+---
+source: crates/red_knot_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: attribute_assignment.md - Attribute assignment - Data descriptors - Invalid argument type
+mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attribute_assignment.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+ 1 | class Descriptor:
+ 2 |     def __set__(self, instance: object, value: int) -> None:
+ 3 |         pass
+ 4 | 
+ 5 | class C:
+ 6 |     attr: Descriptor = Descriptor()
+ 7 | 
+ 8 | instance = C()
+ 9 | instance.attr = 1  # fine
+10 | 
+11 | # TODO: ideally, we would mention why this is an invalid assignment (wrong argument type for `value` parameter)
+12 | instance.attr = "wrong"  # error: [invalid-assignment]
+```
+
+# Diagnostics
+
+```
+error: lint:invalid-assignment
+  --> /src/mdtest_snippet.py:12:1
+   |
+11 | # TODO: ideally, we would mention why this is an invalid assignment (wrong argument type for `value` parameter)
+12 | instance.attr = "wrong"  # error: [invalid-assignment]
+   | ^^^^^^^^^^^^^ Invalid assignment to data descriptor attribute `attr` on type `C` with custom `__set__` method
+   |
+
+```

crates/red_knot_python_semantic/resources/mdtest/snapshots/attribute_assignment.md_-_Attribute_assignment_-_Instance_attributes_with_class-level_defaults.snap

@@ -0,0 +1,51 @@
+---
+source: crates/red_knot_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: attribute_assignment.md - Attribute assignment - Instance attributes with class-level defaults
+mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attribute_assignment.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+1 | class C:
+2 |     attr: int = 0
+3 | 
+4 | instance = C()
+5 | instance.attr = 1  # fine
+6 | instance.attr = "wrong"  # error: [invalid-assignment]
+7 | 
+8 | C.attr = 1  # fine
+9 | C.attr = "wrong"  # error: [invalid-assignment]
+```
+
+# Diagnostics
+
+```
+error: lint:invalid-assignment
+ --> /src/mdtest_snippet.py:6:1
+  |
+4 | instance = C()
+5 | instance.attr = 1  # fine
+6 | instance.attr = "wrong"  # error: [invalid-assignment]
+  | ^^^^^^^^^^^^^ Object of type `Literal["wrong"]` is not assignable to attribute `attr` of type `int`
+7 |
+8 | C.attr = 1  # fine
+  |
+
+```
+
+```
+error: lint:invalid-assignment
+ --> /src/mdtest_snippet.py:9:1
+  |
+8 | C.attr = 1  # fine
+9 | C.attr = "wrong"  # error: [invalid-assignment]
+  | ^^^^^^ Object of type `Literal["wrong"]` is not assignable to attribute `attr` of type `int`
+  |
+
+```

crates/red_knot_python_semantic/resources/mdtest/snapshots/attribute_assignment.md_-_Attribute_assignment_-_Possibly-unbound_attributes.snap

@@ -0,0 +1,51 @@
+---
+source: crates/red_knot_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: attribute_assignment.md - Attribute assignment - Possibly-unbound attributes
+mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attribute_assignment.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+1 | def _(flag: bool) -> None:
+2 |     class C:
+3 |         if flag:
+4 |             attr: int = 0
+5 | 
+6 |     C.attr = 1  # error: [possibly-unbound-attribute]
+7 | 
+8 |     instance = C()
+9 |     instance.attr = 1  # error: [possibly-unbound-attribute]
+```
+
+# Diagnostics
+
+```
+warning: lint:possibly-unbound-attribute
+ --> /src/mdtest_snippet.py:6:5
+  |
+4 |             attr: int = 0
+5 |
+6 |     C.attr = 1  # error: [possibly-unbound-attribute]
+  |     ^^^^^^ Attribute `attr` on type `Literal[C]` is possibly unbound
+7 |
+8 |     instance = C()
+  |
+
+```
+
+```
+warning: lint:possibly-unbound-attribute
+ --> /src/mdtest_snippet.py:9:5
+  |
+8 |     instance = C()
+9 |     instance.attr = 1  # error: [possibly-unbound-attribute]
+  |     ^^^^^^^^^^^^^ Attribute `attr` on type `C` is possibly unbound
+  |
+
+```

crates/red_knot_python_semantic/resources/mdtest/snapshots/attribute_assignment.md_-_Attribute_assignment_-_Pure_instance_attributes.snap

@@ -0,0 +1,52 @@
+---
+source: crates/red_knot_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: attribute_assignment.md - Attribute assignment - Pure instance attributes
+mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attribute_assignment.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+1 | class C:
+2 |     def __init__(self):
+3 |         self.attr: int = 0
+4 | 
+5 | instance = C()
+6 | instance.attr = 1  # fine
+7 | instance.attr = "wrong"  # error: [invalid-assignment]
+8 | 
+9 | C.attr = 1  # error: [invalid-attribute-access]
+```
+
+# Diagnostics
+
+```
+error: lint:invalid-assignment
+ --> /src/mdtest_snippet.py:7:1
+  |
+5 | instance = C()
+6 | instance.attr = 1  # fine
+7 | instance.attr = "wrong"  # error: [invalid-assignment]
+  | ^^^^^^^^^^^^^ Object of type `Literal["wrong"]` is not assignable to attribute `attr` of type `int`
+8 |
+9 | C.attr = 1  # error: [invalid-attribute-access]
+  |
+
+```
+
+```
+error: lint:invalid-attribute-access
+ --> /src/mdtest_snippet.py:9:1
+  |
+7 | instance.attr = "wrong"  # error: [invalid-assignment]
+8 |
+9 | C.attr = 1  # error: [invalid-attribute-access]
+  | ^^^^^^ Cannot assign to instance attribute `attr` from the class object `Literal[C]`
+  |
+
+```

crates/red_knot_python_semantic/resources/mdtest/snapshots/attribute_assignment.md_-_Attribute_assignment_-_Setting_attributes_on_union_types.snap

@@ -0,0 +1,50 @@
+---
+source: crates/red_knot_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: attribute_assignment.md - Attribute assignment - Setting attributes on union types
+mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attribute_assignment.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+ 1 | def _(flag: bool) -> None:
+ 2 |     if flag:
+ 3 |         class C1:
+ 4 |             attr: int = 0
+ 5 | 
+ 6 |     else:
+ 7 |         class C1:
+ 8 |             attr: str = ""
+ 9 | 
+10 |     # TODO: The error message here could be improved to explain why the assignment fails.
+11 |     C1.attr = 1  # error: [invalid-assignment]
+12 | 
+13 |     class C2:
+14 |         if flag:
+15 |             attr: int = 0
+16 |         else:
+17 |             attr: str = ""
+18 | 
+19 |     # TODO: This should be an error
+20 |     C2.attr = 1
+```
+
+# Diagnostics
+
+```
+error: lint:invalid-assignment
+  --> /src/mdtest_snippet.py:11:5
+   |
+10 |     # TODO: The error message here could be improved to explain why the assignment fails.
+11 |     C1.attr = 1  # error: [invalid-assignment]
+   |     ^^^^^^^ Object of type `Literal[1]` is not assignable to attribute `attr` on type `Literal[C1, C1]`
+12 |
+13 |     class C2:
+   |
+
+```

crates/red_knot_python_semantic/resources/mdtest/snapshots/attribute_assignment.md_-_Attribute_assignment_-_Unknown_attributes.snap

@@ -0,0 +1,48 @@
+---
+source: crates/red_knot_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: attribute_assignment.md - Attribute assignment - Unknown attributes
+mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attribute_assignment.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+1 | class C: ...
+2 | 
+3 | C.non_existent = 1  # error: [unresolved-attribute]
+4 | 
+5 | instance = C()
+6 | instance.non_existent = 1  # error: [unresolved-attribute]
+```
+
+# Diagnostics
+
+```
+error: lint:unresolved-attribute
+ --> /src/mdtest_snippet.py:3:1
+  |
+1 | class C: ...
+2 |
+3 | C.non_existent = 1  # error: [unresolved-attribute]
+  | ^^^^^^^^^^^^^^ Unresolved attribute `non_existent` on type `Literal[C]`.
+4 |
+5 | instance = C()
+  |
+
+```
+
+```
+error: lint:unresolved-attribute
+ --> /src/mdtest_snippet.py:6:1
+  |
+5 | instance = C()
+6 | instance.non_existent = 1  # error: [unresolved-attribute]
+  | ^^^^^^^^^^^^^^^^^^^^^ Unresolved attribute `non_existent` on type `C`.
+  |
+
+```