Bump 0.11.8 (#17766)

## Summary
Contains the same changes to the semantic type inference as
https://github.com/astral-sh/ruff/pull/17705.

Fixes #17694
<!-- What's the purpose of the change? What does it do, and why? -->

## Test Plan

<!-- How was it tested? -->
Snapshot tests.

---------

Co-authored-by: Dhruv Manilawala <dhruvmanila@gmail.com>
Co-authored-by: Brent Westbrook <brentrwestbrook@gmail.com>

.gitattributes

@@ -12,6 +12,12 @@ crates/ruff_python_parser/resources/invalid/re_lexing/line_continuation_windows_
 crates/ruff_python_parser/resources/invalid/re_lex_logical_token_windows_eol.py text eol=crlf
 crates/ruff_python_parser/resources/invalid/re_lex_logical_token_mac_eol.py text eol=cr
 
+crates/ruff_linter/resources/test/fixtures/ruff/RUF046_CR.py text eol=cr
+crates/ruff_linter/resources/test/fixtures/ruff/RUF046_LF.py text eol=lf
+
+crates/ruff_linter/resources/test/fixtures/pyupgrade/UP018_CR.py text eol=cr
+crates/ruff_linter/resources/test/fixtures/pyupgrade/UP018_LF.py text eol=lf
+
 crates/ruff_python_parser/resources/inline linguist-generated=true
 
 ruff.schema.json -diff linguist-generated=true text=auto eol=lf

.github/actionlint.yaml

@@ -6,5 +6,6 @@ self-hosted-runner:
   labels:
     - depot-ubuntu-latest-8
     - depot-ubuntu-22.04-16
+    - depot-ubuntu-22.04-32
     - github-windows-2025-x86_64-8
     - github-windows-2025-x86_64-16

.github/workflows/build-docker.yml

@@ -79,7 +79,7 @@ jobs:
       # Adapted from https://docs.docker.com/build/ci/github-actions/multi-platform/
       - name: Build and push by digest
         id: build
-        uses: docker/build-push-action@471d1dc4e07e5cdedd4c2171150001c434f0b7a4 # v6
+        uses: docker/build-push-action@14487ce63c7a62a4a324b0bfb37086795e31c6c1 # v6
         with:
           context: .
           platforms: ${{ matrix.platform }}
@@ -231,7 +231,7 @@ jobs:
             ${{ env.TAG_PATTERNS }}
 
       - name: Build and push
-        uses: docker/build-push-action@471d1dc4e07e5cdedd4c2171150001c434f0b7a4 # v6
+        uses: docker/build-push-action@14487ce63c7a62a4a324b0bfb37086795e31c6c1 # v6
         with:
           context: .
           platforms: linux/amd64,linux/arm64

.github/workflows/ci.yaml

@@ -239,11 +239,11 @@ jobs:
       - name: "Install mold"
         uses: rui314/setup-mold@e16410e7f8d9e167b74ad5697a9089a35126eb50 # v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@ab3728c7ba6948b9b429627f4d55a68842b27f18 # v2
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@ab3728c7ba6948b9b429627f4d55a68842b27f18 # v2
         with:
           tool: cargo-insta
       - name: Red-knot mdtests (GitHub annotations)
@@ -276,6 +276,10 @@ jobs:
         with:
           name: ruff
           path: target/debug/ruff
+      - uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: red_knot
+          path: target/debug/red_knot
 
   cargo-test-linux-release:
     name: "cargo test (linux, release)"
@@ -293,11 +297,11 @@ jobs:
       - name: "Install mold"
         uses: rui314/setup-mold@e16410e7f8d9e167b74ad5697a9089a35126eb50 # v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@ab3728c7ba6948b9b429627f4d55a68842b27f18 # v2
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@ab3728c7ba6948b9b429627f4d55a68842b27f18 # v2
         with:
           tool: cargo-insta
       - name: "Run tests"
@@ -320,7 +324,7 @@ jobs:
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@ab3728c7ba6948b9b429627f4d55a68842b27f18 # v2
         with:
           tool: cargo-nextest
       - name: "Run tests"
@@ -346,7 +350,7 @@ jobs:
       - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
       - name: "Install Rust toolchain"
         run: rustup target add wasm32-unknown-unknown
-      - uses: actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e # v4.3.0
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 20
           cache: "npm"
@@ -403,11 +407,11 @@ jobs:
       - name: "Install mold"
         uses: rui314/setup-mold@e16410e7f8d9e167b74ad5697a9089a35126eb50 # v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@ab3728c7ba6948b9b429627f4d55a68842b27f18 # v2
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@ab3728c7ba6948b9b429627f4d55a68842b27f18 # v2
         with:
           tool: cargo-insta
       - name: "Run tests"
@@ -632,6 +636,53 @@ jobs:
           name: ecosystem-result
           path: ecosystem-result
 
+  fuzz-redknot:
+    name: "Fuzz for new red-knot panics"
+    runs-on: depot-ubuntu-22.04-16
+    needs:
+      - cargo-test-linux
+      - determine_changes
+    # Only runs on pull requests, since that is the only we way we can find the base version for comparison.
+    if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-test') && github.event_name == 'pull_request' && needs.determine_changes.outputs.red_knot == 'true' }}
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          persist-credentials: false
+      - uses: actions/download-artifact@95815c38cf2ff2164869cbab79da8d1f422bc89e # v4.2.1
+        name: Download new red-knot binary
+        id: redknot-new
+        with:
+          name: red_knot
+          path: target/debug
+      - uses: dawidd6/action-download-artifact@20319c5641d495c8a52e688b7dc5fada6c3a9fbc # v8
+        name: Download baseline red-knot binary
+        with:
+          name: red_knot
+          branch: ${{ github.event.pull_request.base.ref }}
+          workflow: "ci.yaml"
+          check_artifacts: true
+      - uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86 # v5.4.2
+      - name: Fuzz
+        env:
+          FORCE_COLOR: 1
+          NEW_REDKNOT: ${{ steps.redknot-new.outputs.download-path }}
+        run: |
+          # Make executable, since artifact download doesn't preserve this
+          chmod +x "${PWD}/red_knot" "${NEW_REDKNOT}/red_knot"
+
+          (
+            uvx \
+            --python="${PYTHON_VERSION}" \
+            --from=./python/py-fuzzer \
+            fuzz \
+            --test-executable="${NEW_REDKNOT}/red_knot" \
+            --baseline-executable="${PWD}/red_knot" \
+            --only-new-bugs \
+            --bin=red_knot \
+            0-500
+          )
+
   cargo-shear:
     name: "cargo shear"
     runs-on: ubuntu-latest
@@ -821,7 +872,7 @@ jobs:
       - name: "Install Rust toolchain"
         run: rustup target add wasm32-unknown-unknown
       - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
-      - uses: actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e # v4.3.0
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 22
           cache: "npm"
@@ -857,7 +908,7 @@ jobs:
         run: rustup show
 
       - name: "Install codspeed"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@ab3728c7ba6948b9b429627f4d55a68842b27f18 # v2
         with:
           tool: cargo-codspeed
 

.github/workflows/mypy_primer.yaml

@@ -21,11 +21,12 @@ env:
   CARGO_NET_RETRY: 10
   CARGO_TERM_COLOR: always
   RUSTUP_MAX_RETRIES: 10
+  RUST_BACKTRACE: 1
 
 jobs:
   mypy_primer:
     name: Run mypy_primer
-    runs-on: depot-ubuntu-22.04-16
+    runs-on: depot-ubuntu-22.04-32
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
@@ -40,13 +41,10 @@ jobs:
       - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
         with:
           workspaces: "ruff"
+
       - name: Install Rust toolchain
         run: rustup show
 
-      - name: Install mypy_primer
-        run: |
-          uv tool install "git+https://github.com/astral-sh/mypy_primer.git@add-red-knot-support-v5"
-
       - name: Run mypy_primer
         shell: bash
         run: |
@@ -66,7 +64,9 @@ jobs:
 
           echo "Project selector: $PRIMER_SELECTOR"
           # Allow the exit code to be 0 or 1, only fail for actual mypy_primer crashes/bugs
-          uvx mypy_primer \
+          uvx \
+            --from="git+https://github.com/hauntsaninja/mypy_primer@b83b9eade0b7ed2f4b9b129b163acac1ecb48f71" \
+            mypy_primer \
             --repo ruff \
             --type-checker knot \
             --old base_commit \

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

@@ -35,7 +35,7 @@ jobs:
           persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup target add wasm32-unknown-unknown
-      - uses: actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e # v4.3.0
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 22
       - uses: jetli/wasm-bindgen-action@20b33e20595891ab1a0ed73145d8a21fc96e7c29 # v0.2.0

.github/workflows/publish-playground.yml

@@ -29,7 +29,7 @@ jobs:
           persist-credentials: false
       - name: "Install Rust toolchain"
         run: rustup target add wasm32-unknown-unknown
-      - uses: actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e # v4.3.0
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 22
           cache: "npm"

.github/workflows/publish-wasm.yml

@@ -45,7 +45,7 @@ jobs:
           jq '.name="@astral-sh/ruff-wasm-${{ matrix.target }}"' crates/ruff_wasm/pkg/package.json > /tmp/package.json
           mv /tmp/package.json crates/ruff_wasm/pkg
       - run: cp LICENSE crates/ruff_wasm/pkg # wasm-pack does not put the LICENSE file in the pkg
-      - uses: actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e # v4.3.0
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 20
           registry-url: "https://registry.npmjs.org"

.github/workflows/release.yml

@@ -40,6 +40,7 @@ permissions:
 # If there's a prerelease-style suffix to the version, then the release(s)
 # will be marked as a prerelease.
 on:
+  pull_request:
   workflow_dispatch:
     inputs:
       tag:
@@ -60,7 +61,7 @@ jobs:
     env:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     steps:
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      - uses: actions/checkout@85e6279cec87321a52edac9c87bce653a07cf6c2
         with:
           persist-credentials: false
           submodules: recursive
@@ -68,9 +69,9 @@ jobs:
         # we specify bash to get pipefail; it guards against the `curl` command
         # failing. otherwise `sh` won't catch that `curl` returned non-0
         shell: bash
-        run: "curl --proto '=https' --tlsv1.2 -LsSf https://github.com/astral-sh/cargo-dist/releases/download/v0.28.4-prerelease.1/cargo-dist-installer.sh | sh"
+        run: "curl --proto '=https' --tlsv1.2 -LsSf https://github.com/astral-sh/cargo-dist/releases/download/v0.28.4/cargo-dist-installer.sh | sh"
       - name: Cache dist
-        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02
+        uses: actions/upload-artifact@6027e3dd177782cd8ab9af838c04fd81a07f1d47
         with:
           name: cargo-dist-cache
           path: ~/.cargo/bin/dist
@@ -86,7 +87,7 @@ jobs:
           cat plan-dist-manifest.json
           echo "manifest=$(jq -c "." plan-dist-manifest.json)" >> "$GITHUB_OUTPUT"
       - name: "Upload dist-manifest.json"
-        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02
+        uses: actions/upload-artifact@6027e3dd177782cd8ab9af838c04fd81a07f1d47
         with:
           name: artifacts-plan-dist-manifest
           path: plan-dist-manifest.json
@@ -123,19 +124,19 @@ jobs:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       BUILD_MANIFEST_NAME: target/distrib/global-dist-manifest.json
     steps:
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      - uses: actions/checkout@85e6279cec87321a52edac9c87bce653a07cf6c2
         with:
           persist-credentials: false
           submodules: recursive
       - name: Install cached dist
-        uses: actions/download-artifact@95815c38cf2ff2164869cbab79da8d1f422bc89e
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093
         with:
           name: cargo-dist-cache
           path: ~/.cargo/bin/
       - run: chmod +x ~/.cargo/bin/dist
       # Get all the local artifacts for the global tasks to use (for e.g. checksums)
       - name: Fetch local artifacts
-        uses: actions/download-artifact@95815c38cf2ff2164869cbab79da8d1f422bc89e
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093
         with:
           pattern: artifacts-*
           path: target/distrib/
@@ -153,7 +154,7 @@ jobs:
 
           cp dist-manifest.json "$BUILD_MANIFEST_NAME"
       - name: "Upload artifacts"
-        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02
+        uses: actions/upload-artifact@6027e3dd177782cd8ab9af838c04fd81a07f1d47
         with:
           name: artifacts-build-global
           path: |
@@ -174,19 +175,19 @@ jobs:
     outputs:
       val: ${{ steps.host.outputs.manifest }}
     steps:
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      - uses: actions/checkout@85e6279cec87321a52edac9c87bce653a07cf6c2
         with:
           persist-credentials: false
           submodules: recursive
       - name: Install cached dist
-        uses: actions/download-artifact@95815c38cf2ff2164869cbab79da8d1f422bc89e
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093
         with:
           name: cargo-dist-cache
           path: ~/.cargo/bin/
       - run: chmod +x ~/.cargo/bin/dist
       # Fetch artifacts from scratch-storage
       - name: Fetch artifacts
-        uses: actions/download-artifact@95815c38cf2ff2164869cbab79da8d1f422bc89e
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093
         with:
           pattern: artifacts-*
           path: target/distrib/
@@ -200,7 +201,7 @@ jobs:
           cat dist-manifest.json
           echo "manifest=$(jq -c "." dist-manifest.json)" >> "$GITHUB_OUTPUT"
       - name: "Upload dist-manifest.json"
-        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02
+        uses: actions/upload-artifact@6027e3dd177782cd8ab9af838c04fd81a07f1d47
         with:
           # Overwrite the previous copy
           name: artifacts-dist-manifest
@@ -250,13 +251,13 @@ jobs:
     env:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     steps:
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      - uses: actions/checkout@85e6279cec87321a52edac9c87bce653a07cf6c2
         with:
           persist-credentials: false
           submodules: recursive
       # Create a GitHub Release while uploading all files to it
       - name: "Download GitHub Artifacts"
-        uses: actions/download-artifact@95815c38cf2ff2164869cbab79da8d1f422bc89e
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093
         with:
           pattern: artifacts-*
           path: artifacts

.pre-commit-config.yaml

@@ -79,7 +79,7 @@ repos:
         pass_filenames: false # This makes it a lot faster
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.11.6
+    rev: v0.11.7
     hooks:
       - id: ruff-format
       - id: ruff

CHANGELOG.md

@@ -1,5 +1,66 @@
 # Changelog
 
+## 0.11.8
+
+### Preview features
+
+- \[`airflow`\] Apply auto fixes to cases where the names have changed in Airflow 3 (`AIR302`, `AIR311`) ([#17553](https://github.com/astral-sh/ruff/pull/17553), [#17570](https://github.com/astral-sh/ruff/pull/17570), [#17571](https://github.com/astral-sh/ruff/pull/17571))
+- \[`airflow`\] Extend `AIR301` rule ([#17598](https://github.com/astral-sh/ruff/pull/17598))
+- \[`airflow`\] Update existing `AIR302` rules with better suggestions ([#17542](https://github.com/astral-sh/ruff/pull/17542))
+- \[`refurb`\] Mark fix as safe for `readlines-in-for` (`FURB129`) ([#17644](https://github.com/astral-sh/ruff/pull/17644))
+- [syntax-errors] `nonlocal` declaration at module level ([#17559](https://github.com/astral-sh/ruff/pull/17559))
+- [syntax-errors] Detect single starred expression assignment `x = *y` ([#17624](https://github.com/astral-sh/ruff/pull/17624))
+
+### Bug fixes
+
+- \[`flake8-pyi`\] Ensure `Literal[None,] | Literal[None,]` is not autofixed to `None | None` (`PYI061`) ([#17659](https://github.com/astral-sh/ruff/pull/17659))
+- \[`flake8-use-pathlib`\] Avoid suggesting `Path.iterdir()` for `os.listdir` with file descriptor (`PTH208`) ([#17715](https://github.com/astral-sh/ruff/pull/17715))
+- \[`flake8-use-pathlib`\] Fix `PTH104` false positive when `rename` is passed a file descriptor ([#17712](https://github.com/astral-sh/ruff/pull/17712))
+- \[`flake8-use-pathlib`\] Fix `PTH116` false positive when `stat` is passed a file descriptor ([#17709](https://github.com/astral-sh/ruff/pull/17709))
+- \[`flake8-use-pathlib`\] Fix `PTH123` false positive when `open` is passed a file descriptor from a function call ([#17705](https://github.com/astral-sh/ruff/pull/17705))
+- \[`pycodestyle`\] Fix duplicated diagnostic in `E712` ([#17651](https://github.com/astral-sh/ruff/pull/17651))
+- \[`pylint`\] Detect `global` declarations in module scope (`PLE0118`) ([#17411](https://github.com/astral-sh/ruff/pull/17411))
+- [syntax-errors] Make `async-comprehension-in-sync-comprehension` more specific ([#17460](https://github.com/astral-sh/ruff/pull/17460))
+
+### Configuration
+
+- Add option to disable `typing_extensions` imports ([#17611](https://github.com/astral-sh/ruff/pull/17611))
+
+### Documentation
+
+- Fix example syntax for the `lint.pydocstyle.ignore-var-parameters` option ([#17740](https://github.com/astral-sh/ruff/pull/17740))
+- Add fix safety sections (`ASYNC116`, `FLY002`, `D200`, `RUF005`, `RUF017`, `RUF027`, `RUF028`, `RUF057`) ([#17497](https://github.com/astral-sh/ruff/pull/17497), [#17496](https://github.com/astral-sh/ruff/pull/17496), [#17502](https://github.com/astral-sh/ruff/pull/17502), [#17484](https://github.com/astral-sh/ruff/pull/17484), [#17480](https://github.com/astral-sh/ruff/pull/17480), [#17485](https://github.com/astral-sh/ruff/pull/17485), [#17722](https://github.com/astral-sh/ruff/pull/17722), [#17483](https://github.com/astral-sh/ruff/pull/17483))
+
+### Other changes
+
+- Add Python 3.14 to configuration options ([#17647](https://github.com/astral-sh/ruff/pull/17647))
+- Make syntax error for unparenthesized except tuples version specific to before 3.14 ([#17660](https://github.com/astral-sh/ruff/pull/17660))
+
+## 0.11.7
+
+### Preview features
+
+- \[`airflow`\] Apply auto fixes to cases where the names have changed in Airflow 3 (`AIR301`) ([#17355](https://github.com/astral-sh/ruff/pull/17355))
+- \[`perflint`\] Implement fix for `manual-dict-comprehension` (`PERF403`) ([#16719](https://github.com/astral-sh/ruff/pull/16719))
+- [syntax-errors] Make duplicate parameter names a semantic error ([#17131](https://github.com/astral-sh/ruff/pull/17131))
+
+### Bug fixes
+
+- \[`airflow`\] Fix typos in provider package names (`AIR302`, `AIR312`) ([#17574](https://github.com/astral-sh/ruff/pull/17574))
+- \[`flake8-type-checking`\] Visit keyword arguments in checks involving `typing.cast`/`typing.NewType` arguments ([#17538](https://github.com/astral-sh/ruff/pull/17538))
+- \[`pyupgrade`\] Preserve parenthesis when fixing native literals containing newlines (`UP018`) ([#17220](https://github.com/astral-sh/ruff/pull/17220))
+- \[`refurb`\] Mark the `FURB161` fix unsafe except for integers and booleans ([#17240](https://github.com/astral-sh/ruff/pull/17240))
+
+### Rule changes
+
+- \[`perflint`\] Allow list function calls to be replaced with a comprehension (`PERF401`) ([#17519](https://github.com/astral-sh/ruff/pull/17519))
+- \[`pycodestyle`\] Auto-fix redundant boolean comparison (`E712`) ([#17090](https://github.com/astral-sh/ruff/pull/17090))
+- \[`pylint`\] make fix unsafe if delete comments (`PLR1730`) ([#17459](https://github.com/astral-sh/ruff/pull/17459))
+
+### Documentation
+
+- Add fix safety sections to docs for several rules ([#17410](https://github.com/astral-sh/ruff/pull/17410),[#17440](https://github.com/astral-sh/ruff/pull/17440),[#17441](https://github.com/astral-sh/ruff/pull/17441),[#17443](https://github.com/astral-sh/ruff/pull/17443),[#17444](https://github.com/astral-sh/ruff/pull/17444))
+
 ## 0.11.6
 
 ### Preview features

Cargo.lock

@@ -394,7 +394,7 @@ dependencies = [
  "heck",
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -490,20 +490,6 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
-[[package]]
-name = "compact_str"
-version = "0.8.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b79c4069c6cad78e2e0cdfcbd26275770669fb39fd308a752dc110e83b9af32"
-dependencies = [
- "castaway",
- "cfg-if",
- "itoa",
- "rustversion",
- "ryu",
- "static_assertions",
-]
-
 [[package]]
 name = "compact_str"
 version = "0.9.0"
@@ -724,7 +710,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "strsim",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -735,7 +721,7 @@ checksum = "d336a2a514f6ccccaa3e09b02d41d35330c07ddf03a62165fcec10bb561c7806"
 dependencies = [
  "darling_core",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -805,7 +791,7 @@ dependencies = [
  "glob",
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -837,7 +823,7 @@ checksum = "97369cbbc041bc366949bc74d34658d6cda5621039731c6310521892a3a20ae0"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -1323,7 +1309,7 @@ checksum = "1ec89e9337638ecdc08744df490b221a7399bf8d164eb52a665454e60e075ad6"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -1488,7 +1474,7 @@ dependencies = [
  "heck",
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -1553,9 +1539,9 @@ checksum = "4a5f13b858c8d314ee3e8f639011f7ccefe71f97f96e50151fb991f267928e2c"
 
 [[package]]
 name = "jiff"
-version = "0.2.9"
+version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "59ec30f7142be6fe14e1b021f50b85db8df2d4324ea6e91ec3e5dcde092021d0"
+checksum = "5a064218214dc6a10fbae5ec5fa888d80c45d611aba169222fc272072bf7aef6"
 dependencies = [
  "jiff-static",
  "jiff-tzdb-platform",
@@ -1563,18 +1549,18 @@ dependencies = [
  "portable-atomic",
  "portable-atomic-util",
  "serde",
- "windows-sys 0.59.0",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
 name = "jiff-static"
-version = "0.2.9"
+version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "526b834d727fd59d37b076b0c3236d9adde1b1729a4361e20b2026f738cc1dbe"
+checksum = "199b7932d97e325aff3a7030e141eafe7f2c6268e1d1b24859b753a627f45254"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -1671,7 +1657,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bfa96ed35d0dccc67cf7ba49350cb86de3dcb1d072a7ab28f99117f19d874953"
 dependencies = [
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -2180,7 +2166,7 @@ dependencies = [
  "pest_meta",
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -2249,7 +2235,7 @@ checksum = "6e918e4ff8c4549eb882f14b3a4bc8c8bc93de829416eacf579f1207a8fbf861"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -2572,7 +2558,7 @@ dependencies = [
  "anyhow",
  "bitflags 2.9.0",
  "camino",
- "compact_str 0.9.0",
+ "compact_str",
  "countme",
  "dir-test",
  "drop_bomb",
@@ -2772,7 +2758,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.11.6"
+version = "0.11.8"
 dependencies = [
  "anyhow",
  "argfile",
@@ -2879,6 +2865,7 @@ dependencies = [
 name = "ruff_db"
 version = "0.0.0"
 dependencies = [
+ "anstyle",
  "camino",
  "countme",
  "dashmap 6.1.0",
@@ -3007,7 +2994,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_linter"
-version = "0.11.6"
+version = "0.11.8"
 dependencies = [
  "aho-corasick",
  "anyhow",
@@ -3074,7 +3061,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "ruff_python_trivia",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -3101,7 +3088,7 @@ version = "0.0.0"
 dependencies = [
  "aho-corasick",
  "bitflags 2.9.0",
- "compact_str 0.9.0",
+ "compact_str",
  "is-macro",
  "itertools 0.14.0",
  "memchr",
@@ -3199,7 +3186,7 @@ dependencies = [
  "anyhow",
  "bitflags 2.9.0",
  "bstr",
- "compact_str 0.9.0",
+ "compact_str",
  "insta",
  "memchr",
  "ruff_annotate_snippets",
@@ -3333,7 +3320,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_wasm"
-version = "0.11.6"
+version = "0.11.8"
 dependencies = [
  "console_error_panic_hook",
  "console_log",
@@ -3457,11 +3444,11 @@ checksum = "28d3b2b1366ec20994f1fd18c3c594f05c5dd4bc44d8bb0c1c632c8d6829481f"
 
 [[package]]
 name = "salsa"
-version = "0.19.0"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=87bf6b6c2d5f6479741271da73bd9d30c2580c26#87bf6b6c2d5f6479741271da73bd9d30c2580c26"
+version = "0.21.0"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=42f15835c0005c4b37aaf5bc1a15e3e1b3df14b7#42f15835c0005c4b37aaf5bc1a15e3e1b3df14b7"
 dependencies = [
  "boxcar",
- "compact_str 0.8.1",
+ "compact_str",
  "crossbeam-queue",
  "dashmap 6.1.0",
  "hashbrown 0.15.2",
@@ -3480,18 +3467,18 @@ dependencies = [
 
 [[package]]
 name = "salsa-macro-rules"
-version = "0.19.0"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=87bf6b6c2d5f6479741271da73bd9d30c2580c26#87bf6b6c2d5f6479741271da73bd9d30c2580c26"
+version = "0.21.0"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=42f15835c0005c4b37aaf5bc1a15e3e1b3df14b7#42f15835c0005c4b37aaf5bc1a15e3e1b3df14b7"
 
 [[package]]
 name = "salsa-macros"
-version = "0.19.0"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=87bf6b6c2d5f6479741271da73bd9d30c2580c26#87bf6b6c2d5f6479741271da73bd9d30c2580c26"
+version = "0.21.0"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=42f15835c0005c4b37aaf5bc1a15e3e1b3df14b7#42f15835c0005c4b37aaf5bc1a15e3e1b3df14b7"
 dependencies = [
  "heck",
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
  "synstructure",
 ]
 
@@ -3525,7 +3512,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "serde_derive_internals",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -3574,7 +3561,7 @@ checksum = "5b0276cf7f2c73365f7157c8123c21cd9a50fbbd844757af28ca1f5925fc2a00"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -3585,7 +3572,7 @@ checksum = "18d26a20a969b9e3fdf2fc2d9f21eda6c40e2de84c9408bb5d3b05d499aae711"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -3608,7 +3595,7 @@ checksum = "175ee3e80ae9982737ca543e96133087cbd9a485eecc3bc4de9c1a37b47ea59c"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -3649,7 +3636,7 @@ dependencies = [
  "darling",
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -3780,7 +3767,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "rustversion",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -3796,9 +3783,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.100"
+version = "2.0.101"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b09a44accad81e1ba1cd74a32461ba89dee89095ba17b32f5d03683b1b1fc2a0"
+checksum = "8ce2b7fc941b3a24138a0a7cf8e858bfc6a992e7978a068a5c760deb0ed43caf"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -3813,7 +3800,7 @@ checksum = "c8af7666ab7b6390ab78131fb5b0fce11d6b7a6951602017c35fa82800708971"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -3884,7 +3871,7 @@ dependencies = [
  "cfg-if",
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -3895,7 +3882,7 @@ checksum = "5c89e72a01ed4c579669add59014b9a524d609c0c88c6a585ce37485879f6ffb"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
  "test-case-core",
 ]
 
@@ -3931,7 +3918,7 @@ checksum = "4fee6c4efc90059e10f81e6d42c60a18f76588c3d74cb83a0b242a2b6c7504c1"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -3942,7 +3929,7 @@ checksum = "7f7cf42b4507d8ea322120659672cf1b9dbb93f8f2d4ecfd6e51350ff5b17a1d"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -4073,7 +4060,7 @@ checksum = "395ae124c09f9e6918a2310af6038fba074bcf474ac352496d5910dd59a2226d"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -4340,7 +4327,7 @@ checksum = "72dcd78c4f979627a754f5522cea6e6a25e55139056535fe6e69c506cd64a862"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -4462,7 +4449,7 @@ dependencies = [
  "log",
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
  "wasm-bindgen-shared",
 ]
 
@@ -4497,7 +4484,7 @@ checksum = "8ae87ea40c9f689fc23f209965b6fb8a99ad69aeeb0231408be24920604395de"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
  "wasm-bindgen-backend",
  "wasm-bindgen-shared",
 ]
@@ -4532,7 +4519,7 @@ checksum = "17d5042cc5fa009658f9a7333ef24291b1291a25b6382dd68862a7f3b969f69b"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -4647,7 +4634,7 @@ checksum = "2bbd5b46c938e506ecbce286b6628a02171d56153ba733b6c741fc627ec9579b"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -4658,7 +4645,7 @@ checksum = "053c4c462dc91d3b1504c6fe5a726dd15e216ba718e84a0e46a88fbe5ded3515"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -4896,7 +4883,7 @@ checksum = "2380878cad4ac9aac1e2435f3eb4020e8374b5f13c296cb75b4620ff8e229154"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
  "synstructure",
 ]
 
@@ -4917,7 +4904,7 @@ checksum = "6352c01d0edd5db859a63e2605f4ea3183ddbd15e2c4a9e7d32184df75e4f154"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]
@@ -4937,7 +4924,7 @@ checksum = "d71e5d6e06ab090c67b5e44993ec16b72dcbaabc526db883a360057678b48502"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
  "synstructure",
 ]
 
@@ -4960,7 +4947,7 @@ checksum = "6eafa6dfb17584ea3e2bd6e76e0cc15ad7af12b09abdd1ca55961bed9b1063c6"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.100",
+ "syn 2.0.101",
 ]
 
 [[package]]

Cargo.toml

@@ -124,7 +124,7 @@ rayon = { version = "1.10.0" }
 regex = { version = "1.10.2" }
 rustc-hash = { version = "2.0.0" }
 # When updating salsa, make sure to also update the revision in `fuzz/Cargo.toml`
-salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "87bf6b6c2d5f6479741271da73bd9d30c2580c26" }
+salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "42f15835c0005c4b37aaf5bc1a15e3e1b3df14b7" }
 schemars = { version = "0.8.16" }
 seahash = { version = "4.1.0" }
 serde = { version = "1.0.197", features = ["derive"] }
@@ -272,7 +272,9 @@ inherits = "release"
 # Config for 'dist'
 [workspace.metadata.dist]
 # The preferred dist version to use in CI (Cargo.toml SemVer syntax)
-cargo-dist-version = "0.28.4-prerelease.1"
+cargo-dist-version = "0.28.4"
+# Make distability of apps opt-in instead of opt-out
+dist = false
 # CI backends to support
 ci = "github"
 # The installers to generate for each app
@@ -306,7 +308,7 @@ auto-includes = false
 # Whether dist should create a Github Release or use an existing draft
 create-release = true
 # Which actions to run on pull requests
-pr-run-mode = "skip"
+pr-run-mode = "plan"
 # Whether CI should trigger releases with dispatches instead of tag pushes
 dispatch-releases = true
 # Which phase dist should use to create the GitHub release
@@ -334,7 +336,7 @@ install-path = ["$XDG_BIN_HOME/", "$XDG_DATA_HOME/../bin", "~/.local/bin"]
 global = "depot-ubuntu-latest-4"
 
 [workspace.metadata.dist.github-action-commits]
-"actions/checkout" = "11bd71901bbe5b1630ceea73d27597364c9af683" # v4
-"actions/upload-artifact" = "ea165f8d65b6e75b540449e92b4886f43607fa02" # v4.6.2
-"actions/download-artifact" = "95815c38cf2ff2164869cbab79da8d1f422bc89e" # v4.2.1
+"actions/checkout" = "85e6279cec87321a52edac9c87bce653a07cf6c2" # v4
+"actions/upload-artifact" = "6027e3dd177782cd8ab9af838c04fd81a07f1d47" # v4.6.2
+"actions/download-artifact" = "d3f86a106a0bac45b974a628896c90dbdf5c8093" # v4.3.0
 "actions/attest-build-provenance" = "c074443f1aee8d4aeeae555aebba3282517141b2" #v2.2.3

README.md

@@ -149,8 +149,8 @@ curl -LsSf https://astral.sh/ruff/install.sh | sh
 powershell -c "irm https://astral.sh/ruff/install.ps1 | iex"
 
 # For a specific version.
-curl -LsSf https://astral.sh/ruff/0.11.6/install.sh | sh
-powershell -c "irm https://astral.sh/ruff/0.11.6/install.ps1 | iex"
+curl -LsSf https://astral.sh/ruff/0.11.8/install.sh | sh
+powershell -c "irm https://astral.sh/ruff/0.11.8/install.ps1 | iex"
 ```
 
 You can also install Ruff via [Homebrew](https://formulae.brew.sh/formula/ruff), [Conda](https://anaconda.org/conda-forge/ruff),
@@ -183,7 +183,7 @@ Ruff can also be used as a [pre-commit](https://pre-commit.com/) hook via [`ruff
 ```yaml
 - repo: https://github.com/astral-sh/ruff-pre-commit
   # Ruff version.
-  rev: v0.11.6
+  rev: v0.11.8
   hooks:
     # Run the linter.
     - id: ruff

crates/red_knot/docs/mypy_primer.md

@@ -2,16 +2,16 @@
 
 ## Basics
 
-For now, we use our own [fork of mypy primer]. It can be run using `uvx --from "…" mypy_primer`. For example, to see the help message, run:
+`mypy_primer` can be run using `uvx --from "…" mypy_primer`. For example, to see the help message, run:
 
 ```sh
-uvx --from "git+https://github.com/astral-sh/mypy_primer.git@add-red-knot-support" mypy_primer -h
+uvx --from "git+https://github.com/hauntsaninja/mypy_primer" mypy_primer -h
 ```
 
 Alternatively, you can install the forked version of `mypy_primer` using:
 
 ```sh
-uv tool install "git+https://github.com/astral-sh/mypy_primer.git@add-red-knot-support"
+uv tool install "git+https://github.com/hauntsaninja/mypy_primer"
 ```
 
 and then run it using `uvx mypy_primer` or just `mypy_primer`, if your `PATH` is set up accordingly (see: [Tool executables]).
@@ -56,6 +56,5 @@ mypy_primer --repo /path/to/ruff --old origin/main --new my/local-branch …
 
 Note that you might need to clean up `/tmp/mypy_primer` in order for this to work correctly.
 
-[fork of mypy primer]: https://github.com/astral-sh/mypy_primer/tree/add-red-knot-support
-[full list of ecosystem projects]: https://github.com/astral-sh/mypy_primer/blob/add-red-knot-support/mypy_primer/projects.py
+[full list of ecosystem projects]: https://github.com/hauntsaninja/mypy_primer/blob/master/mypy_primer/projects.py
 [tool executables]: https://docs.astral.sh/uv/concepts/tools/#tool-executables

crates/red_knot/src/args.rs

@@ -105,6 +105,19 @@ pub(crate) struct CheckCommand {
     /// Watch files for changes and recheck files related to the changed files.
     #[arg(long, short = 'W')]
     pub(crate) watch: bool,
+
+    /// Respect file exclusions via `.gitignore` and other standard ignore files.
+    /// Use `--no-respect-gitignore` to disable.
+    #[arg(
+        long,
+        overrides_with("no_respect_ignore_files"),
+        help_heading = "File selection",
+        default_missing_value = "true",
+        num_args = 0..1
+    )]
+    respect_ignore_files: Option<bool>,
+    #[clap(long, overrides_with("respect_ignore_files"), hide = true)]
+    no_respect_ignore_files: bool,
 }
 
 impl CheckCommand {
@@ -120,6 +133,13 @@ impl CheckCommand {
             )
         };
 
+        // --no-respect-gitignore defaults to false and is set true by CLI flag. If passed, override config file
+        // Otherwise, only pass this through if explicitly set (don't default to anything here to
+        // make sure that doesn't take precedence over an explicitly-set config file value)
+        let respect_ignore_files = self
+            .no_respect_ignore_files
+            .then_some(false)
+            .or(self.respect_ignore_files);
         Options {
             environment: Some(EnvironmentOptions {
                 python_version: self
@@ -144,6 +164,7 @@ impl CheckCommand {
                 error_on_warning: self.error_on_warning,
             }),
             rules,
+            respect_ignore_files,
             ..Default::default()
         }
     }

crates/red_knot/src/main.rs

@@ -169,8 +169,12 @@ pub enum ExitStatus {
     /// Checking was successful but there were errors.
     Failure = 1,
 
-    /// Checking failed.
+    /// Checking failed due to an invocation error (e.g. the current directory no longer exists, incorrect CLI arguments, ...)
     Error = 2,
+
+    /// Internal Red Knot error (panic, or any other error that isn't due to the user using the
+    /// program incorrectly or transient environment errors).
+    InternalError = 101,
 }
 
 impl Termination for ExitStatus {
@@ -246,11 +250,16 @@ impl MainLoop {
                     // Spawn a new task that checks the project. 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.
-                            sender
-                                .send(MainLoopMessage::CheckCompleted { result, revision })
-                                .unwrap();
+                        match db.check() {
+                            Ok(result) => {
+                                // Send the result back to the main loop for printing.
+                                sender
+                                    .send(MainLoopMessage::CheckCompleted { result, revision })
+                                    .unwrap();
+                            }
+                            Err(cancelled) => {
+                                tracing::debug!("Check has been cancelled: {cancelled:?}");
+                            }
                         }
                     });
                 }
@@ -264,12 +273,6 @@ impl MainLoop {
                         .format(terminal_settings.output_format)
                         .color(colored::control::SHOULD_COLORIZE.should_colorize());
 
-                    let min_error_severity = if terminal_settings.error_on_warning {
-                        Severity::Warning
-                    } else {
-                        Severity::Error
-                    };
-
                     if check_revision == revision {
                         if db.project().files(db).is_empty() {
                             tracing::warn!("No python files found under the given path(s)");
@@ -284,13 +287,13 @@ impl MainLoop {
                                 return Ok(ExitStatus::Success);
                             }
                         } else {
-                            let mut failed = false;
+                            let mut max_severity = Severity::Info;
                             let diagnostics_count = result.len();
 
                             for diagnostic in result {
                                 write!(stdout, "{}", diagnostic.display(db, &display_config))?;
 
-                                failed |= diagnostic.severity() >= min_error_severity;
+                                max_severity = max_severity.max(diagnostic.severity());
                             }
 
                             writeln!(
@@ -301,10 +304,17 @@ impl MainLoop {
                             )?;
 
                             if self.watcher.is_none() {
-                                return Ok(if failed {
-                                    ExitStatus::Failure
-                                } else {
-                                    ExitStatus::Success
+                                return Ok(match max_severity {
+                                    Severity::Info => ExitStatus::Success,
+                                    Severity::Warning => {
+                                        if terminal_settings.error_on_warning {
+                                            ExitStatus::Failure
+                                        } else {
+                                            ExitStatus::Success
+                                        }
+                                    }
+                                    Severity::Error => ExitStatus::Failure,
+                                    Severity::Fatal => ExitStatus::InternalError,
                                 });
                             }
                         }

crates/red_knot/tests/cli.rs

@@ -5,6 +5,116 @@ use std::path::{Path, PathBuf};
 use std::process::Command;
 use tempfile::TempDir;
 
+#[test]
+fn test_run_in_sub_directory() -> anyhow::Result<()> {
+    let case = TestCase::with_files([("test.py", "~"), ("subdir/nothing", "")])?;
+    assert_cmd_snapshot!(case.command().current_dir(case.root().join("subdir")).arg(".."), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    error: invalid-syntax
+     --> <temp_dir>/test.py:1:2
+      |
+    1 | ~
+      |  ^ Expected an expression
+      |
+
+    Found 1 diagnostic
+
+    ----- stderr -----
+    ");
+    Ok(())
+}
+
+#[test]
+fn test_include_hidden_files_by_default() -> anyhow::Result<()> {
+    let case = TestCase::with_files([(".test.py", "~")])?;
+    assert_cmd_snapshot!(case.command(), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    error: invalid-syntax
+     --> .test.py:1:2
+      |
+    1 | ~
+      |  ^ Expected an expression
+      |
+
+    Found 1 diagnostic
+
+    ----- stderr -----
+    ");
+    Ok(())
+}
+
+#[test]
+fn test_respect_ignore_files() -> anyhow::Result<()> {
+    // First test that the default option works correctly (the file is skipped)
+    let case = TestCase::with_files([(".ignore", "test.py"), ("test.py", "~")])?;
+    assert_cmd_snapshot!(case.command(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    All checks passed!
+
+    ----- stderr -----
+    WARN No python files found under the given path(s)
+    ");
+
+    // Test that we can set to false via CLI
+    assert_cmd_snapshot!(case.command().arg("--no-respect-ignore-files"), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    error: invalid-syntax
+     --> test.py:1:2
+      |
+    1 | ~
+      |  ^ Expected an expression
+      |
+
+    Found 1 diagnostic
+
+    ----- stderr -----
+    ");
+
+    // Test that we can set to false via config file
+    case.write_file("knot.toml", "respect-ignore-files = false")?;
+    assert_cmd_snapshot!(case.command(), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    error: invalid-syntax
+     --> test.py:1:2
+      |
+    1 | ~
+      |  ^ Expected an expression
+      |
+
+    Found 1 diagnostic
+
+    ----- stderr -----
+    ");
+
+    // Ensure CLI takes precedence
+    case.write_file("knot.toml", "respect-ignore-files = true")?;
+    assert_cmd_snapshot!(case.command().arg("--no-respect-ignore-files"), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    error: invalid-syntax
+     --> test.py:1:2
+      |
+    1 | ~
+      |  ^ Expected an expression
+      |
+
+    Found 1 diagnostic
+
+    ----- stderr -----
+    ");
+    Ok(())
+}
 /// Specifying an option on the CLI should take precedence over the same setting in the
 /// project's configuration. Here, this is tested for the Python version.
 #[test]
@@ -32,12 +142,12 @@ fn config_override_python_version() -> anyhow::Result<()> {
     success: false
     exit_code: 1
     ----- stdout -----
-    error: lint:unresolved-attribute
-     --> <temp_dir>/test.py:5:7
+    error: lint:unresolved-attribute: Type `<module 'sys'>` has no attribute `last_exc`
+     --> test.py:5:7
       |
     4 | # Access `sys.last_exc` that was only added in Python 3.12
     5 | print(sys.last_exc)
-      |       ^^^^^^^^^^^^ Type `<module 'sys'>` has no attribute `last_exc`
+      |       ^^^^^^^^^^^^
       |
 
     Found 1 diagnostic
@@ -84,7 +194,7 @@ fn config_override_python_platform() -> anyhow::Result<()> {
     exit_code: 0
     ----- stdout -----
     info: revealed-type: Revealed type
-     --> <temp_dir>/test.py:5:1
+     --> test.py:5:1
       |
     3 | from typing_extensions import reveal_type
     4 |
@@ -102,7 +212,7 @@ fn config_override_python_platform() -> anyhow::Result<()> {
     exit_code: 0
     ----- stdout -----
     info: revealed-type: Revealed type
-     --> <temp_dir>/test.py:5:1
+     --> test.py:5:1
       |
     3 | from typing_extensions import reveal_type
     4 |
@@ -165,11 +275,11 @@ fn cli_arguments_are_relative_to_the_current_directory() -> anyhow::Result<()> {
     success: false
     exit_code: 1
     ----- stdout -----
-    error: lint:unresolved-import
-     --> <temp_dir>/child/test.py:2:6
+    error: lint:unresolved-import: Cannot resolve import `utils`
+     --> test.py:2:6
       |
     2 | from utils import add
-      |      ^^^^^ Cannot resolve import `utils`
+      |      ^^^^^
     3 |
     4 | stat = add(10, 15)
       |
@@ -265,22 +375,22 @@ fn configuration_rule_severity() -> anyhow::Result<()> {
     success: false
     exit_code: 1
     ----- stdout -----
-    error: lint:division-by-zero
-     --> <temp_dir>/test.py:2:5
+    error: lint:division-by-zero: Cannot divide object of type `Literal[4]` by zero
+     --> test.py:2:5
       |
     2 | y = 4 / 0
-      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^
     3 |
     4 | for a in range(0, int(y)):
       |
 
-    warning: lint:possibly-unresolved-reference
-     --> <temp_dir>/test.py:7:7
+    warning: lint:possibly-unresolved-reference: Name `x` used when possibly not defined
+     --> test.py:7:7
       |
     5 |     x = a
     6 |
     7 | print(x)  # possibly-unresolved-reference
-      |       ^ Name `x` used when possibly not defined
+      |       ^
       |
 
     Found 2 diagnostics
@@ -301,11 +411,11 @@ fn configuration_rule_severity() -> anyhow::Result<()> {
     success: true
     exit_code: 0
     ----- stdout -----
-    warning: lint:division-by-zero
-     --> <temp_dir>/test.py:2:5
+    warning: lint:division-by-zero: Cannot divide object of type `Literal[4]` by zero
+     --> test.py:2:5
       |
     2 | y = 4 / 0
-      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^
     3 |
     4 | for a in range(0, int(y)):
       |
@@ -341,33 +451,33 @@ fn cli_rule_severity() -> anyhow::Result<()> {
     success: false
     exit_code: 1
     ----- stdout -----
-    error: lint:unresolved-import
-     --> <temp_dir>/test.py:2:8
+    error: lint:unresolved-import: Cannot resolve import `does_not_exit`
+     --> test.py:2:8
       |
     2 | import does_not_exit
-      |        ^^^^^^^^^^^^^ Cannot resolve import `does_not_exit`
+      |        ^^^^^^^^^^^^^
     3 |
     4 | y = 4 / 0
       |
 
-    error: lint:division-by-zero
-     --> <temp_dir>/test.py:4:5
+    error: lint:division-by-zero: Cannot divide object of type `Literal[4]` by zero
+     --> test.py:4:5
       |
     2 | import does_not_exit
     3 |
     4 | y = 4 / 0
-      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^
     5 |
     6 | for a in range(0, int(y)):
       |
 
-    warning: lint:possibly-unresolved-reference
-     --> <temp_dir>/test.py:9:7
+    warning: lint:possibly-unresolved-reference: Name `x` used when possibly not defined
+     --> test.py:9:7
       |
     7 |     x = a
     8 |
     9 | print(x)  # possibly-unresolved-reference
-      |       ^ Name `x` used when possibly not defined
+      |       ^
       |
 
     Found 3 diagnostics
@@ -388,22 +498,22 @@ fn cli_rule_severity() -> anyhow::Result<()> {
     success: true
     exit_code: 0
     ----- stdout -----
-    warning: lint:unresolved-import
-     --> <temp_dir>/test.py:2:8
+    warning: lint:unresolved-import: Cannot resolve import `does_not_exit`
+     --> test.py:2:8
       |
     2 | import does_not_exit
-      |        ^^^^^^^^^^^^^ Cannot resolve import `does_not_exit`
+      |        ^^^^^^^^^^^^^
     3 |
     4 | y = 4 / 0
       |
 
-    warning: lint:division-by-zero
-     --> <temp_dir>/test.py:4:5
+    warning: lint:division-by-zero: Cannot divide object of type `Literal[4]` by zero
+     --> test.py:4:5
       |
     2 | import does_not_exit
     3 |
     4 | y = 4 / 0
-      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^
     5 |
     6 | for a in range(0, int(y)):
       |
@@ -439,22 +549,22 @@ fn cli_rule_severity_precedence() -> anyhow::Result<()> {
     success: false
     exit_code: 1
     ----- stdout -----
-    error: lint:division-by-zero
-     --> <temp_dir>/test.py:2:5
+    error: lint:division-by-zero: Cannot divide object of type `Literal[4]` by zero
+     --> test.py:2:5
       |
     2 | y = 4 / 0
-      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^
     3 |
     4 | for a in range(0, int(y)):
       |
 
-    warning: lint:possibly-unresolved-reference
-     --> <temp_dir>/test.py:7:7
+    warning: lint:possibly-unresolved-reference: Name `x` used when possibly not defined
+     --> test.py:7:7
       |
     5 |     x = a
     6 |
     7 | print(x)  # possibly-unresolved-reference
-      |       ^ Name `x` used when possibly not defined
+      |       ^
       |
 
     Found 2 diagnostics
@@ -476,11 +586,11 @@ fn cli_rule_severity_precedence() -> anyhow::Result<()> {
     success: true
     exit_code: 0
     ----- stdout -----
-    warning: lint:division-by-zero
-     --> <temp_dir>/test.py:2:5
+    warning: lint:division-by-zero: Cannot divide object of type `Literal[4]` by zero
+     --> test.py:2:5
       |
     2 | y = 4 / 0
-      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^
     3 |
     4 | for a in range(0, int(y)):
       |
@@ -513,7 +623,7 @@ fn configuration_unknown_rules() -> anyhow::Result<()> {
     exit_code: 0
     ----- stdout -----
     warning: unknown-rule
-     --> <temp_dir>/pyproject.toml:3:1
+     --> pyproject.toml:3:1
       |
     2 | [tool.knot.rules]
     3 | division-by-zer = "warn" # incorrect rule name
@@ -555,11 +665,11 @@ fn exit_code_only_warnings() -> anyhow::Result<()> {
     success: true
     exit_code: 0
     ----- stdout -----
-    warning: lint:unresolved-reference
-     --> <temp_dir>/test.py:1:7
+    warning: lint:unresolved-reference: Name `x` used when not defined
+     --> test.py:1:7
       |
     1 | print(x)  # [unresolved-reference]
-      |       ^ Name `x` used when not defined
+      |       ^
       |
 
     Found 1 diagnostic
@@ -585,7 +695,7 @@ fn exit_code_only_info() -> anyhow::Result<()> {
     exit_code: 0
     ----- stdout -----
     info: revealed-type: Revealed type
-     --> <temp_dir>/test.py:3:1
+     --> test.py:3:1
       |
     2 | from typing_extensions import reveal_type
     3 | reveal_type(1)
@@ -615,7 +725,7 @@ fn exit_code_only_info_and_error_on_warning_is_true() -> anyhow::Result<()> {
     exit_code: 0
     ----- stdout -----
     info: revealed-type: Revealed type
-     --> <temp_dir>/test.py:3:1
+     --> test.py:3:1
       |
     2 | from typing_extensions import reveal_type
     3 | reveal_type(1)
@@ -638,11 +748,11 @@ fn exit_code_no_errors_but_error_on_warning_is_true() -> anyhow::Result<()> {
     success: false
     exit_code: 1
     ----- stdout -----
-    warning: lint:unresolved-reference
-     --> <temp_dir>/test.py:1:7
+    warning: lint:unresolved-reference: Name `x` used when not defined
+     --> test.py:1:7
       |
     1 | print(x)  # [unresolved-reference]
-      |       ^ Name `x` used when not defined
+      |       ^
       |
 
     Found 1 diagnostic
@@ -670,11 +780,11 @@ fn exit_code_no_errors_but_error_on_warning_is_enabled_in_configuration() -> any
     success: false
     exit_code: 1
     ----- stdout -----
-    warning: lint:unresolved-reference
-     --> <temp_dir>/test.py:1:7
+    warning: lint:unresolved-reference: Name `x` used when not defined
+     --> test.py:1:7
       |
     1 | print(x)  # [unresolved-reference]
-      |       ^ Name `x` used when not defined
+      |       ^
       |
 
     Found 1 diagnostic
@@ -699,20 +809,20 @@ fn exit_code_both_warnings_and_errors() -> anyhow::Result<()> {
     success: false
     exit_code: 1
     ----- stdout -----
-    warning: lint:unresolved-reference
-     --> <temp_dir>/test.py:2:7
+    warning: lint:unresolved-reference: Name `x` used when not defined
+     --> test.py:2:7
       |
     2 | print(x)     # [unresolved-reference]
-      |       ^ Name `x` used when not defined
+      |       ^
     3 | print(4[1])  # [non-subscriptable]
       |
 
-    error: lint:non-subscriptable
-     --> <temp_dir>/test.py:3:7
+    error: lint:non-subscriptable: Cannot subscript object of type `Literal[4]` with no `__getitem__` method
+     --> test.py:3:7
       |
     2 | print(x)     # [unresolved-reference]
     3 | print(4[1])  # [non-subscriptable]
-      |       ^ Cannot subscript object of type `Literal[4]` with no `__getitem__` method
+      |       ^
       |
 
     Found 2 diagnostics
@@ -737,20 +847,20 @@ fn exit_code_both_warnings_and_errors_and_error_on_warning_is_true() -> anyhow::
     success: false
     exit_code: 1
     ----- stdout -----
-    warning: lint:unresolved-reference
-     --> <temp_dir>/test.py:2:7
+    warning: lint:unresolved-reference: Name `x` used when not defined
+     --> test.py:2:7
       |
     2 | print(x)     # [unresolved-reference]
-      |       ^ Name `x` used when not defined
+      |       ^
     3 | print(4[1])  # [non-subscriptable]
       |
 
-    error: lint:non-subscriptable
-     --> <temp_dir>/test.py:3:7
+    error: lint:non-subscriptable: Cannot subscript object of type `Literal[4]` with no `__getitem__` method
+     --> test.py:3:7
       |
     2 | print(x)     # [unresolved-reference]
     3 | print(4[1])  # [non-subscriptable]
-      |       ^ Cannot subscript object of type `Literal[4]` with no `__getitem__` method
+      |       ^
       |
 
     Found 2 diagnostics
@@ -775,20 +885,20 @@ fn exit_code_exit_zero_is_true() -> anyhow::Result<()> {
     success: true
     exit_code: 0
     ----- stdout -----
-    warning: lint:unresolved-reference
-     --> <temp_dir>/test.py:2:7
+    warning: lint:unresolved-reference: Name `x` used when not defined
+     --> test.py:2:7
       |
     2 | print(x)     # [unresolved-reference]
-      |       ^ Name `x` used when not defined
+      |       ^
     3 | print(4[1])  # [non-subscriptable]
       |
 
-    error: lint:non-subscriptable
-     --> <temp_dir>/test.py:3:7
+    error: lint:non-subscriptable: Cannot subscript object of type `Literal[4]` with no `__getitem__` method
+     --> test.py:3:7
       |
     2 | print(x)     # [unresolved-reference]
     3 | print(4[1])  # [non-subscriptable]
-      |       ^ Cannot subscript object of type `Literal[4]` with no `__getitem__` method
+      |       ^
       |
 
     Found 2 diagnostics
@@ -835,22 +945,22 @@ fn user_configuration() -> anyhow::Result<()> {
     success: true
     exit_code: 0
     ----- stdout -----
-    warning: lint:division-by-zero
-     --> <temp_dir>/project/main.py:2:5
+    warning: lint:division-by-zero: Cannot divide object of type `Literal[4]` by zero
+     --> main.py:2:5
       |
     2 | y = 4 / 0
-      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^
     3 |
     4 | for a in range(0, int(y)):
       |
 
-    warning: lint:possibly-unresolved-reference
-     --> <temp_dir>/project/main.py:7:7
+    warning: lint:possibly-unresolved-reference: Name `x` used when possibly not defined
+     --> main.py:7:7
       |
     5 |     x = a
     6 |
     7 | print(x)
-      |       ^ Name `x` used when possibly not defined
+      |       ^
       |
 
     Found 2 diagnostics
@@ -877,22 +987,22 @@ fn user_configuration() -> anyhow::Result<()> {
     success: false
     exit_code: 1
     ----- stdout -----
-    warning: lint:division-by-zero
-     --> <temp_dir>/project/main.py:2:5
+    warning: lint:division-by-zero: Cannot divide object of type `Literal[4]` by zero
+     --> main.py:2:5
       |
     2 | y = 4 / 0
-      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^
     3 |
     4 | for a in range(0, int(y)):
       |
 
-    error: lint:possibly-unresolved-reference
-     --> <temp_dir>/project/main.py:7:7
+    error: lint:possibly-unresolved-reference: Name `x` used when possibly not defined
+     --> main.py:7:7
       |
     5 |     x = a
     6 |
     7 | print(x)
-      |       ^ Name `x` used when possibly not defined
+      |       ^
       |
 
     Found 2 diagnostics
@@ -935,29 +1045,29 @@ fn check_specific_paths() -> anyhow::Result<()> {
     success: false
     exit_code: 1
     ----- stdout -----
-    error: lint:unresolved-import
-     --> <temp_dir>/project/tests/test_main.py:2:8
-      |
-    2 | import does_not_exist  # error: unresolved-import
-      |        ^^^^^^^^^^^^^^ Cannot resolve import `does_not_exist`
-      |
-
-    error: lint:division-by-zero
-     --> <temp_dir>/project/main.py:2:5
+    error: lint:division-by-zero: Cannot divide object of type `Literal[4]` by zero
+     --> project/main.py:2:5
       |
     2 | y = 4 / 0  # error: division-by-zero
-      |     ^^^^^ Cannot divide object of type `Literal[4]` by zero
+      |     ^^^^^
       |
 
-    error: lint:unresolved-import
-     --> <temp_dir>/project/other.py:2:6
+    error: lint:unresolved-import: Cannot resolve import `main2`
+     --> project/other.py:2:6
       |
     2 | from main2 import z  # error: unresolved-import
-      |      ^^^^^ Cannot resolve import `main2`
+      |      ^^^^^
     3 |
     4 | print(z)
       |
 
+    error: lint:unresolved-import: Cannot resolve import `does_not_exist`
+     --> project/tests/test_main.py:2:8
+      |
+    2 | import does_not_exist  # error: unresolved-import
+      |        ^^^^^^^^^^^^^^
+      |
+
     Found 3 diagnostics
 
     ----- stderr -----
@@ -972,22 +1082,22 @@ fn check_specific_paths() -> anyhow::Result<()> {
     success: false
     exit_code: 1
     ----- stdout -----
-    error: lint:unresolved-import
-     --> <temp_dir>/project/tests/test_main.py:2:8
-      |
-    2 | import does_not_exist  # error: unresolved-import
-      |        ^^^^^^^^^^^^^^ Cannot resolve import `does_not_exist`
-      |
-
-    error: lint:unresolved-import
-     --> <temp_dir>/project/other.py:2:6
+    error: lint:unresolved-import: Cannot resolve import `main2`
+     --> project/other.py:2:6
       |
     2 | from main2 import z  # error: unresolved-import
-      |      ^^^^^ Cannot resolve import `main2`
+      |      ^^^^^
     3 |
     4 | print(z)
       |
 
+    error: lint:unresolved-import: Cannot resolve import `does_not_exist`
+     --> project/tests/test_main.py:2:8
+      |
+    2 | import does_not_exist  # error: unresolved-import
+      |        ^^^^^^^^^^^^^^
+      |
+
     Found 2 diagnostics
 
     ----- stderr -----
@@ -1042,8 +1152,8 @@ fn concise_diagnostics() -> anyhow::Result<()> {
     success: false
     exit_code: 1
     ----- stdout -----
-    warning[lint:unresolved-reference] <temp_dir>/test.py:2:7: Name `x` used when not defined
-    error[lint:non-subscriptable] <temp_dir>/test.py:3:7: Cannot subscript object of type `Literal[4]` with no `__getitem__` method
+    warning[lint:unresolved-reference] test.py:2:7: Name `x` used when not defined
+    error[lint:non-subscriptable] test.py:3:7: Cannot subscript object of type `Literal[4]` with no `__getitem__` method
     Found 2 diagnostics
 
     ----- stderr -----
@@ -1076,7 +1186,7 @@ fn concise_revealed_type() -> anyhow::Result<()> {
     success: true
     exit_code: 0
     ----- stdout -----
-    info[revealed-type] <temp_dir>/test.py:5:1: Revealed type: `Literal["hello"]`
+    info[revealed-type] test.py:5:1: Revealed type: `Literal["hello"]`
     Found 1 diagnostic
 
     ----- stderr -----

crates/red_knot_ide/src/goto.rs

@@ -272,9 +272,9 @@ mod tests {
             "#,
         );
 
-        assert_snapshot!(test.goto_type_definition(), @r###"
+        assert_snapshot!(test.goto_type_definition(), @r"
         info: lint:goto-type-definition: Type definition
-         --> /main.py:2:19
+         --> main.py:2:19
           |
         2 |             class Test: ...
           |                   ^^^^
@@ -282,14 +282,14 @@ mod tests {
         4 |             ab = Test()
           |
         info: Source
-         --> /main.py:4:13
+         --> main.py:4:13
           |
         2 |             class Test: ...
         3 |
         4 |             ab = Test()
           |             ^^
           |
-        "###);
+        ");
     }
 
     #[test]
@@ -304,9 +304,9 @@ mod tests {
         "#,
         );
 
-        assert_snapshot!(test.goto_type_definition(), @r###"
+        assert_snapshot!(test.goto_type_definition(), @r"
         info: lint:goto-type-definition: Type definition
-         --> /main.py:2:17
+         --> main.py:2:17
           |
         2 |             def foo(a, b): ...
           |                 ^^^
@@ -314,14 +314,14 @@ mod tests {
         4 |             ab = foo
           |
         info: Source
-         --> /main.py:6:13
+         --> main.py:6:13
           |
         4 |             ab = foo
         5 |
         6 |             ab
           |             ^^
           |
-        "###);
+        ");
     }
 
     #[test]
@@ -344,7 +344,7 @@ mod tests {
 
         assert_snapshot!(test.goto_type_definition(), @r"
         info: lint:goto-type-definition: Type definition
-         --> /main.py:3:17
+         --> main.py:3:17
           |
         3 |             def foo(a, b): ...
           |                 ^^^
@@ -352,7 +352,7 @@ mod tests {
         5 |             def bar(a, b): ...
           |
         info: Source
-          --> /main.py:12:13
+          --> main.py:12:13
            |
         10 |                 a = bar
         11 |
@@ -361,7 +361,7 @@ mod tests {
            |
 
         info: lint:goto-type-definition: Type definition
-         --> /main.py:5:17
+         --> main.py:5:17
           |
         3 |             def foo(a, b): ...
         4 |
@@ -371,7 +371,7 @@ mod tests {
         7 |             if random.choice():
           |
         info: Source
-          --> /main.py:12:13
+          --> main.py:12:13
            |
         10 |                 a = bar
         11 |
@@ -395,13 +395,13 @@ mod tests {
 
         assert_snapshot!(test.goto_type_definition(), @r"
         info: lint:goto-type-definition: Type definition
-         --> /lib.py:1:1
+         --> lib.py:1:1
           |
         1 | a = 10
           | ^^^^^^
           |
         info: Source
-         --> /main.py:4:13
+         --> main.py:4:13
           |
         2 |             import lib
         3 |
@@ -433,7 +433,7 @@ mod tests {
         440 |     def __new__(cls, object: object = ...) -> Self: ...
             |
         info: Source
-         --> /main.py:4:13
+         --> main.py:4:13
           |
         2 |             a: str = "test"
         3 |
@@ -462,7 +462,7 @@ mod tests {
         440 |     def __new__(cls, object: object = ...) -> Self: ...
             |
         info: Source
-         --> /main.py:2:22
+         --> main.py:2:22
           |
         2 |             a: str = "test"
           |                      ^^^^^^
@@ -478,20 +478,20 @@ mod tests {
             "#,
         );
 
-        assert_snapshot!(test.goto_type_definition(), @r###"
+        assert_snapshot!(test.goto_type_definition(), @r"
         info: lint:goto-type-definition: Type definition
-         --> /main.py:2:24
+         --> main.py:2:24
           |
         2 |             type Alias[T: int = bool] = list[T]
           |                        ^
           |
         info: Source
-         --> /main.py:2:46
+         --> main.py:2:46
           |
         2 |             type Alias[T: int = bool] = list[T]
           |                                              ^
           |
-        "###);
+        ");
     }
 
     #[test]
@@ -544,7 +544,7 @@ mod tests {
         440 |     def __new__(cls, object: object = ...) -> Self: ...
             |
         info: Source
-         --> /main.py:4:18
+         --> main.py:4:18
           |
         2 |             def test(a: str): ...
         3 |
@@ -579,7 +579,7 @@ mod tests {
         233 |     def __new__(cls, x: ConvertibleToInt = ..., /) -> Self: ...
             |
         info: Source
-         --> /main.py:4:18
+         --> main.py:4:18
           |
         2 |             def test(a: str): ...
         3 |
@@ -613,7 +613,7 @@ f(**kwargs<CURSOR>)
         1088 |     # Also multiprocessing.managers.SyncManager.dict()
              |
         info: Source
-         --> /main.py:6:5
+         --> main.py:6:5
           |
         4 | kwargs = { "name": "test"}
         5 |
@@ -644,7 +644,7 @@ f(**kwargs<CURSOR>)
         440 |     def __new__(cls, object: object = ...) -> Self: ...
             |
         info: Source
-         --> /main.py:3:17
+         --> main.py:3:17
           |
         2 |             def foo(a: str):
         3 |                 a
@@ -666,23 +666,23 @@ f(**kwargs<CURSOR>)
             "#,
         );
 
-        assert_snapshot!(test.goto_type_definition(), @r###"
+        assert_snapshot!(test.goto_type_definition(), @r"
         info: lint:goto-type-definition: Type definition
-         --> /main.py:2:19
+         --> main.py:2:19
           |
         2 |             class X:
           |                   ^
         3 |                 def foo(a, b): ...
           |
         info: Source
-         --> /main.py:7:13
+         --> main.py:7:13
           |
         5 |             x = X()
         6 |
         7 |             x.foo()
           |             ^
           |
-        "###);
+        ");
     }
 
     #[test]
@@ -695,9 +695,9 @@ f(**kwargs<CURSOR>)
             "#,
         );
 
-        assert_snapshot!(test.goto_type_definition(), @r###"
+        assert_snapshot!(test.goto_type_definition(), @r"
         info: lint:goto-type-definition: Type definition
-         --> /main.py:2:17
+         --> main.py:2:17
           |
         2 |             def foo(a, b): ...
           |                 ^^^
@@ -705,14 +705,14 @@ f(**kwargs<CURSOR>)
         4 |             foo()
           |
         info: Source
-         --> /main.py:4:13
+         --> main.py:4:13
           |
         2 |             def foo(a, b): ...
         3 |
         4 |             foo()
           |             ^^^
           |
-        "###);
+        ");
     }
 
     #[test]
@@ -737,7 +737,7 @@ f(**kwargs<CURSOR>)
         440 |     def __new__(cls, object: object = ...) -> Self: ...
             |
         info: Source
-         --> /main.py:4:27
+         --> main.py:4:27
           |
         2 |             def foo(a: str | None, b):
         3 |                 if a is not None:
@@ -767,7 +767,7 @@ f(**kwargs<CURSOR>)
         672 |         def __bool__(self) -> Literal[False]: ...
             |
         info: Source
-         --> /main.py:3:17
+         --> main.py:3:17
           |
         2 |             def foo(a: str | None, b):
         3 |                 a
@@ -785,7 +785,7 @@ f(**kwargs<CURSOR>)
         440 |     def __new__(cls, object: object = ...) -> Self: ...
             |
         info: Source
-         --> /main.py:3:17
+         --> main.py:3:17
           |
         2 |             def foo(a: str | None, b):
         3 |                 a

crates/red_knot_ide/src/hover.rs

@@ -156,7 +156,7 @@ mod tests {
         ```
         ---------------------------------------------
         info: lint:hover: Hovered content is
-         --> /main.py:4:9
+         --> main.py:4:9
           |
         2 |         a = 10
         3 |
@@ -192,7 +192,7 @@ mod tests {
         ```
         ---------------------------------------------
         info: lint:hover: Hovered content is
-          --> /main.py:10:9
+          --> main.py:10:9
            |
          9 |         foo = Foo()
         10 |         foo.a
@@ -214,7 +214,7 @@ mod tests {
         "#,
         );
 
-        assert_snapshot!(test.hover(), @r###"
+        assert_snapshot!(test.hover(), @r"
         def foo(a, b) -> Unknown
         ---------------------------------------------
         ```text
@@ -222,7 +222,7 @@ mod tests {
         ```
         ---------------------------------------------
         info: lint:hover: Hovered content is
-         --> /main.py:4:13
+         --> main.py:4:13
           |
         2 |             def foo(a, b): ...
         3 |
@@ -231,7 +231,7 @@ mod tests {
           |             |
           |             source
           |
-        "###);
+        ");
     }
 
     #[test]
@@ -251,7 +251,7 @@ mod tests {
         ```
         ---------------------------------------------
         info: lint:hover: Hovered content is
-         --> /main.py:3:17
+         --> main.py:3:17
           |
         2 |             def foo(a: int, b: int, c: int):
         3 |                 a + b == c
@@ -282,7 +282,7 @@ mod tests {
         ```
         ---------------------------------------------
         info: lint:hover: Hovered content is
-         --> /main.py:4:18
+         --> main.py:4:18
           |
         2 |             def test(a: int): ...
         3 |
@@ -312,7 +312,7 @@ mod tests {
             "#,
         );
 
-        assert_snapshot!(test.hover(), @r###"
+        assert_snapshot!(test.hover(), @r"
         (def foo(a, b) -> Unknown) | (def bar(a, b) -> Unknown)
         ---------------------------------------------
         ```text
@@ -320,7 +320,7 @@ mod tests {
         ```
         ---------------------------------------------
         info: lint:hover: Hovered content is
-          --> /main.py:12:13
+          --> main.py:12:13
            |
         10 |                 a = bar
         11 |
@@ -329,7 +329,7 @@ mod tests {
            |             |
            |             source
            |
-        "###);
+        ");
     }
 
     #[test]
@@ -352,7 +352,7 @@ mod tests {
         ```
         ---------------------------------------------
         info: lint:hover: Hovered content is
-         --> /main.py:4:13
+         --> main.py:4:13
           |
         2 |             import lib
         3 |
@@ -381,7 +381,7 @@ mod tests {
         ```
         ---------------------------------------------
         info: lint:hover: Hovered content is
-         --> /main.py:2:46
+         --> main.py:2:46
           |
         2 |             type Alias[T: int = bool] = list[T]
           |                                              ^- Cursor offset
@@ -407,7 +407,7 @@ mod tests {
         ```
         ---------------------------------------------
         info: lint:hover: Hovered content is
-         --> /main.py:2:53
+         --> main.py:2:53
           |
         2 |             type Alias[**P = [int, str]] = Callable[P, int]
           |                                                     ^- Cursor offset
@@ -433,7 +433,7 @@ mod tests {
         ```
         ---------------------------------------------
         info: lint:hover: Hovered content is
-         --> /main.py:2:43
+         --> main.py:2:43
           |
         2 |             type Alias[*Ts = ()] = tuple[*Ts]
           |                                           ^^- Cursor offset
@@ -461,7 +461,7 @@ mod tests {
         ```
         ---------------------------------------------
         info: lint:hover: Hovered content is
-         --> /main.py:3:13
+         --> main.py:3:13
           |
         2 |         class Foo:
         3 |             a: int
@@ -490,7 +490,7 @@ mod tests {
         ```
         ---------------------------------------------
         info: lint:hover: Hovered content is
-         --> /main.py:4:27
+         --> main.py:4:27
           |
         2 |             def foo(a: str | None, b):
         3 |                 if a is not None:

crates/red_knot_project/resources/test/corpus/self_referential_function_annotation.py

@@ -0,0 +1,4 @@
+from __future__ import annotations
+
+def foo(a: foo()):
+    pass

crates/red_knot_project/src/lib.rs

@@ -11,7 +11,7 @@ use red_knot_python_semantic::register_lints;
 use red_knot_python_semantic::types::check_types;
 use ruff_db::diagnostic::{
     create_parse_diagnostic, create_unsupported_syntax_diagnostic, Annotation, Diagnostic,
-    DiagnosticId, Severity, Span,
+    DiagnosticId, Severity, Span, SubDiagnostic,
 };
 use ruff_db::files::File;
 use ruff_db::parsed::parsed_module;
@@ -20,8 +20,11 @@ use ruff_db::system::{SystemPath, SystemPathBuf};
 use rustc_hash::FxHashSet;
 use salsa::Durability;
 use salsa::Setter;
+use std::backtrace::BacktraceStatus;
+use std::panic::{AssertUnwindSafe, UnwindSafe};
 use std::sync::Arc;
 use thiserror::Error;
+use tracing::error;
 
 pub mod combine;
 
@@ -187,30 +190,66 @@ impl Project {
                 .map(IOErrorDiagnostic::to_diagnostic),
         );
 
-        let result = Arc::new(std::sync::Mutex::new(diagnostics));
-        let inner_result = Arc::clone(&result);
+        let file_diagnostics = Arc::new(std::sync::Mutex::new(vec![]));
 
-        let db = db.clone();
-        let project_span = project_span.clone();
+        {
+            let file_diagnostics = Arc::clone(&file_diagnostics);
+            let db = db.clone();
+            let project_span = project_span.clone();
 
-        rayon::scope(move |scope| {
-            for file in &files {
-                let result = inner_result.clone();
-                let db = db.clone();
-                let project_span = project_span.clone();
+            rayon::scope(move |scope| {
+                for file in &files {
+                    let result = Arc::clone(&file_diagnostics);
+                    let db = db.clone();
+                    let project_span = project_span.clone();
 
-                scope.spawn(move |_| {
-                    let check_file_span =
-                        tracing::debug_span!(parent: &project_span, "check_file", ?file);
-                    let _entered = check_file_span.entered();
+                    scope.spawn(move |_| {
+                        let check_file_span =
+                            tracing::debug_span!(parent: &project_span, "check_file", ?file);
+                        let _entered = check_file_span.entered();
 
-                    let file_diagnostics = check_file_impl(&db, file);
-                    result.lock().unwrap().extend(file_diagnostics);
-                });
+                        let file_diagnostics = check_file_impl(&db, file);
+                        result.lock().unwrap().extend(file_diagnostics);
+                    });
+                }
+            });
+        }
+
+        let mut file_diagnostics = Arc::into_inner(file_diagnostics)
+            .unwrap()
+            .into_inner()
+            .unwrap();
+        // We sort diagnostics in a way that keeps them in source order
+        // and grouped by file. After that, we fall back to severity
+        // (with fatal messages sorting before info messages) and then
+        // finally the diagnostic ID.
+        file_diagnostics.sort_by(|d1, d2| {
+            if let (Some(span1), Some(span2)) = (d1.primary_span(), d2.primary_span()) {
+                let order = span1
+                    .file()
+                    .path(db)
+                    .as_str()
+                    .cmp(span2.file().path(db).as_str());
+                if order.is_ne() {
+                    return order;
+                }
+
+                if let (Some(range1), Some(range2)) = (span1.range(), span2.range()) {
+                    let order = range1.start().cmp(&range2.start());
+                    if order.is_ne() {
+                        return order;
+                    }
+                }
             }
+            // Reverse so that, e.g., Fatal sorts before Info.
+            let order = d1.severity().cmp(&d2.severity()).reverse();
+            if order.is_ne() {
+                return order;
+            }
+            d1.id().cmp(&d2.id())
         });
-
-        Arc::into_inner(result).unwrap().into_inner().unwrap()
+        diagnostics.extend(file_diagnostics);
+        diagnostics
     }
 
     pub(crate) fn check_file(self, db: &dyn Db, file: File) -> Vec<Diagnostic> {
@@ -314,20 +353,23 @@ impl Project {
     /// * It has a [`SystemPath`] and belongs to a package's `src` files
     /// * It has a [`SystemVirtualPath`](ruff_db::system::SystemVirtualPath)
     pub fn is_file_open(self, db: &dyn Db, file: File) -> bool {
+        let path = file.path(db);
+
+        // Try to return early to avoid adding a dependency on `open_files` or `file_set` which
+        // both have a durability of `LOW`.
+        if path.is_vendored_path() {
+            return false;
+        }
+
         if let Some(open_files) = self.open_files(db) {
             open_files.contains(&file)
         } else if file.path(db).is_system_path() {
-            self.contains_file(db, file)
+            self.files(db).contains(&file)
         } else {
             file.path(db).is_system_virtual_path()
         }
     }
 
-    /// Returns `true` if `file` is a first-party file part of this package.
-    pub fn contains_file(self, db: &dyn Db, file: File) -> bool {
-        self.files(db).contains(&file)
-    }
-
     #[tracing::instrument(level = "debug", skip(self, db))]
     pub fn remove_file(self, db: &mut dyn Db, file: File) {
         tracing::debug!(
@@ -432,7 +474,16 @@ fn check_file_impl(db: &dyn Db, file: File) -> Vec<Diagnostic> {
             .map(|error| create_unsupported_syntax_diagnostic(file, error)),
     );
 
-    diagnostics.extend(check_types(db.upcast(), file).into_iter().cloned());
+    {
+        let db = AssertUnwindSafe(db);
+        match catch(&**db, file, || check_types(db.upcast(), file)) {
+            Ok(Some(type_check_diagnostics)) => {
+                diagnostics.extend(type_check_diagnostics.into_iter().cloned());
+            }
+            Ok(None) => {}
+            Err(diagnostic) => diagnostics.push(diagnostic),
+        }
+    }
 
     diagnostics.sort_unstable_by_key(|diagnostic| {
         diagnostic
@@ -523,6 +574,87 @@ enum IOErrorKind {
     SourceText(#[from] SourceTextError),
 }
 
+fn catch<F, R>(db: &dyn Db, file: File, f: F) -> Result<Option<R>, Diagnostic>
+where
+    F: FnOnce() -> R + UnwindSafe,
+{
+    match ruff_db::panic::catch_unwind(|| {
+        // Ignore salsa errors
+        salsa::Cancelled::catch(f).ok()
+    }) {
+        Ok(result) => Ok(result),
+        Err(error) => {
+            use std::fmt::Write;
+            let mut message = String::new();
+            message.push_str("Panicked");
+
+            if let Some(location) = error.location {
+                let _ = write!(&mut message, " at {location}");
+            }
+
+            let _ = write!(
+                &mut message,
+                " when checking `{file}`",
+                file = file.path(db)
+            );
+
+            if let Some(payload) = error.payload.as_str() {
+                let _ = write!(&mut message, ": `{payload}`");
+            }
+
+            let mut diagnostic = Diagnostic::new(DiagnosticId::Panic, Severity::Fatal, message);
+            diagnostic.sub(SubDiagnostic::new(
+                Severity::Info,
+                "This indicates a bug in Red Knot.",
+            ));
+
+            let report_message = "If you could open an issue at https://github.com/astral-sh/ruff/issues/new?title=%5Bred-knot%5D:%20panic we'd be very appreciative!";
+            diagnostic.sub(SubDiagnostic::new(Severity::Info, report_message));
+            diagnostic.sub(SubDiagnostic::new(
+                Severity::Info,
+                format!(
+                    "Platform: {os} {arch}",
+                    os = std::env::consts::OS,
+                    arch = std::env::consts::ARCH
+                ),
+            ));
+            diagnostic.sub(SubDiagnostic::new(
+                Severity::Info,
+                format!(
+                    "Args: {args:?}",
+                    args = std::env::args().collect::<Vec<_>>()
+                ),
+            ));
+
+            if let Some(backtrace) = error.backtrace {
+                match backtrace.status() {
+                    BacktraceStatus::Disabled => {
+                        diagnostic.sub(SubDiagnostic::new(
+                            Severity::Info,
+                            "run with `RUST_BACKTRACE=1` environment variable to show the full backtrace information",
+                        ));
+                    }
+                    BacktraceStatus::Captured => {
+                        diagnostic.sub(SubDiagnostic::new(
+                            Severity::Info,
+                            format!("Backtrace:\n{backtrace}"),
+                        ));
+                    }
+                    _ => {}
+                }
+            }
+
+            if let Some(backtrace) = error.salsa_backtrace {
+                salsa::attach(db, || {
+                    diagnostic.sub(SubDiagnostic::new(Severity::Info, backtrace.to_string()));
+                });
+            }
+
+            Err(diagnostic)
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::db::tests::TestDb;

crates/red_knot_project/src/metadata/options.rs

@@ -32,6 +32,9 @@ pub struct Options {
 
     #[serde(skip_serializing_if = "Option::is_none")]
     pub terminal: Option<TerminalOptions>,
+
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub respect_ignore_files: Option<bool>,
 }
 
 impl Options {
@@ -65,9 +68,7 @@ impl Options {
             .and_then(|env| env.python_platform.as_deref().cloned())
             .unwrap_or_else(|| {
                 let default = PythonPlatform::default();
-                tracing::info!(
-                    "Defaulting to default python version for this platform: '{default}'",
-                );
+                tracing::info!("Defaulting to python-platform `{default}`");
                 default
             });
         ProgramSettings {
@@ -133,7 +134,7 @@ impl Options {
     pub(crate) fn to_settings(&self, db: &dyn Db) -> (Settings, Vec<OptionDiagnostic>) {
         let (rules, diagnostics) = self.to_rule_selection(db);
 
-        let mut settings = Settings::new(rules);
+        let mut settings = Settings::new(rules, self.respect_ignore_files);
 
         if let Some(terminal) = self.terminal.as_ref() {
             settings.set_terminal(TerminalSettings {

crates/red_knot_project/src/metadata/settings.rs

@@ -21,13 +21,16 @@ pub struct Settings {
     rules: Arc<RuleSelection>,
 
     terminal: TerminalSettings,
+
+    respect_ignore_files: bool,
 }
 
 impl Settings {
-    pub fn new(rules: RuleSelection) -> Self {
+    pub fn new(rules: RuleSelection, respect_ignore_files: Option<bool>) -> Self {
         Self {
             rules: Arc::new(rules),
             terminal: TerminalSettings::default(),
+            respect_ignore_files: respect_ignore_files.unwrap_or(true),
         }
     }
 
@@ -35,6 +38,10 @@ impl Settings {
         &self.rules
     }
 
+    pub fn respect_ignore_files(&self) -> bool {
+        self.respect_ignore_files
+    }
+
     pub fn to_rules(&self) -> Arc<RuleSelection> {
         self.rules.clone()
     }

crates/red_knot_project/src/walk.rs

@@ -129,7 +129,11 @@ impl<'a> ProjectFilesWalker<'a> {
     {
         let mut paths = paths.into_iter();
 
-        let mut walker = db.system().walk_directory(paths.next()?.as_ref());
+        let mut walker = db
+            .system()
+            .walk_directory(paths.next()?.as_ref())
+            .standard_filters(db.project().settings(db).respect_ignore_files())
+            .ignore_hidden(false);
 
         for path in paths {
             walker = walker.add(path);

crates/red_knot_python_semantic/mdtest.py

@@ -20,6 +20,12 @@ from watchfiles import Change, watch
 
 CRATE_NAME: Final = "red_knot_python_semantic"
 CRATE_ROOT: Final = Path(__file__).resolve().parent
+RED_KNOT_VENDORED: Final = CRATE_ROOT.parent / "red_knot_vendored"
+DIRS_TO_WATCH: Final = (
+    CRATE_ROOT,
+    RED_KNOT_VENDORED,
+    CRATE_ROOT.parent / "red_knot_test/src",
+)
 MDTEST_DIR: Final = CRATE_ROOT / "resources" / "mdtest"
 
 
@@ -158,20 +164,24 @@ class MDTestRunner:
         self._run_mdtest()
         self.console.print("[dim]Ready to watch for changes...[/dim]")
 
-        for changes in watch(CRATE_ROOT):
+        for changes in watch(*DIRS_TO_WATCH):
             new_md_files = set()
             changed_md_files = set()
             rust_code_has_changed = False
+            vendored_typeshed_has_changed = False
 
             for change, path_str in changes:
                 path = Path(path_str)
 
-                if path.suffix == ".rs":
-                    rust_code_has_changed = True
-                    continue
-
-                if path.suffix != ".md":
-                    continue
+                match path.suffix:
+                    case ".rs":
+                        rust_code_has_changed = True
+                    case ".pyi" if path.is_relative_to(RED_KNOT_VENDORED):
+                        vendored_typeshed_has_changed = True
+                    case ".md":
+                        pass
+                    case _:
+                        continue
 
                 try:
                     relative_path = Path(path).relative_to(MDTEST_DIR)
@@ -199,6 +209,11 @@ class MDTestRunner:
             if rust_code_has_changed:
                 if self._recompile_tests("Rust code has changed, recompiling tests..."):
                     self._run_mdtest()
+            elif vendored_typeshed_has_changed:
+                if self._recompile_tests(
+                    "Vendored typeshed has changed, recompiling tests..."
+                ):
+                    self._run_mdtest()
             elif new_md_files:
                 files = " ".join(file.as_posix() for file in new_md_files)
                 self._recompile_tests(

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

@@ -46,28 +46,76 @@ def f():
 y: Any = "not an Any"  # error: [invalid-assignment]
 ```
 
-## Subclass
+## Subclasses of `Any`
 
 The spec allows you to define subclasses of `Any`.
 
-TODO: Handle assignments correctly. `Subclass` has an unknown superclass, which might be `int`. The
-assignment to `x` should not be allowed, even when the unknown superclass is `int`. The assignment
-to `y` should be allowed, since `Subclass` might have `int` as a superclass, and is therefore
-assignable to `int`.
+`SubclassOfAny` has an unknown superclass, which might be `int`. The assignment to `x` should not be
+allowed, even when the unknown superclass is `int`. The assignment to `y` should be allowed, since
+`Subclass` might have `int` as a superclass, and is therefore assignable to `int`.
 
 ```py
 from typing import Any
 
-class Subclass(Any): ...
+class SubclassOfAny(Any): ...
 
-reveal_type(Subclass.__mro__)  # revealed: tuple[Literal[Subclass], Any, Literal[object]]
+reveal_type(SubclassOfAny.__mro__)  # revealed: tuple[Literal[SubclassOfAny], Any, Literal[object]]
 
-x: Subclass = 1  # error: [invalid-assignment]
-# TODO: no diagnostic
-y: int = Subclass()  # error: [invalid-assignment]
+x: SubclassOfAny = 1  # error: [invalid-assignment]
+y: int = SubclassOfAny()
+```
 
-def _(s: Subclass):
-    reveal_type(s)  # revealed: Subclass
+`SubclassOfAny` should not be assignable to a final class though, because `SubclassOfAny` could not
+possibly be a subclass of `FinalClass`:
+
+```py
+from typing import final
+
+@final
+class FinalClass: ...
+
+f: FinalClass = SubclassOfAny()  # error: [invalid-assignment]
+
+@final
+class OtherFinalClass: ...
+
+f: FinalClass | OtherFinalClass = SubclassOfAny()  # error: [invalid-assignment]
+```
+
+A subclass of `Any` can also be assigned to arbitrary `Callable` types:
+
+```py
+from typing import Callable, Any
+
+def takes_callable1(f: Callable):
+    f()
+
+takes_callable1(SubclassOfAny())
+
+def takes_callable2(f: Callable[[int], None]):
+    f(1)
+
+takes_callable2(SubclassOfAny())
+```
+
+A subclass of `Any` cannot be assigned to literal types, since those can not be subclassed:
+
+```py
+from typing import Any, Literal
+
+class MockAny(Any):
+    pass
+
+x: Literal[1] = MockAny()  # error: [invalid-assignment]
+```
+
+A use case where subclasses of `Any` come up is in mocking libraries, where the mock object should
+be assignable to (almost) any type:
+
+```py
+from unittest.mock import MagicMock
+
+x: int = MagicMock()
 ```
 
 ## Invalid

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

@@ -225,14 +225,16 @@ Using `Concatenate` as the first argument to `Callable`:
 from typing_extensions import Callable, Concatenate
 
 def _(c: Callable[Concatenate[int, str, ...], int]):
-    reveal_type(c)  # revealed: (*args: @Todo(todo signature *args), **kwargs: @Todo(todo signature **kwargs)) -> int
+    # TODO: Should reveal the correct signature
+    reveal_type(c)  # revealed: (...) -> int
 ```
 
 And, as one of the parameter types:
 
 ```py
 def _(c: Callable[[Concatenate[int, str, ...], int], int]):
-    reveal_type(c)  # revealed: (*args: @Todo(todo signature *args), **kwargs: @Todo(todo signature **kwargs)) -> int
+    # TODO: Should reveal the correct signature
+    reveal_type(c)  # revealed: (...) -> int
 ```
 
 ## Using `typing.ParamSpec`
@@ -276,7 +278,8 @@ from typing_extensions import Callable, TypeVarTuple
 Ts = TypeVarTuple("Ts")
 
 def _(c: Callable[[int, *Ts], int]):
-    reveal_type(c)  # revealed: (*args: @Todo(todo signature *args), **kwargs: @Todo(todo signature **kwargs)) -> int
+    # TODO: Should reveal the correct signature
+    reveal_type(c)  # revealed: (...) -> int
 ```
 
 And, using the legacy syntax using `Unpack`:
@@ -285,7 +288,8 @@ And, using the legacy syntax using `Unpack`:
 from typing_extensions import Unpack
 
 def _(c: Callable[[int, Unpack[Ts]], int]):
-    reveal_type(c)  # revealed: (*args: @Todo(todo signature *args), **kwargs: @Todo(todo signature **kwargs)) -> int
+    # TODO: Should reveal the correct signature
+    reveal_type(c)  # revealed: (...) -> int
 ```
 
 ## Member lookup

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

@@ -56,40 +56,41 @@ def _(
 def bar() -> None:
     return None
 
-def _(
-    a: 1,  # error: [invalid-type-form] "Int literals are not allowed in this context in a type expression"
-    b: 2.3,  # error: [invalid-type-form] "Float literals are not allowed in type expressions"
-    c: 4j,  # error: [invalid-type-form] "Complex literals are not allowed in type expressions"
-    d: True,  # error: [invalid-type-form] "Boolean literals are not allowed in this context in a type expression"
-    e: int | b"foo",  # error: [invalid-type-form] "Bytes literals are not allowed in this context in a type expression"
-    f: 1 and 2,  # error: [invalid-type-form] "Boolean operations are not allowed in type expressions"
-    g: 1 or 2,  # error: [invalid-type-form] "Boolean operations are not allowed in type expressions"
-    h: (foo := 1),  # error: [invalid-type-form] "Named expressions are not allowed in type expressions"
-    i: not 1,  # error: [invalid-type-form] "Unary operations are not allowed in type expressions"
-    j: lambda: 1,  # error: [invalid-type-form] "`lambda` expressions are not allowed in type expressions"
-    k: 1 if True else 2,  # error: [invalid-type-form] "`if` expressions are not allowed in type expressions"
-    l: await 1,  # error: [invalid-type-form] "`await` expressions are not allowed in type expressions"
-    m: (yield 1),  # error: [invalid-type-form] "`yield` expressions are not allowed in type expressions"
-    n: (yield from [1]),  # error: [invalid-type-form] "`yield from` expressions are not allowed in type expressions"
-    o: 1 < 2,  # error: [invalid-type-form] "Comparison expressions are not allowed in type expressions"
-    p: bar(),  # error: [invalid-type-form] "Function calls are not allowed in type expressions"
-    q: int | f"foo",  # error: [invalid-type-form] "F-strings are not allowed in type expressions"
-    r: [1, 2, 3][1:2],  # error: [invalid-type-form] "Slices are not allowed in type expressions"
-):
-    reveal_type(a)  # revealed: Unknown
-    reveal_type(b)  # revealed: Unknown
-    reveal_type(c)  # revealed: Unknown
-    reveal_type(d)  # revealed: Unknown
-    reveal_type(e)  # revealed: int | Unknown
-    reveal_type(f)  # revealed: Unknown
-    reveal_type(g)  # revealed: Unknown
-    reveal_type(h)  # revealed: Unknown
-    reveal_type(i)  # revealed: Unknown
-    reveal_type(j)  # revealed: Unknown
-    reveal_type(k)  # revealed: Unknown
-    reveal_type(p)  # revealed: Unknown
-    reveal_type(q)  # revealed: int | Unknown
-    reveal_type(r)  # revealed: @Todo(unknown type subscript)
+async def outer():  # avoid unrelated syntax errors on yield, yield from, and await
+    def _(
+        a: 1,  # error: [invalid-type-form] "Int literals are not allowed in this context in a type expression"
+        b: 2.3,  # error: [invalid-type-form] "Float literals are not allowed in type expressions"
+        c: 4j,  # error: [invalid-type-form] "Complex literals are not allowed in type expressions"
+        d: True,  # error: [invalid-type-form] "Boolean literals are not allowed in this context in a type expression"
+        e: int | b"foo",  # error: [invalid-type-form] "Bytes literals are not allowed in this context in a type expression"
+        f: 1 and 2,  # error: [invalid-type-form] "Boolean operations are not allowed in type expressions"
+        g: 1 or 2,  # error: [invalid-type-form] "Boolean operations are not allowed in type expressions"
+        h: (foo := 1),  # error: [invalid-type-form] "Named expressions are not allowed in type expressions"
+        i: not 1,  # error: [invalid-type-form] "Unary operations are not allowed in type expressions"
+        j: lambda: 1,  # error: [invalid-type-form] "`lambda` expressions are not allowed in type expressions"
+        k: 1 if True else 2,  # error: [invalid-type-form] "`if` expressions are not allowed in type expressions"
+        l: await 1,  # error: [invalid-type-form] "`await` expressions are not allowed in type expressions"
+        m: (yield 1),  # error: [invalid-type-form] "`yield` expressions are not allowed in type expressions"
+        n: (yield from [1]),  # error: [invalid-type-form] "`yield from` expressions are not allowed in type expressions"
+        o: 1 < 2,  # error: [invalid-type-form] "Comparison expressions are not allowed in type expressions"
+        p: bar(),  # error: [invalid-type-form] "Function calls are not allowed in type expressions"
+        q: int | f"foo",  # error: [invalid-type-form] "F-strings are not allowed in type expressions"
+        r: [1, 2, 3][1:2],  # error: [invalid-type-form] "Slices are not allowed in type expressions"
+    ):
+        reveal_type(a)  # revealed: Unknown
+        reveal_type(b)  # revealed: Unknown
+        reveal_type(c)  # revealed: Unknown
+        reveal_type(d)  # revealed: Unknown
+        reveal_type(e)  # revealed: int | Unknown
+        reveal_type(f)  # revealed: Unknown
+        reveal_type(g)  # revealed: Unknown
+        reveal_type(h)  # revealed: Unknown
+        reveal_type(i)  # revealed: Unknown
+        reveal_type(j)  # revealed: Unknown
+        reveal_type(k)  # revealed: Unknown
+        reveal_type(p)  # revealed: Unknown
+        reveal_type(q)  # revealed: int | Unknown
+        reveal_type(r)  # revealed: @Todo(unknown type subscript)
 ```
 
 ## Invalid Collection based AST nodes

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

@@ -38,8 +38,12 @@ bad_nesting: Literal[LiteralString]  # error: [invalid-type-form]
 ```py
 from typing_extensions import LiteralString
 
-a: LiteralString[str]  # error: [invalid-type-form]
-b: LiteralString["foo"]  # error: [invalid-type-form]
+# error: [invalid-type-form]
+a: LiteralString[str]
+
+# error: [invalid-type-form]
+# error: [unresolved-reference] "Name `foo` used when not defined"
+b: LiteralString["foo"]
 ```
 
 ### As a base class

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

@@ -106,13 +106,13 @@ reveal_type(ChainMapSubclass.__mro__)
 class CounterSubclass(typing.Counter): ...
 
 # TODO: Should be (CounterSubclass, Counter, dict, MutableMapping, Mapping, Collection, Sized, Iterable, Container, Generic, object)
-# revealed: tuple[Literal[CounterSubclass], Literal[Counter], Unknown, Literal[object]]
+# revealed: tuple[Literal[CounterSubclass], Literal[Counter], @Todo(GenericAlias instance), @Todo(`Generic[]` subscript), Literal[object]]
 reveal_type(CounterSubclass.__mro__)
 
 class DefaultDictSubclass(typing.DefaultDict): ...
 
 # TODO: Should be (DefaultDictSubclass, defaultdict, dict, MutableMapping, Mapping, Collection, Sized, Iterable, Container, Generic, object)
-# revealed: tuple[Literal[DefaultDictSubclass], Literal[defaultdict], Unknown, Literal[object]]
+# revealed: tuple[Literal[DefaultDictSubclass], Literal[defaultdict], @Todo(GenericAlias instance), Literal[object]]
 reveal_type(DefaultDictSubclass.__mro__)
 
 class DequeSubclass(typing.Deque): ...
@@ -124,6 +124,6 @@ reveal_type(DequeSubclass.__mro__)
 class OrderedDictSubclass(typing.OrderedDict): ...
 
 # TODO: Should be (OrderedDictSubclass, OrderedDict, dict, MutableMapping, Mapping, Collection, Sized, Iterable, Container, Generic, object)
-# revealed: tuple[Literal[OrderedDictSubclass], Literal[OrderedDict], Unknown, Literal[object]]
+# revealed: tuple[Literal[OrderedDictSubclass], Literal[OrderedDict], @Todo(GenericAlias instance), Literal[object]]
 reveal_type(OrderedDictSubclass.__mro__)
 ```

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

@@ -89,9 +89,12 @@ python-version = "3.12"
 Some of these are not subscriptable:
 
 ```py
-from typing_extensions import Self, TypeAlias
+from typing_extensions import Self, TypeAlias, TypeVar
 
-X: TypeAlias[T] = int  # error: [invalid-type-form]
+T = TypeVar("T")
+
+# error: [invalid-type-form] "Special form `typing.TypeAlias` expected no type parameter"
+X: TypeAlias[T] = int
 
 class Foo[T]:
     # error: [invalid-type-form] "Special form `typing.Self` expected no type parameter"

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

@@ -11,8 +11,6 @@ from typing_extensions import Final, Required, NotRequired, ReadOnly, TypedDict
 X: Final = 42
 Y: Final[int] = 42
 
-# TODO: `TypedDict` is actually valid as a base
-# error: [invalid-base]
 class Bar(TypedDict):
     x: Required[int]
     y: NotRequired[str]

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

@@ -292,3 +292,66 @@ reveal_type(a)  # revealed: Unknown
 # Modifications allowed in this case:
 a = None
 ```
+
+## In stub files
+
+In stub files, we have a minor modification to the rules above: we do not union with `Unknown` for
+undeclared symbols.
+
+### Undeclared and bound
+
+`mod.pyi`:
+
+```pyi
+MyInt = int
+
+class C:
+    MyStr = str
+```
+
+```py
+from mod import MyInt, C
+
+reveal_type(MyInt)  # revealed: Literal[int]
+reveal_type(C.MyStr)  # revealed: Literal[str]
+```
+
+### Undeclared and possibly unbound
+
+`mod.pyi`:
+
+```pyi
+def flag() -> bool:
+    return True
+
+if flag():
+    MyInt = int
+
+    class C:
+        MyStr = str
+```
+
+```py
+# error: [possibly-unbound-import]
+# error: [possibly-unbound-import]
+from mod import MyInt, C
+
+reveal_type(MyInt)  # revealed: Literal[int]
+reveal_type(C.MyStr)  # revealed: Literal[str]
+```
+
+### Undeclared and unbound
+
+`mod.pyi`:
+
+```pyi
+if False:
+    MyInt = int
+```
+
+```py
+# error: [unresolved-import]
+from mod import MyInt
+
+reveal_type(MyInt)  # revealed: Unknown
+```

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

@@ -1,25 +1,25 @@
 # Constructor
 
-When classes are instantiated, Python calls the meta-class `__call__` method, which can either be
-customized by the user or `type.__call__` is used.
+When classes are instantiated, Python calls the metaclass's `__call__` method. The metaclass of most
+Python classes is the class `builtins.type`.
 
-The latter calls the `__new__` method of the class, which is responsible for creating the instance
-and then calls the `__init__` method on the resulting instance to initialize it with the same
-arguments.
+`type.__call__` calls the `__new__` method of the class, which is responsible for creating the
+instance. `__init__` is then called on the constructed instance with the same arguments that were
+passed to `__new__`.
 
-Both `__new__` and `__init__` are looked up using full descriptor protocol, but `__new__` is then
-called as an implicit static, rather than bound method with `cls` passed as the first argument.
-`__init__` has no special handling, it is fetched as bound method and is called just like any other
-dunder method.
+Both `__new__` and `__init__` are looked up using the descriptor protocol, i.e., `__get__` is called
+if these attributes are descriptors. `__new__` is always treated as a static method, i.e., `cls` is
+passed as the first argument. `__init__` has no special handling; it is fetched as a bound method
+and called just like any other dunder method.
 
 `type.__call__` does other things too, but this is not yet handled by us.
 
 Since every class has `object` in it's MRO, the default implementations are `object.__new__` and
 `object.__init__`. They have some special behavior, namely:
 
-- If neither `__new__` nor `__init__` are defined anywhere in the MRO of class (except for `object`)
-    \- no arguments are accepted and `TypeError` is raised if any are passed.
-- If `__new__` is defined, but `__init__` is not - `object.__init__` will allow arbitrary arguments!
+- If neither `__new__` nor `__init__` are defined anywhere in the MRO of class (except for
+    `object`), no arguments are accepted and `TypeError` is raised if any are passed.
+- If `__new__` is defined but `__init__` is not, `object.__init__` will allow arbitrary arguments!
 
 As of today there are a number of behaviors that we do not support:
 
@@ -146,6 +146,25 @@ reveal_type(Foo())  # revealed: Foo
 
 ### Possibly Unbound
 
+#### Possibly unbound `__new__` method
+
+```py
+def _(flag: bool) -> None:
+    class Foo:
+        if flag:
+            def __new__(cls):
+                return object.__new__(cls)
+
+    # error: [call-possibly-unbound-method]
+    reveal_type(Foo())  # revealed: Foo
+
+    # error: [call-possibly-unbound-method]
+    # error: [too-many-positional-arguments]
+    reveal_type(Foo(1))  # revealed: Foo
+```
+
+#### Possibly unbound `__call__` on `__new__` callable
+
 ```py
 def _(flag: bool) -> None:
     class Callable:
@@ -323,3 +342,86 @@ reveal_type(Foo(1))  # revealed: Foo
 # error: [too-many-positional-arguments] "Too many positional arguments to bound method `__init__`: expected 1, got 2"
 reveal_type(Foo(1, 2))  # revealed: Foo
 ```
+
+### Incompatible signatures
+
+```py
+import abc
+
+class Foo:
+    def __new__(cls) -> "Foo":
+        return object.__new__(cls)
+
+    def __init__(self, x):
+        self.x = 42
+
+# error: [missing-argument] "No argument provided for required parameter `x` of bound method `__init__`"
+reveal_type(Foo())  # revealed: Foo
+
+# error: [too-many-positional-arguments] "Too many positional arguments to function `__new__`: expected 0, got 1"
+reveal_type(Foo(42))  # revealed: Foo
+
+class Foo2:
+    def __new__(cls, x) -> "Foo2":
+        return object.__new__(cls)
+
+    def __init__(self):
+        pass
+
+# error: [missing-argument] "No argument provided for required parameter `x` of function `__new__`"
+reveal_type(Foo2())  # revealed: Foo2
+
+# error: [too-many-positional-arguments] "Too many positional arguments to bound method `__init__`: expected 0, got 1"
+reveal_type(Foo2(42))  # revealed: Foo2
+
+class Foo3(metaclass=abc.ABCMeta):
+    def __new__(cls) -> "Foo3":
+        return object.__new__(cls)
+
+    def __init__(self, x):
+        self.x = 42
+
+# error: [missing-argument] "No argument provided for required parameter `x` of bound method `__init__`"
+reveal_type(Foo3())  # revealed: Foo3
+
+# error: [too-many-positional-arguments] "Too many positional arguments to function `__new__`: expected 0, got 1"
+reveal_type(Foo3(42))  # revealed: Foo3
+
+class Foo4(metaclass=abc.ABCMeta):
+    def __new__(cls, x) -> "Foo4":
+        return object.__new__(cls)
+
+    def __init__(self):
+        pass
+
+# error: [missing-argument] "No argument provided for required parameter `x` of function `__new__`"
+reveal_type(Foo4())  # revealed: Foo4
+
+# error: [too-many-positional-arguments] "Too many positional arguments to bound method `__init__`: expected 0, got 1"
+reveal_type(Foo4(42))  # revealed: Foo4
+```
+
+### Lookup of `__new__`
+
+The `__new__` method is always invoked on the class itself, never on the metaclass. This is
+different from how other dunder methods like `__lt__` are implicitly called (always on the
+meta-type, never on the type itself).
+
+```py
+from typing_extensions import Literal
+
+class Meta(type):
+    def __new__(mcls, name, bases, namespace, /, **kwargs):
+        return super().__new__(mcls, name, bases, namespace)
+
+    def __lt__(cls, other) -> Literal[True]:
+        return True
+
+class C(metaclass=Meta): ...
+
+# No error is raised here, since we don't implicitly call `Meta.__new__`
+reveal_type(C())  # revealed: C
+
+# Meta.__lt__ is implicitly called here:
+reveal_type(C < C)  # revealed: Literal[True]
+```

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

@@ -205,7 +205,7 @@ reveal_type(IntOrStr.__or__)  # revealed: bound method typing.TypeAliasType.__or
 
 The `__get__` method on `types.FunctionType` has the following overloaded signature in typeshed:
 
-```py
+```pyi
 from types import FunctionType, MethodType
 from typing import overload
 

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

@@ -162,6 +162,44 @@ def _(flag: bool):
     reveal_type(f("string"))  # revealed: Literal["string", "'string'"]
 ```
 
+## Unions with literals and negations
+
+```py
+from typing import Literal
+from knot_extensions import Not, AlwaysFalsy, static_assert, is_subtype_of, is_assignable_to
+
+static_assert(is_subtype_of(Literal["a", ""], Literal["a", ""] | Not[AlwaysFalsy]))
+static_assert(is_subtype_of(Not[AlwaysFalsy], Literal["", "a"] | Not[AlwaysFalsy]))
+static_assert(is_subtype_of(Literal["a", ""], Not[AlwaysFalsy] | Literal["a", ""]))
+static_assert(is_subtype_of(Not[AlwaysFalsy], Not[AlwaysFalsy] | Literal["a", ""]))
+
+static_assert(is_subtype_of(Literal["a", ""], Literal["a", ""] | Not[Literal[""]]))
+static_assert(is_subtype_of(Not[Literal[""]], Literal["a", ""] | Not[Literal[""]]))
+static_assert(is_subtype_of(Literal["a", ""], Not[Literal[""]] | Literal["a", ""]))
+static_assert(is_subtype_of(Not[Literal[""]], Not[Literal[""]] | Literal["a", ""]))
+
+def _(
+    a: Literal["a", ""] | Not[AlwaysFalsy],
+    b: Literal["a", ""] | Not[Literal[""]],
+    c: Literal[""] | Not[Literal[""]],
+    d: Not[Literal[""]] | Literal[""],
+    e: Literal["a"] | Not[Literal["a"]],
+    f: Literal[b"b"] | Not[Literal[b"b"]],
+    g: Not[Literal[b"b"]] | Literal[b"b"],
+    h: Literal[42] | Not[Literal[42]],
+    i: Not[Literal[42]] | Literal[42],
+):
+    reveal_type(a)  # revealed: Literal[""] | ~AlwaysFalsy
+    reveal_type(b)  # revealed: object
+    reveal_type(c)  # revealed: object
+    reveal_type(d)  # revealed: object
+    reveal_type(e)  # revealed: object
+    reveal_type(f)  # revealed: object
+    reveal_type(g)  # revealed: object
+    reveal_type(h)  # revealed: object
+    reveal_type(i)  # revealed: object
+```
+
 ## Cannot use an argument as both a value and a type form
 
 ```py

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

@@ -13,7 +13,7 @@ reveal_type(1 is not 1)  # revealed: bool
 reveal_type(1 is 2)  # revealed: Literal[False]
 reveal_type(1 is not 7)  # revealed: Literal[True]
 # error: [unsupported-operator] "Operator `<=` is not supported for types `int` and `str`, in comparing `Literal[1]` with `Literal[""]`"
-reveal_type(1 <= "" and 0 < 1)  # revealed: Unknown & ~AlwaysTruthy | Literal[True]
+reveal_type(1 <= "" and 0 < 1)  # revealed: (Unknown & ~AlwaysTruthy) | Literal[True]
 ```
 
 ## Integer instance

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

@@ -37,7 +37,7 @@ class C:
         return self
 
 x = A() < B() < C()
-reveal_type(x)  # revealed: A & ~AlwaysTruthy | B
+reveal_type(x)  # revealed: (A & ~AlwaysTruthy) | B
 
 y = 0 < 1 < A() < 3
 reveal_type(y)  # revealed: Literal[False] | A

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

@@ -127,8 +127,9 @@ class AsyncIterable:
     def __aiter__(self) -> AsyncIterator:
         return AsyncIterator()
 
-# revealed: @Todo(async iterables/iterators)
-[reveal_type(x) async for x in AsyncIterable()]
+async def _():
+    # revealed: @Todo(async iterables/iterators)
+    [reveal_type(x) async for x in AsyncIterable()]
 ```
 
 ### Invalid async comprehension
@@ -145,6 +146,7 @@ class Iterable:
     def __iter__(self) -> Iterator:
         return Iterator()
 
-# revealed: @Todo(async iterables/iterators)
-[reveal_type(x) async for x in Iterable()]
+async def _():
+    # revealed: @Todo(async iterables/iterators)
+    [reveal_type(x) async for x in Iterable()]
 ```

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

@@ -42,6 +42,6 @@ def _(flag: bool):
 class NotBoolable:
     __bool__: int = 3
 
-# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
+# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`"
 3 if NotBoolable() else 4
 ```

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

@@ -154,10 +154,10 @@ def _(flag: bool):
 class NotBoolable:
     __bool__: int = 3
 
-# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
+# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`"
 if NotBoolable():
     ...
-# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
+# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`"
 elif NotBoolable():
     ...
 ```

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

@@ -292,7 +292,7 @@ class NotBoolable:
 def _(target: int, flag: NotBoolable):
     y = 1
     match target:
-        # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
+        # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`"
         case 1 if flag:
             y = 2
         case 2:

crates/red_knot_python_semantic/resources/mdtest/dataclass_transform.md

@@ -0,0 +1,293 @@
+# `typing.dataclass_transform`
+
+```toml
+[environment]
+python-version = "3.12"
+```
+
+`dataclass_transform` is a decorator that can be used to let type checkers know that a function,
+class, or metaclass is a `dataclass`-like construct.
+
+## Basic example
+
+```py
+from typing_extensions import dataclass_transform
+
+@dataclass_transform()
+def my_dataclass[T](cls: type[T]) -> type[T]:
+    # modify cls
+    return cls
+
+@my_dataclass
+class Person:
+    name: str
+    age: int | None = None
+
+Person("Alice", 20)
+Person("Bob", None)
+Person("Bob")
+
+# error: [missing-argument]
+Person()
+```
+
+## Decorating decorators that take parameters themselves
+
+If we want our `dataclass`-like decorator to also take parameters, that is also possible:
+
+```py
+from typing_extensions import dataclass_transform, Callable
+
+@dataclass_transform()
+def versioned_class[T](*, version: int = 1):
+    def decorator(cls):
+        # modify cls
+        return cls
+    return decorator
+
+@versioned_class(version=2)
+class Person:
+    name: str
+    age: int | None = None
+
+Person("Alice", 20)
+
+# error: [missing-argument]
+Person()
+```
+
+We properly type-check the arguments to the decorator:
+
+```py
+from typing_extensions import dataclass_transform, Callable
+
+# error: [invalid-argument-type]
+@versioned_class(version="a string")
+class C:
+    name: str
+```
+
+## Types of decorators
+
+The examples from this section are straight from the Python documentation on
+[`typing.dataclass_transform`].
+
+### Decorating a decorator function
+
+```py
+from typing_extensions import dataclass_transform
+
+@dataclass_transform()
+def create_model[T](cls: type[T]) -> type[T]:
+    ...
+    return cls
+
+@create_model
+class CustomerModel:
+    id: int
+    name: str
+
+CustomerModel(id=1, name="Test")
+```
+
+### Decorating a metaclass
+
+```py
+from typing_extensions import dataclass_transform
+
+@dataclass_transform()
+class ModelMeta(type): ...
+
+class ModelBase(metaclass=ModelMeta): ...
+
+class CustomerModel(ModelBase):
+    id: int
+    name: str
+
+CustomerModel(id=1, name="Test")
+
+# error: [missing-argument]
+CustomerModel()
+```
+
+### Decorating a base class
+
+```py
+from typing_extensions import dataclass_transform
+
+@dataclass_transform()
+class ModelBase: ...
+
+class CustomerModel(ModelBase):
+    id: int
+    name: str
+
+# TODO: this is not supported yet
+# error: [unknown-argument]
+# error: [unknown-argument]
+CustomerModel(id=1, name="Test")
+```
+
+## Arguments to `dataclass_transform`
+
+### `eq_default`
+
+`eq=True/False` does not have a observable effect (apart from a minor change regarding whether
+`other` is positional-only or not, which is not modelled at the moment).
+
+### `order_default`
+
+The `order_default` argument controls whether methods such as `__lt__` are generated by default.
+This can be overwritten using the `order` argument to the custom decorator:
+
+```py
+from typing_extensions import dataclass_transform
+
+@dataclass_transform()
+def normal(*, order: bool = False):
+    raise NotImplementedError
+
+@dataclass_transform(order_default=False)
+def order_default_false(*, order: bool = False):
+    raise NotImplementedError
+
+@dataclass_transform(order_default=True)
+def order_default_true(*, order: bool = True):
+    raise NotImplementedError
+
+@normal
+class Normal:
+    inner: int
+
+Normal(1) < Normal(2)  # error: [unsupported-operator]
+
+@normal(order=True)
+class NormalOverwritten:
+    inner: int
+
+NormalOverwritten(1) < NormalOverwritten(2)
+
+@order_default_false
+class OrderFalse:
+    inner: int
+
+OrderFalse(1) < OrderFalse(2)  # error: [unsupported-operator]
+
+@order_default_false(order=True)
+class OrderFalseOverwritten:
+    inner: int
+
+OrderFalseOverwritten(1) < OrderFalseOverwritten(2)
+
+@order_default_true
+class OrderTrue:
+    inner: int
+
+OrderTrue(1) < OrderTrue(2)
+
+@order_default_true(order=False)
+class OrderTrueOverwritten:
+    inner: int
+
+# error: [unsupported-operator]
+OrderTrueOverwritten(1) < OrderTrueOverwritten(2)
+```
+
+### `kw_only_default`
+
+To do
+
+### `field_specifiers`
+
+To do
+
+## Overloaded dataclass-like decorators
+
+In the case of an overloaded decorator, the `dataclass_transform` decorator can be applied to the
+implementation, or to *one* of the overloads.
+
+### Applying `dataclass_transform` to the implementation
+
+```py
+from typing_extensions import dataclass_transform, TypeVar, Callable, overload
+
+T = TypeVar("T", bound=type)
+
+@overload
+def versioned_class(
+    cls: T,
+    *,
+    version: int = 1,
+) -> T: ...
+@overload
+def versioned_class(
+    *,
+    version: int = 1,
+) -> Callable[[T], T]: ...
+@dataclass_transform()
+def versioned_class(
+    cls: T | None = None,
+    *,
+    version: int = 1,
+) -> T | Callable[[T], T]:
+    raise NotImplementedError
+
+@versioned_class
+class D1:
+    x: str
+
+@versioned_class(version=2)
+class D2:
+    x: str
+
+D1("a")
+D2("a")
+
+D1(1.2)  # error: [invalid-argument-type]
+D2(1.2)  # error: [invalid-argument-type]
+```
+
+### Applying `dataclass_transform` to an overload
+
+```py
+from typing_extensions import dataclass_transform, TypeVar, Callable, overload
+
+T = TypeVar("T", bound=type)
+
+@overload
+@dataclass_transform()
+def versioned_class(
+    cls: T,
+    *,
+    version: int = 1,
+) -> T: ...
+@overload
+def versioned_class(
+    *,
+    version: int = 1,
+) -> Callable[[T], T]: ...
+def versioned_class(
+    cls: T | None = None,
+    *,
+    version: int = 1,
+) -> T | Callable[[T], T]:
+    raise NotImplementedError
+
+@versioned_class
+class D1:
+    x: str
+
+@versioned_class(version=2)
+class D2:
+    x: str
+
+# TODO: these should not be errors
+D1("a")  # error: [too-many-positional-arguments]
+D2("a")  # error: [too-many-positional-arguments]
+
+# TODO: these should be invalid-argument-type errors
+D1(1.2)  # error: [too-many-positional-arguments]
+D2(1.2)  # error: [too-many-positional-arguments]
+```
+
+[`typing.dataclass_transform`]: https://docs.python.org/3/library/typing.html#typing.dataclass_transform

crates/red_knot_python_semantic/resources/mdtest/dataclasses.md

@@ -689,7 +689,7 @@ from dataclasses import dataclass
 
 dataclass_with_order = dataclass(order=True)
 
-reveal_type(dataclass_with_order)  # revealed: <decorator produced by dataclasses.dataclass>
+reveal_type(dataclass_with_order)  # revealed: <decorator produced by dataclass-like function>
 
 @dataclass_with_order
 class C:

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

@@ -0,0 +1,221 @@
+# Semantic syntax error diagnostics
+
+## `async` comprehensions in synchronous comprehensions
+
+### Python 3.10
+
+<!-- snapshot-diagnostics -->
+
+Before Python 3.11, `async` comprehensions could not be used within outer sync comprehensions, even
+within an `async` function ([CPython issue](https://github.com/python/cpython/issues/77527)):
+
+```toml
+[environment]
+python-version = "3.10"
+```
+
+```py
+async def elements(n):
+    yield n
+
+async def f():
+    # error: 19 [invalid-syntax] "cannot use an asynchronous comprehension inside of a synchronous comprehension on Python 3.10 (syntax was added in 3.11)"
+    return {n: [x async for x in elements(n)] for n in range(3)}
+```
+
+If all of the comprehensions are `async`, on the other hand, the code was still valid:
+
+```py
+async def test():
+    return [[x async for x in elements(n)] async for n in range(3)]
+```
+
+These are a couple of tricky but valid cases to check that nested scope handling is wired up
+correctly in the `SemanticSyntaxContext` trait:
+
+```py
+async def f():
+    [x for x in [1]] and [x async for x in elements(1)]
+
+async def f():
+    def g():
+        pass
+    [x async for x in elements(1)]
+```
+
+### Python 3.11
+
+All of these same examples are valid after Python 3.11:
+
+```toml
+[environment]
+python-version = "3.11"
+```
+
+```py
+async def elements(n):
+    yield n
+
+async def f():
+    return {n: [x async for x in elements(n)] for n in range(3)}
+```
+
+## Late `__future__` import
+
+```py
+from collections import namedtuple
+
+# error: [invalid-syntax] "__future__ imports must be at the top of the file"
+from __future__ import print_function
+```
+
+## Invalid annotation
+
+This one might be a bit redundant with the `invalid-type-form` error.
+
+```toml
+[environment]
+python-version = "3.12"
+```
+
+```py
+from __future__ import annotations
+
+# error: [invalid-type-form] "Named expressions are not allowed in type expressions"
+# error: [invalid-syntax] "named expression cannot be used within a type annotation"
+def f() -> (y := 3): ...
+```
+
+## Duplicate `match` key
+
+```toml
+[environment]
+python-version = "3.10"
+```
+
+```py
+match 2:
+    # error: [invalid-syntax] "mapping pattern checks duplicate key `"x"`"
+    case {"x": 1, "x": 2}:
+        ...
+```
+
+## `return`, `yield`, `yield from`, and `await` outside function
+
+```py
+# error: [invalid-syntax] "`return` statement outside of a function"
+return
+
+# error: [invalid-syntax] "`yield` statement outside of a function"
+yield
+
+# error: [invalid-syntax] "`yield from` statement outside of a function"
+yield from []
+
+# error: [invalid-syntax] "`await` statement outside of a function"
+# error: [invalid-syntax] "`await` outside of an asynchronous function"
+await 1
+
+def f():
+    # error: [invalid-syntax] "`await` outside of an asynchronous function"
+    await 1
+```
+
+Generators are evaluated lazily, so `await` is allowed, even outside of a function.
+
+```py
+async def g():
+    yield 1
+
+(x async for x in g())
+```
+
+## Rebound comprehension variable
+
+Walrus operators cannot rebind variables already in use as iterators:
+
+```py
+# error: [invalid-syntax] "assignment expression cannot rebind comprehension variable"
+[x := 2 for x in range(10)]
+
+# error: [invalid-syntax] "assignment expression cannot rebind comprehension variable"
+{y := 5 for y in range(10)}
+```
+
+## Multiple case assignments
+
+Variable names in pattern matching must be unique within a single pattern:
+
+```toml
+[environment]
+python-version = "3.10"
+```
+
+```py
+x = [1, 2]
+match x:
+    # error: [invalid-syntax] "multiple assignments to name `a` in pattern"
+    case [a, a]:
+        pass
+    case _:
+        pass
+
+d = {"key": "value"}
+match d:
+    # error: [invalid-syntax] "multiple assignments to name `b` in pattern"
+    case {"key": b, "other": b}:
+        pass
+```
+
+## Duplicate type parameter
+
+Type parameter names must be unique in a generic class or function definition:
+
+```toml
+[environment]
+python-version = "3.12"
+```
+
+```py
+# error: [invalid-syntax] "duplicate type parameter"
+class C[T, T]:
+    pass
+
+# error: [invalid-syntax] "duplicate type parameter"
+def f[X, Y, X]():
+    pass
+```
+
+## `await` outside async function
+
+This error includes `await`, `async for`, `async with`, and `async` comprehensions.
+
+```python
+async def elements(n):
+    yield n
+
+def _():
+    # error: [invalid-syntax] "`await` outside of an asynchronous function"
+    await 1
+    # error: [invalid-syntax] "`async for` outside of an asynchronous function"
+    async for _ in elements(1):
+        ...
+    # error: [invalid-syntax] "`async with` outside of an asynchronous function"
+    async with elements(1) as x:
+        ...
+    # error: [invalid-syntax] "cannot use an asynchronous comprehension outside of an asynchronous function on Python 3.9 (syntax was added in 3.11)"
+    # error: [invalid-syntax] "asynchronous comprehension outside of an asynchronous function"
+    [x async for x in elements(1)]
+```
+
+## Load before `global` declaration
+
+This should be an error, but it's not yet.
+
+TODO implement `SemanticSyntaxContext::global`
+
+```py
+def f():
+    x = 1
+    global x
+```

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

@@ -0,0 +1,19 @@
+# Shadowing
+
+<!-- snapshot-diagnostics -->
+
+## Implicit class shadowing
+
+```py
+class C: ...
+
+C = 1  # error: [invalid-assignment]
+```
+
+## Implicit function shadowing
+
+```py
+def f(): ...
+
+f = 1  # error: [invalid-assignment]
+```

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

@@ -8,14 +8,20 @@
 a, b = 1  # error: [not-iterable]
 ```
 
-## Too many values to unpack
+## Exactly too many values to unpack
 
 ```py
 a, b = (1, 2, 3)  # error: [invalid-assignment]
 ```
 
-## Too few values to unpack
+## Exactly too few values to unpack
 
 ```py
 a, b = (1,)  # error: [invalid-assignment]
 ```
+
+## Too few values to unpack
+
+```py
+[a, *b, c, d] = (1, 2)  # error: [invalid-assignment]
+```

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

@@ -0,0 +1,61 @@
+<!-- snapshot-diagnostics -->
+
+# Different ways that `unsupported-bool-conversion` can occur
+
+## Has a `__bool__` method, but has incorrect parameters
+
+```py
+class NotBoolable:
+    def __bool__(self, foo):
+        return False
+
+a = NotBoolable()
+
+# error: [unsupported-bool-conversion]
+10 and a and True
+```
+
+## Has a `__bool__` method, but has an incorrect return type
+
+```py
+class NotBoolable:
+    def __bool__(self) -> str:
+        return "wat"
+
+a = NotBoolable()
+
+# error: [unsupported-bool-conversion]
+10 and a and True
+```
+
+## Has a `__bool__` attribute, but it's not callable
+
+```py
+class NotBoolable:
+    __bool__: int = 3
+
+a = NotBoolable()
+
+# error: [unsupported-bool-conversion]
+10 and a and True
+```
+
+## Part of a union where at least one member has incorrect `__bool__` method
+
+```py
+class NotBoolable1:
+    def __bool__(self) -> str:
+        return "wat"
+
+class NotBoolable2:
+    pass
+
+class NotBoolable3:
+    __bool__: int = 3
+
+def get() -> NotBoolable1 | NotBoolable2 | NotBoolable3:
+    return NotBoolable2()
+
+# error: [unsupported-bool-conversion]
+10 and get() and True
+```

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

@@ -4,6 +4,6 @@
 class NotBoolable:
     __bool__: int = 3
 
-# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
+# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`"
 assert NotBoolable()
 ```

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

@@ -10,8 +10,8 @@ def _(foo: str):
     reveal_type(False or "z")  # revealed: Literal["z"]
     reveal_type(False or True)  # revealed: Literal[True]
     reveal_type(False or False)  # revealed: Literal[False]
-    reveal_type(foo or False)  # revealed: str & ~AlwaysFalsy | Literal[False]
-    reveal_type(foo or True)  # revealed: str & ~AlwaysFalsy | Literal[True]
+    reveal_type(foo or False)  # revealed: (str & ~AlwaysFalsy) | Literal[False]
+    reveal_type(foo or True)  # revealed: (str & ~AlwaysFalsy) | Literal[True]
 ```
 
 ## AND
@@ -20,8 +20,8 @@ def _(foo: str):
 def _(foo: str):
     reveal_type(True and False)  # revealed: Literal[False]
     reveal_type(False and True)  # revealed: Literal[False]
-    reveal_type(foo and False)  # revealed: str & ~AlwaysTruthy | Literal[False]
-    reveal_type(foo and True)  # revealed: str & ~AlwaysTruthy | Literal[True]
+    reveal_type(foo and False)  # revealed: (str & ~AlwaysTruthy) | Literal[False]
+    reveal_type(foo and True)  # revealed: (str & ~AlwaysTruthy) | Literal[True]
     reveal_type("x" and "y" and "z")  # revealed: Literal["z"]
     reveal_type("x" and "y" and "")  # revealed: Literal[""]
     reveal_type("" and "y")  # revealed: Literal[""]
@@ -123,7 +123,7 @@ if NotBoolable():
 class NotBoolable:
     __bool__: None = None
 
-# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
+# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`"
 if NotBoolable():
     ...
 ```
@@ -135,7 +135,7 @@ def test(cond: bool):
     class NotBoolable:
         __bool__: int | None = None if cond else 3
 
-    # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
+    # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`"
     if NotBoolable():
         ...
 ```
@@ -149,7 +149,7 @@ def test(cond: bool):
 
     a = 10 if cond else NotBoolable()
 
-    # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `Literal[10] | NotBoolable`; its `__bool__` method isn't callable"
+    # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `Literal[10] | NotBoolable`"
     if a:
         ...
 ```

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

@@ -203,7 +203,7 @@ from typing import TypeVar
 
 T = TypeVar("T")
 
-# TODO: `invalid-return-type` error should be emitted
+# error: [invalid-return-type]
 def m(x: T) -> T: ...
 ```
 

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

@@ -232,21 +232,11 @@ TODO: These do not currently work yet, because we don't correctly model the nest
 class C[T]:
     def __init__[S](self, x: T, y: S) -> None: ...
 
-# TODO: no error
-# TODO: revealed: C[Literal[1]]
-# error: [invalid-argument-type]
-reveal_type(C(1, 1))  # revealed: C[Unknown]
-# TODO: no error
-# TODO: revealed: C[Literal[1]]
-# error: [invalid-argument-type]
-reveal_type(C(1, "string"))  # revealed: C[Unknown]
-# TODO: no error
-# TODO: revealed: C[Literal[1]]
-# error: [invalid-argument-type]
-reveal_type(C(1, True))  # revealed: C[Unknown]
+reveal_type(C(1, 1))  # revealed: C[Literal[1]]
+reveal_type(C(1, "string"))  # revealed: C[Literal[1]]
+reveal_type(C(1, True))  # revealed: C[Literal[1]]
 
-# TODO: [invalid-assignment] "Object of type `C[Literal["five"]]` is not assignable to `C[int]`"
-# error: [invalid-argument-type] "Argument to this function is incorrect: Expected `S`, found `Literal[1]`"
+# error: [invalid-assignment] "Object of type `C[Literal["five"]]` is not assignable to `C[int]`"
 wrong_innards: C[int] = C("five", 1)
 ```
 
@@ -285,14 +275,16 @@ c: C[int] = C[int]()
 reveal_type(c.method("string"))  # revealed: Literal["string"]
 ```
 
-## Cyclic class definition
+## Cyclic class definitions
+
+### F-bounded quantification
 
 A class can use itself as the type parameter of one of its superclasses. (This is also known as the
 [curiously recurring template pattern][crtp] or [F-bounded quantification][f-bound].)
 
-Here, `Sub` is not a generic class, since it fills its superclass's type parameter (with itself).
+#### In a stub file
 
-`stub.pyi`:
+Here, `Sub` is not a generic class, since it fills its superclass's type parameter (with itself).
 
 ```pyi
 class Base[T]: ...
@@ -301,9 +293,9 @@ class Sub(Base[Sub]): ...
 reveal_type(Sub)  # revealed: Literal[Sub]
 ```
 
-A similar case can work in a non-stub file, if forward references are stringified:
+#### With string forward references
 
-`string_annotation.py`:
+A similar case can work in a non-stub file, if forward references are stringified:
 
 ```py
 class Base[T]: ...
@@ -312,9 +304,9 @@ class Sub(Base["Sub"]): ...
 reveal_type(Sub)  # revealed: Literal[Sub]
 ```
 
-In a non-stub file, without stringified forward references, this raises a `NameError`:
+#### Without string forward references
 
-`bare_annotation.py`:
+In a non-stub file, without stringified forward references, this raises a `NameError`:
 
 ```py
 class Base[T]: ...
@@ -323,13 +315,23 @@ class Base[T]: ...
 class Sub(Base[Sub]): ...
 ```
 
-## Another cyclic case
+### Cyclic inheritance as a generic parameter
 
 ```pyi
-# TODO no error (generics)
-# error: [invalid-base]
 class Derived[T](list[Derived[T]]): ...
 ```
 
+### Direct cyclic inheritance
+
+Inheritance that would result in a cyclic MRO is detected as an error.
+
+```py
+# error: [cyclic-class-definition]
+class C[T](C): ...
+
+# error: [cyclic-class-definition]
+class D[T](D[int]): ...
+```
+
 [crtp]: https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern
 [f-bound]: https://en.wikipedia.org/wiki/Bounded_quantification#F-bounded_quantification

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

@@ -71,6 +71,39 @@ def f[T](x: list[T]) -> T:
 reveal_type(f([1.0, 2.0]))  # revealed: Unknown
 ```
 
+## Inferring a bound typevar
+
+<!-- snapshot-diagnostics -->
+
+```py
+from typing_extensions import reveal_type
+
+def f[T: int](x: T) -> T:
+    return x
+
+reveal_type(f(1))  # revealed: Literal[1]
+reveal_type(f(True))  # revealed: Literal[True]
+# error: [invalid-argument-type] "Argument to this function is incorrect: Argument type `Literal["string"]` does not satisfy upper bound of type variable `T`"
+reveal_type(f("string"))  # revealed: Unknown
+```
+
+## Inferring a constrained typevar
+
+<!-- snapshot-diagnostics -->
+
+```py
+from typing_extensions import reveal_type
+
+def f[T: (int, None)](x: T) -> T:
+    return x
+
+reveal_type(f(1))  # revealed: int
+reveal_type(f(True))  # revealed: int
+reveal_type(f(None))  # revealed: None
+# error: [invalid-argument-type] "Argument to this function is incorrect: Argument type `Literal["string"]` does not satisfy constraints of type variable `T`"
+reveal_type(f("string"))  # revealed: Unknown
+```
+
 ## Typevar constraints
 
 If a type parameter has an upper bound, that upper bound constrains which types can be used for that

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

@@ -19,6 +19,9 @@ in newer Python releases.
 from typing import TypeVar
 
 T = TypeVar("T")
+reveal_type(type(T))  # revealed: Literal[TypeVar]
+reveal_type(T)  # revealed: typing.TypeVar
+reveal_type(T.__name__)  # revealed: Literal["T"]
 ```
 
 ### Directly assigned to a variable
@@ -29,7 +32,12 @@ T = TypeVar("T")
 ```py
 from typing import TypeVar
 
-# TODO: error
+T = TypeVar("T")
+# TODO: no error
+# error: [invalid-legacy-type-variable]
+U: TypeVar = TypeVar("U")
+
+# error: [invalid-legacy-type-variable] "A legacy `typing.TypeVar` must be immediately assigned to a variable"
 TestList = list[TypeVar("W")]
 ```
 
@@ -40,7 +48,7 @@ TestList = list[TypeVar("W")]
 ```py
 from typing import TypeVar
 
-# TODO: error
+# error: [invalid-legacy-type-variable] "The name of a legacy `typing.TypeVar` (`Q`) must match the name of the variable it is assigned to (`T`)"
 T = TypeVar("Q")
 ```
 
@@ -57,6 +65,52 @@ T = TypeVar("T")
 T = TypeVar("T")
 ```
 
+### Type variables with a default
+
+Note that the `__default__` property is only available in Python ≥3.13.
+
+```toml
+[environment]
+python-version = "3.13"
+```
+
+```py
+from typing import TypeVar
+
+T = TypeVar("T", default=int)
+reveal_type(T.__default__)  # revealed: int
+reveal_type(T.__bound__)  # revealed: None
+reveal_type(T.__constraints__)  # revealed: tuple[()]
+
+S = TypeVar("S")
+reveal_type(S.__default__)  # revealed: NoDefault
+```
+
+### Type variables with an upper bound
+
+```py
+from typing import TypeVar
+
+T = TypeVar("T", bound=int)
+reveal_type(T.__bound__)  # revealed: int
+reveal_type(T.__constraints__)  # revealed: tuple[()]
+
+S = TypeVar("S")
+reveal_type(S.__bound__)  # revealed: None
+```
+
+### Type variables with constraints
+
+```py
+from typing import TypeVar
+
+T = TypeVar("T", int, str)
+reveal_type(T.__constraints__)  # revealed: tuple[int, str]
+
+S = TypeVar("S")
+reveal_type(S.__constraints__)  # revealed: tuple[()]
+```
+
 ### Cannot have only one constraint
 
 > `TypeVar` supports constraining parametric types to a fixed set of possible types...There should

crates/red_knot_python_semantic/resources/mdtest/generics/pep695.md

@@ -17,10 +17,51 @@ instances of `typing.TypeVar`, just like legacy type variables.
 ```py
 def f[T]():
     reveal_type(type(T))  # revealed: Literal[TypeVar]
-    reveal_type(T)  # revealed: T
+    reveal_type(T)  # revealed: typing.TypeVar
     reveal_type(T.__name__)  # revealed: Literal["T"]
 ```
 
+### Type variables with a default
+
+Note that the `__default__` property is only available in Python ≥3.13.
+
+```toml
+[environment]
+python-version = "3.13"
+```
+
+```py
+def f[T = int]():
+    reveal_type(T.__default__)  # revealed: int
+    reveal_type(T.__bound__)  # revealed: None
+    reveal_type(T.__constraints__)  # revealed: tuple[()]
+
+def g[S]():
+    reveal_type(S.__default__)  # revealed: NoDefault
+```
+
+### Type variables with an upper bound
+
+```py
+def f[T: int]():
+    reveal_type(T.__bound__)  # revealed: int
+    reveal_type(T.__constraints__)  # revealed: tuple[()]
+
+def g[S]():
+    reveal_type(S.__bound__)  # revealed: None
+```
+
+### Type variables with constraints
+
+```py
+def f[T: (int, str)]():
+    reveal_type(T.__constraints__)  # revealed: tuple[int, str]
+    reveal_type(T.__bound__)  # revealed: None
+
+def g[S]():
+    reveal_type(S.__constraints__)  # revealed: tuple[()]
+```
+
 ### Cannot have only one constraint
 
 > `TypeVar` supports constraining parametric types to a fixed set of possible types...There should

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

@@ -142,8 +142,7 @@ class Legacy(Generic[T]):
         return y
 
 legacy: Legacy[int] = Legacy()
-# TODO: revealed: str
-reveal_type(legacy.m(1, "string"))  # revealed: @Todo(Support for `typing.TypeVar` instances in type expressions)
+reveal_type(legacy.m(1, "string"))  # revealed: Literal["string"]
 ```
 
 With PEP 695 syntax, it is clearer that the method uses a separate typevar:

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

@@ -7,7 +7,7 @@ Builtin symbols can be explicitly imported:
 ```py
 import builtins
 
-reveal_type(builtins.chr)  # revealed: def chr(i: int | SupportsIndex, /) -> str
+reveal_type(builtins.chr)  # revealed: def chr(i: SupportsIndex, /) -> str
 ```
 
 ## Implicit use of builtin
@@ -15,7 +15,7 @@ reveal_type(builtins.chr)  # revealed: def chr(i: int | SupportsIndex, /) -> str
 Or used implicitly:
 
 ```py
-reveal_type(chr)  # revealed: def chr(i: int | SupportsIndex, /) -> str
+reveal_type(chr)  # revealed: def chr(i: SupportsIndex, /) -> str
 reveal_type(str)  # revealed: Literal[str]
 ```
 

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

@@ -189,7 +189,7 @@ match 42:
         ...
     case [O]:
         ...
-    case P | Q:
+    case P | Q:  # error: [invalid-syntax] "name capture `P` makes remaining patterns unreachable"
         ...
     case object(foo=R):
         ...
@@ -289,7 +289,7 @@ match 42:
         ...
     case [D]:
         ...
-    case E | F:
+    case E | F:  # error: [invalid-syntax] "name capture `E` makes remaining patterns unreachable"
         ...
     case object(foo=G):
         ...
@@ -357,7 +357,7 @@ match 42:
         ...
     case [D]:
         ...
-    case E | F:
+    case E | F:  # error: [invalid-syntax] "name capture `E` makes remaining patterns unreachable"
         ...
     case object(foo=G):
         ...

crates/red_knot_python_semantic/resources/mdtest/intersection_types.md

@@ -191,9 +191,9 @@ def _(
     i2: Intersection[P | Q | R, S],
     i3: Intersection[P | Q, R | S],
 ) -> None:
-    reveal_type(i1)  # revealed: P & Q | P & R | P & S
-    reveal_type(i2)  # revealed: P & S | Q & S | R & S
-    reveal_type(i3)  # revealed: P & R | Q & R | P & S | Q & S
+    reveal_type(i1)  # revealed: (P & Q) | (P & R) | (P & S)
+    reveal_type(i2)  # revealed: (P & S) | (Q & S) | (R & S)
+    reveal_type(i3)  # revealed: (P & R) | (Q & R) | (P & S) | (Q & S)
 
 def simplifications_for_same_elements(
     i1: Intersection[P, Q | P],
@@ -216,7 +216,7 @@ def simplifications_for_same_elements(
     # = P & Q | P & R | Q | Q & R
     # = Q | P & R
     # (again, because Q is a supertype of P & Q and of Q & R)
-    reveal_type(i3)  # revealed: Q | P & R
+    reveal_type(i3)  # revealed: Q | (P & R)
 
     #   (P | Q) & (P | Q)
     # = P & P | P & Q | Q & P | Q & Q

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

@@ -286,7 +286,7 @@ class Test:
     def __iter__(self) -> TestIter | int:
         return TestIter()
 
-# error: [not-iterable] "Object of type `Test` may not be iterable because its `__iter__` method returns an object of type `TestIter | int`, which may not have a `__next__` method"
+# error: [not-iterable] "Object of type `Test` may not be iterable"
 for x in Test():
     reveal_type(x)  # revealed: int
 ```
@@ -316,12 +316,12 @@ def _(flag: bool):
         else:
             __iter__: None = None
 
-    # error: [not-iterable] "Object of type `Iterable1` may not be iterable because its `__iter__` attribute (with type `CustomCallable`) may not be callable"
+    # error: [not-iterable] "Object of type `Iterable1` may not be iterable"
     for x in Iterable1():
         # TODO... `int` might be ideal here?
         reveal_type(x)  # revealed: int | Unknown
 
-    # error: [not-iterable] "Object of type `Iterable2` may not be iterable because its `__iter__` attribute (with type `(bound method Iterable2.__iter__() -> Iterator) | None`) may not be callable"
+    # error: [not-iterable] "Object of type `Iterable2` may not be iterable"
     for y in Iterable2():
         # TODO... `int` might be ideal here?
         reveal_type(y)  # revealed: int | Unknown
@@ -376,7 +376,7 @@ def _(flag: bool):
         def __iter__(self) -> Iterator:
             return Iterator()
 
-    # error: [not-iterable] "Object of type `Iterable` may not be iterable because its `__iter__` method returns an object of type `Iterator`, which may not have a `__next__` method"
+    # error: [not-iterable] "Object of type `Iterable` may not be iterable"
     for x in Iterable():
         reveal_type(x)  # revealed: int
 ```
@@ -461,7 +461,7 @@ def _(flag: bool):
                 return Iterator()
         __getitem__: None = None
 
-    # error: [not-iterable] "Object of type `Iterable` may not be iterable because it may not have an `__iter__` method and its `__getitem__` attribute has type `None`, which is not callable"
+    # error: [not-iterable] "Object of type `Iterable` may not be iterable"
     for x in Iterable():
         reveal_type(x)  # revealed: int
 ```

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

@@ -123,7 +123,7 @@ def _(flag: bool, flag2: bool):
 class NotBoolable:
     __bool__: int = 3
 
-# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
+# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`"
 while NotBoolable():
     ...
 ```

crates/red_knot_python_semantic/resources/mdtest/mdtest_custom_typeshed.md

@@ -22,6 +22,7 @@ We can then place custom stub files in `/typeshed/stdlib`, for example:
 `/typeshed/stdlib/builtins.pyi`:
 
 ```pyi
+class object: ...
 class BuiltinClass: ...
 
 builtin_symbol: BuiltinClass

crates/red_knot_python_semantic/resources/mdtest/metaclass.md

@@ -53,6 +53,25 @@ class B(A): ...
 reveal_type(B.__class__)  # revealed: Literal[M]
 ```
 
+## Linear inheritance with PEP 695 generic class
+
+The same is true if the base with the metaclass is a generic class.
+
+```toml
+[environment]
+python-version = "3.13"
+```
+
+```py
+class M(type): ...
+class A[T](metaclass=M): ...
+class B(A): ...
+class C(A[int]): ...
+
+reveal_type(B.__class__)  # revealed: Literal[M]
+reveal_type(C.__class__)  # revealed: Literal[M]
+```
+
 ## Conflict (1)
 
 The metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its

crates/red_knot_python_semantic/resources/mdtest/mro.md

@@ -191,8 +191,8 @@ reveal_type(AA.__mro__)  # revealed: tuple[Literal[AA], Literal[Z], Unknown, Lit
 
 ## `__bases__` includes a `Union`
 
-We don't support union types in a class's bases; a base must resolve to a single `ClassLiteralType`.
-If we find a union type in a class's bases, we infer the class's `__mro__` as being
+We don't support union types in a class's bases; a base must resolve to a single `ClassType`. If we
+find a union type in a class's bases, we infer the class's `__mro__` as being
 `[<class>, Unknown, object]`, the same as for MROs that cause errors at runtime.
 
 ```py

crates/red_knot_python_semantic/resources/mdtest/named_tuple.md

@@ -0,0 +1,120 @@
+# `NamedTuple`
+
+`NamedTuple` is a type-safe way to define named tuples — a tuple where each field can be accessed by
+name, and not just by its numeric position within the tuple:
+
+## `typing.NamedTuple`
+
+### Basics
+
+```py
+from typing import NamedTuple
+
+class Person(NamedTuple):
+    id: int
+    name: str
+    age: int | None = None
+
+alice = Person(1, "Alice", 42)
+alice = Person(id=1, name="Alice", age=42)
+bob = Person(2, "Bob")
+bob = Person(id=2, name="Bob")
+
+reveal_type(alice.id)  # revealed: int
+reveal_type(alice.name)  # revealed: str
+reveal_type(alice.age)  # revealed: int | None
+
+# TODO: These should reveal the types of the fields
+reveal_type(alice[0])  # revealed: Unknown
+reveal_type(alice[1])  # revealed: Unknown
+reveal_type(alice[2])  # revealed: Unknown
+
+# error: [missing-argument]
+Person(3)
+
+# error: [too-many-positional-arguments]
+Person(3, "Eve", 99, "extra")
+
+# error: [invalid-argument-type]
+Person(id="3", name="Eve")
+```
+
+Alternative functional syntax:
+
+```py
+Person2 = NamedTuple("Person", [("id", int), ("name", str)])
+alice2 = Person2(1, "Alice")
+
+# TODO: should be an error
+Person2(1)
+
+reveal_type(alice2.id)  # revealed: @Todo(GenericAlias instance)
+reveal_type(alice2.name)  # revealed: @Todo(GenericAlias instance)
+```
+
+### Multiple Inheritance
+
+Multiple inheritance is not supported for `NamedTuple` classes:
+
+```py
+from typing import NamedTuple
+
+# This should ideally emit a diagnostic
+class C(NamedTuple, object):
+    id: int
+    name: str
+```
+
+### Inheriting from a `NamedTuple`
+
+Inheriting from a `NamedTuple` is supported, but new fields on the subclass will not be part of the
+synthesized `__new__` signature:
+
+```py
+from typing import NamedTuple
+
+class User(NamedTuple):
+    id: int
+    name: str
+
+class SuperUser(User):
+    level: int
+
+# This is fine:
+alice = SuperUser(1, "Alice")
+reveal_type(alice.level)  # revealed: int
+
+# This is an error because `level` is not part of the signature:
+# error: [too-many-positional-arguments]
+alice = SuperUser(1, "Alice", 3)
+```
+
+### Generic named tuples
+
+```toml
+[environment]
+python-version = "3.12"
+```
+
+```py
+from typing import NamedTuple
+
+class Property[T](NamedTuple):
+    name: str
+    value: T
+
+# TODO: this should be supported (no error, revealed type of `Property[float]`)
+# error: [invalid-argument-type]
+reveal_type(Property("height", 3.4))  # revealed: Property[Unknown]
+```
+
+## `collections.namedtuple`
+
+```py
+from collections import namedtuple
+
+Person = namedtuple("Person", ["id", "name", "age"], defaults=[None])
+
+alice = Person(1, "Alice", 42)
+bob = Person(2, "Bob")
+```

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

@@ -29,7 +29,7 @@ def _(x: Literal[1, 2, 3], y: Literal[1, 2, 3]):
     assert x is 2
     reveal_type(x)  # revealed: Literal[2]
     assert y == 2
-    reveal_type(y)  # revealed: Literal[1, 2, 3]
+    reveal_type(y)  # revealed: Literal[2]
 ```
 
 ## `assert` with `isinstance`
@@ -51,3 +51,64 @@ def _(x: Literal[1, 2, 3], y: Literal[1, 2, 3]):
     assert y not in (1, 2)
     reveal_type(y)  # revealed: Literal[3]
 ```
+
+## Assertions with messages
+
+```py
+def _(x: int | None, y: int | None):
+    reveal_type(x)  # revealed: int | None
+    assert x is None, reveal_type(x)  # revealed: int
+    reveal_type(x)  # revealed: None
+
+    reveal_type(y)  # revealed: int | None
+    assert isinstance(y, int), reveal_type(y)  # revealed: None
+    reveal_type(y)  # revealed: int
+```
+
+## Assertions with definitions inside the message
+
+```py
+def one(x: int | None):
+    assert x is None, (y := x * 42) * reveal_type(y)  # revealed: int
+
+    # error: [unresolved-reference]
+    reveal_type(y)  # revealed: Unknown
+
+def two(x: int | None, y: int | None):
+    assert x is None, (y := 42) * reveal_type(y)  # revealed: Literal[42]
+    reveal_type(y)  # revealed: int | None
+```
+
+## Assertions with `test` predicates that are statically known to always be `True`
+
+```py
+assert True, (x := 1)
+
+# error: [unresolved-reference]
+reveal_type(x)  # revealed: Unknown
+
+assert False, (y := 1)
+
+# The `assert` statement is terminal if `test` resolves to `False`,
+# so even though we know the `msg` branch will have been taken here
+# (we know what the truthiness of `False is!), we also know that the
+# `y` definition is not visible from this point in control flow
+# (because this point in control flow is unreachable).
+# We make sure that this does not emit an `[unresolved-reference]`
+# diagnostic by adding a reachability constraint,
+# but the inferred type is `Unknown`.
+#
+reveal_type(y)  # revealed: Unknown
+```
+
+## Assertions with messages that reference definitions from the `test`
+
+```py
+def one(x: int | None):
+    assert (y := x), reveal_type(y)  # revealed: (int & ~AlwaysTruthy) | None
+    reveal_type(y)  # revealed: int & ~AlwaysFalsy
+
+def two(x: int | None):
+    assert isinstance((y := x), int), reveal_type(y)  # revealed: None
+    reveal_type(y)  # revealed: int
+```

crates/red_knot_python_semantic/resources/mdtest/narrow/conditionals/boolean.md

@@ -10,7 +10,7 @@ def _(x: A | B):
     if isinstance(x, A) and isinstance(x, B):
         reveal_type(x)  # revealed:  A & B
     else:
-        reveal_type(x)  # revealed:  B & ~A | A & ~B
+        reveal_type(x)  # revealed:  (B & ~A) | (A & ~B)
 ```
 
 ## Arms might not add narrowing constraints
@@ -131,8 +131,8 @@ def _(x: A | B | C, y: A | B | C):
         # The same for `y`
         reveal_type(y)  # revealed:  A | B | C
     else:
-        reveal_type(x)  # revealed:  B & ~A | C & ~A
-        reveal_type(y)  # revealed:  B & ~A | C & ~A
+        reveal_type(x)  # revealed:  (B & ~A) | (C & ~A)
+        reveal_type(y)  # revealed:  (B & ~A) | (C & ~A)
 
     if (isinstance(x, A) and isinstance(y, A)) or (isinstance(x, B) and isinstance(y, B)):
         # Here, types of `x` and `y` can be narrowd since all `or` arms constraint them.
@@ -155,7 +155,7 @@ def _(x: A | B | C):
         reveal_type(x)  # revealed:  B & ~C
     else:
         # ~(B & ~C) -> ~B | C -> (A & ~B) | (C & ~B) | C -> (A & ~B) | C
-        reveal_type(x)  # revealed: A & ~B | C
+        reveal_type(x)  # revealed: (A & ~B) | C
 ```
 
 ## mixing `or` and `not`
@@ -167,7 +167,7 @@ class C: ...
 
 def _(x: A | B | C):
     if isinstance(x, B) or not isinstance(x, C):
-        reveal_type(x)  # revealed: B | A & ~C
+        reveal_type(x)  # revealed: B | (A & ~C)
     else:
         reveal_type(x)  # revealed: C & ~B
 ```
@@ -181,7 +181,7 @@ class C: ...
 
 def _(x: A | B | C):
     if isinstance(x, A) or (isinstance(x, B) and not isinstance(x, C)):
-        reveal_type(x)  # revealed:  A | B & ~C
+        reveal_type(x)  # revealed:  A | (B & ~C)
     else:
         # ~(A | (B & ~C)) -> ~A & ~(B & ~C) -> ~A & (~B | C) -> (~A & C) | (~A ~ B)
         reveal_type(x)  # revealed:  C & ~A
@@ -197,7 +197,7 @@ class C: ...
 def _(x: A | B | C):
     if isinstance(x, A) and (isinstance(x, B) or not isinstance(x, C)):
         # A & (B | ~C) -> (A & B) | (A & ~C)
-        reveal_type(x)  # revealed:  A & B | A & ~C
+        reveal_type(x)  # revealed:  (A & B) | (A & ~C)
     else:
         # ~((A & B) | (A & ~C)) ->
         # ~(A & B) & ~(A & ~C) ->
@@ -206,7 +206,7 @@ def _(x: A | B | C):
         # ~A | (~A & C) | (~B & C) ->
         # ~A | (C & ~B) ->
         # ~A | (C & ~B)  The positive side of ~A is  A | B | C ->
-        reveal_type(x)  # revealed:  B & ~A | C & ~A | C & ~B
+        reveal_type(x)  # revealed:  (B & ~A) | (C & ~A) | (C & ~B)
 ```
 
 ## Boolean expression internal narrowing

crates/red_knot_python_semantic/resources/mdtest/narrow/conditionals/elif_else.md

@@ -20,11 +20,9 @@ def _(flag1: bool, flag2: bool):
     x = 1 if flag1 else 2 if flag2 else 3
 
     if x == 1:
-        # TODO should be Literal[1]
-        reveal_type(x)  # revealed: Literal[1, 2, 3]
+        reveal_type(x)  # revealed: Literal[1]
     elif x == 2:
-        # TODO should be Literal[2]
-        reveal_type(x)  # revealed: Literal[2, 3]
+        reveal_type(x)  # revealed: Literal[2]
     else:
         reveal_type(x)  # revealed: Literal[3]
 ```
@@ -38,14 +36,11 @@ def _(flag1: bool, flag2: bool):
     if x != 1:
         reveal_type(x)  # revealed: Literal[2, 3]
     elif x != 2:
-        # TODO should be `Literal[1]`
-        reveal_type(x)  # revealed: Literal[1, 3]
+        reveal_type(x)  # revealed: Literal[1]
     elif x == 3:
-        # TODO should be Never
-        reveal_type(x)  # revealed: Literal[1, 2, 3]
+        reveal_type(x)  # revealed: Never
     else:
-        # TODO should be Never
-        reveal_type(x)  # revealed: Literal[1, 2]
+        reveal_type(x)  # revealed: Never
 ```
 
 ## Assignment expressions

crates/red_knot_python_semantic/resources/mdtest/narrow/conditionals/eq.md

@@ -9,8 +9,7 @@ def _(flag: bool):
     if x != None:
         reveal_type(x)  # revealed: Literal[1]
     else:
-        # TODO should be None
-        reveal_type(x)  # revealed: None | Literal[1]
+        reveal_type(x)  # revealed: None
 ```
 
 ## `!=` for other singleton types
@@ -22,8 +21,7 @@ def _(flag: bool):
     if x != False:
         reveal_type(x)  # revealed: Literal[True]
     else:
-        # TODO should be Literal[False]
-        reveal_type(x)  # revealed: bool
+        reveal_type(x)  # revealed: Literal[False]
 ```
 
 ## `x != y` where `y` is of literal type
@@ -47,8 +45,7 @@ def _(flag: bool):
     if C != A:
         reveal_type(C)  # revealed: Literal[B]
     else:
-        # TODO should be Literal[A]
-        reveal_type(C)  # revealed: Literal[A, B]
+        reveal_type(C)  # revealed: Literal[A]
 ```
 
 ## `x != y` where `y` has multiple single-valued options
@@ -61,8 +58,7 @@ def _(flag1: bool, flag2: bool):
     if x != y:
         reveal_type(x)  # revealed: Literal[1, 2]
     else:
-        # TODO should be Literal[2]
-        reveal_type(x)  # revealed: Literal[1, 2]
+        reveal_type(x)  # revealed: Literal[2]
 ```
 
 ## `!=` for non-single-valued types
@@ -101,6 +97,61 @@ def f() -> Literal[1, 2, 3]:
 if (x := f()) != 1:
     reveal_type(x)  # revealed: Literal[2, 3]
 else:
-    # TODO should be Literal[1]
-    reveal_type(x)  # revealed: Literal[1, 2, 3]
+    reveal_type(x)  # revealed: Literal[1]
+```
+
+## Union with `Any`
+
+```py
+from typing import Any
+
+def _(x: Any | None, y: Any | None):
+    if x != 1:
+        reveal_type(x)  # revealed: (Any & ~Literal[1]) | None
+    if y == 1:
+        reveal_type(y)  # revealed: Any & ~None
+```
+
+## Booleans and integers
+
+```py
+from typing import Literal
+
+def _(b: bool, i: Literal[1, 2]):
+    if b == 1:
+        reveal_type(b)  # revealed: Literal[True]
+    else:
+        reveal_type(b)  # revealed: Literal[False]
+
+    if b == 6:
+        reveal_type(b)  # revealed: Never
+    else:
+        reveal_type(b)  # revealed: bool
+
+    if b == 0:
+        reveal_type(b)  # revealed: Literal[False]
+    else:
+        reveal_type(b)  # revealed: Literal[True]
+
+    if i == True:
+        reveal_type(i)  # revealed: Literal[1]
+    else:
+        reveal_type(i)  # revealed: Literal[2]
+```
+
+## Narrowing `LiteralString` in union
+
+```py
+from typing_extensions import Literal, LiteralString, Any
+
+def _(s: LiteralString | None, t: LiteralString | Any):
+    if s == "foo":
+        reveal_type(s)  # revealed: Literal["foo"]
+
+    if s == 1:
+        reveal_type(s)  # revealed: Never
+
+    if t == "foo":
+        # TODO could be `Literal["foo"] | Any`
+        reveal_type(t)  # revealed: LiteralString | Any
 ```

crates/red_knot_python_semantic/resources/mdtest/narrow/conditionals/nested.md

@@ -31,17 +31,14 @@ def _(flag1: bool, flag2: bool):
     if x != 1:
         reveal_type(x)  # revealed: Literal[2, 3]
         if x == 2:
-            # TODO should be `Literal[2]`
-            reveal_type(x)  # revealed: Literal[2, 3]
+            reveal_type(x)  # revealed: Literal[2]
         elif x == 3:
             reveal_type(x)  # revealed: Literal[3]
         else:
             reveal_type(x)  # revealed: Never
 
     elif x != 2:
-        # TODO should be Literal[1]
-        reveal_type(x)  # revealed: Literal[1, 3]
+        reveal_type(x)  # revealed: Literal[1]
     else:
-        # TODO should be Never
-        reveal_type(x)  # revealed: Literal[1, 2, 3]
+        reveal_type(x)  # revealed: Never
 ```

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

@@ -82,19 +82,19 @@ class B: ...
 
 def f(x: A | B):
     if x:
-        reveal_type(x)  # revealed: A & ~AlwaysFalsy | B & ~AlwaysFalsy
+        reveal_type(x)  # revealed: (A & ~AlwaysFalsy) | (B & ~AlwaysFalsy)
     else:
-        reveal_type(x)  # revealed: A & ~AlwaysTruthy | B & ~AlwaysTruthy
+        reveal_type(x)  # revealed: (A & ~AlwaysTruthy) | (B & ~AlwaysTruthy)
 
     if x and not x:
-        reveal_type(x)  # revealed: A & ~AlwaysFalsy & ~AlwaysTruthy | B & ~AlwaysFalsy & ~AlwaysTruthy
+        reveal_type(x)  # revealed: (A & ~AlwaysFalsy & ~AlwaysTruthy) | (B & ~AlwaysFalsy & ~AlwaysTruthy)
     else:
         reveal_type(x)  # revealed: A | B
 
     if x or not x:
         reveal_type(x)  # revealed: A | B
     else:
-        reveal_type(x)  # revealed: A & ~AlwaysTruthy & ~AlwaysFalsy | B & ~AlwaysTruthy & ~AlwaysFalsy
+        reveal_type(x)  # revealed: (A & ~AlwaysTruthy & ~AlwaysFalsy) | (B & ~AlwaysTruthy & ~AlwaysFalsy)
 ```
 
 ### Truthiness of Types
@@ -111,9 +111,9 @@ x = int if flag() else str
 reveal_type(x)  # revealed: Literal[int, str]
 
 if x:
-    reveal_type(x)  # revealed: Literal[int] & ~AlwaysFalsy | Literal[str] & ~AlwaysFalsy
+    reveal_type(x)  # revealed: (Literal[int] & ~AlwaysFalsy) | (Literal[str] & ~AlwaysFalsy)
 else:
-    reveal_type(x)  # revealed: Literal[int] & ~AlwaysTruthy | Literal[str] & ~AlwaysTruthy
+    reveal_type(x)  # revealed: (Literal[int] & ~AlwaysTruthy) | (Literal[str] & ~AlwaysTruthy)
 ```
 
 ## Determined Truthiness
@@ -176,12 +176,12 @@ if isinstance(x, str) and not isinstance(x, B):
 
     z = x if flag() else y
 
-    reveal_type(z)  # revealed: A & str & ~B | Literal[0, 42, "", "hello"]
+    reveal_type(z)  # revealed: (A & str & ~B) | Literal[0, 42, "", "hello"]
 
     if z:
-        reveal_type(z)  # revealed: A & str & ~B & ~AlwaysFalsy | Literal[42, "hello"]
+        reveal_type(z)  # revealed: (A & str & ~B & ~AlwaysFalsy) | Literal[42, "hello"]
     else:
-        reveal_type(z)  # revealed: A & str & ~B & ~AlwaysTruthy | Literal[0, ""]
+        reveal_type(z)  # revealed: (A & str & ~B & ~AlwaysTruthy) | Literal[0, ""]
 ```
 
 ## Narrowing Multiple Variables
@@ -264,13 +264,13 @@ def _(
 ):
     reveal_type(ta)  # revealed: type[TruthyClass] | type[AmbiguousClass]
     if ta:
-        reveal_type(ta)  # revealed: type[TruthyClass] | type[AmbiguousClass] & ~AlwaysFalsy
+        reveal_type(ta)  # revealed: type[TruthyClass] | (type[AmbiguousClass] & ~AlwaysFalsy)
 
     reveal_type(af)  # revealed: type[AmbiguousClass] | type[FalsyClass]
     if af:
         reveal_type(af)  # revealed: type[AmbiguousClass] & ~AlwaysFalsy
 
-    # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `MetaDeferred`; the return type of its bool method (`MetaAmbiguous`) isn't assignable to `bool"
+    # error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `MetaDeferred`"
     if d:
         # TODO: Should be `Unknown`
         reveal_type(d)  # revealed: type[DeferredClass] & ~AlwaysFalsy
@@ -296,12 +296,12 @@ def _(x: Literal[0, 1]):
     reveal_type(x and A())  # revealed: Literal[0] | A
 
 def _(x: str):
-    reveal_type(x or A())  # revealed: str & ~AlwaysFalsy | A
-    reveal_type(x and A())  # revealed: str & ~AlwaysTruthy | A
+    reveal_type(x or A())  # revealed: (str & ~AlwaysFalsy) | A
+    reveal_type(x and A())  # revealed: (str & ~AlwaysTruthy) | A
 
 def _(x: bool | str):
-    reveal_type(x or A())  # revealed: Literal[True] | str & ~AlwaysFalsy | A
-    reveal_type(x and A())  # revealed: Literal[False] | str & ~AlwaysTruthy | A
+    reveal_type(x or A())  # revealed: Literal[True] | (str & ~AlwaysFalsy) | A
+    reveal_type(x and A())  # revealed: Literal[False] | (str & ~AlwaysTruthy) | A
 
 class Falsy:
     def __bool__(self) -> Literal[False]:

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

@@ -127,7 +127,7 @@ class B: ...
 
 def _[T](x: A | B):
     if type(x) is A[str]:
-        reveal_type(x)  # revealed: A[int] & A[Unknown] | B & A[Unknown]
+        reveal_type(x)  # revealed: (A[int] & A[Unknown]) | (B & A[Unknown])
     else:
         reveal_type(x)  # revealed: A[int] | B
 ```

crates/red_knot_python_semantic/resources/mdtest/overloads.md

@@ -309,39 +309,52 @@ reveal_type(func(""))  # revealed: Literal[""]
 
 ### At least two overloads
 
+<!-- snapshot-diagnostics -->
+
 At least two `@overload`-decorated definitions must be present.
 
 ```py
 from typing import overload
 
-# TODO: error
 @overload
 def func(x: int) -> int: ...
+
+# error: [invalid-overload]
 def func(x: int | str) -> int | str:
     return x
 ```
 
+```pyi
+from typing import overload
+
+@overload
+# error: [invalid-overload]
+def func(x: int) -> int: ...
+```
+
 ### Overload without an implementation
 
 #### Regular modules
 
+<!-- snapshot-diagnostics -->
+
 In regular modules, a series of `@overload`-decorated definitions must be followed by exactly one
 non-`@overload`-decorated definition (for the same function/method).
 
 ```py
 from typing import overload
 
-# TODO: error because implementation does not exists
 @overload
 def func(x: int) -> int: ...
 @overload
+# error: [invalid-overload] "Overloaded non-stub function `func` must have an implementation"
 def func(x: str) -> str: ...
 
 class Foo:
-    # TODO: error because implementation does not exists
     @overload
     def method(self, x: int) -> int: ...
     @overload
+    # error: [invalid-overload] "Overloaded non-stub function `method` must have an implementation"
     def method(self, x: str) -> str: ...
 ```
 
@@ -394,12 +407,12 @@ from it.
 
 ```py
 class Foo:
-    # TODO: Error because implementation does not exists
     @overload
     @abstractmethod
     def f(self, x: int) -> int: ...
     @overload
     @abstractmethod
+    # error: [invalid-overload]
     def f(self, x: str) -> str: ...
 ```
 
@@ -411,6 +424,7 @@ class PartialFoo1(ABC):
     @abstractmethod
     def f(self, x: int) -> int: ...
     @overload
+    # error: [invalid-overload]
     def f(self, x: str) -> str: ...
 
 class PartialFoo(ABC):
@@ -418,16 +432,16 @@ class PartialFoo(ABC):
     def f(self, x: int) -> int: ...
     @overload
     @abstractmethod
+    # error: [invalid-overload]
     def f(self, x: str) -> str: ...
 ```
 
 ### Inconsistent decorators
 
-#### `@staticmethod` / `@classmethod`
+#### `@staticmethod`
 
-If one overload signature is decorated with `@staticmethod` or `@classmethod`, all overload
-signatures must be similarly decorated. The implementation, if present, must also have a consistent
-decorator.
+If one overload signature is decorated with `@staticmethod`, all overload signatures must be
+similarly decorated. The implementation, if present, must also have a consistent decorator.
 
 ```py
 from __future__ import annotations
@@ -471,39 +485,54 @@ class CheckStaticMethod:
     @staticmethod
     def method4(x: int | str) -> int | str:
         return x
+```
+
+#### `@classmethod`
+
+<!-- snapshot-diagnostics -->
+
+The same rules apply for `@classmethod` as for [`@staticmethod`](#staticmethod).
+
+```py
+from __future__ import annotations
+
+from typing import overload
 
 class CheckClassMethod:
     def __init__(self, x: int) -> None:
         self.x = x
-    # TODO: error because `@classmethod` does not exist on all overloads
+
     @overload
     @classmethod
     def try_from1(cls, x: int) -> CheckClassMethod: ...
     @overload
     def try_from1(cls, x: str) -> None: ...
     @classmethod
+    # error: [invalid-overload] "Overloaded function `try_from1` does not use the `@classmethod` decorator consistently"
     def try_from1(cls, x: int | str) -> CheckClassMethod | None:
         if isinstance(x, int):
             return cls(x)
         return None
-    # TODO: error because `@classmethod` does not exist on all overloads
+
     @overload
     def try_from2(cls, x: int) -> CheckClassMethod: ...
     @overload
     @classmethod
     def try_from2(cls, x: str) -> None: ...
     @classmethod
+    # error: [invalid-overload]
     def try_from2(cls, x: int | str) -> CheckClassMethod | None:
         if isinstance(x, int):
             return cls(x)
         return None
-    # TODO: error because `@classmethod` does not exist on the implementation
+
     @overload
     @classmethod
     def try_from3(cls, x: int) -> CheckClassMethod: ...
     @overload
     @classmethod
     def try_from3(cls, x: str) -> None: ...
+    # error: [invalid-overload]
     def try_from3(cls, x: int | str) -> CheckClassMethod | None:
         if isinstance(x, int):
             return cls(x)
@@ -522,13 +551,15 @@ class CheckClassMethod:
         return None
 ```
 
-#### `@final` / `@override`
+#### `@final`
 
-If a `@final` or `@override` decorator is supplied for a function with overloads, the decorator
-should be applied only to the overload implementation if it is present.
+<!-- snapshot-diagnostics -->
+
+If a `@final` decorator is supplied for a function with overloads, the decorator should be applied
+only to the overload implementation if it is present.
 
 ```py
-from typing_extensions import final, overload, override
+from typing_extensions import final, overload
 
 class Foo:
     @overload
@@ -538,68 +569,31 @@ class Foo:
     @final
     def method1(self, x: int | str) -> int | str:
         return x
-    # TODO: error because `@final` is not on the implementation
+
     @overload
     @final
     def method2(self, x: int) -> int: ...
     @overload
     def method2(self, x: str) -> str: ...
+    # error: [invalid-overload]
     def method2(self, x: int | str) -> int | str:
         return x
-    # TODO: error because `@final` is not on the implementation
+
     @overload
     def method3(self, x: int) -> int: ...
     @overload
     @final
     def method3(self, x: str) -> str: ...
+    # error: [invalid-overload]
     def method3(self, x: int | str) -> int | str:
         return x
-
-class Base:
-    @overload
-    def method(self, x: int) -> int: ...
-    @overload
-    def method(self, x: str) -> str: ...
-    def method(self, x: int | str) -> int | str:
-        return x
-
-class Sub1(Base):
-    @overload
-    def method(self, x: int) -> int: ...
-    @overload
-    def method(self, x: str) -> str: ...
-    @override
-    def method(self, x: int | str) -> int | str:
-        return x
-
-class Sub2(Base):
-    # TODO: error because `@override` is not on the implementation
-    @overload
-    def method(self, x: int) -> int: ...
-    @overload
-    @override
-    def method(self, x: str) -> str: ...
-    def method(self, x: int | str) -> int | str:
-        return x
-
-class Sub3(Base):
-    # TODO: error because `@override` is not on the implementation
-    @overload
-    @override
-    def method(self, x: int) -> int: ...
-    @overload
-    def method(self, x: str) -> str: ...
-    def method(self, x: int | str) -> int | str:
-        return x
 ```
 
-#### `@final` / `@override` in stub files
-
-If an overload implementation isn’t present (for example, in a stub file), the `@final` or
-`@override` decorator should be applied only to the first overload.
+If an overload implementation isn't present (for example, in a stub file), the `@final` decorator
+should be applied only to the first overload.
 
 ```pyi
-from typing_extensions import final, overload, override
+from typing_extensions import final, overload
 
 class Foo:
     @overload
@@ -608,12 +602,65 @@ class Foo:
     @overload
     def method1(self, x: str) -> str: ...
 
-    # TODO: error because `@final` is not on the first overload
     @overload
     def method2(self, x: int) -> int: ...
     @final
     @overload
+    # error: [invalid-overload]
     def method2(self, x: str) -> str: ...
+```
+
+#### `@override`
+
+<!-- snapshot-diagnostics -->
+
+The same rules apply for `@override` as for [`@final`](#final).
+
+```py
+from typing_extensions import overload, override
+
+class Base:
+    @overload
+    def method(self, x: int) -> int: ...
+    @overload
+    def method(self, x: str) -> str: ...
+    def method(self, x: int | str) -> int | str:
+        return x
+
+class Sub1(Base):
+    @overload
+    def method(self, x: int) -> int: ...
+    @overload
+    def method(self, x: str) -> str: ...
+    @override
+    def method(self, x: int | str) -> int | str:
+        return x
+
+class Sub2(Base):
+    @overload
+    def method(self, x: int) -> int: ...
+    @overload
+    @override
+    def method(self, x: str) -> str: ...
+    # error: [invalid-overload]
+    def method(self, x: int | str) -> int | str:
+        return x
+
+class Sub3(Base):
+    @overload
+    @override
+    def method(self, x: int) -> int: ...
+    @overload
+    def method(self, x: str) -> str: ...
+    # error: [invalid-overload]
+    def method(self, x: int | str) -> int | str:
+        return x
+```
+
+And, similarly, in stub files:
+
+```pyi
+from typing_extensions import overload, override
 
 class Base:
     @overload
@@ -629,10 +676,10 @@ class Sub1(Base):
     def method(self, x: str) -> str: ...
 
 class Sub2(Base):
-    # TODO: error because `@override` is not on the first overload
     @overload
     def method(self, x: int) -> int: ...
     @overload
     @override
+    # error: [invalid-overload]
     def method(self, x: str) -> str: ...
 ```

crates/red_knot_python_semantic/resources/mdtest/scopes/builtin.md

@@ -13,7 +13,7 @@ if returns_bool():
     chr: int = 1
 
 def f():
-    reveal_type(chr)  # revealed: int | (def chr(i: int | SupportsIndex, /) -> str)
+    reveal_type(chr)  # revealed: int | (def chr(i: SupportsIndex, /) -> str)
 ```
 
 ## Conditionally global or builtin, with annotation
@@ -28,5 +28,5 @@ if returns_bool():
     chr: int = 1
 
 def f():
-    reveal_type(chr)  # revealed: int | (def chr(i: int | SupportsIndex, /) -> str)
+    reveal_type(chr)  # revealed: int | (def chr(i: SupportsIndex, /) -> str)
 ```

crates/red_knot_python_semantic/resources/mdtest/scopes/eager.md

@@ -404,7 +404,7 @@ x = int
 class C:
     var: ClassVar[x]
 
-reveal_type(C.var)  # revealed: Unknown | str
+reveal_type(C.var)  # revealed: str
 
 x = str
 ```

crates/red_knot_python_semantic/resources/mdtest/scopes/global.md

@@ -0,0 +1,177 @@
+# `global` references
+
+## Implicit global in function
+
+A name reference to a never-defined symbol in a function is implicitly a global lookup.
+
+```py
+x = 1
+
+def f():
+    reveal_type(x)  # revealed: Unknown | Literal[1]
+```
+
+## Explicit global in function
+
+```py
+x = 1
+
+def f():
+    global x
+    reveal_type(x)  # revealed: Unknown | Literal[1]
+```
+
+## Unassignable type in function
+
+```py
+x: int = 1
+
+def f():
+    y: int = 1
+    # error: [invalid-assignment] "Object of type `Literal[""]` is not assignable to `int`"
+    y = ""
+
+    global x
+    # TODO: error: [invalid-assignment] "Object of type `Literal[""]` is not assignable to `int`"
+    x = ""
+```
+
+## Nested intervening scope
+
+A `global` statement causes lookup to skip any bindings in intervening scopes:
+
+```py
+x: int = 1
+
+def outer():
+    x: str = ""
+
+    def inner():
+        global x
+        # TODO: revealed: int
+        reveal_type(x)  # revealed: str
+```
+
+## Narrowing
+
+An assignment following a `global` statement should narrow the type in the local scope after the
+assignment.
+
+```py
+x: int | None
+
+def f():
+    global x
+    x = 1
+    reveal_type(x)  # revealed: Literal[1]
+```
+
+## `nonlocal` and `global`
+
+A binding cannot be both `nonlocal` and `global`. This should emit a semantic syntax error. CPython
+marks the `nonlocal` line, while `mypy`, `pyright`, and `ruff` (`PLE0115`) mark the `global` line.
+
+```py
+x = 1
+
+def f():
+    x = 1
+    def g() -> None:
+        nonlocal x
+        global x  # TODO: error: [invalid-syntax] "name 'x' is nonlocal and global"
+        x = None
+```
+
+## Global declaration after `global` statement
+
+```py
+def f():
+    global x
+    # TODO this should also not be an error
+    y = x  # error: [unresolved-reference] "Name `x` used when not defined"
+    x = 1  # No error.
+
+x = 2
+```
+
+## Semantic syntax errors
+
+Using a name prior to its `global` declaration in the same scope is a syntax error.
+
+```py
+x = 1
+
+def f():
+    print(x)  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x
+    print(x)
+
+def f():
+    global x
+    print(x)  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x
+    print(x)
+
+def f():
+    print(x)  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x, y
+    print(x)
+
+def f():
+    global x, y
+    print(x)  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x, y
+    print(x)
+
+def f():
+    x = 1  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x
+    x = 1
+
+def f():
+    global x
+    x = 1  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x
+    x = 1
+
+def f():
+    del x  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x, y
+    del x
+
+def f():
+    global x, y
+    del x  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x, y
+    del x
+
+def f():
+    del x  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x
+    del x
+
+def f():
+    global x
+    del x  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x
+    del x
+
+def f():
+    del x  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x, y
+    del x
+
+def f():
+    global x, y
+    del x  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x, y
+    del x
+
+def f():
+    print(f"{x=}")  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+    global x
+
+# still an error in module scope
+x = None  # TODO: error: [invalid-syntax] name `x` is used prior to global declaration
+global x
+```

crates/red_knot_python_semantic/resources/mdtest/scopes/nonlocal.md

@@ -43,14 +43,3 @@ def f():
         def h():
             reveal_type(x)  # revealed: Unknown | Literal[1]
 ```
-
-## Implicit global in function
-
-A name reference to a never-defined symbol in a function is implicitly a global lookup.
-
-```py
-x = 1
-
-def f():
-    reveal_type(x)  # revealed: Unknown | Literal[1]
-```

crates/red_knot_python_semantic/resources/mdtest/shadowing/class.md

@@ -5,7 +5,7 @@
 ```py
 class C: ...
 
-C = 1  # error: "Implicit shadowing of class `C`; annotate to make it explicit if this is intentional"
+C = 1  # error: "Implicit shadowing of class `C`"
 ```
 
 ## Explicit

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

@@ -15,7 +15,7 @@ def f(x: str):
 ```py
 def f(): ...
 
-f = 1  # error: "Implicit shadowing of function `f`; annotate to make it explicit if this is intentional"
+f = 1  # error: "Implicit shadowing of function `f`"
 ```
 
 ## Explicit shadowing

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

@@ -28,12 +28,12 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attrib
 # Diagnostics
 
 ```
-error: lint:invalid-assignment
-  --> /src/mdtest_snippet.py:11:1
+error: lint:invalid-assignment: Invalid assignment to data descriptor attribute `attr` on type `C` with custom `__set__` method
+  --> src/mdtest_snippet.py:11:1
    |
 10 | # TODO: ideally, we would mention why this is an invalid assignment (wrong number of arguments for `__set__`)
 11 | instance.attr = 1  # error: [invalid-assignment]
-   | ^^^^^^^^^^^^^ Invalid assignment to data descriptor attribute `attr` on type `C` with custom `__set__` method
+   | ^^^^^^^^^^^^^
    |
 
 ```

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

@@ -29,12 +29,12 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attrib
 # Diagnostics
 
 ```
-error: lint:invalid-assignment
-  --> /src/mdtest_snippet.py:12:1
+error: lint:invalid-assignment: Invalid assignment to data descriptor attribute `attr` on type `C` with custom `__set__` method
+  --> src/mdtest_snippet.py:12:1
    |
 11 | # TODO: ideally, we would mention why this is an invalid assignment (wrong argument type for `value` parameter)
 12 | instance.attr = "wrong"  # error: [invalid-assignment]
-   | ^^^^^^^^^^^^^ Invalid assignment to data descriptor attribute `attr` on type `C` with custom `__set__` method
+   | ^^^^^^^^^^^^^
    |
 
 ```

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

@@ -26,13 +26,13 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attrib
 # Diagnostics
 
 ```
-error: lint:invalid-assignment
- --> /src/mdtest_snippet.py:6:1
+error: lint:invalid-assignment: Object of type `Literal["wrong"]` is not assignable to attribute `attr` of type `int`
+ --> src/mdtest_snippet.py:6:1
   |
 4 | instance = C()
 5 | instance.attr = 1  # fine
 6 | instance.attr = "wrong"  # error: [invalid-assignment]
-  | ^^^^^^^^^^^^^ Object of type `Literal["wrong"]` is not assignable to attribute `attr` of type `int`
+  | ^^^^^^^^^^^^^
 7 |
 8 | C.attr = 1  # fine
   |
@@ -40,12 +40,12 @@ error: lint:invalid-assignment
 ```
 
 ```
-error: lint:invalid-assignment
- --> /src/mdtest_snippet.py:9:1
+error: lint:invalid-assignment: Object of type `Literal["wrong"]` is not assignable to attribute `attr` of type `int`
+ --> src/mdtest_snippet.py:9:1
   |
 8 | C.attr = 1  # fine
 9 | C.attr = "wrong"  # error: [invalid-assignment]
-  | ^^^^^^ Object of type `Literal["wrong"]` is not assignable to attribute `attr` of type `int`
+  | ^^^^^^
   |
 
 ```

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

@@ -26,13 +26,13 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attrib
 # Diagnostics
 
 ```
-warning: lint:possibly-unbound-attribute
- --> /src/mdtest_snippet.py:6:5
+warning: lint:possibly-unbound-attribute: Attribute `attr` on type `Literal[C]` is possibly unbound
+ --> src/mdtest_snippet.py:6:5
   |
 4 |             attr: int = 0
 5 |
 6 |     C.attr = 1  # error: [possibly-unbound-attribute]
-  |     ^^^^^^ Attribute `attr` on type `Literal[C]` is possibly unbound
+  |     ^^^^^^
 7 |
 8 |     instance = C()
   |
@@ -40,12 +40,12 @@ warning: lint:possibly-unbound-attribute
 ```
 
 ```
-warning: lint:possibly-unbound-attribute
- --> /src/mdtest_snippet.py:9:5
+warning: lint:possibly-unbound-attribute: Attribute `attr` on type `C` is possibly unbound
+ --> src/mdtest_snippet.py:9:5
   |
 8 |     instance = C()
 9 |     instance.attr = 1  # error: [possibly-unbound-attribute]
-  |     ^^^^^^^^^^^^^ Attribute `attr` on type `C` is possibly unbound
+  |     ^^^^^^^^^^^^^
   |
 
 ```

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

@@ -26,13 +26,13 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attrib
 # Diagnostics
 
 ```
-error: lint:invalid-assignment
- --> /src/mdtest_snippet.py:7:1
+error: lint:invalid-assignment: Object of type `Literal["wrong"]` is not assignable to attribute `attr` of type `int`
+ --> src/mdtest_snippet.py:7:1
   |
 5 | instance = C()
 6 | instance.attr = 1  # fine
 7 | instance.attr = "wrong"  # error: [invalid-assignment]
-  | ^^^^^^^^^^^^^ Object of type `Literal["wrong"]` is not assignable to attribute `attr` of type `int`
+  | ^^^^^^^^^^^^^
 8 |
 9 | C.attr = 1  # error: [invalid-attribute-access]
   |
@@ -40,13 +40,13 @@ error: lint:invalid-assignment
 ```
 
 ```
-error: lint:invalid-attribute-access
- --> /src/mdtest_snippet.py:9:1
+error: lint:invalid-attribute-access: Cannot assign to instance attribute `attr` from the class object `Literal[C]`
+ --> src/mdtest_snippet.py:9:1
   |
 7 | instance.attr = "wrong"  # error: [invalid-assignment]
 8 |
 9 | C.attr = 1  # error: [invalid-attribute-access]
-  | ^^^^^^ Cannot assign to instance attribute `attr` from the class object `Literal[C]`
+  | ^^^^^^
   |
 
 ```

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

@@ -37,12 +37,12 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attrib
 # Diagnostics
 
 ```
-error: lint:invalid-assignment
-  --> /src/mdtest_snippet.py:11:5
+error: lint:invalid-assignment: Object of type `Literal[1]` is not assignable to attribute `attr` on type `Literal[C1, C1]`
+  --> src/mdtest_snippet.py:11:5
    |
 10 |     # TODO: The error message here could be improved to explain why the assignment fails.
 11 |     C1.attr = 1  # error: [invalid-assignment]
-   |     ^^^^^^^ Object of type `Literal[1]` is not assignable to attribute `attr` on type `Literal[C1, C1]`
+   |     ^^^^^^^
 12 |
 13 |     class C2:
    |

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

@@ -23,13 +23,13 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attrib
 # Diagnostics
 
 ```
-error: lint:unresolved-attribute
- --> /src/mdtest_snippet.py:3:1
+error: lint:unresolved-attribute: Unresolved attribute `non_existent` on type `Literal[C]`.
+ --> src/mdtest_snippet.py:3:1
   |
 1 | class C: ...
 2 |
 3 | C.non_existent = 1  # error: [unresolved-attribute]
-  | ^^^^^^^^^^^^^^ Unresolved attribute `non_existent` on type `Literal[C]`.
+  | ^^^^^^^^^^^^^^
 4 |
 5 | instance = C()
   |
@@ -37,12 +37,12 @@ error: lint:unresolved-attribute
 ```
 
 ```
-error: lint:unresolved-attribute
- --> /src/mdtest_snippet.py:6:1
+error: lint:unresolved-attribute: Unresolved attribute `non_existent` on type `C`.
+ --> src/mdtest_snippet.py:6:1
   |
 5 | instance = C()
 6 | instance.non_existent = 1  # error: [unresolved-attribute]
-  | ^^^^^^^^^^^^^^^^^^^^^ Unresolved attribute `non_existent` on type `C`.
+  | ^^^^^^^^^^^^^^^^^^^^^
   |
 
 ```

crates/red_knot_python_semantic/resources/mdtest/snapshots/attribute_assignment.md_-_Attribute_assignment_-_`ClassVar`s.snap

@@ -27,12 +27,12 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/attrib
 # Diagnostics
 
 ```
-error: lint:invalid-assignment
- --> /src/mdtest_snippet.py:7:1
+error: lint:invalid-assignment: Object of type `Literal["wrong"]` is not assignable to attribute `attr` of type `int`
+ --> src/mdtest_snippet.py:7:1
   |
 6 | C.attr = 1  # fine
 7 | C.attr = "wrong"  # error: [invalid-assignment]
-  | ^^^^^^ Object of type `Literal["wrong"]` is not assignable to attribute `attr` of type `int`
+  | ^^^^^^
 8 |
 9 | instance = C()
   |
@@ -40,12 +40,12 @@ error: lint:invalid-assignment
 ```
 
 ```
-error: lint:invalid-attribute-access
-  --> /src/mdtest_snippet.py:10:1
+error: lint:invalid-attribute-access: Cannot assign to ClassVar `attr` from an instance of type `C`
+  --> src/mdtest_snippet.py:10:1
    |
  9 | instance = C()
 10 | instance.attr = 1  # error: [invalid-attribute-access]
-   | ^^^^^^^^^^^^^ Cannot assign to ClassVar `attr` from an instance of type `C`
+   | ^^^^^^^^^^^^^
    |
 
 ```

crates/red_knot_python_semantic/resources/mdtest/snapshots/basic.md_-_Structures_-_Unresolvable_module_import.snap

@@ -18,11 +18,11 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/import/basic.md
 # Diagnostics
 
 ```
-error: lint:unresolved-import
- --> /src/mdtest_snippet.py:1:8
+error: lint:unresolved-import: Cannot resolve import `zqzqzqzqzqzqzq`
+ --> src/mdtest_snippet.py:1:8
   |
 1 | import zqzqzqzqzqzqzq  # error: [unresolved-import] "Cannot resolve import `zqzqzqzqzqzqzq`"
-  |        ^^^^^^^^^^^^^^ Cannot resolve import `zqzqzqzqzqzqzq`
+  |        ^^^^^^^^^^^^^^
   |
 
 ```

crates/red_knot_python_semantic/resources/mdtest/snapshots/basic.md_-_Structures_-_Unresolvable_submodule_imports.snap

@@ -27,12 +27,12 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/import/basic.md
 # Diagnostics
 
 ```
-error: lint:unresolved-import
- --> /src/mdtest_snippet.py:2:8
+error: lint:unresolved-import: Cannot resolve import `a.foo`
+ --> src/mdtest_snippet.py:2:8
   |
 1 | # Topmost component resolvable, submodule not resolvable:
 2 | import a.foo  # error: [unresolved-import] "Cannot resolve import `a.foo`"
-  |        ^^^^^ Cannot resolve import `a.foo`
+  |        ^^^^^
 3 |
 4 | # Topmost component unresolvable:
   |
@@ -40,12 +40,12 @@ error: lint:unresolved-import
 ```
 
 ```
-error: lint:unresolved-import
- --> /src/mdtest_snippet.py:5:8
+error: lint:unresolved-import: Cannot resolve import `b.foo`
+ --> src/mdtest_snippet.py:5:8
   |
 4 | # Topmost component unresolvable:
 5 | import b.foo  # error: [unresolved-import] "Cannot resolve import `b.foo`"
-  |        ^^^^^ Cannot resolve import `b.foo`
+  |        ^^^^^
   |
 
 ```

crates/red_knot_python_semantic/resources/mdtest/snapshots/for.md_-_For_loops_-_Bad_`__getitem__`_method.snap

@@ -28,20 +28,22 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/loops/for.md
 # Diagnostics
 
 ```
-error: lint:not-iterable
-  --> /src/mdtest_snippet.py:10:10
+error: lint:not-iterable: Object of type `Iterable` is not iterable
+  --> src/mdtest_snippet.py:10:10
    |
  9 | # error: [not-iterable]
 10 | for x in Iterable():
-   |          ^^^^^^^^^^ Object of type `Iterable` is not iterable because it has no `__iter__` method and its `__getitem__` method has an incorrect signature for the old-style iteration protocol (expected a signature at least as permissive as `def __getitem__(self, key: int): ...`)
+   |          ^^^^^^^^^^
 11 |     reveal_type(x)  # revealed: int
    |
+info: It has no `__iter__` method and its `__getitem__` method has an incorrect signature for the old-style iteration protocol
+info: `__getitem__` must be at least as permissive as `def __getitem__(self, key: int): ...` to satisfy the old-style iteration protocol
 
 ```
 
 ```
 info: revealed-type: Revealed type
-  --> /src/mdtest_snippet.py:11:5
+  --> src/mdtest_snippet.py:11:5
    |
  9 | # error: [not-iterable]
 10 | for x in Iterable():

crates/red_knot_python_semantic/resources/mdtest/snapshots/for.md_-_For_loops_-_Invalid_iterable.snap

@@ -20,13 +20,14 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/loops/for.md
 # Diagnostics
 
 ```
-error: lint:not-iterable
- --> /src/mdtest_snippet.py:2:10
+error: lint:not-iterable: Object of type `Literal[123]` is not iterable
+ --> src/mdtest_snippet.py:2:10
   |
 1 | nonsense = 123
 2 | for x in nonsense:  # error: [not-iterable]
-  |          ^^^^^^^^ Object of type `Literal[123]` is not iterable because it doesn't have an `__iter__` method or a `__getitem__` method
+  |          ^^^^^^^^
 3 |     pass
   |
+info: It doesn't have an `__iter__` method or a `__getitem__` method
 
 ```

crates/red_knot_python_semantic/resources/mdtest/snapshots/for.md_-_For_loops_-_New_over_old_style_iteration_protocol.snap

@@ -24,14 +24,15 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/loops/for.md
 # Diagnostics
 
 ```
-error: lint:not-iterable
- --> /src/mdtest_snippet.py:6:10
+error: lint:not-iterable: Object of type `NotIterable` is not iterable
+ --> src/mdtest_snippet.py:6:10
   |
 4 |     __iter__: None = None
 5 |
 6 | for x in NotIterable():  # error: [not-iterable]
-  |          ^^^^^^^^^^^^^ Object of type `NotIterable` is not iterable because its `__iter__` attribute has type `None`, which is not callable
+  |          ^^^^^^^^^^^^^
 7 |     pass
   |
+info: Its `__iter__` attribute has type `None`, which is not callable
 
 ```

crates/red_knot_python_semantic/resources/mdtest/snapshots/for.md_-_For_loops_-_No_`__iter__`_method_and_`__getitem__`_is_not_callable.snap

@@ -25,20 +25,21 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/loops/for.md
 # Diagnostics
 
 ```
-error: lint:not-iterable
- --> /src/mdtest_snippet.py:7:10
+error: lint:not-iterable: Object of type `Bad` is not iterable
+ --> src/mdtest_snippet.py:7:10
   |
 6 | # error: [not-iterable]
 7 | for x in Bad():
-  |          ^^^^^ Object of type `Bad` is not iterable because it has no `__iter__` method and its `__getitem__` attribute has type `None`, which is not callable
+  |          ^^^^^
 8 |     reveal_type(x)  # revealed: Unknown
   |
+info: It has no `__iter__` method and its `__getitem__` attribute has type `None`, which is not callable
 
 ```
 
 ```
 info: revealed-type: Revealed type
- --> /src/mdtest_snippet.py:8:5
+ --> src/mdtest_snippet.py:8:5
   |
 6 | # error: [not-iterable]
 7 | for x in Bad():

crates/red_knot_python_semantic/resources/mdtest/snapshots/for.md_-_For_loops_-_Possibly-not-callable_`__getitem__`_method.snap

@@ -46,21 +46,23 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/loops/for.md
 # Diagnostics
 
 ```
-error: lint:not-iterable
-  --> /src/mdtest_snippet.py:22:14
+error: lint:not-iterable: Object of type `Iterable1` may not be iterable
+  --> src/mdtest_snippet.py:22:14
    |
 21 |     # error: [not-iterable]
 22 |     for x in Iterable1():
-   |              ^^^^^^^^^^^ Object of type `Iterable1` may not be iterable because it has no `__iter__` method and its `__getitem__` attribute (with type `CustomCallable`) may not be callable
+   |              ^^^^^^^^^^^
 23 |         # TODO... `int` might be ideal here?
 24 |         reveal_type(x)  # revealed: int | Unknown
    |
+info: It has no `__iter__` method and its `__getitem__` attribute is invalid
+info: `__getitem__` has type `CustomCallable`, which is not callable
 
 ```
 
 ```
 info: revealed-type: Revealed type
-  --> /src/mdtest_snippet.py:24:9
+  --> src/mdtest_snippet.py:24:9
    |
 22 |     for x in Iterable1():
 23 |         # TODO... `int` might be ideal here?
@@ -73,21 +75,23 @@ info: revealed-type: Revealed type
 ```
 
 ```
-error: lint:not-iterable
-  --> /src/mdtest_snippet.py:27:14
+error: lint:not-iterable: Object of type `Iterable2` may not be iterable
+  --> src/mdtest_snippet.py:27:14
    |
 26 |     # error: [not-iterable]
 27 |     for y in Iterable2():
-   |              ^^^^^^^^^^^ Object of type `Iterable2` may not be iterable because it has no `__iter__` method and its `__getitem__` attribute (with type `(bound method Iterable2.__getitem__(key: int) -> int) | None`) may not be callable
+   |              ^^^^^^^^^^^
 28 |         # TODO... `int` might be ideal here?
 29 |         reveal_type(y)  # revealed: int | Unknown
    |
+info: It has no `__iter__` method and its `__getitem__` attribute is invalid
+info: `__getitem__` has type `(bound method Iterable2.__getitem__(key: int) -> int) | None`, which is not callable
 
 ```
 
 ```
 info: revealed-type: Revealed type
-  --> /src/mdtest_snippet.py:29:9
+  --> src/mdtest_snippet.py:29:9
    |
 27 |     for y in Iterable2():
 28 |         # TODO... `int` might be ideal here?

crates/red_knot_python_semantic/resources/mdtest/snapshots/for.md_-_For_loops_-_Possibly_invalid_`__getitem__`_methods.snap

@@ -43,21 +43,23 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/loops/for.md
 # Diagnostics
 
 ```
-error: lint:not-iterable
-  --> /src/mdtest_snippet.py:20:14
+error: lint:not-iterable: Object of type `Iterable1` may not be iterable
+  --> src/mdtest_snippet.py:20:14
    |
 19 |     # error: [not-iterable]
 20 |     for x in Iterable1():
-   |              ^^^^^^^^^^^ Object of type `Iterable1` may not be iterable because it has no `__iter__` method and its `__getitem__` attribute (with type `(bound method Iterable1.__getitem__(item: int) -> str) | None`) may not be callable
+   |              ^^^^^^^^^^^
 21 |         # TODO: `str` might be better
 22 |         reveal_type(x)  # revealed: str | Unknown
    |
+info: It has no `__iter__` method and its `__getitem__` attribute is invalid
+info: `__getitem__` has type `(bound method Iterable1.__getitem__(item: int) -> str) | None`, which is not callable
 
 ```
 
 ```
 info: revealed-type: Revealed type
-  --> /src/mdtest_snippet.py:22:9
+  --> src/mdtest_snippet.py:22:9
    |
 20 |     for x in Iterable1():
 21 |         # TODO: `str` might be better
@@ -70,20 +72,22 @@ info: revealed-type: Revealed type
 ```
 
 ```
-error: lint:not-iterable
-  --> /src/mdtest_snippet.py:25:14
+error: lint:not-iterable: Object of type `Iterable2` may not be iterable
+  --> src/mdtest_snippet.py:25:14
    |
 24 |     # error: [not-iterable]
 25 |     for y in Iterable2():
-   |              ^^^^^^^^^^^ Object of type `Iterable2` may not be iterable because it has no `__iter__` method and its `__getitem__` method (with type `(bound method Iterable2.__getitem__(item: int) -> str) | (bound method Iterable2.__getitem__(item: str) -> int)`) may have an incorrect signature for the old-style iteration protocol (expected a signature at least as permissive as `def __getitem__(self, key: int): ...`)
+   |              ^^^^^^^^^^^
 26 |         reveal_type(y)  # revealed: str | int
    |
+info: It has no `__iter__` method and its `__getitem__` method (with type `(bound method Iterable2.__getitem__(item: int) -> str) | (bound method Iterable2.__getitem__(item: str) -> int)`) may have an incorrect signature for the old-style iteration protocol
+info: `__getitem__` must be at least as permissive as `def __getitem__(self, key: int): ...` to satisfy the old-style iteration protocol
 
 ```
 
 ```
 info: revealed-type: Revealed type
-  --> /src/mdtest_snippet.py:26:9
+  --> src/mdtest_snippet.py:26:9
    |
 24 |     # error: [not-iterable]
 25 |     for y in Iterable2():

crates/red_knot_python_semantic/resources/mdtest/snapshots/for.md_-_For_loops_-_Possibly_invalid_`__iter__`_methods.snap

@@ -47,20 +47,23 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/loops/for.md
 # Diagnostics
 
 ```
-error: lint:not-iterable
-  --> /src/mdtest_snippet.py:17:14
+error: lint:not-iterable: Object of type `Iterable1` may not be iterable
+  --> src/mdtest_snippet.py:17:14
    |
 16 |     # error: [not-iterable]
 17 |     for x in Iterable1():
-   |              ^^^^^^^^^^^ Object of type `Iterable1` may not be iterable because its `__iter__` method (with type `(bound method Iterable1.__iter__() -> Iterator) | (bound method Iterable1.__iter__(invalid_extra_arg) -> Iterator)`) may have an invalid signature (expected `def __iter__(self): ...`)
+   |              ^^^^^^^^^^^
 18 |         reveal_type(x)  # revealed: int
    |
+info: Its `__iter__` method may have an invalid signature
+info: Type of `__iter__` is `(bound method Iterable1.__iter__() -> Iterator) | (bound method Iterable1.__iter__(invalid_extra_arg) -> Iterator)`
+info: Expected signature for `__iter__` is `def __iter__(self): ...`
 
 ```
 
 ```
 info: revealed-type: Revealed type
-  --> /src/mdtest_snippet.py:18:9
+  --> src/mdtest_snippet.py:18:9
    |
 16 |     # error: [not-iterable]
 17 |     for x in Iterable1():
@@ -73,21 +76,22 @@ info: revealed-type: Revealed type
 ```
 
 ```
-error: lint:not-iterable
-  --> /src/mdtest_snippet.py:28:14
+error: lint:not-iterable: Object of type `Iterable2` may not be iterable
+  --> src/mdtest_snippet.py:28:14
    |
 27 |     # error: [not-iterable]
 28 |     for x in Iterable2():
-   |              ^^^^^^^^^^^ Object of type `Iterable2` may not be iterable because its `__iter__` attribute (with type `(bound method Iterable2.__iter__() -> Iterator) | None`) may not be callable
+   |              ^^^^^^^^^^^
 29 |         # TODO: `int` would probably be better here:
 30 |         reveal_type(x)  # revealed: int | Unknown
    |
+info: Its `__iter__` attribute (with type `(bound method Iterable2.__iter__() -> Iterator) | None`) may not be callable
 
 ```
 
 ```
 info: revealed-type: Revealed type
-  --> /src/mdtest_snippet.py:30:9
+  --> src/mdtest_snippet.py:30:9
    |
 28 |     for x in Iterable2():
 29 |         # TODO: `int` would probably be better here:

crates/red_knot_python_semantic/resources/mdtest/snapshots/for.md_-_For_loops_-_Possibly_invalid_`__next__`_method.snap

@@ -51,20 +51,22 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/loops/for.md
 # Diagnostics
 
 ```
-error: lint:not-iterable
-  --> /src/mdtest_snippet.py:28:14
+error: lint:not-iterable: Object of type `Iterable1` may not be iterable
+  --> src/mdtest_snippet.py:28:14
    |
 27 |     # error: [not-iterable]
 28 |     for x in Iterable1():
-   |              ^^^^^^^^^^^ Object of type `Iterable1` may not be iterable because its `__iter__` method returns an object of type `Iterator1`, which may have an invalid `__next__` method (expected `def __next__(self): ...`)
+   |              ^^^^^^^^^^^
 29 |         reveal_type(x)  # revealed: int | str
    |
+info: Its `__iter__` method returns an object of type `Iterator1`, which may have an invalid `__next__` method
+info: Expected signature for `__next__` is `def __next__(self): ...`)
 
 ```
 
 ```
 info: revealed-type: Revealed type
-  --> /src/mdtest_snippet.py:29:9
+  --> src/mdtest_snippet.py:29:9
    |
 27 |     # error: [not-iterable]
 28 |     for x in Iterable1():
@@ -77,21 +79,22 @@ info: revealed-type: Revealed type
 ```
 
 ```
-error: lint:not-iterable
-  --> /src/mdtest_snippet.py:32:14
+error: lint:not-iterable: Object of type `Iterable2` may not be iterable
+  --> src/mdtest_snippet.py:32:14
    |
 31 |     # error: [not-iterable]
 32 |     for y in Iterable2():
-   |              ^^^^^^^^^^^ Object of type `Iterable2` may not be iterable because its `__iter__` method returns an object of type `Iterator2`, which has a `__next__` attribute that may not be callable
+   |              ^^^^^^^^^^^
 33 |         # TODO: `int` would probably be better here:
 34 |         reveal_type(y)  # revealed: int | Unknown
    |
+info: Its `__iter__` method returns an object of type `Iterator2`, which has a `__next__` attribute that may not be callable
 
 ```
 
 ```
 info: revealed-type: Revealed type
-  --> /src/mdtest_snippet.py:34:9
+  --> src/mdtest_snippet.py:34:9
    |
 32 |     for y in Iterable2():
 33 |         # TODO: `int` would probably be better here:

crates/red_knot_python_semantic/resources/mdtest/snapshots/for.md_-_For_loops_-_Possibly_unbound_`__iter__`_and_bad_`__getitem__`_method.snap

@@ -36,20 +36,22 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/loops/for.md
 # Diagnostics
 
 ```
-error: lint:not-iterable
-  --> /src/mdtest_snippet.py:18:14
+error: lint:not-iterable: Object of type `Iterable` may not be iterable
+  --> src/mdtest_snippet.py:18:14
    |
 17 |     # error: [not-iterable]
 18 |     for x in Iterable():
-   |              ^^^^^^^^^^ Object of type `Iterable` may not be iterable because it may not have an `__iter__` method and its `__getitem__` method has an incorrect signature for the old-style iteration protocol (expected a signature at least as permissive as `def __getitem__(self, key: int): ...`)
+   |              ^^^^^^^^^^
 19 |         reveal_type(x)  # revealed: int | bytes
    |
+info: It may not have an `__iter__` method and its `__getitem__` method has an incorrect signature for the old-style iteration protocol
+info: `__getitem__` must be at least as permissive as `def __getitem__(self, key: int): ...` to satisfy the old-style iteration protocol
 
 ```
 
 ```
 info: revealed-type: Revealed type
-  --> /src/mdtest_snippet.py:19:9
+  --> src/mdtest_snippet.py:19:9
    |
 17 |     # error: [not-iterable]
 18 |     for x in Iterable():