[ty] Always infer the submodule literal for submodule attribute-access, even when we emit a diagnostic

This patch updates our protocol assignability checks to substitute for
any occurrences of `typing.Self` in method signatures, replacing it with
the class being checked for assignability against the protocol.

This requires a new helper method on signatures, `apply_self`, which
substitutes occurrences of `typing.Self` _without_ binding the `self`
parameter.

We also update the `try_upcast_to_callable` method. Before, it would
return a `Type`, since certain types upcast to a _union_ of callables,
not to a single callable. However, even in that case, we know that every
element of the union is a callable. We now return a vector of
`CallableType`. (Actually a smallvec to handle the most common case of a
single callable; and wrapped in a new type so that we can provide helper
methods.) If there is more than one element in the result, it represents
a union of callables. This lets callers get at the `CallableType`
instances in a more type-safe way. (This makes it easier for our
protocol checking code to call the new `apply_self` helper.) We also
provide an `into_type` method so that callers that really do want a
`Type` can get the original result easily.

---------

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

.github/workflows/ci.yaml

@@ -261,15 +261,15 @@ jobs:
       - name: "Install mold"
         uses: rui314/setup-mold@725a8794d15fc7563f59595bd9556495c0564878 # v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@537c30d2b45cc3aa3fb35e2bbcfb61ef93fd6f02 # v2.62.52
+        uses: taiki-e/install-action@f79fe7514db78f0a7bdba3cb6dd9c1baa7d046d9 # v2.62.56
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
-        uses: taiki-e/install-action@537c30d2b45cc3aa3fb35e2bbcfb61ef93fd6f02 # v2.62.52
+        uses: taiki-e/install-action@f79fe7514db78f0a7bdba3cb6dd9c1baa7d046d9 # v2.62.56
         with:
           tool: cargo-insta
       - name: "Install uv"
-        uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+        uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
         with:
           enable-cache: "true"
       - name: ty mdtests (GitHub annotations)
@@ -319,11 +319,11 @@ jobs:
       - name: "Install mold"
         uses: rui314/setup-mold@725a8794d15fc7563f59595bd9556495c0564878 # v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@537c30d2b45cc3aa3fb35e2bbcfb61ef93fd6f02 # v2.62.52
+        uses: taiki-e/install-action@f79fe7514db78f0a7bdba3cb6dd9c1baa7d046d9 # v2.62.56
         with:
           tool: cargo-nextest
       - name: "Install uv"
-        uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+        uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
         with:
           enable-cache: "true"
       - name: "Run tests"
@@ -352,11 +352,11 @@ jobs:
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@537c30d2b45cc3aa3fb35e2bbcfb61ef93fd6f02 # v2.62.52
+        uses: taiki-e/install-action@f79fe7514db78f0a7bdba3cb6dd9c1baa7d046d9 # v2.62.56
         with:
           tool: cargo-nextest
       - name: "Install uv"
-        uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+        uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
         with:
           enable-cache: "true"
       - name: "Run tests"
@@ -462,7 +462,7 @@ jobs:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
         with:
           persist-credentials: false
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
       - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
         with:
           shared-key: ruff-linux-debug
@@ -497,7 +497,7 @@ jobs:
       - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
         with:
           save-if: ${{ github.ref == 'refs/heads/main' }}
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
       - name: "Install Rust toolchain"
         run: rustup component add rustfmt
       # Run all code generation scripts, and verify that the current output is
@@ -532,7 +532,7 @@ jobs:
           ref: ${{ github.event.pull_request.base.ref }}
           persist-credentials: false
 
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
         with:
           python-version: ${{ env.PYTHON_VERSION }}
           activate-environment: true
@@ -638,7 +638,7 @@ jobs:
         with:
           fetch-depth: 0
           persist-credentials: false
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
       - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
         with:
           save-if: ${{ github.ref == 'refs/heads/main' }}
@@ -697,7 +697,7 @@ jobs:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
         with:
           persist-credentials: false
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
       - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
         with:
           save-if: ${{ github.ref == 'refs/heads/main' }}
@@ -748,7 +748,7 @@ jobs:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
         with:
           persist-credentials: false
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
       - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
         with:
           save-if: ${{ github.ref == 'refs/heads/main' }}
@@ -792,7 +792,7 @@ jobs:
       - name: "Install Rust toolchain"
         run: rustup show
       - name: Install uv
-        uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+        uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
         with:
           python-version: 3.13
           activate-environment: true
@@ -947,13 +947,13 @@ jobs:
       - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
         with:
           save-if: ${{ github.ref == 'refs/heads/main' }}
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
 
       - name: "Install Rust toolchain"
         run: rustup show
 
       - name: "Install codspeed"
-        uses: taiki-e/install-action@537c30d2b45cc3aa3fb35e2bbcfb61ef93fd6f02 # v2.62.52
+        uses: taiki-e/install-action@f79fe7514db78f0a7bdba3cb6dd9c1baa7d046d9 # v2.62.56
         with:
           tool: cargo-codspeed
 
@@ -987,13 +987,13 @@ jobs:
       - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
         with:
           save-if: ${{ github.ref == 'refs/heads/main' }}
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
 
       - name: "Install Rust toolchain"
         run: rustup show
 
       - name: "Install codspeed"
-        uses: taiki-e/install-action@537c30d2b45cc3aa3fb35e2bbcfb61ef93fd6f02 # v2.62.52
+        uses: taiki-e/install-action@f79fe7514db78f0a7bdba3cb6dd9c1baa7d046d9 # v2.62.56
         with:
           tool: cargo-codspeed
 
@@ -1027,13 +1027,13 @@ jobs:
       - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
         with:
           save-if: ${{ github.ref == 'refs/heads/main' }}
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
 
       - name: "Install Rust toolchain"
         run: rustup show
 
       - name: "Install codspeed"
-        uses: taiki-e/install-action@537c30d2b45cc3aa3fb35e2bbcfb61ef93fd6f02 # v2.62.52
+        uses: taiki-e/install-action@f79fe7514db78f0a7bdba3cb6dd9c1baa7d046d9 # v2.62.56
         with:
           tool: cargo-codspeed
 

.github/workflows/daily_fuzz.yaml

@@ -34,7 +34,7 @@ jobs:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
         with:
           persist-credentials: false
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"

.github/workflows/mypy_primer.yaml

@@ -43,7 +43,7 @@ jobs:
           persist-credentials: false
 
       - name: Install the latest version of uv
-        uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+        uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
 
       - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
         with:
@@ -81,7 +81,7 @@ jobs:
           persist-credentials: false
 
       - name: Install the latest version of uv
-        uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+        uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
 
       - uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
         with:

.github/workflows/publish-pypi.yml

@@ -22,7 +22,7 @@ jobs:
       id-token: write
     steps:
       - name: "Install uv"
-        uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+        uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
       - uses: actions/download-artifact@634f93cb2916e3fdff6788551b99b062d0335ce0 # v5.0.0
         with:
           pattern: wheels-*

.github/workflows/release.yml

@@ -60,7 +60,7 @@ jobs:
     env:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     steps:
-      - uses: actions/checkout@ff7abcd0c3c05ccf6adc123a8cd1fd4fb30fb493
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
         with:
           persist-credentials: false
           submodules: recursive
@@ -123,7 +123,7 @@ jobs:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       BUILD_MANIFEST_NAME: target/distrib/global-dist-manifest.json
     steps:
-      - uses: actions/checkout@ff7abcd0c3c05ccf6adc123a8cd1fd4fb30fb493
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
         with:
           persist-credentials: false
           submodules: recursive
@@ -174,7 +174,7 @@ jobs:
     outputs:
       val: ${{ steps.host.outputs.manifest }}
     steps:
-      - uses: actions/checkout@ff7abcd0c3c05ccf6adc123a8cd1fd4fb30fb493
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
         with:
           persist-credentials: false
           submodules: recursive
@@ -250,7 +250,7 @@ jobs:
     env:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     steps:
-      - uses: actions/checkout@ff7abcd0c3c05ccf6adc123a8cd1fd4fb30fb493
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
         with:
           persist-credentials: false
           submodules: recursive

.github/workflows/sync_typeshed.yaml

@@ -77,7 +77,7 @@ jobs:
         run: |
           git config --global user.name typeshedbot
           git config --global user.email '<>'
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
       - name: Sync typeshed stubs
         run: |
           rm -rf "ruff/${VENDORED_TYPESHED}"
@@ -131,7 +131,7 @@ jobs:
         with:
           persist-credentials: true
           ref: ${{ env.UPSTREAM_BRANCH}}
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
       - name: Setup git
         run: |
           git config --global user.name typeshedbot
@@ -170,7 +170,7 @@ jobs:
         with:
           persist-credentials: true
           ref: ${{ env.UPSTREAM_BRANCH}}
-      - uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+      - uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
       - name: Setup git
         run: |
           git config --global user.name typeshedbot
@@ -207,12 +207,12 @@ jobs:
         uses: rui314/setup-mold@725a8794d15fc7563f59595bd9556495c0564878 # v1
       - name: "Install cargo nextest"
         if: ${{ success() }}
-        uses: taiki-e/install-action@537c30d2b45cc3aa3fb35e2bbcfb61ef93fd6f02 # v2.62.52
+        uses: taiki-e/install-action@f79fe7514db78f0a7bdba3cb6dd9c1baa7d046d9 # v2.62.56
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
         if: ${{ success() }}
-        uses: taiki-e/install-action@537c30d2b45cc3aa3fb35e2bbcfb61ef93fd6f02 # v2.62.52
+        uses: taiki-e/install-action@f79fe7514db78f0a7bdba3cb6dd9c1baa7d046d9 # v2.62.56
         with:
           tool: cargo-insta
       - name: Update snapshots

.github/workflows/ty-ecosystem-analyzer.yaml

@@ -33,7 +33,7 @@ jobs:
           persist-credentials: false
 
       - name: Install the latest version of uv
-        uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+        uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
         with:
           enable-cache: true # zizmor: ignore[cache-poisoning] acceptable risk for CloudFlare pages artifact
 
@@ -67,7 +67,7 @@ jobs:
 
           cd ..
 
-          uv tool install "git+https://github.com/astral-sh/ecosystem-analyzer@e5c5f5b2d762af91b28490537fe0077334165693"
+          uv tool install "git+https://github.com/astral-sh/ecosystem-analyzer@e26ebfb78d372b8b091e1cb1d6fc522e135474c1"
 
           ecosystem-analyzer \
             --repository ruff \

.github/workflows/ty-ecosystem-report.yaml

@@ -29,7 +29,7 @@ jobs:
           persist-credentials: false
 
       - name: Install the latest version of uv
-        uses: astral-sh/setup-uv@5a7eac68fb9809dea845d802897dc5c723910fa3 # v7.1.3
+        uses: astral-sh/setup-uv@1e862dfacbd1d6d858c55d9b792c756523627244 # v7.1.4
         with:
           enable-cache: true # zizmor: ignore[cache-poisoning] acceptable risk for CloudFlare pages artifact
 
@@ -52,7 +52,7 @@ jobs:
 
           cd ..
 
-          uv tool install "git+https://github.com/astral-sh/ecosystem-analyzer@e5c5f5b2d762af91b28490537fe0077334165693"
+          uv tool install "git+https://github.com/astral-sh/ecosystem-analyzer@e26ebfb78d372b8b091e1cb1d6fc522e135474c1"
 
           ecosystem-analyzer \
             --verbose \

CHANGELOG.md

@@ -1,5 +1,48 @@
 # Changelog
 
+## 0.14.6
+
+Released on 2025-11-21.
+
+### Preview features
+
+- \[`flake8-bandit`\] Support new PySNMP API paths (`S508`, `S509`) ([#21374](https://github.com/astral-sh/ruff/pull/21374))
+
+### Bug fixes
+
+- Adjust own-line comment placement between branches ([#21185](https://github.com/astral-sh/ruff/pull/21185))
+- Avoid syntax error when formatting attribute expressions with outer parentheses, parenthesized value, and trailing comment on value ([#20418](https://github.com/astral-sh/ruff/pull/20418))
+- Fix panic when formatting comments in unary expressions ([#21501](https://github.com/astral-sh/ruff/pull/21501))
+- Respect `fmt: skip` for compound statements on a single line ([#20633](https://github.com/astral-sh/ruff/pull/20633))
+- \[`refurb`\] Fix `FURB103` autofix ([#21454](https://github.com/astral-sh/ruff/pull/21454))
+- \[`ruff`\] Fix false positive for complex conversion specifiers in `logging-eager-conversion` (`RUF065`) ([#21464](https://github.com/astral-sh/ruff/pull/21464))
+
+### Rule changes
+
+- \[`ruff`\] Avoid false positive on `ClassVar` reassignment (`RUF012`) ([#21478](https://github.com/astral-sh/ruff/pull/21478))
+
+### CLI
+
+- Render hyperlinks for lint errors ([#21514](https://github.com/astral-sh/ruff/pull/21514))
+- Add a `ruff analyze` option to skip over imports in `TYPE_CHECKING` blocks ([#21472](https://github.com/astral-sh/ruff/pull/21472))
+
+### Documentation
+
+- Limit `eglot-format` hook to eglot-managed Python buffers ([#21459](https://github.com/astral-sh/ruff/pull/21459))
+- Mention `force-exclude` in "Configuration > Python file discovery" ([#21500](https://github.com/astral-sh/ruff/pull/21500))
+
+### Contributors
+
+- [@ntBre](https://github.com/ntBre)
+- [@dylwil3](https://github.com/dylwil3)
+- [@gauthsvenkat](https://github.com/gauthsvenkat)
+- [@MichaReiser](https://github.com/MichaReiser)
+- [@thamer](https://github.com/thamer)
+- [@Ruchir28](https://github.com/Ruchir28)
+- [@thejcannon](https://github.com/thejcannon)
+- [@danparizher](https://github.com/danparizher)
+- [@chirizxc](https://github.com/chirizxc)
+
 ## 0.14.5
 
 Released on 2025-11-13.

Cargo.lock

@@ -442,9 +442,9 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.5.51"
+version = "4.5.53"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4c26d721170e0295f191a69bd9a1f93efcdb0aff38684b61ab5750468972e5f5"
+checksum = "c9e340e012a1bf4935f5282ed1436d1489548e8f72308207ea5df0e23d2d03f8"
 dependencies = [
  "clap_builder",
  "clap_derive",
@@ -452,9 +452,9 @@ dependencies = [
 
 [[package]]
 name = "clap_builder"
-version = "4.5.51"
+version = "4.5.53"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "75835f0c7bf681bfd05abe44e965760fea999a5286c6eb2d59883634fd02011a"
+checksum = "d76b5d13eaa18c901fd2f7fca939fefe3a0727a953561fefdf3b2922b8569d00"
 dependencies = [
  "anstream",
  "anstyle",
@@ -1016,7 +1016,7 @@ dependencies = [
  "libc",
  "option-ext",
  "redox_users",
- "windows-sys 0.61.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -1108,7 +1108,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
 dependencies = [
  "libc",
- "windows-sys 0.61.0",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -1255,7 +1255,7 @@ checksum = "ac7bb8710e1f09672102be7ddf39f764d8440ae74a9f4e30aaa4820dcdffa4af"
 dependencies = [
  "compact_str",
  "get-size-derive2",
- "hashbrown 0.16.0",
+ "hashbrown 0.16.1",
  "indexmap",
  "smallvec",
 ]
@@ -1353,9 +1353,9 @@ dependencies = [
 
 [[package]]
 name = "hashbrown"
-version = "0.16.0"
+version = "0.16.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5419bdc4f6a9207fbeba6d11b604d481addf78ecd10c11ad51e76c2f6482748d"
+checksum = "841d1cc9bed7f9236f321df977030373f4a4163ae1a7dbfe1a51a2c1a51d9100"
 dependencies = [
  "equivalent",
 ]
@@ -1564,12 +1564,12 @@ dependencies = [
 
 [[package]]
 name = "indexmap"
-version = "2.12.0"
+version = "2.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6717a8d2a5a929a1a2eb43a12812498ed141a0bcfb7e8f7844fbdbe4303bba9f"
+checksum = "0ad4bb2b565bca0645f4d68c5c9af97fba094e9791da685bf83cb5f3ce74acf2"
 dependencies = [
  "equivalent",
- "hashbrown 0.16.0",
+ "hashbrown 0.16.1",
  "serde",
  "serde_core",
 ]
@@ -1763,7 +1763,7 @@ dependencies = [
  "portable-atomic",
  "portable-atomic-util",
  "serde_core",
- "windows-sys 0.61.0",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -2859,7 +2859,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.14.5"
+version = "0.14.6"
 dependencies = [
  "anyhow",
  "argfile",
@@ -3117,7 +3117,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_linter"
-version = "0.14.5"
+version = "0.14.6"
 dependencies = [
  "aho-corasick",
  "anyhow",
@@ -3127,7 +3127,7 @@ dependencies = [
  "fern",
  "glob",
  "globset",
- "hashbrown 0.16.0",
+ "hashbrown 0.16.1",
  "imperative",
  "insta",
  "is-macro",
@@ -3472,7 +3472,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_wasm"
-version = "0.14.5"
+version = "0.14.6"
 dependencies = [
  "console_error_panic_hook",
  "console_log",
@@ -3570,7 +3570,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys",
- "windows-sys 0.61.0",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -3588,7 +3588,7 @@ checksum = "28d3b2b1366ec20994f1fd18c3c594f05c5dd4bc44d8bb0c1c632c8d6829481f"
 [[package]]
 name = "salsa"
 version = "0.24.0"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=a885bb4c4c192741b8a17418fef81a71e33d111e#a885bb4c4c192741b8a17418fef81a71e33d111e"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=17bc55d699565e5a1cb1bd42363b905af2f9f3e7#17bc55d699565e5a1cb1bd42363b905af2f9f3e7"
 dependencies = [
  "boxcar",
  "compact_str",
@@ -3612,12 +3612,12 @@ dependencies = [
 [[package]]
 name = "salsa-macro-rules"
 version = "0.24.0"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=a885bb4c4c192741b8a17418fef81a71e33d111e#a885bb4c4c192741b8a17418fef81a71e33d111e"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=17bc55d699565e5a1cb1bd42363b905af2f9f3e7#17bc55d699565e5a1cb1bd42363b905af2f9f3e7"
 
 [[package]]
 name = "salsa-macros"
 version = "0.24.0"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=a885bb4c4c192741b8a17418fef81a71e33d111e#a885bb4c4c192741b8a17418fef81a71e33d111e"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=17bc55d699565e5a1cb1bd42363b905af2f9f3e7#17bc55d699565e5a1cb1bd42363b905af2f9f3e7"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -3935,9 +3935,9 @@ checksum = "804f44ed3c63152de6a9f90acbea1a110441de43006ea51bcce8f436196a288b"
 
 [[package]]
 name = "syn"
-version = "2.0.110"
+version = "2.0.111"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a99801b5bd34ede4cf3fc688c5919368fea4e4814a4664359503e6015b280aea"
+checksum = "390cc9a294ab71bdb1aa2e99d13be9c753cd2d7bd6560c77118597410c4d2e87"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -3971,7 +3971,7 @@ dependencies = [
  "getrandom 0.3.4",
  "once_cell",
  "rustix",
- "windows-sys 0.61.0",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -4462,7 +4462,7 @@ dependencies = [
  "drop_bomb",
  "get-size2",
  "glob",
- "hashbrown 0.16.0",
+ "hashbrown 0.16.1",
  "indexmap",
  "indoc",
  "insta",
@@ -5020,7 +5020,7 @@ version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c2a7b1c03c876122aa43f3020e6c3c3ee5c05081c9a00739faf7503aeba10d22"
 dependencies = [
- "windows-sys 0.61.0",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]

Cargo.toml

@@ -146,7 +146,7 @@ regex-automata = { version = "0.4.9" }
 rustc-hash = { version = "2.0.0" }
 rustc-stable-hash = { version = "0.1.2" }
 # When updating salsa, make sure to also update the revision in `fuzz/Cargo.toml`
-salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "a885bb4c4c192741b8a17418fef81a71e33d111e", default-features = false, features = [
+salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "17bc55d699565e5a1cb1bd42363b905af2f9f3e7", default-features = false, features = [
     "compact_str",
     "macros",
     "salsa_unstable",

README.md

@@ -147,8 +147,8 @@ 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/0.14.5/install.sh | sh
-powershell -c "irm https://astral.sh/ruff/0.14.5/install.ps1 | iex"
+curl -LsSf https://astral.sh/ruff/0.14.6/install.sh | sh
+powershell -c "irm https://astral.sh/ruff/0.14.6/install.ps1 | iex"
 ```
 
 You can also install Ruff via [Homebrew](https://formulae.brew.sh/formula/ruff), [Conda](https://anaconda.org/conda-forge/ruff),
@@ -181,7 +181,7 @@ 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: v0.14.5
+  rev: v0.14.6
   hooks:
     # Run the linter.
     - id: ruff-check

crates/ruff/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff"
-version = "0.14.5"
+version = "0.14.6"
 publish = true
 authors = { workspace = true }
 edition = { workspace = true }

crates/ruff_benchmark/Cargo.toml

@@ -59,8 +59,6 @@ divan = { workspace = true, optional = true }
 anyhow = { workspace = true }
 codspeed-criterion-compat = { workspace = true, default-features = false, optional = true }
 criterion = { workspace = true, default-features = false, optional = true }
-rayon = { workspace = true }
-rustc-hash = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 tracing = { workspace = true }
@@ -88,3 +86,7 @@ mimalloc = { workspace = true }
 
 [target.'cfg(all(not(target_os = "windows"), not(target_os = "openbsd"), any(target_arch = "x86_64", target_arch = "aarch64", target_arch = "powerpc64", target_arch = "riscv64")))'.dev-dependencies]
 tikv-jemallocator = { workspace = true }
+
+[dev-dependencies]
+rustc-hash = { workspace = true }
+rayon = { workspace = true }

crates/ruff_benchmark/benches/ty_walltime.rs

@@ -143,7 +143,7 @@ static FREQTRADE: Benchmark = Benchmark::new(
         max_dep_date: "2025-06-17",
         python_version: PythonVersion::PY312,
     },
-    525,
+    600,
 );
 
 static PANDAS: Benchmark = Benchmark::new(
@@ -163,7 +163,7 @@ static PANDAS: Benchmark = Benchmark::new(
         max_dep_date: "2025-06-17",
         python_version: PythonVersion::PY312,
     },
-    3000,
+    4000,
 );
 
 static PYDANTIC: Benchmark = Benchmark::new(
@@ -181,7 +181,7 @@ static PYDANTIC: Benchmark = Benchmark::new(
         max_dep_date: "2025-06-17",
         python_version: PythonVersion::PY39,
     },
-    5000,
+    7000,
 );
 
 static SYMPY: Benchmark = Benchmark::new(

crates/ruff_linter/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff_linter"
-version = "0.14.5"
+version = "0.14.6"
 publish = false
 authors = { workspace = true }
 edition = { workspace = true }

crates/ruff_linter/resources/test/fixtures/flake8_implicit_str_concat/ISC.py

@@ -208,3 +208,17 @@ _ = t"b {f"c" f"d {t"e" t"f"} g"} h"
 _ = f"b {t"abc" \
     t"def"} g"
 
+
+# Explicit concatenation with either operand being
+# a string literal that wraps across multiple lines (in parentheses)
+# reports diagnostic - no autofix.
+# See https://github.com/astral-sh/ruff/issues/19757
+_ = "abc" + (
+    "def"
+    "ghi"
+)
+
+_ = (
+    "abc"
+    "def"
+) + "ghi"

crates/ruff_linter/resources/test/fixtures/pylint/dict_iter_missing_items.py

@@ -30,3 +30,23 @@ for a, b in d_tuple:
     pass
 for a, b in d_tuple_annotated: 
     pass
+
+# Empty dict cases
+empty_dict = {}
+empty_dict["x"] = 1
+for k, v in empty_dict:
+    pass
+
+empty_dict_annotated_tuple_keys: dict[tuple[int, str], bool] = {}
+for k, v in empty_dict_annotated_tuple_keys:
+    pass
+
+empty_dict_unannotated = {}
+empty_dict_unannotated[("x", "y")] = True
+for k, v in empty_dict_unannotated:
+    pass
+
+empty_dict_annotated_str_keys: dict[str, int] = {}
+empty_dict_annotated_str_keys["x"] = 1
+for k, v in empty_dict_annotated_str_keys:
+    pass

crates/ruff_linter/resources/test/fixtures/pylint/stop_iteration_return.py

@@ -129,3 +129,26 @@ def generator_with_lambda():
     yield 1
     func = lambda x: x  # Just a regular lambda
     yield 2
+
+# See: https://github.com/astral-sh/ruff/issues/21162
+def foo():
+    def g():
+        yield 1
+    raise StopIteration  # Should not trigger
+
+
+def foo():
+    def g():
+        raise StopIteration  # Should not trigger
+    yield 1
+
+# https://github.com/astral-sh/ruff/pull/21177#pullrequestreview-3430209718
+def foo():
+    yield 1
+    class C:
+        raise StopIteration  # Should trigger
+    yield C
+
+# https://github.com/astral-sh/ruff/pull/21177#discussion_r2539702728
+def foo():
+    raise StopIteration((yield 1))  # Should trigger

crates/ruff_linter/resources/test/fixtures/ruff/RUF052_1.py

@@ -0,0 +1,109 @@
+# Correct usage in loop and comprehension
+def process_data():
+    return 42
+def test_correct_dummy_usage():
+    my_list = [{"foo": 1}, {"foo": 2}]
+
+    # Should NOT detect - dummy variable is not used
+    [process_data() for _ in my_list]  # OK: `_` is ignored by rule
+
+    # Should NOT detect - dummy variable is not used
+    [item["foo"] for item in my_list]  # OK: not a dummy variable name
+
+    # Should NOT detect - dummy variable is not used
+    [42 for _unused in my_list]  # OK: `_unused` is not accessed
+
+# Regular For Loops
+def test_for_loops():
+    my_list = [{"foo": 1}, {"foo": 2}]
+
+    # Should detect used dummy variable
+    for _item in my_list:
+        print(_item["foo"])  # RUF052: Local dummy variable `_item` is accessed
+
+    # Should detect used dummy variable
+    for _index, _value in enumerate(my_list):
+        result = _index + _value["foo"]  # RUF052: Both `_index` and `_value` are accessed
+
+# List Comprehensions
+def test_list_comprehensions():
+    my_list = [{"foo": 1}, {"foo": 2}]
+
+    # Should detect used dummy variable
+    result = [_item["foo"] for _item in my_list]  # RUF052: Local dummy variable `_item` is accessed
+
+    # Should detect used dummy variable in nested comprehension
+    nested = [[_item["foo"] for _item in _sublist] for _sublist in [my_list, my_list]]
+    # RUF052: Both `_item` and `_sublist` are accessed
+
+    # Should detect with conditions
+    filtered = [_item["foo"] for _item in my_list if _item["foo"] > 0]
+    # RUF052: Local dummy variable `_item` is accessed
+
+# Dict Comprehensions
+def test_dict_comprehensions():
+    my_list = [{"key": "a", "value": 1}, {"key": "b", "value": 2}]
+
+    # Should detect used dummy variable
+    result = {_item["key"]: _item["value"] for _item in my_list}
+    # RUF052: Local dummy variable `_item` is accessed
+
+    # Should detect with enumerate
+    indexed = {_index: _item["value"] for _index, _item in enumerate(my_list)}
+    # RUF052: Both `_index` and `_item` are accessed
+
+    # Should detect in nested dict comprehension
+    nested = {_outer: {_inner["key"]: _inner["value"] for _inner in sublist}
+              for _outer, sublist in enumerate([my_list])}
+    # RUF052: `_outer`, `_inner` are accessed
+
+# Set Comprehensions
+def test_set_comprehensions():
+    my_list = [{"foo": 1}, {"foo": 2}, {"foo": 1}]  # Note: duplicate values
+
+    # Should detect used dummy variable
+    unique_values = {_item["foo"] for _item in my_list}
+    # RUF052: Local dummy variable `_item` is accessed
+
+    # Should detect with conditions
+    filtered_set = {_item["foo"] for _item in my_list if _item["foo"] > 0}
+    # RUF052: Local dummy variable `_item` is accessed
+
+    # Should detect with complex expression
+    processed = {_item["foo"] * 2 for _item in my_list}
+    # RUF052: Local dummy variable `_item` is accessed
+
+# Generator Expressions
+def test_generator_expressions():
+    my_list = [{"foo": 1}, {"foo": 2}]
+
+    # Should detect used dummy variable
+    gen = (_item["foo"] for _item in my_list)
+    # RUF052: Local dummy variable `_item` is accessed
+
+    # Should detect when passed to function
+    total = sum(_item["foo"] for _item in my_list)
+    # RUF052: Local dummy variable `_item` is accessed
+
+    # Should detect with multiple generators
+    pairs = ((_x, _y) for _x in range(3) for _y in range(3) if _x != _y)
+    # RUF052: Both `_x` and `_y` are accessed
+
+    # Should detect in nested generator
+    nested_gen = (sum(_inner["foo"] for _inner in sublist) for _sublist in [my_list] for sublist in _sublist)
+    # RUF052: `_inner` and `_sublist` are accessed
+
+# Complex Examples with Multiple Comprehension Types
+def test_mixed_comprehensions():
+    data = [{"items": [1, 2, 3]}, {"items": [4, 5, 6]}]
+
+    # Should detect in mixed comprehensions
+    result = [
+        {_key: [_val * 2 for _val in _record["items"]] for _key in ["doubled"]}
+        for _record in data
+    ]
+    # RUF052: `_key`, `_val`, and `_record` are all accessed
+
+    # Should detect in generator passed to list constructor
+    gen_list = list(_item["items"][0] for _item in data)
+    # RUF052: Local dummy variable `_item` is accessed

crates/ruff_linter/src/checkers/ast/analyze/statement.rs

@@ -131,6 +131,9 @@ pub(crate) fn statement(stmt: &Stmt, checker: &mut Checker) {
             if checker.is_rule_enabled(Rule::GeneratorReturnFromIterMethod) {
                 flake8_pyi::rules::bad_generator_return_type(function_def, checker);
             }
+            if checker.is_rule_enabled(Rule::StopIterationReturn) {
+                pylint::rules::stop_iteration_return(checker, function_def);
+            }
             if checker.source_type.is_stub() {
                 if checker.is_rule_enabled(Rule::StrOrReprDefinedInStub) {
                     flake8_pyi::rules::str_or_repr_defined_in_stub(checker, stmt);
@@ -950,9 +953,6 @@ pub(crate) fn statement(stmt: &Stmt, checker: &mut Checker) {
             if checker.is_rule_enabled(Rule::MisplacedBareRaise) {
                 pylint::rules::misplaced_bare_raise(checker, raise);
             }
-            if checker.is_rule_enabled(Rule::StopIterationReturn) {
-                pylint::rules::stop_iteration_return(checker, raise);
-            }
         }
         Stmt::AugAssign(aug_assign @ ast::StmtAugAssign { target, .. }) => {
             if checker.is_rule_enabled(Rule::GlobalStatement) {

crates/ruff_linter/src/rules/flake8_implicit_str_concat/rules/explicit.rs

@@ -1,12 +1,12 @@
 use ruff_macros::{ViolationMetadata, derive_message_formats};
+use ruff_python_ast::parenthesize::parenthesized_range;
 use ruff_python_ast::{self as ast, Expr, Operator};
 use ruff_python_trivia::is_python_whitespace;
 use ruff_source_file::LineRanges;
 use ruff_text_size::{Ranged, TextLen, TextRange, TextSize};
 
-use crate::AlwaysFixableViolation;
 use crate::checkers::ast::Checker;
-use crate::{Edit, Fix};
+use crate::{Edit, Fix, FixAvailability, Violation};
 
 /// ## What it does
 /// Checks for string literals that are explicitly concatenated (using the
@@ -36,14 +36,16 @@ use crate::{Edit, Fix};
 #[violation_metadata(stable_since = "v0.0.201")]
 pub(crate) struct ExplicitStringConcatenation;
 
-impl AlwaysFixableViolation for ExplicitStringConcatenation {
+impl Violation for ExplicitStringConcatenation {
+    const FIX_AVAILABILITY: FixAvailability = FixAvailability::Sometimes;
+
     #[derive_message_formats]
     fn message(&self) -> String {
         "Explicitly concatenated string should be implicitly concatenated".to_string()
     }
 
-    fn fix_title(&self) -> String {
-        "Remove redundant '+' operator to implicitly concatenate".to_string()
+    fn fix_title(&self) -> Option<String> {
+        Some("Remove redundant '+' operator to implicitly concatenate".to_string())
     }
 }
 
@@ -82,9 +84,27 @@ pub(crate) fn explicit(checker: &Checker, expr: &Expr) {
                     .locator()
                     .contains_line_break(TextRange::new(left.end(), right.start()))
             {
-                checker
-                    .report_diagnostic(ExplicitStringConcatenation, expr.range())
-                    .set_fix(generate_fix(checker, bin_op));
+                let mut diagnostic =
+                    checker.report_diagnostic(ExplicitStringConcatenation, expr.range());
+
+                let is_parenthesized = |expr: &Expr| {
+                    parenthesized_range(
+                        expr.into(),
+                        bin_op.into(),
+                        checker.comment_ranges(),
+                        checker.source(),
+                    )
+                    .is_some()
+                };
+                // If either `left` or `right` is parenthesized, generating
+                // a fix would be too involved. Just report the diagnostic.
+                // Currently, attempting `generate_fix` would result in
+                // an invalid code. See: #19757
+                if is_parenthesized(left) || is_parenthesized(right) {
+                    return;
+                }
+
+                diagnostic.set_fix(generate_fix(checker, bin_op));
             }
         }
     }

crates/ruff_linter/src/rules/flake8_implicit_str_concat/snapshots/ruff_linter__rules__flake8_implicit_str_concat__tests__ISC003_ISC.py.snap

@@ -357,3 +357,33 @@ help: Remove redundant '+' operator to implicitly concatenate
 203 | )
 204 | 
 205 | # nested examples with both t and f-strings
+
+ISC003 Explicitly concatenated string should be implicitly concatenated
+   --> ISC.py:216:5
+    |
+214 |   # reports diagnostic - no autofix.
+215 |   # See https://github.com/astral-sh/ruff/issues/19757
+216 |   _ = "abc" + (
+    |  _____^
+217 | |     "def"
+218 | |     "ghi"
+219 | | )
+    | |_^
+220 |
+221 |   _ = (
+    |
+help: Remove redundant '+' operator to implicitly concatenate
+
+ISC003 Explicitly concatenated string should be implicitly concatenated
+   --> ISC.py:221:5
+    |
+219 |   )
+220 |
+221 |   _ = (
+    |  _____^
+222 | |     "abc"
+223 | |     "def"
+224 | | ) + "ghi"
+    | |_________^
+    |
+help: Remove redundant '+' operator to implicitly concatenate

crates/ruff_linter/src/rules/flake8_implicit_str_concat/snapshots/ruff_linter__rules__flake8_implicit_str_concat__tests__multiline_ISC002_ISC.py.snap

@@ -89,3 +89,24 @@ ISC002 Implicitly concatenated string literals over multiple lines
 209 | |     t"def"} g"
     | |__________^
     |
+
+ISC002 Implicitly concatenated string literals over multiple lines
+   --> ISC.py:217:5
+    |
+215 |   # See https://github.com/astral-sh/ruff/issues/19757
+216 |   _ = "abc" + (
+217 | /     "def"
+218 | |     "ghi"
+    | |_________^
+219 |   )
+    |
+
+ISC002 Implicitly concatenated string literals over multiple lines
+   --> ISC.py:222:5
+    |
+221 |   _ = (
+222 | /     "abc"
+223 | |     "def"
+    | |_________^
+224 |   ) + "ghi"
+    |

crates/ruff_linter/src/rules/pylint/rules/dict_iter_missing_items.rs

@@ -1,4 +1,4 @@
-use ruff_python_ast::{Expr, Stmt};
+use ruff_python_ast::{self as ast, Expr, Stmt};
 
 use ruff_macros::{ViolationMetadata, derive_message_formats};
 use ruff_python_semantic::analyze::typing::is_dict;
@@ -108,15 +108,77 @@ fn is_dict_key_tuple_with_two_elements(binding: &Binding, semantic: &SemanticMod
         return false;
     };
 
-    let Stmt::Assign(assign_stmt) = statement else {
+    let (value, annotation) = match statement {
+        Stmt::Assign(assign_stmt) => (assign_stmt.value.as_ref(), None),
+        Stmt::AnnAssign(ast::StmtAnnAssign {
+            value: Some(value),
+            annotation,
+            ..
+        }) => (value.as_ref(), Some(annotation.as_ref())),
+        _ => return false,
+    };
+
+    let Expr::Dict(dict_expr) = value else {
         return false;
     };
 
-    let Expr::Dict(dict_expr) = &*assign_stmt.value else {
-        return false;
-    };
+    // Check if dict is empty
+    let is_empty = dict_expr.is_empty();
 
+    if is_empty {
+        // For empty dicts, check type annotation
+        return annotation
+            .is_some_and(|annotation| is_annotation_dict_with_tuple_keys(annotation, semantic));
+    }
+
+    // For non-empty dicts, check if all keys are 2-tuples
     dict_expr
         .iter_keys()
         .all(|key| matches!(key, Some(Expr::Tuple(tuple)) if tuple.len() == 2))
 }
+
+/// Returns true if the annotation is `dict[tuple[T1, T2], ...]` where tuple has exactly 2 elements.
+fn is_annotation_dict_with_tuple_keys(annotation: &Expr, semantic: &SemanticModel) -> bool {
+    // Check if it's a subscript: dict[...]
+    let Expr::Subscript(subscript) = annotation else {
+        return false;
+    };
+
+    // Check if it's dict or typing.Dict
+    if !semantic.match_builtin_expr(subscript.value.as_ref(), "dict")
+        && !semantic.match_typing_expr(subscript.value.as_ref(), "Dict")
+    {
+        return false;
+    }
+
+    // Extract the slice (should be a tuple: (key_type, value_type))
+    let Expr::Tuple(tuple) = subscript.slice.as_ref() else {
+        return false;
+    };
+
+    // dict[K, V] format - check if K is tuple with 2 elements
+    if let [key, _value] = tuple.elts.as_slice() {
+        return is_tuple_type_with_two_elements(key, semantic);
+    }
+
+    false
+}
+
+/// Returns true if the expression represents a tuple type with exactly 2 elements.
+fn is_tuple_type_with_two_elements(expr: &Expr, semantic: &SemanticModel) -> bool {
+    // Handle tuple[...] subscript
+    if let Expr::Subscript(subscript) = expr {
+        // Check if it's tuple or typing.Tuple
+        if semantic.match_builtin_expr(subscript.value.as_ref(), "tuple")
+            || semantic.match_typing_expr(subscript.value.as_ref(), "Tuple")
+        {
+            // Check the slice - tuple[T1, T2]
+            if let Expr::Tuple(tuple_slice) = subscript.slice.as_ref() {
+                return tuple_slice.elts.len() == 2;
+            }
+            return false;
+        }
+    }
+
+    false
+}

crates/ruff_linter/src/rules/pylint/rules/stop_iteration_return.rs

@@ -1,6 +1,9 @@
 use ruff_macros::{ViolationMetadata, derive_message_formats};
-use ruff_python_ast as ast;
-use ruff_python_ast::visitor::{Visitor, walk_expr, walk_stmt};
+use ruff_python_ast::{
+    self as ast,
+    helpers::map_callable,
+    visitor::{Visitor, walk_expr, walk_stmt},
+};
 use ruff_text_size::Ranged;
 
 use crate::Violation;
@@ -50,65 +53,54 @@ impl Violation for StopIterationReturn {
 }
 
 /// PLR1708
-pub(crate) fn stop_iteration_return(checker: &Checker, raise_stmt: &ast::StmtRaise) {
-    // Fast-path: only continue if this is `raise StopIteration` (with or without args)
-    let Some(exc) = &raise_stmt.exc else {
-        return;
+pub(crate) fn stop_iteration_return(checker: &Checker, function_def: &ast::StmtFunctionDef) {
+    let mut analyzer = GeneratorAnalyzer {
+        checker,
+        has_yield: false,
+        stop_iteration_raises: Vec::new(),
     };
 
-    let is_stop_iteration = match exc.as_ref() {
-        ast::Expr::Call(ast::ExprCall { func, .. }) => {
-            checker.semantic().match_builtin_expr(func, "StopIteration")
+    analyzer.visit_body(&function_def.body);
+
+    if analyzer.has_yield {
+        for raise_stmt in analyzer.stop_iteration_raises {
+            checker.report_diagnostic(StopIterationReturn, raise_stmt.range());
         }
-        expr => checker.semantic().match_builtin_expr(expr, "StopIteration"),
-    };
-
-    if !is_stop_iteration {
-        return;
     }
-
-    // Now check the (more expensive) generator context
-    if !in_generator_context(checker) {
-        return;
-    }
-
-    checker.report_diagnostic(StopIterationReturn, raise_stmt.range());
 }
 
-/// Returns true if we're inside a function that contains any `yield`/`yield from`.
-fn in_generator_context(checker: &Checker) -> bool {
-    for scope in checker.semantic().current_scopes() {
-        if let ruff_python_semantic::ScopeKind::Function(function_def) = scope.kind {
-            if contains_yield_statement(&function_def.body) {
-                return true;
+struct GeneratorAnalyzer<'a, 'b> {
+    checker: &'a Checker<'b>,
+    has_yield: bool,
+    stop_iteration_raises: Vec<&'a ast::StmtRaise>,
+}
+
+impl<'a> Visitor<'a> for GeneratorAnalyzer<'a, '_> {
+    fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
+        match stmt {
+            ast::Stmt::FunctionDef(_) => {}
+            ast::Stmt::Raise(raise @ ast::StmtRaise { exc: Some(exc), .. }) => {
+                if self
+                    .checker
+                    .semantic()
+                    .match_builtin_expr(map_callable(exc), "StopIteration")
+                {
+                    self.stop_iteration_raises.push(raise);
+                }
+                walk_stmt(self, stmt);
             }
+            _ => walk_stmt(self, stmt),
         }
     }
-    false
-}
 
-/// Check if a statement list contains any yield statements
-fn contains_yield_statement(body: &[ast::Stmt]) -> bool {
-    struct YieldFinder {
-        found: bool,
-    }
-
-    impl Visitor<'_> for YieldFinder {
-        fn visit_expr(&mut self, expr: &ast::Expr) {
-            if matches!(expr, ast::Expr::Yield(_) | ast::Expr::YieldFrom(_)) {
-                self.found = true;
-            } else {
+    fn visit_expr(&mut self, expr: &'a ast::Expr) {
+        match expr {
+            ast::Expr::Lambda(_) => {}
+            ast::Expr::Yield(_) | ast::Expr::YieldFrom(_) => {
+                self.has_yield = true;
                 walk_expr(self, expr);
             }
+            _ => walk_expr(self, expr),
         }
     }
-
-    let mut finder = YieldFinder { found: false };
-    for stmt in body {
-        walk_stmt(&mut finder, stmt);
-        if finder.found {
-            return true;
-        }
-    }
-    false
 }

crates/ruff_linter/src/rules/pylint/snapshots/ruff_linter__rules__pylint__tests__PLE1141_dict_iter_missing_items.py.snap

@@ -39,3 +39,61 @@ help: Add a call to `.items()`
 18 | 
 19 | 
 note: This is an unsafe fix and may change runtime behavior
+
+PLE1141 [*] Unpacking a dictionary in iteration without calling `.items()`
+  --> dict_iter_missing_items.py:37:13
+   |
+35 | empty_dict = {}
+36 | empty_dict["x"] = 1
+37 | for k, v in empty_dict:
+   |             ^^^^^^^^^^
+38 |     pass
+   |
+help: Add a call to `.items()`
+34 | # Empty dict cases
+35 | empty_dict = {}
+36 | empty_dict["x"] = 1
+   - for k, v in empty_dict:
+37 + for k, v in empty_dict.items():
+38 |     pass
+39 | 
+40 | empty_dict_annotated_tuple_keys: dict[tuple[int, str], bool] = {}
+note: This is an unsafe fix and may change runtime behavior
+
+PLE1141 [*] Unpacking a dictionary in iteration without calling `.items()`
+  --> dict_iter_missing_items.py:46:13
+   |
+44 | empty_dict_unannotated = {}
+45 | empty_dict_unannotated[("x", "y")] = True
+46 | for k, v in empty_dict_unannotated:
+   |             ^^^^^^^^^^^^^^^^^^^^^^
+47 |     pass
+   |
+help: Add a call to `.items()`
+43 | 
+44 | empty_dict_unannotated = {}
+45 | empty_dict_unannotated[("x", "y")] = True
+   - for k, v in empty_dict_unannotated:
+46 + for k, v in empty_dict_unannotated.items():
+47 |     pass
+48 | 
+49 | empty_dict_annotated_str_keys: dict[str, int] = {}
+note: This is an unsafe fix and may change runtime behavior
+
+PLE1141 [*] Unpacking a dictionary in iteration without calling `.items()`
+  --> dict_iter_missing_items.py:51:13
+   |
+49 | empty_dict_annotated_str_keys: dict[str, int] = {}
+50 | empty_dict_annotated_str_keys["x"] = 1
+51 | for k, v in empty_dict_annotated_str_keys:
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+52 |     pass
+   |
+help: Add a call to `.items()`
+48 | 
+49 | empty_dict_annotated_str_keys: dict[str, int] = {}
+50 | empty_dict_annotated_str_keys["x"] = 1
+   - for k, v in empty_dict_annotated_str_keys:
+51 + for k, v in empty_dict_annotated_str_keys.items():
+52 |     pass
+note: This is an unsafe fix and may change runtime behavior

crates/ruff_linter/src/rules/pylint/snapshots/ruff_linter__rules__pylint__tests__PLR1708_stop_iteration_return.py.snap

@@ -107,3 +107,24 @@ PLR1708 Explicit `raise StopIteration` in generator
     |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
 help: Use `return` instead
+
+PLR1708 Explicit `raise StopIteration` in generator
+   --> stop_iteration_return.py:149:9
+    |
+147 |     yield 1
+148 |     class C:
+149 |         raise StopIteration  # Should trigger
+    |         ^^^^^^^^^^^^^^^^^^^
+150 |     yield C
+    |
+help: Use `return` instead
+
+PLR1708 Explicit `raise StopIteration` in generator
+   --> stop_iteration_return.py:154:5
+    |
+152 | # https://github.com/astral-sh/ruff/pull/21177#discussion_r2539702728
+153 | def foo():
+154 |     raise StopIteration((yield 1))  # Should trigger
+    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+    |
+help: Use `return` instead

crates/ruff_linter/src/rules/ruff/mod.rs

@@ -97,7 +97,8 @@ mod tests {
     #[test_case(Rule::MapIntVersionParsing, Path::new("RUF048_1.py"))]
     #[test_case(Rule::DataclassEnum, Path::new("RUF049.py"))]
     #[test_case(Rule::IfKeyInDictDel, Path::new("RUF051.py"))]
-    #[test_case(Rule::UsedDummyVariable, Path::new("RUF052.py"))]
+    #[test_case(Rule::UsedDummyVariable, Path::new("RUF052_0.py"))]
+    #[test_case(Rule::UsedDummyVariable, Path::new("RUF052_1.py"))]
     #[test_case(Rule::ClassWithMixedTypeVars, Path::new("RUF053.py"))]
     #[test_case(Rule::FalsyDictGetFallback, Path::new("RUF056.py"))]
     #[test_case(Rule::UnnecessaryRound, Path::new("RUF057.py"))]
@@ -621,8 +622,8 @@ mod tests {
         Ok(())
     }
 
-    #[test_case(Rule::UsedDummyVariable, Path::new("RUF052.py"), r"^_+", 1)]
-    #[test_case(Rule::UsedDummyVariable, Path::new("RUF052.py"), r"", 2)]
+    #[test_case(Rule::UsedDummyVariable, Path::new("RUF052_0.py"), r"^_+", 1)]
+    #[test_case(Rule::UsedDummyVariable, Path::new("RUF052_0.py"), r"", 2)]
     fn custom_regexp_preset(
         rule_code: Rule,
         path: &Path,

crates/ruff_linter/src/rules/ruff/rules/used_dummy_variable.rs

@@ -1,6 +1,6 @@
 use ruff_macros::{ViolationMetadata, derive_message_formats};
 use ruff_python_ast::helpers::is_dunder;
-use ruff_python_semantic::{Binding, BindingId};
+use ruff_python_semantic::{Binding, BindingId, BindingKind, ScopeKind};
 use ruff_python_stdlib::identifiers::is_identifier;
 use ruff_text_size::Ranged;
 
@@ -111,7 +111,7 @@ pub(crate) fn used_dummy_variable(checker: &Checker, binding: &Binding, binding_
         return;
     }
 
-    // We only emit the lint on variables defined via assignments.
+    // We only emit the lint on local variables.
     //
     // ## Why not also emit the lint on function parameters?
     //
@@ -127,8 +127,30 @@ pub(crate) fn used_dummy_variable(checker: &Checker, binding: &Binding, binding_
     // autofixing the diagnostic for assignments. See:
     // - <https://github.com/astral-sh/ruff/issues/14790>
     // - <https://github.com/astral-sh/ruff/issues/14799>
-    if !binding.kind.is_assignment() {
-        return;
+    match binding.kind {
+        BindingKind::Annotation
+        | BindingKind::Argument
+        | BindingKind::NamedExprAssignment
+        | BindingKind::Assignment
+        | BindingKind::LoopVar
+        | BindingKind::WithItemVar
+        | BindingKind::BoundException
+        | BindingKind::UnboundException(_) => {}
+
+        BindingKind::TypeParam
+        | BindingKind::Global(_)
+        | BindingKind::Nonlocal(_, _)
+        | BindingKind::Builtin
+        | BindingKind::ClassDefinition(_)
+        | BindingKind::FunctionDefinition(_)
+        | BindingKind::Export(_)
+        | BindingKind::FutureImport
+        | BindingKind::Import(_)
+        | BindingKind::FromImport(_)
+        | BindingKind::SubmoduleImport(_)
+        | BindingKind::Deletion
+        | BindingKind::ConditionalDeletion(_)
+        | BindingKind::DunderClassCell => return,
     }
 
     // This excludes `global` and `nonlocal` variables.
@@ -138,9 +160,12 @@ pub(crate) fn used_dummy_variable(checker: &Checker, binding: &Binding, binding_
 
     let semantic = checker.semantic();
 
-    // Only variables defined in function scopes
+    // Only variables defined in function and generator scopes
     let scope = &semantic.scopes[binding.scope];
-    if !scope.kind.is_function() {
+    if !matches!(
+        scope.kind,
+        ScopeKind::Function(_) | ScopeKind::Generator { .. }
+    ) {
         return;
     }
 

crates/ruff_linter/src/rules/ruff/snapshots/ruff_linter__rules__ruff__tests__RUF052_RUF052_0.py.snap

@@ -2,7 +2,7 @@
 source: crates/ruff_linter/src/rules/ruff/mod.rs
 ---
 RUF052 [*] Local dummy variable `_var` is accessed
-  --> RUF052.py:92:9
+  --> RUF052_0.py:92:9
    |
 90 | class Class_:
 91 |     def fun(self):
@@ -24,7 +24,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_list` is accessed
-   --> RUF052.py:99:5
+   --> RUF052_0.py:99:5
     |
  98 | def fun():
  99 |     _list = "built-in" # [RUF052]
@@ -45,7 +45,7 @@ help: Prefer using trailing underscores to avoid shadowing a built-in
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_x` is accessed
-   --> RUF052.py:106:5
+   --> RUF052_0.py:106:5
     |
 104 | def fun():
 105 |     global x
@@ -67,7 +67,7 @@ help: Prefer using trailing underscores to avoid shadowing a variable
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_x` is accessed
-   --> RUF052.py:113:5
+   --> RUF052_0.py:113:5
     |
 111 |   def bar():
 112 |     nonlocal x
@@ -90,7 +90,7 @@ help: Prefer using trailing underscores to avoid shadowing a variable
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_x` is accessed
-   --> RUF052.py:120:5
+   --> RUF052_0.py:120:5
     |
 118 | def fun():
 119 |     x = "local"
@@ -112,7 +112,7 @@ help: Prefer using trailing underscores to avoid shadowing a variable
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 Local dummy variable `_GLOBAL_1` is accessed
-   --> RUF052.py:128:5
+   --> RUF052_0.py:128:5
     |
 127 | def unfixables():
 128 |     _GLOBAL_1 = "foo"
@@ -123,7 +123,7 @@ RUF052 Local dummy variable `_GLOBAL_1` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_local` is accessed
-   --> RUF052.py:136:5
+   --> RUF052_0.py:136:5
     |
 135 |     # unfixable because the rename would shadow a local variable
 136 |     _local = "local3"  # [RUF052]
@@ -133,7 +133,7 @@ RUF052 Local dummy variable `_local` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_GLOBAL_1` is accessed
-   --> RUF052.py:140:9
+   --> RUF052_0.py:140:9
     |
 139 |     def nested():
 140 |         _GLOBAL_1 = "foo"
@@ -144,7 +144,7 @@ RUF052 Local dummy variable `_GLOBAL_1` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_local` is accessed
-   --> RUF052.py:145:9
+   --> RUF052_0.py:145:9
     |
 144 |         # unfixable because the rename would shadow a variable from the outer function
 145 |         _local = "local4"
@@ -154,7 +154,7 @@ RUF052 Local dummy variable `_local` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 [*] Local dummy variable `_P` is accessed
-   --> RUF052.py:153:5
+   --> RUF052_0.py:153:5
     |
 151 |     from collections import namedtuple
 152 |
@@ -184,7 +184,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_T` is accessed
-   --> RUF052.py:154:5
+   --> RUF052_0.py:154:5
     |
 153 |     _P = ParamSpec("_P")
 154 |     _T = TypeVar(name="_T", covariant=True, bound=int|str)
@@ -213,7 +213,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_NT` is accessed
-   --> RUF052.py:155:5
+   --> RUF052_0.py:155:5
     |
 153 |     _P = ParamSpec("_P")
 154 |     _T = TypeVar(name="_T", covariant=True, bound=int|str)
@@ -242,7 +242,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_E` is accessed
-   --> RUF052.py:156:5
+   --> RUF052_0.py:156:5
     |
 154 |     _T = TypeVar(name="_T", covariant=True, bound=int|str)
 155 |     _NT = NamedTuple("_NT", [("foo", int)])
@@ -270,7 +270,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_NT2` is accessed
-   --> RUF052.py:157:5
+   --> RUF052_0.py:157:5
     |
 155 |     _NT = NamedTuple("_NT", [("foo", int)])
 156 |     _E = Enum("_E", ["a", "b", "c"])
@@ -297,7 +297,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_NT3` is accessed
-   --> RUF052.py:158:5
+   --> RUF052_0.py:158:5
     |
 156 |     _E = Enum("_E", ["a", "b", "c"])
 157 |     _NT2 = namedtuple("_NT2", ['x', 'y', 'z'])
@@ -323,7 +323,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_DynamicClass` is accessed
-   --> RUF052.py:159:5
+   --> RUF052_0.py:159:5
     |
 157 |     _NT2 = namedtuple("_NT2", ['x', 'y', 'z'])
 158 |     _NT3 = namedtuple(typename="_NT3", field_names=['x', 'y', 'z'])
@@ -347,7 +347,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_NotADynamicClass` is accessed
-   --> RUF052.py:160:5
+   --> RUF052_0.py:160:5
     |
 158 |     _NT3 = namedtuple(typename="_NT3", field_names=['x', 'y', 'z'])
 159 |     _DynamicClass = type("_DynamicClass", (), {})
@@ -371,7 +371,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_dummy_var` is accessed
-   --> RUF052.py:182:5
+   --> RUF052_0.py:182:5
     |
 181 | def foo():
 182 |     _dummy_var = 42
@@ -396,7 +396,7 @@ help: Prefer using trailing underscores to avoid shadowing a variable
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 Local dummy variable `_dummy_var` is accessed
-   --> RUF052.py:192:5
+   --> RUF052_0.py:192:5
     |
 190 |     # Unfixable because both possible candidates for the new name are shadowed
 191 |     # in the scope of one of the references to the variable

crates/ruff_linter/src/rules/ruff/snapshots/ruff_linter__rules__ruff__tests__RUF052_RUF052_1.py.snap

@@ -0,0 +1,494 @@
+---
+source: crates/ruff_linter/src/rules/ruff/mod.rs
+---
+RUF052 [*] Local dummy variable `_item` is accessed
+  --> RUF052_1.py:21:9
+   |
+20 |     # Should detect used dummy variable
+21 |     for _item in my_list:
+   |         ^^^^^
+22 |         print(_item["foo"])  # RUF052: Local dummy variable `_item` is accessed
+   |
+help: Remove leading underscores
+18 |     my_list = [{"foo": 1}, {"foo": 2}]
+19 | 
+20 |     # Should detect used dummy variable
+   -     for _item in my_list:
+   -         print(_item["foo"])  # RUF052: Local dummy variable `_item` is accessed
+21 +     for item in my_list:
+22 +         print(item["foo"])  # RUF052: Local dummy variable `_item` is accessed
+23 | 
+24 |     # Should detect used dummy variable
+25 |     for _index, _value in enumerate(my_list):
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_index` is accessed
+  --> RUF052_1.py:25:9
+   |
+24 |     # Should detect used dummy variable
+25 |     for _index, _value in enumerate(my_list):
+   |         ^^^^^^
+26 |         result = _index + _value["foo"]  # RUF052: Both `_index` and `_value` are accessed
+   |
+help: Remove leading underscores
+22 |         print(_item["foo"])  # RUF052: Local dummy variable `_item` is accessed
+23 | 
+24 |     # Should detect used dummy variable
+   -     for _index, _value in enumerate(my_list):
+   -         result = _index + _value["foo"]  # RUF052: Both `_index` and `_value` are accessed
+25 +     for index, _value in enumerate(my_list):
+26 +         result = index + _value["foo"]  # RUF052: Both `_index` and `_value` are accessed
+27 | 
+28 | # List Comprehensions
+29 | def test_list_comprehensions():
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_value` is accessed
+  --> RUF052_1.py:25:17
+   |
+24 |     # Should detect used dummy variable
+25 |     for _index, _value in enumerate(my_list):
+   |                 ^^^^^^
+26 |         result = _index + _value["foo"]  # RUF052: Both `_index` and `_value` are accessed
+   |
+help: Remove leading underscores
+22 |         print(_item["foo"])  # RUF052: Local dummy variable `_item` is accessed
+23 | 
+24 |     # Should detect used dummy variable
+   -     for _index, _value in enumerate(my_list):
+   -         result = _index + _value["foo"]  # RUF052: Both `_index` and `_value` are accessed
+25 +     for _index, value in enumerate(my_list):
+26 +         result = _index + value["foo"]  # RUF052: Both `_index` and `_value` are accessed
+27 | 
+28 | # List Comprehensions
+29 | def test_list_comprehensions():
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_item` is accessed
+  --> RUF052_1.py:33:32
+   |
+32 |     # Should detect used dummy variable
+33 |     result = [_item["foo"] for _item in my_list]  # RUF052: Local dummy variable `_item` is accessed
+   |                                ^^^^^
+34 |
+35 |     # Should detect used dummy variable in nested comprehension
+   |
+help: Remove leading underscores
+30 |     my_list = [{"foo": 1}, {"foo": 2}]
+31 | 
+32 |     # Should detect used dummy variable
+   -     result = [_item["foo"] for _item in my_list]  # RUF052: Local dummy variable `_item` is accessed
+33 +     result = [item["foo"] for item in my_list]  # RUF052: Local dummy variable `_item` is accessed
+34 | 
+35 |     # Should detect used dummy variable in nested comprehension
+36 |     nested = [[_item["foo"] for _item in _sublist] for _sublist in [my_list, my_list]]
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_item` is accessed
+  --> RUF052_1.py:36:33
+   |
+35 |     # Should detect used dummy variable in nested comprehension
+36 |     nested = [[_item["foo"] for _item in _sublist] for _sublist in [my_list, my_list]]
+   |                                 ^^^^^
+37 |     # RUF052: Both `_item` and `_sublist` are accessed
+   |
+help: Remove leading underscores
+33 |     result = [_item["foo"] for _item in my_list]  # RUF052: Local dummy variable `_item` is accessed
+34 | 
+35 |     # Should detect used dummy variable in nested comprehension
+   -     nested = [[_item["foo"] for _item in _sublist] for _sublist in [my_list, my_list]]
+36 +     nested = [[item["foo"] for item in _sublist] for _sublist in [my_list, my_list]]
+37 |     # RUF052: Both `_item` and `_sublist` are accessed
+38 | 
+39 |     # Should detect with conditions
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_sublist` is accessed
+  --> RUF052_1.py:36:56
+   |
+35 |     # Should detect used dummy variable in nested comprehension
+36 |     nested = [[_item["foo"] for _item in _sublist] for _sublist in [my_list, my_list]]
+   |                                                        ^^^^^^^^
+37 |     # RUF052: Both `_item` and `_sublist` are accessed
+   |
+help: Remove leading underscores
+33 |     result = [_item["foo"] for _item in my_list]  # RUF052: Local dummy variable `_item` is accessed
+34 | 
+35 |     # Should detect used dummy variable in nested comprehension
+   -     nested = [[_item["foo"] for _item in _sublist] for _sublist in [my_list, my_list]]
+36 +     nested = [[_item["foo"] for _item in sublist] for sublist in [my_list, my_list]]
+37 |     # RUF052: Both `_item` and `_sublist` are accessed
+38 | 
+39 |     # Should detect with conditions
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_item` is accessed
+  --> RUF052_1.py:40:34
+   |
+39 |     # Should detect with conditions
+40 |     filtered = [_item["foo"] for _item in my_list if _item["foo"] > 0]
+   |                                  ^^^^^
+41 |     # RUF052: Local dummy variable `_item` is accessed
+   |
+help: Remove leading underscores
+37 |     # RUF052: Both `_item` and `_sublist` are accessed
+38 | 
+39 |     # Should detect with conditions
+   -     filtered = [_item["foo"] for _item in my_list if _item["foo"] > 0]
+40 +     filtered = [item["foo"] for item in my_list if item["foo"] > 0]
+41 |     # RUF052: Local dummy variable `_item` is accessed
+42 | 
+43 | # Dict Comprehensions
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_item` is accessed
+  --> RUF052_1.py:48:48
+   |
+47 |     # Should detect used dummy variable
+48 |     result = {_item["key"]: _item["value"] for _item in my_list}
+   |                                                ^^^^^
+49 |     # RUF052: Local dummy variable `_item` is accessed
+   |
+help: Remove leading underscores
+45 |     my_list = [{"key": "a", "value": 1}, {"key": "b", "value": 2}]
+46 | 
+47 |     # Should detect used dummy variable
+   -     result = {_item["key"]: _item["value"] for _item in my_list}
+48 +     result = {item["key"]: item["value"] for item in my_list}
+49 |     # RUF052: Local dummy variable `_item` is accessed
+50 | 
+51 |     # Should detect with enumerate
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_index` is accessed
+  --> RUF052_1.py:52:43
+   |
+51 |     # Should detect with enumerate
+52 |     indexed = {_index: _item["value"] for _index, _item in enumerate(my_list)}
+   |                                           ^^^^^^
+53 |     # RUF052: Both `_index` and `_item` are accessed
+   |
+help: Remove leading underscores
+49 |     # RUF052: Local dummy variable `_item` is accessed
+50 | 
+51 |     # Should detect with enumerate
+   -     indexed = {_index: _item["value"] for _index, _item in enumerate(my_list)}
+52 +     indexed = {index: _item["value"] for index, _item in enumerate(my_list)}
+53 |     # RUF052: Both `_index` and `_item` are accessed
+54 | 
+55 |     # Should detect in nested dict comprehension
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_item` is accessed
+  --> RUF052_1.py:52:51
+   |
+51 |     # Should detect with enumerate
+52 |     indexed = {_index: _item["value"] for _index, _item in enumerate(my_list)}
+   |                                                   ^^^^^
+53 |     # RUF052: Both `_index` and `_item` are accessed
+   |
+help: Remove leading underscores
+49 |     # RUF052: Local dummy variable `_item` is accessed
+50 | 
+51 |     # Should detect with enumerate
+   -     indexed = {_index: _item["value"] for _index, _item in enumerate(my_list)}
+52 +     indexed = {_index: item["value"] for _index, item in enumerate(my_list)}
+53 |     # RUF052: Both `_index` and `_item` are accessed
+54 | 
+55 |     # Should detect in nested dict comprehension
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_inner` is accessed
+  --> RUF052_1.py:56:59
+   |
+55 |     # Should detect in nested dict comprehension
+56 |     nested = {_outer: {_inner["key"]: _inner["value"] for _inner in sublist}
+   |                                                           ^^^^^^
+57 |               for _outer, sublist in enumerate([my_list])}
+58 |     # RUF052: `_outer`, `_inner` are accessed
+   |
+help: Remove leading underscores
+53 |     # RUF052: Both `_index` and `_item` are accessed
+54 | 
+55 |     # Should detect in nested dict comprehension
+   -     nested = {_outer: {_inner["key"]: _inner["value"] for _inner in sublist}
+56 +     nested = {_outer: {inner["key"]: inner["value"] for inner in sublist}
+57 |               for _outer, sublist in enumerate([my_list])}
+58 |     # RUF052: `_outer`, `_inner` are accessed
+59 | 
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_outer` is accessed
+  --> RUF052_1.py:57:19
+   |
+55 |     # Should detect in nested dict comprehension
+56 |     nested = {_outer: {_inner["key"]: _inner["value"] for _inner in sublist}
+57 |               for _outer, sublist in enumerate([my_list])}
+   |                   ^^^^^^
+58 |     # RUF052: `_outer`, `_inner` are accessed
+   |
+help: Remove leading underscores
+53 |     # RUF052: Both `_index` and `_item` are accessed
+54 | 
+55 |     # Should detect in nested dict comprehension
+   -     nested = {_outer: {_inner["key"]: _inner["value"] for _inner in sublist}
+   -               for _outer, sublist in enumerate([my_list])}
+56 +     nested = {outer: {_inner["key"]: _inner["value"] for _inner in sublist}
+57 +               for outer, sublist in enumerate([my_list])}
+58 |     # RUF052: `_outer`, `_inner` are accessed
+59 | 
+60 | # Set Comprehensions
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_item` is accessed
+  --> RUF052_1.py:65:39
+   |
+64 |     # Should detect used dummy variable
+65 |     unique_values = {_item["foo"] for _item in my_list}
+   |                                       ^^^^^
+66 |     # RUF052: Local dummy variable `_item` is accessed
+   |
+help: Remove leading underscores
+62 |     my_list = [{"foo": 1}, {"foo": 2}, {"foo": 1}]  # Note: duplicate values
+63 | 
+64 |     # Should detect used dummy variable
+   -     unique_values = {_item["foo"] for _item in my_list}
+65 +     unique_values = {item["foo"] for item in my_list}
+66 |     # RUF052: Local dummy variable `_item` is accessed
+67 | 
+68 |     # Should detect with conditions
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_item` is accessed
+  --> RUF052_1.py:69:38
+   |
+68 |     # Should detect with conditions
+69 |     filtered_set = {_item["foo"] for _item in my_list if _item["foo"] > 0}
+   |                                      ^^^^^
+70 |     # RUF052: Local dummy variable `_item` is accessed
+   |
+help: Remove leading underscores
+66 |     # RUF052: Local dummy variable `_item` is accessed
+67 | 
+68 |     # Should detect with conditions
+   -     filtered_set = {_item["foo"] for _item in my_list if _item["foo"] > 0}
+69 +     filtered_set = {item["foo"] for item in my_list if item["foo"] > 0}
+70 |     # RUF052: Local dummy variable `_item` is accessed
+71 | 
+72 |     # Should detect with complex expression
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_item` is accessed
+  --> RUF052_1.py:73:39
+   |
+72 |     # Should detect with complex expression
+73 |     processed = {_item["foo"] * 2 for _item in my_list}
+   |                                       ^^^^^
+74 |     # RUF052: Local dummy variable `_item` is accessed
+   |
+help: Remove leading underscores
+70 |     # RUF052: Local dummy variable `_item` is accessed
+71 | 
+72 |     # Should detect with complex expression
+   -     processed = {_item["foo"] * 2 for _item in my_list}
+73 +     processed = {item["foo"] * 2 for item in my_list}
+74 |     # RUF052: Local dummy variable `_item` is accessed
+75 | 
+76 | # Generator Expressions
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_item` is accessed
+  --> RUF052_1.py:81:29
+   |
+80 |     # Should detect used dummy variable
+81 |     gen = (_item["foo"] for _item in my_list)
+   |                             ^^^^^
+82 |     # RUF052: Local dummy variable `_item` is accessed
+   |
+help: Remove leading underscores
+78 |     my_list = [{"foo": 1}, {"foo": 2}]
+79 | 
+80 |     # Should detect used dummy variable
+   -     gen = (_item["foo"] for _item in my_list)
+81 +     gen = (item["foo"] for item in my_list)
+82 |     # RUF052: Local dummy variable `_item` is accessed
+83 | 
+84 |     # Should detect when passed to function
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_item` is accessed
+  --> RUF052_1.py:85:34
+   |
+84 |     # Should detect when passed to function
+85 |     total = sum(_item["foo"] for _item in my_list)
+   |                                  ^^^^^
+86 |     # RUF052: Local dummy variable `_item` is accessed
+   |
+help: Remove leading underscores
+82 |     # RUF052: Local dummy variable `_item` is accessed
+83 | 
+84 |     # Should detect when passed to function
+   -     total = sum(_item["foo"] for _item in my_list)
+85 +     total = sum(item["foo"] for item in my_list)
+86 |     # RUF052: Local dummy variable `_item` is accessed
+87 | 
+88 |     # Should detect with multiple generators
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_x` is accessed
+  --> RUF052_1.py:89:27
+   |
+88 |     # Should detect with multiple generators
+89 |     pairs = ((_x, _y) for _x in range(3) for _y in range(3) if _x != _y)
+   |                           ^^
+90 |     # RUF052: Both `_x` and `_y` are accessed
+   |
+help: Remove leading underscores
+86 |     # RUF052: Local dummy variable `_item` is accessed
+87 | 
+88 |     # Should detect with multiple generators
+   -     pairs = ((_x, _y) for _x in range(3) for _y in range(3) if _x != _y)
+89 +     pairs = ((x, _y) for x in range(3) for _y in range(3) if x != _y)
+90 |     # RUF052: Both `_x` and `_y` are accessed
+91 | 
+92 |     # Should detect in nested generator
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_y` is accessed
+  --> RUF052_1.py:89:46
+   |
+88 |     # Should detect with multiple generators
+89 |     pairs = ((_x, _y) for _x in range(3) for _y in range(3) if _x != _y)
+   |                                              ^^
+90 |     # RUF052: Both `_x` and `_y` are accessed
+   |
+help: Remove leading underscores
+86 |     # RUF052: Local dummy variable `_item` is accessed
+87 | 
+88 |     # Should detect with multiple generators
+   -     pairs = ((_x, _y) for _x in range(3) for _y in range(3) if _x != _y)
+89 +     pairs = ((_x, y) for _x in range(3) for y in range(3) if _x != y)
+90 |     # RUF052: Both `_x` and `_y` are accessed
+91 | 
+92 |     # Should detect in nested generator
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_inner` is accessed
+  --> RUF052_1.py:93:41
+   |
+92 |     # Should detect in nested generator
+93 |     nested_gen = (sum(_inner["foo"] for _inner in sublist) for _sublist in [my_list] for sublist in _sublist)
+   |                                         ^^^^^^
+94 |     # RUF052: `_inner` and `_sublist` are accessed
+   |
+help: Remove leading underscores
+90 |     # RUF052: Both `_x` and `_y` are accessed
+91 | 
+92 |     # Should detect in nested generator
+   -     nested_gen = (sum(_inner["foo"] for _inner in sublist) for _sublist in [my_list] for sublist in _sublist)
+93 +     nested_gen = (sum(inner["foo"] for inner in sublist) for _sublist in [my_list] for sublist in _sublist)
+94 |     # RUF052: `_inner` and `_sublist` are accessed
+95 | 
+96 | # Complex Examples with Multiple Comprehension Types
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_sublist` is accessed
+  --> RUF052_1.py:93:64
+   |
+92 |     # Should detect in nested generator
+93 |     nested_gen = (sum(_inner["foo"] for _inner in sublist) for _sublist in [my_list] for sublist in _sublist)
+   |                                                                ^^^^^^^^
+94 |     # RUF052: `_inner` and `_sublist` are accessed
+   |
+help: Prefer using trailing underscores to avoid shadowing a variable
+90 |     # RUF052: Both `_x` and `_y` are accessed
+91 | 
+92 |     # Should detect in nested generator
+   -     nested_gen = (sum(_inner["foo"] for _inner in sublist) for _sublist in [my_list] for sublist in _sublist)
+93 +     nested_gen = (sum(_inner["foo"] for _inner in sublist) for sublist_ in [my_list] for sublist in sublist_)
+94 |     # RUF052: `_inner` and `_sublist` are accessed
+95 | 
+96 | # Complex Examples with Multiple Comprehension Types
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_val` is accessed
+   --> RUF052_1.py:102:30
+    |
+100 |     # Should detect in mixed comprehensions
+101 |     result = [
+102 |         {_key: [_val * 2 for _val in _record["items"]] for _key in ["doubled"]}
+    |                              ^^^^
+103 |         for _record in data
+104 |     ]
+    |
+help: Remove leading underscores
+99  | 
+100 |     # Should detect in mixed comprehensions
+101 |     result = [
+    -         {_key: [_val * 2 for _val in _record["items"]] for _key in ["doubled"]}
+102 +         {_key: [val * 2 for val in _record["items"]] for _key in ["doubled"]}
+103 |         for _record in data
+104 |     ]
+105 |     # RUF052: `_key`, `_val`, and `_record` are all accessed
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_key` is accessed
+   --> RUF052_1.py:102:60
+    |
+100 |     # Should detect in mixed comprehensions
+101 |     result = [
+102 |         {_key: [_val * 2 for _val in _record["items"]] for _key in ["doubled"]}
+    |                                                            ^^^^
+103 |         for _record in data
+104 |     ]
+    |
+help: Remove leading underscores
+99  | 
+100 |     # Should detect in mixed comprehensions
+101 |     result = [
+    -         {_key: [_val * 2 for _val in _record["items"]] for _key in ["doubled"]}
+102 +         {key: [_val * 2 for _val in _record["items"]] for key in ["doubled"]}
+103 |         for _record in data
+104 |     ]
+105 |     # RUF052: `_key`, `_val`, and `_record` are all accessed
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_record` is accessed
+   --> RUF052_1.py:103:13
+    |
+101 |     result = [
+102 |         {_key: [_val * 2 for _val in _record["items"]] for _key in ["doubled"]}
+103 |         for _record in data
+    |             ^^^^^^^
+104 |     ]
+105 |     # RUF052: `_key`, `_val`, and `_record` are all accessed
+    |
+help: Remove leading underscores
+99  | 
+100 |     # Should detect in mixed comprehensions
+101 |     result = [
+    -         {_key: [_val * 2 for _val in _record["items"]] for _key in ["doubled"]}
+    -         for _record in data
+102 +         {_key: [_val * 2 for _val in record["items"]] for _key in ["doubled"]}
+103 +         for record in data
+104 |     ]
+105 |     # RUF052: `_key`, `_val`, and `_record` are all accessed
+106 | 
+note: This is an unsafe fix and may change runtime behavior
+
+RUF052 [*] Local dummy variable `_item` is accessed
+   --> RUF052_1.py:108:43
+    |
+107 |     # Should detect in generator passed to list constructor
+108 |     gen_list = list(_item["items"][0] for _item in data)
+    |                                           ^^^^^
+109 |     # RUF052: Local dummy variable `_item` is accessed
+    |
+help: Remove leading underscores
+105 |     # RUF052: `_key`, `_val`, and `_record` are all accessed
+106 | 
+107 |     # Should detect in generator passed to list constructor
+    -     gen_list = list(_item["items"][0] for _item in data)
+108 +     gen_list = list(item["items"][0] for item in data)
+109 |     # RUF052: Local dummy variable `_item` is accessed
+note: This is an unsafe fix and may change runtime behavior

crates/ruff_linter/src/rules/ruff/snapshots/ruff_linter__rules__ruff__tests__custom_dummy_var_regexp_preset__RUF052_RUF052_0.py_1.snap

@@ -2,7 +2,7 @@
 source: crates/ruff_linter/src/rules/ruff/mod.rs
 ---
 RUF052 [*] Local dummy variable `_var` is accessed
-  --> RUF052.py:92:9
+  --> RUF052_0.py:92:9
    |
 90 | class Class_:
 91 |     def fun(self):
@@ -24,7 +24,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_list` is accessed
-   --> RUF052.py:99:5
+   --> RUF052_0.py:99:5
     |
  98 | def fun():
  99 |     _list = "built-in" # [RUF052]
@@ -45,7 +45,7 @@ help: Prefer using trailing underscores to avoid shadowing a built-in
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_x` is accessed
-   --> RUF052.py:106:5
+   --> RUF052_0.py:106:5
     |
 104 | def fun():
 105 |     global x
@@ -67,7 +67,7 @@ help: Prefer using trailing underscores to avoid shadowing a variable
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_x` is accessed
-   --> RUF052.py:113:5
+   --> RUF052_0.py:113:5
     |
 111 |   def bar():
 112 |     nonlocal x
@@ -90,7 +90,7 @@ help: Prefer using trailing underscores to avoid shadowing a variable
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_x` is accessed
-   --> RUF052.py:120:5
+   --> RUF052_0.py:120:5
     |
 118 | def fun():
 119 |     x = "local"
@@ -112,7 +112,7 @@ help: Prefer using trailing underscores to avoid shadowing a variable
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 Local dummy variable `_GLOBAL_1` is accessed
-   --> RUF052.py:128:5
+   --> RUF052_0.py:128:5
     |
 127 | def unfixables():
 128 |     _GLOBAL_1 = "foo"
@@ -123,7 +123,7 @@ RUF052 Local dummy variable `_GLOBAL_1` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_local` is accessed
-   --> RUF052.py:136:5
+   --> RUF052_0.py:136:5
     |
 135 |     # unfixable because the rename would shadow a local variable
 136 |     _local = "local3"  # [RUF052]
@@ -133,7 +133,7 @@ RUF052 Local dummy variable `_local` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_GLOBAL_1` is accessed
-   --> RUF052.py:140:9
+   --> RUF052_0.py:140:9
     |
 139 |     def nested():
 140 |         _GLOBAL_1 = "foo"
@@ -144,7 +144,7 @@ RUF052 Local dummy variable `_GLOBAL_1` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_local` is accessed
-   --> RUF052.py:145:9
+   --> RUF052_0.py:145:9
     |
 144 |         # unfixable because the rename would shadow a variable from the outer function
 145 |         _local = "local4"
@@ -154,7 +154,7 @@ RUF052 Local dummy variable `_local` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 [*] Local dummy variable `_P` is accessed
-   --> RUF052.py:153:5
+   --> RUF052_0.py:153:5
     |
 151 |     from collections import namedtuple
 152 |
@@ -184,7 +184,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_T` is accessed
-   --> RUF052.py:154:5
+   --> RUF052_0.py:154:5
     |
 153 |     _P = ParamSpec("_P")
 154 |     _T = TypeVar(name="_T", covariant=True, bound=int|str)
@@ -213,7 +213,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_NT` is accessed
-   --> RUF052.py:155:5
+   --> RUF052_0.py:155:5
     |
 153 |     _P = ParamSpec("_P")
 154 |     _T = TypeVar(name="_T", covariant=True, bound=int|str)
@@ -242,7 +242,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_E` is accessed
-   --> RUF052.py:156:5
+   --> RUF052_0.py:156:5
     |
 154 |     _T = TypeVar(name="_T", covariant=True, bound=int|str)
 155 |     _NT = NamedTuple("_NT", [("foo", int)])
@@ -270,7 +270,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_NT2` is accessed
-   --> RUF052.py:157:5
+   --> RUF052_0.py:157:5
     |
 155 |     _NT = NamedTuple("_NT", [("foo", int)])
 156 |     _E = Enum("_E", ["a", "b", "c"])
@@ -297,7 +297,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_NT3` is accessed
-   --> RUF052.py:158:5
+   --> RUF052_0.py:158:5
     |
 156 |     _E = Enum("_E", ["a", "b", "c"])
 157 |     _NT2 = namedtuple("_NT2", ['x', 'y', 'z'])
@@ -323,7 +323,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_DynamicClass` is accessed
-   --> RUF052.py:159:5
+   --> RUF052_0.py:159:5
     |
 157 |     _NT2 = namedtuple("_NT2", ['x', 'y', 'z'])
 158 |     _NT3 = namedtuple(typename="_NT3", field_names=['x', 'y', 'z'])
@@ -347,7 +347,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_NotADynamicClass` is accessed
-   --> RUF052.py:160:5
+   --> RUF052_0.py:160:5
     |
 158 |     _NT3 = namedtuple(typename="_NT3", field_names=['x', 'y', 'z'])
 159 |     _DynamicClass = type("_DynamicClass", (), {})
@@ -371,7 +371,7 @@ help: Remove leading underscores
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 [*] Local dummy variable `_dummy_var` is accessed
-   --> RUF052.py:182:5
+   --> RUF052_0.py:182:5
     |
 181 | def foo():
 182 |     _dummy_var = 42
@@ -396,7 +396,7 @@ help: Prefer using trailing underscores to avoid shadowing a variable
 note: This is an unsafe fix and may change runtime behavior
 
 RUF052 Local dummy variable `_dummy_var` is accessed
-   --> RUF052.py:192:5
+   --> RUF052_0.py:192:5
     |
 190 |     # Unfixable because both possible candidates for the new name are shadowed
 191 |     # in the scope of one of the references to the variable

crates/ruff_linter/src/rules/ruff/snapshots/ruff_linter__rules__ruff__tests__custom_dummy_var_regexp_preset__RUF052_RUF052_0.py_2.snap

@@ -2,7 +2,7 @@
 source: crates/ruff_linter/src/rules/ruff/mod.rs
 ---
 RUF052 Local dummy variable `_var` is accessed
-  --> RUF052.py:92:9
+  --> RUF052_0.py:92:9
    |
 90 | class Class_:
 91 |     def fun(self):
@@ -13,7 +13,7 @@ RUF052 Local dummy variable `_var` is accessed
 help: Remove leading underscores
 
 RUF052 Local dummy variable `_list` is accessed
-   --> RUF052.py:99:5
+   --> RUF052_0.py:99:5
     |
  98 | def fun():
  99 |     _list = "built-in" # [RUF052]
@@ -23,7 +23,7 @@ RUF052 Local dummy variable `_list` is accessed
 help: Prefer using trailing underscores to avoid shadowing a built-in
 
 RUF052 Local dummy variable `_x` is accessed
-   --> RUF052.py:106:5
+   --> RUF052_0.py:106:5
     |
 104 | def fun():
 105 |     global x
@@ -34,7 +34,7 @@ RUF052 Local dummy variable `_x` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `x` is accessed
-   --> RUF052.py:110:3
+   --> RUF052_0.py:110:3
     |
 109 | def foo():
 110 |   x = "outer"
@@ -44,7 +44,7 @@ RUF052 Local dummy variable `x` is accessed
     |
 
 RUF052 Local dummy variable `_x` is accessed
-   --> RUF052.py:113:5
+   --> RUF052_0.py:113:5
     |
 111 |   def bar():
 112 |     nonlocal x
@@ -56,7 +56,7 @@ RUF052 Local dummy variable `_x` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_x` is accessed
-   --> RUF052.py:120:5
+   --> RUF052_0.py:120:5
     |
 118 | def fun():
 119 |     x = "local"
@@ -67,7 +67,7 @@ RUF052 Local dummy variable `_x` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_GLOBAL_1` is accessed
-   --> RUF052.py:128:5
+   --> RUF052_0.py:128:5
     |
 127 | def unfixables():
 128 |     _GLOBAL_1 = "foo"
@@ -78,7 +78,7 @@ RUF052 Local dummy variable `_GLOBAL_1` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_local` is accessed
-   --> RUF052.py:136:5
+   --> RUF052_0.py:136:5
     |
 135 |     # unfixable because the rename would shadow a local variable
 136 |     _local = "local3"  # [RUF052]
@@ -88,7 +88,7 @@ RUF052 Local dummy variable `_local` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_GLOBAL_1` is accessed
-   --> RUF052.py:140:9
+   --> RUF052_0.py:140:9
     |
 139 |     def nested():
 140 |         _GLOBAL_1 = "foo"
@@ -99,7 +99,7 @@ RUF052 Local dummy variable `_GLOBAL_1` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_local` is accessed
-   --> RUF052.py:145:9
+   --> RUF052_0.py:145:9
     |
 144 |         # unfixable because the rename would shadow a variable from the outer function
 145 |         _local = "local4"
@@ -109,7 +109,7 @@ RUF052 Local dummy variable `_local` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_P` is accessed
-   --> RUF052.py:153:5
+   --> RUF052_0.py:153:5
     |
 151 |     from collections import namedtuple
 152 |
@@ -121,7 +121,7 @@ RUF052 Local dummy variable `_P` is accessed
 help: Remove leading underscores
 
 RUF052 Local dummy variable `_T` is accessed
-   --> RUF052.py:154:5
+   --> RUF052_0.py:154:5
     |
 153 |     _P = ParamSpec("_P")
 154 |     _T = TypeVar(name="_T", covariant=True, bound=int|str)
@@ -132,7 +132,7 @@ RUF052 Local dummy variable `_T` is accessed
 help: Remove leading underscores
 
 RUF052 Local dummy variable `_NT` is accessed
-   --> RUF052.py:155:5
+   --> RUF052_0.py:155:5
     |
 153 |     _P = ParamSpec("_P")
 154 |     _T = TypeVar(name="_T", covariant=True, bound=int|str)
@@ -144,7 +144,7 @@ RUF052 Local dummy variable `_NT` is accessed
 help: Remove leading underscores
 
 RUF052 Local dummy variable `_E` is accessed
-   --> RUF052.py:156:5
+   --> RUF052_0.py:156:5
     |
 154 |     _T = TypeVar(name="_T", covariant=True, bound=int|str)
 155 |     _NT = NamedTuple("_NT", [("foo", int)])
@@ -156,7 +156,7 @@ RUF052 Local dummy variable `_E` is accessed
 help: Remove leading underscores
 
 RUF052 Local dummy variable `_NT2` is accessed
-   --> RUF052.py:157:5
+   --> RUF052_0.py:157:5
     |
 155 |     _NT = NamedTuple("_NT", [("foo", int)])
 156 |     _E = Enum("_E", ["a", "b", "c"])
@@ -168,7 +168,7 @@ RUF052 Local dummy variable `_NT2` is accessed
 help: Remove leading underscores
 
 RUF052 Local dummy variable `_NT3` is accessed
-   --> RUF052.py:158:5
+   --> RUF052_0.py:158:5
     |
 156 |     _E = Enum("_E", ["a", "b", "c"])
 157 |     _NT2 = namedtuple("_NT2", ['x', 'y', 'z'])
@@ -180,7 +180,7 @@ RUF052 Local dummy variable `_NT3` is accessed
 help: Remove leading underscores
 
 RUF052 Local dummy variable `_DynamicClass` is accessed
-   --> RUF052.py:159:5
+   --> RUF052_0.py:159:5
     |
 157 |     _NT2 = namedtuple("_NT2", ['x', 'y', 'z'])
 158 |     _NT3 = namedtuple(typename="_NT3", field_names=['x', 'y', 'z'])
@@ -191,7 +191,7 @@ RUF052 Local dummy variable `_DynamicClass` is accessed
 help: Remove leading underscores
 
 RUF052 Local dummy variable `_NotADynamicClass` is accessed
-   --> RUF052.py:160:5
+   --> RUF052_0.py:160:5
     |
 158 |     _NT3 = namedtuple(typename="_NT3", field_names=['x', 'y', 'z'])
 159 |     _DynamicClass = type("_DynamicClass", (), {})
@@ -202,8 +202,18 @@ RUF052 Local dummy variable `_NotADynamicClass` is accessed
     |
 help: Remove leading underscores
 
+RUF052 Local dummy variable `other` is accessed
+   --> RUF052_0.py:177:13
+    |
+175 |             return
+176 |         _seen.add(self)
+177 |         for other in self.connected:
+    |             ^^^^^
+178 |             other.recurse(_seen=_seen)
+    |
+
 RUF052 Local dummy variable `_dummy_var` is accessed
-   --> RUF052.py:182:5
+   --> RUF052_0.py:182:5
     |
 181 | def foo():
 182 |     _dummy_var = 42
@@ -214,7 +224,7 @@ RUF052 Local dummy variable `_dummy_var` is accessed
 help: Prefer using trailing underscores to avoid shadowing a variable
 
 RUF052 Local dummy variable `_dummy_var` is accessed
-   --> RUF052.py:192:5
+   --> RUF052_0.py:192:5
     |
 190 |     # Unfixable because both possible candidates for the new name are shadowed
 191 |     # in the scope of one of the references to the variable

crates/ruff_python_ast/src/nodes.rs

@@ -773,10 +773,14 @@ pub trait StringFlags: Copy {
     }
 
     /// The total length of the string's closer.
-    /// This is always equal to `self.quote_len()`,
-    /// but is provided here for symmetry with the `opener_len()` method.
+    /// This is always equal to `self.quote_len()`, except when the string is unclosed,
+    /// in which case the length is zero.
     fn closer_len(self) -> TextSize {
-        self.quote_len()
+        if self.is_unclosed() {
+            TextSize::default()
+        } else {
+            self.quote_len()
+        }
     }
 
     fn as_any_string_flags(self) -> AnyStringFlags {

crates/ruff_python_parser/resources/inline/err/ipython_help_escape_command_error_recovery_1.py

@@ -0,0 +1,3 @@
+# parse_options: {"mode": "ipython"}
+with (a, ?b)
+?

crates/ruff_python_parser/resources/inline/err/ipython_help_escape_command_error_recovery_2.py

@@ -0,0 +1,3 @@
+# parse_options: {"mode": "ipython"}
+with (a, ?b
+?

crates/ruff_python_parser/resources/inline/err/ipython_help_escape_command_error_recovery_3.py

@@ -0,0 +1,4 @@
+# parse_options: {"mode": "ipython"}
+with a, ?b
+?
+x = 1

crates/ruff_python_parser/src/parser/mod.rs

@@ -1115,7 +1115,27 @@ impl RecoveryContextKind {
                     TokenKind::Colon => Some(ListTerminatorKind::ErrorRecovery),
                     _ => None,
                 },
-                WithItemKind::Unparenthesized | WithItemKind::ParenthesizedExpression => p
+                // test_err ipython_help_escape_command_error_recovery_1
+                // # parse_options: {"mode": "ipython"}
+                // with (a, ?b)
+                // ?
+
+                // test_err ipython_help_escape_command_error_recovery_2
+                // # parse_options: {"mode": "ipython"}
+                // with (a, ?b
+                // ?
+
+                // test_err ipython_help_escape_command_error_recovery_3
+                // # parse_options: {"mode": "ipython"}
+                // with a, ?b
+                // ?
+                // x = 1
+                WithItemKind::Unparenthesized => matches!(
+                    p.current_token_kind(),
+                    TokenKind::Colon | TokenKind::Newline
+                )
+                .then_some(ListTerminatorKind::Regular),
+                WithItemKind::ParenthesizedExpression => p
                     .at(TokenKind::Colon)
                     .then_some(ListTerminatorKind::Regular),
             },

crates/ruff_python_parser/tests/snapshots/invalid_syntax@ipython_help_escape_command_error_recovery_1.py.snap

@@ -0,0 +1,84 @@
+---
+source: crates/ruff_python_parser/tests/fixtures.rs
+input_file: crates/ruff_python_parser/resources/inline/err/ipython_help_escape_command_error_recovery_1.py
+---
+## AST
+
+```
+Module(
+    ModModule {
+        node_index: NodeIndex(None),
+        range: 0..52,
+        body: [
+            With(
+                StmtWith {
+                    node_index: NodeIndex(None),
+                    range: 37..49,
+                    is_async: false,
+                    items: [
+                        WithItem {
+                            range: 43..44,
+                            node_index: NodeIndex(None),
+                            context_expr: Name(
+                                ExprName {
+                                    node_index: NodeIndex(None),
+                                    range: 43..44,
+                                    id: Name("a"),
+                                    ctx: Load,
+                                },
+                            ),
+                            optional_vars: None,
+                        },
+                        WithItem {
+                            range: 47..48,
+                            node_index: NodeIndex(None),
+                            context_expr: Name(
+                                ExprName {
+                                    node_index: NodeIndex(None),
+                                    range: 47..48,
+                                    id: Name("b"),
+                                    ctx: Load,
+                                },
+                            ),
+                            optional_vars: None,
+                        },
+                    ],
+                    body: [],
+                },
+            ),
+            IpyEscapeCommand(
+                StmtIpyEscapeCommand {
+                    node_index: NodeIndex(None),
+                    range: 50..51,
+                    kind: Help,
+                    value: "",
+                },
+            ),
+        ],
+    },
+)
+```
+## Errors
+
+  |
+1 | # parse_options: {"mode": "ipython"}
+2 | with (a, ?b)
+  |          ^ Syntax Error: Expected `,`, found `?`
+3 | ?
+  |
+
+
+  |
+1 | # parse_options: {"mode": "ipython"}
+2 | with (a, ?b)
+  |             ^ Syntax Error: Expected `:`, found newline
+3 | ?
+  |
+
+
+  |
+1 | # parse_options: {"mode": "ipython"}
+2 | with (a, ?b)
+3 | ?
+  | ^ Syntax Error: Expected an indented block after `with` statement
+  |

crates/ruff_python_parser/tests/snapshots/invalid_syntax@ipython_help_escape_command_error_recovery_2.py.snap

@@ -0,0 +1,80 @@
+---
+source: crates/ruff_python_parser/tests/fixtures.rs
+input_file: crates/ruff_python_parser/resources/inline/err/ipython_help_escape_command_error_recovery_2.py
+---
+## AST
+
+```
+Module(
+    ModModule {
+        node_index: NodeIndex(None),
+        range: 0..51,
+        body: [
+            With(
+                StmtWith {
+                    node_index: NodeIndex(None),
+                    range: 37..51,
+                    is_async: false,
+                    items: [
+                        WithItem {
+                            range: 42..51,
+                            node_index: NodeIndex(None),
+                            context_expr: Tuple(
+                                ExprTuple {
+                                    node_index: NodeIndex(None),
+                                    range: 42..51,
+                                    elts: [
+                                        Name(
+                                            ExprName {
+                                                node_index: NodeIndex(None),
+                                                range: 43..44,
+                                                id: Name("a"),
+                                                ctx: Load,
+                                            },
+                                        ),
+                                        Name(
+                                            ExprName {
+                                                node_index: NodeIndex(None),
+                                                range: 47..48,
+                                                id: Name("b"),
+                                                ctx: Load,
+                                            },
+                                        ),
+                                    ],
+                                    ctx: Load,
+                                    parenthesized: true,
+                                },
+                            ),
+                            optional_vars: None,
+                        },
+                    ],
+                    body: [],
+                },
+            ),
+        ],
+    },
+)
+```
+## Errors
+
+  |
+1 | # parse_options: {"mode": "ipython"}
+2 | with (a, ?b
+  |          ^ Syntax Error: Expected an expression or a ')'
+3 | ?
+  |
+
+
+  |
+1 | # parse_options: {"mode": "ipython"}
+2 | with (a, ?b
+3 | ?
+  | ^ Syntax Error: Expected `,`, found `?`
+  |
+
+
+  |
+2 | with (a, ?b
+3 | ?
+  |  ^ Syntax Error: unexpected EOF while parsing
+  |

crates/ruff_python_parser/tests/snapshots/invalid_syntax@ipython_help_escape_command_error_recovery_3.py.snap

@@ -0,0 +1,112 @@
+---
+source: crates/ruff_python_parser/tests/fixtures.rs
+input_file: crates/ruff_python_parser/resources/inline/err/ipython_help_escape_command_error_recovery_3.py
+---
+## AST
+
+```
+Module(
+    ModModule {
+        node_index: NodeIndex(None),
+        range: 0..56,
+        body: [
+            With(
+                StmtWith {
+                    node_index: NodeIndex(None),
+                    range: 37..47,
+                    is_async: false,
+                    items: [
+                        WithItem {
+                            range: 42..43,
+                            node_index: NodeIndex(None),
+                            context_expr: Name(
+                                ExprName {
+                                    node_index: NodeIndex(None),
+                                    range: 42..43,
+                                    id: Name("a"),
+                                    ctx: Load,
+                                },
+                            ),
+                            optional_vars: None,
+                        },
+                        WithItem {
+                            range: 46..47,
+                            node_index: NodeIndex(None),
+                            context_expr: Name(
+                                ExprName {
+                                    node_index: NodeIndex(None),
+                                    range: 46..47,
+                                    id: Name("b"),
+                                    ctx: Load,
+                                },
+                            ),
+                            optional_vars: None,
+                        },
+                    ],
+                    body: [],
+                },
+            ),
+            IpyEscapeCommand(
+                StmtIpyEscapeCommand {
+                    node_index: NodeIndex(None),
+                    range: 48..49,
+                    kind: Help,
+                    value: "",
+                },
+            ),
+            Assign(
+                StmtAssign {
+                    node_index: NodeIndex(None),
+                    range: 50..55,
+                    targets: [
+                        Name(
+                            ExprName {
+                                node_index: NodeIndex(None),
+                                range: 50..51,
+                                id: Name("x"),
+                                ctx: Store,
+                            },
+                        ),
+                    ],
+                    value: NumberLiteral(
+                        ExprNumberLiteral {
+                            node_index: NodeIndex(None),
+                            range: 54..55,
+                            value: Int(
+                                1,
+                            ),
+                        },
+                    ),
+                },
+            ),
+        ],
+    },
+)
+```
+## Errors
+
+  |
+1 | # parse_options: {"mode": "ipython"}
+2 | with a, ?b
+  |         ^ Syntax Error: Expected `,`, found `?`
+3 | ?
+4 | x = 1
+  |
+
+
+  |
+1 | # parse_options: {"mode": "ipython"}
+2 | with a, ?b
+  |           ^ Syntax Error: Expected `:`, found newline
+3 | ?
+4 | x = 1
+  |
+
+
+  |
+1 | # parse_options: {"mode": "ipython"}
+2 | with a, ?b
+3 | ?
+  | ^ Syntax Error: Expected an indented block after `with` statement
+4 | x = 1
+  |

crates/ruff_server/src/lint.rs

@@ -283,24 +283,27 @@ fn to_lsp_diagnostic(
         range = diagnostic_range.to_range(source_kind.source_code(), index, encoding);
     }
 
-    let (severity, tags, code) = if let Some(code) = code {
-        let code = code.to_string();
-        (
-            Some(severity(&code)),
-            tags(diagnostic),
-            Some(lsp_types::NumberOrString::String(code)),
-        )
+    let (severity, code) = if let Some(code) = code {
+        (severity(code), code.to_string())
     } else {
-        (None, None, None)
+        (
+            match diagnostic.severity() {
+                ruff_db::diagnostic::Severity::Info => lsp_types::DiagnosticSeverity::INFORMATION,
+                ruff_db::diagnostic::Severity::Warning => lsp_types::DiagnosticSeverity::WARNING,
+                ruff_db::diagnostic::Severity::Error => lsp_types::DiagnosticSeverity::ERROR,
+                ruff_db::diagnostic::Severity::Fatal => lsp_types::DiagnosticSeverity::ERROR,
+            },
+            diagnostic.id().to_string(),
+        )
     };
 
     (
         cell,
         lsp_types::Diagnostic {
             range,
-            severity,
-            tags,
-            code,
+            severity: Some(severity),
+            tags: tags(diagnostic),
+            code: Some(lsp_types::NumberOrString::String(code)),
             code_description: diagnostic.documentation_url().and_then(|url| {
                 Some(lsp_types::CodeDescription {
                     href: lsp_types::Url::parse(url).ok()?,

crates/ruff_text_size/src/size.rs

@@ -106,6 +106,25 @@ impl TextSize {
     pub fn checked_sub(self, rhs: TextSize) -> Option<TextSize> {
         self.raw.checked_sub(rhs.raw).map(|raw| TextSize { raw })
     }
+
+    /// Saturating addition. Returns maximum `TextSize` if overflow occurred.
+    #[inline]
+    #[must_use]
+    pub fn saturating_add(self, rhs: TextSize) -> TextSize {
+        TextSize {
+            raw: self.raw.saturating_add(rhs.raw),
+        }
+    }
+
+    /// Saturating subtraction. Returns minimum `TextSize` if overflow
+    /// occurred.
+    #[inline]
+    #[must_use]
+    pub fn saturating_sub(self, rhs: TextSize) -> TextSize {
+        TextSize {
+            raw: self.raw.saturating_sub(rhs.raw),
+        }
+    }
 }
 
 impl From<u32> for TextSize {

crates/ruff_wasm/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff_wasm"
-version = "0.14.5"
+version = "0.14.6"
 publish = false
 authors = { workspace = true }
 edition = { workspace = true }

crates/ty/docs/rules.md

@@ -39,7 +39,7 @@ def test(): -> "int":
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20call-non-callable" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L121" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L126" target="_blank">View source</a>
 </small>
 
 
@@ -63,7 +63,7 @@ Calling a non-callable object will raise a `TypeError` at runtime.
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20conflicting-argument-forms" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L165" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L170" target="_blank">View source</a>
 </small>
 
 
@@ -95,7 +95,7 @@ f(int)  # error
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20conflicting-declarations" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L191" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L196" target="_blank">View source</a>
 </small>
 
 
@@ -126,7 +126,7 @@ a = 1
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20conflicting-metaclass" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L216" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L221" target="_blank">View source</a>
 </small>
 
 
@@ -158,7 +158,7 @@ class C(A, B): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20cyclic-class-definition" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L242" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L247" target="_blank">View source</a>
 </small>
 
 
@@ -190,7 +190,7 @@ class B(A): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20duplicate-base" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L307" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L312" target="_blank">View source</a>
 </small>
 
 
@@ -217,7 +217,7 @@ class B(A, A): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.12">0.0.1-alpha.12</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20duplicate-kw-only" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L328" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L333" target="_blank">View source</a>
 </small>
 
 
@@ -329,7 +329,7 @@ def test(): -> "Literal[5]":
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20inconsistent-mro" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L532" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L537" target="_blank">View source</a>
 </small>
 
 
@@ -359,7 +359,7 @@ class C(A, B): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20index-out-of-bounds" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L556" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L561" target="_blank">View source</a>
 </small>
 
 
@@ -385,7 +385,7 @@ t[3]  # IndexError: tuple index out of range
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.12">0.0.1-alpha.12</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20instance-layout-conflict" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L360" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L365" target="_blank">View source</a>
 </small>
 
 
@@ -474,7 +474,7 @@ an atypical memory layout.
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-argument-type" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L610" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L615" target="_blank">View source</a>
 </small>
 
 
@@ -501,7 +501,7 @@ func("foo")  # error: [invalid-argument-type]
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-assignment" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L650" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L655" target="_blank">View source</a>
 </small>
 
 
@@ -529,7 +529,7 @@ a: int = ''
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-attribute-access" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1809" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1814" target="_blank">View source</a>
 </small>
 
 
@@ -563,7 +563,7 @@ C.instance_var = 3  # error: Cannot assign to instance variable
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.19">0.0.1-alpha.19</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-await" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L672" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L677" target="_blank">View source</a>
 </small>
 
 
@@ -599,7 +599,7 @@ asyncio.run(main())
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-base" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L702" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L707" target="_blank">View source</a>
 </small>
 
 
@@ -623,7 +623,7 @@ class A(42): ...  # error: [invalid-base]
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-context-manager" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L753" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L758" target="_blank">View source</a>
 </small>
 
 
@@ -650,7 +650,7 @@ with 1:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-declaration" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L774" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L779" target="_blank">View source</a>
 </small>
 
 
@@ -679,7 +679,7 @@ a: str
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-exception-caught" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L797" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L802" target="_blank">View source</a>
 </small>
 
 
@@ -723,7 +723,7 @@ except ZeroDivisionError:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-generic-class" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L833" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L838" target="_blank">View source</a>
 </small>
 
 
@@ -756,7 +756,7 @@ class C[U](Generic[T]): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.17">0.0.1-alpha.17</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-key" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L577" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L582" target="_blank">View source</a>
 </small>
 
 
@@ -795,7 +795,7 @@ carol = Person(name="Carol", age=25)  # typo!
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-legacy-type-variable" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L859" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L864" target="_blank">View source</a>
 </small>
 
 
@@ -830,7 +830,7 @@ def f(t: TypeVar("U")): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-metaclass" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L956" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L961" target="_blank">View source</a>
 </small>
 
 
@@ -858,13 +858,99 @@ class B(metaclass=f): ...
 
 - [Python documentation: Metaclasses](https://docs.python.org/3/reference/datamodel.html#metaclasses)
 
+## `invalid-method-override`
+
+<small>
+Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
+Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.20">0.0.1-alpha.20</a> ·
+<a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-method-override" target="_blank">Related issues</a> ·
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1942" target="_blank">View source</a>
+</small>
+
+
+**What it does**
+
+Detects method overrides that violate the [Liskov Substitution Principle] ("LSP").
+
+The LSP states that an instance of a subtype should be substitutable for an instance of its supertype.
+Applied to Python, this means:
+1. All argument combinations a superclass method accepts
+   must also be accepted by an overriding subclass method.
+2. The return type of an overriding subclass method must be a subtype
+   of the return type of the superclass method.
+
+**Why is this bad?**
+
+Violating the Liskov Substitution Principle will lead to many of ty's assumptions and
+inferences being incorrect, which will mean that it will fail to catch many possible
+type errors in your code.
+
+**Example**
+
+```python
+class Super:
+    def method(self, x) -> int:
+        return 42
+
+class Sub(Super):
+    # Liskov violation: `str` is not a subtype of `int`,
+    # but the supertype method promises to return an `int`.
+    def method(self, x) -> str:  # error: [invalid-override]
+        return "foo"
+
+def accepts_super(s: Super) -> int:
+    return s.method(x=42)
+
+accepts_super(Sub())  # The result of this call is a string, but ty will infer
+                      # it to be an `int` due to the violation of the Liskov Substitution Principle.
+
+class Sub2(Super):
+    # Liskov violation: the superclass method can be called with a `x=`
+    # keyword argument, but the subclass method does not accept it.
+    def method(self, y) -> int:  # error: [invalid-override]
+       return 42
+
+accepts_super(Sub2())  # TypeError at runtime: method() got an unexpected keyword argument 'x'
+                       # ty cannot catch this error due to the violation of the Liskov Substitution Principle.
+```
+
+**Common issues**
+
+
+**Why does ty complain about my `__eq__` method?**
+
+
+`__eq__` and `__ne__` methods in Python are generally expected to accept arbitrary
+objects as their second argument, for example:
+
+```python
+class A:
+    x: int
+
+    def __eq__(self, other: object) -> bool:
+        # gracefully handle an object of an unexpected type
+        # without raising an exception
+        if not isinstance(other, A):
+            return False
+        return self.x == other.x
+```
+
+If `A.__eq__` here were annotated as only accepting `A` instances for its second argument,
+it would imply that you wouldn't be able to use `==` between instances of `A` and
+instances of unrelated classes without an exception possibly being raised. While some
+classes in Python do indeed behave this way, the strongly held convention is that it should
+be avoided wherever possible. As part of this check, therefore, ty enforces that `__eq__`
+and `__ne__` methods accept `object` as their second argument.
+
+[Liskov Substitution Principle]: https://en.wikipedia.org/wiki/Liskov_substitution_principle
+
 ## `invalid-named-tuple`
 
 <small>
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.19">0.0.1-alpha.19</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-named-tuple" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L506" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L511" target="_blank">View source</a>
 </small>
 
 
@@ -896,7 +982,7 @@ TypeError: can only inherit from a NamedTuple type and Generic
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Preview (since <a href="https://github.com/astral-sh/ty/releases/tag/1.0.0">1.0.0</a>) ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-newtype" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L932" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L937" target="_blank">View source</a>
 </small>
 
 
@@ -926,7 +1012,7 @@ Baz = NewType("Baz", int | str)  # error: invalid base for `typing.NewType`
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-overload" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L983" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L988" target="_blank">View source</a>
 </small>
 
 
@@ -976,7 +1062,7 @@ def foo(x: int) -> int: ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-parameter-default" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1082" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1087" target="_blank">View source</a>
 </small>
 
 
@@ -1002,7 +1088,7 @@ def f(a: int = ''): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-paramspec" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L887" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L892" target="_blank">View source</a>
 </small>
 
 
@@ -1033,7 +1119,7 @@ P2 = ParamSpec("S2")  # error: ParamSpec name must match the variable it's assig
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-protocol" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L442" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L447" target="_blank">View source</a>
 </small>
 
 
@@ -1067,7 +1153,7 @@ TypeError: Protocols can only inherit from other protocols, got <class 'int'>
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-raise" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1102" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1107" target="_blank">View source</a>
 </small>
 
 
@@ -1116,7 +1202,7 @@ def g():
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-return-type" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L631" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L636" target="_blank">View source</a>
 </small>
 
 
@@ -1141,7 +1227,7 @@ def func() -> int:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-super-argument" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1145" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1150" target="_blank">View source</a>
 </small>
 
 
@@ -1199,7 +1285,7 @@ TODO #14889
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.6">0.0.1-alpha.6</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-alias-type" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L911" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L916" target="_blank">View source</a>
 </small>
 
 
@@ -1226,7 +1312,7 @@ NewAlias = TypeAliasType(get_name(), int)        # error: TypeAliasType name mus
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-checking-constant" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1184" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1189" target="_blank">View source</a>
 </small>
 
 
@@ -1256,7 +1342,7 @@ TYPE_CHECKING = ''
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-form" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1208" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1213" target="_blank">View source</a>
 </small>
 
 
@@ -1286,7 +1372,7 @@ b: Annotated[int]  # `Annotated` expects at least two arguments
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.11">0.0.1-alpha.11</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-guard-call" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1260" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1265" target="_blank">View source</a>
 </small>
 
 
@@ -1320,7 +1406,7 @@ f(10)  # Error
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.11">0.0.1-alpha.11</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-guard-definition" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1232" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1237" target="_blank">View source</a>
 </small>
 
 
@@ -1354,7 +1440,7 @@ class C:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-variable-constraints" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1288" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1293" target="_blank">View source</a>
 </small>
 
 
@@ -1389,7 +1475,7 @@ T = TypeVar('T', bound=str)  # valid bound TypeVar
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20missing-argument" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1317" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1322" target="_blank">View source</a>
 </small>
 
 
@@ -1414,7 +1500,7 @@ func()  # TypeError: func() missing 1 required positional argument: 'x'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.20">0.0.1-alpha.20</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20missing-typed-dict-key" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1910" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1915" target="_blank">View source</a>
 </small>
 
 
@@ -1447,7 +1533,7 @@ alice["age"]  # KeyError
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20no-matching-overload" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1336" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1341" target="_blank">View source</a>
 </small>
 
 
@@ -1476,7 +1562,7 @@ func("string")  # error: [no-matching-overload]
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20non-subscriptable" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1359" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1364" target="_blank">View source</a>
 </small>
 
 
@@ -1500,7 +1586,7 @@ Subscripting an object that does not support it will raise a `TypeError` at runt
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20not-iterable" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1377" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1382" target="_blank">View source</a>
 </small>
 
 
@@ -1526,7 +1612,7 @@ for i in 34:  # TypeError: 'int' object is not iterable
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20parameter-already-assigned" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1428" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1433" target="_blank">View source</a>
 </small>
 
 
@@ -1553,7 +1639,7 @@ f(1, x=2)  # Error raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20positional-only-parameter-as-kwarg" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1663" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1668" target="_blank">View source</a>
 </small>
 
 
@@ -1611,7 +1697,7 @@ def test(): -> "int":
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20static-assert-error" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1785" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1790" target="_blank">View source</a>
 </small>
 
 
@@ -1641,7 +1727,7 @@ static_assert(int(2.0 * 3.0) == 6)  # error: does not have a statically known tr
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20subclass-of-final-class" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1519" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1524" target="_blank">View source</a>
 </small>
 
 
@@ -1670,7 +1756,7 @@ class B(A): ...  # Error raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20too-many-positional-arguments" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1564" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1569" target="_blank">View source</a>
 </small>
 
 
@@ -1697,7 +1783,7 @@ f("foo")  # Error raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20type-assertion-failure" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1542" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1547" target="_blank">View source</a>
 </small>
 
 
@@ -1725,7 +1811,7 @@ def _(x: int):
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unavailable-implicit-super-arguments" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1585" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1590" target="_blank">View source</a>
 </small>
 
 
@@ -1771,7 +1857,7 @@ class A:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unknown-argument" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1642" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1647" target="_blank">View source</a>
 </small>
 
 
@@ -1798,7 +1884,7 @@ f(x=1, y=2)  # Error raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unresolved-attribute" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1684" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1689" target="_blank">View source</a>
 </small>
 
 
@@ -1826,7 +1912,7 @@ A().foo  # AttributeError: 'A' object has no attribute 'foo'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unresolved-import" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1706" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1711" target="_blank">View source</a>
 </small>
 
 
@@ -1851,7 +1937,7 @@ import foo  # ModuleNotFoundError: No module named 'foo'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unresolved-reference" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1725" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1730" target="_blank">View source</a>
 </small>
 
 
@@ -1876,7 +1962,7 @@ print(x)  # NameError: name 'x' is not defined
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unsupported-bool-conversion" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1397" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1402" target="_blank">View source</a>
 </small>
 
 
@@ -1913,7 +1999,7 @@ b1 < b2 < b1  # exception raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unsupported-operator" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1744" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1749" target="_blank">View source</a>
 </small>
 
 
@@ -1941,7 +2027,7 @@ A() + A()  # TypeError: unsupported operand type(s) for +: 'A' and 'A'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20zero-stepsize-in-slice" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1766" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1771" target="_blank">View source</a>
 </small>
 
 
@@ -1966,7 +2052,7 @@ l[1:10:0]  # ValueError: slice step cannot be zero
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.20">0.0.1-alpha.20</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20ambiguous-protocol-member" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L471" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L476" target="_blank">View source</a>
 </small>
 
 
@@ -2007,7 +2093,7 @@ class SubProto(BaseProto, Protocol):
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.16">0.0.1-alpha.16</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20deprecated" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L286" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L291" target="_blank">View source</a>
 </small>
 
 
@@ -2095,7 +2181,7 @@ a = 20 / 0  # type: ignore
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20possibly-missing-attribute" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1449" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1454" target="_blank">View source</a>
 </small>
 
 
@@ -2123,7 +2209,7 @@ A.c  # AttributeError: type object 'A' has no attribute 'c'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20possibly-missing-implicit-call" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L139" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L144" target="_blank">View source</a>
 </small>
 
 
@@ -2155,7 +2241,7 @@ A()[0]  # TypeError: 'A' object is not subscriptable
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20possibly-missing-import" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1471" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1476" target="_blank">View source</a>
 </small>
 
 
@@ -2187,7 +2273,7 @@ from module import a  # ImportError: cannot import name 'a' from 'module'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20redundant-cast" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1837" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1842" target="_blank">View source</a>
 </small>
 
 
@@ -2214,7 +2300,7 @@ cast(int, f())  # Redundant
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20undefined-reveal" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1624" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1629" target="_blank">View source</a>
 </small>
 
 
@@ -2238,7 +2324,7 @@ reveal_type(1)  # NameError: name 'reveal_type' is not defined
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.15">0.0.1-alpha.15</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unresolved-global" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1858" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1863" target="_blank">View source</a>
 </small>
 
 
@@ -2296,7 +2382,7 @@ def g():
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.7">0.0.1-alpha.7</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unsupported-base" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L720" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L725" target="_blank">View source</a>
 </small>
 
 
@@ -2335,7 +2421,7 @@ class D(C): ...  # error: [unsupported-base]
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20useless-overload-body" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1026" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1031" target="_blank">View source</a>
 </small>
 
 
@@ -2398,7 +2484,7 @@ def foo(x: int | str) -> int | str:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'ignore'."><code>ignore</code></a> ·
 Preview (since <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a>) ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20division-by-zero" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L268" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L273" target="_blank">View source</a>
 </small>
 
 
@@ -2422,7 +2508,7 @@ Dividing by zero raises a `ZeroDivisionError` at runtime.
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'ignore'."><code>ignore</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20possibly-unresolved-reference" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1497" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1502" target="_blank">View source</a>
 </small>
 
 

crates/ty/tests/cli/python_environment.rs

@@ -37,7 +37,8 @@ fn config_override_python_version() -> anyhow::Result<()> {
     5 | print(sys.last_exc)
       |       ^^^^^^^^^^^^
       |
-    info: Python 3.11 was assumed when accessing `last_exc`
+    info: The member may be available on other Python versions or platforms
+    info: Python 3.11 was assumed when resolving the `last_exc` attribute
      --> pyproject.toml:3:18
       |
     2 | [tool.ty.environment]
@@ -1179,6 +1180,8 @@ fn defaults_to_a_new_python_version() -> anyhow::Result<()> {
             import os
 
             os.grantpt(1) # only available on unix, Python 3.13 or newer
+
+            from typing import LiteralString  # added in Python 3.11
             "#,
         ),
     ])?;
@@ -1194,8 +1197,11 @@ fn defaults_to_a_new_python_version() -> anyhow::Result<()> {
     3 |
     4 | os.grantpt(1) # only available on unix, Python 3.13 or newer
       | ^^^^^^^^^^
+    5 |
+    6 | from typing import LiteralString  # added in Python 3.11
       |
-    info: Python 3.10 was assumed when accessing `grantpt`
+    info: The member may be available on other Python versions or platforms
+    info: Python 3.10 was assumed when resolving the `grantpt` attribute
      --> ty.toml:3:18
       |
     2 | [environment]
@@ -1205,7 +1211,26 @@ fn defaults_to_a_new_python_version() -> anyhow::Result<()> {
       |
     info: rule `unresolved-attribute` is enabled by default
 
-    Found 1 diagnostic
+    error[unresolved-import]: Module `typing` has no member `LiteralString`
+     --> main.py:6:20
+      |
+    4 | os.grantpt(1) # only available on unix, Python 3.13 or newer
+    5 |
+    6 | from typing import LiteralString  # added in Python 3.11
+      |                    ^^^^^^^^^^^^^
+      |
+    info: The member may be available on other Python versions or platforms
+    info: Python 3.10 was assumed when resolving imports
+     --> ty.toml:3:18
+      |
+    2 | [environment]
+    3 | python-version = "3.10"
+      |                  ^^^^^^ Python 3.10 assumed due to this configuration setting
+    4 | python-platform = "linux"
+      |
+    info: rule `unresolved-import` is enabled by default
+
+    Found 2 diagnostics
 
     ----- stderr -----
     "#);
@@ -1225,6 +1250,8 @@ fn defaults_to_a_new_python_version() -> anyhow::Result<()> {
             import os
 
             os.grantpt(1) # only available on unix, Python 3.13 or newer
+
+            from typing import LiteralString  # added in Python 3.11
             "#,
         ),
     ])?;

crates/ty_completion_eval/completion-evaluation-tasks.csv

@@ -18,11 +18,11 @@ numpy-array,main.py,1,1
 object-attr-instance-methods,main.py,0,1
 object-attr-instance-methods,main.py,1,1
 pass-keyword-completion,main.py,0,1
-raise-uses-base-exception,main.py,0,2
+raise-uses-base-exception,main.py,0,1
 scope-existing-over-new-import,main.py,0,1
 scope-prioritize-closer,main.py,0,2
 scope-simple-long-identifier,main.py,0,1
 tstring-completions,main.py,0,1
 ty-extensions-lower-stdlib,main.py,0,8
 type-var-typing-over-ast,main.py,0,3
-type-var-typing-over-ast,main.py,1,279
+type-var-typing-over-ast,main.py,1,278

crates/ty_ide/src/all_symbols.rs

@@ -8,13 +8,12 @@ use crate::symbols::{QueryPattern, SymbolInfo, symbols_for_file_global_only};
 ///
 /// Returns symbols from all files in the workspace and dependencies, filtered
 /// by the query.
-pub fn all_symbols<'db>(db: &'db dyn Db, query: &str) -> Vec<AllSymbolInfo<'db>> {
+pub fn all_symbols<'db>(db: &'db dyn Db, query: &QueryPattern) -> Vec<AllSymbolInfo<'db>> {
     // If the query is empty, return immediately to avoid expensive file scanning
-    if query.is_empty() {
+    if query.will_match_everything() {
         return Vec::new();
     }
 
-    let query = QueryPattern::new(query);
     let results = std::sync::Mutex::new(Vec::new());
     {
         let modules = all_modules(db);
@@ -144,7 +143,7 @@ ABCDEFGHIJKLMNOP = 'https://api.example.com'
 
     impl CursorTest {
         fn all_symbols(&self, query: &str) -> String {
-            let symbols = all_symbols(&self.db, query);
+            let symbols = all_symbols(&self.db, &QueryPattern::new(query));
 
             if symbols.is_empty() {
                 return "No symbols found".to_string();

crates/ty_ide/src/goto.rs

@@ -15,7 +15,7 @@ use ruff_text_size::{Ranged, TextRange, TextSize};
 use ty_python_semantic::ResolvedDefinition;
 use ty_python_semantic::types::Type;
 use ty_python_semantic::types::ide_support::{
-    call_signature_details, definitions_for_keyword_argument,
+    call_signature_details, call_type_simplified_by_overloads, definitions_for_keyword_argument,
 };
 use ty_python_semantic::{
     HasDefinition, HasType, ImportAliasResolution, SemanticModel, definitions_for_imported_symbol,
@@ -61,6 +61,7 @@ pub(crate) enum GotoTarget<'a> {
     /// ```
     ImportModuleComponent {
         module_name: String,
+        level: u32,
         component_index: usize,
         component_range: TextRange,
     },
@@ -213,6 +214,7 @@ impl<'db> DefinitionsOrTargets<'db> {
             | ty_python_semantic::types::TypeDefinition::Function(definition)
             | ty_python_semantic::types::TypeDefinition::TypeVar(definition)
             | ty_python_semantic::types::TypeDefinition::TypeAlias(definition)
+            | ty_python_semantic::types::TypeDefinition::SpecialForm(definition)
             | ty_python_semantic::types::TypeDefinition::NewType(definition) => {
                 ResolvedDefinition::Definition(definition)
             }
@@ -301,12 +303,21 @@ impl GotoTarget<'_> {
             // (i.e. the type of `MyClass` in `MyClass()` is `<class MyClass>` and not `() -> MyClass`)
             GotoTarget::Call { callable, .. } => callable.inferred_type(model),
             GotoTarget::TypeParamTypeVarName(typevar) => typevar.inferred_type(model),
+            GotoTarget::ImportModuleComponent {
+                module_name,
+                component_index,
+                level,
+                ..
+            } => {
+                // We don't currently support hovering the bare `.` so there is always a name
+                let module = import_name(module_name, *component_index);
+                model.resolve_module_type(Some(module), *level)?
+            }
             // TODO: Support identifier targets
             GotoTarget::PatternMatchRest(_)
             | GotoTarget::PatternKeywordArgument(_)
             | GotoTarget::PatternMatchStarName(_)
             | GotoTarget::PatternMatchAsName(_)
-            | GotoTarget::ImportModuleComponent { .. }
             | GotoTarget::TypeParamParamSpecName(_)
             | GotoTarget::TypeParamTypeVarTupleName(_)
             | GotoTarget::NonLocal { .. }
@@ -326,6 +337,18 @@ impl GotoTarget<'_> {
         Some(ty)
     }
 
+    /// Try to get a simplified display of this callable type by resolving overloads
+    pub(crate) fn call_type_simplified_by_overloads(
+        &self,
+        model: &SemanticModel,
+    ) -> Option<String> {
+        if let GotoTarget::Call { call, .. } = self {
+            call_type_simplified_by_overloads(model.db(), model, call)
+        } else {
+            None
+        }
+    }
+
     /// Gets the definitions for this goto target.
     ///
     /// The `alias_resolution` parameter controls whether import aliases
@@ -340,37 +363,30 @@ impl GotoTarget<'_> {
     /// as just returning a raw `NavigationTarget`.
     pub(crate) fn get_definition_targets<'db>(
         &self,
-        file: ruff_db::files::File,
-        db: &'db dyn crate::Db,
+        model: &SemanticModel<'db>,
         alias_resolution: ImportAliasResolution,
     ) -> Option<DefinitionsOrTargets<'db>> {
         use crate::NavigationTarget;
+        let db = model.db();
+        let file = model.file();
 
         match self {
-            GotoTarget::Expression(expression) => definitions_for_expression(db, file, expression)
-                .map(DefinitionsOrTargets::Definitions),
+            GotoTarget::Expression(expression) => {
+                definitions_for_expression(model, expression).map(DefinitionsOrTargets::Definitions)
+            }
 
             // For already-defined symbols, they are their own definitions
-            GotoTarget::FunctionDef(function) => {
-                let model = SemanticModel::new(db, file);
-                Some(DefinitionsOrTargets::Definitions(vec![
-                    ResolvedDefinition::Definition(function.definition(&model)),
-                ]))
-            }
+            GotoTarget::FunctionDef(function) => Some(DefinitionsOrTargets::Definitions(vec![
+                ResolvedDefinition::Definition(function.definition(model)),
+            ])),
 
-            GotoTarget::ClassDef(class) => {
-                let model = SemanticModel::new(db, file);
-                Some(DefinitionsOrTargets::Definitions(vec![
-                    ResolvedDefinition::Definition(class.definition(&model)),
-                ]))
-            }
+            GotoTarget::ClassDef(class) => Some(DefinitionsOrTargets::Definitions(vec![
+                ResolvedDefinition::Definition(class.definition(model)),
+            ])),
 
-            GotoTarget::Parameter(parameter) => {
-                let model = SemanticModel::new(db, file);
-                Some(DefinitionsOrTargets::Definitions(vec![
-                    ResolvedDefinition::Definition(parameter.definition(&model)),
-                ]))
-            }
+            GotoTarget::Parameter(parameter) => Some(DefinitionsOrTargets::Definitions(vec![
+                ResolvedDefinition::Definition(parameter.definition(model)),
+            ])),
 
             // For import aliases (offset within 'y' or 'z' in "from x import y as z")
             GotoTarget::ImportSymbolAlias {
@@ -391,24 +407,18 @@ impl GotoTarget<'_> {
             GotoTarget::ImportModuleComponent {
                 module_name,
                 component_index,
+                level,
                 ..
             } => {
-                // Handle both `import foo.bar` and `from foo.bar import baz` where offset is within module component
-                let components: Vec<&str> = module_name.split('.').collect();
-
-                // Build the module name up to and including the component containing the offset
-                let target_module_name = components[..=*component_index].join(".");
-
-                // Try to resolve the module
-                definitions_for_module(db, &target_module_name)
+                // We don't currently support hovering the bare `.` so there is always a name
+                let module = import_name(module_name, *component_index);
+                definitions_for_module(model, Some(module), *level)
             }
 
             // Handle import aliases (offset within 'z' in "import x.y as z")
             GotoTarget::ImportModuleAlias { alias } => {
                 if alias_resolution == ImportAliasResolution::ResolveAliases {
-                    let full_module_name = alias.name.as_str();
-                    // Try to resolve the module
-                    definitions_for_module(db, full_module_name)
+                    definitions_for_module(model, Some(alias.name.as_str()), 0)
                 } else {
                     let alias_range = alias.asname.as_ref().unwrap().range;
                     Some(DefinitionsOrTargets::Targets(
@@ -431,9 +441,8 @@ impl GotoTarget<'_> {
 
             // For exception variables, they are their own definitions (like parameters)
             GotoTarget::ExceptVariable(except_handler) => {
-                let model = SemanticModel::new(db, file);
                 Some(DefinitionsOrTargets::Definitions(vec![
-                    ResolvedDefinition::Definition(except_handler.definition(&model)),
+                    ResolvedDefinition::Definition(except_handler.definition(model)),
                 ]))
             }
 
@@ -465,9 +474,9 @@ impl GotoTarget<'_> {
             //
             // Prefer the function impl over the callable so that its docstrings win if defined.
             GotoTarget::Call { callable, call } => {
-                let mut definitions = definitions_for_callable(db, file, call);
+                let mut definitions = definitions_for_callable(model, call);
                 let expr_definitions =
-                    definitions_for_expression(db, file, callable).unwrap_or_default();
+                    definitions_for_expression(model, callable).unwrap_or_default();
                 definitions.extend(expr_definitions);
 
                 if definitions.is_empty() {
@@ -478,18 +487,15 @@ impl GotoTarget<'_> {
             }
 
             GotoTarget::BinOp { expression, .. } => {
-                let model = SemanticModel::new(db, file);
-
                 let (definitions, _) =
-                    ty_python_semantic::definitions_for_bin_op(db, &model, expression)?;
+                    ty_python_semantic::definitions_for_bin_op(db, model, expression)?;
 
                 Some(DefinitionsOrTargets::Definitions(definitions))
             }
 
             GotoTarget::UnaryOp { expression, .. } => {
-                let model = SemanticModel::new(db, file);
                 let (definitions, _) =
-                    ty_python_semantic::definitions_for_unary_op(db, &model, expression)?;
+                    ty_python_semantic::definitions_for_unary_op(db, model, expression)?;
 
                 Some(DefinitionsOrTargets::Definitions(definitions))
             }
@@ -619,6 +625,7 @@ impl GotoTarget<'_> {
                                 {
                                     return Some(GotoTarget::ImportModuleComponent {
                                         module_name: full_name.to_string(),
+                                        level: 0,
                                         component_index,
                                         component_range,
                                     });
@@ -659,14 +666,12 @@ impl GotoTarget<'_> {
                     // Handle offset within module name in from import statements
                     if let Some(module_expr) = &from.module {
                         let full_module_name = module_expr.to_string();
-
-                        if let Some((component_index, component_range)) = find_module_component(
-                            &full_module_name,
-                            module_expr.range.start(),
-                            offset,
-                        ) {
+                        if let Some((component_index, component_range)) =
+                            find_module_component(&full_module_name, module_expr.start(), offset)
+                        {
                             return Some(GotoTarget::ImportModuleComponent {
                                 module_name: full_module_name,
+                                level: from.level,
                                 component_index,
                                 component_range,
                             });
@@ -863,27 +868,26 @@ fn convert_resolved_definitions_to_targets(
 
 /// Shared helper to get definitions for an expr (that is presumably a name/attr)
 fn definitions_for_expression<'db>(
-    db: &'db dyn crate::Db,
-    file: ruff_db::files::File,
+    model: &SemanticModel<'db>,
     expression: &ruff_python_ast::ExprRef<'_>,
 ) -> Option<Vec<ResolvedDefinition<'db>>> {
     match expression {
-        ast::ExprRef::Name(name) => Some(definitions_for_name(db, file, name)),
+        ast::ExprRef::Name(name) => Some(definitions_for_name(model.db(), model.file(), name)),
         ast::ExprRef::Attribute(attribute) => Some(ty_python_semantic::definitions_for_attribute(
-            db, file, attribute,
+            model.db(),
+            model.file(),
+            attribute,
         )),
         _ => None,
     }
 }
 
 fn definitions_for_callable<'db>(
-    db: &'db dyn crate::Db,
-    file: ruff_db::files::File,
+    model: &SemanticModel<'db>,
     call: &ast::ExprCall,
 ) -> Vec<ResolvedDefinition<'db>> {
-    let model = SemanticModel::new(db, file);
     // Attempt to refine to a specific call
-    let signature_info = call_signature_details(db, &model, call);
+    let signature_info = call_signature_details(model.db(), model, call);
     signature_info
         .into_iter()
         .filter_map(|signature| signature.definition.map(ResolvedDefinition::Definition))
@@ -934,7 +938,9 @@ pub(crate) fn find_goto_target(
     }
 
     let covering_node = covering_node(parsed.syntax().into(), token.range())
-        .find_first(|node| node.is_identifier() || node.is_expression())
+        .find_first(|node| {
+            node.is_identifier() || node.is_expression() || node.is_stmt_import_from()
+        })
         .ok()?;
 
     GotoTarget::from_covering_node(&covering_node, offset, parsed.tokens())
@@ -942,21 +948,15 @@ pub(crate) fn find_goto_target(
 
 /// Helper function to resolve a module name and create a navigation target.
 fn definitions_for_module<'db>(
-    db: &'db dyn crate::Db,
-    module_name_str: &str,
+    model: &SemanticModel,
+    module: Option<&str>,
+    level: u32,
 ) -> Option<DefinitionsOrTargets<'db>> {
-    use ty_python_semantic::{ModuleName, resolve_module};
-
-    if let Some(module_name) = ModuleName::new(module_name_str) {
-        if let Some(resolved_module) = resolve_module(db, &module_name) {
-            if let Some(module_file) = resolved_module.file(db) {
-                return Some(DefinitionsOrTargets::Definitions(vec![
-                    ResolvedDefinition::Module(module_file),
-                ]));
-            }
-        }
-    }
-    None
+    let module = model.resolve_module(module, level)?;
+    let file = module.file(model.db())?;
+    Some(DefinitionsOrTargets::Definitions(vec![
+        ResolvedDefinition::Module(file),
+    ]))
 }
 
 /// Helper function to extract module component information from a dotted module name
@@ -970,9 +970,7 @@ fn find_module_component(
 
     // Split the module name into components and find which one contains the offset
     let mut current_pos = 0;
-    let components: Vec<&str> = full_module_name.split('.').collect();
-
-    for (i, component) in components.iter().enumerate() {
+    for (i, component) in full_module_name.split('.').enumerate() {
         let component_start = current_pos;
         let component_end = current_pos + component.len();
 
@@ -991,3 +989,16 @@ fn find_module_component(
 
     None
 }
+
+/// Helper to get the module name up to the given component index
+fn import_name(module_name: &str, component_index: usize) -> &str {
+    // We want everything to the left of the nth `.`
+    // If there's no nth `.` then we want the whole thing.
+    let idx = module_name
+        .match_indices('.')
+        .nth(component_index)
+        .map(|(idx, _)| idx)
+        .unwrap_or(module_name.len());
+
+    &module_name[..idx]
+}

crates/ty_ide/src/goto_declaration.rs

@@ -3,7 +3,7 @@ use crate::{Db, NavigationTargets, RangedValue};
 use ruff_db::files::{File, FileRange};
 use ruff_db::parsed::parsed_module;
 use ruff_text_size::{Ranged, TextSize};
-use ty_python_semantic::ImportAliasResolution;
+use ty_python_semantic::{ImportAliasResolution, SemanticModel};
 
 /// Navigate to the declaration of a symbol.
 ///
@@ -18,8 +18,9 @@ pub fn goto_declaration(
     let module = parsed_module(db, file).load(db);
     let goto_target = find_goto_target(&module, offset)?;
 
+    let model = SemanticModel::new(db, file);
     let declaration_targets = goto_target
-        .get_definition_targets(file, db, ImportAliasResolution::ResolveAliases)?
+        .get_definition_targets(&model, ImportAliasResolution::ResolveAliases)?
         .declaration_targets(db)?;
 
     Some(RangedValue {

crates/ty_ide/src/goto_definition.rs

@@ -3,7 +3,7 @@ use crate::{Db, NavigationTargets, RangedValue};
 use ruff_db::files::{File, FileRange};
 use ruff_db::parsed::parsed_module;
 use ruff_text_size::{Ranged, TextSize};
-use ty_python_semantic::ImportAliasResolution;
+use ty_python_semantic::{ImportAliasResolution, SemanticModel};
 
 /// Navigate to the definition of a symbol.
 ///
@@ -18,9 +18,9 @@ pub fn goto_definition(
 ) -> Option<RangedValue<NavigationTargets>> {
     let module = parsed_module(db, file).load(db);
     let goto_target = find_goto_target(&module, offset)?;
-
+    let model = SemanticModel::new(db, file);
     let definition_targets = goto_target
-        .get_definition_targets(file, db, ImportAliasResolution::ResolveAliases)?
+        .get_definition_targets(&model, ImportAliasResolution::ResolveAliases)?
         .definition_targets(db)?;
 
     Some(RangedValue {

crates/ty_ide/src/goto_type_definition.rs

@@ -68,6 +68,134 @@ mod tests {
         ");
     }
 
+    #[test]
+    fn goto_type_of_typing_dot_literal() {
+        let test = cursor_test(
+            r#"
+            from typing import Literal
+
+            a<CURSOR>b = Literal
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info[goto-type-definition]: Type definition
+           --> stdlib/typing.pyi:351:1
+            |
+        349 | Final: _SpecialForm
+        350 |
+        351 | Literal: _SpecialForm
+            | ^^^^^^^
+        352 | TypedDict: _SpecialForm
+            |
+        info: Source
+         --> main.py:4:1
+          |
+        2 | from typing import Literal
+        3 |
+        4 | ab = Literal
+          | ^^
+          |
+        ");
+    }
+
+    // this is a slightly different case to the one above,
+    // since `Any` is a class in typeshed rather than a variable
+    #[test]
+    fn goto_type_of_typing_dot_any() {
+        let test = cursor_test(
+            r#"
+            from typing import Any
+
+            a<CURSOR>b = Any
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r#"
+        info[goto-type-definition]: Type definition
+           --> stdlib/typing.pyi:166:7
+            |
+        164 | # from _typeshed import AnnotationForm
+        165 |
+        166 | class Any:
+            |       ^^^
+        167 |     """Special type indicating an unconstrained type.
+            |
+        info: Source
+         --> main.py:4:1
+          |
+        2 | from typing import Any
+        3 |
+        4 | ab = Any
+          | ^^
+          |
+        "#);
+    }
+
+    // Similarly, `Generic` is a `type[]` type in typeshed
+    #[test]
+    fn goto_type_of_typing_dot_generic() {
+        let test = cursor_test(
+            r#"
+            from typing import Generic
+
+            a<CURSOR>b = Generic
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info[goto-type-definition]: Type definition
+           --> stdlib/typing.pyi:770:1
+            |
+        768 |         def __class_getitem__(cls, args: TypeVar | tuple[TypeVar, ...]) -> _Final: ...
+        769 |
+        770 | Generic: type[_Generic]
+            | ^^^^^^^
+        771 |
+        772 | class _ProtocolMeta(ABCMeta):
+            |
+        info: Source
+         --> main.py:4:1
+          |
+        2 | from typing import Generic
+        3 |
+        4 | ab = Generic
+          | ^^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_ty_extensions_special_form() {
+        let test = cursor_test(
+            r#"
+            from ty_extensions import AlwaysTruthy
+
+            a<CURSOR>b = AlwaysTruthy
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info[goto-type-definition]: Type definition
+          --> stdlib/ty_extensions.pyi:21:1
+           |
+        19 | # Types
+        20 | Unknown = object()
+        21 | AlwaysTruthy = object()
+           | ^^^^^^^^^^^^
+        22 | AlwaysFalsy = object()
+           |
+        info: Source
+         --> main.py:4:1
+          |
+        2 | from ty_extensions import AlwaysTruthy
+        3 |
+        4 | ab = AlwaysTruthy
+          | ^^
+          |
+        ");
+    }
+
     #[test]
     fn goto_type_of_expression_with_function_type() {
         let test = cursor_test(
@@ -157,6 +285,300 @@ mod tests {
         ");
     }
 
+    #[test]
+    fn goto_type_of_import_module() {
+        let mut test = cursor_test(
+            r#"
+            import l<CURSOR>ib
+            "#,
+        );
+
+        test.write_file("lib.py", "a = 10").unwrap();
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info[goto-type-definition]: Type definition
+         --> lib.py:1:1
+          |
+        1 | a = 10
+          | ^^^^^^
+          |
+        info: Source
+         --> main.py:2:8
+          |
+        2 | import lib
+          |        ^^^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_import_module_multi1() {
+        let mut test = cursor_test(
+            r#"
+            import li<CURSOR>b.submod
+            "#,
+        );
+
+        test.write_file("lib/__init__.py", "b = 7").unwrap();
+        test.write_file("lib/submod.py", "a = 10").unwrap();
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info[goto-type-definition]: Type definition
+         --> lib/__init__.py:1:1
+          |
+        1 | b = 7
+          | ^^^^^
+          |
+        info: Source
+         --> main.py:2:8
+          |
+        2 | import lib.submod
+          |        ^^^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_import_module_multi2() {
+        let mut test = cursor_test(
+            r#"
+            import lib.subm<CURSOR>od
+            "#,
+        );
+
+        test.write_file("lib/__init__.py", "b = 7").unwrap();
+        test.write_file("lib/submod.py", "a = 10").unwrap();
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info[goto-type-definition]: Type definition
+         --> lib/submod.py:1:1
+          |
+        1 | a = 10
+          | ^^^^^^
+          |
+        info: Source
+         --> main.py:2:12
+          |
+        2 | import lib.submod
+          |            ^^^^^^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_from_import_module() {
+        let mut test = cursor_test(
+            r#"
+            from l<CURSOR>ib import a
+            "#,
+        );
+
+        test.write_file("lib.py", "a = 10").unwrap();
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info[goto-type-definition]: Type definition
+         --> lib.py:1:1
+          |
+        1 | a = 10
+          | ^^^^^^
+          |
+        info: Source
+         --> main.py:2:6
+          |
+        2 | from lib import a
+          |      ^^^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_from_import_module_multi1() {
+        let mut test = cursor_test(
+            r#"
+            from li<CURSOR>b.submod import a
+            "#,
+        );
+
+        test.write_file("lib/__init__.py", "b = 7").unwrap();
+        test.write_file("lib/submod.py", "a = 10").unwrap();
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info[goto-type-definition]: Type definition
+         --> lib/__init__.py:1:1
+          |
+        1 | b = 7
+          | ^^^^^
+          |
+        info: Source
+         --> main.py:2:6
+          |
+        2 | from lib.submod import a
+          |      ^^^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_from_import_module_multi2() {
+        let mut test = cursor_test(
+            r#"
+            from lib.subm<CURSOR>od import a
+            "#,
+        );
+
+        test.write_file("lib/__init__.py", "b = 7").unwrap();
+        test.write_file("lib/submod.py", "a = 10").unwrap();
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info[goto-type-definition]: Type definition
+         --> lib/submod.py:1:1
+          |
+        1 | a = 10
+          | ^^^^^^
+          |
+        info: Source
+         --> main.py:2:10
+          |
+        2 | from lib.submod import a
+          |          ^^^^^^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_from_import_rel1() {
+        let mut test = CursorTest::builder()
+            .source(
+                "lib/sub/__init__.py",
+                r#"
+            from .bot.bot<CURSOR>mod import *
+            sub = 2
+            "#,
+            )
+            .build();
+
+        test.write_file("lib/__init__.py", "lib = 1").unwrap();
+        // test.write_file("lib/sub/__init__.py", "sub = 2").unwrap();
+        test.write_file("lib/sub/bot/__init__.py", "bot = 3")
+            .unwrap();
+        test.write_file("lib/sub/submod.py", "submod = 21").unwrap();
+        test.write_file("lib/sub/bot/botmod.py", "botmod = 31")
+            .unwrap();
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info[goto-type-definition]: Type definition
+         --> lib/sub/bot/botmod.py:1:1
+          |
+        1 | botmod = 31
+          | ^^^^^^^^^^^
+          |
+        info: Source
+         --> lib/sub/__init__.py:2:11
+          |
+        2 | from .bot.botmod import *
+          |           ^^^^^^
+        3 | sub = 2
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_from_import_rel2() {
+        let mut test = CursorTest::builder()
+            .source(
+                "lib/sub/__init__.py",
+                r#"
+            from .bo<CURSOR>t.botmod import *
+            sub = 2
+            "#,
+            )
+            .build();
+
+        test.write_file("lib/__init__.py", "lib = 1").unwrap();
+        // test.write_file("lib/sub/__init__.py", "sub = 2").unwrap();
+        test.write_file("lib/sub/bot/__init__.py", "bot = 3")
+            .unwrap();
+        test.write_file("lib/sub/submod.py", "submod = 21").unwrap();
+        test.write_file("lib/sub/bot/botmod.py", "botmod = 31")
+            .unwrap();
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info[goto-type-definition]: Type definition
+         --> lib/sub/bot/__init__.py:1:1
+          |
+        1 | bot = 3
+          | ^^^^^^^
+          |
+        info: Source
+         --> lib/sub/__init__.py:2:7
+          |
+        2 | from .bot.botmod import *
+          |       ^^^
+        3 | sub = 2
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_from_import_rel3() {
+        let mut test = CursorTest::builder()
+            .source(
+                "lib/sub/__init__.py",
+                r#"
+            from .<CURSOR>bot.botmod import *
+            sub = 2
+            "#,
+            )
+            .build();
+
+        test.write_file("lib/__init__.py", "lib = 1").unwrap();
+        // test.write_file("lib/sub/__init__.py", "sub = 2").unwrap();
+        test.write_file("lib/sub/bot/__init__.py", "bot = 3")
+            .unwrap();
+        test.write_file("lib/sub/submod.py", "submod = 21").unwrap();
+        test.write_file("lib/sub/bot/botmod.py", "botmod = 31")
+            .unwrap();
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info[goto-type-definition]: Type definition
+         --> lib/sub/bot/__init__.py:1:1
+          |
+        1 | bot = 3
+          | ^^^^^^^
+          |
+        info: Source
+         --> lib/sub/__init__.py:2:7
+          |
+        2 | from .bot.botmod import *
+          |       ^^^
+        3 | sub = 2
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_from_import_rel4() {
+        let mut test = CursorTest::builder()
+            .source(
+                "lib/sub/__init__.py",
+                r#"
+            from .<CURSOR> import submod
+            sub = 2
+            "#,
+            )
+            .build();
+
+        test.write_file("lib/__init__.py", "lib = 1").unwrap();
+        // test.write_file("lib/sub/__init__.py", "sub = 2").unwrap();
+        test.write_file("lib/sub/bot/__init__.py", "bot = 3")
+            .unwrap();
+        test.write_file("lib/sub/submod.py", "submod = 21").unwrap();
+        test.write_file("lib/sub/bot/botmod.py", "botmod = 31")
+            .unwrap();
+
+        assert_snapshot!(test.goto_type_definition(), @"No goto target found");
+    }
+
     #[test]
     fn goto_type_of_expression_with_module() {
         let mut test = cursor_test(

crates/ty_ide/src/hover.rs

@@ -20,19 +20,18 @@ pub fn hover(db: &dyn Db, file: File, offset: TextSize) -> Option<RangedValue<Ho
     }
 
     let model = SemanticModel::new(db, file);
-    let ty = goto_target.inferred_type(&model);
     let docs = goto_target
         .get_definition_targets(
-            file,
-            db,
+            &model,
             ty_python_semantic::ImportAliasResolution::ResolveAliases,
         )
         .and_then(|definitions| definitions.docstring(db))
         .map(HoverContent::Docstring);
 
-    // TODO: Render the symbol's signature instead of just its type.
     let mut contents = Vec::new();
-    if let Some(ty) = ty {
+    if let Some(signature) = goto_target.call_type_simplified_by_overloads(&model) {
+        contents.push(HoverContent::Signature(signature));
+    } else if let Some(ty) = goto_target.inferred_type(&model) {
         tracing::debug!("Inferred type of covering node is {}", ty.display(db));
         contents.push(match ty {
             Type::KnownInstance(KnownInstanceType::TypeVar(typevar)) => typevar
@@ -62,7 +61,7 @@ pub struct Hover<'db> {
 
 impl<'db> Hover<'db> {
     /// Renders the hover to a string using the specified markup kind.
-    pub const fn display<'a>(&'a self, db: &'a dyn Db, kind: MarkupKind) -> DisplayHover<'a> {
+    pub const fn display<'a>(&'a self, db: &'db dyn Db, kind: MarkupKind) -> DisplayHover<'db, 'a> {
         DisplayHover {
             db,
             hover: self,
@@ -93,13 +92,13 @@ impl<'a, 'db> IntoIterator for &'a Hover<'db> {
     }
 }
 
-pub struct DisplayHover<'a> {
-    db: &'a dyn Db,
-    hover: &'a Hover<'a>,
+pub struct DisplayHover<'db, 'a> {
+    db: &'db dyn Db,
+    hover: &'a Hover<'db>,
     kind: MarkupKind,
 }
 
-impl fmt::Display for DisplayHover<'_> {
+impl fmt::Display for DisplayHover<'_, '_> {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         let mut first = true;
         for content in &self.hover.contents {
@@ -115,8 +114,9 @@ impl fmt::Display for DisplayHover<'_> {
     }
 }
 
-#[derive(Debug, Clone, Eq, PartialEq)]
+#[derive(Debug, Clone)]
 pub enum HoverContent<'db> {
+    Signature(String),
     Type(Type<'db>, Option<TypeVarVariance>),
     Docstring(Docstring),
 }
@@ -140,6 +140,9 @@ pub(crate) struct DisplayHoverContent<'a, 'db> {
 impl fmt::Display for DisplayHoverContent<'_, '_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self.content {
+            HoverContent::Signature(signature) => {
+                self.kind.fenced_code_block(&signature, "python").fmt(f)
+            }
             HoverContent::Type(ty, variance) => {
                 let variance = match variance {
                     Some(TypeVarVariance::Covariant) => " (covariant)",
@@ -241,14 +244,11 @@ mod tests {
         ) -> Unknown
         ```
         ---
-        ```text
-        This is such a great func!!
-
-        Args:
-            a: first for a reason
-            b: coming for `a`'s title
-
-        ```
+        This is such a great func!!  
+          
+        Args:  
+        &nbsp;&nbsp;&nbsp;&nbsp;a: first for a reason  
+        &nbsp;&nbsp;&nbsp;&nbsp;b: coming for `a`'s title
         ---------------------------------------------
         info[hover]: Hovered content is
           --> main.py:11:1
@@ -299,14 +299,11 @@ mod tests {
         ) -> Unknown
         ```
         ---
-        ```text
-        This is such a great func!!
-
-        Args:
-            a: first for a reason
-            b: coming for `a`'s title
-
-        ```
+        This is such a great func!!  
+          
+        Args:  
+        &nbsp;&nbsp;&nbsp;&nbsp;a: first for a reason  
+        &nbsp;&nbsp;&nbsp;&nbsp;b: coming for `a`'s title
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:2:5
@@ -365,14 +362,11 @@ mod tests {
         <class 'MyClass'>
         ```
         ---
-        ```text
-        This is such a great class!!
-
-            Don't you know?
-
+        This is such a great class!!  
+          
+        &nbsp;&nbsp;&nbsp;&nbsp;Don't you know?  
+          
         Everyone loves my class!!
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
           --> main.py:24:1
@@ -430,14 +424,11 @@ mod tests {
         <class 'MyClass'>
         ```
         ---
-        ```text
-        This is such a great class!!
-
-            Don't you know?
-
+        This is such a great class!!  
+          
+        &nbsp;&nbsp;&nbsp;&nbsp;Don't you know?  
+          
         Everyone loves my class!!
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:2:7
@@ -493,10 +484,7 @@ mod tests {
         <class 'MyClass'>
         ```
         ---
-        ```text
         initializes MyClass (perfectly)
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
           --> main.py:24:5
@@ -552,10 +540,7 @@ mod tests {
         <class 'MyClass'>
         ```
         ---
-        ```text
         initializes MyClass (perfectly)
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:4:11
@@ -614,14 +599,11 @@ mod tests {
         <class 'MyClass'>
         ```
         ---
-        ```text
-        This is such a great class!!
-
-            Don't you know?
-
+        This is such a great class!!  
+          
+        &nbsp;&nbsp;&nbsp;&nbsp;Don't you know?  
+          
         Everyone loves my class!!
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
           --> main.py:23:5
@@ -688,14 +670,11 @@ mod tests {
         ) -> Unknown
         ```
         ---
-        ```text
-        This is such a great func!!
-
-        Args:
-            a: first for a reason
-            b: coming for `a`'s title
-
-        ```
+        This is such a great func!!  
+          
+        Args:  
+        &nbsp;&nbsp;&nbsp;&nbsp;a: first for a reason  
+        &nbsp;&nbsp;&nbsp;&nbsp;b: coming for `a`'s title
         ---------------------------------------------
         info[hover]: Hovered content is
           --> main.py:25:3
@@ -961,20 +940,15 @@ def ab(a: str): ...
 
         assert_snapshot!(test.hover(), @r"
         (a: int) -> Unknown
-        (a: str) -> Unknown
         ---------------------------------------------
         the int overload
 
         ---------------------------------------------
         ```python
         (a: int) -> Unknown
-        (a: str) -> Unknown
         ```
         ---
-        ```text
         the int overload
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:4:1
@@ -1025,21 +999,16 @@ def ab(a: str):
             .build();
 
         assert_snapshot!(test.hover(), @r#"
-        (a: int) -> Unknown
         (a: str) -> Unknown
         ---------------------------------------------
         the int overload
 
         ---------------------------------------------
         ```python
-        (a: int) -> Unknown
         (a: str) -> Unknown
         ```
         ---
-        ```text
         the int overload
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:4:1
@@ -1094,7 +1063,6 @@ def ab(a: int):
             a: int,
             b: int
         ) -> Unknown
-        (a: int) -> Unknown
         ---------------------------------------------
         the two arg overload
 
@@ -1104,13 +1072,9 @@ def ab(a: int):
             a: int,
             b: int
         ) -> Unknown
-        (a: int) -> Unknown
         ```
         ---
-        ```text
         the two arg overload
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:4:1
@@ -1161,27 +1125,16 @@ def ab(a: int):
             .build();
 
         assert_snapshot!(test.hover(), @r"
-        (
-            a: int,
-            b: int
-        ) -> Unknown
         (a: int) -> Unknown
         ---------------------------------------------
         the two arg overload
 
         ---------------------------------------------
         ```python
-        (
-            a: int,
-            b: int
-        ) -> Unknown
         (a: int) -> Unknown
         ```
         ---
-        ```text
         the two arg overload
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:4:1
@@ -1236,39 +1189,24 @@ def ab(a: int, *, c: int):
             .build();
 
         assert_snapshot!(test.hover(), @r"
-        (a: int) -> Unknown
         (
             a: int,
             *,
             b: int
         ) -> Unknown
-        (
-            a: int,
-            *,
-            c: int
-        ) -> Unknown
         ---------------------------------------------
         keywordless overload
 
         ---------------------------------------------
         ```python
-        (a: int) -> Unknown
         (
             a: int,
             *,
             b: int
         ) -> Unknown
-        (
-            a: int,
-            *,
-            c: int
-        ) -> Unknown
         ```
         ---
-        ```text
         keywordless overload
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:4:1
@@ -1323,12 +1261,6 @@ def ab(a: int, *, c: int):
             .build();
 
         assert_snapshot!(test.hover(), @r"
-        (a: int) -> Unknown
-        (
-            a: int,
-            *,
-            b: int
-        ) -> Unknown
         (
             a: int,
             *,
@@ -1339,12 +1271,6 @@ def ab(a: int, *, c: int):
 
         ---------------------------------------------
         ```python
-        (a: int) -> Unknown
-        (
-            a: int,
-            *,
-            b: int
-        ) -> Unknown
         (
             a: int,
             *,
@@ -1352,10 +1278,7 @@ def ab(a: int, *, c: int):
         ) -> Unknown
         ```
         ---
-        ```text
         keywordless overload
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:4:1
@@ -1420,10 +1343,7 @@ def ab(a: int, *, c: int):
         ) -> Unknown
         ```
         ---
-        ```text
         The first overload
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
           --> main.py:19:1
@@ -1475,10 +1395,7 @@ def ab(a: int, *, c: int):
         (a: str) -> Unknown
         ```
         ---
-        ```text
         The first overload
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
           --> main.py:19:1
@@ -1528,12 +1445,9 @@ def ab(a: int, *, c: int):
         <module 'lib'>
         ```
         ---
-        ```text
-        The cool lib_py module!
-
+        The cool lib/_py module!  
+          
         Wow this module rocks.
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:4:1
@@ -1573,17 +1487,20 @@ def ab(a: int, *, c: int):
         .unwrap();
 
         assert_snapshot!(test.hover(), @r"
+        <module 'lib'>
+        ---------------------------------------------
         The cool lib_py module!
 
         Wow this module rocks.
 
         ---------------------------------------------
-        ```text
-        The cool lib_py module!
-
-        Wow this module rocks.
-
+        ```python
+        <module 'lib'>
         ```
+        ---
+        The cool lib/_py module!  
+          
+        Wow this module rocks.
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:2:8
@@ -2533,10 +2450,7 @@ def ab(a: int, *, c: int):
         bound method int.__add__(value: int, /) -> int
         ```
         ---
-        ```text
         Return self+value.
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:2:12
@@ -2652,10 +2566,7 @@ def ab(a: int, *, c: int):
         int | float
         ```
         ---
-        ```text
         Convert a string or number to a floating-point number, if possible.
-
-        ```
         ---------------------------------------------
         info[hover]: Hovered content is
          --> main.py:2:4

crates/ty_ide/src/references.rs

@@ -20,7 +20,7 @@ use ruff_python_ast::{
 };
 use ruff_python_parser::Tokens;
 use ruff_text_size::{Ranged, TextRange};
-use ty_python_semantic::ImportAliasResolution;
+use ty_python_semantic::{ImportAliasResolution, SemanticModel};
 
 /// Mode for references search behavior
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -48,8 +48,9 @@ pub(crate) fn references(
     // Get the definitions for the symbol at the cursor position
 
     // When finding references, do not resolve any local aliases.
+    let model = SemanticModel::new(db, file);
     let target_definitions_nav = goto_target
-        .get_definition_targets(file, db, ImportAliasResolution::PreserveAliases)?
+        .get_definition_targets(&model, ImportAliasResolution::PreserveAliases)?
         .definition_targets(db)?;
     let target_definitions: Vec<NavigationTarget> = target_definitions_nav.into_iter().collect();
 
@@ -289,8 +290,9 @@ impl LocalReferencesFinder<'_> {
             GotoTarget::from_covering_node(covering_node, offset, self.tokens)
         {
             // Get the definitions for this goto target
+            let model = SemanticModel::new(self.db, self.file);
             if let Some(current_definitions_nav) = goto_target
-                .get_definition_targets(self.file, self.db, ImportAliasResolution::PreserveAliases)
+                .get_definition_targets(&model, ImportAliasResolution::PreserveAliases)
                 .and_then(|definitions| definitions.declaration_targets(self.db))
             {
                 let current_definitions: Vec<NavigationTarget> =

crates/ty_ide/src/rename.rs

@@ -3,12 +3,13 @@ use crate::references::{ReferencesMode, references};
 use crate::{Db, ReferenceTarget};
 use ruff_db::files::File;
 use ruff_text_size::{Ranged, TextSize};
-use ty_python_semantic::ImportAliasResolution;
+use ty_python_semantic::{ImportAliasResolution, SemanticModel};
 
 /// Returns the range of the symbol if it can be renamed, None if not.
 pub fn can_rename(db: &dyn Db, file: File, offset: TextSize) -> Option<ruff_text_size::TextRange> {
     let parsed = ruff_db::parsed::parsed_module(db, file);
     let module = parsed.load(db);
+    let model = SemanticModel::new(db, file);
 
     // Get the definitions for the symbol at the offset
     let goto_target = find_goto_target(&module, offset)?;
@@ -24,7 +25,7 @@ pub fn can_rename(db: &dyn Db, file: File, offset: TextSize) -> Option<ruff_text
     let current_file_in_project = is_file_in_project(db, file);
 
     if let Some(definition_targets) = goto_target
-        .get_definition_targets(file, db, ImportAliasResolution::PreserveAliases)
+        .get_definition_targets(&model, ImportAliasResolution::PreserveAliases)
         .and_then(|definitions| definitions.declaration_targets(db))
     {
         for target in &definition_targets {

crates/ty_ide/src/symbols.rs

@@ -67,6 +67,16 @@ impl QueryPattern {
             symbol_name.contains(&self.original)
         }
     }
+
+    /// Returns true when it is known that this pattern will return `true` for
+    /// all inputs given to `QueryPattern::is_match_symbol_name`.
+    ///
+    /// This will never return `true` incorrectly, but it may return `false`
+    /// incorrectly. That is, it's possible that this query will match all
+    /// inputs but this still returns `false`.
+    pub fn will_match_everything(&self) -> bool {
+        self.re.is_none()
+    }
 }
 
 impl From<&str> for QueryPattern {

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

@@ -12,11 +12,8 @@ P = ParamSpec("P")
 Ts = TypeVarTuple("Ts")
 R_co = TypeVar("R_co", covariant=True)
 
-Alias: TypeAlias = int
-
 def f(*args: Unpack[Ts]) -> tuple[Unpack[Ts]]:
     reveal_type(args)  # revealed: tuple[@Todo(`Unpack[]` special form), ...]
-    reveal_type(Alias)  # revealed: @Todo(Support for `typing.TypeAlias`)
     return args
 
 def g() -> TypeGuard[int]: ...

crates/ty_python_semantic/resources/mdtest/assignment/annotations.md

@@ -482,17 +482,14 @@ class TD2(TypedDict):
     x: str
 
 def f(self, dt: dict[str, Any], key: str):
-    # TODO: This should not error once typed dict assignability is implemented.
-    # error: [invalid-assignment]
     x1: TD = dt.get(key, {})
-    reveal_type(x1)  # revealed: TD
+    reveal_type(x1)  # revealed: Any
 
     x2: TD = dt.get(key, {"x": 0})
     reveal_type(x2)  # revealed: Any
 
     x3: TD | None = dt.get(key, {})
-    # TODO: This should reveal `Any` once typed dict assignability is implemented.
-    reveal_type(x3)  # revealed: Any | None
+    reveal_type(x3)  # revealed: Any
 
     x4: TD | None = dt.get(key, {"x": 0})
     reveal_type(x4)  # revealed: Any
@@ -718,3 +715,17 @@ def _(a: int, b: str, c: int | str):
     x9: int | str | None = f(lst(c))
     reveal_type(x9)  # revealed: int | str | None
 ```
+
+## Forward annotation with unclosed string literal
+
+Regression test for [#1611](https://github.com/astral-sh/ty/issues/1611).
+
+<!-- blacken-docs:off -->
+
+```py
+# error: [invalid-syntax]
+# error: [invalid-syntax-in-forward-annotation]
+a:'
+```
+
+<!-- blacken-docs:on -->

crates/ty_python_semantic/resources/mdtest/attributes.md

@@ -1904,6 +1904,7 @@ we only consider the attribute assignment to be valid if the assigned attribute
 from typing import Literal
 
 class Date:
+    # error: [invalid-method-override]
     def __setattr__(self, name: Literal["day", "month", "year"], value: int) -> None:
         pass
 
@@ -2208,9 +2209,9 @@ reveal_type(False.real)  # revealed: Literal[0]
 All attribute access on literal `bytes` types is currently delegated to `builtins.bytes`:
 
 ```py
-# revealed: bound method Literal[b"foo"].join(iterable_of_bytes: Iterable[@Todo(Support for `typing.TypeAlias`)], /) -> bytes
+# revealed: bound method Literal[b"foo"].join(iterable_of_bytes: Iterable[Buffer], /) -> bytes
 reveal_type(b"foo".join)
-# revealed: bound method Literal[b"foo"].endswith(suffix: @Todo(Support for `typing.TypeAlias`) | tuple[@Todo(Support for `typing.TypeAlias`), ...], start: SupportsIndex | None = None, end: SupportsIndex | None = None, /) -> bool
+# revealed: bound method Literal[b"foo"].endswith(suffix: Buffer | tuple[Buffer, ...], start: SupportsIndex | None = None, end: SupportsIndex | None = None, /) -> bool
 reveal_type(b"foo".endswith)
 ```
 
@@ -2683,6 +2684,39 @@ reveal_type(datetime.UTC)  # revealed: Unknown
 reveal_type(datetime.fakenotreal)  # revealed: Unknown
 ```
 
+## Unimported submodule incorrectly accessed as attribute
+
+We give special diagnostics for this common case too:
+
+<!-- snapshot-diagnostics -->
+
+`foo/__init__.py`:
+
+```py
+```
+
+`foo/bar.py`:
+
+```py
+```
+
+`baz/bar.py`:
+
+```py
+```
+
+`main.py`:
+
+```py
+import foo
+import baz
+
+# error: [possibly-missing-attribute]
+reveal_type(foo.bar)  # revealed: <module 'foo.bar'>
+# error: [possibly-missing-attribute]
+reveal_type(baz.bar)  # revealed: <module 'baz.bar'>
+```
+
 ## References
 
 Some of the tests in the *Class and instance variables* section draw inspiration from

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

@@ -313,8 +313,7 @@ reveal_type(A() + "foo")  # revealed: A
 reveal_type("foo" + A())  # revealed: A
 
 reveal_type(A() + b"foo")  # revealed: A
-# TODO should be `A` since `bytes.__add__` doesn't support `A` instances
-reveal_type(b"foo" + A())  # revealed: bytes
+reveal_type(b"foo" + A())  # revealed: A
 
 reveal_type(A() + ())  # revealed: A
 reveal_type(() + A())  # revealed: A

crates/ty_python_semantic/resources/mdtest/binary/integers.md

@@ -54,10 +54,8 @@ reveal_type(2**largest_u32)  # revealed: int
 
 def variable(x: int):
     reveal_type(x**2)  # revealed: int
-    # TODO: should be `Any` (overload 5 on `__pow__`), requires correct overload matching
-    reveal_type(2**x)  # revealed: int
-    # TODO: should be `Any` (overload 5 on `__pow__`), requires correct overload matching
-    reveal_type(x**x)  # revealed: int
+    reveal_type(2**x)  # revealed: Any
+    reveal_type(x**x)  # revealed: Any
 ```
 
 If the second argument is \<0, a `float` is returned at runtime. If the first argument is \<0 but

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

@@ -598,9 +598,9 @@ from typing_extensions import Self
 
 reveal_type(object.__new__)  # revealed: def __new__(cls) -> Self@__new__
 reveal_type(object().__new__)  # revealed: def __new__(cls) -> Self@__new__
-# revealed: Overload[(cls, x: @Todo(Support for `typing.TypeAlias`) = Literal[0], /) -> Self@__new__, (cls, x: str | bytes | bytearray, /, base: SupportsIndex) -> Self@__new__]
+# revealed: Overload[(cls, x: str | Buffer | SupportsInt | SupportsIndex | SupportsTrunc = Literal[0], /) -> Self@__new__, (cls, x: str | bytes | bytearray, /, base: SupportsIndex) -> Self@__new__]
 reveal_type(int.__new__)
-# revealed: Overload[(cls, x: @Todo(Support for `typing.TypeAlias`) = Literal[0], /) -> Self@__new__, (cls, x: str | bytes | bytearray, /, base: SupportsIndex) -> Self@__new__]
+# revealed: Overload[(cls, x: str | Buffer | SupportsInt | SupportsIndex | SupportsTrunc = Literal[0], /) -> Self@__new__, (cls, x: str | bytes | bytearray, /, base: SupportsIndex) -> Self@__new__]
 reveal_type((42).__new__)
 
 class X:

crates/ty_python_semantic/resources/mdtest/call/open.md

@@ -10,13 +10,13 @@ import pickle
 
 reveal_type(open(""))  # revealed: TextIOWrapper[_WrappedBuffer]
 reveal_type(open("", "r"))  # revealed: TextIOWrapper[_WrappedBuffer]
-reveal_type(open("", "rb"))  # revealed: @Todo(`builtins.open` return type)
+reveal_type(open("", "rb"))  # revealed: BufferedReader[_BufferedReaderStream]
 
 with open("foo.pickle", "rb") as f:
     x = pickle.load(f)  # fine
 
 def _(mode: str):
-    reveal_type(open("", mode))  # revealed: @Todo(`builtins.open` return type)
+    reveal_type(open("", mode))  # revealed: IO[Any]
 ```
 
 ## `os.fdopen`
@@ -29,7 +29,7 @@ import os
 
 reveal_type(os.fdopen(0))  # revealed: TextIOWrapper[_WrappedBuffer]
 reveal_type(os.fdopen(0, "r"))  # revealed: TextIOWrapper[_WrappedBuffer]
-reveal_type(os.fdopen(0, "rb"))  # revealed: @Todo(`os.fdopen` return type)
+reveal_type(os.fdopen(0, "rb"))  # revealed: BufferedReader[_BufferedReaderStream]
 
 with os.fdopen(0, "rb") as f:
     x = pickle.load(f)  # fine
@@ -43,9 +43,9 @@ And similarly for `Path.open()`:
 from pathlib import Path
 import pickle
 
-reveal_type(Path("").open())  # revealed: @Todo(`Path.open` return type)
-reveal_type(Path("").open("r"))  # revealed: @Todo(`Path.open` return type)
-reveal_type(Path("").open("rb"))  # revealed: @Todo(`Path.open` return type)
+reveal_type(Path("").open())  # revealed: TextIOWrapper[_WrappedBuffer]
+reveal_type(Path("").open("r"))  # revealed: TextIOWrapper[_WrappedBuffer]
+reveal_type(Path("").open("rb"))  # revealed: BufferedReader[_BufferedReaderStream]
 
 with Path("foo.pickle").open("rb") as f:
     x = pickle.load(f)  # fine
@@ -61,7 +61,7 @@ import pickle
 
 reveal_type(NamedTemporaryFile())  # revealed: _TemporaryFileWrapper[bytes]
 reveal_type(NamedTemporaryFile("r"))  # revealed: _TemporaryFileWrapper[str]
-reveal_type(NamedTemporaryFile("rb"))  # revealed: @Todo(`tempfile.NamedTemporaryFile` return type)
+reveal_type(NamedTemporaryFile("rb"))  # revealed: _TemporaryFileWrapper[bytes]
 
 with NamedTemporaryFile("rb") as f:
     x = pickle.load(f)  # fine

crates/ty_python_semantic/resources/mdtest/class/super.md

@@ -501,8 +501,8 @@ class A[T]:
         return a
 
 class B[T](A[T]):
-    def f(self, b: T) -> T:
-        return super().f(b)
+    def f(self, a: T) -> T:
+        return super().f(a)
 ```
 
 ## Invalid Usages

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

@@ -24,10 +24,10 @@ class GtReturnType: ...
 class GeReturnType: ...
 
 class A:
-    def __eq__(self, other: A) -> EqReturnType:
+    def __eq__(self, other: A) -> EqReturnType:  # error: [invalid-method-override]
         return EqReturnType()
 
-    def __ne__(self, other: A) -> NeReturnType:
+    def __ne__(self, other: A) -> NeReturnType:  # error: [invalid-method-override]
         return NeReturnType()
 
     def __lt__(self, other: A) -> LtReturnType:
@@ -66,10 +66,10 @@ class GtReturnType: ...
 class GeReturnType: ...
 
 class A:
-    def __eq__(self, other: B) -> EqReturnType:
+    def __eq__(self, other: B) -> EqReturnType:  # error: [invalid-method-override]
         return EqReturnType()
 
-    def __ne__(self, other: B) -> NeReturnType:
+    def __ne__(self, other: B) -> NeReturnType:  # error: [invalid-method-override]
         return NeReturnType()
 
     def __lt__(self, other: B) -> LtReturnType:
@@ -111,10 +111,10 @@ class GtReturnType: ...
 class GeReturnType: ...
 
 class A:
-    def __eq__(self, other: B) -> EqReturnType:
+    def __eq__(self, other: B) -> EqReturnType:  # error: [invalid-method-override]
         return EqReturnType()
 
-    def __ne__(self, other: B) -> NeReturnType:
+    def __ne__(self, other: B) -> NeReturnType:  # error: [invalid-method-override]
         return NeReturnType()
 
     def __lt__(self, other: B) -> LtReturnType:
@@ -132,12 +132,10 @@ class A:
 class Unrelated: ...
 
 class B:
-    # To override builtins.object.__eq__ and builtins.object.__ne__
-    # TODO these should emit an invalid override diagnostic
-    def __eq__(self, other: Unrelated) -> B:
+    def __eq__(self, other: Unrelated) -> B:  # error: [invalid-method-override]
         return B()
 
-    def __ne__(self, other: Unrelated) -> B:
+    def __ne__(self, other: Unrelated) -> B:  # error: [invalid-method-override]
         return B()
 
 # Because `object.__eq__` and `object.__ne__` accept `object` in typeshed,
@@ -180,10 +178,10 @@ class GtReturnType: ...
 class GeReturnType: ...
 
 class A:
-    def __eq__(self, other: A) -> A:
+    def __eq__(self, other: A) -> A:  # error: [invalid-method-override]
         return A()
 
-    def __ne__(self, other: A) -> A:
+    def __ne__(self, other: A) -> A:  # error: [invalid-method-override]
         return A()
 
     def __lt__(self, other: A) -> A:
@@ -199,22 +197,22 @@ class A:
         return A()
 
 class B(A):
-    def __eq__(self, other: A) -> EqReturnType:
+    def __eq__(self, other: A) -> EqReturnType:  # error: [invalid-method-override]
         return EqReturnType()
 
-    def __ne__(self, other: A) -> NeReturnType:
+    def __ne__(self, other: A) -> NeReturnType:  # error: [invalid-method-override]
         return NeReturnType()
 
-    def __lt__(self, other: A) -> LtReturnType:
+    def __lt__(self, other: A) -> LtReturnType:  # error: [invalid-method-override]
         return LtReturnType()
 
-    def __le__(self, other: A) -> LeReturnType:
+    def __le__(self, other: A) -> LeReturnType:  # error: [invalid-method-override]
         return LeReturnType()
 
-    def __gt__(self, other: A) -> GtReturnType:
+    def __gt__(self, other: A) -> GtReturnType:  # error: [invalid-method-override]
         return GtReturnType()
 
-    def __ge__(self, other: A) -> GeReturnType:
+    def __ge__(self, other: A) -> GeReturnType:  # error: [invalid-method-override]
         return GeReturnType()
 
 reveal_type(A() == B())  # revealed: EqReturnType
@@ -243,10 +241,10 @@ class A:
         return A()
 
 class B(A):
-    def __lt__(self, other: int) -> B:
+    def __lt__(self, other: int) -> B:  # error: [invalid-method-override]
         return B()
 
-    def __gt__(self, other: int) -> B:
+    def __gt__(self, other: int) -> B:  # error: [invalid-method-override]
         return B()
 
 reveal_type(A() < B())  # revealed: A
@@ -291,11 +289,10 @@ Please refer to the [docs](https://docs.python.org/3/reference/datamodel.html#ob
 from __future__ import annotations
 
 class A:
-    # TODO both these overrides should emit invalid-override diagnostic
-    def __eq__(self, other: int) -> A:
+    def __eq__(self, other: int) -> A:  # error: [invalid-method-override]
         return A()
 
-    def __ne__(self, other: int) -> A:
+    def __ne__(self, other: int) -> A:  # error: [invalid-method-override]
         return A()
 
 reveal_type(A() == A())  # revealed: bool

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

@@ -155,10 +155,10 @@ class GtReturnType: ...
 class GeReturnType: ...
 
 class A:
-    def __eq__(self, o: object) -> EqReturnType:
+    def __eq__(self, o: object) -> EqReturnType:  # error: [invalid-method-override]
         return EqReturnType()
 
-    def __ne__(self, o: object) -> NeReturnType:
+    def __ne__(self, o: object) -> NeReturnType:  # error: [invalid-method-override]
         return NeReturnType()
 
     def __lt__(self, o: A) -> LtReturnType:
@@ -386,6 +386,7 @@ class NotBoolable:
     __bool__: None = None
 
 class A:
+    # error: [invalid-method-override]
     def __eq__(self, other) -> NotBoolable:
         return NotBoolable()
 

crates/ty_python_semantic/resources/mdtest/diagnostics/same_names.md

@@ -265,7 +265,7 @@ import dict_a
 import dict_b
 
 def _(b_person: dict_b.Person):
-    # TODO should be error: [invalid-assignment] "Object of type `dict_b.Person` is not assignable to `dict_a.Person`"
+    # error: [invalid-assignment] "Object of type `dict_b.Person` is not assignable to `dict_a.Person`"
     person_var: dict_a.Person = b_person
 ```
 

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

@@ -127,7 +127,7 @@ x = lambda y: y
 reveal_type(x.__code__)  # revealed: CodeType
 reveal_type(x.__name__)  # revealed: str
 reveal_type(x.__defaults__)  # revealed: tuple[Any, ...] | None
-reveal_type(x.__annotations__)  # revealed: dict[str, @Todo(Support for `typing.TypeAlias`)]
+reveal_type(x.__annotations__)  # revealed: dict[str, Any]
 reveal_type(x.__dict__)  # revealed: dict[str, Any]
 reveal_type(x.__doc__)  # revealed: str | None
 reveal_type(x.__kwdefaults__)  # revealed: dict[str, Any] | None

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

@@ -103,8 +103,7 @@ class UnknownLengthSubclassWithDunderLenOverridden(tuple[int, ...]):
 reveal_type(len(UnknownLengthSubclassWithDunderLenOverridden()))  # revealed: Literal[42]
 
 class FixedLengthSubclassWithDunderLenOverridden(tuple[int]):
-    # TODO: we should complain about this as a Liskov violation (incompatible override)
-    def __len__(self) -> Literal[42]:
+    def __len__(self) -> Literal[42]:  # error: [invalid-method-override]
         return 42
 
 reveal_type(len(FixedLengthSubclassWithDunderLenOverridden((1,))))  # revealed: Literal[42]

crates/ty_python_semantic/resources/mdtest/generics/pep695/variables.md

@@ -137,84 +137,26 @@ class Sub(Base): ...
 class Unrelated: ...
 
 def unbounded_unconstrained[T, U](t: T, u: U) -> None:
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, T))
     static_assert(is_assignable_to(T, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, object))
     static_assert(is_assignable_to(T, object))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, Super))
     static_assert(not is_assignable_to(T, Super))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Any))
     static_assert(is_assignable_to(T, Any))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Any, T))
     static_assert(is_assignable_to(Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(U, U))
     static_assert(is_assignable_to(U, U))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(U, object))
     static_assert(is_assignable_to(U, object))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(U, Super))
     static_assert(not is_assignable_to(U, Super))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, U))
     static_assert(not is_assignable_to(T, U))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(U, T))
     static_assert(not is_assignable_to(U, T))
 
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(T, T))
     static_assert(is_subtype_of(T, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(T, object))
     static_assert(is_subtype_of(T, object))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Super))
     static_assert(not is_subtype_of(T, Super))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Any))
     static_assert(not is_subtype_of(T, Any))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Any, T))
     static_assert(not is_subtype_of(Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(U, U))
     static_assert(is_subtype_of(U, U))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(U, object))
     static_assert(is_subtype_of(U, object))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(U, Super))
     static_assert(not is_subtype_of(U, Super))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, U))
     static_assert(not is_subtype_of(T, U))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(U, T))
     static_assert(not is_subtype_of(U, T))
 ```
 
@@ -229,137 +171,47 @@ from typing import Any
 from typing_extensions import final
 
 def bounded[T: Super](t: T) -> None:
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Any))
     static_assert(is_assignable_to(T, Any))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Any, T))
     static_assert(is_assignable_to(Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Super))
     static_assert(is_assignable_to(T, Super))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, Sub))
     static_assert(not is_assignable_to(T, Sub))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(Super, T))
     static_assert(not is_assignable_to(Super, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(Sub, T))
     static_assert(not is_assignable_to(Sub, T))
 
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Any))
     static_assert(not is_subtype_of(T, Any))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Any, T))
     static_assert(not is_subtype_of(Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(T, Super))
     static_assert(is_subtype_of(T, Super))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Sub))
     static_assert(not is_subtype_of(T, Sub))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Super, T))
     static_assert(not is_subtype_of(Super, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Sub, T))
     static_assert(not is_subtype_of(Sub, T))
 
 def bounded_by_gradual[T: Any](t: T) -> None:
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Any))
     static_assert(is_assignable_to(T, Any))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Any, T))
     static_assert(is_assignable_to(Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Super))
     static_assert(is_assignable_to(T, Super))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(Super, T))
     static_assert(not is_assignable_to(Super, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Sub))
     static_assert(is_assignable_to(T, Sub))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(Sub, T))
     static_assert(not is_assignable_to(Sub, T))
 
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Any))
     static_assert(not is_subtype_of(T, Any))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Any, T))
     static_assert(not is_subtype_of(Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Super))
     static_assert(not is_subtype_of(T, Super))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Super, T))
     static_assert(not is_subtype_of(Super, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Sub))
     static_assert(not is_subtype_of(T, Sub))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Sub, T))
     static_assert(not is_subtype_of(Sub, T))
 
 @final
 class FinalClass: ...
 
 def bounded_final[T: FinalClass](t: T) -> None:
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Any))
     static_assert(is_assignable_to(T, Any))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Any, T))
     static_assert(is_assignable_to(Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, FinalClass))
     static_assert(is_assignable_to(T, FinalClass))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(FinalClass, T))
     static_assert(not is_assignable_to(FinalClass, T))
 
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Any))
     static_assert(not is_subtype_of(T, Any))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Any, T))
     static_assert(not is_subtype_of(Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(T, FinalClass))
     static_assert(is_subtype_of(T, FinalClass))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(FinalClass, T))
     static_assert(not is_subtype_of(FinalClass, T))
 ```
 
@@ -370,37 +222,17 @@ typevars to `Never` in addition to that final class.
 
 ```py
 def two_bounded[T: Super, U: Super](t: T, u: U) -> None:
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, U))
     static_assert(not is_assignable_to(T, U))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(U, T))
     static_assert(not is_assignable_to(U, T))
 
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, U))
     static_assert(not is_subtype_of(T, U))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(U, T))
     static_assert(not is_subtype_of(U, T))
 
 def two_final_bounded[T: FinalClass, U: FinalClass](t: T, u: U) -> None:
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, U))
     static_assert(not is_assignable_to(T, U))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(U, T))
     static_assert(not is_assignable_to(U, T))
 
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, U))
     static_assert(not is_subtype_of(T, U))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(U, T))
     static_assert(not is_subtype_of(U, T))
 ```
 
@@ -412,237 +244,67 @@ intersection of all of its constraints is a subtype of the typevar.
 from ty_extensions import Intersection
 
 def constrained[T: (Base, Unrelated)](t: T) -> None:
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, Super))
     static_assert(not is_assignable_to(T, Super))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, Base))
     static_assert(not is_assignable_to(T, Base))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, Sub))
     static_assert(not is_assignable_to(T, Sub))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, Unrelated))
     static_assert(not is_assignable_to(T, Unrelated))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Any))
     static_assert(is_assignable_to(T, Any))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Super | Unrelated))
     static_assert(is_assignable_to(T, Super | Unrelated))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Base | Unrelated))
     static_assert(is_assignable_to(T, Base | Unrelated))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, Sub | Unrelated))
     static_assert(not is_assignable_to(T, Sub | Unrelated))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Any, T))
     static_assert(is_assignable_to(Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(Super, T))
     static_assert(not is_assignable_to(Super, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(Unrelated, T))
     static_assert(not is_assignable_to(Unrelated, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(Super | Unrelated, T))
     static_assert(not is_assignable_to(Super | Unrelated, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Intersection[Base, Unrelated], T))
     static_assert(is_assignable_to(Intersection[Base, Unrelated], T))
 
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Super))
     static_assert(not is_subtype_of(T, Super))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Base))
     static_assert(not is_subtype_of(T, Base))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Sub))
     static_assert(not is_subtype_of(T, Sub))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Unrelated))
     static_assert(not is_subtype_of(T, Unrelated))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Any))
     static_assert(not is_subtype_of(T, Any))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(T, Super | Unrelated))
     static_assert(is_subtype_of(T, Super | Unrelated))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(T, Base | Unrelated))
     static_assert(is_subtype_of(T, Base | Unrelated))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Sub | Unrelated))
     static_assert(not is_subtype_of(T, Sub | Unrelated))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Any, T))
     static_assert(not is_subtype_of(Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Super, T))
     static_assert(not is_subtype_of(Super, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Unrelated, T))
     static_assert(not is_subtype_of(Unrelated, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Super | Unrelated, T))
     static_assert(not is_subtype_of(Super | Unrelated, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(Intersection[Base, Unrelated], T))
     static_assert(is_subtype_of(Intersection[Base, Unrelated], T))
 
 def constrained_by_gradual[T: (Base, Any)](t: T) -> None:
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Super))
     static_assert(is_assignable_to(T, Super))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Base))
     static_assert(is_assignable_to(T, Base))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, Sub))
     static_assert(not is_assignable_to(T, Sub))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, Unrelated))
     static_assert(not is_assignable_to(T, Unrelated))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Any))
     static_assert(is_assignable_to(T, Any))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Super | Any))
     static_assert(is_assignable_to(T, Super | Any))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, Super | Unrelated))
     static_assert(is_assignable_to(T, Super | Unrelated))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(Super, T))
     static_assert(not is_assignable_to(Super, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Base, T))
     static_assert(is_assignable_to(Base, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(Unrelated, T))
     static_assert(not is_assignable_to(Unrelated, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Any, T))
     static_assert(is_assignable_to(Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(Super | Any, T))
     static_assert(not is_assignable_to(Super | Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Base | Any, T))
     static_assert(is_assignable_to(Base | Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(Super | Unrelated, T))
     static_assert(not is_assignable_to(Super | Unrelated, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Intersection[Base, Unrelated], T))
     static_assert(is_assignable_to(Intersection[Base, Unrelated], T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Intersection[Base, Any], T))
     static_assert(is_assignable_to(Intersection[Base, Any], T))
 
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Super))
     static_assert(not is_subtype_of(T, Super))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Base))
     static_assert(not is_subtype_of(T, Base))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Sub))
     static_assert(not is_subtype_of(T, Sub))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Unrelated))
     static_assert(not is_subtype_of(T, Unrelated))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Any))
     static_assert(not is_subtype_of(T, Any))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Super | Any))
     static_assert(not is_subtype_of(T, Super | Any))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, Super | Unrelated))
     static_assert(not is_subtype_of(T, Super | Unrelated))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Super, T))
     static_assert(not is_subtype_of(Super, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Base, T))
     static_assert(not is_subtype_of(Base, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Unrelated, T))
     static_assert(not is_subtype_of(Unrelated, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Any, T))
     static_assert(not is_subtype_of(Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Super | Any, T))
     static_assert(not is_subtype_of(Super | Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Base | Any, T))
     static_assert(not is_subtype_of(Base | Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Super | Unrelated, T))
     static_assert(not is_subtype_of(Super | Unrelated, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Intersection[Base, Unrelated], T))
     static_assert(not is_subtype_of(Intersection[Base, Unrelated], T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(Intersection[Base, Any], T))
     static_assert(not is_subtype_of(Intersection[Base, Any], T))
 ```
 
@@ -653,40 +315,20 @@ the same type.
 
 ```py
 def two_constrained[T: (int, str), U: (int, str)](t: T, u: U) -> None:
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, U))
     static_assert(not is_assignable_to(T, U))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(U, T))
     static_assert(not is_assignable_to(U, T))
 
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, U))
     static_assert(not is_subtype_of(T, U))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(U, T))
     static_assert(not is_subtype_of(U, T))
 
 @final
 class AnotherFinalClass: ...
 
 def two_final_constrained[T: (FinalClass, AnotherFinalClass), U: (FinalClass, AnotherFinalClass)](t: T, u: U) -> None:
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(T, U))
     static_assert(not is_assignable_to(T, U))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_assignable_to(U, T))
     static_assert(not is_assignable_to(U, T))
 
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T, U))
     static_assert(not is_subtype_of(T, U))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(U, T))
     static_assert(not is_subtype_of(U, T))
 ```
 
@@ -694,20 +336,10 @@ A bound or constrained typevar is a subtype of itself in a union:
 
 ```py
 def union[T: Base, U: (Base, Unrelated)](t: T, u: U) -> None:
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T, T | None))
     static_assert(is_assignable_to(T, T | None))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(U, U | None))
     static_assert(is_assignable_to(U, U | None))
 
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(T, T | None))
     static_assert(is_subtype_of(T, T | None))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(U, U | None))
     static_assert(is_subtype_of(U, U | None))
 ```
 
@@ -715,20 +347,10 @@ A bound or constrained typevar in a union with a dynamic type is assignable to t
 
 ```py
 def union_with_dynamic[T: Base, U: (Base, Unrelated)](t: T, u: U) -> None:
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(T | Any, T))
     static_assert(is_assignable_to(T | Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(U | Any, U))
     static_assert(is_assignable_to(U | Any, U))
 
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(T | Any, T))
     static_assert(not is_subtype_of(T | Any, T))
-
-    # revealed: ty_extensions.ConstraintSet[never]
-    reveal_type(is_subtype_of(U | Any, U))
     static_assert(not is_subtype_of(U | Any, U))
 ```
 
@@ -740,20 +362,9 @@ from ty_extensions import Intersection, Not, is_disjoint_from
 class A: ...
 
 def inter[T: Base, U: (Base, Unrelated)](t: T, u: U) -> None:
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Intersection[T, Unrelated], T))
     static_assert(is_assignable_to(Intersection[T, Unrelated], T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(Intersection[T, Unrelated], T))
     static_assert(is_subtype_of(Intersection[T, Unrelated], T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Intersection[U, A], U))
     static_assert(is_assignable_to(Intersection[U, A], U))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(Intersection[U, A], U))
     static_assert(is_subtype_of(Intersection[U, A], U))
 
     static_assert(is_disjoint_from(Not[T], T))
@@ -1054,20 +665,10 @@ of) itself.
 from ty_extensions import is_assignable_to, is_subtype_of, Not, static_assert
 
 def intersection_is_assignable[T](t: T) -> None:
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Intersection[T, None], T))
     static_assert(is_assignable_to(Intersection[T, None], T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_assignable_to(Intersection[T, Not[None]], T))
     static_assert(is_assignable_to(Intersection[T, Not[None]], T))
 
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(Intersection[T, None], T))
     static_assert(is_subtype_of(Intersection[T, None], T))
-
-    # revealed: ty_extensions.ConstraintSet[always]
-    reveal_type(is_subtype_of(Intersection[T, Not[None]], T))
     static_assert(is_subtype_of(Intersection[T, Not[None]], T))
 ```
 

crates/ty_python_semantic/resources/mdtest/implicit_type_aliases.md

@@ -191,13 +191,13 @@ def _(
     reveal_type(int_or_callable)  # revealed: int | ((str, /) -> bytes)
     reveal_type(callable_or_int)  # revealed: ((str, /) -> bytes) | int
     # TODO should be Unknown | int
-    reveal_type(type_var_or_int)  # revealed: T@_ | int
+    reveal_type(type_var_or_int)  # revealed: typing.TypeVar | int
     # TODO should be int | Unknown
-    reveal_type(int_or_type_var)  # revealed: int | T@_
+    reveal_type(int_or_type_var)  # revealed: int | typing.TypeVar
     # TODO should be Unknown | None
-    reveal_type(type_var_or_none)  # revealed: T@_ | None
+    reveal_type(type_var_or_none)  # revealed: typing.TypeVar | None
     # TODO should be None | Unknown
-    reveal_type(none_or_type_var)  # revealed: None | T@_
+    reveal_type(none_or_type_var)  # revealed: None | typing.TypeVar
 ```
 
 If a type is unioned with itself in a value expression, the result is just that type. No
@@ -1109,7 +1109,7 @@ from typing import List, Dict
 # error: [invalid-type-form] "Int literals are not allowed in this context in a type expression"
 InvalidList = List[1]
 
-# error: [invalid-type-form] "`typing.typing.List` requires exactly one argument"
+# error: [invalid-type-form] "`typing.List` requires exactly one argument"
 ListTooManyArgs = List[int, str]
 
 # error: [invalid-type-form] "Int literals are not allowed in this context in a type expression"
@@ -1118,10 +1118,10 @@ InvalidDict1 = Dict[1, str]
 # error: [invalid-type-form] "Int literals are not allowed in this context in a type expression"
 InvalidDict2 = Dict[str, 2]
 
-# error: [invalid-type-form] "`typing.typing.Dict` requires exactly two arguments, got 1"
+# error: [invalid-type-form] "`typing.Dict` requires exactly two arguments, got 1"
 DictTooFewArgs = Dict[str]
 
-# error: [invalid-type-form] "`typing.typing.Dict` requires exactly two arguments, got 3"
+# error: [invalid-type-form] "`typing.Dict` requires exactly two arguments, got 3"
 DictTooManyArgs = Dict[str, int, float]
 
 def _(

crates/ty_python_semantic/resources/mdtest/import/nonstandard_conventions.md

@@ -60,8 +60,8 @@ Y: int = 47
 import mypackage
 
 reveal_type(mypackage.imported.X)  # revealed: int
-# error: "has no member `fails`"
-reveal_type(mypackage.fails.Y)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `fails` may not be available"
+reveal_type(mypackage.fails.Y)  # revealed: int
 ```
 
 ### In Non-Stub
@@ -90,8 +90,8 @@ Y: int = 47
 import mypackage
 
 reveal_type(mypackage.imported.X)  # revealed: int
-# error: "has no member `fails`"
-reveal_type(mypackage.fails.Y)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `fails` may not be available"
+reveal_type(mypackage.fails.Y)  # revealed: int
 ```
 
 ## Absolute `from` Import of Direct Submodule in `__init__`
@@ -125,8 +125,8 @@ Y: int = 47
 import mypackage
 
 reveal_type(mypackage.imported.X)  # revealed: int
-# error: "has no member `fails`"
-reveal_type(mypackage.fails.Y)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `fails` may not be available"
+reveal_type(mypackage.fails.Y)  # revealed: int
 ```
 
 ### In Non-Stub
@@ -155,8 +155,8 @@ Y: int = 47
 import mypackage
 
 reveal_type(mypackage.imported.X)  # revealed: int
-# error: "has no member `fails`"
-reveal_type(mypackage.fails.Y)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `fails` may not be available"
+reveal_type(mypackage.fails.Y)  # revealed: int
 ```
 
 ## Import of Direct Submodule in `__init__`
@@ -184,8 +184,8 @@ X: int = 42
 import mypackage
 
 # TODO: this could work and would be nice to have?
-# error: "has no member `imported`"
-reveal_type(mypackage.imported.X)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `imported` may not be available"
+reveal_type(mypackage.imported.X)  # revealed: int
 ```
 
 ### In Non-Stub
@@ -208,14 +208,14 @@ X: int = 42
 import mypackage
 
 # TODO: this could work and would be nice to have
-# error: "has no member `imported`"
-reveal_type(mypackage.imported.X)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `imported` may not be available"
+reveal_type(mypackage.imported.X)  # revealed: int
 ```
 
 ## Relative `from` Import of Nested Submodule in `__init__`
 
-`from .submodule import nested` in an `__init__.pyi` does not re-export `mypackage.submodule`,
-`mypackage.submodule.nested`, or `nested`.
+`from .submodule import nested` in an `__init__.pyi` does re-export `mypackage.submodule`, but not
+`mypackage.submodule.nested` or `nested`.
 
 ### In Stub
 
@@ -241,15 +241,14 @@ X: int = 42
 ```py
 import mypackage
 
-# error: "has no member `submodule`"
-reveal_type(mypackage.submodule)  # revealed: Unknown
-# error: "has no member `submodule`"
-reveal_type(mypackage.submodule.nested)  # revealed: Unknown
-# error: "has no member `submodule`"
-reveal_type(mypackage.submodule.nested.X)  # revealed: Unknown
-# error: "has no member `nested`"
+reveal_type(mypackage.submodule)  # revealed: <module 'mypackage.submodule'>
+# error: [possibly-missing-attribute] "Submodule `nested` may not be available"
+reveal_type(mypackage.submodule.nested)  # revealed: <module 'mypackage.submodule.nested'>
+# error: [possibly-missing-attribute] "Submodule `nested` may not be available"
+reveal_type(mypackage.submodule.nested.X)  # revealed: int
+# error: [unresolved-attribute] "has no member `nested`"
 reveal_type(mypackage.nested)  # revealed: Unknown
-# error: "has no member `nested`"
+# error: [unresolved-attribute] "has no member `nested`"
 reveal_type(mypackage.nested.X)  # revealed: Unknown
 ```
 
@@ -281,10 +280,10 @@ import mypackage
 
 reveal_type(mypackage.submodule)  # revealed: <module 'mypackage.submodule'>
 # TODO: this would be nice to support
-# error: "has no member `nested`"
-reveal_type(mypackage.submodule.nested)  # revealed: Unknown
-# error: "has no member `nested`"
-reveal_type(mypackage.submodule.nested.X)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `nested` may not be available"
+reveal_type(mypackage.submodule.nested)  # revealed: <module 'mypackage.submodule.nested'>
+# error: [possibly-missing-attribute] "Submodule `nested` may not be available"
+reveal_type(mypackage.submodule.nested.X)  # revealed: int
 reveal_type(mypackage.nested)  # revealed: <module 'mypackage.submodule.nested'>
 reveal_type(mypackage.nested.X)  # revealed: int
 ```
@@ -318,16 +317,14 @@ X: int = 42
 ```py
 import mypackage
 
-# TODO: this could work and would be nice to have
-# error: "has no member `submodule`"
-reveal_type(mypackage.submodule)  # revealed: Unknown
-# error: "has no member `submodule`"
-reveal_type(mypackage.submodule.nested)  # revealed: Unknown
-# error: "has no member `submodule`"
-reveal_type(mypackage.submodule.nested.X)  # revealed: Unknown
-# error: "has no member `nested`"
+reveal_type(mypackage.submodule)  # revealed: <module 'mypackage.submodule'>
+# error: [possibly-missing-attribute] "Submodule `nested` may not be available"
+reveal_type(mypackage.submodule.nested)  # revealed: <module 'mypackage.submodule.nested'>
+# error: [possibly-missing-attribute] "Submodule `nested` may not be available"
+reveal_type(mypackage.submodule.nested.X)  # revealed: int
+# error: [unresolved-attribute] "has no member `nested`"
 reveal_type(mypackage.nested)  # revealed: Unknown
-# error: "has no member `nested`"
+# error: [unresolved-attribute] "has no member `nested`"
 reveal_type(mypackage.nested.X)  # revealed: Unknown
 ```
 
@@ -359,10 +356,10 @@ import mypackage
 
 reveal_type(mypackage.submodule)  # revealed: <module 'mypackage.submodule'>
 # TODO: this would be nice to support
-# error: "has no member `nested`"
-reveal_type(mypackage.submodule.nested)  # revealed: Unknown
-# error: "has no member `nested`"
-reveal_type(mypackage.submodule.nested.X)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `nested` may not be available"
+reveal_type(mypackage.submodule.nested)  # revealed: <module 'mypackage.submodule.nested'>
+# error: [possibly-missing-attribute] "Submodule `nested` may not be available"
+reveal_type(mypackage.submodule.nested.X)  # revealed: int
 reveal_type(mypackage.nested)  # revealed: <module 'mypackage.submodule.nested'>
 reveal_type(mypackage.nested.X)  # revealed: int
 ```
@@ -396,12 +393,14 @@ X: int = 42
 ```py
 import mypackage
 
-# error: "has no member `submodule`"
-reveal_type(mypackage.submodule)  # revealed: Unknown
-# error: "has no member `submodule`"
-reveal_type(mypackage.submodule.nested)  # revealed: Unknown
-# error: "has no member `submodule`"
-reveal_type(mypackage.submodule.nested.X)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `submodule` may not be available"
+reveal_type(mypackage.submodule)  # revealed: <module 'mypackage.submodule'>
+# error: [possibly-missing-attribute] "Submodule `submodule` may not be available"
+# error: [possibly-missing-attribute] "Submodule `nested` may not be available"
+reveal_type(mypackage.submodule.nested)  # revealed: <module 'mypackage.submodule.nested'>
+# error: [possibly-missing-attribute] "Submodule `submodule` may not be available"
+# error: [possibly-missing-attribute] "Submodule `nested` may not be available"
+reveal_type(mypackage.submodule.nested.X)  # revealed: int
 ```
 
 ### In Non-Stub
@@ -432,12 +431,14 @@ X: int = 42
 import mypackage
 
 # TODO: this would be nice to support
-# error: "has no member `submodule`"
-reveal_type(mypackage.submodule)  # revealed: Unknown
-# error: "has no member `submodule`"
-reveal_type(mypackage.submodule.nested)  # revealed: Unknown
-# error: "has no member `submodule`"
-reveal_type(mypackage.submodule.nested.X)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `submodule` may not be available"
+reveal_type(mypackage.submodule)  # revealed: <module 'mypackage.submodule'>
+# error: [possibly-missing-attribute] "Submodule `submodule` may not be available"
+# error: [possibly-missing-attribute] "Submodule `nested` may not be available"
+reveal_type(mypackage.submodule.nested)  # revealed: <module 'mypackage.submodule.nested'>
+# error: [possibly-missing-attribute] "Submodule `submodule` may not be available"
+# error: [possibly-missing-attribute] "Submodule `nested` may not be available"
+reveal_type(mypackage.submodule.nested.X)  # revealed: int
 ```
 
 ## Relative `from` Import of Direct Submodule in `__init__`, Mismatched Alias
@@ -463,9 +464,9 @@ X: int = 42
 ```py
 import mypackage
 
-# error: "has no member `imported`"
-reveal_type(mypackage.imported.X)  # revealed: Unknown
-# error: "has no member `imported_m`"
+# error: [possibly-missing-attribute] "Submodule `imported` may not be available"
+reveal_type(mypackage.imported.X)  # revealed: int
+# error: [unresolved-attribute] "has no member `imported_m`"
 reveal_type(mypackage.imported_m.X)  # revealed: Unknown
 ```
 
@@ -489,8 +490,8 @@ X: int = 42
 import mypackage
 
 # TODO: this would be nice to support, as it works at runtime
-# error: "has no member `imported`"
-reveal_type(mypackage.imported.X)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `imported` may not be available"
+reveal_type(mypackage.imported.X)  # revealed: int
 reveal_type(mypackage.imported_m.X)  # revealed: int
 ```
 
@@ -569,7 +570,7 @@ X: int = 42
 from mypackage import *
 
 # TODO: this would be nice to support
-# error: "`imported` used when not defined"
+# error: [unresolved-reference] "`imported` used when not defined"
 reveal_type(imported.X)  # revealed: Unknown
 reveal_type(Z)  # revealed: int
 ```
@@ -623,8 +624,7 @@ X: int = 42
 ```py
 import mypackage
 
-# error: "no member `imported`"
-reveal_type(mypackage.imported.X)  # revealed: Unknown
+reveal_type(mypackage.imported.X)  # revealed: int
 ```
 
 ### In Non-Stub
@@ -673,11 +673,12 @@ X: int = 42
 import mypackage
 from mypackage import imported
 
+reveal_type(imported.X)  # revealed: int
+
 # TODO: this would be nice to support, but it's dangerous with available_submodule_attributes
 # for details, see: https://github.com/astral-sh/ty/issues/1488
-reveal_type(imported.X)  # revealed: int
-# error: "has no member `imported`"
-reveal_type(mypackage.imported.X)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `imported` may not be available"
+reveal_type(mypackage.imported.X)  # revealed: int
 ```
 
 ### In Non-Stub
@@ -699,10 +700,11 @@ X: int = 42
 import mypackage
 from mypackage import imported
 
-# TODO: this would be nice to support, as it works at runtime
 reveal_type(imported.X)  # revealed: int
-# error: "has no member `imported`"
-reveal_type(mypackage.imported.X)  # revealed: Unknown
+
+# TODO: this would be nice to support, as it works at runtime
+# error: [possibly-missing-attribute] "Submodule `imported` may not be available"
+reveal_type(mypackage.imported.X)  # revealed: int
 ```
 
 ## `from` Import of Sibling Module
@@ -737,10 +739,10 @@ import mypackage
 from mypackage import imported
 
 reveal_type(imported.X)  # revealed: int
-# error: "has no member `fails`"
+# error: [unresolved-attribute] "has no member `fails`"
 reveal_type(imported.fails.Y)  # revealed: Unknown
-# error: "has no member `fails`"
-reveal_type(mypackage.fails.Y)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `fails` may not be available"
+reveal_type(mypackage.fails.Y)  # revealed: int
 ```
 
 ### In Non-Stub
@@ -772,8 +774,8 @@ from mypackage import imported
 
 reveal_type(imported.X)  # revealed: int
 reveal_type(imported.fails.Y)  # revealed: int
-# error: "has no member `fails`"
-reveal_type(mypackage.fails.Y)  # revealed: Unknown
+# error: [possibly-missing-attribute] "Submodule `fails`"
+reveal_type(mypackage.fails.Y)  # revealed: int
 ```
 
 ## Fractal Re-export Nameclash Problems

crates/ty_python_semantic/resources/mdtest/import/relative.md

@@ -247,8 +247,8 @@ X: int = 42
 from . import foo
 import package
 
-# error: [unresolved-attribute] "Module `package` has no member `foo`"
-reveal_type(package.foo.X)  # revealed: Unknown
+# error: [possibly-missing-attribute]
+reveal_type(package.foo.X)  # revealed: int
 ```
 
 ## Relative imports at the top of a search path

crates/ty_python_semantic/resources/mdtest/liskov.md

@@ -0,0 +1,525 @@
+# The Liskov Substitution Principle
+
+The Liskov Substitution Principle provides the basis for many of the assumptions a type checker
+generally makes about types in Python:
+
+> Subtype Requirement: Let ⁠`ϕ(x)`⁠ be a property provable about objects ⁠`x`⁠ of type `T`. Then
+> ⁠`ϕ(y)`⁠ should be true for objects ⁠`y` of type `S` where `S` is a subtype of `T`.
+
+In order for a type checker's assumptions to be sound, it is crucial for the type checker to enforce
+the Liskov Substitution Principle on code that it checks. In practice, this usually manifests as
+several checks for a type checker to perform when it checks a subclass `B` of a class `A`:
+
+1. Read-only attributes should only ever be overridden covariantly: if a property `A.p` resolves to
+    `int` when accessed, accessing `B.p` should either resolve to `int` or a subtype of `int`.
+1. Method return types should only ever be overridden covariantly: if a method `A.f` returns `int`
+    when called, calling `B.f` should also resolve to `int or a subtype of`int\`.
+1. Method parameters should only ever be overridden contravariantly: if a method `A.f` can be called
+    with an argument of type `bool`, then the method `B.f` must also be callable with type `bool`
+    (though it is permitted for the override to also accept other types)
+1. Mutable attributes should only ever be overridden invariantly: if a mutable attribute `A.attr`
+    resolves to type `str`, it can only be overridden on a subclass with exactly the same type.
+
+## Method return types
+
+<!-- snapshot-diagnostics -->
+
+```pyi
+class Super:
+    def method(self) -> int: ...
+
+class Sub1(Super):
+    def method(self) -> int: ...  # fine
+
+class Sub2(Super):
+    def method(self) -> bool: ...  # fine: `bool` is a subtype of `int`
+
+class Sub3(Super):
+    def method(self) -> object: ...  # error: [invalid-method-override]
+
+class Sub4(Super):
+    def method(self) -> str: ...  # error: [invalid-method-override]
+```
+
+## Method parameters
+
+<!-- snapshot-diagnostics -->
+
+```pyi
+class Super:
+    def method(self, x: int, /): ...
+
+class Sub1(Super):
+    def method(self, x: int, /): ...  # fine
+
+class Sub2(Super):
+    def method(self, x: object, /): ...  # fine: `method` still accepts any argument of type `int`
+
+class Sub4(Super):
+    def method(self, x: int | str, /): ...  # fine
+
+class Sub5(Super):
+    def method(self, x: int): ...  # fine: `x` can still be passed positionally
+
+class Sub6(Super):
+    # fine: `method()` can still be called with just a single argument
+    def method(self, x: int, *args): ...
+
+class Sub7(Super):
+    def method(self, x: int, **kwargs): ...  # fine
+
+class Sub8(Super):
+    def method(self, x: int, *args, **kwargs): ...  # fine
+
+class Sub9(Super):
+    def method(self, x: int, extra_positional_arg=42, /): ... # fine
+
+class Sub10(Super):
+    def method(self, x: int, extra_pos_or_kw_arg=42): ...  # fine
+
+class Sub11(Super):
+    def method(self, x: int, *, extra_kw_only_arg=42): ...  # fine
+
+class Sub12(Super):
+    # Some calls permitted by the superclass are now no longer allowed
+    # (the method can no longer be passed any arguments!)
+    def method(self, /): ...  # error: [invalid-method-override]
+
+class Sub13(Super):
+    # Some calls permitted by the superclass are now no longer allowed
+    # (the method can no longer be passed exactly one argument!)
+    def method(self, x, y, /): ...  # error: [invalid-method-override]
+
+class Sub14(Super):
+    # Some calls permitted by the superclass are now no longer allowed
+    # (x can no longer be passed positionally!)
+    def method(self, /, *, x): ...  # error: [invalid-method-override]
+
+class Sub15(Super):
+    # Some calls permitted by the superclass are now no longer allowed
+    # (x can no longer be passed any integer -- it now requires a bool!)
+    def method(self, x: bool, /): ...  # error: [invalid-method-override]
+
+class Super2:
+    def method2(self, x): ...
+
+class Sub16(Super2):
+    def method2(self, x, /): ...  # error: [invalid-method-override]
+
+class Sub17(Super2):
+    def method2(self, *, x): ...  # error: [invalid-method-override]
+
+class Super3:
+    def method3(self, *, x): ...
+
+class Sub18(Super3):
+    def method3(self, x): ...  # fine: `x` can still be used as a keyword argument
+
+class Sub19(Super3):
+    def method3(self, x, /): ...  # error: [invalid-method-override]
+
+class Super4:
+    def method(self, *args: int, **kwargs: str): ...
+
+class Sub20(Super4):
+    def method(self, *args: object, **kwargs: object): ...  # fine
+
+class Sub21(Super4):
+    def method(self, *args): ...  # error: [invalid-method-override]
+
+class Sub22(Super4):
+    def method(self, **kwargs): ...  # error: [invalid-method-override]
+
+class Sub23(Super4):
+    def method(self, x, *args, y, **kwargs): ...  # error: [invalid-method-override]
+```
+
+## The entire class hierarchy is checked
+
+If a child class's method definition is Liskov-compatible with the method definition on its parent
+class, Liskov compatibility must also nonetheless be checked with respect to the method definition
+on its grandparent class. This is because type checkers will treat the child class as a subtype of
+the grandparent class just as much as they treat it as a subtype of the parent class, so
+substitutability with respect to the grandparent class is just as important:
+
+<!-- snapshot-diagnostics -->
+
+`stub.pyi`:
+
+```pyi
+from typing import Any
+
+class Grandparent:
+    def method(self, x: int) -> None: ...
+
+class Parent(Grandparent):
+    def method(self, x: str) -> None: ...  # error: [invalid-method-override]
+
+class Child(Parent):
+    # compatible with the signature of `Parent.method`, but not with `Grandparent.method`:
+    def method(self, x: str) -> None: ...  # error: [invalid-method-override]
+
+class OtherChild(Parent):
+    # compatible with the signature of `Grandparent.method`, but not with `Parent.method`:
+    def method(self, x: int) -> None: ...  # error: [invalid-method-override]
+
+class GradualParent(Grandparent):
+    def method(self, x: Any) -> None: ...
+
+class ThirdChild(GradualParent):
+    # `GradualParent.method` is compatible with the signature of `Grandparent.method`,
+    # and `ThirdChild.method` is compatible with the signature of `GradualParent.method`,
+    # but `ThirdChild.method` is not compatible with the signature of `Grandparent.method`
+    def method(self, x: str) -> None: ...  # error: [invalid-method-override]
+```
+
+`other_stub.pyi`:
+
+```pyi
+class A:
+    def get(self, default): ...
+
+class B(A):
+    def get(self, default, /): ...  # error: [invalid-method-override]
+
+get = 56
+
+class C(B):
+    # `get` appears in the symbol table of `C`,
+    # but that doesn't confuse our diagnostic...
+    foo = get
+
+class D(C):
+    # compatible with `C.get` and `B.get`, but not with `A.get`
+    def get(self, my_default): ...  # error: [invalid-method-override]
+```
+
+## Non-generic methods on generic classes work as expected
+
+```toml
+[environment]
+python-version = "3.12"
+```
+
+```pyi
+class A[T]:
+    def method(self, x: T) -> None: ...
+
+class B[T](A[T]):
+    def method(self, x: T) -> None: ...  # fine
+
+class C(A[int]):
+    def method(self, x: int) -> None: ...  # fine
+
+class D[T](A[T]):
+    def method(self, x: object) -> None: ...  # fine
+
+class E(A[int]):
+    def method(self, x: object) -> None: ...  # fine
+
+class F[T](A[T]):
+    # TODO: we should emit `invalid-method-override` on this:
+    # `str` is not necessarily a supertype of `T`!
+    def method(self, x: str) -> None: ...
+
+class G(A[int]):
+    def method(self, x: bool) -> None: ...  # error: [invalid-method-override]
+```
+
+## Generic methods on non-generic classes work as expected
+
+```toml
+[environment]
+python-version = "3.12"
+```
+
+```pyi
+from typing import Never, Self
+
+class A:
+    def method[T](self, x: T) -> T: ...
+
+class B(A):
+    def method[T](self, x: T) -> T: ...  # fine
+
+class C(A):
+    def method(self, x: object) -> Never: ...  # fine
+
+class D(A):
+    # TODO: we should emit [invalid-method-override] here:
+    # `A.method` accepts an argument of any type,
+    # but `D.method` only accepts `int`s
+    def method(self, x: int) -> int: ...
+
+class A2:
+    def method(self, x: int) -> int: ...
+
+class B2(A2):
+    # fine: although `B2.method()` will not always return an `int`,
+    # an instance of `B2` can be substituted wherever an instance of `A2` is expected,
+    # and it *will* always return an `int` if it is passed an `int`
+    # (which is all that will be allowed if an instance of `A2` is expected)
+    def method[T](self, x: T) -> T: ...
+
+class C2(A2):
+    def method[T: int](self, x: T) -> T: ...
+
+class D2(A2):
+    # The type variable is bound to a type disjoint from `int`,
+    # so the method will not accept integers, and therefore this is an invalid override
+    def method[T: str](self, x: T) -> T: ...  # error: [invalid-method-override]
+
+class A3:
+    def method(self) -> Self: ...
+
+class B3(A3):
+    def method(self) -> Self: ...  # fine
+
+class C3(A3):
+    # TODO: should this be allowed?
+    # Mypy/pyright/pyrefly all allow it,
+    # but conceptually it seems similar to `B4.method` below,
+    # which mypy/pyrefly agree is a Liskov violation
+    # (pyright disagrees as of 20/11/2025: https://github.com/microsoft/pyright/issues/11128)
+    # when called on a subclass, `C3.method()` will not return an
+    # instance of that subclass
+    def method(self) -> C3: ...
+
+class D3(A3):
+    def method(self: Self) -> Self: ...  # fine
+
+class E3(A3):
+    def method(self: E3) -> Self: ...  # fine
+
+class F3(A3):
+    def method(self: A3) -> Self: ...  # fine
+
+class G3(A3):
+    def method(self: object) -> Self: ...  # fine
+
+class H3(A3):
+    # TODO: we should emit `invalid-method-override` here
+    # (`A3.method()` can be called on any instance of `A3`,
+    # but `H3.method()` can only be called on objects that are
+    # instances of `str`)
+    def method(self: str) -> Self: ...
+
+class I3(A3):
+    # TODO: we should emit `invalid-method-override` here
+    # (`I3.method()` cannot be called with any inhabited type!)
+    def method(self: Never) -> Self: ...
+
+class A4:
+    def method[T: int](self, x: T) -> T: ...
+
+class B4(A4):
+    # TODO: we should emit `invalid-method-override` here.
+    # `A4.method` promises that if it is passed a `bool`, it will return a `bool`,
+    # but this is not necessarily true for `B4.method`: if passed a `bool`,
+    # it could return a non-`bool` `int`!
+    def method(self, x: int) -> int: ...
+```
+
+## Generic methods on generic classes work as expected
+
+```toml
+[environment]
+python-version = "3.12"
+```
+
+```pyi
+from typing import Never
+
+class A[T]:
+    def method[S](self, x: T, y: S) -> S: ...
+
+class B[T](A[T]):
+    def method[S](self, x: T, y: S) -> S: ...  # fine
+
+class C(A[int]):
+    def method[S](self, x: int, y: S) -> S: ...  # fine
+
+class D[T](A[T]):
+    def method[S](self, x: object, y: S) -> S: ...  # fine
+
+class E(A[int]):
+    def method[S](self, x: object, y: S) -> S: ...  # fine
+
+class F(A[int]):
+    def method(self, x: object, y: object) -> Never: ...  # fine
+
+class A2[T]:
+    def method(self, x: T, y: int) -> int: ...
+
+class B2[T](A2[T]):
+    def method[S](self, x: T, y: S) -> S: ...  # fine
+```
+
+## Fully qualified names are used in diagnostics where appropriate
+
+<!-- snapshot-diagnostics -->
+
+`a.pyi`:
+
+```pyi
+class A:
+    def foo(self, x): ...
+```
+
+`b.pyi`:
+
+```pyi
+import a
+
+class A(a.A):
+    def foo(self, y): ...  # error: [invalid-method-override]
+```
+
+## Excluded methods
+
+Certain special constructor methods are excluded from Liskov checks. None of the following classes
+cause us to emit any errors, therefore:
+
+```toml
+# This is so that the dataclasses machinery will generate `__replace__` methods for us
+# (the synthesized `__replace__` methods should not be reported as invalid overrides!)
+[environment]
+python-version = "3.13"
+```
+
+```pyi
+from dataclasses import dataclass
+from typing_extensions import Self
+
+class Grandparent: ...
+class Parent(Grandparent):
+    def __new__(cls, x: int) -> Self: ...
+    def __init__(self, x: int) -> None: ...
+
+class Child(Parent):
+    def __new__(cls, x: str, y: str) -> Self: ...
+    def __init__(self, x: str, y: str) -> Self: ...
+
+@dataclass(init=False)
+class DataSuper:
+    x: int
+
+    def __post_init__(self, x: int) -> None:
+        self.x = x
+
+@dataclass(init=False)
+class DataSub(DataSuper):
+    y: str
+
+    def __post_init__(self, x: int, y: str) -> None:
+        self.y = y
+        super().__post_init__(x)
+```
+
+## Edge case: function defined in another module and then assigned in a class body
+
+<!-- snapshot-diagnostics -->
+
+`foo.pyi`:
+
+```pyi
+def x(self, y: str): ...
+```
+
+`bar.pyi`:
+
+```pyi
+import foo
+
+class A:
+    def x(self, y: int): ...
+
+class B(A):
+    x = foo.x  # error: [invalid-method-override]
+
+class C:
+    x = foo.x
+
+class D(C):
+    def x(self, y: int): ...  # error: [invalid-method-override]
+```
+
+## Bad override of `__eq__`
+
+<!-- snapshot-diagnostics -->
+
+```py
+class Bad:
+    x: int
+    def __eq__(self, other: "Bad") -> bool:  # error: [invalid-method-override]
+        return self.x == other.x
+```
+
+## Synthesized methods
+
+`NamedTuple` classes and dataclasses both have methods generated at runtime that do not have
+source-code definitions. There are several scenarios to consider here:
+
+1. A synthesized method on a superclass is overridden by a "normal" (not synthesized) method on a
+    subclass
+1. A "normal" method on a superclass is overridden by a synthesized method on a subclass
+1. A synthesized method on a superclass is overridden by a synthesized method on a subclass
+
+<!-- snapshot-diagnostics -->
+
+```pyi
+from dataclasses import dataclass
+from typing import NamedTuple
+
+@dataclass(order=True)
+class Foo:
+    x: int
+
+class Bar(Foo):
+    def __lt__(self, other: Bar) -> bool: ...  # error: [invalid-method-override]
+
+# TODO: specifying `order=True` on the subclass means that a `__lt__` method is
+# generated that is incompatible with the generated `__lt__` method on the superclass.
+# We could consider detecting this and emitting a diagnostic, though maybe it shouldn't
+# be `invalid-method-override` since we'd emit it on the class definition rather than
+# on any method definition. Note also that no other type checker complains about this
+# as of 2025-11-21.
+@dataclass(order=True)
+class Bar2(Foo):
+    y: str
+
+# TODO: Although this class does not override any methods of `Foo`, the design of the
+# `order=True` stdlib dataclasses feature itself arguably violates the Liskov Substitution
+# Principle! Instances of `Bar3` cannot be substituted wherever an instance of `Foo` is
+# expected, because the generated `__lt__` method on `Foo` raises an error unless the r.h.s.
+# and `l.h.s.` have exactly the same `__class__` (it does not permit instances of `Foo` to
+# be compared with instances of subclasses of `Foo`).
+#
+# Many users would probably like their type checkers to alert them to cases where instances
+# of subclasses cannot be substituted for instances of superclasses, as this violates many
+# assumptions a type checker will make and makes it likely that a type checker will fail to
+# catch type errors elsewhere in the user's code. We could therefore consider treating all
+# `order=True` dataclasses as implicitly `@final` in order to enforce soundness. However,
+# this probably shouldn't be reported with the same error code as Liskov violations, since
+# the error does not stem from any method signatures written by the user. The example is
+# only included here for completeness.
+#
+# Note that no other type checker catches this error as of 2025-11-21.
+class Bar3(Foo): ...
+
+class Eggs:
+    def __lt__(self, other: Eggs) -> bool: ...
+
+# TODO: the generated `Ham.__lt__` method here incompatibly overrides `Eggs.__lt__`.
+# We could consider emitting a diagnostic here. As of 2025-11-21, mypy reports a
+# diagnostic here but pyright and pyrefly do not.
+@dataclass(order=True)
+class Ham(Eggs):
+    x: int
+
+class Baz(NamedTuple):
+    x: int
+
+class Spam(Baz):
+    def _asdict(self) -> tuple[int, ...]: ...  # error: [invalid-method-override]
+```

crates/ty_python_semantic/resources/mdtest/literal_promotion.md

@@ -335,6 +335,9 @@ reveal_type(x19)  # revealed: list[Literal[1]]
 x20: list[Literal[1]] | None = [1]
 reveal_type(x20)  # revealed: list[Literal[1]]
 
-x21: X[Literal[1]] | None = x(1)
+x21: X[Literal[1]] | None = X(1)
 reveal_type(x21)  # revealed: X[Literal[1]]
+
+x22: X[Literal[1]] | None = x(1)
+reveal_type(x22)  # revealed: X[Literal[1]]
 ```

crates/ty_python_semantic/resources/mdtest/narrow/isinstance.md

@@ -147,6 +147,57 @@ def _(x: int | str | bytes):
         reveal_type(x)  # revealed: (int & Unknown) | (str & Unknown) | (bytes & Unknown)
 ```
 
+## `classinfo` is a `types.UnionType`
+
+Python 3.10 added the ability to use `Union[int, str]` as the second argument to `isinstance()`:
+
+```py
+from typing import Union
+
+IntOrStr = Union[int, str]
+
+reveal_type(IntOrStr)  # revealed: types.UnionType
+
+def _(x: int | str | bytes | memoryview | range):
+    if isinstance(x, IntOrStr):
+        reveal_type(x)  # revealed: int | str
+    elif isinstance(x, Union[bytes, memoryview]):
+        reveal_type(x)  # revealed: bytes | memoryview[int]
+    else:
+        reveal_type(x)  # revealed: range
+
+def _(x: int | str | None):
+    if isinstance(x, Union[int, None]):
+        reveal_type(x)  # revealed: int | None
+    else:
+        reveal_type(x)  # revealed: str
+
+ListStrOrInt = Union[list[str], int]
+
+def _(x: dict[int, str] | ListStrOrInt):
+    # TODO: this should ideally be an error
+    if isinstance(x, ListStrOrInt):
+        # TODO: this should not be narrowed
+        reveal_type(x)  # revealed: list[str] | int
+
+    # TODO: this should ideally be an error
+    if isinstance(x, Union[list[str], int]):
+        # TODO: this should not be narrowed
+        reveal_type(x)  # revealed: list[str] | int
+```
+
+## `Optional` as `classinfo`
+
+```py
+from typing import Optional
+
+def _(x: int | str | None):
+    if isinstance(x, Optional[int]):
+        reveal_type(x)  # revealed: int | None
+    else:
+        reveal_type(x)  # revealed: str
+```
+
 ## `classinfo` is a `typing.py` special form
 
 Certain special forms in `typing.py` are aliases to classes elsewhere in the standard library; these
@@ -262,6 +313,23 @@ def _(flag: bool):
         reveal_type(x)  # revealed: Literal[1, "a"]
 ```
 
+## Generic aliases are not supported as second argument
+
+The `classinfo` argument cannot be a generic alias:
+
+```py
+def _(x: list[str] | list[int] | list[bytes]):
+    # TODO: Ideally, this would be an error (requires https://github.com/astral-sh/ty/issues/116)
+    if isinstance(x, list[int]):
+        # No narrowing here:
+        reveal_type(x)  # revealed: list[str] | list[int] | list[bytes]
+
+    # error: [invalid-argument-type] "Invalid second argument to `isinstance`"
+    if isinstance(x, list[int] | list[str]):
+        # No narrowing here:
+        reveal_type(x)  # revealed: list[str] | list[int] | list[bytes]
+```
+
 ## `type[]` types are narrowed as well as class-literal types
 
 ```py

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

@@ -200,6 +200,26 @@ def _(x: type[int | str | bytes]):
         reveal_type(x)  # revealed: (type[int] & Unknown) | (type[str] & Unknown) | (type[bytes] & Unknown)
 ```
 
+## `classinfo` is a `types.UnionType`
+
+Python 3.10 added the ability to use `Union[int, str]` as the second argument to `issubclass()`:
+
+```py
+from typing import Union
+
+IntOrStr = Union[int, str]
+
+reveal_type(IntOrStr)  # revealed: types.UnionType
+
+def f(x: type[int | str | bytes | range]):
+    if issubclass(x, IntOrStr):
+        reveal_type(x)  # revealed: type[int] | type[str]
+    elif issubclass(x, Union[bytes, memoryview]):
+        reveal_type(x)  # revealed: type[bytes]
+    else:
+        reveal_type(x)  # revealed: <class 'range'>
+```
+
 ## Special cases
 
 ### Emit a diagnostic if the first argument is of wrong type

crates/ty_python_semantic/resources/mdtest/pep613_type_aliases.md

@@ -1,8 +1,147 @@
 # PEP 613 type aliases
 
-## No panics
+PEP 613 type aliases are simple assignment statements, annotated with `typing.TypeAlias` to mark
+them as a type alias. At runtime, they behave the same as implicit type aliases. Our support for
+them is currently the same as for implicit type aliases, but we don't reproduce the full
+implicit-type-alias test suite here, just some particularly interesting cases.
 
-We do not fully support PEP 613 type aliases yet. For now, just make sure that we don't panic:
+## Basic
+
+### as `TypeAlias`
+
+```py
+from typing import TypeAlias
+
+IntOrStr: TypeAlias = int | str
+
+def _(x: IntOrStr):
+    reveal_type(x)  # revealed: int | str
+```
+
+### as `typing.TypeAlias`
+
+```py
+import typing
+
+IntOrStr: typing.TypeAlias = int | str
+
+def _(x: IntOrStr):
+    reveal_type(x)  # revealed: int | str
+```
+
+## Can be used as value
+
+Because PEP 613 type aliases are just annotated assignments, they can be used as values, like a
+legacy type expression (and unlike a PEP 695 type alias). We might prefer this wasn't allowed, but
+people do use it.
+
+```py
+from typing import TypeAlias
+
+MyExc: TypeAlias = Exception
+
+try:
+    raise MyExc("error")
+except MyExc as e:
+    reveal_type(e)  # revealed: Exception
+```
+
+## Can inherit from an alias
+
+```py
+from typing import TypeAlias
+from ty_extensions import is_subtype_of, static_assert
+
+MyList: TypeAlias = list["int"]
+
+class Foo(MyList): ...
+
+static_assert(is_subtype_of(Foo, list[int]))
+```
+
+## Cannot inherit from a stringified alias
+
+```py
+from typing import TypeAlias
+
+MyList: TypeAlias = "list[int]"
+
+# error: [invalid-base] "Invalid class base with type `str`"
+class Foo(MyList): ...
+```
+
+## Unknown type in PEP 604 union
+
+If we run into an unknown type in a PEP 604 union in the right-hand side of a PEP 613 type alias, we
+still understand it as a union type, just with an unknown element.
+
+```py
+from typing import TypeAlias
+from nonexistent import unknown_type  # error: [unresolved-import]
+
+MyAlias: TypeAlias = int | unknown_type | str
+
+def _(x: MyAlias):
+    reveal_type(x)  # revealed: int | Unknown | str
+```
+
+## Callable type in union
+
+```py
+from typing import TypeAlias, Callable
+
+MyAlias: TypeAlias = int | Callable[[str], int]
+
+def _(x: MyAlias):
+    reveal_type(x)  # revealed: int | ((str, /) -> int)
+```
+
+## Subscripted generic alias in union
+
+```py
+from typing import TypeAlias, TypeVar
+
+T = TypeVar("T")
+
+Alias1: TypeAlias = list[T] | set[T]
+MyAlias: TypeAlias = int | Alias1[str]
+
+def _(x: MyAlias):
+    # TODO: int | list[str] | set[str]
+    reveal_type(x)  # revealed: int | @Todo(Specialization of union type alias)
+```
+
+## Imported
+
+`alias.py`:
+
+```py
+from typing import TypeAlias
+
+MyAlias: TypeAlias = int | str
+```
+
+`main.py`:
+
+```py
+from alias import MyAlias
+
+def _(x: MyAlias):
+    reveal_type(x)  # revealed: int | str
+```
+
+## String literal in right-hand side
+
+```py
+from typing import TypeAlias
+
+IntOrStr: TypeAlias = "int | str"
+
+def _(x: IntOrStr):
+    reveal_type(x)  # revealed: int | str
+```
+
+## Cyclic
 
 ```py
 from typing import TypeAlias
@@ -18,6 +157,26 @@ def _(rec: RecursiveHomogeneousTuple):
     reveal_type(rec)  # revealed: tuple[Divergent, ...]
 ```
 
+## Conditionally imported on Python < 3.10
+
+```toml
+[environment]
+python-version = "3.9"
+```
+
+```py
+try:
+    # error: [unresolved-import]
+    from typing import TypeAlias
+except ImportError:
+    from typing_extensions import TypeAlias
+
+MyAlias: TypeAlias = int
+
+def _(x: MyAlias):
+    reveal_type(x)  # revealed: int
+```
+
 ## PEP-613 aliases in stubs are deferred
 
 Although the right-hand side of a PEP-613 alias is a value expression, inference of this value is
@@ -46,7 +205,31 @@ f(stub.B())
 
 class Unrelated: ...
 
-# TODO: we should emit `[invalid-argument-type]` here
-# (the alias is a `@Todo` because it's imported from another file)
+# error: [invalid-argument-type]
 f(Unrelated())
 ```
+
+## Invalid position
+
+`typing.TypeAlias` must be used as the sole annotation in an annotated assignment. Use in any other
+context is an error.
+
+```py
+from typing import TypeAlias
+
+# error: [invalid-type-form]
+def _(x: TypeAlias):
+    reveal_type(x)  # revealed: Unknown
+
+# error: [invalid-type-form]
+y: list[TypeAlias] = []
+```
+
+## Right-hand side is required
+
+```py
+from typing import TypeAlias
+
+# error: [invalid-type-form]
+Empty: TypeAlias
+```

crates/ty_python_semantic/resources/mdtest/pep695_type_aliases.md

@@ -28,7 +28,7 @@ def f() -> None:
 ```py
 type IntOrStr = int | str
 
-reveal_type(IntOrStr.__value__)  # revealed: @Todo(Support for `typing.TypeAlias`)
+reveal_type(IntOrStr.__value__)  # revealed: Any
 ```
 
 ## Invalid assignment

crates/ty_python_semantic/resources/mdtest/protocols.md

@@ -2003,6 +2003,7 @@ python-version = "3.12"
 ```
 
 ```py
+from typing import final
 from typing_extensions import TypeVar, Self, Protocol
 from ty_extensions import is_equivalent_to, static_assert, is_assignable_to, is_subtype_of
 
@@ -2094,6 +2095,13 @@ class NominalReturningSelfNotGeneric:
     def g(self) -> "NominalReturningSelfNotGeneric":
         return self
 
+@final
+class Other: ...
+
+class NominalReturningOtherClass:
+    def g(self) -> Other:
+        raise NotImplementedError
+
 # TODO: should pass
 static_assert(is_equivalent_to(LegacyFunctionScoped, NewStyleFunctionScoped))  # error: [static-assert-error]
 
@@ -2112,8 +2120,7 @@ static_assert(not is_assignable_to(NominalLegacy, UsesSelf))
 static_assert(not is_assignable_to(NominalWithSelf, NewStyleFunctionScoped))
 static_assert(not is_assignable_to(NominalWithSelf, LegacyFunctionScoped))
 static_assert(is_assignable_to(NominalWithSelf, UsesSelf))
-# TODO: should pass
-static_assert(is_subtype_of(NominalWithSelf, UsesSelf))  # error: [static-assert-error]
+static_assert(is_subtype_of(NominalWithSelf, UsesSelf))
 
 # TODO: these should pass
 static_assert(not is_assignable_to(NominalNotGeneric, NewStyleFunctionScoped))  # error: [static-assert-error]
@@ -2126,6 +2133,8 @@ static_assert(not is_assignable_to(NominalReturningSelfNotGeneric, LegacyFunctio
 # TODO: should pass
 static_assert(not is_assignable_to(NominalReturningSelfNotGeneric, UsesSelf))  # error: [static-assert-error]
 
+static_assert(not is_assignable_to(NominalReturningOtherClass, UsesSelf))
+
 # These test cases are taken from the typing conformance suite:
 class ShapeProtocolImplicitSelf(Protocol):
     def set_scale(self, scale: float) -> Self: ...
@@ -3069,18 +3078,15 @@ from typing import Protocol
 from ty_extensions import static_assert, is_subtype_of, is_equivalent_to, is_disjoint_from
 
 class HasRepr(Protocol):
-    # TODO: we should emit a diagnostic here complaining about a Liskov violation
-    # (it incompatibly overrides `__repr__` from `object`, a supertype of `HasRepr`)
+    # error: [invalid-method-override]
     def __repr__(self) -> object: ...
 
 class HasReprRecursive(Protocol):
-    # TODO: we should emit a diagnostic here complaining about a Liskov violation
-    # (it incompatibly overrides `__repr__` from `object`, a supertype of `HasReprRecursive`)
+    # error: [invalid-method-override]
     def __repr__(self) -> "HasReprRecursive": ...
 
 class HasReprRecursiveAndFoo(Protocol):
-    # TODO: we should emit a diagnostic here complaining about a Liskov violation
-    # (it incompatibly overrides `__repr__` from `object`, a supertype of `HasReprRecursiveAndFoo`)
+    # error: [invalid-method-override]
     def __repr__(self) -> "HasReprRecursiveAndFoo": ...
     foo: int
 
@@ -3180,6 +3186,33 @@ from ty_extensions import reveal_protocol_interface
 reveal_protocol_interface(Foo)
 ```
 
+## Known panics
+
+### Protocols generic over TypeVars bound to forward references
+
+This test currently panics because the `ClassLiteral::explicit_bases` query fails to converge. See
+issue <https://github.com/astral-sh/ty/issues/1587>.
+
+<!-- expect-panic: execute: too many cycle iterations -->
+
+```py
+from typing import Any, Protocol, TypeVar
+
+T1 = TypeVar("T1", bound="A2[Any]")
+T2 = TypeVar("T2", bound="A1[Any]")
+T3 = TypeVar("T3", bound="B2[Any]")
+T4 = TypeVar("T4", bound="B1[Any]")
+
+class A1(Protocol[T1]):
+    def get_x(self): ...
+
+class A2(Protocol[T2]):
+    def get_y(self): ...
+
+class B1(A1[T3], Protocol[T3]): ...
+class B2(A2[T4], Protocol[T4]): ...
+```
+
 ## TODO
 
 Add tests for:

crates/ty_python_semantic/resources/mdtest/snapshots/assignment_diagnosti…_-_Subscript_assignment…_-_Unknown_key_for_all_…_(8a0f0e8ceccc51b2).snap

@@ -3,7 +3,7 @@ source: crates/ty_test/src/lib.rs
 expression: snapshot
 ---
 ---
-mdtest name: assignment_diagnostics.md - Subscript assignment diagnostics - Unknown key for all elemens of a union
+mdtest name: assignment_diagnostics.md - Subscript assignment diagnostics - Unknown key for all elements of a union
 mdtest path: crates/ty_python_semantic/resources/mdtest/subscript/assignment_diagnostics.md
 ---
 
@@ -16,26 +16,27 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/subscript/assignment_dia
  2 | 
  3 | class Person(TypedDict):
  4 |     name: str
- 5 | 
- 6 | class Animal(TypedDict):
- 7 |     name: str
- 8 |     legs: int
- 9 | 
-10 | def _(being: Person | Animal) -> None:
-11 |     # error: [invalid-key]
+ 5 |     phone_number: str
+ 6 | 
+ 7 | class Animal(TypedDict):
+ 8 |     name: str
+ 9 |     legs: int
+10 | 
+11 | def _(being: Person | Animal) -> None:
 12 |     # error: [invalid-key]
-13 |     being["surname"] = "unknown"
+13 |     # error: [invalid-key]
+14 |     being["surname"] = "unknown"
 ```
 
 # Diagnostics
 
 ```
 error[invalid-key]: Unknown key "surname" for TypedDict `Person`
-  --> src/mdtest_snippet.py:13:5
+  --> src/mdtest_snippet.py:14:5
    |
-11 |     # error: [invalid-key]
 12 |     # error: [invalid-key]
-13 |     being["surname"] = "unknown"
+13 |     # error: [invalid-key]
+14 |     being["surname"] = "unknown"
    |     ----- ^^^^^^^^^ Did you mean "name"?
    |     |
    |     TypedDict `Person` in union type `Person | Animal`
@@ -46,11 +47,11 @@ info: rule `invalid-key` is enabled by default
 
 ```
 error[invalid-key]: Unknown key "surname" for TypedDict `Animal`
-  --> src/mdtest_snippet.py:13:5
+  --> src/mdtest_snippet.py:14:5
    |
-11 |     # error: [invalid-key]
 12 |     # error: [invalid-key]
-13 |     being["surname"] = "unknown"
+13 |     # error: [invalid-key]
+14 |     being["surname"] = "unknown"
    |     ----- ^^^^^^^^^ Did you mean "name"?
    |     |
    |     TypedDict `Animal` in union type `Person | Animal`

crates/ty_python_semantic/resources/mdtest/snapshots/assignment_diagnosti…_-_Subscript_assignment…_-_Unknown_key_for_one_…_(b515711c0a451a86).snap

@@ -16,23 +16,24 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/subscript/assignment_dia
  2 | 
  3 | class Person(TypedDict):
  4 |     name: str
- 5 | 
- 6 | class Animal(TypedDict):
- 7 |     name: str
- 8 |     legs: int
- 9 | 
-10 | def _(being: Person | Animal) -> None:
-11 |     being["legs"] = 4  # error: [invalid-key]
+ 5 |     phone_number: str
+ 6 | 
+ 7 | class Animal(TypedDict):
+ 8 |     name: str
+ 9 |     legs: int
+10 | 
+11 | def _(being: Person | Animal) -> None:
+12 |     being["legs"] = 4  # error: [invalid-key]
 ```
 
 # Diagnostics
 
 ```
 error[invalid-key]: Unknown key "legs" for TypedDict `Person`
-  --> src/mdtest_snippet.py:11:5
+  --> src/mdtest_snippet.py:12:5
    |
-10 | def _(being: Person | Animal) -> None:
-11 |     being["legs"] = 4  # error: [invalid-key]
+11 | def _(being: Person | Animal) -> None:
+12 |     being["legs"] = 4  # error: [invalid-key]
    |     ----- ^^^^^^ Unknown key "legs"
    |     |
    |     TypedDict `Person` in union type `Person | Animal`

crates/ty_python_semantic/resources/mdtest/snapshots/attributes.md_-_Attributes_-_Attributes_of_standa…_(49ba2c9016d64653).snap

@@ -32,7 +32,8 @@ error[unresolved-attribute]: Module `datetime` has no member `UTC`
 5 | # error: [unresolved-attribute]
 6 | reveal_type(datetime.fakenotreal)  # revealed: Unknown
   |
-info: Python 3.10 was assumed when accessing `UTC` because it was specified on the command line
+info: The member may be available on other Python versions or platforms
+info: Python 3.10 was assumed when resolving the `UTC` attribute because it was specified on the command line
 info: rule `unresolved-attribute` is enabled by default
 
 ```

crates/ty_python_semantic/resources/mdtest/snapshots/attributes.md_-_Attributes_-_Unimported_submodule…_(2b6da09ed380b2).snap

@@ -0,0 +1,68 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: attributes.md - Attributes - Unimported submodule incorrectly accessed as attribute
+mdtest path: crates/ty_python_semantic/resources/mdtest/attributes.md
+---
+
+# Python source files
+
+## foo/__init__.py
+
+```
+```
+
+## foo/bar.py
+
+```
+```
+
+## baz/bar.py
+
+```
+```
+
+## main.py
+
+```
+1 | import foo
+2 | import baz
+3 | 
+4 | # error: [possibly-missing-attribute]
+5 | reveal_type(foo.bar)  # revealed: <module 'foo.bar'>
+6 | # error: [possibly-missing-attribute]
+7 | reveal_type(baz.bar)  # revealed: <module 'baz.bar'>
+```
+
+# Diagnostics
+
+```
+warning[possibly-missing-attribute]: Submodule `bar` may not be available as an attribute on module `foo`
+ --> src/main.py:5:13
+  |
+4 | # error: [possibly-missing-attribute]
+5 | reveal_type(foo.bar)  # revealed: <module 'foo.bar'>
+  |             ^^^^^^^
+6 | # error: [possibly-missing-attribute]
+7 | reveal_type(baz.bar)  # revealed: <module 'baz.bar'>
+  |
+help: Consider explicitly importing `foo.bar`
+info: rule `possibly-missing-attribute` is enabled by default
+
+```
+
+```
+warning[possibly-missing-attribute]: Submodule `bar` may not be available as an attribute on module `baz`
+ --> src/main.py:7:13
+  |
+5 | reveal_type(foo.bar)  # revealed: <module 'foo.bar'>
+6 | # error: [possibly-missing-attribute]
+7 | reveal_type(baz.bar)  # revealed: <module 'baz.bar'>
+  |             ^^^^^^^
+  |
+help: Consider explicitly importing `baz.bar`
+info: rule `possibly-missing-attribute` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/liskov.md_-_The_Liskov_Substitut…_-_Bad_override_of_`__e…_(4b336040d5332220).snap

@@ -0,0 +1,52 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: liskov.md - The Liskov Substitution Principle - Bad override of `__eq__`
+mdtest path: crates/ty_python_semantic/resources/mdtest/liskov.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+1 | class Bad:
+2 |     x: int
+3 |     def __eq__(self, other: "Bad") -> bool:  # error: [invalid-method-override]
+4 |         return self.x == other.x
+```
+
+# Diagnostics
+
+```
+error[invalid-method-override]: Invalid override of method `__eq__`
+   --> src/mdtest_snippet.py:3:9
+    |
+  1 | class Bad:
+  2 |     x: int
+  3 |     def __eq__(self, other: "Bad") -> bool:  # error: [invalid-method-override]
+    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `object.__eq__`
+  4 |         return self.x == other.x
+    |
+   ::: stdlib/builtins.pyi:142:9
+    |
+140 |     def __setattr__(self, name: str, value: Any, /) -> None: ...
+141 |     def __delattr__(self, name: str, /) -> None: ...
+142 |     def __eq__(self, value: object, /) -> bool: ...
+    |         -------------------------------------- `object.__eq__` defined here
+143 |     def __ne__(self, value: object, /) -> bool: ...
+144 |     def __str__(self) -> str: ...  # noqa: Y029
+    |
+info: This violates the Liskov Substitution Principle
+help: It is recommended for `__eq__` to work with arbitrary objects, for example:
+help
+help:     def __eq__(self, other: object) -> bool:
+help:         if not isinstance(other, Bad):
+help:             return False
+help:         return <logic to compare two `Bad` instances>
+help
+info: rule `invalid-method-override` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/liskov.md_-_The_Liskov_Substitut…_-_Edge_case___function_…_(c8756a54d1cb8499).snap

@@ -0,0 +1,82 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: liskov.md - The Liskov Substitution Principle - Edge case: function defined in another module and then assigned in a class body
+mdtest path: crates/ty_python_semantic/resources/mdtest/liskov.md
+---
+
+# Python source files
+
+## foo.pyi
+
+```
+1 | def x(self, y: str): ...
+```
+
+## bar.pyi
+
+```
+ 1 | import foo
+ 2 | 
+ 3 | class A:
+ 4 |     def x(self, y: int): ...
+ 5 | 
+ 6 | class B(A):
+ 7 |     x = foo.x  # error: [invalid-method-override]
+ 8 | 
+ 9 | class C:
+10 |     x = foo.x
+11 | 
+12 | class D(C):
+13 |     def x(self, y: int): ...  # error: [invalid-method-override]
+```
+
+# Diagnostics
+
+```
+error[invalid-method-override]: Invalid override of method `x`
+ --> src/bar.pyi:4:9
+  |
+3 | class A:
+4 |     def x(self, y: int): ...
+  |         --------------- `A.x` defined here
+5 |
+6 | class B(A):
+7 |     x = foo.x  # error: [invalid-method-override]
+  |     ^^^^^^^^^ Definition is incompatible with `A.x`
+8 |
+9 | class C:
+  |
+ ::: src/foo.pyi:1:5
+  |
+1 | def x(self, y: str): ...
+  |     --------------- Signature of `B.x`
+  |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `x`
+  --> src/bar.pyi:10:5
+   |
+ 9 | class C:
+10 |     x = foo.x
+   |     --------- `C.x` defined here
+11 |
+12 | class D(C):
+13 |     def x(self, y: int): ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^ Definition is incompatible with `C.x`
+   |
+  ::: src/foo.pyi:1:5
+   |
+ 1 | def x(self, y: str): ...
+   |     --------------- Signature of `C.x`
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/liskov.md_-_The_Liskov_Substitut…_-_Fully_qualified_name…_(8f6f7c5aace58329).snap

@@ -0,0 +1,47 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: liskov.md - The Liskov Substitution Principle - Fully qualified names are used in diagnostics where appropriate
+mdtest path: crates/ty_python_semantic/resources/mdtest/liskov.md
+---
+
+# Python source files
+
+## a.pyi
+
+```
+1 | class A:
+2 |     def foo(self, x): ...
+```
+
+## b.pyi
+
+```
+1 | import a
+2 | 
+3 | class A(a.A):
+4 |     def foo(self, y): ...  # error: [invalid-method-override]
+```
+
+# Diagnostics
+
+```
+error[invalid-method-override]: Invalid override of method `foo`
+ --> src/b.pyi:4:9
+  |
+3 | class A(a.A):
+4 |     def foo(self, y): ...  # error: [invalid-method-override]
+  |         ^^^^^^^^^^^^ Definition is incompatible with `a.A.foo`
+  |
+ ::: src/a.pyi:2:9
+  |
+1 | class A:
+2 |     def foo(self, x): ...
+  |         ------------ `a.A.foo` defined here
+  |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/liskov.md_-_The_Liskov_Substitut…_-_Method_parameters_(d98059266bcc1e13).snap

@@ -0,0 +1,331 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: liskov.md - The Liskov Substitution Principle - Method parameters
+mdtest path: crates/ty_python_semantic/resources/mdtest/liskov.md
+---
+
+# Python source files
+
+## mdtest_snippet.pyi
+
+```
+ 1 | class Super:
+ 2 |     def method(self, x: int, /): ...
+ 3 | 
+ 4 | class Sub1(Super):
+ 5 |     def method(self, x: int, /): ...  # fine
+ 6 | 
+ 7 | class Sub2(Super):
+ 8 |     def method(self, x: object, /): ...  # fine: `method` still accepts any argument of type `int`
+ 9 | 
+10 | class Sub4(Super):
+11 |     def method(self, x: int | str, /): ...  # fine
+12 | 
+13 | class Sub5(Super):
+14 |     def method(self, x: int): ...  # fine: `x` can still be passed positionally
+15 | 
+16 | class Sub6(Super):
+17 |     # fine: `method()` can still be called with just a single argument
+18 |     def method(self, x: int, *args): ...
+19 | 
+20 | class Sub7(Super):
+21 |     def method(self, x: int, **kwargs): ...  # fine
+22 | 
+23 | class Sub8(Super):
+24 |     def method(self, x: int, *args, **kwargs): ...  # fine
+25 | 
+26 | class Sub9(Super):
+27 |     def method(self, x: int, extra_positional_arg=42, /): ... # fine
+28 | 
+29 | class Sub10(Super):
+30 |     def method(self, x: int, extra_pos_or_kw_arg=42): ...  # fine
+31 | 
+32 | class Sub11(Super):
+33 |     def method(self, x: int, *, extra_kw_only_arg=42): ...  # fine
+34 | 
+35 | class Sub12(Super):
+36 |     # Some calls permitted by the superclass are now no longer allowed
+37 |     # (the method can no longer be passed any arguments!)
+38 |     def method(self, /): ...  # error: [invalid-method-override]
+39 | 
+40 | class Sub13(Super):
+41 |     # Some calls permitted by the superclass are now no longer allowed
+42 |     # (the method can no longer be passed exactly one argument!)
+43 |     def method(self, x, y, /): ...  # error: [invalid-method-override]
+44 | 
+45 | class Sub14(Super):
+46 |     # Some calls permitted by the superclass are now no longer allowed
+47 |     # (x can no longer be passed positionally!)
+48 |     def method(self, /, *, x): ...  # error: [invalid-method-override]
+49 | 
+50 | class Sub15(Super):
+51 |     # Some calls permitted by the superclass are now no longer allowed
+52 |     # (x can no longer be passed any integer -- it now requires a bool!)
+53 |     def method(self, x: bool, /): ...  # error: [invalid-method-override]
+54 | 
+55 | class Super2:
+56 |     def method2(self, x): ...
+57 | 
+58 | class Sub16(Super2):
+59 |     def method2(self, x, /): ...  # error: [invalid-method-override]
+60 | 
+61 | class Sub17(Super2):
+62 |     def method2(self, *, x): ...  # error: [invalid-method-override]
+63 | 
+64 | class Super3:
+65 |     def method3(self, *, x): ...
+66 | 
+67 | class Sub18(Super3):
+68 |     def method3(self, x): ...  # fine: `x` can still be used as a keyword argument
+69 | 
+70 | class Sub19(Super3):
+71 |     def method3(self, x, /): ...  # error: [invalid-method-override]
+72 | 
+73 | class Super4:
+74 |     def method(self, *args: int, **kwargs: str): ...
+75 | 
+76 | class Sub20(Super4):
+77 |     def method(self, *args: object, **kwargs: object): ...  # fine
+78 | 
+79 | class Sub21(Super4):
+80 |     def method(self, *args): ...  # error: [invalid-method-override]
+81 | 
+82 | class Sub22(Super4):
+83 |     def method(self, **kwargs): ...  # error: [invalid-method-override]
+84 | 
+85 | class Sub23(Super4):
+86 |     def method(self, x, *args, y, **kwargs): ...  # error: [invalid-method-override]
+```
+
+# Diagnostics
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+  --> src/mdtest_snippet.pyi:38:9
+   |
+36 |     # Some calls permitted by the superclass are now no longer allowed
+37 |     # (the method can no longer be passed any arguments!)
+38 |     def method(self, /): ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^ Definition is incompatible with `Super.method`
+39 |
+40 | class Sub13(Super):
+   |
+  ::: src/mdtest_snippet.pyi:2:9
+   |
+ 1 | class Super:
+ 2 |     def method(self, x: int, /): ...
+   |         ----------------------- `Super.method` defined here
+ 3 |
+ 4 | class Sub1(Super):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+  --> src/mdtest_snippet.pyi:43:9
+   |
+41 |     # Some calls permitted by the superclass are now no longer allowed
+42 |     # (the method can no longer be passed exactly one argument!)
+43 |     def method(self, x, y, /): ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Super.method`
+44 |
+45 | class Sub14(Super):
+   |
+  ::: src/mdtest_snippet.pyi:2:9
+   |
+ 1 | class Super:
+ 2 |     def method(self, x: int, /): ...
+   |         ----------------------- `Super.method` defined here
+ 3 |
+ 4 | class Sub1(Super):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+  --> src/mdtest_snippet.pyi:48:9
+   |
+46 |     # Some calls permitted by the superclass are now no longer allowed
+47 |     # (x can no longer be passed positionally!)
+48 |     def method(self, /, *, x): ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Super.method`
+49 |
+50 | class Sub15(Super):
+   |
+  ::: src/mdtest_snippet.pyi:2:9
+   |
+ 1 | class Super:
+ 2 |     def method(self, x: int, /): ...
+   |         ----------------------- `Super.method` defined here
+ 3 |
+ 4 | class Sub1(Super):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+  --> src/mdtest_snippet.pyi:53:9
+   |
+51 |     # Some calls permitted by the superclass are now no longer allowed
+52 |     # (x can no longer be passed any integer -- it now requires a bool!)
+53 |     def method(self, x: bool, /): ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Super.method`
+54 |
+55 | class Super2:
+   |
+  ::: src/mdtest_snippet.pyi:2:9
+   |
+ 1 | class Super:
+ 2 |     def method(self, x: int, /): ...
+   |         ----------------------- `Super.method` defined here
+ 3 |
+ 4 | class Sub1(Super):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method2`
+  --> src/mdtest_snippet.pyi:56:9
+   |
+55 | class Super2:
+56 |     def method2(self, x): ...
+   |         ---------------- `Super2.method2` defined here
+57 |
+58 | class Sub16(Super2):
+59 |     def method2(self, x, /): ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Super2.method2`
+60 |
+61 | class Sub17(Super2):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method2`
+  --> src/mdtest_snippet.pyi:62:9
+   |
+61 | class Sub17(Super2):
+62 |     def method2(self, *, x): ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Super2.method2`
+63 |
+64 | class Super3:
+   |
+  ::: src/mdtest_snippet.pyi:56:9
+   |
+55 | class Super2:
+56 |     def method2(self, x): ...
+   |         ---------------- `Super2.method2` defined here
+57 |
+58 | class Sub16(Super2):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method3`
+  --> src/mdtest_snippet.pyi:71:9
+   |
+70 | class Sub19(Super3):
+71 |     def method3(self, x, /): ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Super3.method3`
+72 |
+73 | class Super4:
+   |
+  ::: src/mdtest_snippet.pyi:65:9
+   |
+64 | class Super3:
+65 |     def method3(self, *, x): ...
+   |         ------------------- `Super3.method3` defined here
+66 |
+67 | class Sub18(Super3):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+  --> src/mdtest_snippet.pyi:80:9
+   |
+79 | class Sub21(Super4):
+80 |     def method(self, *args): ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Super4.method`
+81 |
+82 | class Sub22(Super4):
+   |
+  ::: src/mdtest_snippet.pyi:74:9
+   |
+73 | class Super4:
+74 |     def method(self, *args: int, **kwargs: str): ...
+   |         --------------------------------------- `Super4.method` defined here
+75 |
+76 | class Sub20(Super4):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+  --> src/mdtest_snippet.pyi:83:9
+   |
+82 | class Sub22(Super4):
+83 |     def method(self, **kwargs): ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Super4.method`
+84 |
+85 | class Sub23(Super4):
+   |
+  ::: src/mdtest_snippet.pyi:74:9
+   |
+73 | class Super4:
+74 |     def method(self, *args: int, **kwargs: str): ...
+   |         --------------------------------------- `Super4.method` defined here
+75 |
+76 | class Sub20(Super4):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+  --> src/mdtest_snippet.pyi:86:9
+   |
+85 | class Sub23(Super4):
+86 |     def method(self, x, *args, y, **kwargs): ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Super4.method`
+   |
+  ::: src/mdtest_snippet.pyi:74:9
+   |
+73 | class Super4:
+74 |     def method(self, *args: int, **kwargs: str): ...
+   |         --------------------------------------- `Super4.method` defined here
+75 |
+76 | class Sub20(Super4):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/liskov.md_-_The_Liskov_Substitut…_-_Method_return_types_(3e0c19bed14cfacd).snap

@@ -0,0 +1,75 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: liskov.md - The Liskov Substitution Principle - Method return types
+mdtest path: crates/ty_python_semantic/resources/mdtest/liskov.md
+---
+
+# Python source files
+
+## mdtest_snippet.pyi
+
+```
+ 1 | class Super:
+ 2 |     def method(self) -> int: ...
+ 3 | 
+ 4 | class Sub1(Super):
+ 5 |     def method(self) -> int: ...  # fine
+ 6 | 
+ 7 | class Sub2(Super):
+ 8 |     def method(self) -> bool: ...  # fine: `bool` is a subtype of `int`
+ 9 | 
+10 | class Sub3(Super):
+11 |     def method(self) -> object: ...  # error: [invalid-method-override]
+12 | 
+13 | class Sub4(Super):
+14 |     def method(self) -> str: ...  # error: [invalid-method-override]
+```
+
+# Diagnostics
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+  --> src/mdtest_snippet.pyi:11:9
+   |
+10 | class Sub3(Super):
+11 |     def method(self) -> object: ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Super.method`
+12 |
+13 | class Sub4(Super):
+   |
+  ::: src/mdtest_snippet.pyi:2:9
+   |
+ 1 | class Super:
+ 2 |     def method(self) -> int: ...
+   |         ------------------- `Super.method` defined here
+ 3 |
+ 4 | class Sub1(Super):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+  --> src/mdtest_snippet.pyi:14:9
+   |
+13 | class Sub4(Super):
+14 |     def method(self) -> str: ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Super.method`
+   |
+  ::: src/mdtest_snippet.pyi:2:9
+   |
+ 1 | class Super:
+ 2 |     def method(self) -> int: ...
+   |         ------------------- `Super.method` defined here
+ 3 |
+ 4 | class Sub1(Super):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/liskov.md_-_The_Liskov_Substitut…_-_Synthesized_methods_(9e6e6c7368530460).snap

@@ -0,0 +1,116 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: liskov.md - The Liskov Substitution Principle - Synthesized methods
+mdtest path: crates/ty_python_semantic/resources/mdtest/liskov.md
+---
+
+# Python source files
+
+## mdtest_snippet.pyi
+
+```
+ 1 | from dataclasses import dataclass
+ 2 | from typing import NamedTuple
+ 3 | 
+ 4 | @dataclass(order=True)
+ 5 | class Foo:
+ 6 |     x: int
+ 7 | 
+ 8 | class Bar(Foo):
+ 9 |     def __lt__(self, other: Bar) -> bool: ...  # error: [invalid-method-override]
+10 | 
+11 | # TODO: specifying `order=True` on the subclass means that a `__lt__` method is
+12 | # generated that is incompatible with the generated `__lt__` method on the superclass.
+13 | # We could consider detecting this and emitting a diagnostic, though maybe it shouldn't
+14 | # be `invalid-method-override` since we'd emit it on the class definition rather than
+15 | # on any method definition. Note also that no other type checker complains about this
+16 | # as of 2025-11-21.
+17 | @dataclass(order=True)
+18 | class Bar2(Foo):
+19 |     y: str
+20 | 
+21 | # TODO: Although this class does not override any methods of `Foo`, the design of the
+22 | # `order=True` stdlib dataclasses feature itself arguably violates the Liskov Substitution
+23 | # Principle! Instances of `Bar3` cannot be substituted wherever an instance of `Foo` is
+24 | # expected, because the generated `__lt__` method on `Foo` raises an error unless the r.h.s.
+25 | # and `l.h.s.` have exactly the same `__class__` (it does not permit instances of `Foo` to
+26 | # be compared with instances of subclasses of `Foo`).
+27 | #
+28 | # Many users would probably like their type checkers to alert them to cases where instances
+29 | # of subclasses cannot be substituted for instances of superclasses, as this violates many
+30 | # assumptions a type checker will make and makes it likely that a type checker will fail to
+31 | # catch type errors elsewhere in the user's code. We could therefore consider treating all
+32 | # `order=True` dataclasses as implicitly `@final` in order to enforce soundness. However,
+33 | # this probably shouldn't be reported with the same error code as Liskov violations, since
+34 | # the error does not stem from any method signatures written by the user. The example is
+35 | # only included here for completeness.
+36 | #
+37 | # Note that no other type checker catches this error as of 2025-11-21.
+38 | class Bar3(Foo): ...
+39 | 
+40 | class Eggs:
+41 |     def __lt__(self, other: Eggs) -> bool: ...
+42 | 
+43 | # TODO: the generated `Ham.__lt__` method here incompatibly overrides `Eggs.__lt__`.
+44 | # We could consider emitting a diagnostic here. As of 2025-11-21, mypy reports a
+45 | # diagnostic here but pyright and pyrefly do not.
+46 | @dataclass(order=True)
+47 | class Ham(Eggs):
+48 |     x: int
+49 | 
+50 | class Baz(NamedTuple):
+51 |     x: int
+52 | 
+53 | class Spam(Baz):
+54 |     def _asdict(self) -> tuple[int, ...]: ...  # error: [invalid-method-override]
+```
+
+# Diagnostics
+
+```
+error[invalid-method-override]: Invalid override of method `__lt__`
+  --> src/mdtest_snippet.pyi:9:9
+   |
+ 8 | class Bar(Foo):
+ 9 |     def __lt__(self, other: Bar) -> bool: ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Foo.__lt__`
+10 |
+11 | # TODO: specifying `order=True` on the subclass means that a `__lt__` method is
+   |
+info: This violates the Liskov Substitution Principle
+info: `Foo.__lt__` is a generated method created because `Foo` is a dataclass
+ --> src/mdtest_snippet.pyi:5:7
+  |
+4 | @dataclass(order=True)
+5 | class Foo:
+  |       ^^^ Definition of `Foo`
+6 |     x: int
+  |
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `_asdict`
+  --> src/mdtest_snippet.pyi:54:9
+   |
+53 | class Spam(Baz):
+54 |     def _asdict(self) -> tuple[int, ...]: ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Baz._asdict`
+   |
+info: This violates the Liskov Substitution Principle
+info: `Baz._asdict` is a generated method created because `Baz` inherits from `typing.NamedTuple`
+  --> src/mdtest_snippet.pyi:50:7
+   |
+48 |     x: int
+49 |
+50 | class Baz(NamedTuple):
+   |       ^^^^^^^^^^^^^^^ Definition of `Baz`
+51 |     x: int
+   |
+info: rule `invalid-method-override` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/liskov.md_-_The_Liskov_Substitut…_-_The_entire_class_hie…_(5e8fca10d966c36e).snap

@@ -0,0 +1,192 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: liskov.md - The Liskov Substitution Principle - The entire class hierarchy is checked
+mdtest path: crates/ty_python_semantic/resources/mdtest/liskov.md
+---
+
+# Python source files
+
+## stub.pyi
+
+```
+ 1 | from typing import Any
+ 2 | 
+ 3 | class Grandparent:
+ 4 |     def method(self, x: int) -> None: ...
+ 5 | 
+ 6 | class Parent(Grandparent):
+ 7 |     def method(self, x: str) -> None: ...  # error: [invalid-method-override]
+ 8 | 
+ 9 | class Child(Parent):
+10 |     # compatible with the signature of `Parent.method`, but not with `Grandparent.method`:
+11 |     def method(self, x: str) -> None: ...  # error: [invalid-method-override]
+12 | 
+13 | class OtherChild(Parent):
+14 |     # compatible with the signature of `Grandparent.method`, but not with `Parent.method`:
+15 |     def method(self, x: int) -> None: ...  # error: [invalid-method-override]
+16 | 
+17 | class GradualParent(Grandparent):
+18 |     def method(self, x: Any) -> None: ...
+19 | 
+20 | class ThirdChild(GradualParent):
+21 |     # `GradualParent.method` is compatible with the signature of `Grandparent.method`,
+22 |     # and `ThirdChild.method` is compatible with the signature of `GradualParent.method`,
+23 |     # but `ThirdChild.method` is not compatible with the signature of `Grandparent.method`
+24 |     def method(self, x: str) -> None: ...  # error: [invalid-method-override]
+```
+
+## other_stub.pyi
+
+```
+ 1 | class A:
+ 2 |     def get(self, default): ...
+ 3 | 
+ 4 | class B(A):
+ 5 |     def get(self, default, /): ...  # error: [invalid-method-override]
+ 6 | 
+ 7 | get = 56
+ 8 | 
+ 9 | class C(B):
+10 |     # `get` appears in the symbol table of `C`,
+11 |     # but that doesn't confuse our diagnostic...
+12 |     foo = get
+13 | 
+14 | class D(C):
+15 |     # compatible with `C.get` and `B.get`, but not with `A.get`
+16 |     def get(self, my_default): ...  # error: [invalid-method-override]
+```
+
+# Diagnostics
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+ --> src/stub.pyi:4:9
+  |
+3 | class Grandparent:
+4 |     def method(self, x: int) -> None: ...
+  |         ---------------------------- `Grandparent.method` defined here
+5 |
+6 | class Parent(Grandparent):
+7 |     def method(self, x: str) -> None: ...  # error: [invalid-method-override]
+  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Grandparent.method`
+8 |
+9 | class Child(Parent):
+  |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+  --> src/stub.pyi:11:9
+   |
+ 9 | class Child(Parent):
+10 |     # compatible with the signature of `Parent.method`, but not with `Grandparent.method`:
+11 |     def method(self, x: str) -> None: ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Grandparent.method`
+12 |
+13 | class OtherChild(Parent):
+   |
+  ::: src/stub.pyi:4:9
+   |
+ 3 | class Grandparent:
+ 4 |     def method(self, x: int) -> None: ...
+   |         ---------------------------- `Grandparent.method` defined here
+ 5 |
+ 6 | class Parent(Grandparent):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+  --> src/stub.pyi:15:9
+   |
+13 | class OtherChild(Parent):
+14 |     # compatible with the signature of `Grandparent.method`, but not with `Parent.method`:
+15 |     def method(self, x: int) -> None: ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Parent.method`
+16 |
+17 | class GradualParent(Grandparent):
+   |
+  ::: src/stub.pyi:7:9
+   |
+ 6 | class Parent(Grandparent):
+ 7 |     def method(self, x: str) -> None: ...  # error: [invalid-method-override]
+   |         ---------------------------- `Parent.method` defined here
+ 8 |
+ 9 | class Child(Parent):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `method`
+  --> src/stub.pyi:24:9
+   |
+22 |     # and `ThirdChild.method` is compatible with the signature of `GradualParent.method`,
+23 |     # but `ThirdChild.method` is not compatible with the signature of `Grandparent.method`
+24 |     def method(self, x: str) -> None: ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Grandparent.method`
+   |
+  ::: src/stub.pyi:4:9
+   |
+ 3 | class Grandparent:
+ 4 |     def method(self, x: int) -> None: ...
+   |         ---------------------------- `Grandparent.method` defined here
+ 5 |
+ 6 | class Parent(Grandparent):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `get`
+ --> src/other_stub.pyi:2:9
+  |
+1 | class A:
+2 |     def get(self, default): ...
+  |         ------------------ `A.get` defined here
+3 |
+4 | class B(A):
+5 |     def get(self, default, /): ...  # error: [invalid-method-override]
+  |         ^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `A.get`
+6 |
+7 | get = 56
+  |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```
+
+```
+error[invalid-method-override]: Invalid override of method `get`
+  --> src/other_stub.pyi:16:9
+   |
+14 | class D(C):
+15 |     # compatible with `C.get` and `B.get`, but not with `A.get`
+16 |     def get(self, my_default): ...  # error: [invalid-method-override]
+   |         ^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `A.get`
+   |
+  ::: src/other_stub.pyi:2:9
+   |
+ 1 | class A:
+ 2 |     def get(self, default): ...
+   |         ------------------ `A.get` defined here
+ 3 |
+ 4 | class B(A):
+   |
+info: This violates the Liskov Substitution Principle
+info: rule `invalid-method-override` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/mro.md_-_Method_Resolution_Or…_-_`__bases__`_lists_wi…_(ea7ebc83ec359b54).snap

@@ -303,13 +303,13 @@ info: rule `duplicate-base` is enabled by default
 ```
 
 ```
-info[unused-ignore-comment]
+info[unused-ignore-comment]: Unused blanket `type: ignore` directive
   --> src/mdtest_snippet.py:72:9
    |
 70 |     A,
 71 |     # error: [unused-ignore-comment]
 72 |     A,  # type: ignore[duplicate-base]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Unused blanket `type: ignore` directive
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 73 | ): ...
    |
 
@@ -346,13 +346,13 @@ info: rule `duplicate-base` is enabled by default
 ```
 
 ```
-info[unused-ignore-comment]
+info[unused-ignore-comment]: Unused blanket `type: ignore` directive
   --> src/mdtest_snippet.py:81:13
    |
 79 | ):
 80 |     # error: [unused-ignore-comment]
 81 |     x: int  # type: ignore[duplicate-base]
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Unused blanket `type: ignore` directive
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 82 |
 83 | # fmt: on
    |

crates/ty_python_semantic/resources/mdtest/snapshots/tuples.md_-_Comparison___Tuples_-_Equality_with_elemen…_(39b614d4707c0661).snap

@@ -12,27 +12,59 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/comparison/tuples.md
 ## mdtest_snippet.py
 
 ```
-1 | class NotBoolable:
-2 |     __bool__: None = None
-3 | 
-4 | class A:
-5 |     def __eq__(self, other) -> NotBoolable:
-6 |         return NotBoolable()
-7 | 
-8 | # error: [unsupported-bool-conversion]
-9 | (A(),) == (A(),)
+ 1 | class NotBoolable:
+ 2 |     __bool__: None = None
+ 3 | 
+ 4 | class A:
+ 5 |     # error: [invalid-method-override]
+ 6 |     def __eq__(self, other) -> NotBoolable:
+ 7 |         return NotBoolable()
+ 8 | 
+ 9 | # error: [unsupported-bool-conversion]
+10 | (A(),) == (A(),)
 ```
 
 # Diagnostics
 
+```
+error[invalid-method-override]: Invalid override of method `__eq__`
+   --> src/mdtest_snippet.py:6:9
+    |
+  4 | class A:
+  5 |     # error: [invalid-method-override]
+  6 |     def __eq__(self, other) -> NotBoolable:
+    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `object.__eq__`
+  7 |         return NotBoolable()
+    |
+   ::: stdlib/builtins.pyi:142:9
+    |
+140 |     def __setattr__(self, name: str, value: Any, /) -> None: ...
+141 |     def __delattr__(self, name: str, /) -> None: ...
+142 |     def __eq__(self, value: object, /) -> bool: ...
+    |         -------------------------------------- `object.__eq__` defined here
+143 |     def __ne__(self, value: object, /) -> bool: ...
+144 |     def __str__(self) -> str: ...  # noqa: Y029
+    |
+info: This violates the Liskov Substitution Principle
+help: It is recommended for `__eq__` to work with arbitrary objects, for example:
+help
+help:     def __eq__(self, other: object) -> bool:
+help:         if not isinstance(other, A):
+help:             return False
+help:         return <logic to compare two `A` instances>
+help
+info: rule `invalid-method-override` is enabled by default
+
+```
+
 ```
 error[unsupported-bool-conversion]: Boolean conversion is unsupported for type `NotBoolable`
- --> src/mdtest_snippet.py:9:1
-  |
-8 | # error: [unsupported-bool-conversion]
-9 | (A(),) == (A(),)
-  | ^^^^^^^^^^^^^^^^
-  |
+  --> src/mdtest_snippet.py:10:1
+   |
+ 9 | # error: [unsupported-bool-conversion]
+10 | (A(),) == (A(),)
+   | ^^^^^^^^^^^^^^^^
+   |
 info: `__bool__` on `NotBoolable` must be callable
 info: rule `unsupported-bool-conversion` is enabled by default
 

crates/ty_python_semantic/resources/mdtest/snapshots/unresolved_import.md_-_Unresolved_import_di…_-_Using_`from`_with_an…_(6cff507dc64a1bff).snap

@@ -28,6 +28,10 @@ error[unresolved-import]: Cannot resolve imported module `.does_not_exist.foo.ba
 2 |
 3 | stat = add(10, 15)
   |
+info: Searched in the following paths during module resolution:
+info:   1. /src (first-party code)
+info:   2. vendored://stdlib (stdlib typeshed stubs vendored by ty)
+info: make sure your Python environment is properly configured: https://docs.astral.sh/ty/modules/#python-environment
 info: rule `unresolved-import` is enabled by default
 
 ```

crates/ty_python_semantic/resources/mdtest/snapshots/unresolved_import.md_-_Unresolved_import_di…_-_Using_`from`_with_an…_(9da56616d6332a83).snap

@@ -28,6 +28,10 @@ error[unresolved-import]: Cannot resolve imported module `.does_not_exist`
 2 |
 3 | stat = add(10, 15)
   |
+info: Searched in the following paths during module resolution:
+info:   1. /src (first-party code)
+info:   2. vendored://stdlib (stdlib typeshed stubs vendored by ty)
+info: make sure your Python environment is properly configured: https://docs.astral.sh/ty/modules/#python-environment
 info: rule `unresolved-import` is enabled by default
 
 ```