Move gate

.devcontainer/devcontainer.json

@@ -20,7 +20,7 @@
 			"extensions": [
 				"ms-python.python",
 				"rust-lang.rust-analyzer",
-				"fill-labs.dependi",
+				"serayuzgur.crates",
 				"tamasfe.even-better-toml",
 				"Swellaby.vscode-rust-test-adapter",
 				"charliermarsh.ruff"

.editorconfig

@@ -17,7 +17,4 @@ indent_size = 4
 trim_trailing_whitespace = false
 
 [*.md]
-max_line_length = 100
-
-[*.toml]
-indent_size = 4
+max_line_length = 100

.gitattributes

@@ -14,7 +14,5 @@ crates/ruff_python_parser/resources/invalid/re_lex_logical_token_mac_eol.py text
 
 crates/ruff_python_parser/resources/inline linguist-generated=true
 
-ruff.schema.json -diff linguist-generated=true text=auto eol=lf
-crates/ruff_python_ast/src/generated.rs -diff linguist-generated=true text=auto eol=lf
-crates/ruff_python_formatter/src/generated.rs -diff linguist-generated=true text=auto eol=lf
+ruff.schema.json linguist-generated=true text=auto eol=lf
 *.md.snap linguist-language=Markdown

.github/CODEOWNERS

@@ -9,15 +9,13 @@
 /crates/ruff_formatter/ @MichaReiser
 /crates/ruff_python_formatter/ @MichaReiser
 /crates/ruff_python_parser/ @MichaReiser @dhruvmanila
-/crates/ruff_annotate_snippets/ @BurntSushi
 
 # flake8-pyi
 /crates/ruff_linter/src/rules/flake8_pyi/ @AlexWaygood
 
-# Script for fuzzing the parser/red-knot etc.
-/python/py-fuzzer/ @AlexWaygood
+# Script for fuzzing the parser
+/scripts/fuzz-parser/ @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
+/crates/ruff_db/ @carljm @MichaReiser @AlexWaygood

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,12 @@
+<!--
+Thank you for taking the time to report an issue! We're glad to have you involved with Ruff.
+
+If you're filing a bug report, please consider including the following information:
+
+* List of keywords you searched for before creating this issue. Write them down here so that others can find this issue more easily and help provide feedback.
+  e.g. "RUF001", "unused variable", "Jupyter notebook"
+* A minimal code snippet that reproduces the bug.
+* The command you invoked (e.g., `ruff /path/to/file.py --fix`), ideally including the `--isolated` flag.
+* The current Ruff settings (any relevant sections from your `pyproject.toml`).
+* The current Ruff version (`ruff --version`).
+-->

.github/actionlint.yaml

@@ -1,10 +0,0 @@
-# Configuration for the actionlint tool, which we run via pre-commit
-# to verify the correctness of the syntax in our GitHub Actions workflows.
-
-self-hosted-runner:
-  # Various runners we use that aren't recognized out-of-the-box by actionlint:
-  labels:
-    - depot-ubuntu-latest-8
-    - depot-ubuntu-22.04-16
-    - github-windows-2025-x86_64-8
-    - github-windows-2025-x86_64-16

.github/renovate.json5

@@ -8,32 +8,15 @@
   semanticCommits: "disabled",
   separateMajorMinor: false,
   prHourlyLimit: 10,
-  enabledManagers: ["github-actions", "pre-commit", "cargo", "pep621", "pip_requirements", "npm"],
+  enabledManagers: ["github-actions", "pre-commit", "cargo", "pep621", "npm"],
   cargo: {
     // See https://docs.renovatebot.com/configuration-options/#rangestrategy
     rangeStrategy: "update-lockfile",
   },
   pep621: {
-    // The default for this package manager is to only search for `pyproject.toml` files
-    // found at the repository root: https://docs.renovatebot.com/modules/manager/pep621/#file-matching
     fileMatch: ["^(python|scripts)/.*pyproject\\.toml$"],
   },
-  pip_requirements: {
-    // The default for this package manager is to run on all requirements.txt files:
-    // https://docs.renovatebot.com/modules/manager/pip_requirements/#file-matching
-    // `fileMatch` doesn't work for excluding files; to exclude `requirements.txt` files
-    // outside the `doc/` directory, we instead have to use `ignorePaths`. Unlike `fileMatch`,
-    // which takes a regex string, `ignorePaths` takes a glob string, so we have to use
-    // a "negative glob pattern".
-    // See:
-    // - https://docs.renovatebot.com/modules/manager/#ignoring-files-that-match-the-default-filematch
-    // - https://docs.renovatebot.com/configuration-options/#ignorepaths
-    // - https://docs.renovatebot.com/string-pattern-matching/#negative-matching
-    ignorePaths: ["!docs/requirements*.txt"]
-  },
   npm: {
-    // The default for this package manager is to only search for `package.json` files
-    // found at the repository root: https://docs.renovatebot.com/modules/manager/npm/#file-matching
     fileMatch: ["^playground/.*package\\.json$"],
   },
   "pre-commit": {
@@ -45,7 +28,7 @@
       groupName: "Artifact GitHub Actions dependencies",
       matchManagers: ["github-actions"],
       matchDatasources: ["gitea-tags", "github-tags"],
-      matchPackageNames: ["actions/.*-artifact"],
+      matchPackagePatterns: ["actions/.*-artifact"],
       description: "Weekly update of artifact-related GitHub Actions dependencies",
     },
     {
@@ -61,18 +44,10 @@
     {
       // Disable updates of `zip-rs`; intentionally pinned for now due to ownership change
       // See: https://github.com/astral-sh/uv/issues/3642
-      matchPackageNames: ["zip"],
+      matchPackagePatterns: ["zip"],
       matchManagers: ["cargo"],
       enabled: false,
     },
-    {
-      // `mkdocs-material` requires a manual update to keep the version in sync
-      // with `mkdocs-material-insider`.
-      // See: https://squidfunk.github.io/mkdocs-material/insiders/upgrade/
-      matchManagers: ["pip_requirements"],
-      matchPackageNames: ["mkdocs-material"],
-      enabled: false,
-    },
     {
       groupName: "pre-commit dependencies",
       matchManagers: ["pre-commit"],
@@ -87,13 +62,13 @@
     {
       groupName: "Monaco",
       matchManagers: ["npm"],
-      matchPackageNames: ["monaco"],
+      matchPackagePatterns: ["monaco"],
       description: "Weekly update of the Monaco editor",
     },
     {
       groupName: "strum",
       matchManagers: ["cargo"],
-      matchPackageNames: ["strum"],
+      matchPackagePatterns: ["strum"],
       description: "Weekly update of strum dependencies",
     },
     {

.github/workflows/build-binaries.yml

@@ -40,7 +40,6 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
-          persist-credentials: false
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
@@ -53,9 +52,9 @@ jobs:
           args: --out dist
       - name: "Test sdist"
         run: |
-          pip install dist/"${PACKAGE_NAME}"-*.tar.gz --force-reinstall
-          "${MODULE_NAME}" --help
-          python -m "${MODULE_NAME}" --help
+          pip install dist/${{ env.PACKAGE_NAME }}-*.tar.gz --force-reinstall
+          ${{ env.MODULE_NAME }} --help
+          python -m ${{ env.MODULE_NAME }} --help
       - name: "Upload sdist"
         uses: actions/upload-artifact@v4
         with:
@@ -64,12 +63,11 @@ jobs:
 
   macos-x86_64:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
-    runs-on: macos-14
+    runs-on: macos-12
     steps:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
-          persist-credentials: false
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
@@ -111,7 +109,6 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
-          persist-credentials: false
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
@@ -125,7 +122,7 @@ jobs:
           args: --release --locked --out dist
       - name: "Test wheel - aarch64"
         run: |
-          pip install dist/"${PACKAGE_NAME}"-*.whl --force-reinstall
+          pip install dist/${{ env.PACKAGE_NAME }}-*.whl --force-reinstall
           ruff --help
           python -m ruff --help
       - name: "Upload wheels"
@@ -167,7 +164,6 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
-          persist-credentials: false
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
@@ -186,9 +182,9 @@ jobs:
         if: ${{ !startsWith(matrix.platform.target, 'aarch64') }}
         shell: bash
         run: |
-          python -m pip install dist/"${PACKAGE_NAME}"-*.whl --force-reinstall
-          "${MODULE_NAME}" --help
-          python -m "${MODULE_NAME}" --help
+          python -m pip install dist/${{ env.PACKAGE_NAME }}-*.whl --force-reinstall
+          ${{ env.MODULE_NAME }} --help
+          python -m ${{ env.MODULE_NAME }} --help
       - name: "Upload wheels"
         uses: actions/upload-artifact@v4
         with:
@@ -220,7 +216,6 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
-          persist-credentials: false
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
@@ -236,9 +231,9 @@ jobs:
       - name: "Test wheel"
         if: ${{ startsWith(matrix.target, 'x86_64') }}
         run: |
-          pip install dist/"${PACKAGE_NAME}"-*.whl --force-reinstall
-          "${MODULE_NAME}" --help
-          python -m "${MODULE_NAME}" --help
+          pip install dist/${{ env.PACKAGE_NAME }}-*.whl --force-reinstall
+          ${{ env.MODULE_NAME }} --help
+          python -m ${{ env.MODULE_NAME }} --help
       - name: "Upload wheels"
         uses: actions/upload-artifact@v4
         with:
@@ -295,7 +290,6 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
-          persist-credentials: false
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
@@ -360,7 +354,6 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
-          persist-credentials: false
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
@@ -426,7 +419,6 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
-          persist-credentials: false
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}

.github/workflows/build-docker.yml

@@ -17,26 +17,16 @@ on:
     paths:
       - .github/workflows/build-docker.yml
 
-env:
-  RUFF_BASE_IMG: ghcr.io/${{ github.repository_owner }}/ruff
-
 jobs:
-  docker-build:
-    name: Build Docker image (ghcr.io/astral-sh/ruff) for ${{ matrix.platform }}
+  docker-publish:
+    name: Build Docker image (ghcr.io/astral-sh/ruff)
     runs-on: ubuntu-latest
     environment:
       name: release
-    strategy:
-      fail-fast: false
-      matrix:
-        platform:
-          - linux/amd64
-          - linux/arm64
     steps:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
-          persist-credentials: false
 
       - uses: docker/setup-buildx-action@v3
 
@@ -46,254 +36,33 @@ jobs:
           username: ${{ github.repository_owner }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ghcr.io/astral-sh/ruff
+
       - name: Check tag consistency
         if: ${{ inputs.plan != '' && !fromJson(inputs.plan).announcement_tag_is_implicit }}
-        env:
-          TAG: ${{ inputs.plan != '' && fromJson(inputs.plan).announcement_tag || 'dry-run' }}
         run: |
           version=$(grep "version = " pyproject.toml | sed -e 's/version = "\(.*\)"/\1/g')
-          if [ "${TAG}" != "${version}" ]; then
+          if [ "${{ fromJson(inputs.plan).announcement_tag }}" != "${version}" ]; then
             echo "The input tag does not match the version from pyproject.toml:" >&2
-            echo "${TAG}" >&2
+            echo "${{ fromJson(inputs.plan).announcement_tag }}" >&2
             echo "${version}" >&2
             exit 1
           else
             echo "Releasing ${version}"
           fi
 
-      - name: Extract metadata (tags, labels) for Docker
-        id: meta
-        uses: docker/metadata-action@v5
-        with:
-          images: ${{ env.RUFF_BASE_IMG }}
-          # Defining this makes sure the org.opencontainers.image.version OCI label becomes the actual release version and not the branch name
-          tags: |
-            type=raw,value=dry-run,enable=${{ inputs.plan == '' || fromJson(inputs.plan).announcement_tag_is_implicit }}
-            type=pep440,pattern={{ version }},value=${{ inputs.plan != '' && fromJson(inputs.plan).announcement_tag || 'dry-run' }},enable=${{ inputs.plan != '' && !fromJson(inputs.plan).announcement_tag_is_implicit }}
-
-      - name: Normalize Platform Pair (replace / with -)
-        run: |
-          platform=${{ matrix.platform }}
-          echo "PLATFORM_TUPLE=${platform//\//-}" >> "$GITHUB_ENV"
-
-      # 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
-        with:
-          context: .
-          platforms: ${{ matrix.platform }}
-          cache-from: type=gha,scope=ruff-${{ env.PLATFORM_TUPLE }}
-          cache-to: type=gha,mode=min,scope=ruff-${{ env.PLATFORM_TUPLE }}
-          labels: ${{ steps.meta.outputs.labels }}
-          outputs: type=image,name=${{ env.RUFF_BASE_IMG }},push-by-digest=true,name-canonical=true,push=${{ inputs.plan != '' && !fromJson(inputs.plan).announcement_tag_is_implicit }}
-
-      - name: Export digests
-        env:
-          digest: ${{ steps.build.outputs.digest }}
-        run: |
-          mkdir -p /tmp/digests
-          touch "/tmp/digests/${digest#sha256:}"
-
-      - name: Upload digests
-        uses: actions/upload-artifact@v4
-        with:
-          name: digests-${{ env.PLATFORM_TUPLE }}
-          path: /tmp/digests/*
-          if-no-files-found: error
-          retention-days: 1
-
-  docker-publish:
-    name: Publish Docker image (ghcr.io/astral-sh/ruff)
-    runs-on: ubuntu-latest
-    environment:
-      name: release
-    needs:
-      - docker-build
-    if: ${{ inputs.plan != '' && !fromJson(inputs.plan).announcement_tag_is_implicit }}
-    steps:
-      - name: Download digests
-        uses: actions/download-artifact@v4
-        with:
-          path: /tmp/digests
-          pattern: digests-*
-          merge-multiple: true
-
-      - uses: docker/setup-buildx-action@v3
-
-      - name: Extract metadata (tags, labels) for Docker
-        id: meta
-        uses: docker/metadata-action@v5
-        with:
-          images: ${{ env.RUFF_BASE_IMG }}
-          # Order is on purpose such that the label org.opencontainers.image.version has the first pattern with the full version
-          tags: |
-            type=pep440,pattern={{ version }},value=${{ fromJson(inputs.plan).announcement_tag }}
-            type=pep440,pattern={{ major }}.{{ minor }},value=${{ fromJson(inputs.plan).announcement_tag }}
-
-      - uses: docker/login-action@v3
-        with:
-          registry: ghcr.io
-          username: ${{ github.repository_owner }}
-          password: ${{ secrets.GITHUB_TOKEN }}
-
-      # Adapted from https://docs.docker.com/build/ci/github-actions/multi-platform/
-      - name: Create manifest list and push
-        working-directory: /tmp/digests
-        # The jq command expands the docker/metadata json "tags" array entry to `-t tag1 -t tag2 ...` for each tag in the array
-        # The printf will expand the base image with the `<RUFF_BASE_IMG>@sha256:<sha256> ...` for each sha256 in the directory
-        # The final command becomes `docker buildx imagetools create -t tag1 -t tag2 ... <RUFF_BASE_IMG>@sha256:<sha256_1> <RUFF_BASE_IMG>@sha256:<sha256_2> ...`
-        run: |
-          # shellcheck disable=SC2046
-          docker buildx imagetools create \
-            $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
-            $(printf "${RUFF_BASE_IMG}@sha256:%s " *)
-
-  docker-publish-extra:
-    name: Publish additional Docker image based on ${{ matrix.image-mapping }}
-    runs-on: ubuntu-latest
-    environment:
-      name: release
-    needs:
-      - docker-publish
-    if: ${{ inputs.plan != '' && !fromJson(inputs.plan).announcement_tag_is_implicit }}
-    strategy:
-      fail-fast: false
-      matrix:
-        # 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
-          - debian:bookworm-slim,bookworm-slim,debian-slim
-          - buildpack-deps:bookworm,bookworm,debian
-    steps:
-      - uses: docker/setup-buildx-action@v3
-
-      - uses: docker/login-action@v3
-        with:
-          registry: ghcr.io
-          username: ${{ github.repository_owner }}
-          password: ${{ secrets.GITHUB_TOKEN }}
-
-      - name: Generate Dynamic Dockerfile Tags
-        shell: bash
-        env:
-          TAG_VALUE: ${{ fromJson(inputs.plan).announcement_tag }}
-        run: |
-          set -euo pipefail
-
-          # Extract the image and tags from the matrix variable
-          IFS=',' read -r BASE_IMAGE BASE_TAGS <<< "${{ matrix.image-mapping }}"
-
-          # Generate Dockerfile content
-          cat <<EOF > Dockerfile
-          FROM ${BASE_IMAGE}
-          COPY --from=${RUFF_BASE_IMG}:latest /ruff /usr/local/bin/ruff
-          ENTRYPOINT []
-          CMD ["/usr/local/bin/ruff"]
-          EOF
-
-          # Initialize a variable to store all tag docker metadata patterns
-          TAG_PATTERNS=""
-
-          # Loop through all base tags and append its docker metadata pattern to the list
-          # Order is on purpose such that the label org.opencontainers.image.version has the first pattern with the full version
-          IFS=','; for TAG in ${BASE_TAGS}; do
-            TAG_PATTERNS="${TAG_PATTERNS}type=pep440,pattern={{ version }},suffix=-${TAG},value=${TAG_VALUE}\n"
-            TAG_PATTERNS="${TAG_PATTERNS}type=pep440,pattern={{ major }}.{{ minor }},suffix=-${TAG},value=${TAG_VALUE}\n"
-            TAG_PATTERNS="${TAG_PATTERNS}type=raw,value=${TAG}\n"
-          done
-
-          # Remove the trailing newline from the pattern list
-          TAG_PATTERNS="${TAG_PATTERNS%\\n}"
-
-          # Export image cache name
-          echo "IMAGE_REF=${BASE_IMAGE//:/-}" >> "$GITHUB_ENV"
-
-          # Export tag patterns using the multiline env var syntax
-          {
-            echo "TAG_PATTERNS<<EOF"
-            echo -e "${TAG_PATTERNS}"
-            echo EOF
-          } >> "$GITHUB_ENV"
-
-      - name: Extract metadata (tags, labels) for Docker
-        id: meta
-        uses: docker/metadata-action@v5
-        # ghcr.io prefers index level annotations
-        env:
-          DOCKER_METADATA_ANNOTATIONS_LEVELS: index
-        with:
-          images: ${{ env.RUFF_BASE_IMG }}
-          flavor: |
-            latest=false
-          tags: |
-            ${{ env.TAG_PATTERNS }}
-
-      - name: Build and push
+      - name: "Build and push Docker image"
         uses: docker/build-push-action@v6
         with:
           context: .
           platforms: linux/amd64,linux/arm64
-          # We do not really need to cache here as the Dockerfile is tiny
-          #cache-from: type=gha,scope=ruff-${{ env.IMAGE_REF }}
-          #cache-to: type=gha,mode=min,scope=ruff-${{ env.IMAGE_REF }}
-          push: true
-          tags: ${{ steps.meta.outputs.tags }}
+          # Reuse the builder
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+          push: ${{ inputs.plan != '' && !fromJson(inputs.plan).announcement_tag_is_implicit }}
+          tags: ghcr.io/astral-sh/ruff:latest,ghcr.io/astral-sh/ruff:${{ (inputs.plan != '' && fromJson(inputs.plan).announcement_tag) || 'dry-run' }}
           labels: ${{ steps.meta.outputs.labels }}
-          annotations: ${{ steps.meta.outputs.annotations }}
-
-  # This is effectively a duplicate of `docker-publish` to make https://github.com/astral-sh/ruff/pkgs/container/ruff
-  # show the ruff base image first since GitHub always shows the last updated image digests
-  # This works by annotating the original digests (previously non-annotated) which triggers an update to ghcr.io
-  docker-republish:
-    name: Annotate Docker image (ghcr.io/astral-sh/ruff)
-    runs-on: ubuntu-latest
-    environment:
-      name: release
-    needs:
-      - docker-publish-extra
-    if: ${{ inputs.plan != '' && !fromJson(inputs.plan).announcement_tag_is_implicit }}
-    steps:
-      - name: Download digests
-        uses: actions/download-artifact@v4
-        with:
-          path: /tmp/digests
-          pattern: digests-*
-          merge-multiple: true
-
-      - uses: docker/setup-buildx-action@v3
-
-      - name: Extract metadata (tags, labels) for Docker
-        id: meta
-        uses: docker/metadata-action@v5
-        env:
-          DOCKER_METADATA_ANNOTATIONS_LEVELS: index
-        with:
-          images: ${{ env.RUFF_BASE_IMG }}
-          # Order is on purpose such that the label org.opencontainers.image.version has the first pattern with the full version
-          tags: |
-            type=pep440,pattern={{ version }},value=${{ fromJson(inputs.plan).announcement_tag }}
-            type=pep440,pattern={{ major }}.{{ minor }},value=${{ fromJson(inputs.plan).announcement_tag }}
-
-      - uses: docker/login-action@v3
-        with:
-          registry: ghcr.io
-          username: ${{ github.repository_owner }}
-          password: ${{ secrets.GITHUB_TOKEN }}
-
-      # Adapted from https://docs.docker.com/build/ci/github-actions/multi-platform/
-      - name: Create manifest list and push
-        working-directory: /tmp/digests
-        # The readarray part is used to make sure the quoting and special characters are preserved on expansion (e.g. spaces)
-        # The jq command expands the docker/metadata json "tags" array entry to `-t tag1 -t tag2 ...` for each tag in the array
-        # The printf will expand the base image with the `<RUFF_BASE_IMG>@sha256:<sha256> ...` for each sha256 in the directory
-        # The final command becomes `docker buildx imagetools create -t tag1 -t tag2 ... <RUFF_BASE_IMG>@sha256:<sha256_1> <RUFF_BASE_IMG>@sha256:<sha256_2> ...`
-        run: |
-          readarray -t lines <<< "$DOCKER_METADATA_OUTPUT_ANNOTATIONS"; annotations=(); for line in "${lines[@]}"; do annotations+=(--annotation "$line"); done
-
-          # shellcheck disable=SC2046
-          docker buildx imagetools create \
-            "${annotations[@]}" \
-            $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
-            $(printf "${RUFF_BASE_IMG}@sha256:%s " *)

.github/workflows/ci.yaml

@@ -16,7 +16,7 @@ env:
   CARGO_TERM_COLOR: always
   RUSTUP_MAX_RETRIES: 10
   PACKAGE_NAME: ruff
-  PYTHON_VERSION: "3.12"
+  PYTHON_VERSION: "3.11"
 
 jobs:
   determine_changes:
@@ -32,15 +32,12 @@ jobs:
       # Flag that is raised when any code is changed
       # This is superset of the linter and formatter
       code: ${{ steps.changed.outputs.code_any_changed }}
-      # Flag that is raised when any code that affects the fuzzer is changed
-      fuzz: ${{ steps.changed.outputs.fuzz_any_changed }}
     steps:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-          persist-credentials: false
 
-      - uses: tj-actions/changed-files@v45
+      - uses: tj-actions/changed-files@v44
         id: changed
         with:
           files_yaml: |
@@ -52,7 +49,7 @@ jobs:
               - crates/ruff_text_size/**
               - crates/ruff_python_ast/**
               - crates/ruff_python_parser/**
-              - python/py-fuzzer/**
+              - scripts/fuzz-parser/**
               - .github/workflows/ci.yaml
 
             linter:
@@ -82,15 +79,9 @@ jobs:
               - python/**
               - .github/workflows/ci.yaml
 
-            fuzz:
-              - fuzz/Cargo.toml
-              - fuzz/Cargo.lock
-              - fuzz/fuzz_targets/**
-
             code:
               - "**/*"
               - "!**/*.md"
-              - "crates/red_knot_python_semantic/resources/mdtest/**/*.md"
               - "!docs/**"
               - "!assets/**"
 
@@ -100,8 +91,6 @@ jobs:
     timeout-minutes: 10
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup component add rustfmt
       - run: cargo fmt --all --check
@@ -114,8 +103,6 @@ jobs:
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - name: "Install Rust toolchain"
         run: |
           rustup component add clippy
@@ -124,18 +111,16 @@ jobs:
       - name: "Clippy"
         run: cargo clippy --workspace --all-targets --all-features --locked -- -D warnings
       - name: "Clippy (wasm)"
-        run: cargo clippy -p ruff_wasm -p red_knot_wasm --target wasm32-unknown-unknown --all-features --locked -- -D warnings
+        run: cargo clippy -p ruff_wasm --target wasm32-unknown-unknown --all-features --locked -- -D warnings
 
   cargo-test-linux:
     name: "cargo test (linux)"
-    runs-on: depot-ubuntu-22.04-16
+    runs-on: ubuntu-latest
     needs: determine_changes
     if: ${{ needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main' }}
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
@@ -157,13 +142,6 @@ jobs:
 
       # Check for broken links in the documentation.
       - run: cargo doc --all --no-deps
-        env:
-          RUSTDOCFLAGS: "-D warnings"
-      # Use --document-private-items so that all our doc comments are kept in
-      # sync, not just public items. Eventually we should do this for all
-      # crates; for now add crates here as they are warning-clean to prevent
-      # regression.
-      - run: cargo doc --no-deps -p red_knot_python_semantic -p red_knot -p red_knot_test -p ruff_db --document-private-items
         env:
           # Setting RUSTDOCFLAGS because `cargo doc --check` isn't yet implemented (https://github.com/rust-lang/cargo/issues/10025).
           RUSTDOCFLAGS: "-D warnings"
@@ -172,45 +150,14 @@ jobs:
           name: ruff
           path: target/debug/ruff
 
-  cargo-test-linux-release:
-    name: "cargo test (linux, release)"
-    runs-on: depot-ubuntu-22.04-16
-    needs: determine_changes
-    if: ${{ needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main' }}
-    timeout-minutes: 20
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
-      - 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
-        with:
-          tool: cargo-nextest
-      - name: "Install cargo insta"
-        uses: taiki-e/install-action@v2
-        with:
-          tool: cargo-insta
-      - uses: Swatinem/rust-cache@v2
-      - name: "Run tests"
-        shell: bash
-        env:
-          NEXTEST_PROFILE: "ci"
-        run: cargo insta test --release --all-features --unreferenced reject --test-runner nextest
-
   cargo-test-windows:
     name: "cargo test (windows)"
-    runs-on: github-windows-2025-x86_64-16
+    runs-on: windows-latest
     needs: determine_changes
     if: ${{ needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main' }}
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install cargo nextest"
@@ -235,37 +182,28 @@ jobs:
     timeout-minutes: 10
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup target add wasm32-unknown-unknown
       - uses: actions/setup-node@v4
         with:
-          node-version: 20
+          node-version: 18
           cache: "npm"
           cache-dependency-path: playground/package-lock.json
       - uses: jetli/wasm-pack-action@v0.4.0
-        with:
-          version: v0.13.1
       - uses: Swatinem/rust-cache@v2
-      - name: "Test ruff_wasm"
+      - name: "Run wasm-pack"
         run: |
           cd crates/ruff_wasm
           wasm-pack test --node
-      - name: "Test red_knot_wasm"
-        run: |
-          cd crates/red_knot_wasm
-          wasm-pack test --node
 
   cargo-build-release:
     name: "cargo build (release)"
     runs-on: macos-latest
-    if: ${{ github.ref == 'refs/heads/main' }}
+    needs: determine_changes
+    if: ${{ needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main' }}
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
@@ -282,17 +220,13 @@ jobs:
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - uses: SebRollen/toml-action@v1.2.0
         id: msrv
         with:
           file: "Cargo.toml"
           field: "workspace.package.rust-version"
       - name: "Install Rust toolchain"
-        env:
-          MSRV: ${{ steps.msrv.outputs.value }}
-        run: rustup default "${MSRV}"
+        run: rustup default ${{ steps.msrv.outputs.value }}
       - name: "Install mold"
         uses: rui314/setup-mold@v1
       - name: "Install cargo nextest"
@@ -308,19 +242,16 @@ jobs:
         shell: bash
         env:
           NEXTEST_PROFILE: "ci"
-          MSRV: ${{ steps.msrv.outputs.value }}
-        run: cargo "+${MSRV}" insta test --all-features --unreferenced reject --test-runner nextest
+        run: cargo +${{ steps.msrv.outputs.value }} insta test --all-features --unreferenced reject --test-runner nextest
 
-  cargo-fuzz-build:
-    name: "cargo fuzz build"
+  cargo-fuzz:
+    name: "cargo fuzz"
     runs-on: ubuntu-latest
     needs: determine_changes
-    if: ${{ github.ref == 'refs/heads/main' || needs.determine_changes.outputs.fuzz == 'true' || needs.determine_changes.outputs.code == 'true' }}
+    if: ${{ needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main' }}
     timeout-minutes: 10
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup show
       - uses: Swatinem/rust-cache@v2
@@ -336,7 +267,7 @@ jobs:
       - run: cargo fuzz build -s none
 
   fuzz-parser:
-    name: "fuzz parser"
+    name: "Fuzz the parser"
     runs-on: ubuntu-latest
     needs:
       - cargo-test-linux
@@ -347,9 +278,13 @@ jobs:
       FORCE_COLOR: 1
     steps:
       - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
         with:
-          persist-credentials: false
-      - uses: astral-sh/setup-uv@v5
+          python-version: ${{ env.PYTHON_VERSION }}
+      - name: Install uv
+        run: curl -LsSf https://astral.sh/uv/install.sh | sh
+      - name: Install Python requirements
+        run: uv pip install -r scripts/fuzz-parser/requirements.txt --system
       - uses: actions/download-artifact@v4
         name: Download Ruff binary to test
         id: download-cached-binary
@@ -357,21 +292,11 @@ jobs:
           name: ruff
           path: ruff-to-test
       - name: Fuzz
-        env:
-          DOWNLOAD_PATH: ${{ steps.download-cached-binary.outputs.download-path }}
         run: |
           # Make executable, since artifact download doesn't preserve this
-          chmod +x "${DOWNLOAD_PATH}/ruff"
+          chmod +x ${{ steps.download-cached-binary.outputs.download-path }}/ruff
 
-          (
-            uvx \
-            --python="${PYTHON_VERSION}" \
-            --from=./python/py-fuzzer \
-            fuzz \
-            --test-executable="${DOWNLOAD_PATH}/ruff" \
-            --bin=ruff \
-            0-500
-          )
+          python scripts/fuzz-parser/fuzz.py 0-500 --test-executable ${{ steps.download-cached-binary.outputs.download-path }}/ruff
 
   scripts:
     name: "test scripts"
@@ -381,18 +306,10 @@ jobs:
     timeout-minutes: 5
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup component add rustfmt
       - uses: Swatinem/rust-cache@v2
-      # Run all code generation scripts, and verify that the current output is
-      # already checked into git.
-      - run: python crates/ruff_python_ast/generate.py
-      - run: python crates/ruff_python_formatter/generate.py
-      - run: test -z "$(git status --porcelain)"
-      # Verify that adding a plugin or rule produces clean code.
-      - run: ./scripts/add_rule.py --name DoTheThing --prefix F --code 999 --linter pyflakes
+      - run: ./scripts/add_rule.py --name DoTheThing --prefix PL --code C0999 --linter pylint
       - run: cargo check
       - run: cargo fmt --all --check
       - run: |
@@ -403,7 +320,7 @@ jobs:
 
   ecosystem:
     name: "ecosystem"
-    runs-on: depot-ubuntu-latest-8
+    runs-on: ubuntu-latest
     needs:
       - cargo-test-linux
       - determine_changes
@@ -413,8 +330,6 @@ jobs:
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
@@ -426,7 +341,7 @@ jobs:
           name: ruff
           path: target/debug
 
-      - uses: dawidd6/action-download-artifact@v7
+      - uses: dawidd6/action-download-artifact@v6
         name: Download baseline Ruff binary
         with:
           name: ruff
@@ -440,72 +355,64 @@ jobs:
 
       - name: Run `ruff check` stable ecosystem check
         if: ${{ needs.determine_changes.outputs.linter == 'true' }}
-        env:
-          DOWNLOAD_PATH: ${{ steps.ruff-target.outputs.download-path }}
         run: |
           # Make executable, since artifact download doesn't preserve this
-          chmod +x ./ruff "${DOWNLOAD_PATH}/ruff"
+          chmod +x ./ruff ${{ steps.ruff-target.outputs.download-path }}/ruff
 
           # Set pipefail to avoid hiding errors with tee
           set -eo pipefail
 
-          ruff-ecosystem check ./ruff "${DOWNLOAD_PATH}/ruff" --cache ./checkouts --output-format markdown | tee ecosystem-result-check-stable
+          ruff-ecosystem check ./ruff ${{ steps.ruff-target.outputs.download-path }}/ruff --cache ./checkouts --output-format markdown | tee ecosystem-result-check-stable
 
-          cat ecosystem-result-check-stable > "$GITHUB_STEP_SUMMARY"
+          cat ecosystem-result-check-stable > $GITHUB_STEP_SUMMARY
           echo "### Linter (stable)"  > ecosystem-result
           cat ecosystem-result-check-stable >> ecosystem-result
           echo "" >> ecosystem-result
 
       - name: Run `ruff check` preview ecosystem check
         if: ${{ needs.determine_changes.outputs.linter == 'true' }}
-        env:
-          DOWNLOAD_PATH: ${{ steps.ruff-target.outputs.download-path }}
         run: |
           # Make executable, since artifact download doesn't preserve this
-          chmod +x ./ruff "${DOWNLOAD_PATH}/ruff"
+          chmod +x ./ruff ${{ steps.ruff-target.outputs.download-path }}/ruff
 
           # Set pipefail to avoid hiding errors with tee
           set -eo pipefail
 
-          ruff-ecosystem check ./ruff "${DOWNLOAD_PATH}/ruff" --cache ./checkouts --output-format markdown --force-preview | tee ecosystem-result-check-preview
+          ruff-ecosystem check ./ruff ${{ steps.ruff-target.outputs.download-path }}/ruff --cache ./checkouts --output-format markdown --force-preview | tee ecosystem-result-check-preview
 
-          cat ecosystem-result-check-preview > "$GITHUB_STEP_SUMMARY"
+          cat ecosystem-result-check-preview > $GITHUB_STEP_SUMMARY
           echo "### Linter (preview)" >> ecosystem-result
           cat ecosystem-result-check-preview >> ecosystem-result
           echo "" >> ecosystem-result
 
       - name: Run `ruff format` stable ecosystem check
         if: ${{ needs.determine_changes.outputs.formatter == 'true' }}
-        env:
-          DOWNLOAD_PATH: ${{ steps.ruff-target.outputs.download-path }}
         run: |
           # Make executable, since artifact download doesn't preserve this
-          chmod +x ./ruff "${DOWNLOAD_PATH}/ruff"
+          chmod +x ./ruff ${{ steps.ruff-target.outputs.download-path }}/ruff
 
           # Set pipefail to avoid hiding errors with tee
           set -eo pipefail
 
-          ruff-ecosystem format ./ruff "${DOWNLOAD_PATH}/ruff" --cache ./checkouts --output-format markdown | tee ecosystem-result-format-stable
+          ruff-ecosystem format ./ruff ${{ steps.ruff-target.outputs.download-path }}/ruff --cache ./checkouts --output-format markdown | tee ecosystem-result-format-stable
 
-          cat ecosystem-result-format-stable > "$GITHUB_STEP_SUMMARY"
+          cat ecosystem-result-format-stable > $GITHUB_STEP_SUMMARY
           echo "### Formatter (stable)" >> ecosystem-result
           cat ecosystem-result-format-stable >> ecosystem-result
           echo "" >> ecosystem-result
 
       - name: Run `ruff format` preview ecosystem check
         if: ${{ needs.determine_changes.outputs.formatter == 'true' }}
-        env:
-          DOWNLOAD_PATH: ${{ steps.ruff-target.outputs.download-path }}
         run: |
           # Make executable, since artifact download doesn't preserve this
-          chmod +x ./ruff "${DOWNLOAD_PATH}/ruff"
+          chmod +x ./ruff ${{ steps.ruff-target.outputs.download-path }}/ruff
 
           # Set pipefail to avoid hiding errors with tee
           set -eo pipefail
 
-          ruff-ecosystem format ./ruff "${DOWNLOAD_PATH}/ruff" --cache ./checkouts --output-format markdown --force-preview | tee ecosystem-result-format-preview
+          ruff-ecosystem format ./ruff ${{ steps.ruff-target.outputs.download-path }}/ruff --cache ./checkouts --output-format markdown --force-preview | tee ecosystem-result-format-preview
 
-          cat ecosystem-result-format-preview > "$GITHUB_STEP_SUMMARY"
+          cat ecosystem-result-format-preview > $GITHUB_STEP_SUMMARY
           echo "### Formatter (preview)" >> ecosystem-result
           cat ecosystem-result-format-preview >> ecosystem-result
           echo "" >> ecosystem-result
@@ -533,8 +440,6 @@ jobs:
     if: ${{ needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main' }}
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - uses: cargo-bins/cargo-binstall@main
       - run: cargo binstall --no-confirm cargo-shear
       - run: cargo shear
@@ -545,8 +450,6 @@ jobs:
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
@@ -560,7 +463,7 @@ jobs:
           args: --out dist
       - name: "Test wheel"
         run: |
-          pip install --force-reinstall --find-links dist "${PACKAGE_NAME}"
+          pip install --force-reinstall --find-links dist ${{ env.PACKAGE_NAME }}
           ruff --help
           python -m ruff --help
       - name: "Remove wheels from cache"
@@ -572,8 +475,6 @@ jobs:
     timeout-minutes: 10
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
@@ -589,14 +490,13 @@ jobs:
           key: pre-commit-${{ hashFiles('.pre-commit-config.yaml') }}
       - name: "Run pre-commit"
         run: |
-          echo '```console' > "$GITHUB_STEP_SUMMARY"
+          echo '```console' > $GITHUB_STEP_SUMMARY
           # Enable color output for pre-commit and remove it for the summary
-          # Use --hook-stage=manual to enable slower pre-commit hooks that are skipped by default
-          SKIP=cargo-fmt,clippy,dev-generate-all pre-commit run --all-files --show-diff-on-failure --color=always --hook-stage=manual | \
-            tee >(sed -E 's/\x1B\[([0-9]{1,2}(;[0-9]{1,2})*)?[mGK]//g' >> "$GITHUB_STEP_SUMMARY") >&1
-          exit_code="${PIPESTATUS[0]}"
-          echo '```' >> "$GITHUB_STEP_SUMMARY"
-          exit "$exit_code"
+          SKIP=cargo-fmt,clippy,dev-generate-all pre-commit run --all-files --show-diff-on-failure --color=always | \
+            tee >(sed -E 's/\x1B\[([0-9]{1,2}(;[0-9]{1,2})*)?[mGK]//g' >> $GITHUB_STEP_SUMMARY) >&1
+          exit_code=${PIPESTATUS[0]}
+          echo '```' >> $GITHUB_STEP_SUMMARY
+          exit $exit_code
 
   docs:
     name: "mkdocs"
@@ -606,11 +506,7 @@ jobs:
       MKDOCS_INSIDERS_SSH_KEY_EXISTS: ${{ secrets.MKDOCS_INSIDERS_SSH_KEY != '' }}
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - uses: actions/setup-python@v5
-        with:
-          python-version: "3.13"
       - name: "Add SSH key"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS == 'true' }}
         uses: webfactory/ssh-agent@v0.9.0
@@ -618,15 +514,13 @@ jobs:
           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: Swatinem/rust-cache@v2
       - name: "Install Insiders dependencies"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS == 'true' }}
-        run: uv pip install -r docs/requirements-insiders.txt --system
+        run: pip install -r docs/requirements-insiders.txt
       - name: "Install dependencies"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS != 'true' }}
-        run: uv pip install -r docs/requirements.txt --system
+        run: pip install -r docs/requirements.txt
       - name: "Update README File"
         run: python scripts/transform_readme.py --target mkdocs
       - name: "Generate docs"
@@ -648,18 +542,16 @@ jobs:
     timeout-minutes: 10
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Cache rust"
         uses: Swatinem/rust-cache@v2
-      - name: "Run checks"
+      - name: "Formatter progress"
         run: scripts/formatter_ecosystem_checks.sh
       - name: "Github step summary"
-        run: cat target/formatter-ecosystem/stats.txt > "$GITHUB_STEP_SUMMARY"
+        run: cat target/progress_projects_stats.txt > $GITHUB_STEP_SUMMARY
       - name: "Remove checkouts from cache"
-        run: rm -r target/formatter-ecosystem
+        run: rm -r target/progress_projects
 
   check-ruff-lsp:
     name: "test ruff-lsp"
@@ -677,7 +569,6 @@ jobs:
       - uses: actions/checkout@v4
         name: "Download ruff-lsp source"
         with:
-          persist-credentials: false
           repository: "astral-sh/ruff-lsp"
 
       - uses: actions/setup-python@v5
@@ -696,27 +587,23 @@ jobs:
           just install
 
       - name: Run ruff-lsp tests
-        env:
-          DOWNLOAD_PATH: ${{ steps.ruff-target.outputs.download-path }}
         run: |
           # Setup development binary
           pip uninstall --yes ruff
-          chmod +x "${DOWNLOAD_PATH}/ruff"
-          export PATH="${DOWNLOAD_PATH}:${PATH}"
+          chmod +x ${{ steps.ruff-target.outputs.download-path }}/ruff
+          export PATH=${{ steps.ruff-target.outputs.download-path }}:$PATH
           ruff version
 
           just test
 
   benchmarks:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     needs: determine_changes
     if: ${{ github.repository == 'astral-sh/ruff' && (needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main') }}
     timeout-minutes: 20
     steps:
       - name: "Checkout Branch"
         uses: actions/checkout@v4
-        with:
-          persist-credentials: false
 
       - name: "Install Rust toolchain"
         run: rustup show
@@ -732,7 +619,7 @@ jobs:
         run: cargo codspeed build --features codspeed -p ruff_benchmark
 
       - name: "Run benchmarks"
-        uses: CodSpeedHQ/action@v3
+        uses: CodSpeedHQ/action@v2
         with:
           run: cargo codspeed run
           token: ${{ secrets.CODSPEED_TOKEN }}

.github/workflows/daily_fuzz.yaml

@@ -32,9 +32,13 @@ jobs:
     if: ${{ github.repository == 'astral-sh/ruff' || github.event_name != 'schedule' }}
     steps:
       - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
         with:
-          persist-credentials: false
-      - uses: astral-sh/setup-uv@v5
+          python-version: "3.12"
+      - name: Install uv
+        run: curl -LsSf https://astral.sh/uv/install.sh | sh
+      - name: Install Python requirements
+        run: uv pip install -r scripts/fuzz-parser/requirements.txt --system
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
@@ -45,17 +49,7 @@ jobs:
         # but this is outweighed by the fact that a release build takes *much* longer to compile in CI
         run: cargo build --locked
       - name: Fuzz
-        run: |
-          # shellcheck disable=SC2046
-          (
-            uvx \
-            --python=3.12 \
-            --from=./python/py-fuzzer \
-            fuzz \
-            --test-executable=target/debug/ruff \
-            --bin=ruff \
-            $(shuf -i 0-9999999999999999999 -n 1000)
-          )
+        run: python scripts/fuzz-parser/fuzz.py $(shuf -i 0-9999999999999999999 -n 1000) --test-executable target/debug/ruff
 
   create-issue-on-failure:
     name: Create an issue if the daily fuzz surfaced any bugs
@@ -73,6 +67,6 @@ jobs:
               owner: "astral-sh",
               repo: "ruff",
               title: `Daily parser fuzz failed on ${new Date().toDateString()}`,
-              body: "Run listed here: https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
+              body: "Runs listed here: https://github.com/astral-sh/ruff/actions/workflows/daily_fuzz.yml",
               labels: ["bug", "parser", "fuzzer"],
             })

.github/workflows/daily_property_tests.yaml

@@ -1,71 +0,0 @@
-name: Daily property test run
-
-on:
-  workflow_dispatch:
-  schedule:
-    - cron: "0 12 * * *"
-  pull_request:
-    paths:
-      - ".github/workflows/daily_property_tests.yaml"
-
-permissions:
-  contents: read
-
-concurrency:
-  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
-  cancel-in-progress: true
-
-env:
-  CARGO_INCREMENTAL: 0
-  CARGO_NET_RETRY: 10
-  CARGO_TERM_COLOR: always
-  RUSTUP_MAX_RETRIES: 10
-  FORCE_COLOR: 1
-
-jobs:
-  property_tests:
-    name: Property tests
-    runs-on: ubuntu-latest
-    timeout-minutes: 20
-    # Don't run the cron job on forks:
-    if: ${{ github.repository == 'astral-sh/ruff' || github.event_name != 'schedule' }}
-    steps:
-      - uses: actions/checkout@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
-      - 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.
-        run: cargo build --locked --release --package red_knot_python_semantic --tests
-      - name: Run property tests
-        shell: bash
-        run: |
-          export QUICKCHECK_TESTS=100000
-          for _ in {1..5}; do
-            cargo test --locked --release --package red_knot_python_semantic -- --ignored types::property_tests::stable
-          done
-
-  create-issue-on-failure:
-    name: Create an issue if the daily property test run surfaced any bugs
-    runs-on: ubuntu-latest
-    needs: property_tests
-    if: ${{ github.repository == 'astral-sh/ruff' && always() && github.event_name == 'schedule' && needs.property_tests.result == 'failure' }}
-    permissions:
-      issues: write
-    steps:
-      - uses: actions/github-script@v7
-        with:
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          script: |
-            await github.rest.issues.create({
-              owner: "astral-sh",
-              repo: "ruff",
-              title: `Daily property test run failed on ${new Date().toDateString()}`,
-              body: "Run listed here: https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              labels: ["bug", "red-knot", "testing"],
-            })

.github/workflows/pr-comment.yaml

@@ -10,29 +10,29 @@ on:
         description: The ecosystem workflow that triggers the workflow run
         required: true
 
+permissions:
+  pull-requests: write
+
 jobs:
   comment:
     runs-on: ubuntu-latest
-    permissions:
-      pull-requests: write
     steps:
-      - uses: dawidd6/action-download-artifact@v7
+      - uses: dawidd6/action-download-artifact@v6
         name: Download pull request number
         with:
           name: pr-number
           run_id: ${{ github.event.workflow_run.id ||  github.event.inputs.workflow_run_id }}
           if_no_artifact_found: ignore
-          allow_forks: true
 
       - name: Parse pull request number
         id: pr-number
         run: |
           if [[ -f pr-number ]]
           then
-            echo "pr-number=$(<pr-number)" >> "$GITHUB_OUTPUT"
+            echo "pr-number=$(<pr-number)" >> $GITHUB_OUTPUT
           fi
 
-      - uses: dawidd6/action-download-artifact@v7
+      - uses: dawidd6/action-download-artifact@v6
         name: "Download ecosystem results"
         id: download-ecosystem-result
         if: steps.pr-number.outputs.pr-number
@@ -43,7 +43,6 @@ jobs:
           path: pr/ecosystem
           workflow_conclusion: completed
           if_no_artifact_found: ignore
-          allow_forks: true
 
       - name: Generate comment content
         id: generate-comment
@@ -65,9 +64,9 @@ jobs:
           cat pr/ecosystem/ecosystem-result >> comment.txt
           echo "" >> comment.txt
 
-          echo 'comment<<EOF' >> "$GITHUB_OUTPUT"
-          cat comment.txt >> "$GITHUB_OUTPUT"
-          echo 'EOF' >> "$GITHUB_OUTPUT"
+          echo 'comment<<EOF' >> $GITHUB_OUTPUT
+          cat comment.txt >> $GITHUB_OUTPUT
+          echo 'EOF' >> $GITHUB_OUTPUT
 
       - name: Find existing comment
         uses: peter-evans/find-comment@v3

.github/workflows/publish-docs.yml

@@ -21,124 +21,42 @@ jobs:
   mkdocs:
     runs-on: ubuntu-latest
     env:
+      CF_API_TOKEN_EXISTS: ${{ secrets.CF_API_TOKEN != '' }}
       MKDOCS_INSIDERS_SSH_KEY_EXISTS: ${{ secrets.MKDOCS_INSIDERS_SSH_KEY != '' }}
     steps:
       - uses: actions/checkout@v4
         with:
           ref: ${{ inputs.ref }}
-          persist-credentials: true
-
       - uses: actions/setup-python@v5
-        with:
-          python-version: 3.12
-
-      - name: "Set docs version"
-        env:
-          version: ${{ (inputs.plan != '' && fromJson(inputs.plan).announcement_tag) || inputs.ref }}
-        run: |
-          # if version is missing, use 'latest'
-          if [ -z "$version" ]; then
-            echo "Using 'latest' as version"
-            version="latest"
-          fi
-
-          # Use version as display name for now
-          display_name="$version"
-
-          echo "version=$version" >> "$GITHUB_ENV"
-          echo "display_name=$display_name" >> "$GITHUB_ENV"
-
-      - name: "Set branch name"
-        run: |
-          timestamp="$(date +%s)"
-
-          # create branch_display_name from display_name by replacing all
-          # characters disallowed in git branch names with hyphens
-          branch_display_name="$(echo "${display_name}" | tr -c '[:alnum:]._' '-' | tr -s '-')"
-
-          echo "branch_name=update-docs-$branch_display_name-$timestamp" >> "$GITHUB_ENV"
-          echo "timestamp=$timestamp" >> "$GITHUB_ENV"
-
       - name: "Add SSH key"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS == 'true' }}
         uses: webfactory/ssh-agent@v0.9.0
         with:
           ssh-private-key: ${{ secrets.MKDOCS_INSIDERS_SSH_KEY }}
-
       - name: "Install Rust toolchain"
         run: rustup show
-
       - uses: Swatinem/rust-cache@v2
-
       - name: "Install Insiders dependencies"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS == 'true' }}
         run: pip install -r docs/requirements-insiders.txt
-
       - name: "Install dependencies"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS != 'true' }}
         run: pip install -r docs/requirements.txt
-
       - name: "Copy README File"
         run: |
           python scripts/transform_readme.py --target mkdocs
           python scripts/generate_mkdocs.py
-
       - name: "Build Insiders docs"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS == 'true' }}
         run: mkdocs build --strict -f mkdocs.insiders.yml
-
       - name: "Build docs"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS != 'true' }}
         run: mkdocs build --strict -f mkdocs.public.yml
-
-      - name: "Clone docs repo"
-        run: git clone https://${{ secrets.ASTRAL_DOCS_PAT }}@github.com/astral-sh/docs.git astral-docs
-
-      - name: "Copy docs"
-        run: rm -rf astral-docs/site/ruff && mkdir -p astral-docs/site && cp -r site/ruff astral-docs/site/
-
-      - name: "Commit docs"
-        working-directory: astral-docs
-        run: |
-          git config user.name "astral-docs-bot"
-          git config user.email "176161322+astral-docs-bot@users.noreply.github.com"
-
-          git checkout -b "${branch_name}"
-          git add site/ruff
-          git commit -m "Update ruff documentation for $version"
-
-      - name: "Create Pull Request"
-        working-directory: astral-docs
-        env:
-          GITHUB_TOKEN: ${{ secrets.ASTRAL_DOCS_PAT }}
-        run: |
-          # set the PR title
-          pull_request_title="Update ruff documentation for ${display_name}"
-
-          # Delete any existing pull requests that are open for this version
-          # by checking against pull_request_title because the new PR will
-          # supersede the old one.
-          gh pr list --state open --json title --jq '.[] | select(.title == "$pull_request_title") | .number' | \
-            xargs -I {} gh pr close {}
-
-          # push the branch to GitHub
-          git push origin "${branch_name}"
-
-          # create the PR
-          gh pr create \
-            --base=main \
-            --head="${branch_name}" \
-            --title="${pull_request_title}" \
-            --body="Automated documentation update for ${display_name}" \
-            --label="documentation"
-
-      - name: "Merge Pull Request"
-        if: ${{ inputs.plan != '' && !fromJson(inputs.plan).announcement_tag_is_implicit }}
-        working-directory: astral-docs
-        env:
-          GITHUB_TOKEN: ${{ secrets.ASTRAL_DOCS_PAT }}
-        run: |
-          # auto-merge the PR if the build was triggered by a release. Manual builds should be reviewed by a human.
-          # give the PR a few seconds to be created before trying to auto-merge it
-          sleep 10
-          gh pr merge --squash "${branch_name}"
+      - name: "Deploy to Cloudflare Pages"
+        if: ${{ env.CF_API_TOKEN_EXISTS == 'true' }}
+        uses: cloudflare/wrangler-action@v3.7.0
+        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 site --project-name=astral-docs --branch ${{ github.head_ref || 'main' }} --commit-hash ${GITHUB_SHA}

.github/workflows/publish-playground.yml

@@ -25,13 +25,11 @@ jobs:
       CF_API_TOKEN_EXISTS: ${{ secrets.CF_API_TOKEN != '' }}
     steps:
       - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup target add wasm32-unknown-unknown
       - uses: actions/setup-node@v4
         with:
-          node-version: 20
+          node-version: 18
           cache: "npm"
           cache-dependency-path: playground/package-lock.json
       - uses: jetli/wasm-pack-action@v0.4.0
@@ -49,7 +47,7 @@ jobs:
         working-directory: playground
       - name: "Deploy to Cloudflare Pages"
         if: ${{ env.CF_API_TOKEN_EXISTS == 'true' }}
-        uses: cloudflare/wrangler-action@v3.13.1
+        uses: cloudflare/wrangler-action@v3.7.0
         with:
           apiToken: ${{ secrets.CF_API_TOKEN }}
           accountId: ${{ secrets.CF_ACCOUNT_ID }}

.github/workflows/publish-pypi.yml

@@ -21,12 +21,14 @@ jobs:
       # For PyPI's trusted publishing.
       id-token: write
     steps:
-      - name: "Install uv"
-        uses: astral-sh/setup-uv@v5
       - uses: actions/download-artifact@v4
         with:
           pattern: wheels-*
           path: wheels
           merge-multiple: true
       - name: Publish to PyPi
-        run: uv publish -v wheels/*
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          skip-existing: true
+          packages-dir: wheels
+          verbose: true

.github/workflows/publish-wasm.yml

@@ -1,57 +0,0 @@
-# Build and publish ruff-api for wasm.
-#
-# Assumed to run as a subworkflow of .github/workflows/release.yml; specifically, as a publish
-# job within `cargo-dist`.
-name: "Build and publish wasm"
-
-on:
-  workflow_dispatch:
-  workflow_call:
-    inputs:
-      plan:
-        required: true
-        type: string
-
-env:
-  CARGO_INCREMENTAL: 0
-  CARGO_NET_RETRY: 10
-  CARGO_TERM_COLOR: always
-  RUSTUP_MAX_RETRIES: 10
-
-jobs:
-  ruff_wasm:
-    runs-on: ubuntu-latest
-    permissions:
-      contents: read
-      id-token: write
-    strategy:
-      matrix:
-        target: [web, bundler, nodejs]
-      fail-fast: false
-    steps:
-      - uses: actions/checkout@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-bindgen-action@v0.2.0
-      - name: "Run wasm-pack build"
-        run: wasm-pack build --target ${{ matrix.target }} crates/ruff_wasm
-      - name: "Rename generated package"
-        run: | # Replace the package name w/ jq
-          jq '.name="@astral-sh/ruff-wasm-${{ 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
-        with:
-          node-version: 20
-          registry-url: "https://registry.npmjs.org"
-      - name: "Publish (dry-run)"
-        if: ${{ inputs.plan == '' || fromJson(inputs.plan).announcement_tag_is_implicit }}
-        run: npm publish --dry-run crates/ruff_wasm/pkg
-      - name: "Publish"
-        if: ${{ inputs.plan != '' && !fromJson(inputs.plan).announcement_tag_is_implicit }}
-        run: npm publish --provenance --access public crates/ruff_wasm/pkg
-        env:
-          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}

.github/workflows/release.yml

@@ -1,12 +1,10 @@
-# This file was autogenerated by dist: https://opensource.axo.dev/cargo-dist/
-#
 # Copyright 2022-2024, axodotdev
 # SPDX-License-Identifier: MIT or Apache-2.0
 #
 # CI that:
 #
 # * checks for a Git Tag that looks like a release
-# * builds artifacts with dist (archives, installers, hashes)
+# * builds artifacts with cargo-dist (archives, installers, hashes)
 # * uploads those artifacts to temporary workflow zip
 # * on success, uploads the artifacts to a GitHub Release
 #
@@ -24,10 +22,10 @@ permissions:
 # must be a Cargo-style SemVer Version (must have at least major.minor.patch).
 #
 # If PACKAGE_NAME is specified, then the announcement will be for that
-# package (erroring out if it doesn't have the given version or isn't dist-able).
+# package (erroring out if it doesn't have the given version or isn't cargo-dist-able).
 #
 # If PACKAGE_NAME isn't specified, then the announcement will be for all
-# (dist-able) packages in the workspace with that version (this mode is
+# (cargo-dist-able) packages in the workspace with that version (this mode is
 # intended for workspaces with only one dist-able package, or with all dist-able
 # packages versioned/released in lockstep).
 #
@@ -48,7 +46,7 @@ on:
         type: string
 
 jobs:
-  # Run 'dist plan' (or host) to determine what tasks we need to do
+  # Run 'cargo dist plan' (or host) to determine what tasks we need to do
   plan:
     runs-on: "ubuntu-20.04"
     outputs:
@@ -62,16 +60,16 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
-      - name: Install dist
+      - name: Install cargo-dist
         # we specify bash to get pipefail; it guards against the `curl` command
         # failing. otherwise `sh` won't catch that `curl` returned non-0
         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
+        run: "curl --proto '=https' --tlsv1.2 -LsSf https://github.com/axodotdev/cargo-dist/releases/download/v0.18.0/cargo-dist-installer.sh | sh"
+      - name: Cache cargo-dist
         uses: actions/upload-artifact@v4
         with:
           name: cargo-dist-cache
-          path: ~/.cargo/bin/dist
+          path: ~/.cargo/bin/cargo-dist
       # sure would be cool if github gave us proper conditionals...
       # so here's a doubly-nested ternary-via-truthiness to try to provide the best possible
       # functionality based on whether this is a pull_request, and whether it's from a fork.
@@ -79,8 +77,8 @@ jobs:
       # but also really annoying to build CI around when it needs secrets to work right.)
       - id: plan
         run: |
-          dist ${{ (inputs.tag && inputs.tag != 'dry-run' && format('host --steps=create --tag={0}', inputs.tag)) || 'plan' }} --output-format=json > plan-dist-manifest.json
-          echo "dist ran successfully"
+          cargo dist ${{ (inputs.tag && inputs.tag != 'dry-run' && format('host --steps=create --tag={0}', inputs.tag)) || 'plan' }} --output-format=json > plan-dist-manifest.json
+          echo "cargo dist ran successfully"
           cat plan-dist-manifest.json
           echo "manifest=$(jq -c "." plan-dist-manifest.json)" >> "$GITHUB_OUTPUT"
       - name: "Upload dist-manifest.json"
@@ -124,12 +122,12 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
-      - name: Install cached dist
+      - name: Install cached cargo-dist
         uses: actions/download-artifact@v4
         with:
           name: cargo-dist-cache
           path: ~/.cargo/bin/
-      - run: chmod +x ~/.cargo/bin/dist
+      - run: chmod +x ~/.cargo/bin/cargo-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
@@ -140,8 +138,8 @@ jobs:
       - id: cargo-dist
         shell: bash
         run: |
-          dist build ${{ needs.plan.outputs.tag-flag }} --output-format=json "--artifacts=global" > dist-manifest.json
-          echo "dist ran successfully"
+          cargo dist build ${{ needs.plan.outputs.tag-flag }} --output-format=json "--artifacts=global" > dist-manifest.json
+          echo "cargo dist ran successfully"
 
           # Parse out what we just built and upload it to scratch storage
           echo "paths<<EOF" >> "$GITHUB_OUTPUT"
@@ -174,12 +172,12 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
-      - name: Install cached dist
+      - name: Install cached cargo-dist
         uses: actions/download-artifact@v4
         with:
           name: cargo-dist-cache
           path: ~/.cargo/bin/
-      - run: chmod +x ~/.cargo/bin/dist
+      - run: chmod +x ~/.cargo/bin/cargo-dist
       # Fetch artifacts from scratch-storage
       - name: Fetch artifacts
         uses: actions/download-artifact@v4
@@ -191,7 +189,7 @@ jobs:
       - id: host
         shell: bash
         run: |
-          dist host ${{ needs.plan.outputs.tag-flag }} --steps=upload --steps=release --output-format=json > dist-manifest.json
+          cargo dist host ${{ needs.plan.outputs.tag-flag }} --steps=upload --steps=release --output-format=json > dist-manifest.json
           echo "artifacts uploaded and released successfully"
           cat dist-manifest.json
           echo "manifest=$(jq -c "." dist-manifest.json)" >> "$GITHUB_OUTPUT"
@@ -216,32 +214,16 @@ jobs:
       "id-token": "write"
       "packages": "write"
 
-  custom-publish-wasm:
-    needs:
-      - plan
-      - host
-    if: ${{ !fromJson(needs.plan.outputs.val).announcement_is_prerelease || fromJson(needs.plan.outputs.val).publish_prereleases }}
-    uses: ./.github/workflows/publish-wasm.yml
-    with:
-      plan: ${{ needs.plan.outputs.val }}
-    secrets: inherit
-    # publish jobs get escalated permissions
-    permissions:
-      "contents": "read"
-      "id-token": "write"
-      "packages": "write"
-
   # Create a GitHub Release while uploading all files to it
   announce:
     needs:
       - plan
       - host
       - custom-publish-pypi
-      - custom-publish-wasm
     # use "always() && ..." to allow us to wait for all publish jobs while
     # 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') }}
+    if: ${{ always() && needs.host.result == 'success' && (needs.custom-publish-pypi.result == 'skipped' || needs.custom-publish-pypi.result == 'success') }}
     runs-on: "ubuntu-20.04"
     env:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/sync_typeshed.yaml

@@ -25,13 +25,11 @@ jobs:
         name: Checkout Ruff
         with:
           path: ruff
-          persist-credentials: true
       - uses: actions/checkout@v4
         name: Checkout typeshed
         with:
           repository: python/typeshed
           path: typeshed
-          persist-credentials: false
       - name: Setup git
         run: |
           git config --global user.name typeshedbot
@@ -39,13 +37,13 @@ jobs:
       - name: Sync typeshed
         id: sync
         run: |
-          rm -rf ruff/crates/red_knot_vendored/vendor/typeshed
-          mkdir ruff/crates/red_knot_vendored/vendor/typeshed
-          cp typeshed/README.md ruff/crates/red_knot_vendored/vendor/typeshed
-          cp typeshed/LICENSE ruff/crates/red_knot_vendored/vendor/typeshed
-          cp -r typeshed/stdlib ruff/crates/red_knot_vendored/vendor/typeshed/stdlib
-          rm -rf ruff/crates/red_knot_vendored/vendor/typeshed/stdlib/@tests
-          git -C typeshed rev-parse HEAD > ruff/crates/red_knot_vendored/vendor/typeshed/source_commit.txt
+          rm -rf ruff/crates/red_knot_module_resolver/vendor/typeshed
+          mkdir ruff/crates/red_knot_module_resolver/vendor/typeshed
+          cp typeshed/README.md ruff/crates/red_knot_module_resolver/vendor/typeshed
+          cp typeshed/LICENSE ruff/crates/red_knot_module_resolver/vendor/typeshed
+          cp -r typeshed/stdlib ruff/crates/red_knot_module_resolver/vendor/typeshed/stdlib
+          rm -rf ruff/crates/red_knot_module_resolver/vendor/typeshed/stdlib/@tests
+          git -C typeshed rev-parse HEAD > ruff/crates/red_knot_module_resolver/vendor/typeshed/source_commit.txt
       - name: Commit the changes
         id: commit
         if: ${{ steps.sync.outcome == 'success' }}
@@ -59,7 +57,7 @@ jobs:
         run: |
           cd ruff
           git push --force origin typeshedbot/sync-typeshed
-          gh pr list --repo "$GITHUB_REPOSITORY" --head typeshedbot/sync-typeshed --json id --jq length | grep 1 && exit 0 # exit if there is existing pr
+          gh pr list --repo $GITHUB_REPOSITORY --head typeshedbot/sync-typeshed --json id --jq length | grep 1 && exit 0 # exit if there is existing pr
           gh pr create --title "Sync vendored typeshed stubs" --body "Close and reopen this PR to trigger CI" --label "internal"
 
   create-issue-on-failure:
@@ -78,6 +76,5 @@ jobs:
               owner: "astral-sh",
               repo: "ruff",
               title: `Automated typeshed sync failed on ${new Date().toDateString()}`,
-              body: "Run listed here: https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              labels: ["bug", "red-knot"],
+              body: "Runs are listed here: https://github.com/astral-sh/ruff/actions/workflows/sync_typeshed.yaml",
             })

.github/zizmor.yml

@@ -1,12 +0,0 @@
-# Configuration for the zizmor static analysis tool, run via pre-commit in CI
-# https://woodruffw.github.io/zizmor/configuration/
-#
-# TODO: can we remove the ignores here so that our workflows are more secure?
-rules:
-  dangerous-triggers:
-    ignore:
-      - pr-comment.yaml
-  cache-poisoning:
-    ignore:
-      - build-docker.yml
-      - publish-playground.yml

.gitignore

@@ -21,14 +21,6 @@ flamegraph.svg
 # `CARGO_TARGET_DIR=target-llvm-lines RUSTFLAGS="-Csymbol-mangling-version=v0" cargo llvm-lines -p ruff --lib`
 /target*
 
-# samply profiles
-profile.json
-
-# tracing-flame traces
-tracing.folded
-tracing-flamechart.svg
-tracing-flamegraph.svg
-
 ###
 # Rust.gitignore
 ###

.markdownlint.yaml

@@ -14,18 +14,7 @@ MD041: false
 # MD013/line-length
 MD013: false
 
-# MD014/commands-show-output
-MD014: false
-
 # MD024/no-duplicate-heading
 MD024:
   # Allow when nested under different parents e.g. CHANGELOG.md
   siblings_only: true
-
-# MD046/code-block-style
-#
-# Ignore this because it conflicts with the code block style used in content
-# tabs of mkdocs-material which is to add a blank line after the content title.
-#
-# Ref: https://github.com/astral-sh/ruff/pull/15011#issuecomment-2544790854
-MD046: false

.pre-commit-config.yaml

@@ -1,14 +1,10 @@
-fail_fast: false
+fail_fast: true
 
 exclude: |
   (?x)^(
-    .github/workflows/release.yml|
-    crates/red_knot_vendored/vendor/.*|
-    crates/red_knot_project/resources/.*|
+    crates/red_knot_module_resolver/vendor/.*|
     crates/ruff_linter/resources/.*|
     crates/ruff_linter/src/rules/.*/snapshots/.*|
-    crates/ruff_notebook/resources/.*|
-    crates/ruff_server/resources/.*|
     crates/ruff/resources/.*|
     crates/ruff_python_formatter/resources/.*|
     crates/ruff_python_formatter/tests/snapshots/.*|
@@ -18,17 +14,17 @@ exclude: |
 
 repos:
   - repo: https://github.com/abravalheri/validate-pyproject
-    rev: v0.23
+    rev: v0.18
     hooks:
       - id: validate-pyproject
 
   - repo: https://github.com/executablebooks/mdformat
-    rev: 0.7.21
+    rev: 0.7.17
     hooks:
       - id: mdformat
         additional_dependencies:
-          - mdformat-mkdocs==4.0.0
-          - mdformat-footnote==0.1.1
+          - mdformat-mkdocs
+          - mdformat-admon
         exclude: |
           (?x)^(
             docs/formatter/black\.md
@@ -36,7 +32,7 @@ repos:
           )$
 
   - repo: https://github.com/igorshubovych/markdownlint-cli
-    rev: v0.43.0
+    rev: v0.41.0
     hooks:
       - id: markdownlint-fix
         exclude: |
@@ -45,21 +41,8 @@ repos:
             | docs/\w+\.md
           )$
 
-  - repo: https://github.com/adamchainz/blacken-docs
-    rev: 1.19.1
-    hooks:
-      - id: blacken-docs
-        args: ["--pyi", "--line-length", "130"]
-        files: '^crates/.*/resources/mdtest/.*\.md'
-        exclude: |
-          (?x)^(
-            .*?invalid(_.+)*_syntax\.md
-          )$
-        additional_dependencies:
-          - black==24.10.0
-
   - repo: https://github.com/crate-ci/typos
-    rev: v1.29.4
+    rev: v1.23.1
     hooks:
       - id: typos
 
@@ -73,52 +56,25 @@ repos:
         pass_filenames: false # This makes it a lot faster
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.9.2
+    rev: v0.5.1
     hooks:
       - id: ruff-format
       - id: ruff
         args: [--fix, --exit-non-zero-on-fix]
         types_or: [python, pyi]
         require_serial: true
+        exclude: |
+          (?x)^(
+            crates/ruff_linter/resources/.*|
+            crates/ruff_python_formatter/resources/.*
+          )$
 
   # Prettier
-  - repo: https://github.com/rbubley/mirrors-prettier
-    rev: v3.4.2
+  - repo: https://github.com/pre-commit/mirrors-prettier
+    rev: v3.1.0
     hooks:
       - id: prettier
         types: [yaml]
 
-  # 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: v1.1.1
-    hooks:
-      - id: zizmor
-
-  - repo: https://github.com/python-jsonschema/check-jsonschema
-    rev: 0.31.0
-    hooks:
-      - id: check-github-workflows
-
-  # `actionlint` hook, for verifying correct syntax in GitHub Actions workflows.
-  # Some additional configuration for `actionlint` can be found in `.github/actionlint.yaml`.
-  - repo: https://github.com/rhysd/actionlint
-    rev: v1.7.7
-    hooks:
-      - id: actionlint
-        stages:
-          # This hook is disabled by default, since it's quite slow.
-          # To run all hooks *including* this hook, use `uvx pre-commit run -a --hook-stage=manual`.
-          # To run *just* this hook, use `uvx pre-commit run -a actionlint --hook-stage=manual`.
-          - manual
-        args:
-          - "-ignore=SC2129" # ignorable stylistic lint from shellcheck
-          - "-ignore=SC2016" # another shellcheck lint: seems to have false positives?
-        additional_dependencies:
-          # actionlint has a shellcheck integration which extracts shell scripts in `run:` steps from GitHub Actions
-          # and checks these with shellcheck. This is arguably its most useful feature,
-          # but the integration only works if shellcheck is installed
-          - "github.com/wasilibs/go-shellcheck/cmd/shellcheck@v0.10.0"
-
 ci:
   skip: [cargo-fmt, dev-generate-all]

BREAKING_CHANGES.md

@@ -1,85 +1,5 @@
 # Breaking Changes
 
-## 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.
-
-## 0.8.0
-
-- **Default to Python 3.9**
-
-    Ruff now defaults to Python 3.9 instead of 3.8 if no explicit Python version is configured using [`ruff.target-version`](https://docs.astral.sh/ruff/settings/#target-version) or [`project.requires-python`](https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#python-requires) ([#13896](https://github.com/astral-sh/ruff/pull/13896))
-
-- **Changed location of `pydoclint` diagnostics**
-
-    [`pydoclint`](https://docs.astral.sh/ruff/rules/#pydoclint-doc) diagnostics now point to the first-line of the problematic docstring. Previously, this was not the case.
-
-    If you've opted into these preview rules but have them suppressed using
-    [`noqa`](https://docs.astral.sh/ruff/linter/#error-suppression) comments in
-    some places, this change may mean that you need to move the `noqa` suppression
-    comments. Most users should be unaffected by this change.
-
-- **Use XDG (i.e. `~/.local/bin`) instead of the Cargo home directory in the standalone installer**
-
-    Previously, Ruff's installer used `$CARGO_HOME` or `~/.cargo/bin` for its target install directory. Now, Ruff will be installed into `$XDG_BIN_HOME`, `$XDG_DATA_HOME/../bin`, or `~/.local/bin` (in that order).
-
-    This change is only relevant to users of the standalone Ruff installer (using the shell or PowerShell script). If you installed Ruff using uv or pip, you should be unaffected.
-
-- **Changes to the line width calculation**
-
-    Ruff now uses a new version of the [unicode-width](https://github.com/unicode-rs/unicode-width) Rust crate to calculate the line width. In very rare cases, this may lead to lines containing Unicode characters being reformatted, or being considered too long when they were not before ([`E501`](https://docs.astral.sh/ruff/rules/line-too-long/)).
-
-## 0.7.0
-
-- The pytest rules `PT001` and `PT023` now default to omitting the decorator parentheses when there are no arguments
-    ([#12838](https://github.com/astral-sh/ruff/pull/12838), [#13292](https://github.com/astral-sh/ruff/pull/13292)).
-    This was a change that we attempted to make in Ruff v0.6.0, but only partially made due to an error on our part.
-    See the [blog post](https://astral.sh/blog/ruff-v0.7.0) for more details.
-- The `useless-try-except` rule (in our `tryceratops` category) has been recoded from `TRY302` to
-    `TRY203` ([#13502](https://github.com/astral-sh/ruff/pull/13502)). This ensures Ruff's code is consistent with
-    the same rule in the [`tryceratops`](https://github.com/guilatrova/tryceratops) linter.
-- The `lint.allow-unused-imports` setting has been removed ([#13677](https://github.com/astral-sh/ruff/pull/13677)). Use
-    [`lint.pyflakes.allow-unused-imports`](https://docs.astral.sh/ruff/settings/#lint_pyflakes_allowed-unused-imports)
-    instead.
-
-## 0.6.0
-
-- Detect imports in `src` layouts by default for `isort` rules ([#12848](https://github.com/astral-sh/ruff/pull/12848))
-
-- The pytest rules `PT001` and `PT023` now default to omitting the decorator parentheses when there are no arguments ([#12838](https://github.com/astral-sh/ruff/pull/12838)).
-
-- Lint and format Jupyter Notebook by default ([#12878](https://github.com/astral-sh/ruff/pull/12878)).
-
-    You can disable specific rules for notebooks using [`per-file-ignores`](https://docs.astral.sh/ruff/settings/#lint_per-file-ignores):
-
-    ```toml
-    [tool.ruff.lint.per-file-ignores]
-    "*.ipynb" = ["E501"] # disable line-too-long in notebooks
-    ```
-
-    If you'd prefer to either only lint or only format Jupyter Notebook files, you can use the
-    section-specific `exclude` option to do so. For example, the following would only lint Jupyter
-    Notebook files and not format them:
-
-    ```toml
-    [tool.ruff.format]
-    exclude = ["*.ipynb"]
-    ```
-
-    And, conversely, the following would only format Jupyter Notebook files and not lint them:
-
-    ```toml
-    [tool.ruff.lint]
-    exclude = ["*.ipynb"]
-    ```
-
-    You can completely disable Jupyter Notebook support by updating the [`extend-exclude`](https://docs.astral.sh/ruff/settings/#extend-exclude) setting:
-
-    ```toml
-    [tool.ruff]
-    extend-exclude = ["*.ipynb"]
-    ```
-
 ## 0.5.0
 
 - Follow the XDG specification to discover user-level configurations on macOS (same as on other Unix platforms)
@@ -196,7 +116,7 @@ flag or `unsafe-fixes` configuration option can be used to enable unsafe fixes.
 
 See the [docs](https://docs.astral.sh/ruff/configuration/#fix-safety) for details.
 
-### Remove formatter-conflicting rules from the default rule set ([#7900](https://github.com/astral-sh/ruff/pull/7900))
+### Remove formatter-conflicting rules from the default rule set  ([#7900](https://github.com/astral-sh/ruff/pull/7900))
 
 Previously, Ruff enabled all implemented rules in Pycodestyle (`E`) by default. Ruff now only includes the
 Pycodestyle prefixes `E4`, `E7`, and `E9` to exclude rules that conflict with automatic formatters. Consequently,

CONTRIBUTING.md

@@ -2,6 +2,35 @@
 
 Welcome! We're happy to have you here. Thank you in advance for your contribution to Ruff.
 
+- [The Basics](#the-basics)
+    - [Prerequisites](#prerequisites)
+    - [Development](#development)
+    - [Project Structure](#project-structure)
+    - [Example: Adding a new lint rule](#example-adding-a-new-lint-rule)
+        - [Rule naming convention](#rule-naming-convention)
+        - [Rule testing: fixtures and snapshots](#rule-testing-fixtures-and-snapshots)
+    - [Example: Adding a new configuration option](#example-adding-a-new-configuration-option)
+- [MkDocs](#mkdocs)
+- [Release Process](#release-process)
+    - [Creating a new release](#creating-a-new-release)
+- [Ecosystem CI](#ecosystem-ci)
+- [Benchmarking and Profiling](#benchmarking-and-profiling)
+    - [CPython Benchmark](#cpython-benchmark)
+    - [Microbenchmarks](#microbenchmarks)
+        - [Benchmark-driven Development](#benchmark-driven-development)
+        - [PR Summary](#pr-summary)
+        - [Tips](#tips)
+    - [Profiling Projects](#profiling-projects)
+        - [Linux](#linux)
+        - [Mac](#mac)
+- [`cargo dev`](#cargo-dev)
+- [Subsystems](#subsystems)
+    - [Compilation Pipeline](#compilation-pipeline)
+    - [Import Categorization](#import-categorization)
+        - [Project root](#project-root)
+        - [Package root](#package-root)
+        - [Import categorization](#import-categorization-1)
+
 ## The Basics
 
 Ruff welcomes contributions in the form of pull requests.
@@ -29,14 +58,16 @@ You'll also need [Insta](https://insta.rs/docs/) to update snapshot tests:
 cargo install cargo-insta
 ```
 
-You'll need [uv](https://docs.astral.sh/uv/getting-started/installation/) (or `pipx` and `pip`) to
-run Python utility commands.
+And you'll need pre-commit to run some validation checks:
+
+```shell
+pipx install pre-commit  # or `pip install pre-commit` if you have a virtualenv
+```
 
 You can optionally install pre-commit hooks to automatically run the validation checks
 when making a commit:
 
 ```shell
-uv tool install pre-commit
 pre-commit install
 ```
 
@@ -64,7 +95,7 @@ and that it passes both the lint and test validation checks:
 ```shell
 cargo clippy --workspace --all-targets --all-features -- -D warnings  # Rust linting
 RUFF_UPDATE_SCHEMA=1 cargo test  # Rust testing and updating ruff.schema.json
-uvx pre-commit run --all-files --show-diff-on-failure  # Rust and Python formatting, Markdown and Python linting, etc.
+pre-commit run --all-files --show-diff-on-failure  # Rust and Python formatting, Markdown and Python linting, etc.
 ```
 
 These checks will run on GitHub Actions when you open your pull request, but running them locally
@@ -139,7 +170,7 @@ At a high level, the steps involved in adding a new lint rule are as follows:
 1. Create a file for your rule (e.g., `crates/ruff_linter/src/rules/flake8_bugbear/rules/assert_false.rs`).
 
 1. In that file, define a violation struct (e.g., `pub struct AssertFalse`). You can grep for
-    `#[derive(ViolationMetadata)]` to see examples.
+    `#[violation]` to see examples.
 
 1. In that file, define a function that adds the violation to the diagnostic list as appropriate
     (e.g., `pub(crate) fn assert_false`) based on whatever inputs are required for the rule (e.g.,
@@ -265,20 +296,26 @@ To preview any changes to the documentation locally:
 
 1. Install the [Rust toolchain](https://www.rust-lang.org/tools/install).
 
+1. Install MkDocs and Material for MkDocs with:
+
+    ```shell
+    pip install -r docs/requirements.txt
+    ```
+
 1. Generate the MkDocs site with:
 
     ```shell
-    uv run --no-project --isolated --with-requirements docs/requirements.txt scripts/generate_mkdocs.py
+    python scripts/generate_mkdocs.py
     ```
 
 1. Run the development server with:
 
     ```shell
     # For contributors.
-    uvx --with-requirements docs/requirements.txt -- mkdocs serve -f mkdocs.public.yml
+    mkdocs serve -f mkdocs.public.yml
 
     # For members of the Astral org, which has access to MkDocs Insiders via sponsorship.
-    uvx --with-requirements docs/requirements-insiders.txt -- mkdocs serve -f mkdocs.insiders.yml
+    mkdocs serve -f mkdocs.insiders.yml
     ```
 
 The documentation should then be available locally at
@@ -296,34 +333,22 @@ even patch releases may contain [non-backwards-compatible changes](https://semve
 ### Creating a new release
 
 1. Install `uv`: `curl -LsSf https://astral.sh/uv/install.sh | sh`
-
 1. Run `./scripts/release.sh`; this command will:
-
     - Generate a temporary virtual environment with `rooster`
     - Generate a changelog entry in `CHANGELOG.md`
     - Update versions in `pyproject.toml` and `Cargo.toml`
     - Update references to versions in the `README.md` and documentation
     - Display contributors for the release
-
 1. The changelog should then be editorialized for consistency
-
     - Often labels will be missing from pull requests they will need to be manually organized into the proper section
     - Changes should be edited to be user-facing descriptions, avoiding internal details
-
 1. Highlight any breaking changes in `BREAKING_CHANGES.md`
-
 1. Run `cargo check`. This should update the lock file with new versions.
-
 1. Create a pull request with the changelog and version updates
-
 1. Merge the PR
-
 1. Run the [release workflow](https://github.com/astral-sh/ruff/actions/workflows/release.yml) with:
-
     - The new version number (without starting `v`)
-
 1. The release workflow will do the following:
-
     1. Build all the assets. If this fails (even though we tested in step 4), we haven't tagged or
         uploaded anything, you can restart after pushing a fix. If you just need to rerun the build,
         make sure you're [re-running all the failed
@@ -334,25 +359,14 @@ even patch releases may contain [non-backwards-compatible changes](https://semve
     1. Attach artifacts to draft GitHub release
     1. Trigger downstream repositories. This can fail non-catastrophically, as we can run any
         downstream jobs manually if needed.
-
 1. Verify the GitHub release:
-
     1. The Changelog should match the content of `CHANGELOG.md`
-    1. Append the contributors from the `scripts/release.sh` script
-
+    1. Append the contributors from the `bump.sh` script
 1. If needed, [update the schemastore](https://github.com/astral-sh/ruff/blob/main/scripts/update_schemastore.py).
-
     1. One can determine if an update is needed when
         `git diff old-version-tag new-version-tag -- ruff.schema.json` returns a non-empty diff.
     1. Once run successfully, you should follow the link in the output to create a PR.
-
-1. If needed, update the [`ruff-lsp`](https://github.com/astral-sh/ruff-lsp) and
-    [`ruff-vscode`](https://github.com/astral-sh/ruff-vscode) repositories and follow
-    the release instructions in those repositories. `ruff-lsp` should always be updated
-    before `ruff-vscode`.
-
-    This step is generally not required for a patch release, but should always be done
-    for a minor release.
+1. If needed, update the `ruff-lsp` and `ruff-vscode` repositories.
 
 ## Ecosystem CI
 
@@ -360,8 +374,9 @@ GitHub Actions will run your changes against a number of real-world projects fro
 report on any linter or formatter differences. You can also run those checks locally via:
 
 ```shell
-uvx --from ./python/ruff-ecosystem ruff-ecosystem check ruff "./target/debug/ruff"
-uvx --from ./python/ruff-ecosystem ruff-ecosystem format ruff "./target/debug/ruff"
+pip install -e ./python/ruff-ecosystem
+ruff-ecosystem check ruff "./target/debug/ruff"
+ruff-ecosystem format ruff "./target/debug/ruff"
 ```
 
 See the [ruff-ecosystem package](https://github.com/astral-sh/ruff/tree/main/python/ruff-ecosystem) for more details.
@@ -374,7 +389,7 @@ We have several ways of benchmarking and profiling Ruff:
 - Microbenchmarks which run the linter or the formatter on individual files. These run on pull requests.
 - Profiling the linter on either the microbenchmarks or entire projects
 
-> **Note**
+> \[!NOTE\]
 > When running benchmarks, ensure that your CPU is otherwise idle (e.g., close any background
 > applications, like web browsers). You may also want to switch your CPU to a "performance"
 > mode, if it exists, especially when benchmarking short-lived processes.
@@ -388,18 +403,12 @@ which makes it a good target for benchmarking.
 git clone --branch 3.10 https://github.com/python/cpython.git crates/ruff_linter/resources/test/cpython
 ```
 
-Install `hyperfine`:
-
-```shell
-cargo install hyperfine
-```
-
 To benchmark the release build:
 
 ```shell
 cargo build --release && hyperfine --warmup 10 \
-  "./target/release/ruff check ./crates/ruff_linter/resources/test/cpython/ --no-cache -e" \
-  "./target/release/ruff check ./crates/ruff_linter/resources/test/cpython/ -e"
+  "./target/release/ruff ./crates/ruff_linter/resources/test/cpython/ --no-cache -e" \
+  "./target/release/ruff ./crates/ruff_linter/resources/test/cpython/ -e"
 
 Benchmark 1: ./target/release/ruff ./crates/ruff_linter/resources/test/cpython/ --no-cache
   Time (mean ± σ):     293.8 ms ±   3.2 ms    [User: 2384.6 ms, System: 90.3 ms]
@@ -418,7 +427,7 @@ To benchmark against the ecosystem's existing tools:
 
 ```shell
 hyperfine --ignore-failure --warmup 5 \
-  "./target/release/ruff check ./crates/ruff_linter/resources/test/cpython/ --no-cache" \
+  "./target/release/ruff ./crates/ruff_linter/resources/test/cpython/ --no-cache" \
   "pyflakes crates/ruff_linter/resources/test/cpython" \
   "autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython" \
   "pycodestyle crates/ruff_linter/resources/test/cpython" \
@@ -464,10 +473,10 @@ To benchmark a subset of rules, e.g. `LineTooLong` and `DocLineTooLong`:
 
 ```shell
 cargo build --release && hyperfine --warmup 10 \
-  "./target/release/ruff check ./crates/ruff_linter/resources/test/cpython/ --no-cache -e --select W505,E501"
+  "./target/release/ruff ./crates/ruff_linter/resources/test/cpython/ --no-cache -e --select W505,E501"
 ```
 
-You can run `uv venv --project ./scripts/benchmarks`, activate the venv and then run `uv sync --project ./scripts/benchmarks` to create a working environment for the
+You can run `poetry install` from `./scripts/benchmarks` to create a working environment for the
 above. All reported benchmarks were computed using the versions specified by
 `./scripts/benchmarks/pyproject.toml` on Python 3.11.
 
@@ -521,8 +530,6 @@ You can run the benchmarks with
 cargo benchmark
 ```
 
-`cargo benchmark` is an alias for `cargo bench -p ruff_benchmark --bench linter --bench formatter --`
-
 #### Benchmark-driven Development
 
 Ruff uses [Criterion.rs](https://bheisler.github.io/criterion.rs/book/) for benchmarks. You can use
@@ -561,7 +568,7 @@ cargo install critcmp
 
 #### Tips
 
-- Use `cargo bench -p ruff_benchmark <filter>` to only run specific benchmarks. For example: `cargo bench -p ruff_benchmark lexer`
+- Use `cargo bench -p ruff_benchmark <filter>` to only run specific benchmarks. For example: `cargo benchmark lexer`
     to only run the lexer benchmarks.
 - Use `cargo bench -p ruff_benchmark -- --quiet` for a more cleaned up output (without statistical relevance)
 - Use `cargo bench -p ruff_benchmark -- --quick` to get faster results (more prone to noise)
@@ -863,7 +870,7 @@ each configuration file.
 
 The package root is used to determine a file's "module path". Consider, again, `baz.py`. In that
 case, `./my_project/src/foo` was identified as the package root, so the module path for `baz.py`
-would resolve to `foo.bar.baz` — as computed by taking the relative path from the package root
+would resolve to  `foo.bar.baz` — as computed by taking the relative path from the package root
 (inclusive of the root itself). The module path can be thought of as "the path you would use to
 import the module" (e.g., `import foo.bar.baz`).
 
@@ -898,11 +905,15 @@ There are three ways in which an import can be categorized as "first-party":
     package (e.g., `from foo import bar` or `import foo.bar`), they'll be classified as first-party
     automatically. This check is as simple as comparing the first segment of the current file's
     module path to the first segment of the import.
-1. **Source roots**: Ruff supports a [`src`](https://docs.astral.sh/ruff/settings/#src) setting, which
+1. **Source roots**: Ruff supports a `[src](https://docs.astral.sh/ruff/settings/#src)` setting, which
     sets the directories to scan when identifying first-party imports. The algorithm is
     straightforward: given an import, like `import foo`, iterate over the directories enumerated in
     the `src` setting and, for each directory, check for the existence of a subdirectory `foo` or a
     file `foo.py`.
 
-By default, `src` is set to the project root, along with `"src"` subdirectory in the project root.
-This ensures that Ruff supports both flat and "src" layouts out of the box.
+By default, `src` is set to the project root. In the above example, we'd want to set
+`src = ["./src"]` to ensure that we locate `./my_project/src/foo` and thus categorize `import foo`
+as first-party in `baz.py`. In practice, for this limited example, setting `src = ["./src"]` is
+unnecessary, as all imports within `./my_project/src/foo` would be categorized as first-party via
+the same-package heuristic; but if your project contains multiple packages, you'll want to set `src`
+explicitly.

Cargo.toml

@@ -4,7 +4,7 @@ resolver = "2"
 
 [workspace.package]
 edition = "2021"
-rust-version = "1.80"
+rust-version = "1.75"
 homepage = "https://docs.astral.sh/ruff"
 documentation = "https://docs.astral.sh/ruff"
 repository = "https://github.com/astral-sh/ruff"
@@ -13,12 +13,10 @@ license = "MIT"
 
 [workspace.dependencies]
 ruff = { path = "crates/ruff" }
-ruff_annotate_snippets = { path = "crates/ruff_annotate_snippets" }
 ruff_cache = { path = "crates/ruff_cache" }
-ruff_db = { path = "crates/ruff_db", default-features = false }
+ruff_db = { path = "crates/ruff_db" }
 ruff_diagnostics = { path = "crates/ruff_diagnostics" }
 ruff_formatter = { path = "crates/ruff_formatter" }
-ruff_graph = { path = "crates/ruff_graph" }
 ruff_index = { path = "crates/ruff_index" }
 ruff_linter = { path = "crates/ruff_linter" }
 ruff_macros = { path = "crates/ruff_macros" }
@@ -35,19 +33,15 @@ ruff_python_trivia = { path = "crates/ruff_python_trivia" }
 ruff_server = { path = "crates/ruff_server" }
 ruff_source_file = { path = "crates/ruff_source_file" }
 ruff_text_size = { path = "crates/ruff_text_size" }
-red_knot_vendored = { path = "crates/red_knot_vendored" }
 ruff_workspace = { path = "crates/ruff_workspace" }
 
+red_knot = { path = "crates/red_knot" }
+red_knot_module_resolver = { path = "crates/red_knot_module_resolver" }
 red_knot_python_semantic = { path = "crates/red_knot_python_semantic" }
-red_knot_server = { path = "crates/red_knot_server" }
-red_knot_test = { path = "crates/red_knot_test" }
-red_knot_project = { path = "crates/red_knot_project", default-features = false }
 
 aho-corasick = { version = "1.1.3" }
-anstream = { version = "0.6.18" }
-anstyle = { version = "1.0.10" }
+annotate-snippets = { version = "0.9.2", features = ["color"] }
 anyhow = { version = "1.0.80" }
-assert_fs = { version = "1.1.0" }
 argfile = { version = "0.2.0" }
 bincode = { version = "1.3.3" }
 bitflags = { version = "2.5.0" }
@@ -56,42 +50,35 @@ cachedir = { version = "0.3.1" }
 camino = { version = "1.1.7" }
 chrono = { version = "0.4.35", default-features = false, features = ["clock"] }
 clap = { version = "4.5.3", features = ["derive"] }
-clap_complete_command = { version = "0.6.0" }
-clearscreen = { version = "4.0.0" }
+clap_complete_command = { version = "0.5.1" }
+clearscreen = { version = "3.0.0" }
 codspeed-criterion-compat = { version = "2.6.0", default-features = false }
-colored = { version = "3.0.0" }
+colored = { version = "2.1.0" }
 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 = "0.7.1"
 criterion = { version = "0.5.1", default-features = false }
 crossbeam = { version = "0.8.4" }
 dashmap = { version = "6.0.1" }
-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" }
-fern = { version = "0.7.0" }
+fern = { version = "0.6.1" }
 filetime = { version = "0.2.23" }
 glob = { version = "0.3.1" }
 globset = { version = "0.4.14" }
-globwalk = { version = "0.9.1" }
-hashbrown = { version = "0.15.0", default-features = false, features = [
-    "raw-entry",
-    "inline-more",
-] }
+hashbrown = "0.14.3"
 ignore = { version = "0.4.22" }
 imara-diff = { version = "0.1.5" }
 imperative = { version = "1.0.4" }
-indexmap = { version = "2.6.0" }
 indicatif = { version = "0.17.8" }
 indoc = { version = "2.0.4" }
 insta = { version = "1.35.1" }
 insta-cmd = { version = "0.6.0" }
 is-macro = { version = "0.3.5" }
 is-wsl = { version = "0.4.0" }
-itertools = { version = "0.14.0" }
+itertools = { version = "0.13.0" }
 js-sys = { version = "0.3.69" }
 jod-thread = { version = "0.1.2" }
 libc = { version = "0.2.153" }
@@ -99,29 +86,29 @@ libcst = { version = "1.1.0", default-features = false }
 log = { version = "0.4.17" }
 lsp-server = { version = "0.7.6" }
 lsp-types = { git = "https://github.com/astral-sh/lsp-types.git", rev = "3512a9f", features = [
-    "proposed",
+  "proposed",
 ] }
 matchit = { version = "0.8.1" }
 memchr = { version = "2.7.1" }
 mimalloc = { version = "0.1.39" }
 natord = { version = "1.0.9" }
-notify = { version = "8.0.0" }
+notify = { version = "6.1.1" }
+once_cell = { version = "1.19.0" }
 ordermap = { version = "0.5.0" }
 path-absolutize = { version = "3.1.1" }
 path-slash = { version = "0.2.1" }
 pathdiff = { version = "0.2.1" }
-pep440_rs = { version = "0.7.1" }
+pep440_rs = { version = "0.6.0", features = ["serde"] }
 pretty_assertions = "1.3.0"
 proc-macro2 = { version = "1.0.79" }
-pyproject-toml = { version = "0.13.4" }
-quick-junit = { version = "0.5.0" }
+pyproject-toml = { version = "0.9.0" }
+quick-junit = { version = "0.4.0" }
 quote = { version = "1.0.23" }
 rand = { version = "0.8.5" }
 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 = "88a1d7774d78f048fbd77d40abca9ebd729fd1f0" }
+salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "a1bf3a613f451af7fc0a59411c56abc47fe8e8e1" }
 schemars = { version = "0.8.16" }
 seahash = { version = "4.1.0" }
 serde = { version = "1.0.197", features = ["derive"] }
@@ -129,57 +116,47 @@ serde-wasm-bindgen = { version = "0.6.4" }
 serde_json = { version = "1.0.113" }
 serde_test = { version = "1.0.152" }
 serde_with = { version = "3.6.0", default-features = false, features = [
-    "macros",
+  "macros",
 ] }
 shellexpand = { version = "3.0.0" }
 similar = { version = "2.4.0", features = ["inline"] }
 smallvec = { version = "1.13.2" }
-snapbox = { version = "0.6.0", features = ["diff", "term-svg", "cmd", "examples"] }
 static_assertions = "1.1.0"
 strum = { version = "0.26.0", features = ["strum_macros"] }
 strum_macros = { version = "0.26.0" }
 syn = { version = "2.0.55" }
 tempfile = { version = "3.9.0" }
 test-case = { version = "3.3.1" }
-thiserror = { version = "2.0.0" }
-tikv-jemallocator = { version = "0.6.0" }
+thiserror = { version = "1.0.58" }
+tikv-jemallocator = { version = "0.5.0" }
 toml = { version = "0.8.11" }
 tracing = { version = "0.1.40" }
-tracing-flame = { version = "0.2.0" }
 tracing-indicatif = { version = "0.3.6" }
-tracing-subscriber = { version = "0.3.18", default-features = false, features = [
-    "env-filter",
-    "fmt",
-] }
-tracing-tree = { version = "0.4.0" }
-tryfn = { version = "0.2.1" }
+tracing-subscriber = { version = "0.3.18", features = ["env-filter"] }
+tracing-tree = { version = "0.3.0" }
 typed-arena = { version = "2.0.2" }
 unic-ucd-category = { version = "0.9" }
 unicode-ident = { version = "1.0.12" }
-unicode-width = { version = "0.2.0" }
+unicode-width = { version = "0.1.11" }
 unicode_names2 = { version = "1.2.2" }
 unicode-normalization = { version = "0.1.23" }
 ureq = { version = "2.9.6" }
 url = { version = "2.5.0" }
 uuid = { version = "1.6.1", features = [
-    "v4",
-    "fast-rng",
-    "macro-diagnostics",
-    "js",
+  "v4",
+  "fast-rng",
+  "macro-diagnostics",
+  "js",
 ] }
 walkdir = { version = "2.3.2" }
 wasm-bindgen = { version = "0.2.92" }
 wasm-bindgen-test = { version = "0.3.42" }
 wild = { version = "2" }
-zip = { version = "0.6.6", default-features = false }
+zip = { version = "0.6.6", default-features = false, features = ["zstd"] }
 
 [workspace.lints.rust]
 unsafe_code = "warn"
 unreachable_pub = "warn"
-unexpected_cfgs = { level = "warn", check-cfg = [
-    "cfg(fuzzing)",
-    "cfg(codspeed)",
-] }
 
 [workspace.lints.clippy]
 pedantic = { level = "warn", priority = -2 }
@@ -195,9 +172,8 @@ missing_panics_doc = "allow"
 module_name_repetitions = "allow"
 must_use_candidate = "allow"
 similar_names = "allow"
-single_match_else = "allow"
 too_many_lines = "allow"
-# Without the hashes we run into a `rustfmt` bug in some snapshot tests, see #13250
+# To allow `#[allow(clippy::all)]` in `crates/ruff_python_parser/src/python.rs`.
 needless_raw_string_hashes = "allow"
 # Disallowed restriction lints
 print_stdout = "warn"
@@ -210,13 +186,6 @@ get_unwrap = "warn"
 rc_buffer = "warn"
 rc_mutex = "warn"
 rest_pat_in_fully_bound_structs = "warn"
-# nursery rules
-redundant_clone = "warn"
-debug_assert_with_mut_call = "warn"
-unused_peekable = "warn"
-
-# Diagnostics are not actionable: Enable once https://github.com/rust-lang/rust-clippy/issues/13774 is resolved.
-large_stack_arrays = "allow"
 
 [profile.release]
 # Note that we set these explicitly, and these values
@@ -256,12 +225,12 @@ debug = 1
 [profile.dist]
 inherits = "release"
 
-# Config for 'dist'
+# Config for 'cargo dist'
 [workspace.metadata.dist]
-# The preferred dist version to use in CI (Cargo.toml SemVer syntax)
-cargo-dist-version = "0.25.2-prerelease.3"
+# The preferred cargo-dist version to use in CI (Cargo.toml SemVer syntax)
+cargo-dist-version = "0.18.0"
 # CI backends to support
-ci = "github"
+ci = ["github"]
 # The installers to generate for each app
 installers = ["shell", "powershell"]
 # The archive format to use for windows builds (defaults .zip)
@@ -270,45 +239,43 @@ windows-archive = ".zip"
 unix-archive = ".tar.gz"
 # Target platforms to build apps for (Rust target-triple syntax)
 targets = [
-    "aarch64-apple-darwin",
-    "aarch64-pc-windows-msvc",
-    "aarch64-unknown-linux-gnu",
-    "aarch64-unknown-linux-musl",
-    "arm-unknown-linux-musleabihf",
-    "armv7-unknown-linux-gnueabihf",
-    "armv7-unknown-linux-musleabihf",
-    "i686-pc-windows-msvc",
-    "i686-unknown-linux-gnu",
-    "i686-unknown-linux-musl",
-    "powerpc64-unknown-linux-gnu",
-    "powerpc64le-unknown-linux-gnu",
-    "s390x-unknown-linux-gnu",
-    "x86_64-apple-darwin",
-    "x86_64-pc-windows-msvc",
-    "x86_64-unknown-linux-gnu",
-    "x86_64-unknown-linux-musl",
+  "aarch64-apple-darwin",
+  "aarch64-pc-windows-msvc",
+  "aarch64-unknown-linux-gnu",
+  "aarch64-unknown-linux-musl",
+  "arm-unknown-linux-musleabihf",
+  "armv7-unknown-linux-gnueabihf",
+  "armv7-unknown-linux-musleabihf",
+  "i686-pc-windows-msvc",
+  "i686-unknown-linux-gnu",
+  "i686-unknown-linux-musl",
+  "powerpc64-unknown-linux-gnu",
+  "powerpc64le-unknown-linux-gnu",
+  "s390x-unknown-linux-gnu",
+  "x86_64-apple-darwin",
+  "x86_64-pc-windows-msvc",
+  "x86_64-unknown-linux-gnu",
+  "x86_64-unknown-linux-musl",
 ]
 # Whether to auto-include files like READMEs, LICENSEs, and CHANGELOGs (default true)
 auto-includes = false
-# Whether dist should create a Github Release or use an existing draft
+# Whether cargo-dist should create a GitHub Release or use an existing draft
 create-release = true
-# Which actions to run on pull requests
+# Publish jobs to run in CI
 pr-run-mode = "skip"
 # Whether CI should trigger releases with dispatches instead of tag pushes
 dispatch-releases = true
-# Which phase dist should use to create the GitHub release
+# The stage during which the GitHub Release should be created
 github-release = "announce"
 # Whether CI should include auto-generated code to build local artifacts
 build-local-artifacts = false
 # Local artifacts jobs to run in CI
 local-artifacts-jobs = ["./build-binaries", "./build-docker"]
 # Publish jobs to run in CI
-publish-jobs = ["./publish-pypi", "./publish-wasm"]
-# Post-announce jobs to run in CI
+publish-jobs = ["./publish-pypi"]
+# Announcement jobs to run in CI
 post-announce-jobs = ["./notify-dependents", "./publish-docs", "./publish-playground"]
 # Custom permissions for GitHub Jobs
-github-custom-job-permissions = { "build-docker" = { packages = "write", contents = "read" }, "publish-wasm" = { contents = "read", id-token = "write", packages = "write" } }
+github-custom-job-permissions = { "build-docker" = { packages = "write", contents = "read" } }
 # Whether to install an updater program
 install-updater = false
-# Path that installers should place binaries in
-install-path = ["$XDG_BIN_HOME/", "$XDG_DATA_HOME/../bin", "~/.local/bin"]

Dockerfile

@@ -1,4 +1,4 @@
-FROM --platform=$BUILDPLATFORM ubuntu AS build
+FROM --platform=$BUILDPLATFORM ubuntu as build
 ENV HOME="/root"
 WORKDIR $HOME
 

LICENSE

@@ -1371,28 +1371,3 @@ are:
     OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     SOFTWARE.
   """
-
-- pydoclint, licensed as follows:
-  """
-    MIT License
-
-    Copyright (c) 2023 jsh9
-
-    Permission is hereby granted, free of charge, to any person obtaining a copy
-    of this software and associated documentation files (the "Software"), to deal
-    in the Software without restriction, including without limitation the rights
-    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-    copies of the Software, and to permit persons to whom the Software is
-    furnished to do so, subject to the following conditions:
-
-    The above copyright notice and this permission notice shall be included in all
-    copies or substantial portions of the Software.
-
-    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-    SOFTWARE.
-  """

README.md

@@ -29,14 +29,14 @@ An extremely fast Python linter and code formatter, written in Rust.
 - 🐍 Installable via `pip`
 - 🛠️ `pyproject.toml` support
 - 🤝 Python 3.13 compatibility
-- ⚖️ Drop-in parity with [Flake8](https://docs.astral.sh/ruff/faq/#how-does-ruffs-linter-compare-to-flake8), isort, and [Black](https://docs.astral.sh/ruff/faq/#how-does-ruffs-formatter-compare-to-black)
+- ⚖️ Drop-in parity with [Flake8](https://docs.astral.sh/ruff/faq/#how-does-ruff-compare-to-flake8), isort, and Black
 - 📦 Built-in caching, to avoid re-analyzing unchanged files
 - 🔧 Fix support, for automatic error correction (e.g., automatically remove unused imports)
 - 📏 Over [800 built-in rules](https://docs.astral.sh/ruff/rules/), with native re-implementations
     of popular Flake8 plugins, like flake8-bugbear
 - ⌨️ First-party [editor integrations](https://docs.astral.sh/ruff/integrations/) for
-    [VS Code](https://github.com/astral-sh/ruff-vscode) and [more](https://docs.astral.sh/ruff/editors/setup)
-- 🌎 Monorepo-friendly, with [hierarchical and cascading configuration](https://docs.astral.sh/ruff/configuration/#config-file-discovery)
+    [VS Code](https://github.com/astral-sh/ruff-vscode) and [more](https://github.com/astral-sh/ruff-lsp)
+- 🌎 Monorepo-friendly, with [hierarchical and cascading configuration](https://docs.astral.sh/ruff/configuration/#pyprojecttoml-discovery)
 
 Ruff aims to be orders of magnitude faster than alternative tools while integrating more
 functionality behind a single, common interface.
@@ -110,28 +110,15 @@ For more, see the [documentation](https://docs.astral.sh/ruff/).
 1. [Who's Using Ruff?](#whos-using-ruff)
 1. [License](#license)
 
-## Getting Started<a id="getting-started"></a>
+## Getting Started
 
 For more, see the [documentation](https://docs.astral.sh/ruff/).
 
 ### Installation
 
-Ruff is available as [`ruff`](https://pypi.org/project/ruff/) on PyPI.
-
-Invoke Ruff directly with [`uvx`](https://docs.astral.sh/uv/):
+Ruff is available as [`ruff`](https://pypi.org/project/ruff/) on PyPI:
 
 ```shell
-uvx ruff check   # Lint all files in the current directory.
-uvx ruff format  # Format all files in the current directory.
-```
-
-Or install Ruff with `uv` (recommended), `pip`, or `pipx`:
-
-```shell
-# With uv.
-uv tool install ruff@latest  # Install Ruff globally.
-uv add --dev ruff            # Or add Ruff to your project.
-
 # With pip.
 pip install ruff
 
@@ -149,8 +136,8 @@ curl -LsSf https://astral.sh/ruff/install.sh | sh
 powershell -c "irm https://astral.sh/ruff/install.ps1 | iex"
 
 # For a specific version.
-curl -LsSf https://astral.sh/ruff/0.9.2/install.sh | sh
-powershell -c "irm https://astral.sh/ruff/0.9.2/install.ps1 | iex"
+curl -LsSf https://astral.sh/ruff/0.5.1/install.sh | sh
+powershell -c "irm https://astral.sh/ruff/0.5.1/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 +170,7 @@ Ruff can also be used as a [pre-commit](https://pre-commit.com/) hook via [`ruff
 ```yaml
 - repo: https://github.com/astral-sh/ruff-pre-commit
   # Ruff version.
-  rev: v0.9.2
+  rev: v0.5.1
   hooks:
     # Run the linter.
     - id: ruff
@@ -192,10 +179,11 @@ Ruff can also be used as a [pre-commit](https://pre-commit.com/) hook via [`ruff
     - id: ruff-format
 ```
 
-Ruff can also be used as a [VS Code extension](https://github.com/astral-sh/ruff-vscode) or with [various other editors](https://docs.astral.sh/ruff/editors/setup).
+Ruff can also be used as a [VS Code extension](https://github.com/astral-sh/ruff-vscode) or
+alongside any other editor through the [Ruff LSP](https://github.com/astral-sh/ruff-lsp).
 
 Ruff can also be used as a [GitHub Action](https://github.com/features/actions) via
-[`ruff-action`](https://github.com/astral-sh/ruff-action):
+[`ruff-action`](https://github.com/chartboost/ruff-action):
 
 ```yaml
 name: Ruff
@@ -205,10 +193,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: astral-sh/ruff-action@v3
+      - uses: chartboost/ruff-action@v1
 ```
 
-### Configuration<a id="configuration"></a>
+### Configuration
 
 Ruff can be configured through a `pyproject.toml`, `ruff.toml`, or `.ruff.toml` file (see:
 [_Configuration_](https://docs.astral.sh/ruff/configuration/), or [_Settings_](https://docs.astral.sh/ruff/settings/)
@@ -251,8 +239,8 @@ exclude = [
 line-length = 88
 indent-width = 4
 
-# Assume Python 3.9
-target-version = "py39"
+# Assume Python 3.8
+target-version = "py38"
 
 [lint]
 # Enable Pyflakes (`F`) and a subset of the pycodestyle (`E`)  codes by default.
@@ -304,7 +292,7 @@ features that may change prior to stabilization.
 See `ruff help` for more on Ruff's top-level commands, or `ruff help check` and `ruff help format`
 for more on the linting and formatting commands, respectively.
 
-## Rules<a id="rules"></a>
+## Rules
 
 <!-- Begin section: Rules -->
 
@@ -380,21 +368,21 @@ quality tools, including:
 
 For a complete enumeration of the supported rules, see [_Rules_](https://docs.astral.sh/ruff/rules/).
 
-## Contributing<a id="contributing"></a>
+## Contributing
 
 Contributions are welcome and highly appreciated. To get started, check out the
 [**contributing guidelines**](https://docs.astral.sh/ruff/contributing/).
 
 You can also join us on [**Discord**](https://discord.com/invite/astral-sh).
 
-## Support<a id="support"></a>
+## Support
 
 Having trouble? Check out the existing issues on [**GitHub**](https://github.com/astral-sh/ruff/issues),
 or feel free to [**open a new one**](https://github.com/astral-sh/ruff/issues/new).
 
 You can also ask for help on [**Discord**](https://discord.com/invite/astral-sh).
 
-## Acknowledgements<a id="acknowledgements"></a>
+## Acknowledgements
 
 Ruff's linter draws on both the APIs and implementation details of many other
 tools in the Python ecosystem, especially [Flake8](https://github.com/PyCQA/flake8), [Pyflakes](https://github.com/PyCQA/pyflakes),
@@ -418,7 +406,7 @@ Ruff is the beneficiary of a large number of [contributors](https://github.com/a
 
 Ruff is released under the MIT license.
 
-## Who's Using Ruff?<a id="whos-using-ruff"></a>
+## Who's Using Ruff?
 
 Ruff is used by a number of major open-source projects and companies, including:
 
@@ -430,14 +418,12 @@ Ruff is used by a number of major open-source projects and companies, including:
 - [Babel](https://github.com/python-babel/babel)
 - Benchling ([Refac](https://github.com/benchling/refac))
 - [Bokeh](https://github.com/bokeh/bokeh)
-- CrowdCent ([NumerBlox](https://github.com/crowdcent/numerblox)) <!-- typos: ignore -->
 - [Cryptography (PyCA)](https://github.com/pyca/cryptography)
 - CERN ([Indico](https://getindico.io/))
 - [DVC](https://github.com/iterative/dvc)
 - [Dagger](https://github.com/dagger/dagger)
 - [Dagster](https://github.com/dagster-io/dagster)
 - Databricks ([MLflow](https://github.com/mlflow/mlflow))
-- [Dify](https://github.com/langgenius/dify)
 - [FastAPI](https://github.com/tiangolo/fastapi)
 - [Godot](https://github.com/godotengine/godot)
 - [Gradio](https://github.com/gradio-app/gradio)
@@ -448,7 +434,6 @@ Ruff is used by a number of major open-source projects and companies, including:
 - Hugging Face ([Transformers](https://github.com/huggingface/transformers),
     [Datasets](https://github.com/huggingface/datasets),
     [Diffusers](https://github.com/huggingface/diffusers))
-- IBM ([Qiskit](https://github.com/Qiskit/qiskit))
 - ING Bank ([popmon](https://github.com/ing-bank/popmon), [probatus](https://github.com/ing-bank/probatus))
 - [Ibis](https://github.com/ibis-project/ibis)
 - [ivy](https://github.com/unifyai/ivy)
@@ -538,7 +523,7 @@ If you're using Ruff, consider adding the Ruff badge to your project's `README.m
 <a href="https://github.com/astral-sh/ruff"><img src="https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/astral-sh/ruff/main/assets/badge/v2.json" alt="Ruff" style="max-width:100%;"></a>
 ```
 
-## License<a id="license"></a>
+## License
 
 This repository is licensed under the [MIT License](https://github.com/astral-sh/ruff/blob/main/LICENSE)
 

_typos.toml

@@ -1,10 +1,6 @@
 [files]
 # https://github.com/crate-ci/typos/issues/868
-extend-exclude = [
-    "crates/red_knot_vendored/vendor/**/*",
-    "**/resources/**/*",
-    "**/snapshots/**/*",
-]
+extend-exclude = ["crates/red_knot_module_resolver/vendor/**/*", "**/resources/**/*", "**/snapshots/**/*"]
 
 [default.extend-words]
 "arange" = "arange"  # e.g. `numpy.arange`
@@ -12,18 +8,14 @@ hel = "hel"
 whos = "whos"
 spawnve = "spawnve"
 ned = "ned"
-pn = "pn"  # `import panel as pn` is a thing
+pn = "pn"  # `import panel as pd` is a thing
 poit = "poit"
 BA = "BA" # acronym for "Bad Allowed", used in testing.
 jod = "jod" # e.g., `jod-thread`
-Numer = "Numer" # Library name 'NumerBlox' in "Who's Using Ruff?"
 
 [default]
 extend-ignore-re = [
-    # Line ignore with trailing "spellchecker:disable-line"
-    "(?Rm)^.*#\\s*spellchecker:disable-line$",
-    "LICENSEs",
+  # Line ignore with trailing "spellchecker:disable-line"
+  "(?Rm)^.*#\\s*spellchecker:disable-line$",
+  "LICENSEs",
 ]
-
-[default.extend-identifiers]
-"FrIeNdLy" = "FrIeNdLy"

clippy.toml

@@ -1,25 +1,13 @@
 doc-valid-idents = [
-    "..",
-    "CodeQL",
-    "FastAPI",
-    "IPython",
-    "LangChain",
-    "LibCST",
-    "McCabe",
-    "NumPy",
-    "SCREAMING_SNAKE_CASE",
-    "SQLAlchemy",
-    "StackOverflow",
-    "PyCharm",
-    "SNMPv1",
-    "SNMPv2",
-    "SNMPv3",
-    "PyFlakes"
-]
-
-ignore-interior-mutability = [
-    # Interned is read-only. The wrapped `Rc` never gets updated.
-    "ruff_formatter::format_element::Interned",
-    # The expression is read-only.
-    "ruff_python_ast::hashable::HashableExpr",
+  "..",
+  "CodeQL",
+  "FastAPI",
+  "IPython",
+  "LangChain",
+  "LibCST",
+  "McCabe",
+  "NumPy",
+  "SCREAMING_SNAKE_CASE",
+  "SQLAlchemy",
+  "StackOverflow",
 ]

crates/red_knot/Cargo.toml

@@ -12,34 +12,24 @@ license.workspace = true
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+red_knot_module_resolver = { workspace = true }
 red_knot_python_semantic = { workspace = true }
-red_knot_project = { workspace = true, features = ["zstd"] }
-red_knot_server = { workspace = true }
-ruff_db = { workspace = true, features = ["os", "cache"] }
+
+ruff_db = { workspace = true }
+ruff_python_ast = { workspace = true }
 
 anyhow = { workspace = true }
-chrono = { workspace = true }
-clap = { workspace = true, features = ["wrap_help"] }
-colored = { workspace = true }
 countme = { workspace = true, features = ["enable"] }
 crossbeam = { workspace = true }
 ctrlc = { version = "3.4.4" }
+notify = { workspace = true }
 rayon = { workspace = true }
+rustc-hash = { workspace = true }
 salsa = { workspace = true }
-tracing = { workspace = true, features = ["release_max_level_debug"] }
-tracing-subscriber = { workspace = true, features = ["env-filter", "fmt"] }
-tracing-flame = { workspace = true }
+tracing = { workspace = true }
+tracing-subscriber = { workspace = true }
 tracing-tree = { workspace = true }
 
-[dev-dependencies]
-ruff_db = { workspace = true, features = ["testing"] }
-
-insta = { workspace = true, features = ["filters"] }
-insta-cmd = { workspace = true }
-filetime = { workspace = true }
-regex = { workspace = true }
-tempfile = { workspace = true }
-toml = { workspace = true }
 
 [lints]
 workspace = true

crates/red_knot/docs/tracing.md

@@ -1,128 +0,0 @@
-# Tracing
-
-Traces are a useful tool to narrow down the location of a bug or, at least, to understand why the compiler is doing a particular thing.
-Note, tracing messages with severity `debug` or greater are user-facing. They should be phrased accordingly.
-Tracing spans are only shown when using `-vvv`.
-
-## Verbosity levels
-
-The CLI supports different verbosity levels.
-
-- default: Only show errors and warnings.
-- `-v` activates `info!`: Show generally useful information such as paths of configuration files, detected platform, etc., but it's not a lot of messages, it's something you'll activate in CI by default. cargo build e.g. shows you which packages are fresh.
-- `-vv` activates `debug!` and timestamps: This should be enough information to get to the bottom of bug reports. When you're processing many packages or files, you'll get pages and pages of output, but each line is link to a specific action or state change.
-- `-vvv` activates `trace!` (only in debug builds) and shows tracing-spans: At this level, you're logging everything. Most of this is wasted, it's really slow, we dump e.g. the entire resolution graph. Only useful to developers, and you almost certainly want to use `RED_KNOT_LOG` to filter it down to the area your investigating.
-
-## Better logging with `RED_KNOT_LOG` and `RAYON_NUM_THREADS`
-
-By default, the CLI shows messages from the `ruff` and `red_knot` crates. Tracing messages from other crates are not shown.
-The `RED_KNOT_LOG` environment variable allows you to customize which messages are shown by specifying one
-or more [filter directives](https://docs.rs/tracing-subscriber/latest/tracing_subscriber/filter/struct.EnvFilter.html#directives).
-
-The `RAYON_NUM_THREADS` environment variable, meanwhile, can be used to control the level of concurrency red-knot uses.
-By default, red-knot will attempt to parallelize its work so that multiple files are checked simultaneously,
-but this can result in a confused logging output where messages from different threads are intertwined.
-To switch off concurrency entirely and have more readable logs, use `RAYON_NUM_THREADS=1`.
-
-### Examples
-
-#### Show all debug messages
-
-Shows debug messages from all crates.
-
-```bash
-RED_KNOT_LOG=debug
-```
-
-#### Show salsa query execution messages
-
-Show the salsa `execute: my_query` messages in addition to all red knot messages.
-
-```bash
-RED_KNOT_LOG=ruff=trace,red_knot=trace,salsa=info
-```
-
-#### Show typing traces
-
-Only show traces for the `red_knot_python_semantic::types` module.
-
-```bash
-RED_KNOT_LOG="red_knot_python_semantic::types"
-```
-
-Note: Ensure that you use `-vvv` to see tracing spans.
-
-#### Show messages for a single file
-
-Shows all messages that are inside of a span for a specific file.
-
-```bash
-RED_KNOT_LOG=red_knot[{file=/home/micha/astral/test/x.py}]=trace
-```
-
-**Note**: Tracing still shows all spans because tracing can't know at the time of entering the span
-whether one if its children has the file `x.py`.
-
-**Note**: Salsa currently logs the entire memoized values. In our case, the source text and parsed AST.
-This very quickly leads to extremely long outputs.
-
-## Tracing and Salsa
-
-Be mindful about using `tracing` in Salsa queries, especially when using `warn` or `error` because it isn't guaranteed
-that the query will execute after restoring from a persistent cache. In which case the user won't see the message.
-
-For example, don't use `tracing` to show the user a message when generating a lint violation failed
-because the message would only be shown when linting the file the first time, but not on subsequent analysis
-runs or when restoring from a persistent cache. This can be confusing for users because they
-don't understand why a specific lint violation isn't raised. Instead, change your
-query to return the failure as part of the query's result or use a Salsa accumulator.
-
-## Tracing in tests
-
-You can use `ruff_db::testing::setup_logging` or `ruff_db::testing::setup_logging_with_filter` to set up logging in tests.
-
-```rust
-use ruff_db::testing::setup_logging;
-
-#[test]
-fn test() {
-  let _logging = setup_logging();
-
-  tracing::info!("This message will be printed to stderr");
-}
-```
-
-Note: Most test runners capture stderr and only show its output when a test fails.
-
-Note also that `setup_logging` only sets up logging for the current thread because [`set_global_default`](https://docs.rs/tracing/latest/tracing/subscriber/fn.set_global_default.html) can only be
-called **once**.
-
-## Release builds
-
-`trace!` events are removed in release builds.
-
-## Profiling
-
-Red Knot generates a folded stack trace to the current directory named `tracing.folded` when setting the environment variable `RED_KNOT_LOG_PROFILE` to `1` or `true`.
-
-```bash
-RED_KNOT_LOG_PROFILE=1 red_knot -- --current-directory=../test -vvv
-```
-
-You can convert the textual representation into a visual one using `inferno`.
-
-```shell
-cargo install inferno
-```
-
-```shell
-# flamegraph
-cat tracing.folded | inferno-flamegraph > tracing-flamegraph.svg
-
-# flamechart
-cat tracing.folded | inferno-flamegraph --flamechart > tracing-flamechart.svg
-```
-
-![Example flamegraph](./tracing-flamegraph.png)
-
-See [`tracing-flame`](https://crates.io/crates/tracing-flame) for more details.

crates/red_knot/src/db.rs

@@ -0,0 +1,10 @@
+use red_knot_python_semantic::Db as SemanticDb;
+use ruff_db::Upcast;
+use salsa::DbWithJar;
+
+use crate::lint::{lint_semantic, lint_syntax, unwind_if_cancelled};
+
+pub trait Db: DbWithJar<Jar> + SemanticDb + Upcast<dyn SemanticDb> {}
+
+#[salsa::jar(db=Db)]
+pub struct Jar(lint_syntax, lint_semantic, unwind_if_cancelled);

crates/red_knot/src/lib.rs

@@ -0,0 +1,52 @@
+use rustc_hash::FxHashSet;
+
+use ruff_db::file_system::{FileSystemPath, FileSystemPathBuf};
+use ruff_db::vfs::VfsFile;
+
+use crate::db::Jar;
+
+pub mod db;
+pub mod lint;
+pub mod program;
+pub mod watch;
+
+#[derive(Debug, Clone)]
+pub struct Workspace {
+    root: FileSystemPathBuf,
+    /// The files that are open in the workspace.
+    ///
+    /// * Editor: The files that are actively being edited in the editor (the user has a tab open with the file).
+    /// * CLI: The resolved files passed as arguments to the CLI.
+    open_files: FxHashSet<VfsFile>,
+}
+
+impl Workspace {
+    pub fn new(root: FileSystemPathBuf) -> Self {
+        Self {
+            root,
+            open_files: FxHashSet::default(),
+        }
+    }
+
+    pub fn root(&self) -> &FileSystemPath {
+        self.root.as_path()
+    }
+
+    // TODO having the content in workspace feels wrong.
+    pub fn open_file(&mut self, file_id: VfsFile) {
+        self.open_files.insert(file_id);
+    }
+
+    pub fn close_file(&mut self, file_id: VfsFile) {
+        self.open_files.remove(&file_id);
+    }
+
+    // TODO introduce an `OpenFile` type instead of using an anonymous tuple.
+    pub fn open_files(&self) -> impl Iterator<Item = VfsFile> + '_ {
+        self.open_files.iter().copied()
+    }
+
+    pub fn is_file_open(&self, file_id: VfsFile) -> bool {
+        self.open_files.contains(&file_id)
+    }
+}

crates/red_knot/src/lint.rs

@@ -0,0 +1,275 @@
+use std::cell::RefCell;
+use std::ops::Deref;
+use std::time::Duration;
+
+use tracing::trace_span;
+
+use red_knot_module_resolver::ModuleName;
+use red_knot_python_semantic::types::Type;
+use red_knot_python_semantic::{HasTy, SemanticModel};
+use ruff_db::parsed::{parsed_module, ParsedModule};
+use ruff_db::source::{source_text, SourceText};
+use ruff_db::vfs::VfsFile;
+use ruff_python_ast as ast;
+use ruff_python_ast::visitor::{walk_stmt, Visitor};
+
+use crate::db::Db;
+
+/// Workaround query to test for if the computation should be cancelled.
+/// Ideally, push for Salsa to expose an API for testing if cancellation was requested.
+#[salsa::tracked]
+#[allow(unused_variables)]
+pub(crate) fn unwind_if_cancelled(db: &dyn Db) {}
+
+#[salsa::tracked(return_ref)]
+pub(crate) fn lint_syntax(db: &dyn Db, file_id: VfsFile) -> Diagnostics {
+    #[allow(clippy::print_stdout)]
+    if std::env::var("RED_KNOT_SLOW_LINT").is_ok() {
+        for i in 0..10 {
+            unwind_if_cancelled(db);
+
+            println!("RED_KNOT_SLOW_LINT is set, sleeping for {i}/10 seconds");
+            std::thread::sleep(Duration::from_secs(1));
+        }
+    }
+
+    let mut diagnostics = Vec::new();
+
+    let source = source_text(db.upcast(), file_id);
+    lint_lines(&source, &mut diagnostics);
+
+    let parsed = parsed_module(db.upcast(), file_id);
+
+    if parsed.errors().is_empty() {
+        let ast = parsed.syntax();
+
+        let mut visitor = SyntaxLintVisitor {
+            diagnostics,
+            source: &source,
+        };
+        visitor.visit_body(&ast.body);
+        diagnostics = visitor.diagnostics;
+    } else {
+        diagnostics.extend(parsed.errors().iter().map(ToString::to_string));
+    }
+
+    Diagnostics::from(diagnostics)
+}
+
+fn lint_lines(source: &str, diagnostics: &mut Vec<String>) {
+    for (line_number, line) in source.lines().enumerate() {
+        if line.len() < 88 {
+            continue;
+        }
+
+        let char_count = line.chars().count();
+        if char_count > 88 {
+            diagnostics.push(format!(
+                "Line {} is too long ({} characters)",
+                line_number + 1,
+                char_count
+            ));
+        }
+    }
+}
+
+#[salsa::tracked(return_ref)]
+pub(crate) fn lint_semantic(db: &dyn Db, file_id: VfsFile) -> Diagnostics {
+    let _span = trace_span!("lint_semantic", ?file_id).entered();
+
+    let source = source_text(db.upcast(), file_id);
+    let parsed = parsed_module(db.upcast(), file_id);
+    let semantic = SemanticModel::new(db.upcast(), file_id);
+
+    if !parsed.is_valid() {
+        return Diagnostics::Empty;
+    }
+
+    let context = SemanticLintContext {
+        source,
+        parsed,
+        semantic,
+        diagnostics: RefCell::new(Vec::new()),
+    };
+
+    SemanticVisitor { context: &context }.visit_body(parsed.suite());
+
+    Diagnostics::from(context.diagnostics.take())
+}
+
+fn lint_unresolved_imports(context: &SemanticLintContext, import: AnyImportRef) {
+    match import {
+        AnyImportRef::Import(import) => {
+            for alias in &import.names {
+                let ty = alias.ty(&context.semantic);
+
+                if ty.is_unknown() {
+                    context.push_diagnostic(format!("Unresolved import '{}'", &alias.name));
+                }
+            }
+        }
+        AnyImportRef::ImportFrom(import) => {
+            for alias in &import.names {
+                let ty = alias.ty(&context.semantic);
+
+                if ty.is_unknown() {
+                    context.push_diagnostic(format!("Unresolved import '{}'", &alias.name));
+                }
+            }
+        }
+    }
+}
+
+fn lint_bad_override(context: &SemanticLintContext, class: &ast::StmtClassDef) {
+    let semantic = &context.semantic;
+
+    // TODO we should have a special marker on the real typing module (from typeshed) so if you
+    //   have your own "typing" module in your project, we don't consider it THE typing module (and
+    //   same for other stdlib modules that our lint rules care about)
+    let Some(typing) = semantic.resolve_module(ModuleName::new("typing").unwrap()) else {
+        return;
+    };
+
+    let Some(typing_override) = semantic.public_symbol(&typing, "override") else {
+        return;
+    };
+
+    let override_ty = semantic.public_symbol_ty(typing_override);
+
+    let Type::Class(class_ty) = class.ty(semantic) else {
+        return;
+    };
+
+    for function in class
+        .body
+        .iter()
+        .filter_map(|stmt| stmt.as_function_def_stmt())
+    {
+        let Type::Function(ty) = function.ty(semantic) else {
+            return;
+        };
+
+        // TODO this shouldn't make direct use of the Db; see comment on SemanticModel::db
+        let db = semantic.db();
+
+        if ty.has_decorator(db, override_ty) {
+            let method_name = ty.name(db);
+            if class_ty.inherited_class_member(db, &method_name).is_none() {
+                // TODO should have a qualname() method to support nested classes
+                context.push_diagnostic(
+                    format!(
+                        "Method {}.{} is decorated with `typing.override` but does not override any base class method",
+                        class_ty.name(db),
+                        method_name,
+                    ));
+            }
+        }
+    }
+}
+
+pub(crate) struct SemanticLintContext<'a> {
+    source: SourceText,
+    parsed: &'a ParsedModule,
+    semantic: SemanticModel<'a>,
+    diagnostics: RefCell<Vec<String>>,
+}
+
+impl<'db> SemanticLintContext<'db> {
+    #[allow(unused)]
+    pub(crate) fn source_text(&self) -> &str {
+        self.source.as_str()
+    }
+
+    #[allow(unused)]
+    pub(crate) fn ast(&self) -> &'db ast::ModModule {
+        self.parsed.syntax()
+    }
+
+    pub(crate) fn push_diagnostic(&self, diagnostic: String) {
+        self.diagnostics.borrow_mut().push(diagnostic);
+    }
+
+    #[allow(unused)]
+    pub(crate) fn extend_diagnostics(&mut self, diagnostics: impl IntoIterator<Item = String>) {
+        self.diagnostics.get_mut().extend(diagnostics);
+    }
+}
+
+#[derive(Debug)]
+struct SyntaxLintVisitor<'a> {
+    diagnostics: Vec<String>,
+    source: &'a str,
+}
+
+impl Visitor<'_> for SyntaxLintVisitor<'_> {
+    fn visit_string_literal(&mut self, string_literal: &'_ ast::StringLiteral) {
+        // A very naive implementation of use double quotes
+        let text = &self.source[string_literal.range];
+
+        if text.starts_with('\'') {
+            self.diagnostics
+                .push("Use double quotes for strings".to_string());
+        }
+    }
+}
+
+struct SemanticVisitor<'a> {
+    context: &'a SemanticLintContext<'a>,
+}
+
+impl Visitor<'_> for SemanticVisitor<'_> {
+    fn visit_stmt(&mut self, stmt: &ast::Stmt) {
+        match stmt {
+            ast::Stmt::ClassDef(class) => {
+                lint_bad_override(self.context, class);
+            }
+            ast::Stmt::Import(import) => {
+                lint_unresolved_imports(self.context, AnyImportRef::Import(import));
+            }
+            ast::Stmt::ImportFrom(import) => {
+                lint_unresolved_imports(self.context, AnyImportRef::ImportFrom(import));
+            }
+            _ => {}
+        }
+
+        walk_stmt(self, stmt);
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum Diagnostics {
+    Empty,
+    List(Vec<String>),
+}
+
+impl Diagnostics {
+    pub fn as_slice(&self) -> &[String] {
+        match self {
+            Diagnostics::Empty => &[],
+            Diagnostics::List(list) => list.as_slice(),
+        }
+    }
+}
+
+impl Deref for Diagnostics {
+    type Target = [String];
+    fn deref(&self) -> &Self::Target {
+        self.as_slice()
+    }
+}
+
+impl From<Vec<String>> for Diagnostics {
+    fn from(value: Vec<String>) -> Self {
+        if value.is_empty() {
+            Diagnostics::Empty
+        } else {
+            Diagnostics::List(value)
+        }
+    }
+}
+
+#[derive(Copy, Clone, Debug)]
+enum AnyImportRef<'a> {
+    Import(&'a ast::StmtImport),
+    ImportFrom(&'a ast::StmtImportFrom),
+}

crates/red_knot/src/logging.rs

@@ -1,254 +0,0 @@
-//! Sets up logging for Red Knot
-
-use anyhow::Context;
-use colored::Colorize;
-use std::fmt;
-use std::fs::File;
-use std::io::BufWriter;
-use tracing::{Event, Subscriber};
-use tracing_subscriber::filter::LevelFilter;
-use tracing_subscriber::fmt::format::Writer;
-use tracing_subscriber::fmt::{FmtContext, FormatEvent, FormatFields};
-use tracing_subscriber::registry::LookupSpan;
-use tracing_subscriber::EnvFilter;
-
-/// Logging flags to `#[command(flatten)]` into your CLI
-#[derive(clap::Args, Debug, Clone, Default)]
-#[command(about = None, long_about = None)]
-pub(crate) struct Verbosity {
-    #[arg(
-        long,
-        short = 'v',
-        help = "Use verbose output (or `-vv` and `-vvv` for more verbose output)",
-        action = clap::ArgAction::Count,
-        global = true,
-    )]
-    verbose: u8,
-}
-
-impl Verbosity {
-    /// Returns the verbosity level based on the number of `-v` flags.
-    ///
-    /// Returns `None` if the user did not specify any verbosity flags.
-    pub(crate) fn level(&self) -> VerbosityLevel {
-        match self.verbose {
-            0 => VerbosityLevel::Default,
-            1 => VerbosityLevel::Verbose,
-            2 => VerbosityLevel::ExtraVerbose,
-            _ => VerbosityLevel::Trace,
-        }
-    }
-}
-
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
-pub(crate) enum VerbosityLevel {
-    /// Default output level. Only shows Ruff and Red Knot events up to the [`WARN`](tracing::Level::WARN).
-    Default,
-
-    /// Enables verbose output. Emits Ruff and Red Knot events up to the [`INFO`](tracing::Level::INFO).
-    /// Corresponds to `-v`.
-    Verbose,
-
-    /// Enables a more verbose tracing format and emits Ruff and Red Knot events up to [`DEBUG`](tracing::Level::DEBUG).
-    /// Corresponds to `-vv`
-    ExtraVerbose,
-
-    /// Enables all tracing events and uses a tree-like output format. Corresponds to `-vvv`.
-    Trace,
-}
-
-impl VerbosityLevel {
-    const fn level_filter(self) -> LevelFilter {
-        match self {
-            VerbosityLevel::Default => LevelFilter::WARN,
-            VerbosityLevel::Verbose => LevelFilter::INFO,
-            VerbosityLevel::ExtraVerbose => LevelFilter::DEBUG,
-            VerbosityLevel::Trace => LevelFilter::TRACE,
-        }
-    }
-
-    pub(crate) const fn is_trace(self) -> bool {
-        matches!(self, VerbosityLevel::Trace)
-    }
-
-    pub(crate) const fn is_extra_verbose(self) -> bool {
-        matches!(self, VerbosityLevel::ExtraVerbose)
-    }
-}
-
-pub(crate) fn setup_tracing(level: VerbosityLevel) -> anyhow::Result<TracingGuard> {
-    use tracing_subscriber::prelude::*;
-
-    // The `RED_KNOT_LOG` environment variable overrides the default log level.
-    let filter = if let Ok(log_env_variable) = std::env::var("RED_KNOT_LOG") {
-        EnvFilter::builder()
-            .parse(log_env_variable)
-            .context("Failed to parse directives specified in RED_KNOT_LOG environment variable.")?
-    } else {
-        match level {
-            VerbosityLevel::Default => {
-                // Show warning traces
-                EnvFilter::default().add_directive(LevelFilter::WARN.into())
-            }
-            level => {
-                let level_filter = level.level_filter();
-
-                // Show info|debug|trace events, but allow `RED_KNOT_LOG` to override
-                let filter = EnvFilter::default().add_directive(
-                    format!("red_knot={level_filter}")
-                        .parse()
-                        .expect("Hardcoded directive to be valid"),
-                );
-
-                filter.add_directive(
-                    format!("ruff={level_filter}")
-                        .parse()
-                        .expect("Hardcoded directive to be valid"),
-                )
-            }
-        }
-    };
-
-    let (profiling_layer, guard) = setup_profile();
-
-    let registry = tracing_subscriber::registry()
-        .with(filter)
-        .with(profiling_layer);
-
-    if level.is_trace() {
-        let subscriber = registry.with(
-            tracing_tree::HierarchicalLayer::default()
-                .with_indent_lines(true)
-                .with_indent_amount(2)
-                .with_bracketed_fields(true)
-                .with_thread_ids(true)
-                .with_targets(true)
-                .with_writer(std::io::stderr)
-                .with_timer(tracing_tree::time::Uptime::default()),
-        );
-
-        subscriber.init();
-    } else {
-        let subscriber = registry.with(
-            tracing_subscriber::fmt::layer()
-                .event_format(RedKnotFormat {
-                    display_level: true,
-                    display_timestamp: level.is_extra_verbose(),
-                    show_spans: false,
-                })
-                .with_writer(std::io::stderr),
-        );
-
-        subscriber.init();
-    }
-
-    Ok(TracingGuard {
-        _flame_guard: guard,
-    })
-}
-
-#[allow(clippy::type_complexity)]
-fn setup_profile<S>() -> (
-    Option<tracing_flame::FlameLayer<S, BufWriter<File>>>,
-    Option<tracing_flame::FlushGuard<BufWriter<File>>>,
-)
-where
-    S: Subscriber + for<'span> LookupSpan<'span>,
-{
-    if let Ok("1" | "true") = std::env::var("RED_KNOT_LOG_PROFILE").as_deref() {
-        let (layer, guard) = tracing_flame::FlameLayer::with_file("tracing.folded")
-            .expect("Flame layer to be created");
-        (Some(layer), Some(guard))
-    } else {
-        (None, None)
-    }
-}
-
-pub(crate) struct TracingGuard {
-    _flame_guard: Option<tracing_flame::FlushGuard<BufWriter<File>>>,
-}
-
-struct RedKnotFormat {
-    display_timestamp: bool,
-    display_level: bool,
-    show_spans: bool,
-}
-
-/// See <https://docs.rs/tracing-subscriber/0.3.18/src/tracing_subscriber/fmt/format/mod.rs.html#1026-1156>
-impl<S, N> FormatEvent<S, N> for RedKnotFormat
-where
-    S: Subscriber + for<'a> LookupSpan<'a>,
-    N: for<'a> FormatFields<'a> + 'static,
-{
-    fn format_event(
-        &self,
-        ctx: &FmtContext<'_, S, N>,
-        mut writer: Writer<'_>,
-        event: &Event<'_>,
-    ) -> fmt::Result {
-        let meta = event.metadata();
-        let ansi = writer.has_ansi_escapes();
-
-        if self.display_timestamp {
-            let timestamp = chrono::Local::now()
-                .format("%Y-%m-%d %H:%M:%S.%f")
-                .to_string();
-            if ansi {
-                write!(writer, "{} ", timestamp.dimmed())?;
-            } else {
-                write!(
-                    writer,
-                    "{} ",
-                    chrono::Local::now().format("%Y-%m-%d %H:%M:%S.%f")
-                )?;
-            }
-        }
-
-        if self.display_level {
-            let level = meta.level();
-            // Same colors as tracing
-            if ansi {
-                let formatted_level = level.to_string();
-                match *level {
-                    tracing::Level::TRACE => {
-                        write!(writer, "{} ", formatted_level.purple().bold())?;
-                    }
-                    tracing::Level::DEBUG => write!(writer, "{} ", formatted_level.blue().bold())?,
-                    tracing::Level::INFO => write!(writer, "{} ", formatted_level.green().bold())?,
-                    tracing::Level::WARN => write!(writer, "{} ", formatted_level.yellow().bold())?,
-                    tracing::Level::ERROR => write!(writer, "{} ", level.to_string().red().bold())?,
-                }
-            } else {
-                write!(writer, "{level} ")?;
-            }
-        }
-
-        if self.show_spans {
-            let span = event.parent();
-            let mut seen = false;
-
-            let span = span
-                .and_then(|id| ctx.span(id))
-                .or_else(|| ctx.lookup_current());
-
-            let scope = span.into_iter().flat_map(|span| span.scope().from_root());
-
-            for span in scope {
-                seen = true;
-                if ansi {
-                    write!(writer, "{}:", span.metadata().name().bold())?;
-                } else {
-                    write!(writer, "{}:", span.metadata().name())?;
-                }
-            }
-
-            if seen {
-                writer.write_char(' ')?;
-            }
-        }
-
-        ctx.field_format().format_fields(writer.by_ref(), event)?;
-
-        writeln!(writer)
-    }
-}

crates/red_knot/src/main.rs

@@ -1,171 +1,77 @@
-use std::process::{ExitCode, Termination};
 use std::sync::Mutex;
 
-use anyhow::{anyhow, Context};
-use clap::Parser;
-use colored::Colorize;
 use crossbeam::channel as crossbeam_channel;
-use python_version::PythonVersion;
-use red_knot_project::metadata::options::{EnvironmentOptions, Options};
-use red_knot_project::watch;
-use red_knot_project::watch::ProjectWatcher;
-use red_knot_project::{ProjectDatabase, ProjectMetadata};
-use red_knot_server::run_server;
-use ruff_db::diagnostic::Diagnostic;
-use ruff_db::system::{OsSystem, System, SystemPath, SystemPathBuf};
-use salsa::plumbing::ZalsaDatabase;
+use salsa::ParallelDatabase;
+use tracing::subscriber::Interest;
+use tracing::{Level, Metadata};
+use tracing_subscriber::filter::LevelFilter;
+use tracing_subscriber::layer::{Context, Filter, SubscriberExt};
+use tracing_subscriber::{Layer, Registry};
+use tracing_tree::time::Uptime;
 
-use crate::logging::{setup_tracing, Verbosity};
+use red_knot::program::{FileWatcherChange, Program};
+use red_knot::watch::FileWatcher;
+use red_knot::Workspace;
+use red_knot_module_resolver::{
+    set_module_resolution_settings, RawModuleResolutionSettings, TargetVersion,
+};
+use ruff_db::file_system::{FileSystem, FileSystemPath, OsFileSystem};
+use ruff_db::vfs::system_path_to_file;
 
-mod logging;
-mod python_version;
-mod verbosity;
-
-#[derive(Debug, Parser)]
-#[command(
-    author,
-    name = "red-knot",
-    about = "An extremely fast Python type checker."
+#[allow(
+    clippy::print_stdout,
+    clippy::unnecessary_wraps,
+    clippy::print_stderr,
+    clippy::dbg_macro
 )]
-#[command(version)]
-struct Args {
-    #[command(subcommand)]
-    pub(crate) command: Option<Command>,
+pub fn main() -> anyhow::Result<()> {
+    countme::enable(true);
+    setup_tracing();
 
-    /// Run the command within the given project directory.
-    ///
-    /// All `pyproject.toml` files will be discovered by walking up the directory tree from the given project directory,
-    /// as will the project's virtual environment (`.venv`) unless the `venv-path` option is set.
-    ///
-    /// Other command-line arguments (such as relative paths) will be resolved relative to the current working directory.
-    #[arg(long, value_name = "PROJECT")]
-    project: Option<SystemPathBuf>,
+    let arguments: Vec<_> = std::env::args().collect();
 
-    /// Path to the virtual environment the project uses.
-    ///
-    /// If provided, red-knot will use the `site-packages` directory of this virtual environment
-    /// to resolve type information for the project's third-party dependencies.
-    #[arg(long, value_name = "PATH")]
-    venv_path: Option<SystemPathBuf>,
-
-    /// Custom directory to use for stdlib typeshed stubs.
-    #[arg(long, value_name = "PATH", alias = "custom-typeshed-dir")]
-    typeshed: Option<SystemPathBuf>,
-
-    /// Additional path to use as a module-resolution source (can be passed multiple times).
-    #[arg(long, value_name = "PATH")]
-    extra_search_path: Option<Vec<SystemPathBuf>>,
-
-    /// Python version to assume when resolving types.
-    #[arg(long, value_name = "VERSION", alias = "target-version")]
-    python_version: Option<PythonVersion>,
-
-    #[clap(flatten)]
-    verbosity: Verbosity,
-
-    /// Run in watch mode by re-running whenever files change.
-    #[arg(long, short = 'W')]
-    watch: bool,
-}
-
-impl Args {
-    fn to_options(&self, cli_cwd: &SystemPath) -> Options {
-        Options {
-            environment: Some(EnvironmentOptions {
-                python_version: self.python_version.map(Into::into),
-                venv_path: self
-                    .venv_path
-                    .as_ref()
-                    .map(|venv_path| SystemPath::absolute(venv_path, cli_cwd)),
-                typeshed: self
-                    .typeshed
-                    .as_ref()
-                    .map(|typeshed| SystemPath::absolute(typeshed, cli_cwd)),
-                extra_paths: self.extra_search_path.as_ref().map(|extra_search_paths| {
-                    extra_search_paths
-                        .iter()
-                        .map(|path| SystemPath::absolute(path, cli_cwd))
-                        .collect()
-                }),
-                ..EnvironmentOptions::default()
-            }),
-            ..Default::default()
-        }
-    }
-}
-
-#[derive(Debug, clap::Subcommand)]
-pub enum Command {
-    /// Start the language server
-    Server,
-}
-
-#[allow(clippy::print_stdout, clippy::unnecessary_wraps, clippy::print_stderr)]
-pub fn main() -> ExitStatus {
-    run().unwrap_or_else(|error| {
-        use std::io::Write;
-
-        // Use `writeln` instead of `eprintln` to avoid panicking when the stderr pipe is broken.
-        let mut stderr = std::io::stderr().lock();
-
-        // This communicates that this isn't a linter error but Red Knot itself hard-errored for
-        // some reason (e.g. failed to resolve the configuration)
-        writeln!(stderr, "{}", "Red Knot failed".red().bold()).ok();
-        // Currently we generally only see one error, but e.g. with io errors when resolving
-        // the configuration it is help to chain errors ("resolving configuration failed" ->
-        // "failed to read file: subdir/pyproject.toml")
-        for cause in error.chain() {
-            writeln!(stderr, "  {} {cause}", "Cause:".bold()).ok();
-        }
-
-        ExitStatus::Error
-    })
-}
-
-fn run() -> anyhow::Result<ExitStatus> {
-    let args = Args::parse_from(std::env::args());
-
-    if matches!(args.command, Some(Command::Server)) {
-        return run_server().map(|()| ExitStatus::Success);
+    if arguments.len() < 2 {
+        eprintln!("Usage: red_knot <path>");
+        return Err(anyhow::anyhow!("Invalid arguments"));
     }
 
-    let verbosity = args.verbosity.level();
-    countme::enable(verbosity.is_trace());
-    let _guard = setup_tracing(verbosity)?;
+    let fs = OsFileSystem;
+    let entry_point = FileSystemPath::new(&arguments[1]);
 
-    // The base path to which all CLI arguments are relative to.
-    let cli_base_path = {
-        let cwd = std::env::current_dir().context("Failed to get the current working directory")?;
-        SystemPathBuf::from_path_buf(cwd)
-            .map_err(|path| {
-                anyhow!(
-                    "The current working directory `{}` contains non-Unicode characters. Red Knot only supports Unicode paths.",
-                    path.display()
-                )
-            })?
-    };
+    if !fs.exists(entry_point) {
+        eprintln!("The entry point does not exist.");
+        return Err(anyhow::anyhow!("Invalid arguments"));
+    }
 
-    let cwd = args
-        .project
-        .as_ref()
-        .map(|cwd| {
-            if cwd.as_std_path().is_dir() {
-                Ok(SystemPath::absolute(cwd, &cli_base_path))
-            } else {
-                Err(anyhow!("Provided project path `{cwd}` is not a directory"))
-            }
-        })
-        .transpose()?
-        .unwrap_or_else(|| cli_base_path.clone());
+    if !fs.is_file(entry_point) {
+        eprintln!("The entry point is not a file.");
+        return Err(anyhow::anyhow!("Invalid arguments"));
+    }
 
-    let system = OsSystem::new(cwd.clone());
-    let cli_options = args.to_options(&cwd);
-    let mut workspace_metadata = ProjectMetadata::discover(system.current_directory(), &system)?;
-    workspace_metadata.apply_cli_options(cli_options.clone());
+    let entry_point = entry_point.to_path_buf();
 
-    let mut db = ProjectDatabase::new(workspace_metadata, system)?;
+    let workspace_folder = entry_point.parent().unwrap();
+    let workspace = Workspace::new(workspace_folder.to_path_buf());
 
-    let (main_loop, main_loop_cancellation_token) = MainLoop::new(cli_options);
+    let workspace_search_path = workspace.root().to_path_buf();
+
+    let mut program = Program::new(workspace, fs);
+
+    set_module_resolution_settings(
+        &mut program,
+        RawModuleResolutionSettings {
+            extra_paths: vec![],
+            workspace_root: workspace_search_path,
+            site_packages: None,
+            custom_typeshed: None,
+            target_version: TargetVersion::Py38,
+        },
+    );
+
+    let entry_id = system_path_to_file(&program, entry_point.clone()).unwrap();
+    program.workspace_mut().open_file(entry_id);
+
+    let (main_loop, main_loop_cancellation_token) = MainLoop::new();
 
     // Listen to Ctrl+C and abort the watch mode.
     let main_loop_cancellation_token = Mutex::new(Some(main_loop_cancellation_token));
@@ -177,162 +83,121 @@ fn run() -> anyhow::Result<ExitStatus> {
         }
     })?;
 
-    let exit_status = if args.watch {
-        main_loop.watch(&mut db)?
-    } else {
-        main_loop.run(&mut db)
-    };
+    let file_changes_notifier = main_loop.file_changes_notifier();
 
-    tracing::trace!("Counts for entire CLI run:\n{}", countme::get_all());
+    // Watch for file changes and re-trigger the analysis.
+    let mut file_watcher = FileWatcher::new(move |changes| {
+        file_changes_notifier.notify(changes);
+    })?;
 
-    std::mem::forget(db);
+    file_watcher.watch_folder(workspace_folder.as_std_path())?;
 
-    Ok(exit_status)
-}
+    main_loop.run(&mut program);
 
-#[derive(Copy, Clone)]
-pub enum ExitStatus {
-    /// Checking was successful and there were no errors.
-    Success = 0,
+    println!("{}", countme::get_all());
 
-    /// Checking was successful but there were errors.
-    Failure = 1,
-
-    /// Checking failed.
-    Error = 2,
-}
-
-impl Termination for ExitStatus {
-    fn report(self) -> ExitCode {
-        ExitCode::from(self as u8)
-    }
+    Ok(())
 }
 
 struct MainLoop {
-    /// Sender that can be used to send messages to the main loop.
-    sender: crossbeam_channel::Sender<MainLoopMessage>,
-
-    /// Receiver for the messages sent **to** the main loop.
-    receiver: crossbeam_channel::Receiver<MainLoopMessage>,
-
-    /// The file system watcher, if running in watch mode.
-    watcher: Option<ProjectWatcher>,
-
-    cli_options: Options,
+    orchestrator_sender: crossbeam_channel::Sender<OrchestratorMessage>,
+    main_loop_receiver: crossbeam_channel::Receiver<MainLoopMessage>,
 }
 
 impl MainLoop {
-    fn new(cli_options: Options) -> (Self, MainLoopCancellationToken) {
-        let (sender, receiver) = crossbeam_channel::bounded(10);
+    fn new() -> (Self, MainLoopCancellationToken) {
+        let (orchestrator_sender, orchestrator_receiver) = crossbeam_channel::bounded(1);
+        let (main_loop_sender, main_loop_receiver) = crossbeam_channel::bounded(1);
+
+        let mut orchestrator = Orchestrator {
+            receiver: orchestrator_receiver,
+            sender: main_loop_sender.clone(),
+            revision: 0,
+        };
+
+        std::thread::spawn(move || {
+            orchestrator.run();
+        });
 
         (
             Self {
-                sender: sender.clone(),
-                receiver,
-                watcher: None,
-                cli_options,
+                orchestrator_sender,
+                main_loop_receiver,
+            },
+            MainLoopCancellationToken {
+                sender: main_loop_sender,
             },
-            MainLoopCancellationToken { sender },
         )
     }
 
-    fn watch(mut self, db: &mut ProjectDatabase) -> anyhow::Result<ExitStatus> {
-        tracing::debug!("Starting watch mode");
-        let sender = self.sender.clone();
-        let watcher = watch::directory_watcher(move |event| {
-            sender.send(MainLoopMessage::ApplyChanges(event)).unwrap();
-        })?;
-
-        self.watcher = Some(ProjectWatcher::new(watcher, db));
-
-        self.run(db);
-
-        Ok(ExitStatus::Success)
+    fn file_changes_notifier(&self) -> FileChangesNotifier {
+        FileChangesNotifier {
+            sender: self.orchestrator_sender.clone(),
+        }
     }
 
-    fn run(mut self, db: &mut ProjectDatabase) -> ExitStatus {
-        self.sender.send(MainLoopMessage::CheckWorkspace).unwrap();
+    #[allow(clippy::print_stderr)]
+    fn run(self, program: &mut Program) {
+        self.orchestrator_sender
+            .send(OrchestratorMessage::Run)
+            .unwrap();
 
-        let result = self.main_loop(db);
+        for message in &self.main_loop_receiver {
+            tracing::trace!("Main Loop: Tick");
 
-        tracing::debug!("Exiting main loop");
-
-        result
-    }
-
-    fn main_loop(&mut self, db: &mut ProjectDatabase) -> ExitStatus {
-        // Schedule the first check.
-        tracing::debug!("Starting main loop");
-
-        let mut revision = 0u64;
-
-        while let Ok(message) = self.receiver.recv() {
             match message {
-                MainLoopMessage::CheckWorkspace => {
-                    let db = db.clone();
-                    let sender = self.sender.clone();
+                MainLoopMessage::CheckProgram { revision } => {
+                    let program = program.snapshot();
+                    let sender = self.orchestrator_sender.clone();
 
-                    // Spawn a new task that checks the project. This needs to be done in a separate thread
+                    // Spawn a new task that checks the program. This needs to be done in a separate thread
                     // to prevent blocking the main loop here.
                     rayon::spawn(move || {
-                        if let Ok(result) = db.check() {
-                            // Send the result back to the main loop for printing.
+                        if let Ok(result) = program.check() {
                             sender
-                                .send(MainLoopMessage::CheckCompleted { result, revision })
+                                .send(OrchestratorMessage::CheckProgramCompleted {
+                                    diagnostics: result,
+                                    revision,
+                                })
                                 .unwrap();
                         }
                     });
                 }
-
-                MainLoopMessage::CheckCompleted {
-                    result,
-                    revision: check_revision,
-                } => {
-                    let has_diagnostics = !result.is_empty();
-                    if check_revision == revision {
-                        #[allow(clippy::print_stdout)]
-                        for diagnostic in result {
-                            println!("{}", diagnostic.display(db));
-                        }
-                    } else {
-                        tracing::debug!(
-                            "Discarding check result for outdated revision: current: {revision}, result revision: {check_revision}"
-                        );
-                    }
-
-                    if self.watcher.is_none() {
-                        return if has_diagnostics {
-                            ExitStatus::Failure
-                        } else {
-                            ExitStatus::Success
-                        };
-                    }
-
-                    tracing::trace!("Counts after last check:\n{}", countme::get_all());
-                }
-
                 MainLoopMessage::ApplyChanges(changes) => {
-                    revision += 1;
                     // Automatically cancels any pending queries and waits for them to complete.
-                    db.apply_changes(changes, Some(&self.cli_options));
-                    if let Some(watcher) = self.watcher.as_mut() {
-                        watcher.update(db);
-                    }
-                    self.sender.send(MainLoopMessage::CheckWorkspace).unwrap();
+                    program.apply_changes(changes);
+                }
+                MainLoopMessage::CheckCompleted(diagnostics) => {
+                    eprintln!("{}", diagnostics.join("\n"));
+                    eprintln!("{}", countme::get_all());
                 }
                 MainLoopMessage::Exit => {
-                    // Cancel any pending queries and wait for them to complete.
-                    // TODO: Don't use Salsa internal APIs
-                    //  [Zulip-Thread](https://salsa.zulipchat.com/#narrow/stream/333573-salsa-3.2E0/topic/Expose.20an.20API.20to.20cancel.20other.20queries)
-                    let _ = db.zalsa_mut();
-                    return ExitStatus::Success;
+                    eprintln!("{}", countme::get_all());
+                    return;
                 }
             }
-
-            tracing::debug!("Waiting for next main loop message.");
         }
+    }
+}
 
-        ExitStatus::Success
+impl Drop for MainLoop {
+    fn drop(&mut self) {
+        self.orchestrator_sender
+            .send(OrchestratorMessage::Shutdown)
+            .unwrap();
+    }
+}
+
+#[derive(Debug, Clone)]
+struct FileChangesNotifier {
+    sender: crossbeam_channel::Sender<OrchestratorMessage>,
+}
+
+impl FileChangesNotifier {
+    fn notify(&self, changes: Vec<FileWatcherChange>) {
+        self.sender
+            .send(OrchestratorMessage::FileChanges(changes))
+            .unwrap();
     }
 }
 
@@ -347,14 +212,165 @@ impl MainLoopCancellationToken {
     }
 }
 
+struct Orchestrator {
+    /// Sends messages to the main loop.
+    sender: crossbeam_channel::Sender<MainLoopMessage>,
+    /// Receives messages from the main loop.
+    receiver: crossbeam_channel::Receiver<OrchestratorMessage>,
+    revision: usize,
+}
+
+impl Orchestrator {
+    #[allow(clippy::print_stderr)]
+    fn run(&mut self) {
+        while let Ok(message) = self.receiver.recv() {
+            match message {
+                OrchestratorMessage::Run => {
+                    self.sender
+                        .send(MainLoopMessage::CheckProgram {
+                            revision: self.revision,
+                        })
+                        .unwrap();
+                }
+
+                OrchestratorMessage::CheckProgramCompleted {
+                    diagnostics,
+                    revision,
+                } => {
+                    // Only take the diagnostics if they are for the latest revision.
+                    if self.revision == revision {
+                        self.sender
+                            .send(MainLoopMessage::CheckCompleted(diagnostics))
+                            .unwrap();
+                    } else {
+                        tracing::debug!("Discarding diagnostics for outdated revision {revision} (current: {}).", self.revision);
+                    }
+                }
+
+                OrchestratorMessage::FileChanges(changes) => {
+                    // Request cancellation, but wait until all analysis tasks have completed to
+                    // avoid stale messages in the next main loop.
+
+                    self.revision += 1;
+                    self.debounce_changes(changes);
+                }
+                OrchestratorMessage::Shutdown => {
+                    return self.shutdown();
+                }
+            }
+        }
+    }
+
+    fn debounce_changes(&self, mut changes: Vec<FileWatcherChange>) {
+        loop {
+            // Consume possibly incoming file change messages before running a new analysis, but don't wait for more than 100ms.
+            crossbeam_channel::select! {
+                recv(self.receiver) -> message => {
+                    match message {
+                        Ok(OrchestratorMessage::Shutdown) => {
+                            return self.shutdown();
+                        }
+                        Ok(OrchestratorMessage::FileChanges(file_changes)) => {
+                            changes.extend(file_changes);
+                        }
+
+                        Ok(OrchestratorMessage::CheckProgramCompleted { .. })=> {
+                            // disregard any outdated completion message.
+                        }
+                        Ok(OrchestratorMessage::Run) => unreachable!("The orchestrator is already running."),
+
+                        Err(_) => {
+                            // There are no more senders, no point in waiting for more messages
+                            return;
+                        }
+                    }
+                },
+                default(std::time::Duration::from_millis(10)) => {
+                    // No more file changes after 10 ms, send the changes and schedule a new analysis
+                    self.sender.send(MainLoopMessage::ApplyChanges(changes)).unwrap();
+                    self.sender.send(MainLoopMessage::CheckProgram { revision: self.revision}).unwrap();
+                    return;
+                }
+            }
+        }
+    }
+
+    #[allow(clippy::unused_self)]
+    fn shutdown(&self) {
+        tracing::trace!("Shutting down orchestrator.");
+    }
+}
+
 /// Message sent from the orchestrator to the main loop.
 #[derive(Debug)]
 enum MainLoopMessage {
-    CheckWorkspace,
-    CheckCompleted {
-        result: Vec<Box<dyn Diagnostic>>,
-        revision: u64,
-    },
-    ApplyChanges(Vec<watch::ChangeEvent>),
+    CheckProgram { revision: usize },
+    CheckCompleted(Vec<String>),
+    ApplyChanges(Vec<FileWatcherChange>),
     Exit,
 }
+
+#[derive(Debug)]
+enum OrchestratorMessage {
+    Run,
+    Shutdown,
+
+    CheckProgramCompleted {
+        diagnostics: Vec<String>,
+        revision: usize,
+    },
+
+    FileChanges(Vec<FileWatcherChange>),
+}
+
+fn setup_tracing() {
+    let subscriber = Registry::default().with(
+        tracing_tree::HierarchicalLayer::default()
+            .with_indent_lines(true)
+            .with_indent_amount(2)
+            .with_bracketed_fields(true)
+            .with_thread_ids(true)
+            .with_targets(true)
+            .with_writer(|| Box::new(std::io::stderr()))
+            .with_timer(Uptime::default())
+            .with_filter(LoggingFilter {
+                trace_level: Level::TRACE,
+            }),
+    );
+
+    tracing::subscriber::set_global_default(subscriber).unwrap();
+}
+
+struct LoggingFilter {
+    trace_level: Level,
+}
+
+impl LoggingFilter {
+    fn is_enabled(&self, meta: &Metadata<'_>) -> bool {
+        let filter = if meta.target().starts_with("red_knot") || meta.target().starts_with("ruff") {
+            self.trace_level
+        } else {
+            Level::INFO
+        };
+
+        meta.level() <= &filter
+    }
+}
+
+impl<S> Filter<S> for LoggingFilter {
+    fn enabled(&self, meta: &Metadata<'_>, _cx: &Context<'_, S>) -> bool {
+        self.is_enabled(meta)
+    }
+
+    fn callsite_enabled(&self, meta: &'static Metadata<'static>) -> Interest {
+        if self.is_enabled(meta) {
+            Interest::always()
+        } else {
+            Interest::never()
+        }
+    }
+
+    fn max_level_hint(&self) -> Option<LevelFilter> {
+        Some(LevelFilter::from_level(self.trace_level))
+    }
+}

crates/red_knot/src/program/check.rs

@@ -0,0 +1,32 @@
+use ruff_db::vfs::VfsFile;
+use salsa::Cancelled;
+
+use crate::lint::{lint_semantic, lint_syntax, Diagnostics};
+use crate::program::Program;
+
+impl Program {
+    /// Checks all open files in the workspace and its dependencies.
+    #[tracing::instrument(level = "debug", skip_all)]
+    pub fn check(&self) -> Result<Vec<String>, Cancelled> {
+        self.with_db(|db| {
+            let mut result = Vec::new();
+            for open_file in db.workspace.open_files() {
+                result.extend_from_slice(&db.check_file_impl(open_file));
+            }
+
+            result
+        })
+    }
+
+    #[tracing::instrument(level = "debug", skip(self))]
+    pub fn check_file(&self, file: VfsFile) -> Result<Diagnostics, Cancelled> {
+        self.with_db(|db| db.check_file_impl(file))
+    }
+
+    fn check_file_impl(&self, file: VfsFile) -> Diagnostics {
+        let mut diagnostics = Vec::new();
+        diagnostics.extend_from_slice(lint_syntax(self, file));
+        diagnostics.extend_from_slice(lint_semantic(self, file));
+        Diagnostics::from(diagnostics)
+    }
+}

crates/red_knot/src/program/mod.rs

@@ -0,0 +1,131 @@
+use std::panic::{RefUnwindSafe, UnwindSafe};
+use std::sync::Arc;
+
+use salsa::{Cancelled, Database};
+
+use red_knot_module_resolver::{Db as ResolverDb, Jar as ResolverJar};
+use red_knot_python_semantic::{Db as SemanticDb, Jar as SemanticJar};
+use ruff_db::file_system::{FileSystem, FileSystemPathBuf};
+use ruff_db::vfs::{Vfs, VfsFile, VfsPath};
+use ruff_db::{Db as SourceDb, Jar as SourceJar, Upcast};
+
+use crate::db::{Db, Jar};
+use crate::Workspace;
+
+mod check;
+
+#[salsa::db(SourceJar, ResolverJar, SemanticJar, Jar)]
+pub struct Program {
+    storage: salsa::Storage<Program>,
+    vfs: Vfs,
+    fs: Arc<dyn FileSystem + Send + Sync + RefUnwindSafe>,
+    workspace: Workspace,
+}
+
+impl Program {
+    pub fn new<Fs>(workspace: Workspace, file_system: Fs) -> Self
+    where
+        Fs: FileSystem + 'static + Send + Sync + RefUnwindSafe,
+    {
+        Self {
+            storage: salsa::Storage::default(),
+            vfs: Vfs::default(),
+            fs: Arc::new(file_system),
+            workspace,
+        }
+    }
+
+    pub fn apply_changes<I>(&mut self, changes: I)
+    where
+        I: IntoIterator<Item = FileWatcherChange>,
+    {
+        for change in changes {
+            VfsFile::touch_path(self, &VfsPath::file_system(change.path));
+        }
+    }
+
+    pub fn workspace(&self) -> &Workspace {
+        &self.workspace
+    }
+
+    pub fn workspace_mut(&mut self) -> &mut Workspace {
+        &mut self.workspace
+    }
+
+    #[allow(clippy::unnecessary_wraps)]
+    fn with_db<F, T>(&self, f: F) -> Result<T, Cancelled>
+    where
+        F: FnOnce(&Program) -> T + UnwindSafe,
+    {
+        // TODO: Catch in `Caancelled::catch`
+        //  See https://salsa.zulipchat.com/#narrow/stream/145099-general/topic/How.20to.20use.20.60Cancelled.3A.3Acatch.60
+        Ok(f(self))
+    }
+}
+
+impl Upcast<dyn SemanticDb> for Program {
+    fn upcast(&self) -> &(dyn SemanticDb + 'static) {
+        self
+    }
+}
+
+impl Upcast<dyn SourceDb> for Program {
+    fn upcast(&self) -> &(dyn SourceDb + 'static) {
+        self
+    }
+}
+
+impl Upcast<dyn ResolverDb> for Program {
+    fn upcast(&self) -> &(dyn ResolverDb + 'static) {
+        self
+    }
+}
+
+impl ResolverDb for Program {}
+
+impl SemanticDb for Program {}
+
+impl SourceDb for Program {
+    fn file_system(&self) -> &dyn FileSystem {
+        &*self.fs
+    }
+
+    fn vfs(&self) -> &Vfs {
+        &self.vfs
+    }
+}
+
+impl Database for Program {}
+
+impl Db for Program {}
+
+impl salsa::ParallelDatabase for Program {
+    fn snapshot(&self) -> salsa::Snapshot<Self> {
+        salsa::Snapshot::new(Self {
+            storage: self.storage.snapshot(),
+            vfs: self.vfs.snapshot(),
+            fs: self.fs.clone(),
+            workspace: self.workspace.clone(),
+        })
+    }
+}
+
+#[derive(Clone, Debug)]
+pub struct FileWatcherChange {
+    path: FileSystemPathBuf,
+    #[allow(unused)]
+    kind: FileChangeKind,
+}
+
+impl FileWatcherChange {
+    pub fn new(path: FileSystemPathBuf, kind: FileChangeKind) -> Self {
+        Self { path, kind }
+    }
+}
+
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum FileChangeKind {
+    Created,
+    Modified,
+    Deleted,
+}

crates/red_knot/src/python_version.rs

@@ -1,68 +0,0 @@
-/// Enumeration of all supported Python versions
-///
-/// TODO: unify with the `PythonVersion` enum in the linter/formatter crates?
-#[derive(Copy, Clone, Hash, Debug, PartialEq, Eq, PartialOrd, Ord, Default, clap::ValueEnum)]
-pub enum PythonVersion {
-    #[value(name = "3.7")]
-    Py37,
-    #[value(name = "3.8")]
-    Py38,
-    #[default]
-    #[value(name = "3.9")]
-    Py39,
-    #[value(name = "3.10")]
-    Py310,
-    #[value(name = "3.11")]
-    Py311,
-    #[value(name = "3.12")]
-    Py312,
-    #[value(name = "3.13")]
-    Py313,
-}
-
-impl PythonVersion {
-    const fn as_str(self) -> &'static str {
-        match self {
-            Self::Py37 => "3.7",
-            Self::Py38 => "3.8",
-            Self::Py39 => "3.9",
-            Self::Py310 => "3.10",
-            Self::Py311 => "3.11",
-            Self::Py312 => "3.12",
-            Self::Py313 => "3.13",
-        }
-    }
-}
-
-impl std::fmt::Display for PythonVersion {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.write_str(self.as_str())
-    }
-}
-
-impl From<PythonVersion> for red_knot_python_semantic::PythonVersion {
-    fn from(value: PythonVersion) -> Self {
-        match value {
-            PythonVersion::Py37 => Self::PY37,
-            PythonVersion::Py38 => Self::PY38,
-            PythonVersion::Py39 => Self::PY39,
-            PythonVersion::Py310 => Self::PY310,
-            PythonVersion::Py311 => Self::PY311,
-            PythonVersion::Py312 => Self::PY312,
-            PythonVersion::Py313 => Self::PY313,
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use crate::python_version::PythonVersion;
-
-    #[test]
-    fn same_default_as_python_version() {
-        assert_eq!(
-            red_knot_python_semantic::PythonVersion::from(PythonVersion::default()),
-            red_knot_python_semantic::PythonVersion::default()
-        );
-    }
-}

crates/red_knot/src/verbosity.rs

@@ -1 +0,0 @@
-

crates/red_knot/src/watch.rs

@@ -0,0 +1,82 @@
+use std::path::Path;
+
+use crate::program::{FileChangeKind, FileWatcherChange};
+use anyhow::Context;
+use notify::event::{CreateKind, RemoveKind};
+use notify::{recommended_watcher, Event, EventKind, RecommendedWatcher, RecursiveMode, Watcher};
+use ruff_db::file_system::FileSystemPath;
+
+pub struct FileWatcher {
+    watcher: RecommendedWatcher,
+}
+
+pub trait EventHandler: Send + 'static {
+    fn handle(&self, changes: Vec<FileWatcherChange>);
+}
+
+impl<F> EventHandler for F
+where
+    F: Fn(Vec<FileWatcherChange>) + Send + 'static,
+{
+    fn handle(&self, changes: Vec<FileWatcherChange>) {
+        let f = self;
+        f(changes);
+    }
+}
+
+impl FileWatcher {
+    pub fn new<E>(handler: E) -> anyhow::Result<Self>
+    where
+        E: EventHandler,
+    {
+        Self::from_handler(Box::new(handler))
+    }
+
+    fn from_handler(handler: Box<dyn EventHandler>) -> anyhow::Result<Self> {
+        let watcher = recommended_watcher(move |changes: notify::Result<Event>| {
+            match changes {
+                Ok(event) => {
+                    // TODO verify that this handles all events correctly
+                    let change_kind = match event.kind {
+                        EventKind::Create(CreateKind::File) => FileChangeKind::Created,
+                        EventKind::Modify(_) => FileChangeKind::Modified,
+                        EventKind::Remove(RemoveKind::File) => FileChangeKind::Deleted,
+                        _ => {
+                            return;
+                        }
+                    };
+
+                    let mut changes = Vec::new();
+
+                    for path in event.paths {
+                        if path.is_file() {
+                            if let Some(fs_path) = FileSystemPath::from_std_path(&path) {
+                                changes.push(FileWatcherChange::new(
+                                    fs_path.to_path_buf(),
+                                    change_kind,
+                                ));
+                            }
+                        }
+                    }
+
+                    if !changes.is_empty() {
+                        handler.handle(changes);
+                    }
+                }
+                // TODO proper error handling
+                Err(err) => {
+                    panic!("Error: {err}");
+                }
+            }
+        })
+        .context("Failed to create file watcher.")?;
+
+        Ok(Self { watcher })
+    }
+
+    pub fn watch_folder(&mut self, path: &Path) -> anyhow::Result<()> {
+        self.watcher.watch(path, RecursiveMode::Recursive)?;
+
+        Ok(())
+    }
+}

crates/red_knot/tests/cli.rs

@@ -1,60 +0,0 @@
-use anyhow::Context;
-use insta_cmd::{assert_cmd_snapshot, get_cargo_bin};
-use std::process::Command;
-use tempfile::TempDir;
-
-/// Specifying an option on the CLI should take precedence over the same setting in the
-/// project's configuration.
-#[test]
-fn test_config_override() -> anyhow::Result<()> {
-    let tempdir = TempDir::new()?;
-
-    std::fs::write(
-        tempdir.path().join("pyproject.toml"),
-        r#"
-[tool.knot.environment]
-python-version = "3.11"
-"#,
-    )
-    .context("Failed to write settings")?;
-
-    std::fs::write(
-        tempdir.path().join("test.py"),
-        r#"
-import sys
-
-# Access `sys.last_exc` that was only added in Python 3.12
-print(sys.last_exc)
-"#,
-    )
-    .context("Failed to write test.py")?;
-
-    insta::with_settings!({filters => vec![(&*tempdir_filter(&tempdir), "<temp_dir>/")]}, {
-        assert_cmd_snapshot!(knot().arg("--project").arg(tempdir.path()), @r"
-        success: false
-        exit_code: 1
-        ----- stdout -----
-        error[lint:unresolved-attribute] <temp_dir>/test.py:5:7 Type `<module 'sys'>` has no attribute `last_exc`
-
-        ----- stderr -----
-        ");
-    });
-
-    assert_cmd_snapshot!(knot().arg("--project").arg(tempdir.path()).arg("--python-version").arg("3.12"), @r"
-    success: true
-    exit_code: 0
-    ----- stdout -----
-
-    ----- stderr -----
-    ");
-
-    Ok(())
-}
-
-fn knot() -> Command {
-    Command::new(get_cargo_bin("red_knot"))
-}
-
-fn tempdir_filter(tempdir: &TempDir) -> String {
-    format!(r"{}\\?/?", regex::escape(tempdir.path().to_str().unwrap()))
-}

crates/red_knot_module_resolver/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "red_knot_vendored"
+name = "red_knot_module_resolver"
 version = "0.0.0"
 publish = false
 authors = { workspace = true }
@@ -12,20 +12,25 @@ license = { workspace = true }
 
 [dependencies]
 ruff_db = { workspace = true }
+ruff_python_stdlib = { workspace = true }
+
+compact_str = { workspace = true }
+camino = { workspace = true }
+rustc-hash = { workspace = true }
+salsa = { workspace = true }
+tracing = { workspace = true }
 zip = { workspace = true }
 
 [build-dependencies]
 path-slash = { workspace = true }
 walkdir = { workspace = true }
-zip = { workspace = true, features = ["zstd", "deflate"] }
+zip = { workspace = true }
 
 [dev-dependencies]
+anyhow = { workspace = true }
+insta = { workspace = true }
+tempfile = { workspace = true }
 walkdir = { workspace = true }
 
-[features]
-zstd = ["zip/zstd"]
-deflate = ["zip/deflate"]
-
 [lints]
 workspace = true
-

crates/red_knot_module_resolver/README.md

@@ -1,5 +1,9 @@
-# Vendored types for the stdlib
+# Red Knot
 
-This crate vendors [typeshed](https://github.com/python/typeshed)'s stubs for the standard library. The vendored stubs can be found in `crates/red_knot_vendored/vendor/typeshed`. The file `crates/red_knot_vendored/vendor/typeshed/source_commit.txt` tells you the typeshed commit that our vendored stdlib stubs currently correspond to.
+A work-in-progress multifile module resolver for Ruff.
+
+## Vendored types for the stdlib
+
+This crate vendors [typeshed](https://github.com/python/typeshed)'s stubs for the standard library. The vendored stubs can be found in `crates/red_knot_module_resolver/vendor/typeshed`. The file `crates/red_knot_module_resolver/vendor/typeshed/source_commit.txt` tells you the typeshed commit that our vendored stdlib stubs currently correspond to.
 
 The typeshed stubs are updated every two weeks via an automated PR using the `sync_typeshed.yaml` workflow in the `.github/workflows` directory. This workflow can also be triggered at any time via [workflow dispatch](https://docs.github.com/en/actions/using-workflows/manually-running-a-workflow#running-a-workflow).

crates/red_knot_module_resolver/build.rs

@@ -3,10 +3,9 @@
 //!
 //! This script should be automatically run at build time
 //! whenever the script itself changes, or whenever any files
-//! in `crates/red_knot_vendored/vendor/typeshed` change.
+//! in `crates/red_knot_module_resolver/vendor/typeshed` change.
 
 use std::fs::File;
-use std::io::Write;
 use std::path::Path;
 
 use path_slash::PathExt;
@@ -15,41 +14,24 @@ use zip::write::{FileOptions, ZipWriter};
 use zip::CompressionMethod;
 
 const TYPESHED_SOURCE_DIR: &str = "vendor/typeshed";
-const KNOT_EXTENSIONS_STUBS: &str = "knot_extensions/knot_extensions.pyi";
 const TYPESHED_ZIP_LOCATION: &str = "/zipped_typeshed.zip";
 
-/// Recursively zip the contents of the entire typeshed directory and patch typeshed
-/// on the fly to include the `knot_extensions` module.
+/// Recursively zip the contents of an entire directory.
 ///
 /// This routine is adapted from a recipe at
 /// <https://github.com/zip-rs/zip-old/blob/5d0f198124946b7be4e5969719a7f29f363118cd/examples/write_dir.rs>
-fn write_zipped_typeshed_to(writer: File) -> ZipResult<File> {
+fn zip_dir(directory_path: &str, writer: File) -> ZipResult<File> {
     let mut zip = ZipWriter::new(writer);
 
-    // Use deflated compression for WASM builds because compiling `zstd-sys` requires clang
-    // [source](https://github.com/gyscos/zstd-rs/wiki/Compile-for-WASM) which complicates the build
-    // by a lot. Deflated compression is slower but it shouldn't matter much for the WASM use case
-    // (WASM itself is already slower than a native build for a specific platform).
-    // We can't use `#[cfg(...)]` here because the target-arch in a build script is the
-    // architecture of the system running the build script and not the architecture of the build-target.
-    // That's why we use the `TARGET` environment variable here.
-    let method = if cfg!(feature = "zstd") {
-        CompressionMethod::Zstd
-    } else if cfg!(feature = "deflate") {
-        CompressionMethod::Deflated
-    } else {
-        CompressionMethod::Stored
-    };
-
     let options = FileOptions::default()
-        .compression_method(method)
+        .compression_method(CompressionMethod::Zstd)
         .unix_permissions(0o644);
 
-    for entry in walkdir::WalkDir::new(TYPESHED_SOURCE_DIR) {
+    for entry in walkdir::WalkDir::new(directory_path) {
         let dir_entry = entry.unwrap();
         let absolute_path = dir_entry.path();
         let normalized_relative_path = absolute_path
-            .strip_prefix(Path::new(TYPESHED_SOURCE_DIR))
+            .strip_prefix(Path::new(directory_path))
             .unwrap()
             .to_slash()
             .expect("Unexpected non-utf8 typeshed path!");
@@ -58,14 +40,9 @@ fn write_zipped_typeshed_to(writer: File) -> ZipResult<File> {
         // Some unzip tools unzip files with directory paths correctly, some do not!
         if absolute_path.is_file() {
             println!("adding file {absolute_path:?} as {normalized_relative_path:?} ...");
-            zip.start_file(&*normalized_relative_path, options)?;
+            zip.start_file(normalized_relative_path, options)?;
             let mut f = File::open(absolute_path)?;
             std::io::copy(&mut f, &mut zip).unwrap();
-
-            // Patch the VERSIONS file to make `knot_extensions` available
-            if normalized_relative_path == "stdlib/VERSIONS" {
-                writeln!(&mut zip, "knot_extensions: 3.0-")?;
-            }
         } else if !normalized_relative_path.is_empty() {
             // Only if not root! Avoids path spec / warning
             // and mapname conversion failed error on unzip
@@ -73,17 +50,11 @@ fn write_zipped_typeshed_to(writer: File) -> ZipResult<File> {
             zip.add_directory(normalized_relative_path, options)?;
         }
     }
-
-    // Patch typeshed and add the stubs for the `knot_extensions` module
-    println!("adding file {KNOT_EXTENSIONS_STUBS} as stdlib/knot_extensions.pyi ...");
-    zip.start_file("stdlib/knot_extensions.pyi", options)?;
-    let mut f = File::open(KNOT_EXTENSIONS_STUBS)?;
-    std::io::copy(&mut f, &mut zip).unwrap();
-
     zip.finish()
 }
 
 fn main() {
+    println!("cargo:rerun-if-changed={TYPESHED_SOURCE_DIR}");
     assert!(
         Path::new(TYPESHED_SOURCE_DIR).is_dir(),
         "Where is typeshed?"
@@ -98,6 +69,6 @@ fn main() {
     // which can't be done at compile time.)
     let zipped_typeshed_location = format!("{out_dir}{TYPESHED_ZIP_LOCATION}");
 
-    let zipped_typeshed_file = File::create(zipped_typeshed_location).unwrap();
-    write_zipped_typeshed_to(zipped_typeshed_file).unwrap();
+    let zipped_typeshed = File::create(zipped_typeshed_location).unwrap();
+    zip_dir(TYPESHED_SOURCE_DIR, zipped_typeshed).unwrap();
 }

crates/red_knot_module_resolver/src/db.rs

@@ -0,0 +1,264 @@
+use ruff_db::Upcast;
+
+use crate::resolver::{
+    file_to_module,
+    internal::{ModuleNameIngredient, ModuleResolverSettings},
+    resolve_module_query,
+};
+use crate::typeshed::parse_typeshed_versions;
+
+#[salsa::jar(db=Db)]
+pub struct Jar(
+    ModuleNameIngredient<'_>,
+    ModuleResolverSettings,
+    resolve_module_query,
+    file_to_module,
+    parse_typeshed_versions,
+);
+
+pub trait Db: salsa::DbWithJar<Jar> + ruff_db::Db + Upcast<dyn ruff_db::Db> {}
+
+#[cfg(test)]
+pub(crate) mod tests {
+    use std::sync;
+
+    use salsa::DebugWithDb;
+
+    use ruff_db::file_system::{FileSystem, FileSystemPathBuf, MemoryFileSystem, OsFileSystem};
+    use ruff_db::vfs::Vfs;
+
+    use crate::resolver::{set_module_resolution_settings, RawModuleResolutionSettings};
+    use crate::supported_py_version::TargetVersion;
+
+    use super::*;
+
+    #[salsa::db(Jar, ruff_db::Jar)]
+    pub(crate) struct TestDb {
+        storage: salsa::Storage<Self>,
+        file_system: TestFileSystem,
+        events: sync::Arc<sync::Mutex<Vec<salsa::Event>>>,
+        vfs: Vfs,
+    }
+
+    impl TestDb {
+        pub(crate) fn new() -> Self {
+            Self {
+                storage: salsa::Storage::default(),
+                file_system: TestFileSystem::Memory(MemoryFileSystem::default()),
+                events: sync::Arc::default(),
+                vfs: Vfs::with_stubbed_vendored(),
+            }
+        }
+
+        /// Returns the memory file system.
+        ///
+        /// ## Panics
+        /// If this test db isn't using a memory file system.
+        pub(crate) fn memory_file_system(&self) -> &MemoryFileSystem {
+            if let TestFileSystem::Memory(fs) = &self.file_system {
+                fs
+            } else {
+                panic!("The test db is not using a memory file system");
+            }
+        }
+
+        /// Uses the real file system instead of the memory file system.
+        ///
+        /// This useful for testing advanced file system features like permissions, symlinks, etc.
+        ///
+        /// Note that any files written to the memory file system won't be copied over.
+        pub(crate) fn with_os_file_system(&mut self) {
+            self.file_system = TestFileSystem::Os(OsFileSystem);
+        }
+
+        #[allow(unused)]
+        pub(crate) fn vfs_mut(&mut self) -> &mut Vfs {
+            &mut self.vfs
+        }
+
+        /// Takes the salsa events.
+        ///
+        /// ## Panics
+        /// If there are any pending salsa snapshots.
+        pub(crate) fn take_salsa_events(&mut self) -> Vec<salsa::Event> {
+            let inner = sync::Arc::get_mut(&mut self.events).expect("no pending salsa snapshots");
+
+            let events = inner.get_mut().unwrap();
+            std::mem::take(&mut *events)
+        }
+
+        /// Clears the salsa events.
+        ///
+        /// ## Panics
+        /// If there are any pending salsa snapshots.
+        pub(crate) fn clear_salsa_events(&mut self) {
+            self.take_salsa_events();
+        }
+    }
+
+    impl Upcast<dyn ruff_db::Db> for TestDb {
+        fn upcast(&self) -> &(dyn ruff_db::Db + 'static) {
+            self
+        }
+    }
+
+    impl ruff_db::Db for TestDb {
+        fn file_system(&self) -> &dyn ruff_db::file_system::FileSystem {
+            self.file_system.inner()
+        }
+
+        fn vfs(&self) -> &ruff_db::vfs::Vfs {
+            &self.vfs
+        }
+    }
+
+    impl Db for TestDb {}
+
+    impl salsa::Database for TestDb {
+        fn salsa_event(&self, event: salsa::Event) {
+            tracing::trace!("event: {:?}", event.debug(self));
+            let mut events = self.events.lock().unwrap();
+            events.push(event);
+        }
+    }
+
+    impl salsa::ParallelDatabase for TestDb {
+        fn snapshot(&self) -> salsa::Snapshot<Self> {
+            salsa::Snapshot::new(Self {
+                storage: self.storage.snapshot(),
+                file_system: self.file_system.snapshot(),
+                events: self.events.clone(),
+                vfs: self.vfs.snapshot(),
+            })
+        }
+    }
+
+    enum TestFileSystem {
+        Memory(MemoryFileSystem),
+        #[allow(unused)]
+        Os(OsFileSystem),
+    }
+
+    impl TestFileSystem {
+        fn inner(&self) -> &dyn FileSystem {
+            match self {
+                Self::Memory(inner) => inner,
+                Self::Os(inner) => inner,
+            }
+        }
+
+        fn snapshot(&self) -> Self {
+            match self {
+                Self::Memory(inner) => Self::Memory(inner.snapshot()),
+                Self::Os(inner) => Self::Os(inner.snapshot()),
+            }
+        }
+    }
+
+    pub(crate) struct TestCaseBuilder {
+        db: TestDb,
+        src: FileSystemPathBuf,
+        custom_typeshed: FileSystemPathBuf,
+        site_packages: FileSystemPathBuf,
+        target_version: Option<TargetVersion>,
+    }
+
+    impl TestCaseBuilder {
+        #[must_use]
+        pub(crate) fn with_target_version(mut self, target_version: TargetVersion) -> Self {
+            self.target_version = Some(target_version);
+            self
+        }
+
+        pub(crate) fn build(self) -> TestCase {
+            let TestCaseBuilder {
+                mut db,
+                src,
+                custom_typeshed,
+                site_packages,
+                target_version,
+            } = self;
+
+            let settings = RawModuleResolutionSettings {
+                target_version: target_version.unwrap_or_default(),
+                extra_paths: vec![],
+                workspace_root: src.clone(),
+                custom_typeshed: Some(custom_typeshed.clone()),
+                site_packages: Some(site_packages.clone()),
+            };
+
+            set_module_resolution_settings(&mut db, settings);
+
+            TestCase {
+                db,
+                src,
+                custom_typeshed,
+                site_packages,
+            }
+        }
+    }
+
+    pub(crate) struct TestCase {
+        pub(crate) db: TestDb,
+        pub(crate) src: FileSystemPathBuf,
+        pub(crate) custom_typeshed: FileSystemPathBuf,
+        pub(crate) site_packages: FileSystemPathBuf,
+    }
+
+    pub(crate) fn create_resolver_builder() -> std::io::Result<TestCaseBuilder> {
+        static VERSIONS_DATA: &str = "\
+        asyncio: 3.8-               # 'Regular' package on py38+
+        asyncio.tasks: 3.9-3.11
+        collections: 3.9-           # 'Regular' package on py39+
+        functools: 3.8-
+        importlib: 3.9-             # Namespace package on py39+
+        xml: 3.8-3.8                # Namespace package on py38 only
+        ";
+
+        let db = TestDb::new();
+
+        let src = FileSystemPathBuf::from("src");
+        let site_packages = FileSystemPathBuf::from("site_packages");
+        let custom_typeshed = FileSystemPathBuf::from("typeshed");
+
+        let fs = db.memory_file_system();
+
+        fs.create_directory_all(&src)?;
+        fs.create_directory_all(&site_packages)?;
+        fs.create_directory_all(&custom_typeshed)?;
+        fs.write_file(custom_typeshed.join("stdlib/VERSIONS"), VERSIONS_DATA)?;
+
+        // Regular package on py38+
+        fs.create_directory_all(custom_typeshed.join("stdlib/asyncio"))?;
+        fs.touch(custom_typeshed.join("stdlib/asyncio/__init__.pyi"))?;
+        fs.write_file(
+            custom_typeshed.join("stdlib/asyncio/tasks.pyi"),
+            "class Task: ...",
+        )?;
+
+        // Regular package on py39+
+        fs.create_directory_all(custom_typeshed.join("stdlib/collections"))?;
+        fs.touch(custom_typeshed.join("stdlib/collections/__init__.pyi"))?;
+
+        // Namespace package on py38 only
+        fs.create_directory_all(custom_typeshed.join("stdlib/xml"))?;
+        fs.touch(custom_typeshed.join("stdlib/xml/etree.pyi"))?;
+
+        // Namespace package on py39+
+        fs.create_directory_all(custom_typeshed.join("stdlib/importlib"))?;
+        fs.touch(custom_typeshed.join("stdlib/importlib/abc.pyi"))?;
+
+        fs.write_file(
+            custom_typeshed.join("stdlib/functools.pyi"),
+            "def update_wrapper(): ...",
+        )?;
+
+        Ok(TestCaseBuilder {
+            db,
+            src,
+            custom_typeshed,
+            site_packages,
+            target_version: None,
+        })
+    }
+}

crates/red_knot_module_resolver/src/lib.rs

@@ -0,0 +1,15 @@
+mod db;
+mod module;
+mod module_name;
+mod path;
+mod resolver;
+mod state;
+mod supported_py_version;
+mod typeshed;
+
+pub use db::{Db, Jar};
+pub use module::{Module, ModuleKind};
+pub use module_name::ModuleName;
+pub use resolver::{resolve_module, set_module_resolution_settings, RawModuleResolutionSettings};
+pub use supported_py_version::TargetVersion;
+pub use typeshed::{TypeshedVersionsParseError, TypeshedVersionsParseErrorKind};

crates/red_knot_module_resolver/src/module.rs

@@ -0,0 +1,91 @@
+use std::fmt::Formatter;
+use std::sync::Arc;
+
+use ruff_db::vfs::VfsFile;
+
+use crate::db::Db;
+use crate::module_name::ModuleName;
+use crate::path::{ModuleResolutionPathBuf, ModuleResolutionPathRef};
+
+/// Representation of a Python module.
+#[derive(Clone, PartialEq, Eq)]
+pub struct Module {
+    inner: Arc<ModuleInner>,
+}
+
+impl Module {
+    pub(crate) fn new(
+        name: ModuleName,
+        kind: ModuleKind,
+        search_path: Arc<ModuleResolutionPathBuf>,
+        file: VfsFile,
+    ) -> Self {
+        Self {
+            inner: Arc::new(ModuleInner {
+                name,
+                kind,
+                search_path,
+                file,
+            }),
+        }
+    }
+
+    /// The absolute name of the module (e.g. `foo.bar`)
+    pub fn name(&self) -> &ModuleName {
+        &self.inner.name
+    }
+
+    /// The file to the source code that defines this module
+    pub fn file(&self) -> VfsFile {
+        self.inner.file
+    }
+
+    /// The search path from which the module was resolved.
+    pub(crate) fn search_path(&self) -> ModuleResolutionPathRef {
+        ModuleResolutionPathRef::from(&*self.inner.search_path)
+    }
+
+    /// Determine whether this module is a single-file module or a package
+    pub fn kind(&self) -> ModuleKind {
+        self.inner.kind
+    }
+}
+
+impl std::fmt::Debug for Module {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Module")
+            .field("name", &self.name())
+            .field("kind", &self.kind())
+            .field("file", &self.file())
+            .field("search_path", &self.search_path())
+            .finish()
+    }
+}
+
+impl salsa::DebugWithDb<dyn Db> for Module {
+    fn fmt(&self, f: &mut Formatter<'_>, db: &dyn Db) -> std::fmt::Result {
+        f.debug_struct("Module")
+            .field("name", &self.name())
+            .field("kind", &self.kind())
+            .field("file", &self.file().debug(db.upcast()))
+            .field("search_path", &self.search_path())
+            .finish()
+    }
+}
+
+#[derive(PartialEq, Eq)]
+struct ModuleInner {
+    name: ModuleName,
+    kind: ModuleKind,
+    search_path: Arc<ModuleResolutionPathBuf>,
+    file: VfsFile,
+}
+
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
+pub enum ModuleKind {
+    /// A single-file module (e.g. `foo.py` or `foo.pyi`)
+    Module,
+
+    /// A python package (`foo/__init__.py` or `foo/__init__.pyi`)
+    Package,
+}

crates/red_knot_module_resolver/src/module_name.rs

@@ -42,7 +42,7 @@ impl ModuleName {
     /// ## Examples
     ///
     /// ```
-    /// use red_knot_python_semantic::ModuleName;
+    /// use red_knot_module_resolver::ModuleName;
     ///
     /// assert_eq!(ModuleName::new_static("foo.bar").as_deref(), Some("foo.bar"));
     /// assert_eq!(ModuleName::new_static(""), None);
@@ -55,7 +55,8 @@ impl ModuleName {
     #[inline]
     #[must_use]
     pub fn new_static(name: &'static str) -> Option<Self> {
-        Self::is_valid_name(name).then(|| Self(CompactString::const_new(name)))
+        // TODO(Micha): Use CompactString::const_new once we upgrade to 0.8 https://github.com/ParkMyCar/compact_str/pull/336
+        Self::is_valid_name(name).then(|| Self(CompactString::from(name)))
     }
 
     #[must_use]
@@ -68,7 +69,7 @@ impl ModuleName {
     /// # Examples
     ///
     /// ```
-    /// use red_knot_python_semantic::ModuleName;
+    /// use red_knot_module_resolver::ModuleName;
     ///
     /// assert_eq!(ModuleName::new_static("foo.bar.baz").unwrap().components().collect::<Vec<_>>(), vec!["foo", "bar", "baz"]);
     /// ```
@@ -82,7 +83,7 @@ impl ModuleName {
     /// # Examples
     ///
     /// ```
-    /// use red_knot_python_semantic::ModuleName;
+    /// use red_knot_module_resolver::ModuleName;
     ///
     /// assert_eq!(ModuleName::new_static("foo.bar").unwrap().parent(), Some(ModuleName::new_static("foo").unwrap()));
     /// assert_eq!(ModuleName::new_static("foo.bar.baz").unwrap().parent(), Some(ModuleName::new_static("foo.bar").unwrap()));
@@ -101,7 +102,7 @@ impl ModuleName {
     /// # Examples
     ///
     /// ```
-    /// use red_knot_python_semantic::ModuleName;
+    /// use red_knot_module_resolver::ModuleName;
     ///
     /// assert!(ModuleName::new_static("foo.bar").unwrap().starts_with(&ModuleName::new_static("foo").unwrap()));
     ///
@@ -133,7 +134,7 @@ impl ModuleName {
     /// # Examples
     ///
     /// ```
-    /// use red_knot_python_semantic::ModuleName;
+    /// use red_knot_module_resolver::ModuleName;
     ///
     /// assert_eq!(&*ModuleName::from_components(["a"]).unwrap(), "a");
     /// assert_eq!(&*ModuleName::from_components(["a", "b"]).unwrap(), "a.b");
@@ -168,44 +169,6 @@ impl ModuleName {
         };
         Some(Self(name))
     }
-
-    /// Extend `self` with the components of `other`
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use red_knot_python_semantic::ModuleName;
-    ///
-    /// let mut module_name = ModuleName::new_static("foo").unwrap();
-    /// module_name.extend(&ModuleName::new_static("bar").unwrap());
-    /// assert_eq!(&module_name, "foo.bar");
-    /// module_name.extend(&ModuleName::new_static("baz.eggs.ham").unwrap());
-    /// assert_eq!(&module_name, "foo.bar.baz.eggs.ham");
-    /// ```
-    pub fn extend(&mut self, other: &ModuleName) {
-        self.0.push('.');
-        self.0.push_str(other);
-    }
-
-    /// Returns an iterator of this module name and all of its parent modules.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use red_knot_python_semantic::ModuleName;
-    ///
-    /// assert_eq!(
-    ///     ModuleName::new_static("foo.bar.baz").unwrap().ancestors().collect::<Vec<_>>(),
-    ///     vec![
-    ///         ModuleName::new_static("foo.bar.baz").unwrap(),
-    ///         ModuleName::new_static("foo.bar").unwrap(),
-    ///         ModuleName::new_static("foo").unwrap(),
-    ///     ],
-    /// );
-    /// ```
-    pub fn ancestors(&self) -> impl Iterator<Item = Self> {
-        std::iter::successors(Some(self.clone()), Self::parent)
-    }
 }
 
 impl Deref for ModuleName {

crates/red_knot_module_resolver/src/path.rs

@@ -0,0 +1,997 @@
+/// Internal abstractions for differentiating between different kinds of search paths.
+///
+/// TODO(Alex): Should we use different types for absolute vs relative paths?
+/// <https://github.com/astral-sh/ruff/pull/12141#discussion_r1667010245>
+use std::fmt;
+
+use ruff_db::file_system::{FileSystemPath, FileSystemPathBuf};
+use ruff_db::vfs::{system_path_to_file, VfsFile};
+
+use crate::module_name::ModuleName;
+use crate::state::ResolverState;
+use crate::typeshed::TypeshedVersionsQueryResult;
+
+/// Enumeration of the different kinds of search paths type checkers are expected to support.
+///
+/// N.B. Although we don't implement `Ord` for this enum, they are ordered in terms of the
+/// priority that we want to give these modules when resolving them,
+/// as per [the order given in the typing spec]
+///
+/// [the order given in the typing spec]: https://typing.readthedocs.io/en/latest/spec/distributing.html#import-resolution-ordering
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+enum ModuleResolutionPathBufInner {
+    Extra(FileSystemPathBuf),
+    FirstParty(FileSystemPathBuf),
+    StandardLibrary(FileSystemPathBuf),
+    SitePackages(FileSystemPathBuf),
+}
+
+impl ModuleResolutionPathBufInner {
+    fn push(&mut self, component: &str) {
+        let extension = camino::Utf8Path::new(component).extension();
+        let inner = match self {
+            Self::Extra(ref mut path) => {
+                if let Some(extension) = extension {
+                    assert!(
+                        matches!(extension, "pyi" | "py"),
+                        "Extension must be `py` or `pyi`; got `{extension}`"
+                    );
+                }
+                path
+            }
+            Self::FirstParty(ref mut path) => {
+                if let Some(extension) = extension {
+                    assert!(
+                        matches!(extension, "pyi" | "py"),
+                        "Extension must be `py` or `pyi`; got `{extension}`"
+                    );
+                }
+                path
+            }
+            Self::StandardLibrary(ref mut path) => {
+                if let Some(extension) = extension {
+                    assert_eq!(
+                        extension, "pyi",
+                        "Extension must be `pyi`; got `{extension}`"
+                    );
+                }
+                path
+            }
+            Self::SitePackages(ref mut path) => {
+                if let Some(extension) = extension {
+                    assert!(
+                        matches!(extension, "pyi" | "py"),
+                        "Extension must be `py` or `pyi`; got `{extension}`"
+                    );
+                }
+                path
+            }
+        };
+        assert!(
+            inner.extension().is_none(),
+            "Cannot push part {component} to {inner}, which already has an extension"
+        );
+        inner.push(component);
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Hash)]
+pub(crate) struct ModuleResolutionPathBuf(ModuleResolutionPathBufInner);
+
+impl ModuleResolutionPathBuf {
+    /// Push a new part to the path,
+    /// while maintaining the invariant that the path can only have `.py` or `.pyi` extensions.
+    /// For the stdlib variant specifically, it may only have a `.pyi` extension.
+    ///
+    /// ## Panics:
+    /// If a component with an invalid extension is passed
+    pub(crate) fn push(&mut self, component: &str) {
+        self.0.push(component);
+    }
+
+    #[must_use]
+    pub(crate) fn extra(path: impl Into<FileSystemPathBuf>) -> Option<Self> {
+        let path = path.into();
+        path.extension()
+            .map_or(true, |ext| matches!(ext, "py" | "pyi"))
+            .then_some(Self(ModuleResolutionPathBufInner::Extra(path)))
+    }
+
+    #[must_use]
+    pub(crate) fn first_party(path: impl Into<FileSystemPathBuf>) -> Option<Self> {
+        let path = path.into();
+        path.extension()
+            .map_or(true, |ext| matches!(ext, "pyi" | "py"))
+            .then_some(Self(ModuleResolutionPathBufInner::FirstParty(path)))
+    }
+
+    #[must_use]
+    pub(crate) fn standard_library(path: impl Into<FileSystemPathBuf>) -> Option<Self> {
+        let path = path.into();
+        path.extension()
+            .map_or(true, |ext| ext == "pyi")
+            .then_some(Self(ModuleResolutionPathBufInner::StandardLibrary(path)))
+    }
+
+    #[must_use]
+    pub(crate) fn stdlib_from_typeshed_root(typeshed_root: &FileSystemPath) -> Option<Self> {
+        Self::standard_library(typeshed_root.join(FileSystemPath::new("stdlib")))
+    }
+
+    #[must_use]
+    pub(crate) fn site_packages(path: impl Into<FileSystemPathBuf>) -> Option<Self> {
+        let path = path.into();
+        path.extension()
+            .map_or(true, |ext| matches!(ext, "pyi" | "py"))
+            .then_some(Self(ModuleResolutionPathBufInner::SitePackages(path)))
+    }
+
+    #[must_use]
+    pub(crate) fn is_regular_package(&self, search_path: &Self, resolver: &ResolverState) -> bool {
+        ModuleResolutionPathRef::from(self).is_regular_package(search_path, resolver)
+    }
+
+    #[must_use]
+    pub(crate) fn is_directory(&self, search_path: &Self, resolver: &ResolverState) -> bool {
+        ModuleResolutionPathRef::from(self).is_directory(search_path, resolver)
+    }
+
+    #[must_use]
+    pub(crate) fn with_pyi_extension(&self) -> Self {
+        ModuleResolutionPathRef::from(self).with_pyi_extension()
+    }
+
+    #[must_use]
+    pub(crate) fn with_py_extension(&self) -> Option<Self> {
+        ModuleResolutionPathRef::from(self).with_py_extension()
+    }
+
+    #[must_use]
+    pub(crate) fn relativize_path<'a>(
+        &'a self,
+        absolute_path: &'a (impl AsRef<FileSystemPath> + ?Sized),
+    ) -> Option<ModuleResolutionPathRef<'a>> {
+        ModuleResolutionPathRef::from(self).relativize_path(absolute_path.as_ref())
+    }
+
+    /// Returns `None` if the path doesn't exist, isn't accessible, or if the path points to a directory.
+    pub(crate) fn to_vfs_file(
+        &self,
+        search_path: &Self,
+        resolver: &ResolverState,
+    ) -> Option<VfsFile> {
+        ModuleResolutionPathRef::from(self).to_vfs_file(search_path, resolver)
+    }
+}
+
+impl fmt::Debug for ModuleResolutionPathBuf {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let (name, path) = match &self.0 {
+            ModuleResolutionPathBufInner::Extra(path) => ("Extra", path),
+            ModuleResolutionPathBufInner::FirstParty(path) => ("FirstParty", path),
+            ModuleResolutionPathBufInner::SitePackages(path) => ("SitePackages", path),
+            ModuleResolutionPathBufInner::StandardLibrary(path) => ("StandardLibrary", path),
+        };
+        f.debug_tuple(&format!("ModuleResolutionPathBuf::{name}"))
+            .field(path)
+            .finish()
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash, Clone, Copy)]
+enum ModuleResolutionPathRefInner<'a> {
+    Extra(&'a FileSystemPath),
+    FirstParty(&'a FileSystemPath),
+    StandardLibrary(&'a FileSystemPath),
+    SitePackages(&'a FileSystemPath),
+}
+
+impl<'a> ModuleResolutionPathRefInner<'a> {
+    #[must_use]
+    fn query_stdlib_version<'db>(
+        module_path: &'a FileSystemPath,
+        stdlib_search_path: Self,
+        stdlib_root: &FileSystemPath,
+        resolver_state: &ResolverState<'db>,
+    ) -> TypeshedVersionsQueryResult {
+        let Some(module_name) = stdlib_search_path
+            .relativize_path(module_path)
+            .and_then(Self::to_module_name)
+        else {
+            return TypeshedVersionsQueryResult::DoesNotExist;
+        };
+        let ResolverState {
+            db,
+            typeshed_versions,
+            target_version,
+        } = resolver_state;
+        typeshed_versions.query_module(&module_name, *db, stdlib_root, *target_version)
+    }
+
+    #[must_use]
+    fn is_directory(&self, search_path: Self, resolver: &ResolverState) -> bool {
+        match (self, search_path) {
+            (Self::Extra(path), Self::Extra(_)) => resolver.file_system().is_directory(path),
+            (Self::FirstParty(path), Self::FirstParty(_)) => resolver.file_system().is_directory(path),
+            (Self::SitePackages(path), Self::SitePackages(_)) => resolver.file_system().is_directory(path),
+            (Self::StandardLibrary(path), Self::StandardLibrary(stdlib_root)) => {
+                match Self::query_stdlib_version( path, search_path, stdlib_root, resolver) {
+                    TypeshedVersionsQueryResult::DoesNotExist => false,
+                    TypeshedVersionsQueryResult::Exists => resolver.file_system().is_directory(path),
+                    TypeshedVersionsQueryResult::MaybeExists => resolver.file_system().is_directory(path),
+                }
+            }
+            (path, root) => unreachable!(
+                "The search path should always be the same variant as `self` (got: {path:?}, {root:?})"
+            )
+        }
+    }
+
+    #[must_use]
+    fn is_regular_package(&self, search_path: Self, resolver: &ResolverState) -> bool {
+        fn is_non_stdlib_pkg(state: &ResolverState, path: &FileSystemPath) -> bool {
+            let file_system = state.file_system();
+            file_system.exists(&path.join("__init__.py"))
+                || file_system.exists(&path.join("__init__.pyi"))
+        }
+
+        match (self, search_path) {
+            (Self::Extra(path), Self::Extra(_)) => is_non_stdlib_pkg(resolver, path),
+            (Self::FirstParty(path), Self::FirstParty(_)) => is_non_stdlib_pkg(resolver, path),
+            (Self::SitePackages(path), Self::SitePackages(_)) => is_non_stdlib_pkg(resolver, path),
+            // Unlike the other variants:
+            // (1) Account for VERSIONS
+            // (2) Only test for `__init__.pyi`, not `__init__.py`
+            (Self::StandardLibrary(path), Self::StandardLibrary(stdlib_root)) => {
+                match Self::query_stdlib_version( path, search_path, stdlib_root, resolver) {
+                    TypeshedVersionsQueryResult::DoesNotExist => false,
+                    TypeshedVersionsQueryResult::Exists => resolver.db.file_system().exists(&path.join("__init__.pyi")),
+                    TypeshedVersionsQueryResult::MaybeExists => resolver.db.file_system().exists(&path.join("__init__.pyi")),
+                }
+            }
+            (path, root) => unreachable!(
+                "The search path should always be the same variant as `self` (got: {path:?}, {root:?})"
+            )
+        }
+    }
+
+    fn to_vfs_file(self, search_path: Self, resolver: &ResolverState) -> Option<VfsFile> {
+        match (self, search_path) {
+            (Self::Extra(path), Self::Extra(_)) => system_path_to_file(resolver.db.upcast(), path),
+            (Self::FirstParty(path), Self::FirstParty(_)) => system_path_to_file(resolver.db.upcast(), path),
+            (Self::SitePackages(path), Self::SitePackages(_)) => {
+                system_path_to_file(resolver.db.upcast(), path)
+            }
+            (Self::StandardLibrary(path), Self::StandardLibrary(stdlib_root)) => {
+                match Self::query_stdlib_version(path, search_path, stdlib_root, resolver) {
+                    TypeshedVersionsQueryResult::DoesNotExist => None,
+                    TypeshedVersionsQueryResult::Exists => system_path_to_file(resolver.db.upcast(), path),
+                    TypeshedVersionsQueryResult::MaybeExists => system_path_to_file(resolver.db.upcast(), path)
+                }
+            }
+            (path, root) => unreachable!(
+                "The search path should always be the same variant as `self` (got: {path:?}, {root:?})"
+            )
+        }
+    }
+
+    #[must_use]
+    fn to_module_name(self) -> Option<ModuleName> {
+        let (fs_path, skip_final_part) = match self {
+            Self::Extra(path) | Self::FirstParty(path) | Self::SitePackages(path) => (
+                path,
+                path.ends_with("__init__.py") || path.ends_with("__init__.pyi"),
+            ),
+            Self::StandardLibrary(path) => (path, path.ends_with("__init__.pyi")),
+        };
+
+        let parent_components = fs_path
+            .parent()?
+            .components()
+            .map(|component| component.as_str());
+
+        if skip_final_part {
+            ModuleName::from_components(parent_components)
+        } else {
+            ModuleName::from_components(parent_components.chain(fs_path.file_stem()))
+        }
+    }
+
+    #[must_use]
+    fn with_pyi_extension(&self) -> ModuleResolutionPathBufInner {
+        match self {
+            Self::Extra(path) => ModuleResolutionPathBufInner::Extra(path.with_extension("pyi")),
+            Self::FirstParty(path) => {
+                ModuleResolutionPathBufInner::FirstParty(path.with_extension("pyi"))
+            }
+            Self::StandardLibrary(path) => {
+                ModuleResolutionPathBufInner::StandardLibrary(path.with_extension("pyi"))
+            }
+            Self::SitePackages(path) => {
+                ModuleResolutionPathBufInner::SitePackages(path.with_extension("pyi"))
+            }
+        }
+    }
+
+    #[must_use]
+    fn with_py_extension(&self) -> Option<ModuleResolutionPathBufInner> {
+        match self {
+            Self::Extra(path) => Some(ModuleResolutionPathBufInner::Extra(
+                path.with_extension("py"),
+            )),
+            Self::FirstParty(path) => Some(ModuleResolutionPathBufInner::FirstParty(
+                path.with_extension("py"),
+            )),
+            Self::StandardLibrary(_) => None,
+            Self::SitePackages(path) => Some(ModuleResolutionPathBufInner::SitePackages(
+                path.with_extension("py"),
+            )),
+        }
+    }
+
+    #[must_use]
+    fn relativize_path(&self, absolute_path: &'a FileSystemPath) -> Option<Self> {
+        match self {
+            Self::Extra(root) => absolute_path.strip_prefix(root).ok().and_then(|path| {
+                path.extension()
+                    .map_or(true, |ext| matches!(ext, "py" | "pyi"))
+                    .then_some(Self::Extra(path))
+            }),
+            Self::FirstParty(root) => absolute_path.strip_prefix(root).ok().and_then(|path| {
+                path.extension()
+                    .map_or(true, |ext| matches!(ext, "pyi" | "py"))
+                    .then_some(Self::FirstParty(path))
+            }),
+            Self::StandardLibrary(root) => absolute_path.strip_prefix(root).ok().and_then(|path| {
+                path.extension()
+                    .map_or(true, |ext| ext == "pyi")
+                    .then_some(Self::StandardLibrary(path))
+            }),
+            Self::SitePackages(root) => absolute_path.strip_prefix(root).ok().and_then(|path| {
+                path.extension()
+                    .map_or(true, |ext| matches!(ext, "pyi" | "py"))
+                    .then_some(Self::SitePackages(path))
+            }),
+        }
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub(crate) struct ModuleResolutionPathRef<'a>(ModuleResolutionPathRefInner<'a>);
+
+impl<'a> ModuleResolutionPathRef<'a> {
+    #[must_use]
+    pub(crate) fn is_directory(
+        &self,
+        search_path: impl Into<Self>,
+        resolver: &ResolverState,
+    ) -> bool {
+        self.0.is_directory(search_path.into().0, resolver)
+    }
+
+    #[must_use]
+    pub(crate) fn is_regular_package(
+        &self,
+        search_path: impl Into<Self>,
+        resolver: &ResolverState,
+    ) -> bool {
+        self.0.is_regular_package(search_path.into().0, resolver)
+    }
+
+    #[must_use]
+    pub(crate) fn to_vfs_file(
+        self,
+        search_path: impl Into<Self>,
+        resolver: &ResolverState,
+    ) -> Option<VfsFile> {
+        self.0.to_vfs_file(search_path.into().0, resolver)
+    }
+
+    #[must_use]
+    pub(crate) fn to_module_name(self) -> Option<ModuleName> {
+        self.0.to_module_name()
+    }
+
+    #[must_use]
+    pub(crate) fn with_pyi_extension(&self) -> ModuleResolutionPathBuf {
+        ModuleResolutionPathBuf(self.0.with_pyi_extension())
+    }
+
+    #[must_use]
+    pub(crate) fn with_py_extension(self) -> Option<ModuleResolutionPathBuf> {
+        self.0.with_py_extension().map(ModuleResolutionPathBuf)
+    }
+
+    #[must_use]
+    pub(crate) fn relativize_path(&self, absolute_path: &'a FileSystemPath) -> Option<Self> {
+        self.0.relativize_path(absolute_path).map(Self)
+    }
+}
+
+impl fmt::Debug for ModuleResolutionPathRef<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let (name, path) = match &self.0 {
+            ModuleResolutionPathRefInner::Extra(path) => ("Extra", path),
+            ModuleResolutionPathRefInner::FirstParty(path) => ("FirstParty", path),
+            ModuleResolutionPathRefInner::SitePackages(path) => ("SitePackages", path),
+            ModuleResolutionPathRefInner::StandardLibrary(path) => ("StandardLibrary", path),
+        };
+        f.debug_tuple(&format!("ModuleResolutionPathRef::{name}"))
+            .field(path)
+            .finish()
+    }
+}
+
+impl<'a> From<&'a ModuleResolutionPathBuf> for ModuleResolutionPathRef<'a> {
+    fn from(value: &'a ModuleResolutionPathBuf) -> Self {
+        let inner = match &value.0 {
+            ModuleResolutionPathBufInner::Extra(path) => ModuleResolutionPathRefInner::Extra(path),
+            ModuleResolutionPathBufInner::FirstParty(path) => {
+                ModuleResolutionPathRefInner::FirstParty(path)
+            }
+            ModuleResolutionPathBufInner::StandardLibrary(path) => {
+                ModuleResolutionPathRefInner::StandardLibrary(path)
+            }
+            ModuleResolutionPathBufInner::SitePackages(path) => {
+                ModuleResolutionPathRefInner::SitePackages(path)
+            }
+        };
+        ModuleResolutionPathRef(inner)
+    }
+}
+
+impl PartialEq<FileSystemPath> for ModuleResolutionPathRef<'_> {
+    fn eq(&self, other: &FileSystemPath) -> bool {
+        let fs_path = match self.0 {
+            ModuleResolutionPathRefInner::Extra(path) => path,
+            ModuleResolutionPathRefInner::FirstParty(path) => path,
+            ModuleResolutionPathRefInner::SitePackages(path) => path,
+            ModuleResolutionPathRefInner::StandardLibrary(path) => path,
+        };
+        fs_path == other
+    }
+}
+
+impl PartialEq<ModuleResolutionPathRef<'_>> for FileSystemPath {
+    fn eq(&self, other: &ModuleResolutionPathRef) -> bool {
+        other == self
+    }
+}
+
+impl PartialEq<FileSystemPathBuf> for ModuleResolutionPathRef<'_> {
+    fn eq(&self, other: &FileSystemPathBuf) -> bool {
+        self == &**other
+    }
+}
+
+impl PartialEq<ModuleResolutionPathRef<'_>> for FileSystemPathBuf {
+    fn eq(&self, other: &ModuleResolutionPathRef<'_>) -> bool {
+        &**self == other
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use insta::assert_debug_snapshot;
+
+    use crate::db::tests::{create_resolver_builder, TestCase, TestDb};
+    use crate::supported_py_version::TargetVersion;
+    use crate::typeshed::LazyTypeshedVersions;
+
+    use super::*;
+
+    impl ModuleResolutionPathBuf {
+        #[must_use]
+        pub(crate) fn join(&self, component: &str) -> Self {
+            ModuleResolutionPathRef::from(self).join(component)
+        }
+    }
+
+    impl<'a> ModuleResolutionPathRef<'a> {
+        #[must_use]
+        fn join(
+            &self,
+            component: &'a (impl AsRef<FileSystemPath> + ?Sized),
+        ) -> ModuleResolutionPathBuf {
+            let mut result = self.to_path_buf();
+            result.push(component.as_ref().as_str());
+            result
+        }
+
+        #[must_use]
+        pub(crate) fn to_path_buf(self) -> ModuleResolutionPathBuf {
+            let inner = match self.0 {
+                ModuleResolutionPathRefInner::Extra(path) => {
+                    ModuleResolutionPathBufInner::Extra(path.to_path_buf())
+                }
+                ModuleResolutionPathRefInner::FirstParty(path) => {
+                    ModuleResolutionPathBufInner::FirstParty(path.to_path_buf())
+                }
+                ModuleResolutionPathRefInner::StandardLibrary(path) => {
+                    ModuleResolutionPathBufInner::StandardLibrary(path.to_path_buf())
+                }
+                ModuleResolutionPathRefInner::SitePackages(path) => {
+                    ModuleResolutionPathBufInner::SitePackages(path.to_path_buf())
+                }
+            };
+            ModuleResolutionPathBuf(inner)
+        }
+
+        #[must_use]
+        pub(crate) const fn is_stdlib_search_path(&self) -> bool {
+            matches!(&self.0, ModuleResolutionPathRefInner::StandardLibrary(_))
+        }
+    }
+
+    #[test]
+    fn constructor_rejects_non_pyi_stdlib_paths() {
+        assert_eq!(ModuleResolutionPathBuf::standard_library("foo.py"), None);
+        assert_eq!(
+            ModuleResolutionPathBuf::standard_library("foo/__init__.py"),
+            None
+        );
+    }
+
+    #[test]
+    fn path_buf_debug_impl() {
+        assert_debug_snapshot!(
+            ModuleResolutionPathBuf::standard_library("foo/bar.pyi").unwrap(),
+            @r###"
+        ModuleResolutionPathBuf::StandardLibrary(
+            "foo/bar.pyi",
+        )
+        "###
+        );
+    }
+
+    #[test]
+    fn path_ref_debug_impl() {
+        assert_debug_snapshot!(
+            ModuleResolutionPathRef(ModuleResolutionPathRefInner::Extra(FileSystemPath::new("foo/bar.py"))),
+            @r###"
+        ModuleResolutionPathRef::Extra(
+            "foo/bar.py",
+        )
+        "###
+        );
+    }
+
+    #[test]
+    fn with_extension_methods() {
+        assert_eq!(
+            ModuleResolutionPathBuf::standard_library("foo")
+                .unwrap()
+                .with_py_extension(),
+            None
+        );
+
+        assert_eq!(
+            ModuleResolutionPathBuf::standard_library("foo")
+                .unwrap()
+                .with_pyi_extension(),
+            ModuleResolutionPathBuf(ModuleResolutionPathBufInner::StandardLibrary(
+                FileSystemPathBuf::from("foo.pyi")
+            ))
+        );
+
+        assert_eq!(
+            ModuleResolutionPathBuf::first_party("foo/bar")
+                .unwrap()
+                .with_py_extension()
+                .unwrap(),
+            ModuleResolutionPathBuf(ModuleResolutionPathBufInner::FirstParty(
+                FileSystemPathBuf::from("foo/bar.py")
+            ))
+        );
+    }
+
+    #[test]
+    fn module_name_1_part() {
+        assert_eq!(
+            ModuleResolutionPathRef(ModuleResolutionPathRefInner::Extra(FileSystemPath::new(
+                "foo"
+            )))
+            .to_module_name(),
+            ModuleName::new_static("foo")
+        );
+
+        assert_eq!(
+            ModuleResolutionPathRef(ModuleResolutionPathRefInner::StandardLibrary(
+                FileSystemPath::new("foo.pyi")
+            ))
+            .to_module_name(),
+            ModuleName::new_static("foo")
+        );
+
+        assert_eq!(
+            ModuleResolutionPathRef(ModuleResolutionPathRefInner::FirstParty(
+                FileSystemPath::new("foo/__init__.py")
+            ))
+            .to_module_name(),
+            ModuleName::new_static("foo")
+        );
+    }
+
+    #[test]
+    fn module_name_2_parts() {
+        assert_eq!(
+            ModuleResolutionPathRef(ModuleResolutionPathRefInner::StandardLibrary(
+                FileSystemPath::new("foo/bar")
+            ))
+            .to_module_name(),
+            ModuleName::new_static("foo.bar")
+        );
+
+        assert_eq!(
+            ModuleResolutionPathRef(ModuleResolutionPathRefInner::Extra(FileSystemPath::new(
+                "foo/bar.pyi"
+            )))
+            .to_module_name(),
+            ModuleName::new_static("foo.bar")
+        );
+
+        assert_eq!(
+            ModuleResolutionPathRef(ModuleResolutionPathRefInner::SitePackages(
+                FileSystemPath::new("foo/bar/__init__.pyi")
+            ))
+            .to_module_name(),
+            ModuleName::new_static("foo.bar")
+        );
+    }
+
+    #[test]
+    fn module_name_3_parts() {
+        assert_eq!(
+            ModuleResolutionPathRef(ModuleResolutionPathRefInner::SitePackages(
+                FileSystemPath::new("foo/bar/__init__.pyi")
+            ))
+            .to_module_name(),
+            ModuleName::new_static("foo.bar")
+        );
+
+        assert_eq!(
+            ModuleResolutionPathRef(ModuleResolutionPathRefInner::SitePackages(
+                FileSystemPath::new("foo/bar/baz")
+            ))
+            .to_module_name(),
+            ModuleName::new_static("foo.bar.baz")
+        );
+    }
+
+    #[test]
+    fn join() {
+        assert_eq!(
+            ModuleResolutionPathBuf::standard_library("foo")
+                .unwrap()
+                .join("bar"),
+            ModuleResolutionPathBuf(ModuleResolutionPathBufInner::StandardLibrary(
+                FileSystemPathBuf::from("foo/bar")
+            ))
+        );
+        assert_eq!(
+            ModuleResolutionPathBuf::standard_library("foo")
+                .unwrap()
+                .join("bar.pyi"),
+            ModuleResolutionPathBuf(ModuleResolutionPathBufInner::StandardLibrary(
+                FileSystemPathBuf::from("foo/bar.pyi")
+            ))
+        );
+        assert_eq!(
+            ModuleResolutionPathBuf::extra("foo")
+                .unwrap()
+                .join("bar.py"),
+            ModuleResolutionPathBuf(ModuleResolutionPathBufInner::Extra(
+                FileSystemPathBuf::from("foo/bar.py")
+            ))
+        );
+    }
+
+    #[test]
+    #[should_panic(expected = "Extension must be `pyi`; got `py`")]
+    fn stdlib_path_invalid_join_py() {
+        ModuleResolutionPathBuf::standard_library("foo")
+            .unwrap()
+            .push("bar.py");
+    }
+
+    #[test]
+    #[should_panic(expected = "Extension must be `pyi`; got `rs`")]
+    fn stdlib_path_invalid_join_rs() {
+        ModuleResolutionPathBuf::standard_library("foo")
+            .unwrap()
+            .push("bar.rs");
+    }
+
+    #[test]
+    #[should_panic(expected = "Extension must be `py` or `pyi`; got `rs`")]
+    fn non_stdlib_path_invalid_join_rs() {
+        ModuleResolutionPathBuf::site_packages("foo")
+            .unwrap()
+            .push("bar.rs");
+    }
+
+    #[test]
+    #[should_panic(expected = "already has an extension")]
+    fn invalid_stdlib_join_too_many_extensions() {
+        ModuleResolutionPathBuf::standard_library("foo.pyi")
+            .unwrap()
+            .push("bar.pyi");
+    }
+
+    #[test]
+    fn relativize_stdlib_path_errors() {
+        let root = ModuleResolutionPathBuf::standard_library("foo/stdlib").unwrap();
+
+        // Must have a `.pyi` extension or no extension:
+        let bad_absolute_path = FileSystemPath::new("foo/stdlib/x.py");
+        assert_eq!(root.relativize_path(bad_absolute_path), None);
+        let second_bad_absolute_path = FileSystemPath::new("foo/stdlib/x.rs");
+        assert_eq!(root.relativize_path(second_bad_absolute_path), None);
+
+        // Must be a path that is a child of `root`:
+        let third_bad_absolute_path = FileSystemPath::new("bar/stdlib/x.pyi");
+        assert_eq!(root.relativize_path(third_bad_absolute_path), None);
+    }
+
+    #[test]
+    fn relativize_non_stdlib_path_errors() {
+        let root = ModuleResolutionPathBuf::extra("foo/stdlib").unwrap();
+        // Must have a `.py` extension, a `.pyi` extension, or no extension:
+        let bad_absolute_path = FileSystemPath::new("foo/stdlib/x.rs");
+        assert_eq!(root.relativize_path(bad_absolute_path), None);
+        // Must be a path that is a child of `root`:
+        let second_bad_absolute_path = FileSystemPath::new("bar/stdlib/x.pyi");
+        assert_eq!(root.relativize_path(second_bad_absolute_path), None);
+    }
+
+    #[test]
+    fn relativize_path() {
+        assert_eq!(
+            ModuleResolutionPathBuf::standard_library("foo/baz")
+                .unwrap()
+                .relativize_path("foo/baz/eggs/__init__.pyi")
+                .unwrap(),
+            ModuleResolutionPathRef(ModuleResolutionPathRefInner::StandardLibrary(
+                FileSystemPath::new("eggs/__init__.pyi")
+            ))
+        );
+    }
+
+    fn py38_stdlib_test_case() -> (TestDb, ModuleResolutionPathBuf) {
+        let TestCase {
+            db,
+            custom_typeshed,
+            ..
+        } = create_resolver_builder().unwrap().build();
+        let stdlib_module_path =
+            ModuleResolutionPathBuf::stdlib_from_typeshed_root(&custom_typeshed).unwrap();
+        (db, stdlib_module_path)
+    }
+
+    #[test]
+    fn mocked_typeshed_existing_regular_stdlib_pkg_py38() {
+        let (db, stdlib_path) = py38_stdlib_test_case();
+        let resolver = ResolverState {
+            db: &db,
+            typeshed_versions: LazyTypeshedVersions::new(),
+            target_version: TargetVersion::Py38,
+        };
+
+        let asyncio_regular_package = stdlib_path.join("asyncio");
+        assert!(asyncio_regular_package.is_directory(&stdlib_path, &resolver));
+        assert!(asyncio_regular_package.is_regular_package(&stdlib_path, &resolver));
+        // Paths to directories don't resolve to VfsFiles
+        assert_eq!(
+            asyncio_regular_package.to_vfs_file(&stdlib_path, &resolver),
+            None
+        );
+        assert!(asyncio_regular_package
+            .join("__init__.pyi")
+            .to_vfs_file(&stdlib_path, &resolver)
+            .is_some());
+
+        // The `asyncio` package exists on Python 3.8, but the `asyncio.tasks` submodule does not,
+        // according to the `VERSIONS` file in our typeshed mock:
+        let asyncio_tasks_module = stdlib_path.join("asyncio/tasks.pyi");
+        assert_eq!(
+            asyncio_tasks_module.to_vfs_file(&stdlib_path, &resolver),
+            None
+        );
+        assert!(!asyncio_tasks_module.is_directory(&stdlib_path, &resolver));
+        assert!(!asyncio_tasks_module.is_regular_package(&stdlib_path, &resolver));
+    }
+
+    #[test]
+    fn mocked_typeshed_existing_namespace_stdlib_pkg_py38() {
+        let (db, stdlib_path) = py38_stdlib_test_case();
+        let resolver = ResolverState {
+            db: &db,
+            typeshed_versions: LazyTypeshedVersions::new(),
+            target_version: TargetVersion::Py38,
+        };
+
+        let xml_namespace_package = stdlib_path.join("xml");
+        assert!(xml_namespace_package.is_directory(&stdlib_path, &resolver));
+        // Paths to directories don't resolve to VfsFiles
+        assert_eq!(
+            xml_namespace_package.to_vfs_file(&stdlib_path, &resolver),
+            None
+        );
+        assert!(!xml_namespace_package.is_regular_package(&stdlib_path, &resolver));
+
+        let xml_etree = stdlib_path.join("xml/etree.pyi");
+        assert!(!xml_etree.is_directory(&stdlib_path, &resolver));
+        assert!(xml_etree.to_vfs_file(&stdlib_path, &resolver).is_some());
+        assert!(!xml_etree.is_regular_package(&stdlib_path, &resolver));
+    }
+
+    #[test]
+    fn mocked_typeshed_single_file_stdlib_module_py38() {
+        let (db, stdlib_path) = py38_stdlib_test_case();
+        let resolver = ResolverState {
+            db: &db,
+            typeshed_versions: LazyTypeshedVersions::new(),
+            target_version: TargetVersion::Py38,
+        };
+
+        let functools_module = stdlib_path.join("functools.pyi");
+        assert!(functools_module
+            .to_vfs_file(&stdlib_path, &resolver)
+            .is_some());
+        assert!(!functools_module.is_directory(&stdlib_path, &resolver));
+        assert!(!functools_module.is_regular_package(&stdlib_path, &resolver));
+    }
+
+    #[test]
+    fn mocked_typeshed_nonexistent_regular_stdlib_pkg_py38() {
+        let (db, stdlib_path) = py38_stdlib_test_case();
+        let resolver = ResolverState {
+            db: &db,
+            typeshed_versions: LazyTypeshedVersions::new(),
+            target_version: TargetVersion::Py38,
+        };
+
+        let collections_regular_package = stdlib_path.join("collections");
+        assert_eq!(
+            collections_regular_package.to_vfs_file(&stdlib_path, &resolver),
+            None
+        );
+        assert!(!collections_regular_package.is_directory(&stdlib_path, &resolver));
+        assert!(!collections_regular_package.is_regular_package(&stdlib_path, &resolver));
+    }
+
+    #[test]
+    fn mocked_typeshed_nonexistent_namespace_stdlib_pkg_py38() {
+        let (db, stdlib_path) = py38_stdlib_test_case();
+        let resolver = ResolverState {
+            db: &db,
+            typeshed_versions: LazyTypeshedVersions::new(),
+            target_version: TargetVersion::Py38,
+        };
+
+        let importlib_namespace_package = stdlib_path.join("importlib");
+        assert_eq!(
+            importlib_namespace_package.to_vfs_file(&stdlib_path, &resolver),
+            None
+        );
+        assert!(!importlib_namespace_package.is_directory(&stdlib_path, &resolver));
+        assert!(!importlib_namespace_package.is_regular_package(&stdlib_path, &resolver));
+
+        let importlib_abc = stdlib_path.join("importlib/abc.pyi");
+        assert_eq!(importlib_abc.to_vfs_file(&stdlib_path, &resolver), None);
+        assert!(!importlib_abc.is_directory(&stdlib_path, &resolver));
+        assert!(!importlib_abc.is_regular_package(&stdlib_path, &resolver));
+    }
+
+    #[test]
+    fn mocked_typeshed_nonexistent_single_file_module_py38() {
+        let (db, stdlib_path) = py38_stdlib_test_case();
+        let resolver = ResolverState {
+            db: &db,
+            typeshed_versions: LazyTypeshedVersions::new(),
+            target_version: TargetVersion::Py38,
+        };
+
+        let non_existent = stdlib_path.join("doesnt_even_exist");
+        assert_eq!(non_existent.to_vfs_file(&stdlib_path, &resolver), None);
+        assert!(!non_existent.is_directory(&stdlib_path, &resolver));
+        assert!(!non_existent.is_regular_package(&stdlib_path, &resolver));
+    }
+
+    fn py39_stdlib_test_case() -> (TestDb, ModuleResolutionPathBuf) {
+        let TestCase {
+            db,
+            custom_typeshed,
+            ..
+        } = create_resolver_builder()
+            .unwrap()
+            .with_target_version(TargetVersion::Py39)
+            .build();
+        let stdlib_module_path =
+            ModuleResolutionPathBuf::stdlib_from_typeshed_root(&custom_typeshed).unwrap();
+        (db, stdlib_module_path)
+    }
+
+    #[test]
+    fn mocked_typeshed_existing_regular_stdlib_pkgs_py39() {
+        let (db, stdlib_path) = py39_stdlib_test_case();
+        let resolver = ResolverState {
+            db: &db,
+            typeshed_versions: LazyTypeshedVersions::new(),
+            target_version: TargetVersion::Py39,
+        };
+
+        // Since we've set the target version to Py39,
+        // `collections` should now exist as a directory, according to VERSIONS...
+        let collections_regular_package = stdlib_path.join("collections");
+        assert!(collections_regular_package.is_directory(&stdlib_path, &resolver));
+        assert!(collections_regular_package.is_regular_package(&stdlib_path, &resolver));
+        // (This is still `None`, as directories don't resolve to `Vfs` files)
+        assert_eq!(
+            collections_regular_package.to_vfs_file(&stdlib_path, &resolver),
+            None
+        );
+        assert!(collections_regular_package
+            .join("__init__.pyi")
+            .to_vfs_file(&stdlib_path, &resolver)
+            .is_some());
+
+        // ...and so should the `asyncio.tasks` submodule (though it's still not a directory):
+        let asyncio_tasks_module = stdlib_path.join("asyncio/tasks.pyi");
+        assert!(asyncio_tasks_module
+            .to_vfs_file(&stdlib_path, &resolver)
+            .is_some());
+        assert!(!asyncio_tasks_module.is_directory(&stdlib_path, &resolver));
+        assert!(!asyncio_tasks_module.is_regular_package(&stdlib_path, &resolver));
+    }
+
+    #[test]
+    fn mocked_typeshed_existing_namespace_stdlib_pkg_py39() {
+        let (db, stdlib_path) = py39_stdlib_test_case();
+        let resolver = ResolverState {
+            db: &db,
+            typeshed_versions: LazyTypeshedVersions::new(),
+            target_version: TargetVersion::Py39,
+        };
+
+        // The `importlib` directory now also exists...
+        let importlib_namespace_package = stdlib_path.join("importlib");
+        assert!(importlib_namespace_package.is_directory(&stdlib_path, &resolver));
+        assert!(!importlib_namespace_package.is_regular_package(&stdlib_path, &resolver));
+        // (This is still `None`, as directories don't resolve to `Vfs` files)
+        assert_eq!(
+            importlib_namespace_package.to_vfs_file(&stdlib_path, &resolver),
+            None
+        );
+
+        // ...As do submodules in the `importlib` namespace package:
+        let importlib_abc = importlib_namespace_package.join("abc.pyi");
+        assert!(!importlib_abc.is_directory(&stdlib_path, &resolver));
+        assert!(!importlib_abc.is_regular_package(&stdlib_path, &resolver));
+        assert!(importlib_abc.to_vfs_file(&stdlib_path, &resolver).is_some());
+    }
+
+    #[test]
+    fn mocked_typeshed_nonexistent_namespace_stdlib_pkg_py39() {
+        let (db, stdlib_path) = py39_stdlib_test_case();
+        let resolver = ResolverState {
+            db: &db,
+            typeshed_versions: LazyTypeshedVersions::new(),
+            target_version: TargetVersion::Py39,
+        };
+
+        // The `xml` package no longer exists on py39:
+        let xml_namespace_package = stdlib_path.join("xml");
+        assert_eq!(
+            xml_namespace_package.to_vfs_file(&stdlib_path, &resolver),
+            None
+        );
+        assert!(!xml_namespace_package.is_directory(&stdlib_path, &resolver));
+        assert!(!xml_namespace_package.is_regular_package(&stdlib_path, &resolver));
+
+        let xml_etree = xml_namespace_package.join("etree.pyi");
+        assert_eq!(xml_etree.to_vfs_file(&stdlib_path, &resolver), None);
+        assert!(!xml_etree.is_directory(&stdlib_path, &resolver));
+        assert!(!xml_etree.is_regular_package(&stdlib_path, &resolver));
+    }
+}

crates/red_knot_module_resolver/src/resolver.rs

@@ -0,0 +1,985 @@
+use std::ops::Deref;
+use std::sync::Arc;
+
+use ruff_db::file_system::FileSystemPathBuf;
+use ruff_db::vfs::{vfs_path_to_file, VfsFile, VfsPath};
+
+use crate::db::Db;
+use crate::module::{Module, ModuleKind};
+use crate::module_name::ModuleName;
+use crate::path::ModuleResolutionPathBuf;
+use crate::resolver::internal::ModuleResolverSettings;
+use crate::state::ResolverState;
+use crate::supported_py_version::TargetVersion;
+
+/// Configures the module resolver settings.
+///
+/// Must be called before calling any other module resolution functions.
+pub fn set_module_resolution_settings(db: &mut dyn Db, config: RawModuleResolutionSettings) {
+    // There's no concurrency issue here because we hold a `&mut dyn Db` reference. No other
+    // thread can mutate the `Db` while we're in this call, so using `try_get` to test if
+    // the settings have already been set is safe.
+    let resolved_settings = config.into_configuration_settings();
+    if let Some(existing) = ModuleResolverSettings::try_get(db) {
+        existing.set_settings(db).to(resolved_settings);
+    } else {
+        ModuleResolverSettings::new(db, resolved_settings);
+    }
+}
+
+/// Resolves a module name to a module.
+pub fn resolve_module(db: &dyn Db, module_name: ModuleName) -> Option<Module> {
+    let interned_name = internal::ModuleNameIngredient::new(db, module_name);
+
+    resolve_module_query(db, interned_name)
+}
+
+/// Salsa query that resolves an interned [`ModuleNameIngredient`] to a module.
+///
+/// This query should not be called directly. Instead, use [`resolve_module`]. It only exists
+/// because Salsa requires the module name to be an ingredient.
+#[salsa::tracked]
+pub(crate) fn resolve_module_query<'db>(
+    db: &'db dyn Db,
+    module_name: internal::ModuleNameIngredient<'db>,
+) -> Option<Module> {
+    let _span = tracing::trace_span!("resolve_module", ?module_name).entered();
+
+    let name = module_name.name(db);
+
+    let (search_path, module_file, kind) = resolve_name(db, name)?;
+
+    let module = Module::new(name.clone(), kind, search_path, module_file);
+
+    Some(module)
+}
+
+/// Resolves the module for the given path.
+///
+/// Returns `None` if the path is not a module locatable via any of the known search paths.
+#[allow(unused)]
+pub(crate) fn path_to_module(db: &dyn Db, path: &VfsPath) -> Option<Module> {
+    // It's not entirely clear on first sight why this method calls `file_to_module` instead of
+    // it being the other way round, considering that the first thing that `file_to_module` does
+    // is to retrieve the file's path.
+    //
+    // The reason is that `file_to_module` is a tracked Salsa query and salsa queries require that
+    // all arguments are Salsa ingredients (something stored in Salsa). `Path`s aren't salsa ingredients but
+    // `VfsFile` is. So what we do here is to retrieve the `path`'s `VfsFile` so that we can make
+    // use of Salsa's caching and invalidation.
+    let file = vfs_path_to_file(db.upcast(), path)?;
+    file_to_module(db, file)
+}
+
+/// Resolves the module for the file with the given id.
+///
+/// Returns `None` if the file is not a module locatable via any of the known search paths.
+#[salsa::tracked]
+pub(crate) fn file_to_module(db: &dyn Db, file: VfsFile) -> Option<Module> {
+    let _span = tracing::trace_span!("file_to_module", ?file).entered();
+
+    let VfsPath::FileSystem(path) = file.path(db.upcast()) else {
+        todo!("VendoredPaths are not yet supported")
+    };
+
+    let resolver_settings = module_resolver_settings(db);
+
+    let relative_path = resolver_settings
+        .search_paths()
+        .iter()
+        .find_map(|root| root.relativize_path(path))?;
+
+    let module_name = relative_path.to_module_name()?;
+
+    // Resolve the module name to see if Python would resolve the name to the same path.
+    // If it doesn't, then that means that multiple modules have the same name in different
+    // root paths, but that the module corresponding to `path` is in a lower priority search path,
+    // in which case we ignore it.
+    let module = resolve_module(db, module_name)?;
+
+    if file == module.file() {
+        Some(module)
+    } else {
+        // This path is for a module with the same name but with a different precedence. For example:
+        // ```
+        // src/foo.py
+        // src/foo/__init__.py
+        // ```
+        // The module name of `src/foo.py` is `foo`, but the module loaded by Python is `src/foo/__init__.py`.
+        // That means we need to ignore `src/foo.py` even though it resolves to the same module name.
+        None
+    }
+}
+
+/// "Raw" configuration settings for module resolution: unvalidated, unnormalized
+#[derive(Eq, PartialEq, Debug)]
+pub struct RawModuleResolutionSettings {
+    /// The target Python version the user has specified
+    pub target_version: TargetVersion,
+
+    /// List of user-provided paths that should take first priority in the module resolution.
+    /// Examples in other type checkers are mypy's MYPYPATH environment variable,
+    /// or pyright's stubPath configuration setting.
+    pub extra_paths: Vec<FileSystemPathBuf>,
+
+    /// The root of the workspace, used for finding first-party modules.
+    pub workspace_root: FileSystemPathBuf,
+
+    /// Optional (already validated) path to standard-library typeshed stubs.
+    /// If this is not provided, we will fallback to our vendored typeshed stubs
+    /// bundled as a zip file in the binary
+    pub custom_typeshed: Option<FileSystemPathBuf>,
+
+    /// The path to the user's `site-packages` directory, where third-party packages from ``PyPI`` are installed.
+    pub site_packages: Option<FileSystemPathBuf>,
+}
+
+impl RawModuleResolutionSettings {
+    /// Implementation of the typing spec's [module resolution order]
+    ///
+    /// TODO(Alex): this method does multiple `.unwrap()` calls when it should really return an error.
+    /// Each `.unwrap()` call is a point where we're validating a setting that the user would pass
+    /// and transforming it into an internal representation for a validated path.
+    /// Rather than panicking if a path fails to validate, we should display an error message to the user
+    /// and exit the process with a nonzero exit code.
+    /// This validation should probably be done outside of Salsa?
+    ///
+    /// [module resolution order]: https://typing.readthedocs.io/en/latest/spec/distributing.html#import-resolution-ordering
+    fn into_configuration_settings(self) -> ModuleResolutionSettings {
+        let RawModuleResolutionSettings {
+            target_version,
+            extra_paths,
+            workspace_root,
+            site_packages,
+            custom_typeshed,
+        } = self;
+
+        let mut paths: Vec<ModuleResolutionPathBuf> = extra_paths
+            .into_iter()
+            .map(|fs_path| ModuleResolutionPathBuf::extra(fs_path).unwrap())
+            .collect();
+
+        paths.push(ModuleResolutionPathBuf::first_party(workspace_root).unwrap());
+
+        if let Some(custom_typeshed) = custom_typeshed {
+            paths.push(
+                ModuleResolutionPathBuf::stdlib_from_typeshed_root(&custom_typeshed).unwrap(),
+            );
+        }
+
+        // TODO vendor typeshed's third-party stubs as well as the stdlib and fallback to them as a final step
+        if let Some(site_packages) = site_packages {
+            paths.push(ModuleResolutionPathBuf::site_packages(site_packages).unwrap());
+        }
+
+        ModuleResolutionSettings {
+            target_version,
+            search_paths: OrderedSearchPaths(paths.into_iter().map(Arc::new).collect()),
+        }
+    }
+}
+
+/// A resolved module resolution order as per the [typing spec]
+///
+/// [typing spec]: https://typing.readthedocs.io/en/latest/spec/distributing.html#import-resolution-ordering
+#[derive(Clone, Debug, Default, Eq, PartialEq)]
+pub(crate) struct OrderedSearchPaths(Vec<Arc<ModuleResolutionPathBuf>>);
+
+impl Deref for OrderedSearchPaths {
+    type Target = [Arc<ModuleResolutionPathBuf>];
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub(crate) struct ModuleResolutionSettings {
+    search_paths: OrderedSearchPaths,
+    target_version: TargetVersion,
+}
+
+impl ModuleResolutionSettings {
+    pub(crate) fn search_paths(&self) -> &[Arc<ModuleResolutionPathBuf>] {
+        &self.search_paths
+    }
+
+    pub(crate) fn target_version(&self) -> TargetVersion {
+        self.target_version
+    }
+}
+
+// The singleton methods generated by salsa are all `pub` instead of `pub(crate)` which triggers
+// `unreachable_pub`. Work around this by creating a module and allow `unreachable_pub` for it.
+// Salsa also generates uses to `_db` variables for `interned` which triggers `clippy::used_underscore_binding`. Suppress that too
+// TODO(micha): Contribute a fix for this upstream where the singleton methods have the same visibility as the struct.
+#[allow(unreachable_pub, clippy::used_underscore_binding)]
+pub(crate) mod internal {
+    use crate::module_name::ModuleName;
+    use crate::resolver::ModuleResolutionSettings;
+
+    #[salsa::input(singleton)]
+    pub(crate) struct ModuleResolverSettings {
+        #[return_ref]
+        pub(super) settings: ModuleResolutionSettings,
+    }
+
+    /// A thin wrapper around `ModuleName` to make it a Salsa ingredient.
+    ///
+    /// This is needed because Salsa requires that all query arguments are salsa ingredients.
+    #[salsa::interned]
+    pub(crate) struct ModuleNameIngredient<'db> {
+        #[return_ref]
+        pub(super) name: ModuleName,
+    }
+}
+
+fn module_resolver_settings(db: &dyn Db) -> &ModuleResolutionSettings {
+    ModuleResolverSettings::get(db).settings(db)
+}
+
+/// Given a module name and a list of search paths in which to lookup modules,
+/// attempt to resolve the module name
+fn resolve_name(
+    db: &dyn Db,
+    name: &ModuleName,
+) -> Option<(Arc<ModuleResolutionPathBuf>, VfsFile, ModuleKind)> {
+    let resolver_settings = module_resolver_settings(db);
+    let resolver_state = ResolverState::new(db, resolver_settings.target_version());
+
+    for search_path in resolver_settings.search_paths() {
+        let mut components = name.components();
+        let module_name = components.next_back()?;
+
+        match resolve_package(search_path, components, &resolver_state) {
+            Ok(resolved_package) => {
+                let mut package_path = resolved_package.path;
+
+                package_path.push(module_name);
+
+                // Must be a `__init__.pyi` or `__init__.py` or it isn't a package.
+                let kind = if package_path.is_directory(search_path, &resolver_state) {
+                    package_path.push("__init__");
+                    ModuleKind::Package
+                } else {
+                    ModuleKind::Module
+                };
+
+                // TODO Implement full https://peps.python.org/pep-0561/#type-checker-module-resolution-order resolution
+                if let Some(stub) = package_path
+                    .with_pyi_extension()
+                    .to_vfs_file(search_path, &resolver_state)
+                {
+                    return Some((search_path.clone(), stub, kind));
+                }
+
+                if let Some(module) = package_path
+                    .with_py_extension()
+                    .and_then(|path| path.to_vfs_file(search_path, &resolver_state))
+                {
+                    return Some((search_path.clone(), module, kind));
+                }
+
+                // For regular packages, don't search the next search path. All files of that
+                // package must be in the same location
+                if resolved_package.kind.is_regular_package() {
+                    return None;
+                }
+            }
+            Err(parent_kind) => {
+                if parent_kind.is_regular_package() {
+                    // For regular packages, don't search the next search path.
+                    return None;
+                }
+            }
+        }
+    }
+
+    None
+}
+
+fn resolve_package<'a, 'db, I>(
+    module_search_path: &ModuleResolutionPathBuf,
+    components: I,
+    resolver_state: &ResolverState<'db>,
+) -> Result<ResolvedPackage, PackageKind>
+where
+    I: Iterator<Item = &'a str>,
+{
+    let mut package_path = module_search_path.clone();
+
+    // `true` if inside a folder that is a namespace package (has no `__init__.py`).
+    // Namespace packages are special because they can be spread across multiple search paths.
+    // https://peps.python.org/pep-0420/
+    let mut in_namespace_package = false;
+
+    // `true` if resolving a sub-package. For example, `true` when resolving `bar` of `foo.bar`.
+    let mut in_sub_package = false;
+
+    // For `foo.bar.baz`, test that `foo` and `baz` both contain a `__init__.py`.
+    for folder in components {
+        package_path.push(folder);
+
+        let is_regular_package =
+            package_path.is_regular_package(module_search_path, resolver_state);
+
+        if is_regular_package {
+            in_namespace_package = false;
+        } else if package_path.is_directory(module_search_path, resolver_state) {
+            // A directory without an `__init__.py` is a namespace package, continue with the next folder.
+            in_namespace_package = true;
+        } else if in_namespace_package {
+            // Package not found but it is part of a namespace package.
+            return Err(PackageKind::Namespace);
+        } else if in_sub_package {
+            // A regular sub package wasn't found.
+            return Err(PackageKind::Regular);
+        } else {
+            // We couldn't find `foo` for `foo.bar.baz`, search the next search path.
+            return Err(PackageKind::Root);
+        }
+
+        in_sub_package = true;
+    }
+
+    let kind = if in_namespace_package {
+        PackageKind::Namespace
+    } else if in_sub_package {
+        PackageKind::Regular
+    } else {
+        PackageKind::Root
+    };
+
+    Ok(ResolvedPackage {
+        kind,
+        path: package_path,
+    })
+}
+
+#[derive(Debug)]
+struct ResolvedPackage {
+    path: ModuleResolutionPathBuf,
+    kind: PackageKind,
+}
+
+#[derive(Copy, Clone, Eq, PartialEq, Debug)]
+enum PackageKind {
+    /// A root package or module. E.g. `foo` in `foo.bar.baz` or just `foo`.
+    Root,
+
+    /// A regular sub-package where the parent contains an `__init__.py`.
+    ///
+    /// For example, `bar` in `foo.bar` when the `foo` directory contains an `__init__.py`.
+    Regular,
+
+    /// A sub-package in a namespace package. A namespace package is a package without an `__init__.py`.
+    ///
+    /// For example, `bar` in `foo.bar` if the `foo` directory contains no `__init__.py`.
+    Namespace,
+}
+
+impl PackageKind {
+    const fn is_regular_package(self) -> bool {
+        matches!(self, PackageKind::Regular)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use ruff_db::file_system::FileSystemPath;
+    use ruff_db::vfs::{system_path_to_file, VfsFile, VfsPath};
+
+    use crate::db::tests::{create_resolver_builder, TestCase};
+    use crate::module::ModuleKind;
+    use crate::module_name::ModuleName;
+
+    use super::*;
+
+    fn setup_resolver_test() -> TestCase {
+        create_resolver_builder().unwrap().build()
+    }
+
+    #[test]
+    fn first_party_module() -> anyhow::Result<()> {
+        let TestCase { db, src, .. } = setup_resolver_test();
+
+        let foo_module_name = ModuleName::new_static("foo").unwrap();
+        let foo_path = src.join("foo.py");
+        db.memory_file_system()
+            .write_file(&foo_path, "print('Hello, world!')")?;
+
+        let foo_module = resolve_module(&db, foo_module_name.clone()).unwrap();
+
+        assert_eq!(
+            Some(&foo_module),
+            resolve_module(&db, foo_module_name.clone()).as_ref()
+        );
+
+        assert_eq!("foo", foo_module.name());
+        assert_eq!(&src, &foo_module.search_path());
+        assert_eq!(ModuleKind::Module, foo_module.kind());
+
+        assert_eq!(&foo_path, foo_module.file().path(&db));
+        assert_eq!(
+            Some(foo_module),
+            path_to_module(&db, &VfsPath::FileSystem(foo_path))
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn stdlib() {
+        let TestCase {
+            db,
+            custom_typeshed,
+            ..
+        } = setup_resolver_test();
+
+        let stdlib_dir =
+            ModuleResolutionPathBuf::stdlib_from_typeshed_root(&custom_typeshed).unwrap();
+        let functools_module_name = ModuleName::new_static("functools").unwrap();
+        let functools_module = resolve_module(&db, functools_module_name.clone()).unwrap();
+
+        assert_eq!(
+            Some(&functools_module),
+            resolve_module(&db, functools_module_name).as_ref()
+        );
+
+        assert_eq!(stdlib_dir, functools_module.search_path().to_path_buf());
+        assert_eq!(ModuleKind::Module, functools_module.kind());
+
+        let expected_functools_path =
+            VfsPath::FileSystem(custom_typeshed.join("stdlib/functools.pyi"));
+        assert_eq!(&expected_functools_path, functools_module.file().path(&db));
+
+        assert_eq!(
+            Some(functools_module),
+            path_to_module(&db, &expected_functools_path)
+        );
+    }
+
+    fn create_module_names(raw_names: &[&str]) -> Vec<ModuleName> {
+        raw_names
+            .iter()
+            .map(|raw| ModuleName::new(raw).unwrap())
+            .collect()
+    }
+
+    #[test]
+    fn stdlib_resolution_respects_versions_file_py38_existing_modules() {
+        let TestCase {
+            db,
+            custom_typeshed,
+            ..
+        } = setup_resolver_test();
+
+        let existing_modules = create_module_names(&["asyncio", "functools", "xml.etree"]);
+        for module_name in existing_modules {
+            let resolved_module = resolve_module(&db, module_name.clone()).unwrap_or_else(|| {
+                panic!("Expected module {module_name} to exist in the mock stdlib")
+            });
+            let search_path = resolved_module.search_path();
+            assert_eq!(
+                &custom_typeshed.join("stdlib"),
+                &search_path,
+                "Search path for {module_name} was unexpectedly {search_path:?}"
+            );
+            assert!(
+                search_path.is_stdlib_search_path(),
+                "Expected a stdlib search path, but got {search_path:?}"
+            );
+        }
+    }
+
+    #[test]
+    fn stdlib_resolution_respects_versions_file_py38_nonexisting_modules() {
+        let TestCase { db, .. } = setup_resolver_test();
+        let nonexisting_modules = create_module_names(&[
+            "collections",
+            "importlib",
+            "importlib.abc",
+            "xml",
+            "asyncio.tasks",
+        ]);
+        for module_name in nonexisting_modules {
+            assert!(
+                resolve_module(&db, module_name.clone()).is_none(),
+                "Unexpectedly resolved a module for {module_name}"
+            );
+        }
+    }
+
+    #[test]
+    fn stdlib_resolution_respects_versions_file_py39_existing_modules() {
+        let TestCase {
+            db,
+            custom_typeshed,
+            ..
+        } = create_resolver_builder()
+            .unwrap()
+            .with_target_version(TargetVersion::Py39)
+            .build();
+
+        let existing_modules = create_module_names(&[
+            "asyncio",
+            "functools",
+            "importlib.abc",
+            "collections",
+            "asyncio.tasks",
+        ]);
+        for module_name in existing_modules {
+            let resolved_module = resolve_module(&db, module_name.clone()).unwrap_or_else(|| {
+                panic!("Expected module {module_name} to exist in the mock stdlib")
+            });
+            let search_path = resolved_module.search_path();
+            assert_eq!(
+                &custom_typeshed.join("stdlib"),
+                &search_path,
+                "Search path for {module_name} was unexpectedly {search_path:?}"
+            );
+            assert!(
+                search_path.is_stdlib_search_path(),
+                "Expected a stdlib search path, but got {search_path:?}"
+            );
+        }
+    }
+    #[test]
+    fn stdlib_resolution_respects_versions_file_py39_nonexisting_modules() {
+        let TestCase { db, .. } = create_resolver_builder()
+            .unwrap()
+            .with_target_version(TargetVersion::Py39)
+            .build();
+
+        let nonexisting_modules = create_module_names(&["importlib", "xml", "xml.etree"]);
+        for module_name in nonexisting_modules {
+            assert!(
+                resolve_module(&db, module_name.clone()).is_none(),
+                "Unexpectedly resolved a module for {module_name}"
+            );
+        }
+    }
+
+    #[test]
+    fn first_party_precedence_over_stdlib() -> anyhow::Result<()> {
+        let TestCase { db, src, .. } = setup_resolver_test();
+
+        let first_party_functools_path = src.join("functools.py");
+        db.memory_file_system()
+            .write_file(&first_party_functools_path, "def update_wrapper(): ...")?;
+
+        let functools_module_name = ModuleName::new_static("functools").unwrap();
+        let functools_module = resolve_module(&db, functools_module_name.clone()).unwrap();
+
+        assert_eq!(
+            Some(&functools_module),
+            resolve_module(&db, functools_module_name).as_ref()
+        );
+        assert_eq!(&src, &functools_module.search_path());
+        assert_eq!(ModuleKind::Module, functools_module.kind());
+        assert_eq!(
+            &first_party_functools_path,
+            functools_module.file().path(&db)
+        );
+
+        assert_eq!(
+            Some(functools_module),
+            path_to_module(&db, &VfsPath::FileSystem(first_party_functools_path))
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn resolve_package() -> anyhow::Result<()> {
+        let TestCase { src, db, .. } = setup_resolver_test();
+
+        let foo_dir = src.join("foo");
+        let foo_path = foo_dir.join("__init__.py");
+
+        db.memory_file_system()
+            .write_file(&foo_path, "print('Hello, world!')")?;
+
+        let foo_module = resolve_module(&db, ModuleName::new_static("foo").unwrap()).unwrap();
+
+        assert_eq!("foo", foo_module.name());
+        assert_eq!(&src, &foo_module.search_path());
+        assert_eq!(&foo_path, foo_module.file().path(&db));
+
+        assert_eq!(
+            Some(&foo_module),
+            path_to_module(&db, &VfsPath::FileSystem(foo_path)).as_ref()
+        );
+
+        // Resolving by directory doesn't resolve to the init file.
+        assert_eq!(None, path_to_module(&db, &VfsPath::FileSystem(foo_dir)));
+
+        Ok(())
+    }
+
+    #[test]
+    fn package_priority_over_module() -> anyhow::Result<()> {
+        let TestCase { db, src, .. } = setup_resolver_test();
+
+        let foo_dir = src.join("foo");
+        let foo_init = foo_dir.join("__init__.py");
+
+        db.memory_file_system()
+            .write_file(&foo_init, "print('Hello, world!')")?;
+
+        let foo_py = src.join("foo.py");
+        db.memory_file_system()
+            .write_file(&foo_py, "print('Hello, world!')")?;
+
+        let foo_module = resolve_module(&db, ModuleName::new_static("foo").unwrap()).unwrap();
+
+        assert_eq!(&src, &foo_module.search_path());
+        assert_eq!(&foo_init, foo_module.file().path(&db));
+        assert_eq!(ModuleKind::Package, foo_module.kind());
+
+        assert_eq!(
+            Some(foo_module),
+            path_to_module(&db, &VfsPath::FileSystem(foo_init))
+        );
+        assert_eq!(None, path_to_module(&db, &VfsPath::FileSystem(foo_py)));
+
+        Ok(())
+    }
+
+    #[test]
+    fn typing_stub_over_module() -> anyhow::Result<()> {
+        let TestCase { db, src, .. } = setup_resolver_test();
+
+        let foo_stub = src.join("foo.pyi");
+        let foo_py = src.join("foo.py");
+        db.memory_file_system()
+            .write_files([(&foo_stub, "x: int"), (&foo_py, "print('Hello, world!')")])?;
+
+        let foo = resolve_module(&db, ModuleName::new_static("foo").unwrap()).unwrap();
+
+        assert_eq!(&src, &foo.search_path());
+        assert_eq!(&foo_stub, foo.file().path(&db));
+
+        assert_eq!(
+            Some(foo),
+            path_to_module(&db, &VfsPath::FileSystem(foo_stub))
+        );
+        assert_eq!(None, path_to_module(&db, &VfsPath::FileSystem(foo_py)));
+
+        Ok(())
+    }
+
+    #[test]
+    fn sub_packages() -> anyhow::Result<()> {
+        let TestCase { db, src, .. } = setup_resolver_test();
+
+        let foo = src.join("foo");
+        let bar = foo.join("bar");
+        let baz = bar.join("baz.py");
+
+        db.memory_file_system().write_files([
+            (&foo.join("__init__.py"), ""),
+            (&bar.join("__init__.py"), ""),
+            (&baz, "print('Hello, world!')"),
+        ])?;
+
+        let baz_module =
+            resolve_module(&db, ModuleName::new_static("foo.bar.baz").unwrap()).unwrap();
+
+        assert_eq!(&src, &baz_module.search_path());
+        assert_eq!(&baz, baz_module.file().path(&db));
+
+        assert_eq!(
+            Some(baz_module),
+            path_to_module(&db, &VfsPath::FileSystem(baz))
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn namespace_package() -> anyhow::Result<()> {
+        let TestCase {
+            db,
+            src,
+            site_packages,
+            ..
+        } = setup_resolver_test();
+
+        // From [PEP420](https://peps.python.org/pep-0420/#nested-namespace-packages).
+        // But uses `src` for `project1` and `site_packages2` for `project2`.
+        // ```
+        // src
+        //   parent
+        //     child
+        //       one.py
+        // site_packages
+        //   parent
+        //     child
+        //       two.py
+        // ```
+
+        let parent1 = src.join("parent");
+        let child1 = parent1.join("child");
+        let one = child1.join("one.py");
+
+        let parent2 = site_packages.join("parent");
+        let child2 = parent2.join("child");
+        let two = child2.join("two.py");
+
+        db.memory_file_system().write_files([
+            (&one, "print('Hello, world!')"),
+            (&two, "print('Hello, world!')"),
+        ])?;
+
+        let one_module =
+            resolve_module(&db, ModuleName::new_static("parent.child.one").unwrap()).unwrap();
+
+        assert_eq!(
+            Some(one_module),
+            path_to_module(&db, &VfsPath::FileSystem(one))
+        );
+
+        let two_module =
+            resolve_module(&db, ModuleName::new_static("parent.child.two").unwrap()).unwrap();
+        assert_eq!(
+            Some(two_module),
+            path_to_module(&db, &VfsPath::FileSystem(two))
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn regular_package_in_namespace_package() -> anyhow::Result<()> {
+        let TestCase {
+            db,
+            src,
+            site_packages,
+            ..
+        } = setup_resolver_test();
+
+        // Adopted test case from the [PEP420 examples](https://peps.python.org/pep-0420/#nested-namespace-packages).
+        // The `src/parent/child` package is a regular package. Therefore, `site_packages/parent/child/two.py` should not be resolved.
+        // ```
+        // src
+        //   parent
+        //     child
+        //       one.py
+        // site_packages
+        //   parent
+        //     child
+        //       two.py
+        // ```
+
+        let parent1 = src.join("parent");
+        let child1 = parent1.join("child");
+        let one = child1.join("one.py");
+
+        let parent2 = site_packages.join("parent");
+        let child2 = parent2.join("child");
+        let two = child2.join("two.py");
+
+        db.memory_file_system().write_files([
+            (&child1.join("__init__.py"), "print('Hello, world!')"),
+            (&one, "print('Hello, world!')"),
+            (&two, "print('Hello, world!')"),
+        ])?;
+
+        let one_module =
+            resolve_module(&db, ModuleName::new_static("parent.child.one").unwrap()).unwrap();
+
+        assert_eq!(
+            Some(one_module),
+            path_to_module(&db, &VfsPath::FileSystem(one))
+        );
+
+        assert_eq!(
+            None,
+            resolve_module(&db, ModuleName::new_static("parent.child.two").unwrap())
+        );
+        Ok(())
+    }
+
+    #[test]
+    fn module_search_path_priority() -> anyhow::Result<()> {
+        let TestCase {
+            db,
+            src,
+            site_packages,
+            ..
+        } = setup_resolver_test();
+
+        let foo_src = src.join("foo.py");
+        let foo_site_packages = site_packages.join("foo.py");
+
+        db.memory_file_system()
+            .write_files([(&foo_src, ""), (&foo_site_packages, "")])?;
+
+        let foo_module = resolve_module(&db, ModuleName::new_static("foo").unwrap()).unwrap();
+
+        assert_eq!(&src, &foo_module.search_path());
+        assert_eq!(&foo_src, foo_module.file().path(&db));
+
+        assert_eq!(
+            Some(foo_module),
+            path_to_module(&db, &VfsPath::FileSystem(foo_src))
+        );
+        assert_eq!(
+            None,
+            path_to_module(&db, &VfsPath::FileSystem(foo_site_packages))
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    #[cfg(target_family = "unix")]
+    fn symlink() -> anyhow::Result<()> {
+        let TestCase {
+            mut db,
+            src,
+            site_packages,
+            custom_typeshed,
+        } = setup_resolver_test();
+
+        db.with_os_file_system();
+
+        let temp_dir = tempfile::tempdir()?;
+        let root = FileSystemPath::from_std_path(temp_dir.path()).unwrap();
+
+        let src = root.join(src);
+        let site_packages = root.join(site_packages);
+        let custom_typeshed = root.join(custom_typeshed);
+
+        let foo = src.join("foo.py");
+        let bar = src.join("bar.py");
+
+        std::fs::create_dir_all(src.as_std_path())?;
+        std::fs::create_dir_all(site_packages.as_std_path())?;
+        std::fs::create_dir_all(custom_typeshed.as_std_path())?;
+
+        std::fs::write(foo.as_std_path(), "")?;
+        std::os::unix::fs::symlink(foo.as_std_path(), bar.as_std_path())?;
+
+        let settings = RawModuleResolutionSettings {
+            target_version: TargetVersion::Py38,
+            extra_paths: vec![],
+            workspace_root: src.clone(),
+            site_packages: Some(site_packages.clone()),
+            custom_typeshed: Some(custom_typeshed.clone()),
+        };
+
+        set_module_resolution_settings(&mut db, settings);
+
+        let foo_module = resolve_module(&db, ModuleName::new_static("foo").unwrap()).unwrap();
+        let bar_module = resolve_module(&db, ModuleName::new_static("bar").unwrap()).unwrap();
+
+        assert_ne!(foo_module, bar_module);
+
+        assert_eq!(&src, &foo_module.search_path());
+        assert_eq!(&foo, foo_module.file().path(&db));
+
+        // `foo` and `bar` shouldn't resolve to the same file
+
+        assert_eq!(&src, &bar_module.search_path());
+        assert_eq!(&bar, bar_module.file().path(&db));
+        assert_eq!(&foo, foo_module.file().path(&db));
+
+        assert_ne!(&foo_module, &bar_module);
+
+        assert_eq!(
+            Some(foo_module),
+            path_to_module(&db, &VfsPath::FileSystem(foo))
+        );
+        assert_eq!(
+            Some(bar_module),
+            path_to_module(&db, &VfsPath::FileSystem(bar))
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn deleting_an_unrelated_file_doesnt_change_module_resolution() -> anyhow::Result<()> {
+        let TestCase { mut db, src, .. } = setup_resolver_test();
+
+        let foo_path = src.join("foo.py");
+        let bar_path = src.join("bar.py");
+
+        db.memory_file_system()
+            .write_files([(&foo_path, "x = 1"), (&bar_path, "y = 2")])?;
+
+        let foo_module_name = ModuleName::new_static("foo").unwrap();
+        let foo_module = resolve_module(&db, foo_module_name.clone()).unwrap();
+
+        let bar = system_path_to_file(&db, &bar_path).expect("bar.py to exist");
+
+        db.clear_salsa_events();
+
+        // Delete `bar.py`
+        db.memory_file_system().remove_file(&bar_path)?;
+        bar.touch(&mut db);
+
+        // Re-query the foo module. The foo module should still be cached because `bar.py` isn't relevant
+        // for resolving `foo`.
+
+        let foo_module2 = resolve_module(&db, foo_module_name);
+
+        assert!(!db
+            .take_salsa_events()
+            .iter()
+            .any(|event| { matches!(event.kind, salsa::EventKind::WillExecute { .. }) }));
+
+        assert_eq!(Some(foo_module), foo_module2);
+
+        Ok(())
+    }
+
+    #[test]
+    fn adding_a_file_on_which_the_module_resolution_depends_on_invalidates_the_query(
+    ) -> anyhow::Result<()> {
+        let TestCase { mut db, src, .. } = setup_resolver_test();
+        let foo_path = src.join("foo.py");
+
+        let foo_module_name = ModuleName::new_static("foo").unwrap();
+        assert_eq!(resolve_module(&db, foo_module_name.clone()), None);
+
+        // Now write the foo file
+        db.memory_file_system().write_file(&foo_path, "x = 1")?;
+        VfsFile::touch_path(&mut db, &VfsPath::FileSystem(foo_path.clone()));
+        let foo_file = system_path_to_file(&db, &foo_path).expect("foo.py to exist");
+
+        let foo_module = resolve_module(&db, foo_module_name).expect("Foo module to resolve");
+        assert_eq!(foo_file, foo_module.file());
+
+        Ok(())
+    }
+
+    #[test]
+    fn removing_a_file_that_the_module_resolution_depends_on_invalidates_the_query(
+    ) -> anyhow::Result<()> {
+        let TestCase { mut db, src, .. } = setup_resolver_test();
+        let foo_path = src.join("foo.py");
+        let foo_init_path = src.join("foo/__init__.py");
+
+        db.memory_file_system()
+            .write_files([(&foo_path, "x = 1"), (&foo_init_path, "x = 2")])?;
+
+        let foo_module_name = ModuleName::new_static("foo").unwrap();
+        let foo_module = resolve_module(&db, foo_module_name.clone()).expect("foo module to exist");
+
+        assert_eq!(&foo_init_path, foo_module.file().path(&db));
+
+        // Delete `foo/__init__.py` and the `foo` folder. `foo` should now resolve to `foo.py`
+        db.memory_file_system().remove_file(&foo_init_path)?;
+        db.memory_file_system()
+            .remove_directory(foo_init_path.parent().unwrap())?;
+        VfsFile::touch_path(&mut db, &VfsPath::FileSystem(foo_init_path));
+
+        let foo_module = resolve_module(&db, foo_module_name).expect("Foo module to resolve");
+        assert_eq!(&foo_path, foo_module.file().path(&db));
+
+        Ok(())
+    }
+}

crates/red_knot_module_resolver/src/state.rs

@@ -0,0 +1,25 @@
+use ruff_db::file_system::FileSystem;
+
+use crate::db::Db;
+use crate::supported_py_version::TargetVersion;
+use crate::typeshed::LazyTypeshedVersions;
+
+pub(crate) struct ResolverState<'db> {
+    pub(crate) db: &'db dyn Db,
+    pub(crate) typeshed_versions: LazyTypeshedVersions<'db>,
+    pub(crate) target_version: TargetVersion,
+}
+
+impl<'db> ResolverState<'db> {
+    pub(crate) fn new(db: &'db dyn Db, target_version: TargetVersion) -> Self {
+        Self {
+            db,
+            typeshed_versions: LazyTypeshedVersions::new(),
+            target_version,
+        }
+    }
+
+    pub(crate) fn file_system(&self) -> &dyn FileSystem {
+        self.db.file_system()
+    }
+}

crates/red_knot_module_resolver/src/supported_py_version.rs

@@ -0,0 +1,14 @@
+/// Enumeration of all supported Python versions
+///
+/// TODO: unify with the `PythonVersion` enum in the linter/formatter crates?
+#[derive(Copy, Clone, Hash, Debug, PartialEq, Eq, PartialOrd, Ord, Default)]
+pub enum TargetVersion {
+    Py37,
+    #[default]
+    Py38,
+    Py39,
+    Py310,
+    Py311,
+    Py312,
+    Py313,
+}

crates/red_knot_module_resolver/src/typeshed.rs

@@ -1,24 +1,22 @@
-use ruff_db::vendored::VendoredFileSystem;
-use std::sync::LazyLock;
+mod versions;
 
-// The file path here is hardcoded in this crate's `build.rs` script.
-// Luckily this crate will fail to build if this file isn't available at build time.
-static TYPESHED_ZIP_BYTES: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/zipped_typeshed.zip"));
-
-pub fn file_system() -> &'static VendoredFileSystem {
-    static VENDORED_TYPESHED_STUBS: LazyLock<VendoredFileSystem> =
-        LazyLock::new(|| VendoredFileSystem::new_static(TYPESHED_ZIP_BYTES).unwrap());
-    &VENDORED_TYPESHED_STUBS
-}
+pub(crate) use versions::{
+    parse_typeshed_versions, LazyTypeshedVersions, TypeshedVersionsQueryResult,
+};
+pub use versions::{TypeshedVersionsParseError, TypeshedVersionsParseErrorKind};
 
 #[cfg(test)]
 mod tests {
     use std::io::{self, Read};
     use std::path::Path;
 
-    use ruff_db::vendored::VendoredPath;
+    use ruff_db::vendored::VendoredFileSystem;
+    use ruff_db::vfs::VendoredPath;
 
-    use super::*;
+    // The file path here is hardcoded in this crate's `build.rs` script.
+    // Luckily this crate will fail to build if this file isn't available at build time.
+    const TYPESHED_ZIP_BYTES: &[u8] =
+        include_bytes!(concat!(env!("OUT_DIR"), "/zipped_typeshed.zip"));
 
     #[test]
     fn typeshed_zip_created_at_build_time() {
@@ -41,7 +39,7 @@ mod tests {
     #[test]
     fn typeshed_vfs_consistent_with_vendored_stubs() {
         let vendored_typeshed_dir = Path::new("vendor/typeshed").canonicalize().unwrap();
-        let vendored_typeshed_stubs = file_system();
+        let vendored_typeshed_stubs = VendoredFileSystem::new(TYPESHED_ZIP_BYTES).unwrap();
 
         let mut empty_iterator = true;
         for entry in walkdir::WalkDir::new(&vendored_typeshed_dir).min_depth(1) {
@@ -71,7 +69,7 @@ mod tests {
 
             let vendored_path_kind = vendored_typeshed_stubs
                 .metadata(vendored_path)
-                .unwrap_or_else(|_| {
+                .unwrap_or_else(|| {
                     panic!(
                         "Expected metadata for {vendored_path:?} to be retrievable from the `VendoredFileSystem!
 

crates/red_knot_module_resolver/src/typeshed/versions.rs

@@ -1,30 +1,77 @@
+use std::cell::OnceCell;
 use std::collections::BTreeMap;
 use std::fmt;
 use std::num::{NonZeroU16, NonZeroUsize};
 use std::ops::{RangeFrom, RangeInclusive};
 use std::str::FromStr;
 
+use ruff_db::file_system::FileSystemPath;
+use ruff_db::source::source_text;
+use ruff_db::vfs::{system_path_to_file, VfsFile};
 use rustc_hash::FxHashMap;
 
 use crate::db::Db;
 use crate::module_name::ModuleName;
-use crate::{Program, PythonVersion};
+use crate::supported_py_version::TargetVersion;
 
-pub(in crate::module_resolver) fn vendored_typeshed_versions(db: &dyn Db) -> TypeshedVersions {
-    TypeshedVersions::from_str(
-        &db.vendored()
-            .read_to_string("stdlib/VERSIONS")
-            .expect("The vendored typeshed stubs should contain a VERSIONS file"),
-    )
-    .expect("The VERSIONS file in the vendored typeshed stubs should be well-formed")
+#[derive(Debug)]
+pub(crate) struct LazyTypeshedVersions<'db>(OnceCell<&'db TypeshedVersions>);
+
+impl<'db> LazyTypeshedVersions<'db> {
+    #[must_use]
+    pub(crate) fn new() -> Self {
+        Self(OnceCell::new())
+    }
+
+    /// Query whether a module exists at runtime in the stdlib on a certain Python version.
+    ///
+    /// Simply probing whether a file exists in typeshed is insufficient for this question,
+    /// as a module in the stdlib may have been added in Python 3.10, but the typeshed stub
+    /// will still be available (either in a custom typeshed dir or in our vendored copy)
+    /// even if the user specified Python 3.8 as the target version.
+    ///
+    /// For top-level modules and packages, the VERSIONS file can always provide an unambiguous answer
+    /// as to whether the module exists on the specified target version. However, VERSIONS does not
+    /// provide comprehensive information on all submodules, meaning that this method sometimes
+    /// returns [`TypeshedVersionsQueryResult::MaybeExists`].
+    /// See [`TypeshedVersionsQueryResult`] for more details.
+    #[must_use]
+    pub(crate) fn query_module(
+        &self,
+        module: &ModuleName,
+        db: &'db dyn Db,
+        stdlib_root: &FileSystemPath,
+        target_version: TargetVersion,
+    ) -> TypeshedVersionsQueryResult {
+        let versions = self.0.get_or_init(|| {
+            let versions_path = stdlib_root.join("VERSIONS");
+            let Some(versions_file) = system_path_to_file(db.upcast(), &versions_path) else {
+                todo!(
+                    "Still need to figure out how to handle VERSIONS files being deleted \
+                    from custom typeshed directories! Expected a file to exist at {versions_path}"
+                )
+            };
+            // TODO(Alex/Micha): If VERSIONS is invalid,
+            // this should invalidate not just the specific module resolution we're currently attempting,
+            // but all type inference that depends on any standard-library types.
+            // Unwrapping here is not correct...
+            parse_typeshed_versions(db, versions_file).as_ref().unwrap()
+        });
+        versions.query_module(module, PyVersion::from(target_version))
+    }
 }
 
-pub(crate) fn typeshed_versions(db: &dyn Db) -> &TypeshedVersions {
-    Program::get(db).search_paths(db).typeshed_versions()
+#[salsa::tracked(return_ref)]
+pub(crate) fn parse_typeshed_versions(
+    db: &dyn Db,
+    versions_file: VfsFile,
+) -> Result<TypeshedVersions, TypeshedVersionsParseError> {
+    let file_content = source_text(db.upcast(), versions_file);
+    file_content.parse()
 }
 
 #[derive(Debug, PartialEq, Eq, Clone)]
-pub(crate) struct TypeshedVersionsParseError {
+pub struct TypeshedVersionsParseError {
     line_number: Option<NonZeroU16>,
     reason: TypeshedVersionsParseErrorKind,
 }
@@ -57,7 +104,7 @@ impl std::error::Error for TypeshedVersionsParseError {
 }
 
 #[derive(Debug, PartialEq, Eq, Clone)]
-pub(super) enum TypeshedVersionsParseErrorKind {
+pub enum TypeshedVersionsParseErrorKind {
     TooManyLines(NonZeroUsize),
     UnexpectedNumberOfColons,
     InvalidModuleName(String),
@@ -67,6 +114,7 @@ pub(super) enum TypeshedVersionsParseErrorKind {
         version: String,
         err: std::num::ParseIntError,
     },
+    EmptyVersionsFile,
 }
 
 impl fmt::Display for TypeshedVersionsParseErrorKind {
@@ -95,6 +143,7 @@ impl fmt::Display for TypeshedVersionsParseErrorKind {
                 f,
                 "Failed to convert '{version}' to a pair of integers due to {err}",
             ),
+            Self::EmptyVersionsFile => f.write_str("Versions file was empty!"),
         }
     }
 }
@@ -109,13 +158,13 @@ impl TypeshedVersions {
     }
 
     #[must_use]
-    pub(in crate::module_resolver) fn query_module(
+    fn query_module(
         &self,
         module: &ModuleName,
-        python_version: PythonVersion,
+        target_version: PyVersion,
     ) -> TypeshedVersionsQueryResult {
         if let Some(range) = self.exact(module) {
-            if range.contains(python_version) {
+            if range.contains(target_version) {
                 TypeshedVersionsQueryResult::Exists
             } else {
                 TypeshedVersionsQueryResult::DoesNotExist
@@ -125,7 +174,7 @@ impl TypeshedVersions {
             while let Some(module_to_try) = module {
                 if let Some(range) = self.exact(&module_to_try) {
                     return {
-                        if range.contains(python_version) {
+                        if range.contains(target_version) {
                             TypeshedVersionsQueryResult::MaybeExists
                         } else {
                             TypeshedVersionsQueryResult::DoesNotExist
@@ -139,7 +188,7 @@ impl TypeshedVersions {
     }
 }
 
-/// Possible answers [`TypeshedVersions::query_module()`] could give to the question:
+/// Possible answers [`LazyTypeshedVersions::query_module()`] could give to the question:
 /// "Does this module exist in the stdlib at runtime on a certain target version?"
 #[derive(Debug, Copy, PartialEq, Eq, Clone, Hash)]
 pub(crate) enum TypeshedVersionsQueryResult {
@@ -241,7 +290,14 @@ impl FromStr for TypeshedVersions {
             };
         }
 
-        Ok(Self(map))
+        if map.is_empty() {
+            Err(TypeshedVersionsParseError {
+                line_number: None,
+                reason: TypeshedVersionsParseErrorKind::EmptyVersionsFile,
+            })
+        } else {
+            Ok(Self(map))
+        }
     }
 }
 
@@ -257,13 +313,13 @@ impl fmt::Display for TypeshedVersions {
 
 #[derive(Debug, Clone, Eq, PartialEq, Hash)]
 enum PyVersionRange {
-    AvailableFrom(RangeFrom<PythonVersion>),
-    AvailableWithin(RangeInclusive<PythonVersion>),
+    AvailableFrom(RangeFrom<PyVersion>),
+    AvailableWithin(RangeInclusive<PyVersion>),
 }
 
 impl PyVersionRange {
     #[must_use]
-    fn contains(&self, version: PythonVersion) -> bool {
+    fn contains(&self, version: PyVersion) -> bool {
         match self {
             Self::AvailableFrom(inner) => inner.contains(&version),
             Self::AvailableWithin(inner) => inner.contains(&version),
@@ -277,14 +333,9 @@ impl FromStr for PyVersionRange {
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         let mut parts = s.split('-').map(str::trim);
         match (parts.next(), parts.next(), parts.next()) {
-            (Some(lower), Some(""), None) => {
-                let lower = PythonVersion::from_versions_file_string(lower)?;
-                Ok(Self::AvailableFrom(lower..))
-            }
+            (Some(lower), Some(""), None) => Ok(Self::AvailableFrom((lower.parse()?)..)),
             (Some(lower), Some(upper), None) => {
-                let lower = PythonVersion::from_versions_file_string(lower)?;
-                let upper = PythonVersion::from_versions_file_string(upper)?;
-                Ok(Self::AvailableWithin(lower..=upper))
+                Ok(Self::AvailableWithin((lower.parse()?)..=(upper.parse()?)))
             }
             _ => Err(TypeshedVersionsParseErrorKind::UnexpectedNumberOfHyphens),
         }
@@ -302,20 +353,74 @@ impl fmt::Display for PyVersionRange {
     }
 }
 
-impl PythonVersion {
-    fn from_versions_file_string(s: &str) -> Result<Self, TypeshedVersionsParseErrorKind> {
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
+struct PyVersion {
+    major: u8,
+    minor: u8,
+}
+
+impl FromStr for PyVersion {
+    type Err = TypeshedVersionsParseErrorKind;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
         let mut parts = s.split('.').map(str::trim);
         let (Some(major), Some(minor), None) = (parts.next(), parts.next(), parts.next()) else {
             return Err(TypeshedVersionsParseErrorKind::UnexpectedNumberOfPeriods(
                 s.to_string(),
             ));
         };
-        PythonVersion::try_from((major, minor)).map_err(|int_parse_error| {
-            TypeshedVersionsParseErrorKind::IntegerParsingFailure {
-                version: s.to_string(),
-                err: int_parse_error,
+        let major = match u8::from_str(major) {
+            Ok(major) => major,
+            Err(err) => {
+                return Err(TypeshedVersionsParseErrorKind::IntegerParsingFailure {
+                    version: s.to_string(),
+                    err,
+                })
             }
-        })
+        };
+        let minor = match u8::from_str(minor) {
+            Ok(minor) => minor,
+            Err(err) => {
+                return Err(TypeshedVersionsParseErrorKind::IntegerParsingFailure {
+                    version: s.to_string(),
+                    err,
+                })
+            }
+        };
+        Ok(Self { major, minor })
+    }
+}
+
+impl fmt::Display for PyVersion {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let PyVersion { major, minor } = self;
+        write!(f, "{major}.{minor}")
+    }
+}
+
+impl From<TargetVersion> for PyVersion {
+    fn from(value: TargetVersion) -> Self {
+        match value {
+            TargetVersion::Py37 => PyVersion { major: 3, minor: 7 },
+            TargetVersion::Py38 => PyVersion { major: 3, minor: 8 },
+            TargetVersion::Py39 => PyVersion { major: 3, minor: 9 },
+            TargetVersion::Py310 => PyVersion {
+                major: 3,
+                minor: 10,
+            },
+            TargetVersion::Py311 => PyVersion {
+                major: 3,
+                minor: 11,
+            },
+            TargetVersion::Py312 => PyVersion {
+                major: 3,
+                minor: 12,
+            },
+            TargetVersion::Py313 => PyVersion {
+                major: 3,
+                minor: 13,
+            },
+        }
     }
 }
 
@@ -324,12 +429,10 @@ mod tests {
     use std::num::{IntErrorKind, NonZeroU16};
     use std::path::Path;
 
-    use insta::assert_snapshot;
-
-    use crate::db::tests::TestDb;
-
     use super::*;
 
+    use insta::assert_snapshot;
+
     const TYPESHED_STDLIB_DIR: &str = "stdlib";
 
     #[allow(unsafe_code)]
@@ -349,9 +452,12 @@ mod tests {
 
     #[test]
     fn can_parse_vendored_versions_file() {
-        let db = TestDb::new();
+        let versions_data = include_str!(concat!(
+            env!("CARGO_MANIFEST_DIR"),
+            "/vendor/typeshed/stdlib/VERSIONS"
+        ));
 
-        let versions = vendored_typeshed_versions(&db);
+        let versions = TypeshedVersions::from_str(versions_data).unwrap();
         assert!(versions.len() > 100);
         assert!(versions.len() < 1000);
 
@@ -361,37 +467,36 @@ mod tests {
 
         assert!(versions.contains_exact(&asyncio));
         assert_eq!(
-            versions.query_module(&asyncio, PythonVersion::PY310),
+            versions.query_module(&asyncio, TargetVersion::Py310.into()),
             TypeshedVersionsQueryResult::Exists
         );
 
         assert!(versions.contains_exact(&asyncio_staggered));
         assert_eq!(
-            versions.query_module(&asyncio_staggered, PythonVersion::PY38),
+            versions.query_module(&asyncio_staggered, TargetVersion::Py38.into()),
             TypeshedVersionsQueryResult::Exists
         );
         assert_eq!(
-            versions.query_module(&asyncio_staggered, PythonVersion::PY37),
+            versions.query_module(&asyncio_staggered, TargetVersion::Py37.into()),
             TypeshedVersionsQueryResult::DoesNotExist
         );
 
         assert!(versions.contains_exact(&audioop));
         assert_eq!(
-            versions.query_module(&audioop, PythonVersion::PY312),
+            versions.query_module(&audioop, TargetVersion::Py312.into()),
             TypeshedVersionsQueryResult::Exists
         );
         assert_eq!(
-            versions.query_module(&audioop, PythonVersion::PY313),
+            versions.query_module(&audioop, TargetVersion::Py313.into()),
             TypeshedVersionsQueryResult::DoesNotExist
         );
     }
 
     #[test]
     fn typeshed_versions_consistent_with_vendored_stubs() {
-        let db = TestDb::new();
-        let vendored_typeshed_versions = vendored_typeshed_versions(&db);
-        let vendored_typeshed_dir =
-            Path::new(env!("CARGO_MANIFEST_DIR")).join("../red_knot_vendored/vendor/typeshed");
+        const VERSIONS_DATA: &str = include_str!("../../vendor/typeshed/stdlib/VERSIONS");
+        let vendored_typeshed_dir = Path::new("vendor/typeshed").canonicalize().unwrap();
+        let vendored_typeshed_versions = TypeshedVersions::from_str(VERSIONS_DATA).unwrap();
 
         let mut empty_iterator = true;
 
@@ -459,11 +564,11 @@ foo: 3.8-   # trailing comment
 ";
         let parsed_versions = TypeshedVersions::from_str(VERSIONS).unwrap();
         assert_eq!(parsed_versions.len(), 3);
-        assert_snapshot!(parsed_versions.to_string(), @r"
+        assert_snapshot!(parsed_versions.to_string(), @r###"
         bar: 2.7-3.10
         bar.baz: 3.1-3.9
         foo: 3.8-
-        "
+        "###
         );
     }
 
@@ -474,15 +579,15 @@ foo: 3.8-   # trailing comment
 
         assert!(parsed_versions.contains_exact(&bar));
         assert_eq!(
-            parsed_versions.query_module(&bar, PythonVersion::PY37),
+            parsed_versions.query_module(&bar, TargetVersion::Py37.into()),
             TypeshedVersionsQueryResult::Exists
         );
         assert_eq!(
-            parsed_versions.query_module(&bar, PythonVersion::PY310),
+            parsed_versions.query_module(&bar, TargetVersion::Py310.into()),
             TypeshedVersionsQueryResult::Exists
         );
         assert_eq!(
-            parsed_versions.query_module(&bar, PythonVersion::PY311),
+            parsed_versions.query_module(&bar, TargetVersion::Py311.into()),
             TypeshedVersionsQueryResult::DoesNotExist
         );
     }
@@ -494,15 +599,15 @@ foo: 3.8-   # trailing comment
 
         assert!(parsed_versions.contains_exact(&foo));
         assert_eq!(
-            parsed_versions.query_module(&foo, PythonVersion::PY37),
+            parsed_versions.query_module(&foo, TargetVersion::Py37.into()),
             TypeshedVersionsQueryResult::DoesNotExist
         );
         assert_eq!(
-            parsed_versions.query_module(&foo, PythonVersion::PY38),
+            parsed_versions.query_module(&foo, TargetVersion::Py38.into()),
             TypeshedVersionsQueryResult::Exists
         );
         assert_eq!(
-            parsed_versions.query_module(&foo, PythonVersion::PY311),
+            parsed_versions.query_module(&foo, TargetVersion::Py311.into()),
             TypeshedVersionsQueryResult::Exists
         );
     }
@@ -514,15 +619,15 @@ foo: 3.8-   # trailing comment
 
         assert!(parsed_versions.contains_exact(&bar_baz));
         assert_eq!(
-            parsed_versions.query_module(&bar_baz, PythonVersion::PY37),
+            parsed_versions.query_module(&bar_baz, TargetVersion::Py37.into()),
             TypeshedVersionsQueryResult::Exists
         );
         assert_eq!(
-            parsed_versions.query_module(&bar_baz, PythonVersion::PY39),
+            parsed_versions.query_module(&bar_baz, TargetVersion::Py39.into()),
             TypeshedVersionsQueryResult::Exists
         );
         assert_eq!(
-            parsed_versions.query_module(&bar_baz, PythonVersion::PY310),
+            parsed_versions.query_module(&bar_baz, TargetVersion::Py310.into()),
             TypeshedVersionsQueryResult::DoesNotExist
         );
     }
@@ -534,15 +639,15 @@ foo: 3.8-   # trailing comment
 
         assert!(!parsed_versions.contains_exact(&bar_eggs));
         assert_eq!(
-            parsed_versions.query_module(&bar_eggs, PythonVersion::PY37),
+            parsed_versions.query_module(&bar_eggs, TargetVersion::Py37.into()),
             TypeshedVersionsQueryResult::MaybeExists
         );
         assert_eq!(
-            parsed_versions.query_module(&bar_eggs, PythonVersion::PY310),
+            parsed_versions.query_module(&bar_eggs, TargetVersion::Py310.into()),
             TypeshedVersionsQueryResult::MaybeExists
         );
         assert_eq!(
-            parsed_versions.query_module(&bar_eggs, PythonVersion::PY311),
+            parsed_versions.query_module(&bar_eggs, TargetVersion::Py311.into()),
             TypeshedVersionsQueryResult::DoesNotExist
         );
     }
@@ -554,15 +659,40 @@ foo: 3.8-   # trailing comment
 
         assert!(!parsed_versions.contains_exact(&spam));
         assert_eq!(
-            parsed_versions.query_module(&spam, PythonVersion::PY37),
+            parsed_versions.query_module(&spam, TargetVersion::Py37.into()),
             TypeshedVersionsQueryResult::DoesNotExist
         );
         assert_eq!(
-            parsed_versions.query_module(&spam, PythonVersion::PY313),
+            parsed_versions.query_module(&spam, TargetVersion::Py313.into()),
             TypeshedVersionsQueryResult::DoesNotExist
         );
     }
 
+    #[test]
+    fn invalid_empty_versions_file() {
+        assert_eq!(
+            TypeshedVersions::from_str(""),
+            Err(TypeshedVersionsParseError {
+                line_number: None,
+                reason: TypeshedVersionsParseErrorKind::EmptyVersionsFile
+            })
+        );
+        assert_eq!(
+            TypeshedVersions::from_str("       "),
+            Err(TypeshedVersionsParseError {
+                line_number: None,
+                reason: TypeshedVersionsParseErrorKind::EmptyVersionsFile
+            })
+        );
+        assert_eq!(
+            TypeshedVersions::from_str(" \n  \n  \n "),
+            Err(TypeshedVersionsParseError {
+                line_number: None,
+                reason: TypeshedVersionsParseErrorKind::EmptyVersionsFile
+            })
+        );
+    }
+
     #[test]
     fn invalid_huge_versions_file() {
         let offset = 100;

crates/red_knot_module_resolver/vendor/typeshed/README.md

@@ -21,7 +21,7 @@ the project the stubs are for, but instead report them here to typeshed.**
 Further documentation on stub files, typeshed, and Python's typing system in
 general, can also be found at https://typing.readthedocs.io/en/latest/.
 
-Typeshed supports Python versions 3.9 to 3.13.
+Typeshed supports Python versions 3.8 and up.
 
 ## Using
 

crates/red_knot_module_resolver/vendor/typeshed/source_commit.txt

@@ -0,0 +1 @@
+dcab6e88883c629ede9637fb011958f8b4918f52

crates/red_knot_module_resolver/vendor/typeshed/stdlib/VERSIONS

@@ -20,55 +20,35 @@
 __future__: 3.0-
 __main__: 3.0-
 _ast: 3.0-
-_asyncio: 3.0-
 _bisect: 3.0-
-_blake2: 3.6-
 _bootlocale: 3.4-3.9
-_bz2: 3.3-
 _codecs: 3.0-
 _collections_abc: 3.3-
 _compat_pickle: 3.1-
 _compression: 3.5-
-_contextvars: 3.7-
 _csv: 3.0-
 _ctypes: 3.0-
 _curses: 3.0-
-_curses_panel: 3.0-
-_dbm: 3.0-
 _decimal: 3.3-
 _dummy_thread: 3.0-3.8
 _dummy_threading: 3.0-3.8
-_frozen_importlib: 3.0-
-_frozen_importlib_external: 3.5-
-_gdbm: 3.0-
-_hashlib: 3.0-
 _heapq: 3.0-
 _imp: 3.0-
 _interpchannels: 3.13-
-_interpqueues: 3.13-
-_interpreters: 3.13-
-_io: 3.0-
 _json: 3.0-
 _locale: 3.0-
 _lsprof: 3.0-
-_lzma: 3.3-
 _markupbase: 3.0-
-_msi: 3.0-3.12
-_multibytecodec: 3.0-
+_msi: 3.0-
 _operator: 3.4-
 _osx_support: 3.0-
-_pickle: 3.0-
 _posixsubprocess: 3.2-
 _py_abc: 3.7-
 _pydecimal: 3.5-
-_queue: 3.7-
 _random: 3.0-
 _sitebuiltins: 3.4-
 _socket: 3.0-  # present in 3.0 at runtime, but not in typeshed
-_sqlite3: 3.0-
-_ssl: 3.0-
 _stat: 3.4-
-_struct: 3.0-
 _thread: 3.0-
 _threading_local: 3.0-
 _tkinter: 3.0-
@@ -132,7 +112,6 @@ curses: 3.0-
 dataclasses: 3.7-
 datetime: 3.0-
 dbm: 3.0-
-dbm.sqlite3: 3.13-
 decimal: 3.0-
 difflib: 3.0-
 dis: 3.0-
@@ -143,12 +122,6 @@ doctest: 3.0-
 dummy_threading: 3.0-3.8
 email: 3.0-
 encodings: 3.0-
-encodings.cp1125: 3.4-
-encodings.cp273: 3.4-
-encodings.cp858: 3.2-
-encodings.koi8_t: 3.5-
-encodings.kz1048: 3.5-
-encodings.mac_centeuro: 3.0-3.8
 ensurepip: 3.0-
 enum: 3.4-
 errno: 3.0-
@@ -180,15 +153,10 @@ imghdr: 3.0-3.12
 imp: 3.0-3.11
 importlib: 3.0-
 importlib._abc: 3.10-
-importlib._bootstrap: 3.0-
-importlib._bootstrap_external: 3.5-
 importlib.metadata: 3.8-
 importlib.metadata._meta: 3.10-
-importlib.metadata.diagnose: 3.13-
 importlib.readers: 3.10-
 importlib.resources: 3.7-
-importlib.resources._common: 3.11-
-importlib.resources._functional: 3.13-
 importlib.resources.abc: 3.11-
 importlib.resources.readers: 3.11-
 importlib.resources.simple: 3.11-

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_codecs.pyi

@@ -2,13 +2,10 @@ import codecs
 import sys
 from _typeshed import ReadableBuffer
 from collections.abc import Callable
-from typing import Literal, final, overload, type_check_only
+from typing import Literal, overload
 from typing_extensions import TypeAlias
 
 # This type is not exposed; it is defined in unicodeobject.c
-# At runtime it calls itself builtins.EncodingMap
-@final
-@type_check_only
 class _EncodingMap:
     def size(self) -> int: ...
 

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_collections_abc.pyi

@@ -1,14 +1,14 @@
 import sys
 from abc import abstractmethod
 from types import MappingProxyType
-from typing import (  # noqa: Y022,Y038
+from typing import (  # noqa: Y022,Y038,Y057
     AbstractSet as Set,
     AsyncGenerator as AsyncGenerator,
     AsyncIterable as AsyncIterable,
     AsyncIterator as AsyncIterator,
     Awaitable as Awaitable,
+    ByteString as ByteString,
     Callable as Callable,
-    ClassVar,
     Collection as Collection,
     Container as Container,
     Coroutine as Coroutine,
@@ -59,12 +59,8 @@ __all__ = [
     "ValuesView",
     "Sequence",
     "MutableSequence",
+    "ByteString",
 ]
-if sys.version_info < (3, 14):
-    from typing import ByteString as ByteString  # noqa: Y057
-
-    __all__ += ["ByteString"]
-
 if sys.version_info >= (3, 12):
     __all__ += ["Buffer"]
 
@@ -74,17 +70,12 @@ _VT_co = TypeVar("_VT_co", covariant=True)  # Value type covariant containers.
 @final
 class dict_keys(KeysView[_KT_co], Generic[_KT_co, _VT_co]):  # undocumented
     def __eq__(self, value: object, /) -> bool: ...
-    def __reversed__(self) -> Iterator[_KT_co]: ...
-    __hash__: ClassVar[None]  # type: ignore[assignment]
-    if sys.version_info >= (3, 13):
-        def isdisjoint(self, other: Iterable[_KT_co], /) -> bool: ...
     if sys.version_info >= (3, 10):
         @property
         def mapping(self) -> MappingProxyType[_KT_co, _VT_co]: ...
 
 @final
 class dict_values(ValuesView[_VT_co], Generic[_KT_co, _VT_co]):  # undocumented
-    def __reversed__(self) -> Iterator[_VT_co]: ...
     if sys.version_info >= (3, 10):
         @property
         def mapping(self) -> MappingProxyType[_KT_co, _VT_co]: ...
@@ -92,10 +83,6 @@ class dict_values(ValuesView[_VT_co], Generic[_KT_co, _VT_co]):  # undocumented
 @final
 class dict_items(ItemsView[_KT_co, _VT_co]):  # undocumented
     def __eq__(self, value: object, /) -> bool: ...
-    def __reversed__(self) -> Iterator[tuple[_KT_co, _VT_co]]: ...
-    __hash__: ClassVar[None]  # type: ignore[assignment]
-    if sys.version_info >= (3, 13):
-        def isdisjoint(self, other: Iterable[tuple[_KT_co, _VT_co]], /) -> bool: ...
     if sys.version_info >= (3, 10):
         @property
         def mapping(self) -> MappingProxyType[_KT_co, _VT_co]: ...

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_csv.pyi

@@ -0,0 +1,90 @@
+import sys
+from _typeshed import SupportsWrite
+from collections.abc import Iterable, Iterator
+from typing import Any, Final, Literal
+from typing_extensions import TypeAlias
+
+__version__: Final[str]
+
+QUOTE_ALL: Literal[1]
+QUOTE_MINIMAL: Literal[0]
+QUOTE_NONE: Literal[3]
+QUOTE_NONNUMERIC: Literal[2]
+if sys.version_info >= (3, 12):
+    QUOTE_STRINGS: Literal[4]
+    QUOTE_NOTNULL: Literal[5]
+
+# Ideally this would be `QUOTE_ALL | QUOTE_MINIMAL | QUOTE_NONE | QUOTE_NONNUMERIC`
+# However, using literals in situations like these can cause false-positives (see #7258)
+_QuotingType: TypeAlias = int
+
+class Error(Exception): ...
+
+class Dialect:
+    delimiter: str
+    quotechar: str | None
+    escapechar: str | None
+    doublequote: bool
+    skipinitialspace: bool
+    lineterminator: str
+    quoting: _QuotingType
+    strict: bool
+    def __init__(self) -> None: ...
+
+_DialectLike: TypeAlias = str | Dialect | type[Dialect]
+
+class _reader(Iterator[list[str]]):
+    @property
+    def dialect(self) -> Dialect: ...
+    line_num: int
+    def __next__(self) -> list[str]: ...
+
+class _writer:
+    @property
+    def dialect(self) -> Dialect: ...
+    def writerow(self, row: Iterable[Any]) -> Any: ...
+    def writerows(self, rows: Iterable[Iterable[Any]]) -> None: ...
+
+def writer(
+    csvfile: SupportsWrite[str],
+    dialect: _DialectLike = "excel",
+    *,
+    delimiter: str = ",",
+    quotechar: str | None = '"',
+    escapechar: str | None = None,
+    doublequote: bool = True,
+    skipinitialspace: bool = False,
+    lineterminator: str = "\r\n",
+    quoting: _QuotingType = 0,
+    strict: bool = False,
+) -> _writer: ...
+def reader(
+    csvfile: Iterable[str],
+    dialect: _DialectLike = "excel",
+    *,
+    delimiter: str = ",",
+    quotechar: str | None = '"',
+    escapechar: str | None = None,
+    doublequote: bool = True,
+    skipinitialspace: bool = False,
+    lineterminator: str = "\r\n",
+    quoting: _QuotingType = 0,
+    strict: bool = False,
+) -> _reader: ...
+def register_dialect(
+    name: str,
+    dialect: type[Dialect] = ...,
+    *,
+    delimiter: str = ",",
+    quotechar: str | None = '"',
+    escapechar: str | None = None,
+    doublequote: bool = True,
+    skipinitialspace: bool = False,
+    lineterminator: str = "\r\n",
+    quoting: _QuotingType = 0,
+    strict: bool = False,
+) -> None: ...
+def unregister_dialect(name: str) -> None: ...
+def get_dialect(name: str) -> Dialect: ...
+def list_dialects() -> list[str]: ...
+def field_size_limit(new_limit: int = ...) -> int: ...

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_ctypes.pyi

@@ -0,0 +1,211 @@
+import sys
+from _typeshed import ReadableBuffer, WriteableBuffer
+from abc import abstractmethod
+from collections.abc import Callable, Iterable, Iterator, Mapping, Sequence
+from ctypes import CDLL, ArgumentError as ArgumentError
+from typing import Any, ClassVar, Generic, TypeVar, overload
+from typing_extensions import Self, TypeAlias
+
+if sys.version_info >= (3, 9):
+    from types import GenericAlias
+
+_T = TypeVar("_T")
+_CT = TypeVar("_CT", bound=_CData)
+
+FUNCFLAG_CDECL: int
+FUNCFLAG_PYTHONAPI: int
+FUNCFLAG_USE_ERRNO: int
+FUNCFLAG_USE_LASTERROR: int
+RTLD_GLOBAL: int
+RTLD_LOCAL: int
+
+if sys.version_info >= (3, 11):
+    CTYPES_MAX_ARGCOUNT: int
+
+if sys.version_info >= (3, 12):
+    SIZEOF_TIME_T: int
+
+if sys.platform == "win32":
+    # Description, Source, HelpFile, HelpContext, scode
+    _COMError_Details: TypeAlias = tuple[str | None, str | None, str | None, int | None, int | None]
+
+    class COMError(Exception):
+        hresult: int
+        text: str | None
+        details: _COMError_Details
+
+        def __init__(self, hresult: int, text: str | None, details: _COMError_Details) -> None: ...
+
+    def CopyComPointer(src: _PointerLike, dst: _PointerLike | _CArgObject) -> int: ...
+
+    FUNCFLAG_HRESULT: int
+    FUNCFLAG_STDCALL: int
+
+    def FormatError(code: int = ...) -> str: ...
+    def get_last_error() -> int: ...
+    def set_last_error(value: int) -> int: ...
+    def LoadLibrary(name: str, load_flags: int = 0, /) -> int: ...
+    def FreeLibrary(handle: int, /) -> None: ...
+
+class _CDataMeta(type):
+    # By default mypy complains about the following two methods, because strictly speaking cls
+    # might not be a Type[_CT]. However this can never actually happen, because the only class that
+    # uses _CDataMeta as its metaclass is _CData. So it's safe to ignore the errors here.
+    def __mul__(cls: type[_CT], other: int) -> type[Array[_CT]]: ...  # type: ignore[misc]
+    def __rmul__(cls: type[_CT], other: int) -> type[Array[_CT]]: ...  # type: ignore[misc]
+
+class _CData(metaclass=_CDataMeta):
+    _b_base_: int
+    _b_needsfree_: bool
+    _objects: Mapping[Any, int] | None
+    # At runtime the following classmethods are available only on classes, not
+    # on instances. This can't be reflected properly in the type system:
+    #
+    # Structure.from_buffer(...)  # valid at runtime
+    # Structure(...).from_buffer(...)  # invalid at runtime
+    #
+
+    @classmethod
+    def from_buffer(cls, source: WriteableBuffer, offset: int = ...) -> Self: ...
+    @classmethod
+    def from_buffer_copy(cls, source: ReadableBuffer, offset: int = ...) -> Self: ...
+    @classmethod
+    def from_address(cls, address: int) -> Self: ...
+    @classmethod
+    def from_param(cls, obj: Any) -> Self | _CArgObject: ...
+    @classmethod
+    def in_dll(cls, library: CDLL, name: str) -> Self: ...
+    def __buffer__(self, flags: int, /) -> memoryview: ...
+    def __release_buffer__(self, buffer: memoryview, /) -> None: ...
+
+class _SimpleCData(_CData, Generic[_T]):
+    value: _T
+    # The TypeVar can be unsolved here,
+    # but we can't use overloads without creating many, many mypy false-positive errors
+    def __init__(self, value: _T = ...) -> None: ...  # pyright: ignore[reportInvalidTypeVarUse]
+
+class _CanCastTo(_CData): ...
+class _PointerLike(_CanCastTo): ...
+
+class _Pointer(_PointerLike, _CData, Generic[_CT]):
+    _type_: type[_CT]
+    contents: _CT
+    @overload
+    def __init__(self) -> None: ...
+    @overload
+    def __init__(self, arg: _CT) -> None: ...
+    @overload
+    def __getitem__(self, key: int, /) -> Any: ...
+    @overload
+    def __getitem__(self, key: slice, /) -> list[Any]: ...
+    def __setitem__(self, key: int, value: Any, /) -> None: ...
+
+def POINTER(type: type[_CT]) -> type[_Pointer[_CT]]: ...
+def pointer(arg: _CT, /) -> _Pointer[_CT]: ...
+
+class _CArgObject: ...
+
+def byref(obj: _CData, offset: int = ...) -> _CArgObject: ...
+
+_ECT: TypeAlias = Callable[[_CData | None, CFuncPtr, tuple[_CData, ...]], _CData]
+_PF: TypeAlias = tuple[int] | tuple[int, str | None] | tuple[int, str | None, Any]
+
+class CFuncPtr(_PointerLike, _CData):
+    restype: type[_CData] | Callable[[int], Any] | None
+    argtypes: Sequence[type[_CData]]
+    errcheck: _ECT
+    # Abstract attribute that must be defined on subclasses
+    _flags_: ClassVar[int]
+    @overload
+    def __init__(self) -> None: ...
+    @overload
+    def __init__(self, address: int, /) -> None: ...
+    @overload
+    def __init__(self, callable: Callable[..., Any], /) -> None: ...
+    @overload
+    def __init__(self, func_spec: tuple[str | int, CDLL], paramflags: tuple[_PF, ...] | None = ..., /) -> None: ...
+    if sys.platform == "win32":
+        @overload
+        def __init__(
+            self, vtbl_index: int, name: str, paramflags: tuple[_PF, ...] | None = ..., iid: _CData | None = ..., /
+        ) -> None: ...
+
+    def __call__(self, *args: Any, **kwargs: Any) -> Any: ...
+
+_GetT = TypeVar("_GetT")
+_SetT = TypeVar("_SetT")
+
+class _CField(Generic[_CT, _GetT, _SetT]):
+    offset: int
+    size: int
+    @overload
+    def __get__(self, instance: None, owner: type[Any] | None, /) -> Self: ...
+    @overload
+    def __get__(self, instance: Any, owner: type[Any] | None, /) -> _GetT: ...
+    def __set__(self, instance: Any, value: _SetT, /) -> None: ...
+
+class _StructUnionMeta(_CDataMeta):
+    _fields_: Sequence[tuple[str, type[_CData]] | tuple[str, type[_CData], int]]
+    _pack_: int
+    _anonymous_: Sequence[str]
+    def __getattr__(self, name: str) -> _CField[Any, Any, Any]: ...
+
+class _StructUnionBase(_CData, metaclass=_StructUnionMeta):
+    def __init__(self, *args: Any, **kw: Any) -> None: ...
+    def __getattr__(self, name: str) -> Any: ...
+    def __setattr__(self, name: str, value: Any) -> None: ...
+
+class Union(_StructUnionBase): ...
+class Structure(_StructUnionBase): ...
+
+class Array(_CData, Generic[_CT]):
+    @property
+    @abstractmethod
+    def _length_(self) -> int: ...
+    @_length_.setter
+    def _length_(self, value: int) -> None: ...
+    @property
+    @abstractmethod
+    def _type_(self) -> type[_CT]: ...
+    @_type_.setter
+    def _type_(self, value: type[_CT]) -> None: ...
+    # Note: only available if _CT == c_char
+    @property
+    def raw(self) -> bytes: ...
+    @raw.setter
+    def raw(self, value: ReadableBuffer) -> None: ...
+    value: Any  # Note: bytes if _CT == c_char, str if _CT == c_wchar, unavailable otherwise
+    # TODO These methods cannot be annotated correctly at the moment.
+    # All of these "Any"s stand for the array's element type, but it's not possible to use _CT
+    # here, because of a special feature of ctypes.
+    # By default, when accessing an element of an Array[_CT], the returned object has type _CT.
+    # However, when _CT is a "simple type" like c_int, ctypes automatically "unboxes" the object
+    # and converts it to the corresponding Python primitive. For example, when accessing an element
+    # of an Array[c_int], a Python int object is returned, not a c_int.
+    # This behavior does *not* apply to subclasses of "simple types".
+    # If MyInt is a subclass of c_int, then accessing an element of an Array[MyInt] returns
+    # a MyInt, not an int.
+    # This special behavior is not easy to model in a stub, so for now all places where
+    # the array element type would belong are annotated with Any instead.
+    def __init__(self, *args: Any) -> None: ...
+    @overload
+    def __getitem__(self, key: int, /) -> Any: ...
+    @overload
+    def __getitem__(self, key: slice, /) -> list[Any]: ...
+    @overload
+    def __setitem__(self, key: int, value: Any, /) -> None: ...
+    @overload
+    def __setitem__(self, key: slice, value: Iterable[Any], /) -> None: ...
+    def __iter__(self) -> Iterator[Any]: ...
+    # Can't inherit from Sized because the metaclass conflict between
+    # Sized and _CData prevents using _CDataMeta.
+    def __len__(self) -> int: ...
+    if sys.version_info >= (3, 9):
+        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
+
+def addressof(obj: _CData) -> int: ...
+def alignment(obj_or_type: _CData | type[_CData]) -> int: ...
+def get_errno() -> int: ...
+def resize(obj: _CData, size: int) -> None: ...
+def set_errno(value: int) -> int: ...
+def sizeof(obj_or_type: _CData | type[_CData]) -> int: ...

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_curses.pyi

@@ -1,7 +1,6 @@
 import sys
-from _typeshed import ReadOnlyBuffer, SupportsRead, SupportsWrite
-from curses import _ncurses_version
-from typing import Any, final, overload
+from _typeshed import ReadOnlyBuffer, SupportsRead
+from typing import IO, Any, NamedTuple, final, overload
 from typing_extensions import TypeAlias
 
 # NOTE: This module is ordinarily only available on Unix, but the windows-curses
@@ -299,7 +298,7 @@ if sys.version_info >= (3, 9):
 
 def getmouse() -> tuple[int, int, int, int, int]: ...
 def getsyx() -> tuple[int, int]: ...
-def getwin(file: SupportsRead[bytes], /) -> window: ...
+def getwin(file: SupportsRead[bytes], /) -> _CursesWindow: ...
 def halfdelay(tenths: int, /) -> None: ...
 def has_colors() -> bool: ...
 
@@ -311,7 +310,7 @@ def has_il() -> bool: ...
 def has_key(key: int, /) -> bool: ...
 def init_color(color_number: int, r: int, g: int, b: int, /) -> None: ...
 def init_pair(pair_number: int, fg: int, bg: int, /) -> None: ...
-def initscr() -> window: ...
+def initscr() -> _CursesWindow: ...
 def intrflush(flag: bool, /) -> None: ...
 def is_term_resized(nlines: int, ncols: int, /) -> bool: ...
 def isendwin() -> bool: ...
@@ -322,8 +321,8 @@ def meta(yes: bool, /) -> None: ...
 def mouseinterval(interval: int, /) -> None: ...
 def mousemask(newmask: int, /) -> tuple[int, int]: ...
 def napms(ms: int, /) -> int: ...
-def newpad(nlines: int, ncols: int, /) -> window: ...
-def newwin(nlines: int, ncols: int, begin_y: int = ..., begin_x: int = ..., /) -> window: ...
+def newpad(nlines: int, ncols: int, /) -> _CursesWindow: ...
+def newwin(nlines: int, ncols: int, begin_y: int = ..., begin_x: int = ..., /) -> _CursesWindow: ...
 def nl(flag: bool = True, /) -> None: ...
 def nocbreak() -> None: ...
 def noecho() -> None: ...
@@ -369,7 +368,11 @@ def tparm(
 ) -> bytes: ...
 def typeahead(fd: int, /) -> None: ...
 def unctrl(ch: _ChType, /) -> bytes: ...
-def unget_wch(ch: int | str, /) -> None: ...
+
+if sys.version_info < (3, 12) or sys.platform != "darwin":
+    # The support for macos was dropped in 3.12
+    def unget_wch(ch: int | str, /) -> None: ...
+
 def ungetch(ch: _ChType, /) -> None: ...
 def ungetmouse(id: int, x: int, y: int, z: int, bstate: int, /) -> None: ...
 def update_lines_cols() -> None: ...
@@ -379,7 +382,7 @@ def use_env(flag: bool, /) -> None: ...
 class error(Exception): ...
 
 @final
-class window:  # undocumented
+class _CursesWindow:
     encoding: str
     @overload
     def addch(self, ch: _ChType, attr: int = ...) -> None: ...
@@ -432,9 +435,9 @@ class window:  # undocumented
     def delch(self, y: int, x: int) -> None: ...
     def deleteln(self) -> None: ...
     @overload
-    def derwin(self, begin_y: int, begin_x: int) -> window: ...
+    def derwin(self, begin_y: int, begin_x: int) -> _CursesWindow: ...
     @overload
-    def derwin(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> window: ...
+    def derwin(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> _CursesWindow: ...
     def echochar(self, ch: _ChType, attr: int = ..., /) -> None: ...
     def enclose(self, y: int, x: int, /) -> bool: ...
     def erase(self) -> None: ...
@@ -444,10 +447,13 @@ class window:  # undocumented
     def getch(self) -> int: ...
     @overload
     def getch(self, y: int, x: int) -> int: ...
-    @overload
-    def get_wch(self) -> int | str: ...
-    @overload
-    def get_wch(self, y: int, x: int) -> int | str: ...
+    if sys.version_info < (3, 12) or sys.platform != "darwin":
+        # The support for macos was dropped in 3.12
+        @overload
+        def get_wch(self) -> int | str: ...
+        @overload
+        def get_wch(self, y: int, x: int) -> int | str: ...
+
     @overload
     def getkey(self) -> str: ...
     @overload
@@ -494,7 +500,7 @@ class window:  # undocumented
     def instr(self, y: int, x: int, n: int = ...) -> bytes: ...
     def is_linetouched(self, line: int, /) -> bool: ...
     def is_wintouched(self) -> bool: ...
-    def keypad(self, yes: bool, /) -> None: ...
+    def keypad(self, yes: bool) -> None: ...
     def leaveok(self, yes: bool) -> None: ...
     def move(self, new_y: int, new_x: int) -> None: ...
     def mvderwin(self, y: int, x: int) -> None: ...
@@ -506,18 +512,18 @@ class window:  # undocumented
     @overload
     def noutrefresh(self, pminrow: int, pmincol: int, sminrow: int, smincol: int, smaxrow: int, smaxcol: int) -> None: ...
     @overload
-    def overlay(self, destwin: window) -> None: ...
+    def overlay(self, destwin: _CursesWindow) -> None: ...
     @overload
     def overlay(
-        self, destwin: window, sminrow: int, smincol: int, dminrow: int, dmincol: int, dmaxrow: int, dmaxcol: int
+        self, destwin: _CursesWindow, sminrow: int, smincol: int, dminrow: int, dmincol: int, dmaxrow: int, dmaxcol: int
     ) -> None: ...
     @overload
-    def overwrite(self, destwin: window) -> None: ...
+    def overwrite(self, destwin: _CursesWindow) -> None: ...
     @overload
     def overwrite(
-        self, destwin: window, sminrow: int, smincol: int, dminrow: int, dmincol: int, dmaxrow: int, dmaxcol: int
+        self, destwin: _CursesWindow, sminrow: int, smincol: int, dminrow: int, dmincol: int, dmaxrow: int, dmaxcol: int
     ) -> None: ...
-    def putwin(self, file: SupportsWrite[bytes], /) -> None: ...
+    def putwin(self, file: IO[Any], /) -> None: ...
     def redrawln(self, beg: int, num: int, /) -> None: ...
     def redrawwin(self) -> None: ...
     @overload
@@ -531,13 +537,13 @@ class window:  # undocumented
     def standend(self) -> None: ...
     def standout(self) -> None: ...
     @overload
-    def subpad(self, begin_y: int, begin_x: int) -> window: ...
+    def subpad(self, begin_y: int, begin_x: int) -> _CursesWindow: ...
     @overload
-    def subpad(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> window: ...
+    def subpad(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> _CursesWindow: ...
     @overload
-    def subwin(self, begin_y: int, begin_x: int) -> window: ...
+    def subwin(self, begin_y: int, begin_x: int) -> _CursesWindow: ...
     @overload
-    def subwin(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> window: ...
+    def subwin(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> _CursesWindow: ...
     def syncdown(self) -> None: ...
     def syncok(self, flag: bool) -> None: ...
     def syncup(self) -> None: ...
@@ -550,4 +556,10 @@ class window:  # undocumented
     @overload
     def vline(self, y: int, x: int, ch: _ChType, n: int) -> None: ...
 
+class _ncurses_version(NamedTuple):
+    major: int
+    minor: int
+    patch: int
+
 ncurses_version: _ncurses_version
+window = _CursesWindow  # undocumented

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_decimal.pyi

@@ -1,54 +1,37 @@
 import numbers
-from _decimal import (
-    HAVE_CONTEXTVAR as HAVE_CONTEXTVAR,
-    HAVE_THREADS as HAVE_THREADS,
-    MAX_EMAX as MAX_EMAX,
-    MAX_PREC as MAX_PREC,
-    MIN_EMIN as MIN_EMIN,
-    MIN_ETINY as MIN_ETINY,
-    ROUND_05UP as ROUND_05UP,
-    ROUND_CEILING as ROUND_CEILING,
-    ROUND_DOWN as ROUND_DOWN,
-    ROUND_FLOOR as ROUND_FLOOR,
-    ROUND_HALF_DOWN as ROUND_HALF_DOWN,
-    ROUND_HALF_EVEN as ROUND_HALF_EVEN,
-    ROUND_HALF_UP as ROUND_HALF_UP,
-    ROUND_UP as ROUND_UP,
-    BasicContext as BasicContext,
-    DefaultContext as DefaultContext,
-    ExtendedContext as ExtendedContext,
-    __libmpdec_version__ as __libmpdec_version__,
-    __version__ as __version__,
-    getcontext as getcontext,
-    localcontext as localcontext,
-    setcontext as setcontext,
-)
+import sys
 from collections.abc import Container, Sequence
 from types import TracebackType
-from typing import Any, ClassVar, Literal, NamedTuple, final, overload, type_check_only
+from typing import Any, ClassVar, Final, Literal, NamedTuple, overload
 from typing_extensions import Self, TypeAlias
 
 _Decimal: TypeAlias = Decimal | int
 _DecimalNew: TypeAlias = Decimal | float | str | tuple[int, Sequence[int], int]
 _ComparableNum: TypeAlias = Decimal | float | numbers.Rational
-_TrapType: TypeAlias = type[DecimalException]
 
-# At runtime, these classes are implemented in C as part of "_decimal".
-# However, they consider themselves to live in "decimal", so we'll put them here.
-
-# This type isn't exposed at runtime. It calls itself decimal.ContextManager
-@final
-@type_check_only
-class _ContextManager:
-    def __init__(self, new_context: Context) -> None: ...
-    def __enter__(self) -> Context: ...
-    def __exit__(self, t: type[BaseException] | None, v: BaseException | None, tb: TracebackType | None) -> None: ...
+__version__: Final[str]
+__libmpdec_version__: Final[str]
 
 class DecimalTuple(NamedTuple):
     sign: int
     digits: tuple[int, ...]
     exponent: int | Literal["n", "N", "F"]
 
+ROUND_DOWN: str
+ROUND_HALF_UP: str
+ROUND_HALF_EVEN: str
+ROUND_CEILING: str
+ROUND_FLOOR: str
+ROUND_UP: str
+ROUND_HALF_DOWN: str
+ROUND_05UP: str
+HAVE_CONTEXTVAR: bool
+HAVE_THREADS: bool
+MAX_EMAX: int
+MAX_PREC: int
+MIN_EMIN: int
+MIN_ETINY: int
+
 class DecimalException(ArithmeticError): ...
 class Clamped(DecimalException): ...
 class InvalidOperation(DecimalException): ...
@@ -64,6 +47,26 @@ class Overflow(Inexact, Rounded): ...
 class Underflow(Inexact, Rounded, Subnormal): ...
 class FloatOperation(DecimalException, TypeError): ...
 
+def setcontext(context: Context, /) -> None: ...
+def getcontext() -> Context: ...
+
+if sys.version_info >= (3, 11):
+    def localcontext(
+        ctx: Context | None = None,
+        *,
+        prec: int | None = ...,
+        rounding: str | None = ...,
+        Emin: int | None = ...,
+        Emax: int | None = ...,
+        capitals: int | None = ...,
+        clamp: int | None = ...,
+        traps: dict[_TrapType, bool] | None = ...,
+        flags: dict[_TrapType, bool] | None = ...,
+    ) -> _ContextManager: ...
+
+else:
+    def localcontext(ctx: Context | None = None) -> _ContextManager: ...
+
 class Decimal:
     def __new__(cls, value: _DecimalNew = ..., context: Context | None = ...) -> Self: ...
     @classmethod
@@ -165,6 +168,15 @@ class Decimal:
     def __deepcopy__(self, memo: Any, /) -> Self: ...
     def __format__(self, specifier: str, context: Context | None = ..., /) -> str: ...
 
+class _ContextManager:
+    new_context: Context
+    saved_context: Context
+    def __init__(self, new_context: Context) -> None: ...
+    def __enter__(self) -> Context: ...
+    def __exit__(self, t: type[BaseException] | None, v: BaseException | None, tb: TracebackType | None) -> None: ...
+
+_TrapType: TypeAlias = type[DecimalException]
+
 class Context:
     # TODO: Context doesn't allow you to delete *any* attributes from instances of the class at runtime,
     # even settable attributes like `prec` and `rounding`,
@@ -189,6 +201,7 @@ class Context:
         clamp: int | None = ...,
         flags: None | dict[_TrapType, bool] | Container[_TrapType] = ...,
         traps: None | dict[_TrapType, bool] | Container[_TrapType] = ...,
+        _ignored_flags: list[_TrapType] | None = ...,
     ) -> None: ...
     def __reduce__(self) -> tuple[type[Self], tuple[Any, ...]]: ...
     def clear_flags(self) -> None: ...
@@ -262,3 +275,7 @@ class Context:
     def to_integral_exact(self, x: _Decimal, /) -> Decimal: ...
     def to_integral_value(self, x: _Decimal, /) -> Decimal: ...
     def to_integral(self, x: _Decimal, /) -> Decimal: ...
+
+DefaultContext: Context
+BasicContext: Context
+ExtendedContext: Context

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_dummy_threading.pyi

@@ -0,0 +1,164 @@
+import sys
+from _thread import _excepthook, _ExceptHookArgs
+from _typeshed import ProfileFunction, TraceFunction
+from collections.abc import Callable, Iterable, Mapping
+from types import TracebackType
+from typing import Any, TypeVar
+
+_T = TypeVar("_T")
+
+__all__ = [
+    "get_ident",
+    "active_count",
+    "Condition",
+    "current_thread",
+    "enumerate",
+    "main_thread",
+    "TIMEOUT_MAX",
+    "Event",
+    "Lock",
+    "RLock",
+    "Semaphore",
+    "BoundedSemaphore",
+    "Thread",
+    "Barrier",
+    "BrokenBarrierError",
+    "Timer",
+    "ThreadError",
+    "setprofile",
+    "settrace",
+    "local",
+    "stack_size",
+    "ExceptHookArgs",
+    "excepthook",
+]
+
+def active_count() -> int: ...
+def current_thread() -> Thread: ...
+def currentThread() -> Thread: ...
+def get_ident() -> int: ...
+def enumerate() -> list[Thread]: ...
+def main_thread() -> Thread: ...
+def settrace(func: TraceFunction) -> None: ...
+def setprofile(func: ProfileFunction | None) -> None: ...
+def stack_size(size: int | None = None) -> int: ...
+
+TIMEOUT_MAX: float
+
+class ThreadError(Exception): ...
+
+class local:
+    def __getattribute__(self, name: str) -> Any: ...
+    def __setattr__(self, name: str, value: Any) -> None: ...
+    def __delattr__(self, name: str) -> None: ...
+
+class Thread:
+    name: str
+    daemon: bool
+    @property
+    def ident(self) -> int | None: ...
+    def __init__(
+        self,
+        group: None = None,
+        target: Callable[..., object] | None = None,
+        name: str | None = None,
+        args: Iterable[Any] = (),
+        kwargs: Mapping[str, Any] | None = None,
+        *,
+        daemon: bool | None = None,
+    ) -> None: ...
+    def start(self) -> None: ...
+    def run(self) -> None: ...
+    def join(self, timeout: float | None = None) -> None: ...
+    def getName(self) -> str: ...
+    def setName(self, name: str) -> None: ...
+    @property
+    def native_id(self) -> int | None: ...  # only available on some platforms
+    def is_alive(self) -> bool: ...
+    if sys.version_info < (3, 9):
+        def isAlive(self) -> bool: ...
+
+    def isDaemon(self) -> bool: ...
+    def setDaemon(self, daemonic: bool) -> None: ...
+
+class _DummyThread(Thread): ...
+
+class Lock:
+    def __enter__(self) -> bool: ...
+    def __exit__(
+        self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
+    ) -> bool | None: ...
+    def acquire(self, blocking: bool = ..., timeout: float = ...) -> bool: ...
+    def release(self) -> None: ...
+    def locked(self) -> bool: ...
+
+class _RLock:
+    def __enter__(self) -> bool: ...
+    def __exit__(
+        self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
+    ) -> bool | None: ...
+    def acquire(self, blocking: bool = True, timeout: float = -1) -> bool: ...
+    def release(self) -> None: ...
+
+RLock = _RLock
+
+class Condition:
+    def __init__(self, lock: Lock | _RLock | None = None) -> None: ...
+    def __enter__(self) -> bool: ...
+    def __exit__(
+        self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
+    ) -> bool | None: ...
+    def acquire(self, blocking: bool = ..., timeout: float = ...) -> bool: ...
+    def release(self) -> None: ...
+    def wait(self, timeout: float | None = None) -> bool: ...
+    def wait_for(self, predicate: Callable[[], _T], timeout: float | None = None) -> _T: ...
+    def notify(self, n: int = 1) -> None: ...
+    def notify_all(self) -> None: ...
+    def notifyAll(self) -> None: ...
+
+class Semaphore:
+    def __init__(self, value: int = 1) -> None: ...
+    def __exit__(
+        self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
+    ) -> bool | None: ...
+    def acquire(self, blocking: bool = True, timeout: float | None = None) -> bool: ...
+    def __enter__(self, blocking: bool = True, timeout: float | None = None) -> bool: ...
+    if sys.version_info >= (3, 9):
+        def release(self, n: int = ...) -> None: ...
+    else:
+        def release(self) -> None: ...
+
+class BoundedSemaphore(Semaphore): ...
+
+class Event:
+    def is_set(self) -> bool: ...
+    def set(self) -> None: ...
+    def clear(self) -> None: ...
+    def wait(self, timeout: float | None = None) -> bool: ...
+
+excepthook = _excepthook
+ExceptHookArgs = _ExceptHookArgs
+
+class Timer(Thread):
+    def __init__(
+        self,
+        interval: float,
+        function: Callable[..., object],
+        args: Iterable[Any] | None = None,
+        kwargs: Mapping[str, Any] | None = None,
+    ) -> None: ...
+    def cancel(self) -> None: ...
+
+class Barrier:
+    @property
+    def parties(self) -> int: ...
+    @property
+    def n_waiting(self) -> int: ...
+    @property
+    def broken(self) -> bool: ...
+    def __init__(self, parties: int, action: Callable[[], None] | None = None, timeout: float | None = None) -> None: ...
+    def wait(self, timeout: float | None = None) -> int: ...
+    def reset(self) -> None: ...
+    def abort(self) -> None: ...
+
+class BrokenBarrierError(RuntimeError): ...

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_interpchannels.pyi

@@ -1,5 +1,5 @@
 from _typeshed import structseq
-from typing import Any, Final, Literal, SupportsIndex, final
+from typing import Final, Literal, SupportsIndex, final
 from typing_extensions import Buffer, Self
 
 class ChannelError(RuntimeError): ...
@@ -72,15 +72,13 @@ class ChannelInfo(structseq[int], tuple[bool, bool, bool, int, int, int, int, in
     @property
     def send_released(self) -> bool: ...
 
-def create(unboundop: Literal[1, 2, 3]) -> ChannelID: ...
+def create() -> ChannelID: ...
 def destroy(cid: SupportsIndex) -> None: ...
 def list_all() -> list[ChannelID]: ...
 def list_interpreters(cid: SupportsIndex, *, send: bool) -> list[int]: ...
 def send(cid: SupportsIndex, obj: object, *, blocking: bool = True, timeout: float | None = None) -> None: ...
 def send_buffer(cid: SupportsIndex, obj: Buffer, *, blocking: bool = True, timeout: float | None = None) -> None: ...
-def recv(cid: SupportsIndex, default: object = ...) -> tuple[Any, Literal[1, 2, 3]]: ...
+def recv(cid: SupportsIndex, default: object = ...) -> object: ...
 def close(cid: SupportsIndex, *, send: bool = False, recv: bool = False) -> None: ...
-def get_count(cid: SupportsIndex) -> int: ...
 def get_info(cid: SupportsIndex) -> ChannelInfo: ...
-def get_channel_defaults(cid: SupportsIndex) -> Literal[1, 2, 3]: ...
 def release(cid: SupportsIndex, *, send: bool = False, recv: bool = False, force: bool = False) -> None: ...

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_json.pyi

@@ -1,6 +1,5 @@
 from collections.abc import Callable
 from typing import Any, final
-from typing_extensions import Self
 
 @final
 class make_encoder:
@@ -20,8 +19,8 @@ class make_encoder:
     def encoder(self) -> Callable[[str], str]: ...
     @property
     def item_separator(self) -> str: ...
-    def __new__(
-        cls,
+    def __init__(
+        self,
         markers: dict[int, Any] | None,
         default: Callable[[Any], Any],
         encoder: Callable[[str], str],
@@ -31,7 +30,7 @@ class make_encoder:
         sort_keys: bool,
         skipkeys: bool,
         allow_nan: bool,
-    ) -> Self: ...
+    ) -> None: ...
     def __call__(self, obj: object, _current_indent_level: int) -> Any: ...
 
 @final
@@ -43,9 +42,8 @@ class make_scanner:
     parse_float: Any
     strict: bool
     # TODO: 'context' needs the attrs above (ducktype), but not __call__.
-    def __new__(cls, context: make_scanner) -> Self: ...
+    def __init__(self, context: make_scanner) -> None: ...
     def __call__(self, string: str, index: int) -> tuple[Any, int]: ...
 
-def encode_basestring(s: str, /) -> str: ...
 def encode_basestring_ascii(s: str, /) -> str: ...
 def scanstring(string: str, end: int, strict: bool = ...) -> tuple[str, int]: ...

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_locale.pyi

@@ -0,0 +1,100 @@
+import sys
+from _typeshed import StrPath
+from collections.abc import Mapping
+
+LC_CTYPE: int
+LC_COLLATE: int
+LC_TIME: int
+LC_MONETARY: int
+LC_NUMERIC: int
+LC_ALL: int
+CHAR_MAX: int
+
+def setlocale(category: int, locale: str | None = None, /) -> str: ...
+def localeconv() -> Mapping[str, int | str | list[int]]: ...
+
+if sys.version_info >= (3, 11):
+    def getencoding() -> str: ...
+
+def strcoll(os1: str, os2: str, /) -> int: ...
+def strxfrm(string: str, /) -> str: ...
+
+# native gettext functions
+# https://docs.python.org/3/library/locale.html#access-to-message-catalogs
+# https://github.com/python/cpython/blob/f4c03484da59049eb62a9bf7777b963e2267d187/Modules/_localemodule.c#L626
+if sys.platform != "win32":
+    LC_MESSAGES: int
+
+    ABDAY_1: int
+    ABDAY_2: int
+    ABDAY_3: int
+    ABDAY_4: int
+    ABDAY_5: int
+    ABDAY_6: int
+    ABDAY_7: int
+
+    ABMON_1: int
+    ABMON_2: int
+    ABMON_3: int
+    ABMON_4: int
+    ABMON_5: int
+    ABMON_6: int
+    ABMON_7: int
+    ABMON_8: int
+    ABMON_9: int
+    ABMON_10: int
+    ABMON_11: int
+    ABMON_12: int
+
+    DAY_1: int
+    DAY_2: int
+    DAY_3: int
+    DAY_4: int
+    DAY_5: int
+    DAY_6: int
+    DAY_7: int
+
+    ERA: int
+    ERA_D_T_FMT: int
+    ERA_D_FMT: int
+    ERA_T_FMT: int
+
+    MON_1: int
+    MON_2: int
+    MON_3: int
+    MON_4: int
+    MON_5: int
+    MON_6: int
+    MON_7: int
+    MON_8: int
+    MON_9: int
+    MON_10: int
+    MON_11: int
+    MON_12: int
+
+    CODESET: int
+    D_T_FMT: int
+    D_FMT: int
+    T_FMT: int
+    T_FMT_AMPM: int
+    AM_STR: int
+    PM_STR: int
+
+    RADIXCHAR: int
+    THOUSEP: int
+    YESEXPR: int
+    NOEXPR: int
+    CRNCYSTR: int
+    ALT_DIGITS: int
+
+    def nl_langinfo(key: int, /) -> str: ...
+
+    # This is dependent on `libintl.h` which is a part of `gettext`
+    # system dependency. These functions might be missing.
+    # But, we always say that they are present.
+    def gettext(msg: str, /) -> str: ...
+    def dgettext(domain: str | None, msg: str, /) -> str: ...
+    def dcgettext(domain: str | None, msg: str, category: int, /) -> str: ...
+    def textdomain(domain: str | None, /) -> str: ...
+    def bindtextdomain(domain: str, dir: StrPath | None, /) -> str: ...
+    def bind_textdomain_codeset(domain: str, codeset: str | None, /) -> str | None: ...

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_operator.pyi

@@ -1,16 +1,18 @@
 import sys
 from _typeshed import SupportsGetItem
 from collections.abc import Callable, Container, Iterable, MutableMapping, MutableSequence, Sequence
-from operator import attrgetter as attrgetter, itemgetter as itemgetter, methodcaller as methodcaller
-from typing import Any, AnyStr, Protocol, SupportsAbs, SupportsIndex, TypeVar, overload
-from typing_extensions import ParamSpec, TypeAlias, TypeIs
+from typing import Any, AnyStr, Generic, Protocol, SupportsAbs, SupportsIndex, TypeVar, final, overload
+from typing_extensions import ParamSpec, TypeAlias, TypeVarTuple, Unpack
 
 _R = TypeVar("_R")
 _T = TypeVar("_T")
 _T_co = TypeVar("_T_co", covariant=True)
+_T1 = TypeVar("_T1")
+_T2 = TypeVar("_T2")
 _K = TypeVar("_K")
 _V = TypeVar("_V")
 _P = ParamSpec("_P")
+_Ts = TypeVarTuple("_Ts")
 
 # The following protocols return "Any" instead of bool, since the comparison
 # operators can be overloaded to return an arbitrary object. For example,
@@ -90,6 +92,40 @@ def setitem(a: MutableSequence[_T], b: slice, c: Sequence[_T], /) -> None: ...
 @overload
 def setitem(a: MutableMapping[_K, _V], b: _K, c: _V, /) -> None: ...
 def length_hint(obj: object, default: int = 0, /) -> int: ...
+@final
+class attrgetter(Generic[_T_co]):
+    @overload
+    def __new__(cls, attr: str, /) -> attrgetter[Any]: ...
+    @overload
+    def __new__(cls, attr: str, attr2: str, /) -> attrgetter[tuple[Any, Any]]: ...
+    @overload
+    def __new__(cls, attr: str, attr2: str, attr3: str, /) -> attrgetter[tuple[Any, Any, Any]]: ...
+    @overload
+    def __new__(cls, attr: str, attr2: str, attr3: str, attr4: str, /) -> attrgetter[tuple[Any, Any, Any, Any]]: ...
+    @overload
+    def __new__(cls, attr: str, /, *attrs: str) -> attrgetter[tuple[Any, ...]]: ...
+    def __call__(self, obj: Any, /) -> _T_co: ...
+
+@final
+class itemgetter(Generic[_T_co]):
+    @overload
+    def __new__(cls, item: _T, /) -> itemgetter[_T]: ...
+    @overload
+    def __new__(cls, item1: _T1, item2: _T2, /, *items: Unpack[_Ts]) -> itemgetter[tuple[_T1, _T2, Unpack[_Ts]]]: ...
+    # __key: _KT_contra in SupportsGetItem seems to be causing variance issues, ie:
+    # TypeVar "_KT_contra@SupportsGetItem" is contravariant
+    #   "tuple[int, int]" is incompatible with protocol "SupportsIndex"
+    # preventing [_T_co, ...] instead of [Any, ...]
+    #
+    # A suspected mypy issue prevents using [..., _T] instead of [..., Any] here.
+    # https://github.com/python/mypy/issues/14032
+    def __call__(self, obj: SupportsGetItem[Any, Any]) -> Any: ...
+
+@final
+class methodcaller:
+    def __init__(self, name: str, /, *args: Any, **kwargs: Any) -> None: ...
+    def __call__(self, obj: Any) -> Any: ...
+
 def iadd(a: Any, b: Any, /) -> Any: ...
 def iand(a: Any, b: Any, /) -> Any: ...
 def iconcat(a: Any, b: Any, /) -> Any: ...
@@ -109,7 +145,3 @@ if sys.version_info >= (3, 11):
     def call(obj: Callable[_P, _R], /, *args: _P.args, **kwargs: _P.kwargs) -> _R: ...
 
 def _compare_digest(a: AnyStr, b: AnyStr, /) -> bool: ...
-
-if sys.version_info >= (3, 14):
-    def is_none(a: object, /) -> TypeIs[None]: ...
-    def is_not_none(a: _T | None, /) -> TypeIs[_T]: ...

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_osx_support.pyi

@@ -1,5 +1,5 @@
 from collections.abc import Iterable, Sequence
-from typing import Final, TypeVar
+from typing import TypeVar
 
 _T = TypeVar("_T")
 _K = TypeVar("_K")
@@ -7,15 +7,15 @@ _V = TypeVar("_V")
 
 __all__ = ["compiler_fixup", "customize_config_vars", "customize_compiler", "get_platform_osx"]
 
-_UNIVERSAL_CONFIG_VARS: Final[tuple[str, ...]]  # undocumented
-_COMPILER_CONFIG_VARS: Final[tuple[str, ...]]  # undocumented
-_INITPRE: Final[str]  # undocumented
+_UNIVERSAL_CONFIG_VARS: tuple[str, ...]  # undocumented
+_COMPILER_CONFIG_VARS: tuple[str, ...]  # undocumented
+_INITPRE: str  # undocumented
 
 def _find_executable(executable: str, path: str | None = None) -> str | None: ...  # undocumented
 def _read_output(commandstring: str, capture_stderr: bool = False) -> str | None: ...  # undocumented
 def _find_build_tool(toolname: str) -> str: ...  # undocumented
 
-_SYSTEM_VERSION: Final[str | None]  # undocumented
+_SYSTEM_VERSION: str | None  # undocumented
 
 def _get_system_version() -> str: ...  # undocumented
 def _remove_original_values(_config_vars: dict[str, str]) -> None: ...  # undocumented

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_posixsubprocess.pyi

@@ -4,6 +4,7 @@ from collections.abc import Callable, Sequence
 from typing import SupportsIndex
 
 if sys.platform != "win32":
+    def cloexec_pipe() -> tuple[int, int]: ...
     def fork_exec(
         args: Sequence[StrOrBytesPath] | None,
         executable_list: Sequence[bytes],

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_sitebuiltins.pyi

@@ -1,4 +1,3 @@
-import sys
 from collections.abc import Iterable
 from typing import ClassVar, Literal, NoReturn
 
@@ -6,7 +5,7 @@ class Quitter:
     name: str
     eof: str
     def __init__(self, name: str, eof: str) -> None: ...
-    def __call__(self, code: sys._ExitCode = None) -> NoReturn: ...
+    def __call__(self, code: int | None = None) -> NoReturn: ...
 
 class _Printer:
     MAXLINES: ClassVar[Literal[23]]
@@ -14,4 +13,4 @@ class _Printer:
     def __call__(self) -> None: ...
 
 class _Helper:
-    def __call__(self, request: object = ...) -> None: ...
+    def __call__(self, request: object) -> None: ...

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_socket.pyi

@@ -1,9 +1,8 @@
 import sys
 from _typeshed import ReadableBuffer, WriteableBuffer
 from collections.abc import Iterable
-from socket import error as error, gaierror as gaierror, herror as herror, timeout as timeout
 from typing import Any, SupportsIndex, overload
-from typing_extensions import CapsuleType, TypeAlias
+from typing_extensions import TypeAlias
 
 _CMSG: TypeAlias = tuple[int, int, bytes]
 _CMSGArg: TypeAlias = tuple[int, int, ReadableBuffer]
@@ -72,16 +71,13 @@ SO_SNDBUF: int
 SO_SNDLOWAT: int
 SO_SNDTIMEO: int
 SO_TYPE: int
-if sys.platform != "linux":
-    SO_USELOOPBACK: int
+SO_USELOOPBACK: int
 if sys.platform == "win32":
     SO_EXCLUSIVEADDRUSE: int
 if sys.platform != "win32":
     SO_REUSEPORT: int
-    if sys.platform != "darwin" or sys.version_info >= (3, 13):
-        SO_BINDTODEVICE: int
-
 if sys.platform != "win32" and sys.platform != "darwin":
+    SO_BINDTODEVICE: int
     SO_DOMAIN: int
     SO_MARK: int
     SO_PASSCRED: int
@@ -90,10 +86,7 @@ if sys.platform != "win32" and sys.platform != "darwin":
     SO_PEERSEC: int
     SO_PRIORITY: int
     SO_PROTOCOL: int
-if sys.platform != "win32" and sys.platform != "darwin" and sys.platform != "linux":
     SO_SETFIB: int
-if sys.platform == "linux" and sys.version_info >= (3, 13):
-    SO_BINDTOIFINDEX: int
 
 SOMAXCONN: int
 
@@ -105,32 +98,27 @@ MSG_TRUNC: int
 MSG_WAITALL: int
 if sys.platform != "win32":
     MSG_DONTWAIT: int
+    MSG_EOF: int
     MSG_EOR: int
     MSG_NOSIGNAL: int  # Sometimes this exists on darwin, sometimes not
 if sys.platform != "darwin":
-    MSG_ERRQUEUE: int
-if sys.platform == "win32":
     MSG_BCAST: int
+    MSG_ERRQUEUE: int
     MSG_MCAST: int
 if sys.platform != "win32" and sys.platform != "darwin":
+    MSG_BTAG: int
     MSG_CMSG_CLOEXEC: int
     MSG_CONFIRM: int
+    MSG_ETAG: int
     MSG_FASTOPEN: int
     MSG_MORE: int
-if sys.platform != "win32" and sys.platform != "linux":
-    MSG_EOF: int
-if sys.platform != "win32" and sys.platform != "linux" and sys.platform != "darwin":
     MSG_NOTIFICATION: int
-    MSG_BTAG: int  # Not FreeBSD either
-    MSG_ETAG: int  # Not FreeBSD either
 
 SOL_IP: int
 SOL_SOCKET: int
 SOL_TCP: int
 SOL_UDP: int
 if sys.platform != "win32" and sys.platform != "darwin":
-    # Defined in socket.h for Linux, but these aren't always present for
-    # some reason.
     SOL_ATALK: int
     SOL_AX25: int
     SOL_HCI: int
@@ -139,11 +127,10 @@ if sys.platform != "win32" and sys.platform != "darwin":
     SOL_ROSE: int
 
 if sys.platform != "win32":
+    SCM_CREDS: int
     SCM_RIGHTS: int
 if sys.platform != "win32" and sys.platform != "darwin":
     SCM_CREDENTIALS: int
-if sys.platform != "win32" and sys.platform != "linux":
-    SCM_CREDS: int
 
 IPPROTO_ICMP: int
 IPPROTO_IP: int
@@ -155,22 +142,21 @@ IPPROTO_DSTOPTS: int
 IPPROTO_EGP: int
 IPPROTO_ESP: int
 IPPROTO_FRAGMENT: int
+IPPROTO_GGP: int
 IPPROTO_HOPOPTS: int
 IPPROTO_ICMPV6: int
 IPPROTO_IDP: int
 IPPROTO_IGMP: int
+IPPROTO_IPV4: int
 IPPROTO_IPV6: int
+IPPROTO_MAX: int
+IPPROTO_ND: int
 IPPROTO_NONE: int
 IPPROTO_PIM: int
 IPPROTO_PUP: int
 IPPROTO_ROUTING: int
 IPPROTO_SCTP: int
-if sys.platform != "linux":
-    IPPROTO_GGP: int
-    IPPROTO_IPV4: int
-    IPPROTO_MAX: int
-    IPPROTO_ND: int
-if sys.platform == "win32":
+if sys.platform != "darwin":
     IPPROTO_CBT: int
     IPPROTO_ICLFXBM: int
     IPPROTO_IGP: int
@@ -179,19 +165,18 @@ if sys.platform == "win32":
     IPPROTO_RDP: int
     IPPROTO_ST: int
 if sys.platform != "win32":
+    IPPROTO_EON: int
     IPPROTO_GRE: int
+    IPPROTO_HELLO: int
+    IPPROTO_IPCOMP: int
     IPPROTO_IPIP: int
     IPPROTO_RSVP: int
     IPPROTO_TP: int
-if sys.platform != "win32" and sys.platform != "linux":
-    IPPROTO_EON: int
-    IPPROTO_HELLO: int
-    IPPROTO_IPCOMP: int
     IPPROTO_XTP: int
-if sys.platform != "win32" and sys.platform != "darwin" and sys.platform != "linux":
-    IPPROTO_BIP: int  # Not FreeBSD either
-    IPPROTO_MOBILE: int  # Not FreeBSD either
-    IPPROTO_VRRP: int  # Not FreeBSD either
+if sys.platform != "win32" and sys.platform != "darwin":
+    IPPROTO_BIP: int
+    IPPROTO_MOBILE: int
+    IPPROTO_VRRP: int
 if sys.version_info >= (3, 9) and sys.platform == "linux":
     # Availability: Linux >= 2.6.20, FreeBSD >= 10.1
     IPPROTO_UDPLITE: int
@@ -216,10 +201,11 @@ IP_MULTICAST_IF: int
 IP_MULTICAST_LOOP: int
 IP_MULTICAST_TTL: int
 IP_OPTIONS: int
-if sys.platform != "linux":
-    IP_RECVDSTADDR: int
+IP_RECVDSTADDR: int
 if sys.version_info >= (3, 10):
     IP_RECVTOS: int
+elif sys.platform != "win32" and sys.platform != "darwin":
+    IP_RECVTOS: int
 IP_TOS: int
 IP_TTL: int
 if sys.platform != "win32":
@@ -231,7 +217,6 @@ if sys.platform != "win32":
     IP_RETOPTS: int
 if sys.platform != "win32" and sys.platform != "darwin":
     IP_TRANSPARENT: int
-if sys.platform != "win32" and sys.platform != "darwin" and sys.version_info >= (3, 11):
     IP_BIND_ADDRESS_NO_PORT: int
 if sys.version_info >= (3, 12):
     IP_ADD_SOURCE_MEMBERSHIP: int
@@ -269,9 +254,6 @@ if sys.platform != "win32":
         IPV6_RECVPATHMTU: int
         IPV6_RECVPKTINFO: int
         IPV6_RTHDRDSTOPTS: int
-
-if sys.platform != "win32" and sys.platform != "linux":
-    if sys.version_info >= (3, 9) or sys.platform != "darwin":
         IPV6_USE_MIN_MTU: int
 
 EAI_AGAIN: int
@@ -285,12 +267,11 @@ EAI_SERVICE: int
 EAI_SOCKTYPE: int
 if sys.platform != "win32":
     EAI_ADDRFAMILY: int
-    EAI_OVERFLOW: int
-    EAI_SYSTEM: int
-if sys.platform != "win32" and sys.platform != "linux":
     EAI_BADHINTS: int
     EAI_MAX: int
+    EAI_OVERFLOW: int
     EAI_PROTOCOL: int
+    EAI_SYSTEM: int
 
 AI_ADDRCONFIG: int
 AI_ALL: int
@@ -299,7 +280,7 @@ AI_NUMERICHOST: int
 AI_NUMERICSERV: int
 AI_PASSIVE: int
 AI_V4MAPPED: int
-if sys.platform != "win32" and sys.platform != "linux":
+if sys.platform != "win32":
     AI_DEFAULT: int
     AI_MASK: int
     AI_V4MAPPED_CFG: int
@@ -311,8 +292,6 @@ NI_NAMEREQD: int
 NI_NOFQDN: int
 NI_NUMERICHOST: int
 NI_NUMERICSERV: int
-if sys.platform == "linux" and sys.version_info >= (3, 13):
-    NI_IDN: int
 
 TCP_FASTOPEN: int
 TCP_KEEPCNT: int
@@ -338,27 +317,6 @@ if sys.platform != "win32" and sys.platform != "darwin":
     TCP_SYNCNT: int
     TCP_USER_TIMEOUT: int
     TCP_WINDOW_CLAMP: int
-if sys.platform == "linux" and sys.version_info >= (3, 12):
-    TCP_CC_INFO: int
-    TCP_FASTOPEN_CONNECT: int
-    TCP_FASTOPEN_KEY: int
-    TCP_FASTOPEN_NO_COOKIE: int
-    TCP_INQ: int
-    TCP_MD5SIG: int
-    TCP_MD5SIG_EXT: int
-    TCP_QUEUE_SEQ: int
-    TCP_REPAIR: int
-    TCP_REPAIR_OPTIONS: int
-    TCP_REPAIR_QUEUE: int
-    TCP_REPAIR_WINDOW: int
-    TCP_SAVED_SYN: int
-    TCP_SAVE_SYN: int
-    TCP_THIN_DUPACK: int
-    TCP_THIN_LINEAR_TIMEOUTS: int
-    TCP_TIMESTAMP: int
-    TCP_TX_DELAY: int
-    TCP_ULP: int
-    TCP_ZEROCOPY_RECEIVE: int
 
 # --------------------
 # Specifically documented constants
@@ -375,13 +333,12 @@ if sys.platform == "linux":
     CAN_ERR_FLAG: int
     CAN_ERR_MASK: int
     CAN_RAW: int
+    CAN_RAW_ERR_FILTER: int
     CAN_RAW_FILTER: int
     CAN_RAW_LOOPBACK: int
     CAN_RAW_RECV_OWN_MSGS: int
     CAN_RTR_FLAG: int
     CAN_SFF_MASK: int
-    if sys.version_info < (3, 11):
-        CAN_RAW_ERR_FILTER: int
 
 if sys.platform == "linux":
     # Availability: Linux >= 2.6.25
@@ -479,13 +436,12 @@ if sys.platform == "linux":
     AF_RDS: int
     PF_RDS: int
     SOL_RDS: int
-    # These are present in include/linux/rds.h but don't always show up
-    # here.
     RDS_CANCEL_SENT_TO: int
     RDS_CMSG_RDMA_ARGS: int
     RDS_CMSG_RDMA_DEST: int
     RDS_CMSG_RDMA_MAP: int
     RDS_CMSG_RDMA_STATUS: int
+    RDS_CMSG_RDMA_UPDATE: int
     RDS_CONG_MONITOR: int
     RDS_FREE_MR: int
     RDS_GET_MR: int
@@ -499,10 +455,6 @@ if sys.platform == "linux":
     RDS_RDMA_USE_ONCE: int
     RDS_RECVERR: int
 
-    # This is supported by CPython but doesn't seem to be a real thing.
-    # The closest existing constant in rds.h is RDS_CMSG_CONG_UPDATE
-    # RDS_CMSG_RDMA_UPDATE: int
-
 if sys.platform == "win32":
     SIO_RCVALL: int
     SIO_KEEPALIVE_VALS: int
@@ -569,17 +521,16 @@ if sys.platform == "linux":
 if sys.platform != "win32" or sys.version_info >= (3, 9):
     # Documented as only available on BSD, macOS, but empirically sometimes
     # available on Windows
-    if sys.platform != "linux":
-        AF_LINK: int
+    AF_LINK: int
 
 has_ipv6: bool
 
-if sys.platform != "darwin" and sys.platform != "linux":
+if sys.platform != "darwin":
     if sys.platform != "win32" or sys.version_info >= (3, 9):
         BDADDR_ANY: str
         BDADDR_LOCAL: str
 
-if sys.platform != "win32" and sys.platform != "darwin" and sys.platform != "linux":
+if sys.platform != "win32" and sys.platform != "darwin":
     HCI_FILTER: int  # not in NetBSD or DragonFlyBSD
     HCI_TIME_STAMP: int  # not in FreeBSD, NetBSD, or DragonFlyBSD
     HCI_DATA_DIR: int  # not in FreeBSD, NetBSD, or DragonFlyBSD
@@ -628,37 +579,36 @@ if sys.version_info >= (3, 12):
 if sys.platform == "linux":
     # Netlink is defined by Linux
     AF_NETLINK: int
+    NETLINK_ARPD: int
     NETLINK_CRYPTO: int
     NETLINK_DNRTMSG: int
     NETLINK_FIREWALL: int
     NETLINK_IP6_FW: int
     NETLINK_NFLOG: int
+    NETLINK_ROUTE6: int
     NETLINK_ROUTE: int
+    NETLINK_SKIP: int
+    NETLINK_TAPBASE: int
+    NETLINK_TCPDIAG: int
     NETLINK_USERSOCK: int
+    NETLINK_W1: int
     NETLINK_XFRM: int
-    # Technically still supported by CPython
-    # NETLINK_ARPD: int  # linux 2.0 to 2.6.12 (EOL August 2005)
-    # NETLINK_ROUTE6: int  # linux 2.2 to 2.6.12 (EOL August 2005)
-    # NETLINK_SKIP: int  # linux 2.0 to 2.6.12 (EOL August 2005)
-    # NETLINK_TAPBASE: int  # linux 2.2 to 2.6.12 (EOL August 2005)
-    # NETLINK_TCPDIAG: int  # linux 2.6.0 to 2.6.13 (EOL December 2005)
-    # NETLINK_W1: int  # linux 2.6.13 to 2.6.17 (EOL October 2006)
 
 if sys.platform == "darwin":
     PF_SYSTEM: int
     SYSPROTO_CONTROL: int
 
-if sys.platform != "darwin" and sys.platform != "linux":
+if sys.platform != "darwin":
     if sys.version_info >= (3, 9) or sys.platform != "win32":
         AF_BLUETOOTH: int
 
-if sys.platform != "win32" and sys.platform != "darwin" and sys.platform != "linux":
+if sys.platform != "win32" and sys.platform != "darwin":
     # Linux and some BSD support is explicit in the docs
     # Windows and macOS do not support in practice
     BTPROTO_HCI: int
     BTPROTO_L2CAP: int
     BTPROTO_SCO: int  # not in FreeBSD
-if sys.platform != "darwin" and sys.platform != "linux":
+if sys.platform != "darwin":
     if sys.version_info >= (3, 9) or sys.platform != "win32":
         BTPROTO_RFCOMM: int
 
@@ -685,14 +635,13 @@ AF_SNA: int
 
 if sys.platform != "win32":
     AF_ROUTE: int
-
-if sys.platform == "darwin":
     AF_SYSTEM: int
 
 if sys.platform != "darwin":
     AF_IRDA: int
 
 if sys.platform != "win32" and sys.platform != "darwin":
+    AF_AAL5: int
     AF_ASH: int
     AF_ATMPVC: int
     AF_ATMSVC: int
@@ -711,14 +660,24 @@ if sys.platform != "win32" and sys.platform != "darwin":
 
 # Miscellaneous undocumented
 
-if sys.platform != "win32" and sys.platform != "linux":
+if sys.platform != "win32":
     LOCAL_PEERCRED: int
 
 if sys.platform != "win32" and sys.platform != "darwin":
-    # Defined in linux socket.h, but this isn't always present for
-    # some reason.
     IPX_TYPE: int
 
+# ===== Exceptions =====
+
+error = OSError
+
+class herror(error): ...
+class gaierror(error): ...
+
+if sys.version_info >= (3, 10):
+    timeout = TimeoutError
+else:
+    class timeout(error): ...
+
 # ===== Classes =====
 
 class socket:
@@ -728,9 +687,8 @@ class socket:
     def type(self) -> int: ...
     @property
     def proto(self) -> int: ...
-    # F811: "Redefinition of unused `timeout`"
     @property
-    def timeout(self) -> float | None: ...  # noqa: F811
+    def timeout(self) -> float | None: ...
     if sys.platform == "win32":
         def __init__(
             self, family: int = ..., type: int = ..., proto: int = ..., fileno: SupportsIndex | bytes | None = ...
@@ -830,9 +788,7 @@ def inet_ntoa(packed_ip: ReadableBuffer, /) -> str: ...
 def inet_pton(address_family: int, ip_string: str, /) -> bytes: ...
 def inet_ntop(address_family: int, packed_ip: ReadableBuffer, /) -> str: ...
 def getdefaulttimeout() -> float | None: ...
-
-# F811: "Redefinition of unused `timeout`"
-def setdefaulttimeout(timeout: float | None, /) -> None: ...  # noqa: F811
+def setdefaulttimeout(timeout: float | None, /) -> None: ...
 
 if sys.platform != "win32":
     def sethostname(name: str, /) -> None: ...
@@ -844,4 +800,4 @@ def if_nameindex() -> list[tuple[int, str]]: ...
 def if_nametoindex(oname: str, /) -> int: ...
 def if_indextoname(index: int, /) -> str: ...
 
-CAPI: CapsuleType
+CAPI: object

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_stat.pyi

@@ -0,0 +1,117 @@
+import sys
+from typing import Literal
+
+SF_APPEND: Literal[0x00040000]
+SF_ARCHIVED: Literal[0x00010000]
+SF_IMMUTABLE: Literal[0x00020000]
+SF_NOUNLINK: Literal[0x00100000]
+SF_SNAPSHOT: Literal[0x00200000]
+
+ST_MODE: Literal[0]
+ST_INO: Literal[1]
+ST_DEV: Literal[2]
+ST_NLINK: Literal[3]
+ST_UID: Literal[4]
+ST_GID: Literal[5]
+ST_SIZE: Literal[6]
+ST_ATIME: Literal[7]
+ST_MTIME: Literal[8]
+ST_CTIME: Literal[9]
+
+S_IFIFO: Literal[0o010000]
+S_IFLNK: Literal[0o120000]
+S_IFREG: Literal[0o100000]
+S_IFSOCK: Literal[0o140000]
+S_IFBLK: Literal[0o060000]
+S_IFCHR: Literal[0o020000]
+S_IFDIR: Literal[0o040000]
+
+# These are 0 on systems that don't support the specific kind of file.
+# Example: Linux doesn't support door files, so S_IFDOOR is 0 on linux.
+S_IFDOOR: int
+S_IFPORT: int
+S_IFWHT: int
+
+S_ISUID: Literal[0o4000]
+S_ISGID: Literal[0o2000]
+S_ISVTX: Literal[0o1000]
+
+S_IRWXU: Literal[0o0700]
+S_IRUSR: Literal[0o0400]
+S_IWUSR: Literal[0o0200]
+S_IXUSR: Literal[0o0100]
+
+S_IRWXG: Literal[0o0070]
+S_IRGRP: Literal[0o0040]
+S_IWGRP: Literal[0o0020]
+S_IXGRP: Literal[0o0010]
+
+S_IRWXO: Literal[0o0007]
+S_IROTH: Literal[0o0004]
+S_IWOTH: Literal[0o0002]
+S_IXOTH: Literal[0o0001]
+
+S_ENFMT: Literal[0o2000]
+S_IREAD: Literal[0o0400]
+S_IWRITE: Literal[0o0200]
+S_IEXEC: Literal[0o0100]
+
+UF_APPEND: Literal[0x00000004]
+UF_COMPRESSED: Literal[0x00000020]  # OS X 10.6+ only
+UF_HIDDEN: Literal[0x00008000]  # OX X 10.5+ only
+UF_IMMUTABLE: Literal[0x00000002]
+UF_NODUMP: Literal[0x00000001]
+UF_NOUNLINK: Literal[0x00000010]
+UF_OPAQUE: Literal[0x00000008]
+
+def S_IMODE(mode: int, /) -> int: ...
+def S_IFMT(mode: int, /) -> int: ...
+def S_ISBLK(mode: int, /) -> bool: ...
+def S_ISCHR(mode: int, /) -> bool: ...
+def S_ISDIR(mode: int, /) -> bool: ...
+def S_ISDOOR(mode: int, /) -> bool: ...
+def S_ISFIFO(mode: int, /) -> bool: ...
+def S_ISLNK(mode: int, /) -> bool: ...
+def S_ISPORT(mode: int, /) -> bool: ...
+def S_ISREG(mode: int, /) -> bool: ...
+def S_ISSOCK(mode: int, /) -> bool: ...
+def S_ISWHT(mode: int, /) -> bool: ...
+def filemode(mode: int, /) -> str: ...
+
+if sys.platform == "win32":
+    IO_REPARSE_TAG_SYMLINK: int
+    IO_REPARSE_TAG_MOUNT_POINT: int
+    IO_REPARSE_TAG_APPEXECLINK: int
+
+if sys.platform == "win32":
+    FILE_ATTRIBUTE_ARCHIVE: Literal[32]
+    FILE_ATTRIBUTE_COMPRESSED: Literal[2048]
+    FILE_ATTRIBUTE_DEVICE: Literal[64]
+    FILE_ATTRIBUTE_DIRECTORY: Literal[16]
+    FILE_ATTRIBUTE_ENCRYPTED: Literal[16384]
+    FILE_ATTRIBUTE_HIDDEN: Literal[2]
+    FILE_ATTRIBUTE_INTEGRITY_STREAM: Literal[32768]
+    FILE_ATTRIBUTE_NORMAL: Literal[128]
+    FILE_ATTRIBUTE_NOT_CONTENT_INDEXED: Literal[8192]
+    FILE_ATTRIBUTE_NO_SCRUB_DATA: Literal[131072]
+    FILE_ATTRIBUTE_OFFLINE: Literal[4096]
+    FILE_ATTRIBUTE_READONLY: Literal[1]
+    FILE_ATTRIBUTE_REPARSE_POINT: Literal[1024]
+    FILE_ATTRIBUTE_SPARSE_FILE: Literal[512]
+    FILE_ATTRIBUTE_SYSTEM: Literal[4]
+    FILE_ATTRIBUTE_TEMPORARY: Literal[256]
+    FILE_ATTRIBUTE_VIRTUAL: Literal[65536]
+
+if sys.version_info >= (3, 13):
+    SF_SETTABLE: Literal[0x3FFF0000]
+    # https://github.com/python/cpython/issues/114081#issuecomment-2119017790
+    # SF_RESTRICTED: Literal[0x00080000]
+    SF_FIRMLINK: Literal[0x00800000]
+    SF_DATALESS: Literal[0x40000000]
+
+    SF_SUPPORTED: Literal[0x9F0000]
+    SF_SYNTHETIC: Literal[0xC0000000]
+
+    UF_TRACKED: Literal[0x00000040]
+    UF_DATAVAULT: Literal[0x00000080]
+    UF_SETTABLE: Literal[0x0000FFFF]

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_thread.pyi

@@ -0,0 +1,59 @@
+import sys
+from _typeshed import structseq
+from collections.abc import Callable
+from threading import Thread
+from types import TracebackType
+from typing import Any, Final, NoReturn, final, overload
+from typing_extensions import TypeVarTuple, Unpack
+
+_Ts = TypeVarTuple("_Ts")
+
+error = RuntimeError
+
+def _count() -> int: ...
+@final
+class LockType:
+    def acquire(self, blocking: bool = ..., timeout: float = ...) -> bool: ...
+    def release(self) -> None: ...
+    def locked(self) -> bool: ...
+    def __enter__(self) -> bool: ...
+    def __exit__(
+        self, type: type[BaseException] | None, value: BaseException | None, traceback: TracebackType | None
+    ) -> None: ...
+
+@overload
+def start_new_thread(function: Callable[[Unpack[_Ts]], object], args: tuple[Unpack[_Ts]]) -> int: ...
+@overload
+def start_new_thread(function: Callable[..., object], args: tuple[Any, ...], kwargs: dict[str, Any]) -> int: ...
+def interrupt_main() -> None: ...
+def exit() -> NoReturn: ...
+def allocate_lock() -> LockType: ...
+def get_ident() -> int: ...
+def stack_size(size: int = ...) -> int: ...
+
+TIMEOUT_MAX: float
+
+def get_native_id() -> int: ...  # only available on some platforms
+@final
+class _ExceptHookArgs(structseq[Any], tuple[type[BaseException], BaseException | None, TracebackType | None, Thread | None]):
+    if sys.version_info >= (3, 10):
+        __match_args__: Final = ("exc_type", "exc_value", "exc_traceback", "thread")
+
+    @property
+    def exc_type(self) -> type[BaseException]: ...
+    @property
+    def exc_value(self) -> BaseException | None: ...
+    @property
+    def exc_traceback(self) -> TracebackType | None: ...
+    @property
+    def thread(self) -> Thread | None: ...
+
+_excepthook: Callable[[_ExceptHookArgs], Any]
+
+if sys.version_info >= (3, 12):
+    def daemon_threads_allowed() -> bool: ...
+
+class _local:
+    def __getattribute__(self, name: str, /) -> Any: ...
+    def __setattr__(self, name: str, value: Any, /) -> None: ...
+    def __delattr__(self, name: str, /) -> None: ...

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_threading_local.pyi

@@ -1,6 +1,5 @@
-from threading import RLock
 from typing import Any
-from typing_extensions import Self, TypeAlias
+from typing_extensions import TypeAlias
 from weakref import ReferenceType
 
 __all__ = ["local"]
@@ -9,14 +8,10 @@ _LocalDict: TypeAlias = dict[Any, Any]
 class _localimpl:
     key: str
     dicts: dict[int, tuple[ReferenceType[Any], _LocalDict]]
-    # Keep localargs in sync with the *args, **kwargs annotation on local.__new__
-    localargs: tuple[list[Any], dict[str, Any]]
-    locallock: RLock
     def get_dict(self) -> _LocalDict: ...
     def create_dict(self) -> _LocalDict: ...
 
 class local:
-    def __new__(cls, /, *args: Any, **kw: Any) -> Self: ...
     def __getattribute__(self, name: str) -> Any: ...
     def __setattr__(self, name: str, value: Any) -> None: ...
     def __delattr__(self, name: str) -> None: ...

crates/red_knot_module_resolver/vendor/typeshed/stdlib/_tkinter.pyi

@@ -1,6 +1,6 @@
 import sys
 from collections.abc import Callable
-from typing import Any, ClassVar, Final, final
+from typing import Any, ClassVar, Literal, final
 from typing_extensions import TypeAlias
 
 # _tkinter is meant to be only used internally by tkinter, but some tkinter
@@ -95,49 +95,34 @@ class TkappType:
         def settrace(self, func: _TkinterTraceFunc | None, /) -> None: ...
 
 # These should be kept in sync with tkinter.tix constants, except ALL_EVENTS which doesn't match TCL_ALL_EVENTS
-ALL_EVENTS: Final = -3
-FILE_EVENTS: Final = 8
-IDLE_EVENTS: Final = 32
-TIMER_EVENTS: Final = 16
-WINDOW_EVENTS: Final = 4
+ALL_EVENTS: Literal[-3]
+FILE_EVENTS: Literal[8]
+IDLE_EVENTS: Literal[32]
+TIMER_EVENTS: Literal[16]
+WINDOW_EVENTS: Literal[4]
 
-DONT_WAIT: Final = 2
-EXCEPTION: Final = 8
-READABLE: Final = 2
-WRITABLE: Final = 4
+DONT_WAIT: Literal[2]
+EXCEPTION: Literal[8]
+READABLE: Literal[2]
+WRITABLE: Literal[4]
 
-TCL_VERSION: Final[str]
-TK_VERSION: Final[str]
+TCL_VERSION: str
+TK_VERSION: str
 
 @final
 class TkttType:
     def deletetimerhandler(self): ...
 
-if sys.version_info >= (3, 13):
-    def create(
-        screenName: str | None = None,
-        baseName: str = "",
-        className: str = "Tk",
-        interactive: bool = False,
-        wantobjects: int = 0,
-        wantTk: bool = True,
-        sync: bool = False,
-        use: str | None = None,
-        /,
-    ): ...
-
-else:
-    def create(
-        screenName: str | None = None,
-        baseName: str = "",
-        className: str = "Tk",
-        interactive: bool = False,
-        wantobjects: bool = False,
-        wantTk: bool = True,
-        sync: bool = False,
-        use: str | None = None,
-        /,
-    ): ...
-
+def create(
+    screenName: str | None = None,
+    baseName: str = "",
+    className: str = "Tk",
+    interactive: bool = False,
+    wantobjects: bool = False,
+    wantTk: bool = True,
+    sync: bool = False,
+    use: str | None = None,
+    /,
+): ...
 def getbusywaitinterval(): ...
 def setbusywaitinterval(new_val, /): ...