Prefer breaking return-type over parameters

.editorconfig

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

.github/workflows/ci.yaml

@@ -16,7 +16,7 @@ env:
   CARGO_TERM_COLOR: always
   RUSTUP_MAX_RETRIES: 10
   PACKAGE_NAME: ruff
-  PYTHON_VERSION: "3.12"
+  PYTHON_VERSION: "3.11"
 
 jobs:
   determine_changes:
@@ -268,7 +268,6 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           workspaces: "fuzz -> target"
-          cache-all-crates: "true"
       - name: "Install cargo-binstall"
         uses: cargo-bins/cargo-binstall@main
         with:

.github/workflows/publish-playground.yml

@@ -47,7 +47,7 @@ jobs:
         working-directory: playground
       - name: "Deploy to Cloudflare Pages"
         if: ${{ env.CF_API_TOKEN_EXISTS == 'true' }}
-        uses: cloudflare/wrangler-action@v3.12.1
+        uses: cloudflare/wrangler-action@v3.11.0
         with:
           apiToken: ${{ secrets.CF_API_TOKEN }}
           accountId: ${{ secrets.CF_ACCOUNT_ID }}

.pre-commit-config.yaml

@@ -17,7 +17,7 @@ exclude: |
 
 repos:
   - repo: https://github.com/abravalheri/validate-pyproject
-    rev: v0.23
+    rev: v0.22
     hooks:
       - id: validate-pyproject
 
@@ -53,13 +53,13 @@ repos:
         files: '^crates/.*/resources/mdtest/.*\.md'
         exclude: |
           (?x)^(
-            .*?invalid(_.+)*_syntax\.md
+            .*?invalid(_.+)_syntax.md
           )$
         additional_dependencies:
           - black==24.10.0
 
   - repo: https://github.com/crate-ci/typos
-    rev: v1.27.3
+    rev: v1.27.0
     hooks:
       - id: typos
 
@@ -73,7 +73,7 @@ repos:
         pass_filenames: false # This makes it a lot faster
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.7.4
+    rev: v0.7.2
     hooks:
       - id: ruff-format
       - id: ruff

CHANGELOG.md

@@ -1,91 +1,5 @@
 # Changelog
 
-## 0.7.4
-
-### Preview features
-
-- \[`flake8-datetimez`\] Detect usages of `datetime.max`/`datetime.min` (`DTZ901`) ([#14288](https://github.com/astral-sh/ruff/pull/14288))
-- \[`flake8-logging`\] Implement `root-logger-calls` (`LOG015`) ([#14302](https://github.com/astral-sh/ruff/pull/14302))
-- \[`flake8-no-pep420`\] Detect empty implicit namespace packages (`INP001`) ([#14236](https://github.com/astral-sh/ruff/pull/14236))
-- \[`flake8-pyi`\] Add "replace with `Self`" fix (`PYI019`) ([#14238](https://github.com/astral-sh/ruff/pull/14238))
-- \[`perflint`\] Implement quick-fix for `manual-list-comprehension` (`PERF401`) ([#13919](https://github.com/astral-sh/ruff/pull/13919))
-- \[`pylint`\] Implement `shallow-copy-environ` (`W1507`) ([#14241](https://github.com/astral-sh/ruff/pull/14241))
-- \[`ruff`\] Implement `none-not-at-end-of-union` (`RUF036`) ([#14314](https://github.com/astral-sh/ruff/pull/14314))
-- \[`ruff`\] Implementation `unsafe-markup-call` from `flake8-markupsafe` plugin (`RUF035`) ([#14224](https://github.com/astral-sh/ruff/pull/14224))
-- \[`ruff`\] Report problems for `attrs` dataclasses (`RUF008`, `RUF009`) ([#14327](https://github.com/astral-sh/ruff/pull/14327))
-
-### Rule changes
-
-- \[`flake8-boolean-trap`\] Exclude dunder methods that define operators (`FBT001`) ([#14203](https://github.com/astral-sh/ruff/pull/14203))
-- \[`flake8-pyi`\] Add "replace with `Self`" fix (`PYI034`) ([#14217](https://github.com/astral-sh/ruff/pull/14217))
-- \[`flake8-pyi`\] Always autofix `duplicate-union-members` (`PYI016`) ([#14270](https://github.com/astral-sh/ruff/pull/14270))
-- \[`flake8-pyi`\] Improve autofix for nested and mixed type unions for `unnecessary-type-union` (`PYI055`) ([#14272](https://github.com/astral-sh/ruff/pull/14272))
-- \[`flake8-pyi`\] Mark fix as unsafe when type annotation contains comments for `duplicate-literal-member` (`PYI062`) ([#14268](https://github.com/astral-sh/ruff/pull/14268))
-
-### Server
-
-- Use the current working directory to resolve settings from `ruff.configuration` ([#14352](https://github.com/astral-sh/ruff/pull/14352))
-
-### Bug fixes
-
-- Avoid conflicts between `PLC014` (`useless-import-alias`) and `I002` (`missing-required-import`) by considering `lint.isort.required-imports` for `PLC014` ([#14287](https://github.com/astral-sh/ruff/pull/14287))
-- \[`flake8-type-checking`\] Skip quoting annotation if it becomes invalid syntax (`TCH001`)
-- \[`flake8-pyi`\] Avoid using `typing.Self` in stub files pre-Python 3.11 (`PYI034`) ([#14230](https://github.com/astral-sh/ruff/pull/14230))
-- \[`flake8-pytest-style`\] Flag `pytest.raises` call with keyword argument `expected_exception` (`PT011`) ([#14298](https://github.com/astral-sh/ruff/pull/14298))
-- \[`flake8-simplify`\] Infer "unknown" truthiness for literal iterables whose items are all unpacks (`SIM222`) ([#14263](https://github.com/astral-sh/ruff/pull/14263))
-- \[`flake8-type-checking`\] Fix false positives for `typing.Annotated` (`TCH001`) ([#14311](https://github.com/astral-sh/ruff/pull/14311))
-- \[`pylint`\] Allow `await` at the top-level scope of a notebook (`PLE1142`) ([#14225](https://github.com/astral-sh/ruff/pull/14225))
-- \[`pylint`\] Fix miscellaneous issues in `await-outside-async` detection (`PLE1142`) ([#14218](https://github.com/astral-sh/ruff/pull/14218))
-- \[`pyupgrade`\] Avoid applying PEP 646 rewrites in invalid contexts (`UP044`) ([#14234](https://github.com/astral-sh/ruff/pull/14234))
-- \[`pyupgrade`\] Detect permutations in redundant open modes (`UP015`) ([#14255](https://github.com/astral-sh/ruff/pull/14255))
-- \[`refurb`\] Avoid triggering `hardcoded-string-charset` for reordered sets (`FURB156`) ([#14233](https://github.com/astral-sh/ruff/pull/14233))
-- \[`refurb`\] Further special cases added to `verbose-decimal-constructor` (`FURB157`) ([#14216](https://github.com/astral-sh/ruff/pull/14216))
-- \[`refurb`\] Use `UserString` instead of non-existent `UserStr` (`FURB189`) ([#14209](https://github.com/astral-sh/ruff/pull/14209))
-- \[`ruff`\] Avoid treating lowercase letters as `# noqa` codes (`RUF100`) ([#14229](https://github.com/astral-sh/ruff/pull/14229))
-- \[`ruff`\] Do not report when `Optional` has no type arguments (`RUF013`) ([#14181](https://github.com/astral-sh/ruff/pull/14181))
-
-### Documentation
-
-- Add "Notebook behavior" section for `F704`, `PLE1142` ([#14266](https://github.com/astral-sh/ruff/pull/14266))
-- Document comment policy around fix safety ([#14300](https://github.com/astral-sh/ruff/pull/14300))
-
-## 0.7.3
-
-### Preview features
-
-- Formatter: Disallow single-line implicit concatenated strings ([#13928](https://github.com/astral-sh/ruff/pull/13928))
-- \[`flake8-pyi`\] Include all Python file types for `PYI006` and `PYI066` ([#14059](https://github.com/astral-sh/ruff/pull/14059))
-- \[`flake8-simplify`\] Implement `split-of-static-string` (`SIM905`) ([#14008](https://github.com/astral-sh/ruff/pull/14008))
-- \[`refurb`\] Implement `subclass-builtin` (`FURB189`) ([#14105](https://github.com/astral-sh/ruff/pull/14105))
-- \[`ruff`\] Improve diagnostic messages and docs (`RUF031`, `RUF032`, `RUF034`) ([#14068](https://github.com/astral-sh/ruff/pull/14068))
-
-### Rule changes
-
-- Detect items that hash to same value in duplicate sets (`B033`, `PLC0208`) ([#14064](https://github.com/astral-sh/ruff/pull/14064))
-- \[`eradicate`\] Better detection of IntelliJ language injection comments (`ERA001`) ([#14094](https://github.com/astral-sh/ruff/pull/14094))
-- \[`flake8-pyi`\] Add autofix for `docstring-in-stub` (`PYI021`) ([#14150](https://github.com/astral-sh/ruff/pull/14150))
-- \[`flake8-pyi`\] Update `duplicate-literal-member` (`PYI062`) to alawys provide an autofix ([#14188](https://github.com/astral-sh/ruff/pull/14188))
-- \[`pyflakes`\] Detect items that hash to same value in duplicate dictionaries (`F601`) ([#14065](https://github.com/astral-sh/ruff/pull/14065))
-- \[`ruff`\] Fix false positive for decorators (`RUF028`) ([#14061](https://github.com/astral-sh/ruff/pull/14061))
-
-### Bug fixes
-
-- Avoid parsing joint rule codes as distinct codes in `# noqa` ([#12809](https://github.com/astral-sh/ruff/pull/12809))
-- \[`eradicate`\] ignore `# language=` in commented-out-code rule (ERA001) ([#14069](https://github.com/astral-sh/ruff/pull/14069))
-- \[`flake8-bugbear`\] - do not run `mutable-argument-default` on stubs (`B006`) ([#14058](https://github.com/astral-sh/ruff/pull/14058))
-- \[`flake8-builtins`\] Skip lambda expressions in `builtin-argument-shadowing (A002)` ([#14144](https://github.com/astral-sh/ruff/pull/14144))
-- \[`flake8-comprehension`\] Also remove trailing comma while fixing `C409` and `C419` ([#14097](https://github.com/astral-sh/ruff/pull/14097))
-- \[`flake8-simplify`\] Allow `open` without context manager in `return` statement (`SIM115`) ([#14066](https://github.com/astral-sh/ruff/pull/14066))
-- \[`pylint`\] Respect hash-equivalent literals in `iteration-over-set` (`PLC0208`) ([#14063](https://github.com/astral-sh/ruff/pull/14063))
-- \[`pylint`\] Update known dunder methods for Python 3.13 (`PLW3201`) ([#14146](https://github.com/astral-sh/ruff/pull/14146))
-- \[`pyupgrade`\] - ignore kwarg unpacking for `UP044` ([#14053](https://github.com/astral-sh/ruff/pull/14053))
-- \[`refurb`\] Parse more exotic decimal strings in `verbose-decimal-constructor` (`FURB157`) ([#14098](https://github.com/astral-sh/ruff/pull/14098))
-
-### Documentation
-
-- Add links to missing related options within rule documentations ([#13971](https://github.com/astral-sh/ruff/pull/13971))
-- Add rule short code to mkdocs tags to allow searching via rule codes ([#14040](https://github.com/astral-sh/ruff/pull/14040))
-
 ## 0.7.2
 
 ### Preview features

Cargo.lock

@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "Inflector"
+version = "0.11.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fe438c63458706e03479442743baae6c88256498e6431708f6dfc520a26515d3"
+
 [[package]]
 name = "adler"
 version = "1.0.2"
@@ -117,9 +123,9 @@ dependencies = [
 
 [[package]]
 name = "anyhow"
-version = "1.0.93"
+version = "1.0.92"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4c95c10ba0b00a02636238b814946408b1322d5ac4760326e6fb8ec956d85775"
+checksum = "74f37166d7d48a0284b99dd824694c26119c700b53bf0d1540cdb147dbdaaf13"
 
 [[package]]
 name = "append-only-vec"
@@ -170,12 +176,6 @@ version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f1fdabc7756949593fe60f30ec81974b613357de856987752631dea1e3394c80"
 
-[[package]]
-name = "base64"
-version = "0.13.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e1b586273c5702936fe7b7d6896644d8be71e6314cfe09d3167c95f712589e8"
-
 [[package]]
 name = "base64"
 version = "0.22.0"
@@ -214,9 +214,9 @@ dependencies = [
 
 [[package]]
 name = "bstr"
-version = "1.11.0"
+version = "1.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1a68f1f47cdf0ec8ee4b941b2eee2a80cb796db73118c0dd09ac63fbe405be22"
+checksum = "40723b8fb387abc38f4f4a37c09073622e41dd12327033091ef8950659e6dc0c"
 dependencies = [
  "memchr",
  "regex-automata 0.4.8",
@@ -347,9 +347,9 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.5.21"
+version = "4.5.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fb3b4b9e5a7c7514dfa52869339ee98b3156b0bfb4e8a77c4ff4babb64b1604f"
+checksum = "b97f376d85a664d5837dbae44bf546e6477a679ff6610010f17276f686d867e8"
 dependencies = [
  "clap_builder",
  "clap_derive",
@@ -357,9 +357,9 @@ dependencies = [
 
 [[package]]
 name = "clap_builder"
-version = "4.5.21"
+version = "4.5.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b17a95aa67cc7b5ebd32aa5370189aa0d79069ef1c64ce893bd30fb24bff20ec"
+checksum = "19bc80abd44e4bed93ca373a0704ccbd1b710dc5749406201bb018272808dc54"
 dependencies = [
  "anstream",
  "anstyle",
@@ -424,7 +424,7 @@ checksum = "2f8c93eb5f77c9050c7750e14f13ef1033a40a0aac70c6371535b6763a01438c"
 dependencies = [
  "nix 0.28.0",
  "terminfo",
- "thiserror 1.0.67",
+ "thiserror",
  "which",
  "winapi",
 ]
@@ -812,17 +812,6 @@ dependencies = [
  "windows-sys 0.48.0",
 ]
 
-[[package]]
-name = "displaydoc"
-version = "0.2.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "97369cbbc041bc366949bc74d34658d6cda5621039731c6310521892a3a20ae0"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.87",
-]
-
 [[package]]
 name = "doc-comment"
 version = "0.3.3"
@@ -835,12 +824,6 @@ version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9bda8e21c04aca2ae33ffc2fd8c23134f3cac46db123ba97bd9d3f3b8a4a85e1"
 
-[[package]]
-name = "dunce"
-version = "1.0.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "92773504d58c093f6de2459af4af33faa518c13451eb8f2b5698ed3d36e7c813"
-
 [[package]]
 name = "dyn-clone"
 version = "1.0.17"
@@ -1062,9 +1045,9 @@ dependencies = [
 
 [[package]]
 name = "hashbrown"
-version = "0.15.1"
+version = "0.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3a9bfc1af68b1726ea47d3d5109de126281def866b33970e10fbab11b5dafab3"
+checksum = "1e087f84d4f86bf4b218b927129862374b72199ae7d8657835f1e89000eea4fb"
 
 [[package]]
 name = "hashlink"
@@ -1125,124 +1108,6 @@ dependencies = [
  "cc",
 ]
 
-[[package]]
-name = "icu_collections"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "db2fa452206ebee18c4b5c2274dbf1de17008e874b4dc4f0aea9d01ca79e4526"
-dependencies = [
- "displaydoc",
- "yoke",
- "zerofrom",
- "zerovec",
-]
-
-[[package]]
-name = "icu_locid"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "13acbb8371917fc971be86fc8057c41a64b521c184808a698c02acc242dbf637"
-dependencies = [
- "displaydoc",
- "litemap",
- "tinystr",
- "writeable",
- "zerovec",
-]
-
-[[package]]
-name = "icu_locid_transform"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "01d11ac35de8e40fdeda00d9e1e9d92525f3f9d887cdd7aa81d727596788b54e"
-dependencies = [
- "displaydoc",
- "icu_locid",
- "icu_locid_transform_data",
- "icu_provider",
- "tinystr",
- "zerovec",
-]
-
-[[package]]
-name = "icu_locid_transform_data"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fdc8ff3388f852bede6b579ad4e978ab004f139284d7b28715f773507b946f6e"
-
-[[package]]
-name = "icu_normalizer"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "19ce3e0da2ec68599d193c93d088142efd7f9c5d6fc9b803774855747dc6a84f"
-dependencies = [
- "displaydoc",
- "icu_collections",
- "icu_normalizer_data",
- "icu_properties",
- "icu_provider",
- "smallvec",
- "utf16_iter",
- "utf8_iter",
- "write16",
- "zerovec",
-]
-
-[[package]]
-name = "icu_normalizer_data"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f8cafbf7aa791e9b22bec55a167906f9e1215fd475cd22adfcf660e03e989516"
-
-[[package]]
-name = "icu_properties"
-version = "1.5.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "93d6020766cfc6302c15dbbc9c8778c37e62c14427cb7f6e601d849e092aeef5"
-dependencies = [
- "displaydoc",
- "icu_collections",
- "icu_locid_transform",
- "icu_properties_data",
- "icu_provider",
- "tinystr",
- "zerovec",
-]
-
-[[package]]
-name = "icu_properties_data"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "67a8effbc3dd3e4ba1afa8ad918d5684b8868b3b26500753effea8d2eed19569"
-
-[[package]]
-name = "icu_provider"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6ed421c8a8ef78d3e2dbc98a973be2f3770cb42b606e3ab18d6237c4dfde68d9"
-dependencies = [
- "displaydoc",
- "icu_locid",
- "icu_provider_macros",
- "stable_deref_trait",
- "tinystr",
- "writeable",
- "yoke",
- "zerofrom",
- "zerovec",
-]
-
-[[package]]
-name = "icu_provider_macros"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ec89e9337638ecdc08744df490b221a7399bf8d164eb52a665454e60e075ad6"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.87",
-]
-
 [[package]]
 name = "ident_case"
 version = "1.0.1"
@@ -1251,23 +1116,12 @@ checksum = "b9e0384b61958566e926dc50660321d12159025e767c18e043daf26b70104c39"
 
 [[package]]
 name = "idna"
-version = "1.0.3"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "686f825264d630750a544639377bae737628043f20d38bbc029e8f29ea968a7e"
+checksum = "634d9b1461af396cad843f47fdba5597a4f9e6ddd4bfb6ff5d85028c25cb12f6"
 dependencies = [
- "idna_adapter",
- "smallvec",
- "utf8_iter",
-]
-
-[[package]]
-name = "idna_adapter"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "daca1df1c957320b2cf139ac61e7bd64fed304c5040df000a745aa1de3b4ef71"
-dependencies = [
- "icu_normalizer",
- "icu_properties",
+ "unicode-bidi",
+ "unicode-normalization",
 ]
 
 [[package]]
@@ -1313,22 +1167,22 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "707907fe3c25f5424cce2cb7e1cbcafee6bdbe735ca90ef77c29e84591e5b9da"
 dependencies = [
  "equivalent",
- "hashbrown 0.15.1",
+ "hashbrown 0.15.0",
  "serde",
 ]
 
 [[package]]
 name = "indicatif"
-version = "0.17.9"
+version = "0.17.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cbf675b85ed934d3c67b5c5469701eec7db22689d0a2139d856e0925fa28b281"
+checksum = "763a5a8f45087d6bcea4222e7b72c291a054edf80e4ef6efd2a4979878c7bea3"
 dependencies = [
  "console",
+ "instant",
  "number_prefix",
  "portable-atomic",
- "unicode-width 0.2.0",
+ "unicode-width 0.1.13",
  "vt100",
- "web-time",
 ]
 
 [[package]]
@@ -1370,7 +1224,6 @@ dependencies = [
  "pest",
  "pest_derive",
  "regex",
- "ron",
  "serde",
  "similar",
  "walkdir",
@@ -1407,11 +1260,11 @@ dependencies = [
 
 [[package]]
 name = "is-macro"
-version = "0.3.7"
+version = "0.3.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1d57a3e447e24c22647738e4607f1df1e0ec6f72e16182c4cd199f647cdfb0e4"
+checksum = "2069faacbe981460232f880d26bf3c7634e322d49053aa48c27e3ae642f728f1"
 dependencies = [
- "heck",
+ "Inflector",
  "proc-macro2",
  "quote",
  "syn 2.0.87",
@@ -1514,9 +1367,9 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
 [[package]]
 name = "libc"
-version = "0.2.164"
+version = "0.2.161"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "433bfe06b8c75da9b2e3fbea6e5329ff87748f0b144ef75306e674c3f6f7c13f"
+checksum = "8e9489c2807c139ffd9c1794f4af0ebe86a828db53ecdc7fea2111d0fed085d1"
 
 [[package]]
 name = "libcst"
@@ -1530,7 +1383,7 @@ dependencies = [
  "paste",
  "peg",
  "regex",
- "thiserror 1.0.67",
+ "thiserror",
 ]
 
 [[package]]
@@ -1576,12 +1429,6 @@ version = "0.4.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "78b3ae25bc7c8c38cec158d1f2757ee79e9b3740fbc7ccf0e59e4b08d793fa89"
 
-[[package]]
-name = "litemap"
-version = "0.7.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "643cb0b8d4fcc284004d5fd0d67ccf61dfffadb7f75e1e71bc420f4688a3a704"
-
 [[package]]
 name = "lock_api"
 version = "0.4.11"
@@ -1639,9 +1486,9 @@ checksum = "2532096657941c2fea9c289d370a250971c689d4f143798ff67113ec042024a5"
 
 [[package]]
 name = "matchit"
-version = "0.8.5"
+version = "0.8.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bd0aa4b8ca861b08d68afc8702af3250776898c1508b278e1da9d01e01d4b45c"
+checksum = "47e1ffaa40ddd1f3ed91f717a33c8c0ee23fff369e3aa8772b9605cc1d22f4c3"
 
 [[package]]
 name = "memchr"
@@ -1968,7 +1815,7 @@ dependencies = [
  "pep440_rs 0.4.0",
  "regex",
  "serde",
- "thiserror 1.0.67",
+ "thiserror",
  "tracing",
  "unicode-width 0.1.13",
  "url",
@@ -1987,7 +1834,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cd53dff83f26735fdc1ca837098ccf133605d794cdae66acfc2bfac3ec809d95"
 dependencies = [
  "memchr",
- "thiserror 1.0.67",
+ "thiserror",
  "ucd-trie",
 ]
 
@@ -2157,7 +2004,7 @@ dependencies = [
  "newtype-uuid",
  "quick-xml",
  "strip-ansi-escapes",
- "thiserror 1.0.67",
+ "thiserror",
  "uuid",
 ]
 
@@ -2264,7 +2111,7 @@ dependencies = [
  "compact_str",
  "countme",
  "dir-test",
- "hashbrown 0.15.1",
+ "hashbrown 0.15.0",
  "indexmap",
  "insta",
  "itertools 0.13.0",
@@ -2282,12 +2129,11 @@ dependencies = [
  "ruff_text_size",
  "rustc-hash 2.0.0",
  "salsa",
- "serde",
  "smallvec",
  "static_assertions",
  "tempfile",
  "test-case",
- "thiserror 2.0.3",
+ "thiserror",
  "tracing",
 ]
 
@@ -2327,6 +2173,7 @@ dependencies = [
  "regex",
  "ruff_db",
  "ruff_index",
+ "ruff_python_parser",
  "ruff_python_trivia",
  "ruff_source_file",
  "ruff_text_size",
@@ -2367,10 +2214,7 @@ version = "0.0.0"
 dependencies = [
  "anyhow",
  "crossbeam",
- "glob",
- "insta",
  "notify",
- "pep440_rs 0.7.2",
  "rayon",
  "red_knot_python_semantic",
  "red_knot_vendored",
@@ -2380,9 +2224,7 @@ dependencies = [
  "ruff_text_size",
  "rustc-hash 2.0.0",
  "salsa",
- "serde",
- "thiserror 2.0.3",
- "toml",
+ "tempfile",
  "tracing",
 ]
 
@@ -2412,7 +2254,7 @@ checksum = "bd283d9651eeda4b2a83a43c1c91b266c40fd76ecd39a50a8c630ae69dc72891"
 dependencies = [
  "getrandom",
  "libredox",
- "thiserror 1.0.67",
+ "thiserror",
 ]
 
 [[package]]
@@ -2474,20 +2316,9 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
-[[package]]
-name = "ron"
-version = "0.7.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "88073939a61e5b7680558e6be56b419e208420c2adb92be54921fa6b72283f1a"
-dependencies = [
- "base64 0.13.1",
- "bitflags 1.3.2",
- "serde",
-]
-
 [[package]]
 name = "ruff"
-version = "0.7.4"
+version = "0.7.2"
 dependencies = [
  "anyhow",
  "argfile",
@@ -2534,7 +2365,7 @@ dependencies = [
  "strum",
  "tempfile",
  "test-case",
- "thiserror 2.0.3",
+ "thiserror",
  "tikv-jemallocator",
  "toml",
  "tracing",
@@ -2586,9 +2417,7 @@ dependencies = [
  "camino",
  "countme",
  "dashmap 6.1.0",
- "dunce",
  "filetime",
- "glob",
  "ignore",
  "insta",
  "matchit",
@@ -2604,7 +2433,7 @@ dependencies = [
  "salsa",
  "serde",
  "tempfile",
- "thiserror 2.0.3",
+ "thiserror",
  "tracing",
  "tracing-subscriber",
  "tracing-tree",
@@ -2706,7 +2535,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_linter"
-version = "0.7.4"
+version = "0.7.2"
 dependencies = [
  "aho-corasick",
  "annotate-snippets 0.9.2",
@@ -2756,7 +2585,7 @@ dependencies = [
  "strum",
  "strum_macros",
  "test-case",
- "thiserror 2.0.3",
+ "thiserror",
  "toml",
  "typed-arena",
  "unicode-normalization",
@@ -2790,7 +2619,7 @@ dependencies = [
  "serde_json",
  "serde_with",
  "test-case",
- "thiserror 2.0.3",
+ "thiserror",
  "uuid",
 ]
 
@@ -2810,6 +2639,7 @@ dependencies = [
  "ruff_source_file",
  "ruff_text_size",
  "rustc-hash 2.0.0",
+ "salsa",
  "schemars",
  "serde",
 ]
@@ -2862,7 +2692,7 @@ dependencies = [
  "similar",
  "smallvec",
  "static_assertions",
- "thiserror 2.0.3",
+ "thiserror",
  "tracing",
 ]
 
@@ -2942,7 +2772,6 @@ dependencies = [
 name = "ruff_python_stdlib"
 version = "0.0.0"
 dependencies = [
- "bitflags 2.6.0",
  "unicode-ident",
 ]
 
@@ -2995,7 +2824,7 @@ dependencies = [
  "serde",
  "serde_json",
  "shellexpand",
- "thiserror 2.0.3",
+ "thiserror",
  "tracing",
  "tracing-subscriber",
 ]
@@ -3021,7 +2850,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_wasm"
-version = "0.7.4"
+version = "0.7.2"
 dependencies = [
  "console_error_panic_hook",
  "console_log",
@@ -3104,9 +2933,9 @@ checksum = "583034fd73374156e66797ed8e5b0d5690409c9226b22d87cb7f19821c05d152"
 
 [[package]]
 name = "rustix"
-version = "0.38.40"
+version = "0.38.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "99e4ea3e1cdc4b559b8e5650f9c8e5998e3e5c1343b4eaf034565f32318d63c0"
+checksum = "8acb788b847c24f28525660c4d7758620a7210875711f79e7f663cc152726811"
 dependencies = [
  "bitflags 2.6.0",
  "errno",
@@ -3249,9 +3078,9 @@ checksum = "1c107b6f4780854c8b126e228ea8869f4d7b71260f962fefb57b996b8959ba6b"
 
 [[package]]
 name = "serde"
-version = "1.0.215"
+version = "1.0.214"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6513c1ad0b11a9376da888e3e0baa0077f1aed55c17f50e7b2397136129fb88f"
+checksum = "f55c3193aca71c12ad7890f1785d2b73e1b9f63a0bbc353c08ef26fe03fc56b5"
 dependencies = [
  "serde_derive",
 ]
@@ -3269,9 +3098,9 @@ dependencies = [
 
 [[package]]
 name = "serde_derive"
-version = "1.0.215"
+version = "1.0.214"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ad1e866f866923f252f05c889987993144fb74e722403468a4ebd70c3cd756c0"
+checksum = "de523f781f095e28fa605cdce0f8307e451cc0fd14e2eb4cd2e98a355b147766"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -3291,9 +3120,9 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.133"
+version = "1.0.132"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c7fceb2473b9166b2294ef05efcb65a3db80803f0b03ef86a5fc88a2b85ee377"
+checksum = "d726bfaff4b320266d395898905d0eba0345aae23b54aee3a737e260fd46db03"
 dependencies = [
  "itoa",
  "memchr",
@@ -3406,12 +3235,6 @@ version = "0.9.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
 
-[[package]]
-name = "stable_deref_trait"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a8f112729512f8e442d81f95a8a7ddf2b7c6b8a1a6f509a95864142b30cab2d3"
-
 [[package]]
 name = "static_assertions"
 version = "1.1.0"
@@ -3502,9 +3325,9 @@ dependencies = [
 
 [[package]]
 name = "tempfile"
-version = "3.14.0"
+version = "3.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "28cce251fcbc87fac86a866eeb0d6c2d536fc16d06f184bb61aeae11aa4cee0c"
+checksum = "f0f2c9fc62d0beef6951ccffd757e241266a2c833136efbe35af6cd2567dca5b"
 dependencies = [
  "cfg-if",
  "fastrand",
@@ -3581,16 +3404,7 @@ version = "1.0.67"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3b3c6efbfc763e64eb85c11c25320f0737cb7364c4b6336db90aa9ebe27a0bbd"
 dependencies = [
- "thiserror-impl 1.0.67",
-]
-
-[[package]]
-name = "thiserror"
-version = "2.0.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c006c85c7651b3cf2ada4584faa36773bd07bac24acfb39f3c431b36d7e667aa"
-dependencies = [
- "thiserror-impl 2.0.3",
+ "thiserror-impl",
 ]
 
 [[package]]
@@ -3604,17 +3418,6 @@ dependencies = [
  "syn 2.0.87",
 ]
 
-[[package]]
-name = "thiserror-impl"
-version = "2.0.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f077553d607adc1caf65430528a576c757a71ed73944b66ebb58ef2bbd243568"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.87",
-]
-
 [[package]]
 name = "thread_local"
 version = "1.1.8"
@@ -3645,16 +3448,6 @@ dependencies = [
  "tikv-jemalloc-sys",
 ]
 
-[[package]]
-name = "tinystr"
-version = "0.7.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9117f5d4db391c1cf6927e7bea3db74b9a1c1add8f7eda9ffd5364f40f57b82f"
-dependencies = [
- "displaydoc",
- "zerovec",
-]
-
 [[package]]
 name = "tinytemplate"
 version = "1.2.1"
@@ -3871,6 +3664,12 @@ dependencies = [
  "unic-common",
 ]
 
+[[package]]
+name = "unicode-bidi"
+version = "0.3.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "08f95100a766bf4f8f28f90d77e0a5461bbdb219042e7679bebe79004fed8d75"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.13"
@@ -3938,7 +3737,7 @@ version = "2.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b74fc6b57825be3373f7054754755f03ac3a8f5d70015ccad699ba2029956f4a"
 dependencies = [
- "base64 0.22.0",
+ "base64",
  "flate2",
  "log",
  "once_cell",
@@ -3950,9 +3749,9 @@ dependencies = [
 
 [[package]]
 name = "url"
-version = "2.5.3"
+version = "2.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8d157f1b96d14500ffdc1f10ba712e780825526c03d9a49b4d0324b0d9113ada"
+checksum = "22784dbdf76fdde8af1aeda5622b546b422b6fc585325248a2bf9f5e41e94d6c"
 dependencies = [
  "form_urlencoded",
  "idna",
@@ -3960,18 +3759,6 @@ dependencies = [
  "serde",
 ]
 
-[[package]]
-name = "utf16_iter"
-version = "1.0.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c8232dd3cdaed5356e0f716d285e4b40b932ac434100fe9b7e0e8e935b9e6246"
-
-[[package]]
-name = "utf8_iter"
-version = "1.0.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b6c140620e7ffbb22c2dee59cafe6084a59b5ffc27a8859a5f0d494b5d52b6be"
-
 [[package]]
 name = "utf8parse"
 version = "0.2.1"
@@ -4408,18 +4195,6 @@ version = "0.0.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d135d17ab770252ad95e9a872d365cf3090e3be864a34ab46f48555993efc904"
 
-[[package]]
-name = "write16"
-version = "1.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d1890f4022759daae28ed4fe62859b1236caebfc61ede2f63ed4e695f3f6d936"
-
-[[package]]
-name = "writeable"
-version = "0.5.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e9df38ee2d2c3c5948ea468a8406ff0db0b29ae1ffde1bcf20ef305bcc95c51"
-
 [[package]]
 name = "yansi"
 version = "1.0.1"
@@ -4435,30 +4210,6 @@ dependencies = [
  "winapi",
 ]
 
-[[package]]
-name = "yoke"
-version = "0.7.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6c5b1314b079b0930c31e3af543d8ee1757b1951ae1e1565ec704403a7240ca5"
-dependencies = [
- "serde",
- "stable_deref_trait",
- "yoke-derive",
- "zerofrom",
-]
-
-[[package]]
-name = "yoke-derive"
-version = "0.7.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "28cc31741b18cb6f1d5ff12f5b7523e3d6eb0852bbbad19d73905511d9849b95"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.87",
- "synstructure",
-]
-
 [[package]]
 name = "zerocopy"
 version = "0.7.32"
@@ -4479,55 +4230,12 @@ dependencies = [
  "syn 2.0.87",
 ]
 
-[[package]]
-name = "zerofrom"
-version = "0.1.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "91ec111ce797d0e0784a1116d0ddcdbea84322cd79e5d5ad173daeba4f93ab55"
-dependencies = [
- "zerofrom-derive",
-]
-
-[[package]]
-name = "zerofrom-derive"
-version = "0.1.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0ea7b4a3637ea8669cedf0f1fd5c286a17f3de97b8dd5a70a6c167a1730e63a5"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.87",
- "synstructure",
-]
-
 [[package]]
 name = "zeroize"
 version = "1.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "525b4ec142c6b68a2d10f01f7bbf6755599ca3f81ea53b8431b7dd348f5fdb2d"
 
-[[package]]
-name = "zerovec"
-version = "0.10.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "aa2b893d79df23bfb12d5461018d408ea19dfafe76c2c7ef6d4eba614f8ff079"
-dependencies = [
- "yoke",
- "zerofrom",
- "zerovec-derive",
-]
-
-[[package]]
-name = "zerovec-derive"
-version = "0.10.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6eafa6dfb17584ea3e2bd6e76e0cc15ad7af12b09abdd1ca55961bed9b1063c6"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.87",
-]
-
 [[package]]
 name = "zip"
 version = "0.6.6"

Cargo.toml

@@ -66,7 +66,6 @@ criterion = { version = "0.5.1", default-features = false }
 crossbeam = { version = "0.8.4" }
 dashmap = { version = "6.0.1" }
 dir-test = { version = "0.3.0" }
-dunce = { version = "1.0.5" }
 drop_bomb = { version = "0.1.5" }
 env_logger = { version = "0.11.0" }
 etcetera = { version = "0.8.0" }
@@ -82,7 +81,7 @@ hashbrown = { version = "0.15.0", default-features = false, features = [
 ignore = { version = "0.4.22" }
 imara-diff = { version = "0.1.5" }
 imperative = { version = "1.0.4" }
-indexmap = { version = "2.6.0" }
+indexmap = {version = "2.6.0" }
 indicatif = { version = "0.17.8" }
 indoc = { version = "2.0.4" }
 insta = { version = "1.35.1" }
@@ -137,7 +136,7 @@ strum_macros = { version = "0.26.0" }
 syn = { version = "2.0.55" }
 tempfile = { version = "3.9.0" }
 test-case = { version = "3.3.1" }
-thiserror = { version = "2.0.0" }
+thiserror = { version = "1.0.58" }
 tikv-jemallocator = { version = "0.6.0" }
 toml = { version = "0.8.11" }
 tracing = { version = "0.1.40" }

README.md

@@ -136,8 +136,8 @@ curl -LsSf https://astral.sh/ruff/install.sh | sh
 powershell -c "irm https://astral.sh/ruff/install.ps1 | iex"
 
 # For a specific version.
-curl -LsSf https://astral.sh/ruff/0.7.4/install.sh | sh
-powershell -c "irm https://astral.sh/ruff/0.7.4/install.ps1 | iex"
+curl -LsSf https://astral.sh/ruff/0.7.2/install.sh | sh
+powershell -c "irm https://astral.sh/ruff/0.7.2/install.ps1 | iex"
 ```
 
 You can also install Ruff via [Homebrew](https://formulae.brew.sh/formula/ruff), [Conda](https://anaconda.org/conda-forge/ruff),
@@ -170,7 +170,7 @@ Ruff can also be used as a [pre-commit](https://pre-commit.com/) hook via [`ruff
 ```yaml
 - repo: https://github.com/astral-sh/ruff-pre-commit
   # Ruff version.
-  rev: v0.7.4
+  rev: v0.7.2
   hooks:
     # Run the linter.
     - id: ruff

_typos.toml

@@ -1,11 +1,6 @@
 [files]
 # https://github.com/crate-ci/typos/issues/868
-extend-exclude = [
-  "crates/red_knot_vendored/vendor/**/*",
-  "**/resources/**/*",
-  "**/snapshots/**/*",
-  "crates/red_knot_workspace/src/workspace/pyproject/package_name.rs"
-]
+extend-exclude = ["crates/red_knot_vendored/vendor/**/*", "**/resources/**/*", "**/snapshots/**/*"]
 
 [default.extend-words]
 "arange" = "arange"  # e.g. `numpy.arange`

crates/red_knot/Cargo.toml

@@ -34,7 +34,6 @@ tracing-tree = { workspace = true }
 [dev-dependencies]
 filetime = { workspace = true }
 tempfile = { workspace = true }
-ruff_db = { workspace = true, features = ["testing"] }
 
 [lints]
 workspace = true

crates/red_knot/src/main.rs

@@ -5,6 +5,8 @@ use anyhow::{anyhow, Context};
 use clap::Parser;
 use colored::Colorize;
 use crossbeam::channel as crossbeam_channel;
+use salsa::plumbing::ZalsaDatabase;
+
 use red_knot_python_semantic::SitePackages;
 use red_knot_server::run_server;
 use red_knot_workspace::db::RootDatabase;
@@ -12,9 +14,7 @@ use red_knot_workspace::watch;
 use red_knot_workspace::watch::WorkspaceWatcher;
 use red_knot_workspace::workspace::settings::Configuration;
 use red_knot_workspace::workspace::WorkspaceMetadata;
-use ruff_db::diagnostic::Diagnostic;
 use ruff_db::system::{OsSystem, System, SystemPath, SystemPathBuf};
-use salsa::plumbing::ZalsaDatabase;
 use target_version::TargetVersion;
 
 use crate::logging::{setup_tracing, Verbosity};
@@ -183,10 +183,10 @@ fn run() -> anyhow::Result<ExitStatus> {
 
     let system = OsSystem::new(cwd.clone());
     let cli_configuration = args.to_configuration(&cwd);
-    let workspace_metadata = WorkspaceMetadata::discover(
+    let workspace_metadata = WorkspaceMetadata::from_path(
         system.current_directory(),
         &system,
-        Some(&cli_configuration),
+        Some(cli_configuration.clone()),
     )?;
 
     // TODO: Use the `program_settings` to compute the key for the database's persistent
@@ -318,9 +318,8 @@ impl MainLoop {
                 } => {
                     let has_diagnostics = !result.is_empty();
                     if check_revision == revision {
-                        #[allow(clippy::print_stdout)]
                         for diagnostic in result {
-                            println!("{}", diagnostic.display(db));
+                            tracing::error!("{}", diagnostic);
                         }
                     } else {
                         tracing::debug!(
@@ -379,10 +378,7 @@ impl MainLoopCancellationToken {
 #[derive(Debug)]
 enum MainLoopMessage {
     CheckWorkspace,
-    CheckCompleted {
-        result: Vec<Box<dyn Diagnostic>>,
-        revision: u64,
-    },
+    CheckCompleted { result: Vec<String>, revision: u64 },
     ApplyChanges(Vec<watch::ChangeEvent>),
     Exit,
 }

crates/red_knot/src/target_version.rs

@@ -4,8 +4,8 @@
 #[derive(Copy, Clone, Hash, Debug, PartialEq, Eq, PartialOrd, Ord, Default, clap::ValueEnum)]
 pub enum TargetVersion {
     Py37,
-    Py38,
     #[default]
+    Py38,
     Py39,
     Py310,
     Py311,
@@ -46,17 +46,3 @@ impl From<TargetVersion> for red_knot_python_semantic::PythonVersion {
         }
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use crate::target_version::TargetVersion;
-    use red_knot_python_semantic::PythonVersion;
-
-    #[test]
-    fn same_default_as_python_version() {
-        assert_eq!(
-            PythonVersion::from(TargetVersion::default()),
-            PythonVersion::default()
-        );
-    }
-}

crates/red_knot/tests/file_watching.rs

@@ -6,7 +6,7 @@ use std::time::Duration;
 use anyhow::{anyhow, Context};
 
 use red_knot_python_semantic::{resolve_module, ModuleName, Program, PythonVersion, SitePackages};
-use red_knot_workspace::db::{Db, RootDatabase};
+use red_knot_workspace::db::RootDatabase;
 use red_knot_workspace::watch;
 use red_knot_workspace::watch::{directory_watcher, WorkspaceWatcher};
 use red_knot_workspace::workspace::settings::{Configuration, SearchPathConfiguration};
@@ -14,7 +14,6 @@ use red_knot_workspace::workspace::WorkspaceMetadata;
 use ruff_db::files::{system_path_to_file, File, FileError};
 use ruff_db::source::source_text;
 use ruff_db::system::{OsSystem, SystemPath, SystemPathBuf};
-use ruff_db::testing::setup_logging;
 use ruff_db::Upcast;
 
 struct TestCase {
@@ -70,6 +69,7 @@ impl TestCase {
         Some(all_events)
     }
 
+    #[cfg(unix)]
     fn take_watch_changes(&self) -> Vec<watch::ChangeEvent> {
         self.try_take_watch_changes(Duration::from_secs(10))
             .expect("Expected watch changes but observed none")
@@ -110,8 +110,8 @@ impl TestCase {
     ) -> anyhow::Result<()> {
         let program = Program::get(self.db());
 
-        let new_settings = configuration.to_settings(self.db.workspace().root(&self.db));
-        self.configuration.search_paths = configuration;
+        self.configuration.search_paths = configuration.clone();
+        let new_settings = configuration.into_settings(self.db.workspace().root(&self.db));
 
         program.update_search_paths(&mut self.db, &new_settings)?;
 
@@ -204,9 +204,7 @@ where
             .as_utf8_path()
             .canonicalize_utf8()
             .with_context(|| "Failed to canonicalize root path.")?,
-    )
-    .simplified()
-    .to_path_buf();
+    );
 
     let workspace_path = root_path.join("workspace");
 
@@ -243,7 +241,8 @@ where
         search_paths,
     };
 
-    let workspace = WorkspaceMetadata::discover(&workspace_path, &system, Some(&configuration))?;
+    let workspace =
+        WorkspaceMetadata::from_path(&workspace_path, &system, Some(configuration.clone()))?;
 
     let db = RootDatabase::new(workspace, system)?;
 
@@ -1312,138 +1311,3 @@ mod unix {
         Ok(())
     }
 }
-
-#[test]
-fn nested_packages_delete_root() -> anyhow::Result<()> {
-    let mut case = setup(|root: &SystemPath, workspace_root: &SystemPath| {
-        std::fs::write(
-            workspace_root.join("pyproject.toml").as_std_path(),
-            r#"
-            [project]
-            name = "inner"
-            "#,
-        )?;
-
-        std::fs::write(
-            root.join("pyproject.toml").as_std_path(),
-            r#"
-            [project]
-            name = "outer"
-            "#,
-        )?;
-
-        Ok(())
-    })?;
-
-    assert_eq!(
-        case.db().workspace().root(case.db()),
-        &*case.workspace_path("")
-    );
-
-    std::fs::remove_file(case.workspace_path("pyproject.toml").as_std_path())?;
-
-    let changes = case.stop_watch();
-
-    case.apply_changes(changes);
-
-    // It should now pick up the outer workspace.
-    assert_eq!(case.db().workspace().root(case.db()), case.root_path());
-
-    Ok(())
-}
-
-#[test]
-fn added_package() -> anyhow::Result<()> {
-    let _ = setup_logging();
-    let mut case = setup([
-        (
-            "pyproject.toml",
-            r#"
-            [project]
-            name = "inner"
-
-            [tool.knot.workspace]
-            members = ["packages/*"]
-            "#,
-        ),
-        (
-            "packages/a/pyproject.toml",
-            r#"
-            [project]
-            name = "a"
-            "#,
-        ),
-    ])?;
-
-    assert_eq!(case.db().workspace().packages(case.db()).len(), 2);
-
-    std::fs::create_dir(case.workspace_path("packages/b").as_std_path())
-        .context("failed to create folder for package 'b'")?;
-
-    // It seems that the file watcher won't pick up on file changes shortly after the folder
-    // was created... I suspect this is because most file watchers don't support recursive
-    // file watching. Instead, file-watching libraries manually implement recursive file watching
-    // by setting a watcher for each directory. But doing this obviously "lags" behind.
-    case.take_watch_changes();
-
-    std::fs::write(
-        case.workspace_path("packages/b/pyproject.toml")
-            .as_std_path(),
-        r#"
-            [project]
-            name = "b"
-            "#,
-    )
-    .context("failed to write pyproject.toml for package b")?;
-
-    let changes = case.stop_watch();
-
-    case.apply_changes(changes);
-
-    assert_eq!(case.db().workspace().packages(case.db()).len(), 3);
-
-    Ok(())
-}
-
-#[test]
-fn removed_package() -> anyhow::Result<()> {
-    let mut case = setup([
-        (
-            "pyproject.toml",
-            r#"
-            [project]
-            name = "inner"
-
-            [tool.knot.workspace]
-            members = ["packages/*"]
-            "#,
-        ),
-        (
-            "packages/a/pyproject.toml",
-            r#"
-            [project]
-            name = "a"
-            "#,
-        ),
-        (
-            "packages/b/pyproject.toml",
-            r#"
-            [project]
-            name = "b"
-            "#,
-        ),
-    ])?;
-
-    assert_eq!(case.db().workspace().packages(case.db()).len(), 3);
-
-    std::fs::remove_dir_all(case.workspace_path("packages/b").as_std_path())
-        .context("failed to remove package 'b'")?;
-
-    let changes = case.stop_watch();
-
-    case.apply_changes(changes);
-
-    assert_eq!(case.db().workspace().packages(case.db()).len(), 2);
-
-    Ok(())
-}

crates/red_knot_python_semantic/Cargo.toml

@@ -13,8 +13,7 @@ license = { workspace = true }
 [dependencies]
 ruff_db = { workspace = true }
 ruff_index = { workspace = true }
-ruff_python_ast = { workspace = true }
-ruff_python_parser = { workspace = true }
+ruff_python_ast = { workspace = true, features = ["salsa"] }
 ruff_python_stdlib = { workspace = true }
 ruff_source_file = { workspace = true }
 ruff_text_size = { workspace = true }
@@ -33,7 +32,6 @@ thiserror = { workspace = true }
 tracing = { workspace = true }
 rustc-hash = { workspace = true }
 hashbrown = { workspace = true }
-serde = { workspace = true, optional = true }
 smallvec = { workspace = true }
 static_assertions = { workspace = true }
 test-case = { workspace = true }

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

@@ -1,47 +0,0 @@
-# Optional
-
-## Annotation
-
-`typing.Optional` is equivalent to using the type with a None in a Union.
-
-```py
-from typing import Optional
-
-a: Optional[int]
-a1: Optional[bool]
-a2: Optional[Optional[bool]]
-a3: Optional[None]
-
-def f():
-    # revealed: int | None
-    reveal_type(a)
-    # revealed: bool | None
-    reveal_type(a1)
-    # revealed: bool | None
-    reveal_type(a2)
-    # revealed: None
-    reveal_type(a3)
-```
-
-## Assignment
-
-```py
-from typing import Optional
-
-a: Optional[int] = 1
-a = None
-# error: [invalid-assignment] "Object of type `Literal[""]` is not assignable to `int | None`"
-a = ""
-```
-
-## Typing Extensions
-
-```py
-from typing_extensions import Optional
-
-a: Optional[int]
-
-def f():
-    # revealed: int | None
-    reveal_type(a)
-```

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

@@ -1,191 +0,0 @@
-# String annotations
-
-## Simple
-
-```py
-def f() -> "int":
-    return 1
-
-reveal_type(f())  # revealed: int
-```
-
-## Nested
-
-```py
-def f() -> "'int'":
-    return 1
-
-reveal_type(f())  # revealed: int
-```
-
-## Type expression
-
-```py
-def f1() -> "int | str":
-    return 1
-
-def f2() -> "tuple[int, str]":
-    return 1
-
-reveal_type(f1())  # revealed: int | str
-reveal_type(f2())  # revealed: tuple[int, str]
-```
-
-## Partial
-
-```py
-def f() -> tuple[int, "str"]:
-    return 1
-
-reveal_type(f())  # revealed: tuple[int, str]
-```
-
-## Deferred
-
-```py
-def f() -> "Foo":
-    return Foo()
-
-class Foo:
-    pass
-
-reveal_type(f())  # revealed: Foo
-```
-
-## Deferred (undefined)
-
-```py
-# error: [unresolved-reference]
-def f() -> "Foo":
-    pass
-
-reveal_type(f())  # revealed: Unknown
-```
-
-## Partial deferred
-
-```py
-def f() -> int | "Foo":
-    return 1
-
-class Foo:
-    pass
-
-reveal_type(f())  # revealed: int | Foo
-```
-
-## `typing.Literal`
-
-```py
-from typing import Literal
-
-def f1() -> Literal["Foo", "Bar"]:
-    return "Foo"
-
-def f2() -> 'Literal["Foo", "Bar"]':
-    return "Foo"
-
-class Foo:
-    pass
-
-reveal_type(f1())  # revealed: Literal["Foo", "Bar"]
-reveal_type(f2())  # revealed: Literal["Foo", "Bar"]
-```
-
-## Various string kinds
-
-```py
-# error: [annotation-raw-string] "Type expressions cannot use raw string literal"
-def f1() -> r"int":
-    return 1
-
-# error: [annotation-f-string] "Type expressions cannot use f-strings"
-def f2() -> f"int":
-    return 1
-
-# error: [annotation-byte-string] "Type expressions cannot use bytes literal"
-def f3() -> b"int":
-    return 1
-
-def f4() -> "int":
-    return 1
-
-# error: [annotation-implicit-concat] "Type expressions cannot span multiple string literals"
-def f5() -> "in" "t":
-    return 1
-
-# error: [annotation-escape-character] "Type expressions cannot contain escape characters"
-def f6() -> "\N{LATIN SMALL LETTER I}nt":
-    return 1
-
-# error: [annotation-escape-character] "Type expressions cannot contain escape characters"
-def f7() -> "\x69nt":
-    return 1
-
-def f8() -> """int""":
-    return 1
-
-# error: [annotation-byte-string] "Type expressions cannot use bytes literal"
-def f9() -> "b'int'":
-    return 1
-
-reveal_type(f1())  # revealed: Unknown
-reveal_type(f2())  # revealed: Unknown
-reveal_type(f3())  # revealed: Unknown
-reveal_type(f4())  # revealed: int
-reveal_type(f5())  # revealed: Unknown
-reveal_type(f6())  # revealed: Unknown
-reveal_type(f7())  # revealed: Unknown
-reveal_type(f8())  # revealed: int
-reveal_type(f9())  # revealed: Unknown
-```
-
-## Various string kinds in `typing.Literal`
-
-```py
-from typing import Literal
-
-def f() -> Literal["a", r"b", b"c", "d" "e", "\N{LATIN SMALL LETTER F}", "\x67", """h"""]:
-    return "normal"
-
-reveal_type(f())  # revealed: Literal["a", "b", "de", "f", "g", "h"] | Literal[b"c"]
-```
-
-## Class variables
-
-```py
-MyType = int
-
-class Aliases:
-    MyType = str
-
-    forward: "MyType"
-    not_forward: MyType
-
-reveal_type(Aliases.forward)  # revealed: str
-reveal_type(Aliases.not_forward)  # revealed: str
-```
-
-## Annotated assignment
-
-```py
-a: "int" = 1
-b: "'int'" = 1
-c: "Foo"
-# error: [invalid-assignment] "Object of type `Literal[1]` is not assignable to `Foo`"
-d: "Foo" = 1
-
-class Foo:
-    pass
-
-c = Foo()
-
-reveal_type(a)  # revealed: Literal[1]
-reveal_type(b)  # revealed: Literal[1]
-reveal_type(c)  # revealed: Foo
-reveal_type(d)  # revealed: Foo
-```
-
-## Parameter
-
-TODO: Add tests once parameter inference is supported

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

@@ -0,0 +1,9 @@
+# String annotations
+
+```py
+def f() -> "int":
+    return 1
+
+# TODO: We do not support string annotations, but we should not panic if we encounter them
+reveal_type(f())  # revealed: @Todo
+```

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

@@ -110,29 +110,3 @@ c: builtins.tuple[builtins.tuple[builtins.int, builtins.int], builtins.int] = ((
 # error: [invalid-assignment] "Object of type `Literal["foo"]` is not assignable to `tuple[tuple[int, int], int]`"
 c: builtins.tuple[builtins.tuple[builtins.int, builtins.int], builtins.int] = "foo"
 ```
-
-## Future annotations are deferred
-
-```py
-from __future__ import annotations
-
-x: Foo
-
-class Foo:
-    pass
-
-x = Foo()
-reveal_type(x)  # revealed: Foo
-```
-
-## Annotations in stub files are deferred
-
-```pyi path=main.pyi
-x: Foo
-
-class Foo:
-    pass
-
-x = Foo()
-reveal_type(x)  # revealed: Foo
-```

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

@@ -35,7 +35,6 @@ class C:
     if flag:
         x = 2
 
-# error: [possibly-unbound-attribute] "Attribute `x` on type `Literal[C]` is possibly unbound"
 reveal_type(C.x)  # revealed: Literal[2]
 reveal_type(C.y)  # revealed: Literal[1]
 ```

crates/red_knot_python_semantic/resources/mdtest/attributes.md

@@ -9,21 +9,14 @@ def bool_instance() -> bool:
 flag = bool_instance()
 
 if flag:
-    class C1:
+    class C:
         x = 1
 
 else:
-    class C1:
+    class C:
         x = 2
 
-class C2:
-    if flag:
-        x = 3
-    else:
-        x = 4
-
-reveal_type(C1.x)  # revealed: Literal[1, 2]
-reveal_type(C2.x)  # revealed: Literal[3, 4]
+reveal_type(C.x)  # revealed: Literal[1, 2]
 ```
 
 ## Inherited attributes
@@ -60,77 +53,3 @@ reveal_type(A.__mro__)
 # `E` is earlier in the MRO than `F`, so we should use the type of `E.X`
 reveal_type(A.X)  # revealed: Literal[42]
 ```
-
-## Unions with possibly unbound paths
-
-### Definite boundness within a class
-
-In this example, the `x` attribute is not defined in the `C2` element of the union:
-
-```py
-def bool_instance() -> bool:
-    return True
-
-class C1:
-    x = 1
-
-class C2: ...
-
-class C3:
-    x = 3
-
-flag1 = bool_instance()
-flag2 = bool_instance()
-
-C = C1 if flag1 else C2 if flag2 else C3
-
-# error: [possibly-unbound-attribute] "Attribute `x` on type `Literal[C1, C2, C3]` is possibly unbound"
-reveal_type(C.x)  # revealed: Literal[1, 3]
-```
-
-### Possibly-unbound within a class
-
-We raise the same diagnostic if the attribute is possibly-unbound in at least one element of the
-union:
-
-```py
-def bool_instance() -> bool:
-    return True
-
-class C1:
-    x = 1
-
-class C2:
-    if bool_instance():
-        x = 2
-
-class C3:
-    x = 3
-
-flag1 = bool_instance()
-flag2 = bool_instance()
-
-C = C1 if flag1 else C2 if flag2 else C3
-
-# error: [possibly-unbound-attribute] "Attribute `x` on type `Literal[C1, C2, C3]` is possibly unbound"
-reveal_type(C.x)  # revealed: Literal[1, 2, 3]
-```
-
-## Unions with all paths unbound
-
-If the symbol is unbound in all elements of the union, we detect that:
-
-```py
-def bool_instance() -> bool:
-    return True
-
-class C1: ...
-class C2: ...
-
-flag = bool_instance()
-
-C = C1 if flag else C2
-
-# error: [unresolved-attribute] "Type `Literal[C1, C2]` has no attribute `x`"
-reveal_type(C.x)  # revealed: Unknown
-```

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

@@ -18,58 +18,3 @@ class Unit: ...
 b = Unit()(3.0)  # error: "Object of type `Unit` is not callable"
 reveal_type(b)  # revealed: Unknown
 ```
-
-## Possibly unbound `__call__` method
-
-```py
-def flag() -> bool: ...
-
-class PossiblyNotCallable:
-    if flag():
-        def __call__(self) -> int: ...
-
-a = PossiblyNotCallable()
-result = a()  # error: "Object of type `PossiblyNotCallable` is not callable (possibly unbound `__call__` method)"
-reveal_type(result)  # revealed: int
-```
-
-## Possibly unbound callable
-
-```py
-def flag() -> bool: ...
-
-if flag():
-    class PossiblyUnbound:
-        def __call__(self) -> int: ...
-
-# error: [possibly-unresolved-reference]
-a = PossiblyUnbound()
-reveal_type(a())  # revealed: int
-```
-
-## Non-callable `__call__`
-
-```py
-class NonCallable:
-    __call__ = 1
-
-a = NonCallable()
-# error: "Object of type `NonCallable` is not callable"
-reveal_type(a())  # revealed: Unknown
-```
-
-## Possibly non-callable `__call__`
-
-```py
-def flag() -> bool: ...
-
-class NonCallable:
-    if flag():
-        __call__ = 1
-    else:
-        def __call__(self) -> int: ...
-
-a = NonCallable()
-# error: "Object of type `Literal[1] | Literal[__call__]` is not callable (due to union element `Literal[1]`)"
-reveal_type(a())  # revealed: Unknown | int
-```

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

@@ -19,15 +19,6 @@ async def get_int_async() -> int:
 reveal_type(get_int_async())  # revealed: @Todo
 ```
 
-## Generic
-
-```py
-def get_int[T]() -> int:
-    return 42
-
-reveal_type(get_int())  # revealed: int
-```
-
 ## Decorated
 
 ```py
@@ -53,16 +44,3 @@ reveal_type(bar())  # revealed: @Todo
 nonsense = 123
 x = nonsense()  # error: "Object of type `Literal[123]` is not callable"
 ```
-
-## Potentially unbound function
-
-```py
-def flag() -> bool: ...
-
-if flag():
-    def foo() -> int:
-        return 42
-
-# error: [possibly-unresolved-reference]
-reveal_type(foo())  # revealed: int
-```

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

@@ -1,155 +0,0 @@
-# Comparison: Intersections
-
-## Positive contributions
-
-If we have an intersection type `A & B` and we get a definitive true/false answer for one of the
-types, we can infer that the result for the intersection type is also true/false:
-
-```py
-class Base: ...
-
-class Child1(Base):
-    def __eq__(self, other) -> Literal[True]:
-        return True
-
-class Child2(Base): ...
-
-def get_base() -> Base: ...
-
-x = get_base()
-c1 = Child1()
-
-# Create an intersection type through narrowing:
-if isinstance(x, Child1):
-    if isinstance(x, Child2):
-        reveal_type(x)  # revealed: Child1 & Child2
-
-        reveal_type(x == 1)  # revealed: Literal[True]
-
-        # Other comparison operators fall back to the base type:
-        reveal_type(x > 1)  # revealed: bool
-        reveal_type(x is c1)  # revealed: bool
-```
-
-## Negative contributions
-
-Negative contributions to the intersection type only allow simplifications in a few special cases
-(equality and identity comparisons).
-
-### Equality comparisons
-
-#### Literal strings
-
-```py
-x = "x" * 1_000_000_000
-y = "y" * 1_000_000_000
-reveal_type(x)  # revealed: LiteralString
-
-if x != "abc":
-    reveal_type(x)  # revealed: LiteralString & ~Literal["abc"]
-
-    reveal_type(x == "abc")  # revealed: Literal[False]
-    reveal_type("abc" == x)  # revealed: Literal[False]
-    reveal_type(x == "something else")  # revealed: bool
-    reveal_type("something else" == x)  # revealed: bool
-
-    reveal_type(x != "abc")  # revealed: Literal[True]
-    reveal_type("abc" != x)  # revealed: Literal[True]
-    reveal_type(x != "something else")  # revealed: bool
-    reveal_type("something else" != x)  # revealed: bool
-
-    reveal_type(x == y)  # revealed: bool
-    reveal_type(y == x)  # revealed: bool
-    reveal_type(x != y)  # revealed: bool
-    reveal_type(y != x)  # revealed: bool
-
-    reveal_type(x >= "abc")  # revealed: bool
-    reveal_type("abc" >= x)  # revealed: bool
-
-    reveal_type(x in "abc")  # revealed: bool
-    reveal_type("abc" in x)  # revealed: bool
-```
-
-#### Integers
-
-```py
-def get_int() -> int: ...
-
-x = get_int()
-
-if x != 1:
-    reveal_type(x)  # revealed: int & ~Literal[1]
-
-    reveal_type(x != 1)  # revealed: Literal[True]
-    reveal_type(x != 2)  # revealed: bool
-
-    reveal_type(x == 1)  # revealed: Literal[False]
-    reveal_type(x == 2)  # revealed: bool
-```
-
-### Identity comparisons
-
-```py
-class A: ...
-
-def get_object() -> object: ...
-
-o = object()
-
-a = A()
-n = None
-
-if o is not None:
-    reveal_type(o)  # revealed: object & ~None
-
-    reveal_type(o is n)  # revealed: Literal[False]
-    reveal_type(o is not n)  # revealed: Literal[True]
-```
-
-## Diagnostics
-
-### Unsupported operators for positive contributions
-
-Raise an error if any of the positive contributions to the intersection type are unsupported for the
-given operator:
-
-```py
-class Container:
-    def __contains__(self, x) -> bool: ...
-
-class NonContainer: ...
-
-def get_object() -> object: ...
-
-x = get_object()
-
-if isinstance(x, Container):
-    if isinstance(x, NonContainer):
-        reveal_type(x)  # revealed: Container & NonContainer
-
-        # error: [unsupported-operator] "Operator `in` is not supported for types `int` and `NonContainer`"
-        reveal_type(2 in x)  # revealed: bool
-```
-
-### Unsupported operators for negative contributions
-
-Do *not* raise an error if any of the negative contributions to the intersection type are
-unsupported for the given operator:
-
-```py
-class Container:
-    def __contains__(self, x) -> bool: ...
-
-class NonContainer: ...
-
-def get_object() -> object: ...
-
-x = get_object()
-
-if isinstance(x, Container):
-    if not isinstance(x, NonContainer):
-        reveal_type(x)  # revealed: Container & ~NonContainer
-
-        # No error here!
-        reveal_type(2 in x)  # revealed: bool
-```

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

@@ -41,10 +41,11 @@ except EXCEPTIONS as f:
 ## Dynamic exception types
 
 ```py
+# TODO: we should not emit these `call-possibly-unbound-method` errors for `tuple.__class_getitem__`
 def foo(
     x: type[AttributeError],
-    y: tuple[type[OSError], type[RuntimeError]],
-    z: tuple[type[BaseException], ...],
+    y: tuple[type[OSError], type[RuntimeError]],  # error: [call-possibly-unbound-method]
+    z: tuple[type[BaseException], ...],  # error: [call-possibly-unbound-method]
 ):
     try:
         help()

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

@@ -1,28 +0,0 @@
-# Attribute access
-
-## Boundness
-
-```py
-def flag() -> bool: ...
-
-class A:
-    always_bound = 1
-
-    if flag():
-        union = 1
-    else:
-        union = "abc"
-
-    if flag():
-        possibly_unbound = "abc"
-
-reveal_type(A.always_bound)  # revealed: Literal[1]
-
-reveal_type(A.union)  # revealed: Literal[1] | Literal["abc"]
-
-# error: [possibly-unbound-attribute] "Attribute `possibly_unbound` on type `Literal[A]` is possibly unbound"
-reveal_type(A.possibly_unbound)  # revealed: Literal["abc"]
-
-# error: [unresolved-attribute] "Type `Literal[A]` has no attribute `non_existent`"
-reveal_type(A.non_existent)  # revealed: Unknown
-```

crates/red_knot_python_semantic/resources/mdtest/generics.md

@@ -6,9 +6,13 @@ Basic PEP 695 generics
 
 ```py
 class MyBox[T]:
+    # TODO: `T` is defined here
+    # error: [unresolved-reference] "Name `T` used when not defined"
     data: T
     box_model_number = 695
 
+    # TODO: `T` is defined here
+    # error: [unresolved-reference] "Name `T` used when not defined"
     def __init__(self, data: T):
         self.data = data
 
@@ -27,12 +31,17 @@ reveal_type(MyBox.box_model_number)  # revealed: Literal[695]
 
 ```py
 class MyBox[T]:
+    # TODO: `T` is defined here
+    # error: [unresolved-reference] "Name `T` used when not defined"
     data: T
 
+    # TODO: `T` is defined here
+    # error: [unresolved-reference] "Name `T` used when not defined"
     def __init__(self, data: T):
         self.data = data
 
-# TODO not error on the subscripting
+# TODO not error on the subscripting or the use of type param
+# error: [unresolved-reference] "Name `T` used when not defined"
 # error: [non-subscriptable]
 class MySecureBox[T](MyBox[T]): ...
 
@@ -57,55 +66,3 @@ class S[T](Seq[S]): ...  # error: [non-subscriptable]
 
 reveal_type(S)  # revealed: Literal[S]
 ```
-
-## Type params
-
-A PEP695 type variable defines a value of type `typing.TypeVar` with attributes `__name__`,
-`__bounds__`, `__constraints__`, and `__default__` (the latter three all lazily evaluated):
-
-```py
-def f[T, U: A, V: (A, B), W = A, X: A = A1]():
-    reveal_type(T)  # revealed: T
-    reveal_type(T.__name__)  # revealed: Literal["T"]
-    reveal_type(T.__bound__)  # revealed: None
-    reveal_type(T.__constraints__)  # revealed: tuple[()]
-    reveal_type(T.__default__)  # revealed: NoDefault
-
-    reveal_type(U)  # revealed: U
-    reveal_type(U.__name__)  # revealed: Literal["U"]
-    reveal_type(U.__bound__)  # revealed: type[A]
-    reveal_type(U.__constraints__)  # revealed: tuple[()]
-    reveal_type(U.__default__)  # revealed: NoDefault
-
-    reveal_type(V)  # revealed: V
-    reveal_type(V.__name__)  # revealed: Literal["V"]
-    reveal_type(V.__bound__)  # revealed: None
-    reveal_type(V.__constraints__)  # revealed: tuple[type[A], type[B]]
-    reveal_type(V.__default__)  # revealed: NoDefault
-
-    reveal_type(W)  # revealed: W
-    reveal_type(W.__name__)  # revealed: Literal["W"]
-    reveal_type(W.__bound__)  # revealed: None
-    reveal_type(W.__constraints__)  # revealed: tuple[()]
-    reveal_type(W.__default__)  # revealed: type[A]
-
-    reveal_type(X)  # revealed: X
-    reveal_type(X.__name__)  # revealed: Literal["X"]
-    reveal_type(X.__bound__)  # revealed: type[A]
-    reveal_type(X.__constraints__)  # revealed: tuple[()]
-    reveal_type(X.__default__)  # revealed: type[A1]
-
-class A: ...
-class B: ...
-class A1(A): ...
-```
-
-## Minimum two constraints
-
-A typevar with less than two constraints emits a diagnostic and is treated as unconstrained:
-
-```py
-# error: [invalid-typevar-constraints] "TypeVar must have at least two constrained types"
-def f[T: (int,)]():
-    reveal_type(T.__constraints__)  # revealed: tuple[()]
-```

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

@@ -21,7 +21,6 @@ reveal_type(y)
 ```
 
 ```py
-# error: [possibly-unbound-import] "Member `y` of module `maybe_unbound` is possibly unbound"
 from maybe_unbound import x, y
 
 reveal_type(x)  # revealed: Literal[3]
@@ -51,7 +50,6 @@ reveal_type(y)
 Importing an annotated name prefers the declared type over the inferred type:
 
 ```py
-# error: [possibly-unbound-import] "Member `y` of module `maybe_unbound_annotated` is possibly unbound"
 from maybe_unbound_annotated import x, y
 
 reveal_type(x)  # revealed: Literal[3]

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

@@ -51,8 +51,6 @@ invalid1: Literal[3 + 4]
 invalid2: Literal[4 + 3j]
 # error: [invalid-literal-parameter]
 invalid3: Literal[(3, 4)]
-
-hello = "hello"
 invalid4: Literal[
     1 + 2,  # error: [invalid-literal-parameter]
     "foo",

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

@@ -238,7 +238,7 @@ class Test:
 def coinflip() -> bool:
     return True
 
-# error: [not-iterable] "Object of type `Test | Literal[42]` is not iterable because its `__iter__` method is possibly unbound"
+# TODO: we should emit a diagnostic here (it might not be iterable)
 for x in Test() if coinflip() else 42:
     reveal_type(x)  # revealed: int
 ```

crates/red_knot_python_semantic/resources/mdtest/metaclass.md

@@ -65,7 +65,7 @@ class M2(type): ...
 class A(metaclass=M1): ...
 class B(metaclass=M2): ...
 
-# error: [conflicting-metaclass] "The metaclass of a derived class (`C`) must be a subclass of the metaclasses of all its bases, but `M1` (metaclass of base class `A`) and `M2` (metaclass of base class `B`) have no subclass relationship"
+# error: [conflicting-metaclass] "The metaclass of a derived class (`C`) must be a subclass of the metaclasses of all its bases, but `M1` and `M2` have no subclass relationship"
 class C(A, B): ...
 
 reveal_type(C.__class__)  # revealed: Unknown
@@ -82,7 +82,7 @@ class M1(type): ...
 class M2(type): ...
 class A(metaclass=M1): ...
 
-# error: [conflicting-metaclass] "The metaclass of a derived class (`B`) must be a subclass of the metaclasses of all its bases, but `M2` (metaclass of `B`) and `M1` (metaclass of base class `A`) have no subclass relationship"
+# error: [conflicting-metaclass] "The metaclass of a derived class (`B`) must be a subclass of the metaclasses of all its bases, but `M2` and `M1` have no subclass relationship"
 class B(A, metaclass=M2): ...
 
 reveal_type(B.__class__)  # revealed: Unknown
@@ -126,7 +126,7 @@ class A(metaclass=M1): ...
 class B(metaclass=M2): ...
 class C(metaclass=M12): ...
 
-# error: [conflicting-metaclass] "The metaclass of a derived class (`D`) must be a subclass of the metaclasses of all its bases, but `M1` (metaclass of base class `A`) and `M2` (metaclass of base class `B`) have no subclass relationship"
+# error: [conflicting-metaclass] "The metaclass of a derived class (`D`) must be a subclass of the metaclasses of all its bases, but `M1` and `M2` have no subclass relationship"
 class D(A, B, C): ...
 
 reveal_type(D.__class__)  # revealed: Unknown

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

@@ -1,247 +0,0 @@
-# Narrowing for `issubclass` checks
-
-Narrowing for `issubclass(class, classinfo)` expressions.
-
-## `classinfo` is a single type
-
-### Basic example
-
-```py
-def flag() -> bool: ...
-
-t = int if flag() else str
-
-if issubclass(t, bytes):
-    reveal_type(t)  # revealed: Never
-
-if issubclass(t, object):
-    reveal_type(t)  # revealed: Literal[int, str]
-
-if issubclass(t, int):
-    reveal_type(t)  # revealed: Literal[int]
-else:
-    reveal_type(t)  # revealed: Literal[str]
-
-if issubclass(t, str):
-    reveal_type(t)  # revealed: Literal[str]
-    if issubclass(t, int):
-        reveal_type(t)  # revealed: Never
-```
-
-### Proper narrowing in `elif` and `else` branches
-
-```py
-def flag() -> bool: ...
-
-t = int if flag() else str if flag() else bytes
-
-if issubclass(t, int):
-    reveal_type(t)  # revealed: Literal[int]
-else:
-    reveal_type(t)  # revealed: Literal[str, bytes]
-
-if issubclass(t, int):
-    reveal_type(t)  # revealed: Literal[int]
-elif issubclass(t, str):
-    reveal_type(t)  # revealed: Literal[str]
-else:
-    reveal_type(t)  # revealed: Literal[bytes]
-```
-
-### Multiple derived classes
-
-```py
-class Base: ...
-class Derived1(Base): ...
-class Derived2(Base): ...
-class Unrelated: ...
-
-def flag() -> bool: ...
-
-t1 = Derived1 if flag() else Derived2
-
-if issubclass(t1, Base):
-    reveal_type(t1)  # revealed: Literal[Derived1, Derived2]
-
-if issubclass(t1, Derived1):
-    reveal_type(t1)  # revealed: Literal[Derived1]
-else:
-    reveal_type(t1)  # revealed: Literal[Derived2]
-
-t2 = Derived1 if flag() else Base
-
-if issubclass(t2, Base):
-    reveal_type(t2)  # revealed: Literal[Derived1, Base]
-
-t3 = Derived1 if flag() else Unrelated
-
-if issubclass(t3, Base):
-    reveal_type(t3)  # revealed: Literal[Derived1]
-else:
-    reveal_type(t3)  # revealed: Literal[Unrelated]
-```
-
-### Narrowing for non-literals
-
-```py
-class A: ...
-class B: ...
-
-def get_class() -> type[object]: ...
-
-t = get_class()
-
-if issubclass(t, A):
-    reveal_type(t)  # revealed: type[A]
-    if issubclass(t, B):
-        reveal_type(t)  # revealed: type[A] & type[B]
-else:
-    reveal_type(t)  # revealed: type[object] & ~type[A]
-```
-
-### Handling of `None`
-
-```py
-# TODO: this error should ideally go away once we (1) understand `sys.version_info` branches,
-# and (2) set the target Python version for this test to 3.10.
-# error: [possibly-unbound-import] "Member `NoneType` of module `types` is possibly unbound"
-from types import NoneType
-
-def flag() -> bool: ...
-
-t = int if flag() else NoneType
-
-if issubclass(t, NoneType):
-    reveal_type(t)  # revealed: Literal[NoneType]
-
-if issubclass(t, type(None)):
-    # TODO: this should be just `Literal[NoneType]`
-    reveal_type(t)  # revealed: Literal[int, NoneType]
-```
-
-## `classinfo` contains multiple types
-
-### (Nested) tuples of types
-
-```py
-class Unrelated: ...
-
-def flag() -> bool: ...
-
-t = int if flag() else str if flag() else bytes
-
-if issubclass(t, (int, (Unrelated, (bytes,)))):
-    reveal_type(t)  # revealed: Literal[int, bytes]
-else:
-    reveal_type(t)  # revealed: Literal[str]
-```
-
-## Special cases
-
-### Emit a diagnostic if the first argument is of wrong type
-
-#### Too wide
-
-`type[object]` is a subtype of `object`, but not every `object` can be passed as the first argument
-to `issubclass`:
-
-```py
-class A: ...
-
-def get_object() -> object: ...
-
-t = get_object()
-
-# TODO: we should emit a diagnostic here
-if issubclass(t, A):
-    reveal_type(t)  # revealed: type[A]
-```
-
-#### Wrong
-
-`Literal[1]` and `type` are entirely disjoint, so the inferred type of `Literal[1] & type[int]` is
-eagerly simplified to `Never` as a result of the type narrowing in the `if issubclass(t, int)`
-branch:
-
-```py
-t = 1
-
-# TODO: we should emit a diagnostic here
-if issubclass(t, int):
-    reveal_type(t)  # revealed: Never
-```
-
-### Do not use custom `issubclass` for narrowing
-
-```py
-def issubclass(c, ci):
-    return True
-
-def flag() -> bool: ...
-
-t = int if flag() else str
-if issubclass(t, int):
-    reveal_type(t)  # revealed: Literal[int, str]
-```
-
-### Do support narrowing if `issubclass` is aliased
-
-```py
-issubclass_alias = issubclass
-
-def flag() -> bool: ...
-
-t = int if flag() else str
-if issubclass_alias(t, int):
-    reveal_type(t)  # revealed: Literal[int]
-```
-
-### Do support narrowing if `issubclass` is imported
-
-```py
-from builtins import issubclass as imported_issubclass
-
-def flag() -> bool: ...
-
-t = int if flag() else str
-if imported_issubclass(t, int):
-    reveal_type(t)  # revealed: Literal[int]
-```
-
-### Do not narrow if second argument is not a proper `classinfo` argument
-
-```py
-from typing import Any
-
-def flag() -> bool: ...
-
-t = int if flag() else str
-
-# TODO: this should cause us to emit a diagnostic during
-# type checking
-if issubclass(t, "str"):
-    reveal_type(t)  # revealed: Literal[int, str]
-
-# TODO: this should cause us to emit a diagnostic during
-# type checking
-if issubclass(t, (bytes, "str")):
-    reveal_type(t)  # revealed: Literal[int, str]
-
-# TODO: this should cause us to emit a diagnostic during
-# type checking
-if issubclass(t, Any):
-    reveal_type(t)  # revealed: Literal[int, str]
-```
-
-### Do not narrow if there are keyword arguments
-
-```py
-def flag() -> bool: ...
-
-t = int if flag() else str
-
-# TODO: this should cause us to emit a diagnostic
-# (`issubclass` has no `foo` parameter)
-if issubclass(t, int, foo="bar"):
-    reveal_type(t)  # revealed: Literal[int, str]
-```

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

@@ -1,152 +0,0 @@
-# Narrowing for checks involving `type(x)`
-
-## `type(x) is C`
-
-```py
-class A: ...
-class B: ...
-
-def get_a_or_b() -> A | B:
-    return A()
-
-x = get_a_or_b()
-
-if type(x) is A:
-    reveal_type(x)  # revealed: A
-else:
-    # It would be wrong to infer `B` here. The type
-    # of `x` could be a subclass of `A`, so we need
-    # to infer the full union type:
-    reveal_type(x)  # revealed: A | B
-```
-
-## `type(x) is not C`
-
-```py
-class A: ...
-class B: ...
-
-def get_a_or_b() -> A | B:
-    return A()
-
-x = get_a_or_b()
-
-if type(x) is not A:
-    # Same reasoning as above: no narrowing should occur here.
-    reveal_type(x)  # revealed: A | B
-else:
-    reveal_type(x)  # revealed: A
-```
-
-## `type(x) == C`, `type(x) != C`
-
-No narrowing can occur for equality comparisons, since there might be a custom `__eq__`
-implementation on the metaclass.
-
-TODO: Narrowing might be possible in some cases where the classes themselves are `@final` or their
-metaclass is `@final`.
-
-```py
-class IsEqualToEverything(type):
-    def __eq__(cls, other):
-        return True
-
-class A(metaclass=IsEqualToEverything): ...
-class B(metaclass=IsEqualToEverything): ...
-
-def get_a_or_b() -> A | B:
-    return B()
-
-x = get_a_or_b()
-
-if type(x) == A:
-    reveal_type(x)  # revealed: A | B
-
-if type(x) != A:
-    reveal_type(x)  # revealed: A | B
-```
-
-## No narrowing for custom `type` callable
-
-```py
-class A: ...
-class B: ...
-
-def type(x):
-    return int
-
-def get_a_or_b() -> A | B:
-    return A()
-
-x = get_a_or_b()
-
-if type(x) is A:
-    reveal_type(x)  # revealed: A | B
-else:
-    reveal_type(x)  # revealed: A | B
-```
-
-## No narrowing for multiple arguments
-
-No narrowing should occur if `type` is used to dynamically create a class:
-
-```py
-def get_str_or_int() -> str | int:
-    return "test"
-
-x = get_str_or_int()
-
-if type(x, (), {}) is str:
-    reveal_type(x)  # revealed: str | int
-else:
-    reveal_type(x)  # revealed: str | int
-```
-
-## No narrowing for keyword arguments
-
-`type` can't be used with a keyword argument:
-
-```py
-def get_str_or_int() -> str | int:
-    return "test"
-
-x = get_str_or_int()
-
-# TODO: we could issue a diagnostic here
-if type(object=x) is str:
-    reveal_type(x)  # revealed: str | int
-```
-
-## Narrowing if `type` is aliased
-
-```py
-class A: ...
-class B: ...
-
-alias_for_type = type
-
-def get_a_or_b() -> A | B:
-    return A()
-
-x = get_a_or_b()
-
-if alias_for_type(x) is A:
-    reveal_type(x)  # revealed: A
-```
-
-## Limitations
-
-```py
-class Base: ...
-class Derived(Base): ...
-
-def get_base() -> Base:
-    return Base()
-
-x = get_base()
-
-if type(x) is Base:
-    # Ideally, this could be narrower, but there is now way to
-    # express a constraint like `Base & ~ProperSubtypeOf[Base]`.
-    reveal_type(x)  # revealed: Base
-```

crates/red_knot_python_semantic/resources/mdtest/regression/14334_diagnostics_in_wrong_file.md

@@ -1,13 +0,0 @@
-# Regression test for #14334
-
-Regression test for [this issue](https://github.com/astral-sh/ruff/issues/14334).
-
-```py path=base.py
-# error: [invalid-base]
-class Base(2): ...
-```
-
-```py path=a.py
-# No error here
-from base import Base
-```

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

@@ -74,7 +74,6 @@ we're dealing with:
 ```py path=__getattr__.py
 import typing
 
-# error: [unresolved-attribute]
 reveal_type(typing.__getattr__)  # revealed: Unknown
 ```
 

crates/red_knot_python_semantic/resources/mdtest/sys_version_info.md

@@ -1,139 +0,0 @@
-# `sys.version_info`
-
-## The type of `sys.version_info`
-
-The type of `sys.version_info` is `sys._version_info`, at least according to typeshed's stubs (which
-we treat as the single source of truth for the standard library). This is quite a complicated type
-in typeshed, so there are many things we don't fully understand about the type yet; this is the
-source of several TODOs in this test file. Many of these TODOs should be naturally fixed as we
-implement more type-system features in the future.
-
-```py
-import sys
-
-reveal_type(sys.version_info)  # revealed: _version_info
-```
-
-## Literal types from comparisons
-
-Comparing `sys.version_info` with a 2-element tuple of literal integers always produces a `Literal`
-type:
-
-```py
-import sys
-
-reveal_type(sys.version_info >= (3, 9))  # revealed: Literal[True]
-reveal_type((3, 9) <= sys.version_info)  # revealed: Literal[True]
-
-reveal_type(sys.version_info > (3, 9))  # revealed: Literal[True]
-reveal_type((3, 9) < sys.version_info)  # revealed: Literal[True]
-
-reveal_type(sys.version_info < (3, 9))  # revealed: Literal[False]
-reveal_type((3, 9) > sys.version_info)  # revealed: Literal[False]
-
-reveal_type(sys.version_info <= (3, 9))  # revealed: Literal[False]
-reveal_type((3, 9) >= sys.version_info)  # revealed: Literal[False]
-
-reveal_type(sys.version_info == (3, 9))  # revealed: Literal[False]
-reveal_type((3, 9) == sys.version_info)  # revealed: Literal[False]
-
-reveal_type(sys.version_info != (3, 9))  # revealed: Literal[True]
-reveal_type((3, 9) != sys.version_info)  # revealed: Literal[True]
-```
-
-## Non-literal types from comparisons
-
-Comparing `sys.version_info` with tuples of other lengths will sometimes produce `Literal` types,
-sometimes not:
-
-```py
-import sys
-
-reveal_type(sys.version_info >= (3, 9, 1))  # revealed: bool
-reveal_type(sys.version_info >= (3, 9, 1, "final", 0))  # revealed: bool
-
-# TODO: While this won't fail at runtime, the user has probably made a mistake
-# if they're comparing a tuple of length >5 with `sys.version_info`
-# (`sys.version_info` is a tuple of length 5). It might be worth
-# emitting a lint diagnostic of some kind warning them about the probable error?
-reveal_type(sys.version_info >= (3, 9, 1, "final", 0, 5))  # revealed: bool
-
-# TODO: this should be `Literal[False]`; see #14279
-reveal_type(sys.version_info == (3, 9, 1, "finallllll", 0))  # revealed: bool
-```
-
-## Imports and aliases
-
-Comparisons with `sys.version_info` still produce literal types, even if the symbol is aliased to
-another name:
-
-```py
-from sys import version_info
-from sys import version_info as foo
-
-reveal_type(version_info >= (3, 9))  # revealed: Literal[True]
-reveal_type(foo >= (3, 9))  # revealed: Literal[True]
-
-bar = version_info
-reveal_type(bar >= (3, 9))  # revealed: Literal[True]
-```
-
-## Non-stdlib modules named `sys`
-
-Only comparisons with the symbol `version_info` from the `sys` module produce literal types:
-
-```py path=package/__init__.py
-```
-
-```py path=package/sys.py
-version_info: tuple[int, int] = (4, 2)
-```
-
-```py path=package/script.py
-from .sys import version_info
-
-reveal_type(version_info >= (3, 9))  # revealed: bool
-```
-
-## Accessing fields by name
-
-The fields of `sys.version_info` can be accessed by name:
-
-```py path=a.py
-import sys
-
-reveal_type(sys.version_info.major >= 3)  # revealed: Literal[True]
-reveal_type(sys.version_info.minor >= 9)  # revealed: Literal[True]
-reveal_type(sys.version_info.minor >= 10)  # revealed: Literal[False]
-```
-
-But the `micro`, `releaselevel` and `serial` fields are inferred as `@Todo` until we support
-properties on instance types:
-
-```py path=b.py
-import sys
-
-reveal_type(sys.version_info.micro)  # revealed: @Todo
-reveal_type(sys.version_info.releaselevel)  # revealed: @Todo
-reveal_type(sys.version_info.serial)  # revealed: @Todo
-```
-
-## Accessing fields by index/slice
-
-The fields of `sys.version_info` can be accessed by index or by slice:
-
-```py
-import sys
-
-reveal_type(sys.version_info[0] < 3)  # revealed: Literal[False]
-reveal_type(sys.version_info[1] > 9)  # revealed: Literal[False]
-
-# revealed: tuple[Literal[3], Literal[9], int, Literal["alpha", "beta", "candidate", "final"], int]
-reveal_type(sys.version_info[:5])
-
-reveal_type(sys.version_info[:2] >= (3, 9))  # revealed: Literal[True]
-reveal_type(sys.version_info[0:2] >= (3, 10))  # revealed: Literal[False]
-reveal_type(sys.version_info[:3] >= (3, 10, 1))  # revealed: Literal[False]
-reveal_type(sys.version_info[3] == "final")  # revealed: bool
-reveal_type(sys.version_info[3] == "finalllllll")  # revealed: Literal[False]
-```

crates/red_knot_python_semantic/resources/mdtest/unary/instance.md

@@ -1,6 +1,4 @@
-# Invert, UAdd, USub
-
-## Instance
+# Unary Operations
 
 ```py
 from typing import Literal

crates/red_knot_python_semantic/resources/mdtest/unary/not.md

@@ -10,6 +10,8 @@ reveal_type(not not None)  # revealed: Literal[False]
 ## Function
 
 ```py
+from typing import reveal_type
+
 def f():
     return 1
 
@@ -113,101 +115,3 @@ reveal_type(not ())  # revealed: Literal[True]
 reveal_type(not ("hello",))  # revealed: Literal[False]
 reveal_type(not (1, "hello"))  # revealed: Literal[False]
 ```
-
-## Instance
-
-Not operator is inferred based on
-<https://docs.python.org/3/library/stdtypes.html#truth-value-testing>. An instance is True or False
-if the `__bool__` method says so.
-
-At runtime, the `__len__` method is a fallback for `__bool__`, but we can't make use of that. If we
-have a class that defines `__len__` but not `__bool__`, it is possible that any subclass could add a
-`__bool__` method that would invalidate whatever conclusion we drew from `__len__`. So instances of
-classes without a `__bool__` method, with or without `__len__`, must be inferred as unknown
-truthiness.
-
-```py
-class AlwaysTrue:
-    def __bool__(self) -> Literal[True]:
-        return True
-
-# revealed: Literal[False]
-reveal_type(not AlwaysTrue())
-
-class AlwaysFalse:
-    def __bool__(self) -> Literal[False]:
-        return False
-
-# revealed: Literal[True]
-reveal_type(not AlwaysFalse())
-
-# We don't get into a cycle if someone sets their `__bool__` method to the `bool` builtin:
-class BoolIsBool:
-    __bool__ = bool
-
-# revealed: bool
-reveal_type(not BoolIsBool())
-
-# At runtime, no `__bool__` and no `__len__` means truthy, but we can't rely on that, because
-# a subclass could add a `__bool__` method.
-class NoBoolMethod: ...
-
-# revealed: bool
-reveal_type(not NoBoolMethod())
-
-# And we can't rely on `__len__` for the same reason: a subclass could add `__bool__`.
-class LenZero:
-    def __len__(self) -> Literal[0]:
-        return 0
-
-# revealed: bool
-reveal_type(not LenZero())
-
-class LenNonZero:
-    def __len__(self) -> Literal[1]:
-        return 1
-
-# revealed: bool
-reveal_type(not LenNonZero())
-
-class WithBothLenAndBool1:
-    def __bool__(self) -> Literal[False]:
-        return False
-
-    def __len__(self) -> Literal[2]:
-        return 2
-
-# revealed: Literal[True]
-reveal_type(not WithBothLenAndBool1())
-
-class WithBothLenAndBool2:
-    def __bool__(self) -> Literal[True]:
-        return True
-
-    def __len__(self) -> Literal[0]:
-        return 0
-
-# revealed: Literal[False]
-reveal_type(not WithBothLenAndBool2())
-
-# TODO: raise diagnostic when __bool__ method is not valid: [unsupported-operator] "Method __bool__ for type `MethodBoolInvalid` should return `bool`, returned type `int`"
-# https://docs.python.org/3/reference/datamodel.html#object.__bool__
-class MethodBoolInvalid:
-    def __bool__(self) -> int:
-        return 0
-
-# revealed: bool
-reveal_type(not MethodBoolInvalid())
-
-# Don't trust a possibly-unbound `__bool__` method:
-def get_flag() -> bool:
-    return True
-
-class PossiblyUnboundBool:
-    if get_flag():
-        def __bool__(self) -> Literal[False]:
-            return False
-
-# revealed: bool
-reveal_type(not PossiblyUnboundBool())
-```

crates/red_knot_python_semantic/src/module_resolver/typeshed.rs

@@ -459,11 +459,11 @@ foo: 3.8-   # trailing comment
 ";
         let parsed_versions = TypeshedVersions::from_str(VERSIONS).unwrap();
         assert_eq!(parsed_versions.len(), 3);
-        assert_snapshot!(parsed_versions.to_string(), @r"
+        assert_snapshot!(parsed_versions.to_string(), @r###"
         bar: 2.7-3.10
         bar.baz: 3.1-3.9
         foo: 3.8-
-        "
+        "###
         );
     }
 

crates/red_knot_python_semantic/src/node_key.rs

@@ -1,14 +1,14 @@
-use ruff_python_ast::AnyNodeRef;
+use ruff_python_ast::{AnyNodeRef, NodeKind};
+use ruff_text_size::{Ranged, TextRange};
 
 /// Compact key for a node for use in a hash map.
 ///
-/// Stores the memory address of the node, because using the range and the kind
-/// of the node is not enough to uniquely identify them in ASTs resulting from
-/// invalid syntax. For example, parsing the input `for` results in a `StmtFor`
-/// AST node where both the `target` and the `iter` field are `ExprName` nodes
-/// with the same (empty) range `3..3`.
+/// Compares two nodes by their kind and text range.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
-pub(super) struct NodeKey(usize);
+pub(super) struct NodeKey {
+    kind: NodeKind,
+    range: TextRange,
+}
 
 impl NodeKey {
     pub(super) fn from_node<'a, N>(node: N) -> Self
@@ -16,6 +16,9 @@ impl NodeKey {
         N: Into<AnyNodeRef<'a>>,
     {
         let node = node.into();
-        NodeKey(node.as_ptr().as_ptr() as usize)
+        NodeKey {
+            kind: node.kind(),
+            range: node.range(),
+        }
     }
 }

crates/red_knot_python_semantic/src/program.rs

@@ -54,7 +54,6 @@ impl Program {
 }
 
 #[derive(Clone, Debug, Eq, PartialEq)]
-#[cfg_attr(feature = "serde", derive(serde::Serialize))]
 pub struct ProgramSettings {
     pub target_version: PythonVersion,
     pub search_paths: SearchPathSettings,
@@ -62,7 +61,6 @@ pub struct ProgramSettings {
 
 /// Configures the search paths for module resolution.
 #[derive(Eq, PartialEq, Debug, Clone)]
-#[cfg_attr(feature = "serde", derive(serde::Serialize))]
 pub struct SearchPathSettings {
     /// List of user-provided paths that should take first priority in the module resolution.
     /// Examples in other type checkers are mypy's MYPYPATH environment variable,
@@ -93,7 +91,6 @@ impl SearchPathSettings {
 }
 
 #[derive(Debug, Clone, Eq, PartialEq)]
-#[cfg_attr(feature = "serde", derive(serde::Serialize))]
 pub enum SitePackages {
     Derived {
         venv_path: SystemPathBuf,

crates/red_knot_python_semantic/src/python_version.rs

@@ -5,7 +5,6 @@ use std::fmt;
 /// Unlike the `TargetVersion` enums in the CLI crates,
 /// this does not necessarily represent a Python version that we actually support.
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
-#[cfg_attr(feature = "serde", derive(serde::Serialize))]
 pub struct PythonVersion {
     pub major: u8,
     pub minor: u8,
@@ -39,7 +38,7 @@ impl PythonVersion {
 
 impl Default for PythonVersion {
     fn default() -> Self {
-        Self::PY39
+        Self::PY38
     }
 }
 

crates/red_knot_python_semantic/src/semantic_index/ast_ids.rs

@@ -49,50 +49,64 @@ fn ast_ids<'db>(db: &'db dyn Db, scope: ScopeId) -> &'db AstIds {
     semantic_index(db, scope.file(db)).ast_ids(scope.file_scope_id(db))
 }
 
+pub trait HasScopedUseId {
+    /// The type of the ID uniquely identifying the use.
+    type Id: Copy;
+
+    /// Returns the ID that uniquely identifies the use in `scope`.
+    fn scoped_use_id(&self, db: &dyn Db, scope: ScopeId) -> Self::Id;
+}
+
 /// Uniquely identifies a use of a name in a [`crate::semantic_index::symbol::FileScopeId`].
 #[newtype_index]
 pub struct ScopedUseId;
 
-pub trait HasScopedUseId {
-    /// Returns the ID that uniquely identifies the use in `scope`.
-    fn scoped_use_id(&self, db: &dyn Db, scope: ScopeId) -> ScopedUseId;
-}
-
 impl HasScopedUseId for ast::ExprName {
-    fn scoped_use_id(&self, db: &dyn Db, scope: ScopeId) -> ScopedUseId {
+    type Id = ScopedUseId;
+
+    fn scoped_use_id(&self, db: &dyn Db, scope: ScopeId) -> Self::Id {
         let expression_ref = ExpressionRef::from(self);
         expression_ref.scoped_use_id(db, scope)
     }
 }
 
 impl HasScopedUseId for ast::ExpressionRef<'_> {
-    fn scoped_use_id(&self, db: &dyn Db, scope: ScopeId) -> ScopedUseId {
+    type Id = ScopedUseId;
+
+    fn scoped_use_id(&self, db: &dyn Db, scope: ScopeId) -> Self::Id {
         let ast_ids = ast_ids(db, scope);
         ast_ids.use_id(*self)
     }
 }
 
+pub trait HasScopedAstId {
+    /// The type of the ID uniquely identifying the node.
+    type Id: Copy;
+
+    /// Returns the ID that uniquely identifies the node in `scope`.
+    fn scoped_ast_id(&self, db: &dyn Db, scope: ScopeId) -> Self::Id;
+}
+
+impl<T: HasScopedAstId> HasScopedAstId for Box<T> {
+    type Id = <T as HasScopedAstId>::Id;
+
+    fn scoped_ast_id(&self, db: &dyn Db, scope: ScopeId) -> Self::Id {
+        self.as_ref().scoped_ast_id(db, scope)
+    }
+}
+
 /// Uniquely identifies an [`ast::Expr`] in a [`crate::semantic_index::symbol::FileScopeId`].
 #[newtype_index]
 pub struct ScopedExpressionId;
 
-pub trait HasScopedExpressionId {
-    /// Returns the ID that uniquely identifies the node in `scope`.
-    fn scoped_expression_id(&self, db: &dyn Db, scope: ScopeId) -> ScopedExpressionId;
-}
-
-impl<T: HasScopedExpressionId> HasScopedExpressionId for Box<T> {
-    fn scoped_expression_id(&self, db: &dyn Db, scope: ScopeId) -> ScopedExpressionId {
-        self.as_ref().scoped_expression_id(db, scope)
-    }
-}
-
 macro_rules! impl_has_scoped_expression_id {
     ($ty: ty) => {
-        impl HasScopedExpressionId for $ty {
-            fn scoped_expression_id(&self, db: &dyn Db, scope: ScopeId) -> ScopedExpressionId {
+        impl HasScopedAstId for $ty {
+            type Id = ScopedExpressionId;
+
+            fn scoped_ast_id(&self, db: &dyn Db, scope: ScopeId) -> Self::Id {
                 let expression_ref = ExpressionRef::from(self);
-                expression_ref.scoped_expression_id(db, scope)
+                expression_ref.scoped_ast_id(db, scope)
             }
         }
     };
@@ -132,20 +146,29 @@ impl_has_scoped_expression_id!(ast::ExprSlice);
 impl_has_scoped_expression_id!(ast::ExprIpyEscapeCommand);
 impl_has_scoped_expression_id!(ast::Expr);
 
-impl HasScopedExpressionId for ast::ExpressionRef<'_> {
-    fn scoped_expression_id(&self, db: &dyn Db, scope: ScopeId) -> ScopedExpressionId {
+impl HasScopedAstId for ast::ExpressionRef<'_> {
+    type Id = ScopedExpressionId;
+
+    fn scoped_ast_id(&self, db: &dyn Db, scope: ScopeId) -> Self::Id {
         let ast_ids = ast_ids(db, scope);
         ast_ids.expression_id(*self)
     }
 }
 
-#[derive(Debug, Default)]
+#[derive(Debug)]
 pub(super) struct AstIdsBuilder {
     expressions_map: FxHashMap<ExpressionNodeKey, ScopedExpressionId>,
     uses_map: FxHashMap<ExpressionNodeKey, ScopedUseId>,
 }
 
 impl AstIdsBuilder {
+    pub(super) fn new() -> Self {
+        Self {
+            expressions_map: FxHashMap::default(),
+            uses_map: FxHashMap::default(),
+        }
+    }
+
     /// Adds `expr` to the expression ids map and returns its id.
     pub(super) fn record_expression(&mut self, expr: &ast::Expr) -> ScopedExpressionId {
         let expression_id = self.expressions_map.len().into();

crates/red_knot_python_semantic/src/semantic_index/builder.rs

@@ -124,9 +124,9 @@ impl<'db> SemanticIndexBuilder<'db> {
         self.try_node_context_stack_manager.enter_nested_scope();
 
         let file_scope_id = self.scopes.push(scope);
-        self.symbol_tables.push(SymbolTableBuilder::default());
-        self.use_def_maps.push(UseDefMapBuilder::default());
-        let ast_id_scope = self.ast_ids.push(AstIdsBuilder::default());
+        self.symbol_tables.push(SymbolTableBuilder::new());
+        self.use_def_maps.push(UseDefMapBuilder::new());
+        let ast_id_scope = self.ast_ids.push(AstIdsBuilder::new());
 
         let scope_id = ScopeId::new(self.db, self.file, file_scope_id, countme::Count::default());
 
@@ -373,11 +373,6 @@ impl<'db> SemanticIndexBuilder<'db> {
                 if let Some(default) = default {
                     self.visit_expr(default);
                 }
-                match type_param {
-                    ast::TypeParam::TypeVar(node) => self.add_definition(symbol, node),
-                    ast::TypeParam::ParamSpec(node) => self.add_definition(symbol, node),
-                    ast::TypeParam::TypeVarTuple(node) => self.add_definition(symbol, node),
-                };
             }
         }
 
@@ -676,18 +671,9 @@ where
                 if let Some(value) = &node.value {
                     self.visit_expr(value);
                 }
-
-                // See https://docs.python.org/3/library/ast.html#ast.AnnAssign
-                if matches!(
-                    *node.target,
-                    ast::Expr::Attribute(_) | ast::Expr::Subscript(_) | ast::Expr::Name(_)
-                ) {
-                    self.push_assignment(node.into());
-                    self.visit_expr(&node.target);
-                    self.pop_assignment();
-                } else {
-                    self.visit_expr(&node.target);
-                }
+                self.push_assignment(node.into());
+                self.visit_expr(&node.target);
+                self.pop_assignment();
             }
             ast::Stmt::AugAssign(
                 aug_assign @ ast::StmtAugAssign {
@@ -699,18 +685,9 @@ where
             ) => {
                 debug_assert_eq!(&self.current_assignments, &[]);
                 self.visit_expr(value);
-
-                // See https://docs.python.org/3/library/ast.html#ast.AugAssign
-                if matches!(
-                    **target,
-                    ast::Expr::Attribute(_) | ast::Expr::Subscript(_) | ast::Expr::Name(_)
-                ) {
-                    self.push_assignment(aug_assign.into());
-                    self.visit_expr(target);
-                    self.pop_assignment();
-                } else {
-                    self.visit_expr(target);
-                }
+                self.push_assignment(aug_assign.into());
+                self.visit_expr(target);
+                self.pop_assignment();
             }
             ast::Stmt::If(node) => {
                 self.visit_expr(&node.test);
@@ -1090,15 +1067,9 @@ where
             ast::Expr::Named(node) => {
                 // TODO walrus in comprehensions is implicitly nonlocal
                 self.visit_expr(&node.value);
-
-                // See https://peps.python.org/pep-0572/#differences-between-assignment-expressions-and-assignment-statements
-                if node.target.is_name_expr() {
-                    self.push_assignment(node.into());
-                    self.visit_expr(&node.target);
-                    self.pop_assignment();
-                } else {
-                    self.visit_expr(&node.target);
-                }
+                self.push_assignment(node.into());
+                self.visit_expr(&node.target);
+                self.pop_assignment();
             }
             ast::Expr::Lambda(lambda) => {
                 if let Some(parameters) = &lambda.parameters {

crates/red_knot_python_semantic/src/semantic_index/definition.rs

@@ -92,9 +92,6 @@ pub(crate) enum DefinitionNodeRef<'a> {
     WithItem(WithItemDefinitionNodeRef<'a>),
     MatchPattern(MatchPatternDefinitionNodeRef<'a>),
     ExceptHandler(ExceptHandlerDefinitionNodeRef<'a>),
-    TypeVar(&'a ast::TypeParamTypeVar),
-    ParamSpec(&'a ast::TypeParamParamSpec),
-    TypeVarTuple(&'a ast::TypeParamTypeVarTuple),
 }
 
 impl<'a> From<&'a ast::StmtFunctionDef> for DefinitionNodeRef<'a> {
@@ -133,24 +130,6 @@ impl<'a> From<&'a ast::Alias> for DefinitionNodeRef<'a> {
     }
 }
 
-impl<'a> From<&'a ast::TypeParamTypeVar> for DefinitionNodeRef<'a> {
-    fn from(value: &'a ast::TypeParamTypeVar) -> Self {
-        Self::TypeVar(value)
-    }
-}
-
-impl<'a> From<&'a ast::TypeParamParamSpec> for DefinitionNodeRef<'a> {
-    fn from(value: &'a ast::TypeParamParamSpec) -> Self {
-        Self::ParamSpec(value)
-    }
-}
-
-impl<'a> From<&'a ast::TypeParamTypeVarTuple> for DefinitionNodeRef<'a> {
-    fn from(value: &'a ast::TypeParamTypeVarTuple) -> Self {
-        Self::TypeVarTuple(value)
-    }
-}
-
 impl<'a> From<ImportFromDefinitionNodeRef<'a>> for DefinitionNodeRef<'a> {
     fn from(node_ref: ImportFromDefinitionNodeRef<'a>) -> Self {
         Self::ImportFrom(node_ref)
@@ -338,15 +317,6 @@ impl<'db> DefinitionNodeRef<'db> {
                 handler: AstNodeRef::new(parsed, handler),
                 is_star,
             }),
-            DefinitionNodeRef::TypeVar(node) => {
-                DefinitionKind::TypeVar(AstNodeRef::new(parsed, node))
-            }
-            DefinitionNodeRef::ParamSpec(node) => {
-                DefinitionKind::ParamSpec(AstNodeRef::new(parsed, node))
-            }
-            DefinitionNodeRef::TypeVarTuple(node) => {
-                DefinitionKind::TypeVarTuple(AstNodeRef::new(parsed, node))
-            }
         }
     }
 
@@ -386,9 +356,6 @@ impl<'db> DefinitionNodeRef<'db> {
                 identifier.into()
             }
             Self::ExceptHandler(ExceptHandlerDefinitionNodeRef { handler, .. }) => handler.into(),
-            Self::TypeVar(node) => node.into(),
-            Self::ParamSpec(node) => node.into(),
-            Self::TypeVarTuple(node) => node.into(),
         }
     }
 }
@@ -445,9 +412,6 @@ pub enum DefinitionKind<'db> {
     WithItem(WithItemDefinitionKind),
     MatchPattern(MatchPatternDefinitionKind),
     ExceptHandler(ExceptHandlerDefinitionKind),
-    TypeVar(AstNodeRef<ast::TypeParamTypeVar>),
-    ParamSpec(AstNodeRef<ast::TypeParamParamSpec>),
-    TypeVarTuple(AstNodeRef<ast::TypeParamTypeVarTuple>),
 }
 
 impl DefinitionKind<'_> {
@@ -457,10 +421,7 @@ impl DefinitionKind<'_> {
             DefinitionKind::Function(_)
             | DefinitionKind::Class(_)
             | DefinitionKind::Import(_)
-            | DefinitionKind::ImportFrom(_)
-            | DefinitionKind::TypeVar(_)
-            | DefinitionKind::ParamSpec(_)
-            | DefinitionKind::TypeVarTuple(_) => DefinitionCategory::DeclarationAndBinding,
+            | DefinitionKind::ImportFrom(_) => DefinitionCategory::DeclarationAndBinding,
             // a parameter always binds a value, but is only a declaration if annotated
             DefinitionKind::Parameter(parameter) => {
                 if parameter.annotation.is_some() {
@@ -735,21 +696,3 @@ impl From<&ast::ExceptHandlerExceptHandler> for DefinitionNodeKey {
         Self(NodeKey::from_node(handler))
     }
 }
-
-impl From<&ast::TypeParamTypeVar> for DefinitionNodeKey {
-    fn from(value: &ast::TypeParamTypeVar) -> Self {
-        Self(NodeKey::from_node(value))
-    }
-}
-
-impl From<&ast::TypeParamParamSpec> for DefinitionNodeKey {
-    fn from(value: &ast::TypeParamParamSpec) -> Self {
-        Self(NodeKey::from_node(value))
-    }
-}
-
-impl From<&ast::TypeParamTypeVarTuple> for DefinitionNodeKey {
-    fn from(value: &ast::TypeParamTypeVarTuple) -> Self {
-        Self(NodeKey::from_node(value))
-    }
-}

crates/red_knot_python_semantic/src/semantic_index/symbol.rs

@@ -210,7 +210,7 @@ impl ScopeKind {
 }
 
 /// Symbol table for a specific [`Scope`].
-#[derive(Debug, Default)]
+#[derive(Debug)]
 pub struct SymbolTable {
     /// The symbols in this scope.
     symbols: IndexVec<ScopedSymbolId, Symbol>,
@@ -220,6 +220,13 @@ pub struct SymbolTable {
 }
 
 impl SymbolTable {
+    fn new() -> Self {
+        Self {
+            symbols: IndexVec::new(),
+            symbols_by_name: SymbolMap::default(),
+        }
+    }
+
     fn shrink_to_fit(&mut self) {
         self.symbols.shrink_to_fit();
     }
@@ -271,12 +278,18 @@ impl PartialEq for SymbolTable {
 
 impl Eq for SymbolTable {}
 
-#[derive(Debug, Default)]
+#[derive(Debug)]
 pub(super) struct SymbolTableBuilder {
     table: SymbolTable,
 }
 
 impl SymbolTableBuilder {
+    pub(super) fn new() -> Self {
+        Self {
+            table: SymbolTable::new(),
+        }
+    }
+
     pub(super) fn add_symbol(&mut self, name: Name) -> (ScopedSymbolId, bool) {
         let hash = SymbolTable::hash_name(&name);
         let entry = self

crates/red_knot_python_semantic/src/semantic_index/use_def.rs

@@ -277,7 +277,7 @@ impl<'db> UseDefMap<'db> {
 
     pub(crate) fn use_boundness(&self, use_id: ScopedUseId) -> Boundness {
         if self.bindings_by_use[use_id].may_be_unbound() {
-            Boundness::PossiblyUnbound
+            Boundness::MayBeUnbound
         } else {
             Boundness::Bound
         }
@@ -292,7 +292,7 @@ impl<'db> UseDefMap<'db> {
 
     pub(crate) fn public_boundness(&self, symbol: ScopedSymbolId) -> Boundness {
         if self.public_symbols[symbol].may_be_unbound() {
-            Boundness::PossiblyUnbound
+            Boundness::MayBeUnbound
         } else {
             Boundness::Bound
         }
@@ -459,6 +459,10 @@ pub(super) struct UseDefMapBuilder<'db> {
 }
 
 impl<'db> UseDefMapBuilder<'db> {
+    pub(super) fn new() -> Self {
+        Self::default()
+    }
+
     pub(super) fn add_symbol(&mut self, symbol: ScopedSymbolId) {
         let new_symbol = self.symbol_states.push(SymbolState::undefined());
         debug_assert_eq!(symbol, new_symbol);

crates/red_knot_python_semantic/src/semantic_model.rs

@@ -6,7 +6,7 @@ use ruff_source_file::LineIndex;
 
 use crate::module_name::ModuleName;
 use crate::module_resolver::{resolve_module, Module};
-use crate::semantic_index::ast_ids::HasScopedExpressionId;
+use crate::semantic_index::ast_ids::HasScopedAstId;
 use crate::semantic_index::semantic_index;
 use crate::types::{binding_ty, infer_scope_types, Type};
 use crate::Db;
@@ -54,7 +54,7 @@ impl HasTy for ast::ExpressionRef<'_> {
         let file_scope = index.expression_scope_id(*self);
         let scope = file_scope.to_scope_id(model.db, model.file);
 
-        let expression_id = self.scoped_expression_id(model.db, scope);
+        let expression_id = self.scoped_ast_id(model.db, scope);
         infer_scope_types(model.db, scope).expression_ty(expression_id)
     }
 }

crates/red_knot_python_semantic/src/site_packages.rs

@@ -732,20 +732,7 @@ mod tests {
         let system = TestSystem::default();
         assert!(matches!(
             VirtualEnvironment::new("/.venv", &system),
-            Err(SitePackagesDiscoveryError::VenvDirCanonicalizationError(..))
-        ));
-    }
-
-    #[test]
-    fn reject_venv_that_is_not_a_directory() {
-        let system = TestSystem::default();
-        system
-            .memory_file_system()
-            .write_file("/.venv", "")
-            .unwrap();
-        assert!(matches!(
-            VirtualEnvironment::new("/.venv", &system),
-            Err(SitePackagesDiscoveryError::VenvDirIsNotADirectory(..))
+            Err(SitePackagesDiscoveryError::VenvDirIsNotADirectory(_))
         ));
     }
 

crates/red_knot_python_semantic/src/stdlib.rs

@@ -8,38 +8,32 @@ use crate::Db;
 
 /// Enumeration of various core stdlib modules, for which we have dedicated Salsa queries.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub(crate) enum CoreStdlibModule {
+enum CoreStdlibModule {
     Builtins,
     Types,
     Typeshed,
     TypingExtensions,
     Typing,
-    Sys,
 }
 
 impl CoreStdlibModule {
-    pub(crate) const fn as_str(self) -> &'static str {
-        match self {
+    fn name(self) -> ModuleName {
+        let module_name = match self {
             Self::Builtins => "builtins",
             Self::Types => "types",
             Self::Typing => "typing",
             Self::Typeshed => "_typeshed",
             Self::TypingExtensions => "typing_extensions",
-            Self::Sys => "sys",
-        }
-    }
-
-    pub(crate) fn name(self) -> ModuleName {
-        let self_as_str = self.as_str();
-        ModuleName::new_static(self_as_str)
-            .unwrap_or_else(|| panic!("{self_as_str} should be a valid module name!"))
+        };
+        ModuleName::new_static(module_name)
+            .unwrap_or_else(|| panic!("{module_name} should be a valid module name!"))
     }
 }
 
 /// Lookup the type of `symbol` in a given core module
 ///
 /// Returns `Symbol::Unbound` if the given core module cannot be resolved for some reason
-pub(crate) fn core_module_symbol<'db>(
+fn core_module_symbol<'db>(
     db: &'db dyn Db,
     core_module: CoreStdlibModule,
     symbol: &str,
@@ -57,14 +51,29 @@ pub(crate) fn builtins_symbol<'db>(db: &'db dyn Db, symbol: &str) -> Symbol<'db>
     core_module_symbol(db, CoreStdlibModule::Builtins, symbol)
 }
 
+/// Lookup the type of `symbol` in the `types` module namespace.
+///
+/// Returns `Symbol::Unbound` if the `types` module isn't available for some reason.
+#[inline]
+pub(crate) fn types_symbol<'db>(db: &'db dyn Db, symbol: &str) -> Symbol<'db> {
+    core_module_symbol(db, CoreStdlibModule::Types, symbol)
+}
+
 /// Lookup the type of `symbol` in the `typing` module namespace.
 ///
 /// Returns `Symbol::Unbound` if the `typing` module isn't available for some reason.
 #[inline]
-#[cfg(test)]
+#[allow(dead_code)] // currently only used in tests
 pub(crate) fn typing_symbol<'db>(db: &'db dyn Db, symbol: &str) -> Symbol<'db> {
     core_module_symbol(db, CoreStdlibModule::Typing, symbol)
 }
+/// Lookup the type of `symbol` in the `_typeshed` module namespace.
+///
+/// Returns `Symbol::Unbound` if the `_typeshed` module isn't available for some reason.
+#[inline]
+pub(crate) fn typeshed_symbol<'db>(db: &'db dyn Db, symbol: &str) -> Symbol<'db> {
+    core_module_symbol(db, CoreStdlibModule::Typeshed, symbol)
+}
 
 /// Lookup the type of `symbol` in the `typing_extensions` module namespace.
 ///

crates/red_knot_python_semantic/src/symbol.rs

@@ -3,19 +3,10 @@ use crate::{
     Db,
 };
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq)]
 pub(crate) enum Boundness {
     Bound,
-    PossiblyUnbound,
-}
-
-impl Boundness {
-    pub(crate) fn or(self, other: Boundness) -> Boundness {
-        match (self, other) {
-            (Boundness::Bound, _) | (_, Boundness::Bound) => Boundness::Bound,
-            (Boundness::PossiblyUnbound, Boundness::PossiblyUnbound) => Boundness::PossiblyUnbound,
-        }
-    }
+    MayBeUnbound,
 }
 
 /// The result of a symbol lookup, which can either be a (possibly unbound) type
@@ -26,14 +17,14 @@ impl Boundness {
 /// bound = 1
 ///
 /// if flag:
-///     possibly_unbound = 2
+///     maybe_unbound = 2
 /// ```
 ///
 /// If we look up symbols in this scope, we would get the following results:
 /// ```rs
-/// bound:             Symbol::Type(Type::IntLiteral(1), Boundness::Bound),
-/// possibly_unbound:  Symbol::Type(Type::IntLiteral(2), Boundness::PossiblyUnbound),
-/// non_existent:      Symbol::Unbound,
+/// bound:          Symbol::Type(Type::IntLiteral(1), Boundness::Bound),
+/// maybe_unbound:  Symbol::Type(Type::IntLiteral(2), Boundness::MayBeUnbound),
+/// non_existent:   Symbol::Unbound,
 /// ```
 #[derive(Debug, Clone, PartialEq)]
 pub(crate) enum Symbol<'db> {
@@ -46,18 +37,25 @@ impl<'db> Symbol<'db> {
         matches!(self, Symbol::Unbound)
     }
 
-    pub(crate) fn possibly_unbound(&self) -> bool {
+    pub(crate) fn may_be_unbound(&self) -> bool {
         match self {
-            Symbol::Type(_, Boundness::PossiblyUnbound) | Symbol::Unbound => true,
+            Symbol::Type(_, Boundness::MayBeUnbound) | Symbol::Unbound => true,
             Symbol::Type(_, Boundness::Bound) => false,
         }
     }
 
-    /// Returns the type of the symbol, ignoring possible unboundness.
-    ///
-    /// If the symbol is *definitely* unbound, this function will return `None`. Otherwise,
-    /// if there is at least one control-flow path where the symbol is bound, return the type.
-    pub(crate) fn ignore_possibly_unbound(&self) -> Option<Type<'db>> {
+    pub(crate) fn unwrap_or(&self, other: Type<'db>) -> Type<'db> {
+        match self {
+            Symbol::Type(ty, _) => *ty,
+            Symbol::Unbound => other,
+        }
+    }
+
+    pub(crate) fn unwrap_or_unknown(&self) -> Type<'db> {
+        self.unwrap_or(Type::Unknown)
+    }
+
+    pub(crate) fn as_type(&self) -> Option<Type<'db>> {
         match self {
             Symbol::Type(ty, _) => Some(*ty),
             Symbol::Unbound => None,
@@ -67,80 +65,28 @@ impl<'db> Symbol<'db> {
     #[cfg(test)]
     #[track_caller]
     pub(crate) fn expect_type(self) -> Type<'db> {
-        self.ignore_possibly_unbound()
+        self.as_type()
             .expect("Expected a (possibly unbound) type, not an unbound symbol")
     }
 
     #[must_use]
-    pub(crate) fn or_fall_back_to(self, db: &'db dyn Db, fallback: &Symbol<'db>) -> Symbol<'db> {
-        match fallback {
-            Symbol::Type(fallback_ty, fallback_boundness) => match self {
-                Symbol::Type(_, Boundness::Bound) => self,
-                Symbol::Type(ty, boundness @ Boundness::PossiblyUnbound) => Symbol::Type(
-                    UnionType::from_elements(db, [*fallback_ty, ty]),
-                    fallback_boundness.or(boundness),
-                ),
-                Symbol::Unbound => fallback.clone(),
-            },
+    pub(crate) fn replace_unbound_with(
+        self,
+        db: &'db dyn Db,
+        replacement: &Symbol<'db>,
+    ) -> Symbol<'db> {
+        match replacement {
+            Symbol::Type(replacement, _) => Symbol::Type(
+                match self {
+                    Symbol::Type(ty, Boundness::Bound) => ty,
+                    Symbol::Type(ty, Boundness::MayBeUnbound) => {
+                        UnionType::from_elements(db, [*replacement, ty])
+                    }
+                    Symbol::Unbound => *replacement,
+                },
+                Boundness::Bound,
+            ),
             Symbol::Unbound => self,
         }
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::types::tests::setup_db;
-
-    #[test]
-    fn test_symbol_or_fall_back_to() {
-        use Boundness::{Bound, PossiblyUnbound};
-
-        let db = setup_db();
-        let ty1 = Type::IntLiteral(1);
-        let ty2 = Type::IntLiteral(2);
-
-        // Start from an unbound symbol
-        assert_eq!(
-            Symbol::Unbound.or_fall_back_to(&db, &Symbol::Unbound),
-            Symbol::Unbound
-        );
-        assert_eq!(
-            Symbol::Unbound.or_fall_back_to(&db, &Symbol::Type(ty1, PossiblyUnbound)),
-            Symbol::Type(ty1, PossiblyUnbound)
-        );
-        assert_eq!(
-            Symbol::Unbound.or_fall_back_to(&db, &Symbol::Type(ty1, Bound)),
-            Symbol::Type(ty1, Bound)
-        );
-
-        // Start from a possibly unbound symbol
-        assert_eq!(
-            Symbol::Type(ty1, PossiblyUnbound).or_fall_back_to(&db, &Symbol::Unbound),
-            Symbol::Type(ty1, PossiblyUnbound)
-        );
-        assert_eq!(
-            Symbol::Type(ty1, PossiblyUnbound)
-                .or_fall_back_to(&db, &Symbol::Type(ty2, PossiblyUnbound)),
-            Symbol::Type(UnionType::from_elements(&db, [ty2, ty1]), PossiblyUnbound)
-        );
-        assert_eq!(
-            Symbol::Type(ty1, PossiblyUnbound).or_fall_back_to(&db, &Symbol::Type(ty2, Bound)),
-            Symbol::Type(UnionType::from_elements(&db, [ty2, ty1]), Bound)
-        );
-
-        // Start from a definitely bound symbol
-        assert_eq!(
-            Symbol::Type(ty1, Bound).or_fall_back_to(&db, &Symbol::Unbound),
-            Symbol::Type(ty1, Bound)
-        );
-        assert_eq!(
-            Symbol::Type(ty1, Bound).or_fall_back_to(&db, &Symbol::Type(ty2, PossiblyUnbound)),
-            Symbol::Type(ty1, Bound)
-        );
-        assert_eq!(
-            Symbol::Type(ty1, Bound).or_fall_back_to(&db, &Symbol::Type(ty2, Bound)),
-            Symbol::Type(ty1, Bound)
-        );
-    }
-}

crates/red_knot_python_semantic/src/types/builder.rs

@@ -128,7 +128,7 @@ impl<'db> IntersectionBuilder<'db> {
     pub(crate) fn new(db: &'db dyn Db) -> Self {
         Self {
             db,
-            intersections: vec![InnerIntersectionBuilder::default()],
+            intersections: vec![InnerIntersectionBuilder::new()],
         }
     }
 
@@ -231,6 +231,10 @@ struct InnerIntersectionBuilder<'db> {
 }
 
 impl<'db> InnerIntersectionBuilder<'db> {
+    fn new() -> Self {
+        Self::default()
+    }
+
     /// Adds a positive type to this intersection.
     fn add_positive(&mut self, db: &'db dyn Db, new_positive: Type<'db>) {
         if let Type::Intersection(other) = new_positive {
@@ -242,14 +246,14 @@ impl<'db> InnerIntersectionBuilder<'db> {
             }
         } else {
             // ~Literal[True] & bool = Literal[False]
-            if let Type::Instance(InstanceType { class }) = new_positive {
+            if let Type::Instance(InstanceType { class, .. }) = new_positive {
                 if class.is_known(db, KnownClass::Bool) {
                     if let Some(&Type::BooleanLiteral(value)) = self
                         .negative
                         .iter()
                         .find(|element| element.is_boolean_literal())
                     {
-                        *self = Self::default();
+                        *self = Self::new();
                         self.positive.insert(Type::BooleanLiteral(!value));
                         return;
                     }
@@ -268,7 +272,7 @@ impl<'db> InnerIntersectionBuilder<'db> {
                 }
                 // A & B = Never    if A and B are disjoint
                 if new_positive.is_disjoint_from(db, *existing_positive) {
-                    *self = Self::default();
+                    *self = Self::new();
                     self.positive.insert(Type::Never);
                     return;
                 }
@@ -281,7 +285,7 @@ impl<'db> InnerIntersectionBuilder<'db> {
             for (index, existing_negative) in self.negative.iter().enumerate() {
                 // S & ~T = Never    if S <: T
                 if new_positive.is_subtype_of(db, *existing_negative) {
-                    *self = Self::default();
+                    *self = Self::new();
                     self.positive.insert(Type::Never);
                     return;
                 }
@@ -313,7 +317,7 @@ impl<'db> InnerIntersectionBuilder<'db> {
                 // Adding any of these types to the negative side of an intersection
                 // is equivalent to adding it to the positive side. We do this to
                 // simplify the representation.
-                self.add_positive(db, ty);
+                self.positive.insert(ty);
             }
             // ~Literal[True] & bool = Literal[False]
             Type::BooleanLiteral(bool)
@@ -322,7 +326,7 @@ impl<'db> InnerIntersectionBuilder<'db> {
                     .iter()
                     .any(|pos| *pos == KnownClass::Bool.to_instance(db)) =>
             {
-                *self = Self::default();
+                *self = Self::new();
                 self.positive.insert(Type::BooleanLiteral(!bool));
             }
             _ => {
@@ -344,7 +348,7 @@ impl<'db> InnerIntersectionBuilder<'db> {
                 for existing_positive in &self.positive {
                     // S & ~T = Never    if S <: T
                     if existing_positive.is_subtype_of(db, new_negative) {
-                        *self = Self::default();
+                        *self = Self::new();
                         self.positive.insert(Type::Never);
                         return;
                     }
@@ -379,7 +383,7 @@ mod tests {
     use crate::program::{Program, SearchPathSettings};
     use crate::python_version::PythonVersion;
     use crate::stdlib::typing_symbol;
-    use crate::types::{global_symbol, KnownClass, UnionBuilder};
+    use crate::types::{global_symbol, KnownClass, StringLiteralType, UnionBuilder};
     use crate::ProgramSettings;
     use ruff_db::files::system_path_to_file;
     use ruff_db::system::{DbWithTestSystem, SystemPathBuf};
@@ -588,22 +592,6 @@ mod tests {
         assert_eq!(ta_not_i0.display(&db).to_string(), "int & Any | Literal[1]");
     }
 
-    #[test]
-    fn build_intersection_simplify_negative_any() {
-        let db = setup_db();
-
-        let ty = IntersectionBuilder::new(&db)
-            .add_negative(Type::Any)
-            .build();
-        assert_eq!(ty, Type::Any);
-
-        let ty = IntersectionBuilder::new(&db)
-            .add_positive(Type::Never)
-            .add_negative(Type::Any)
-            .build();
-        assert_eq!(ty, Type::Never);
-    }
-
     #[test]
     fn intersection_distributes_over_union() {
         let db = setup_db();
@@ -771,7 +759,7 @@ mod tests {
             .build();
         assert_eq!(ty, s);
 
-        let literal = Type::string_literal(&db, "a");
+        let literal = Type::StringLiteral(StringLiteralType::new(&db, "a"));
         let expected = IntersectionBuilder::new(&db)
             .add_positive(s)
             .add_negative(literal)
@@ -874,7 +862,7 @@ mod tests {
 
         let ty = IntersectionBuilder::new(&db)
             .add_positive(s)
-            .add_negative(Type::string_literal(&db, "a"))
+            .add_negative(Type::StringLiteral(StringLiteralType::new(&db, "a")))
             .add_negative(t)
             .build();
         assert_eq!(ty, Type::Never);
@@ -908,7 +896,7 @@ mod tests {
         let db = setup_db();
 
         let t_p = KnownClass::Int.to_instance(&db);
-        let t_n = Type::string_literal(&db, "t_n");
+        let t_n = Type::StringLiteral(StringLiteralType::new(&db, "t_n"));
 
         let ty = IntersectionBuilder::new(&db)
             .add_positive(t_p)

crates/red_knot_python_semantic/src/types/diagnostic.rs

@@ -1,14 +1,13 @@
-use crate::types::{ClassLiteralType, Type};
-use crate::Db;
-use ruff_db::diagnostic::{Diagnostic, Severity};
 use ruff_db::files::File;
 use ruff_python_ast::{self as ast, AnyNodeRef};
 use ruff_text_size::{Ranged, TextRange};
-use std::borrow::Cow;
 use std::fmt::Formatter;
 use std::ops::Deref;
 use std::sync::Arc;
 
+use crate::types::{ClassLiteralType, Type};
+use crate::Db;
+
 #[derive(Debug, Eq, PartialEq, Clone)]
 pub struct TypeCheckDiagnostic {
     // TODO: Don't use string keys for rules
@@ -32,28 +31,6 @@ impl TypeCheckDiagnostic {
     }
 }
 
-impl Diagnostic for TypeCheckDiagnostic {
-    fn rule(&self) -> &str {
-        TypeCheckDiagnostic::rule(self)
-    }
-
-    fn message(&self) -> Cow<str> {
-        TypeCheckDiagnostic::message(self).into()
-    }
-
-    fn file(&self) -> File {
-        TypeCheckDiagnostic::file(self)
-    }
-
-    fn range(&self) -> Option<TextRange> {
-        Some(Ranged::range(self))
-    }
-
-    fn severity(&self) -> Severity {
-        Severity::Error
-    }
-}
-
 impl Ranged for TypeCheckDiagnostic {
     fn range(&self) -> TextRange {
         self.range
@@ -73,6 +50,10 @@ pub struct TypeCheckDiagnostics {
 }
 
 impl TypeCheckDiagnostics {
+    pub fn new() -> Self {
+        Self { inner: Vec::new() }
+    }
+
     pub(super) fn push(&mut self, diagnostic: TypeCheckDiagnostic) {
         self.inner.push(Arc::new(diagnostic));
     }
@@ -144,7 +125,7 @@ impl<'db> TypeCheckDiagnosticsBuilder<'db> {
         Self {
             db,
             file,
-            diagnostics: TypeCheckDiagnostics::default(),
+            diagnostics: TypeCheckDiagnostics::new(),
         }
     }
 
@@ -160,23 +141,6 @@ impl<'db> TypeCheckDiagnosticsBuilder<'db> {
         );
     }
 
-    /// Emit a diagnostic declaring that the object represented by `node` is not iterable
-    /// because its `__iter__` method is possibly unbound.
-    pub(super) fn add_not_iterable_possibly_unbound(
-        &mut self,
-        node: AnyNodeRef,
-        element_ty: Type<'db>,
-    ) {
-        self.add(
-            node,
-            "not-iterable",
-            format_args!(
-                "Object of type `{}` is not iterable because its `__iter__` method is possibly unbound",
-                element_ty.display(self.db)
-            ),
-        );
-    }
-
     /// Emit a diagnostic declaring that an index is out of bounds for a tuple.
     pub(super) fn add_index_out_of_bounds(
         &mut self,

crates/red_knot_python_semantic/src/types/display.rs

@@ -1,15 +1,12 @@
 //! Display implementations for types.
 
-use std::fmt::{self, Display, Formatter, Write};
+use std::fmt::{self, Display, Formatter};
 
 use ruff_db::display::FormatterJoinExtension;
 use ruff_python_ast::str::Quote;
 use ruff_python_literal::escape::AsciiEscape;
 
-use crate::types::{
-    ClassLiteralType, InstanceType, IntersectionType, KnownClass, StringLiteralType,
-    SubclassOfType, Type, UnionType,
-};
+use crate::types::{ClassLiteralType, InstanceType, IntersectionType, KnownClass, Type, UnionType};
 use crate::Db;
 use rustc_hash::FxHashMap;
 
@@ -67,13 +64,10 @@ impl Display for DisplayRepresentation<'_> {
             Type::Any => f.write_str("Any"),
             Type::Never => f.write_str("Never"),
             Type::Unknown => f.write_str("Unknown"),
-            Type::Instance(InstanceType { class }) => {
-                let representation = match class.known(self.db) {
-                    Some(KnownClass::NoneType) => "None",
-                    Some(KnownClass::NoDefaultType) => "NoDefault",
-                    _ => class.name(self.db),
-                };
-                f.write_str(representation)
+            Type::Instance(InstanceType { class, .. })
+                if class.is_known(self.db, KnownClass::NoneType) =>
+            {
+                f.write_str("None")
             }
             // `[Type::Todo]`'s display should be explicit that is not a valid display of
             // any other type
@@ -83,16 +77,18 @@ impl Display for DisplayRepresentation<'_> {
             }
             // TODO functions and classes should display using a fully qualified name
             Type::ClassLiteral(ClassLiteralType { class }) => f.write_str(class.name(self.db)),
-            Type::SubclassOf(SubclassOfType { class }) => {
-                write!(f, "type[{}]", class.name(self.db))
-            }
-            Type::KnownInstance(known_instance) => f.write_str(known_instance.repr(self.db)),
+            Type::Instance(InstanceType { class, known }) => f.write_str(match known {
+                Some(super::KnownInstance::Literal) => "Literal",
+                _ => class.name(self.db),
+            }),
             Type::FunctionLiteral(function) => f.write_str(function.name(self.db)),
             Type::Union(union) => union.display(self.db).fmt(f),
             Type::Intersection(intersection) => intersection.display(self.db).fmt(f),
             Type::IntLiteral(n) => n.fmt(f),
             Type::BooleanLiteral(boolean) => f.write_str(if boolean { "True" } else { "False" }),
-            Type::StringLiteral(string) => string.display(self.db).fmt(f),
+            Type::StringLiteral(string) => {
+                write!(f, r#""{}""#, string.value(self.db).replace('"', r#"\""#))
+            }
             Type::LiteralString => f.write_str("LiteralString"),
             Type::BytesLiteral(bytes) => {
                 let escape =
@@ -327,40 +323,15 @@ impl<'db> Display for DisplayTypeArray<'_, 'db> {
     }
 }
 
-impl<'db> StringLiteralType<'db> {
-    fn display(&'db self, db: &'db dyn Db) -> DisplayStringLiteralType<'db> {
-        DisplayStringLiteralType { db, ty: self }
-    }
-}
-
-struct DisplayStringLiteralType<'db> {
-    ty: &'db StringLiteralType<'db>,
-    db: &'db dyn Db,
-}
-
-impl Display for DisplayStringLiteralType<'_> {
-    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
-        let value = self.ty.value(self.db);
-        f.write_char('"')?;
-        for ch in value.chars() {
-            match ch {
-                // `escape_debug` will escape even single quotes, which is not necessary for our
-                // use case as we are already using double quotes to wrap the string.
-                '\'' => f.write_char('\'')?,
-                _ => write!(f, "{}", ch.escape_debug())?,
-            }
-        }
-        f.write_char('"')
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use ruff_db::files::system_path_to_file;
     use ruff_db::system::{DbWithTestSystem, SystemPathBuf};
 
     use crate::db::tests::TestDb;
-    use crate::types::{global_symbol, SliceLiteralType, StringLiteralType, Type, UnionType};
+    use crate::types::{
+        global_symbol, BytesLiteralType, SliceLiteralType, StringLiteralType, Type, UnionType,
+    };
     use crate::{Program, ProgramSettings, PythonVersion, SearchPathSettings};
 
     fn setup_db() -> TestDb {
@@ -406,12 +377,12 @@ mod tests {
             Type::Unknown,
             Type::IntLiteral(-1),
             global_symbol(&db, mod_file, "A").expect_type(),
-            Type::string_literal(&db, "A"),
-            Type::bytes_literal(&db, &[0u8]),
-            Type::bytes_literal(&db, &[7u8]),
+            Type::StringLiteral(StringLiteralType::new(&db, "A")),
+            Type::BytesLiteral(BytesLiteralType::new(&db, [0u8].as_slice())),
+            Type::BytesLiteral(BytesLiteralType::new(&db, [7u8].as_slice())),
             Type::IntLiteral(0),
             Type::IntLiteral(1),
-            Type::string_literal(&db, "B"),
+            Type::StringLiteral(StringLiteralType::new(&db, "B")),
             global_symbol(&db, mod_file, "foo").expect_type(),
             global_symbol(&db, mod_file, "bar").expect_type(),
             global_symbol(&db, mod_file, "B").expect_type(),
@@ -477,28 +448,4 @@ mod tests {
             "slice[None, None, Literal[2]]"
         );
     }
-
-    #[test]
-    fn string_literal_display() {
-        let db = setup_db();
-
-        assert_eq!(
-            Type::StringLiteral(StringLiteralType::new(&db, r"\n"))
-                .display(&db)
-                .to_string(),
-            r#"Literal["\\n"]"#
-        );
-        assert_eq!(
-            Type::StringLiteral(StringLiteralType::new(&db, "'"))
-                .display(&db)
-                .to_string(),
-            r#"Literal["'"]"#
-        );
-        assert_eq!(
-            Type::StringLiteral(StringLiteralType::new(&db, r#"""#))
-                .display(&db)
-                .to_string(),
-            r#"Literal["\""]"#
-        );
-    }
 }

crates/red_knot_python_semantic/src/types/mro.rs

@@ -1,10 +1,11 @@
 use std::collections::VecDeque;
 use std::ops::Deref;
 
+use indexmap::IndexSet;
 use itertools::Either;
 use rustc_hash::FxHashSet;
 
-use super::{Class, ClassLiteralType, KnownClass, KnownInstanceType, Type};
+use super::{Class, ClassLiteralType, KnownClass, Type};
 use crate::Db;
 
 /// The inferred method resolution order of a given class.
@@ -25,30 +26,22 @@ impl<'db> Mro<'db> {
     /// (We emit a diagnostic warning about the runtime `TypeError` in
     /// [`super::infer::TypeInferenceBuilder::infer_region_scope`].)
     pub(super) fn of_class(db: &'db dyn Db, class: Class<'db>) -> Result<Self, MroError<'db>> {
-        Self::of_class_impl(db, class).map_err(|error_kind| MroError {
-            kind: error_kind,
-            fallback_mro: Self::from_error(db, class),
+        Self::of_class_impl(db, class).map_err(|error_kind| {
+            let fallback_mro = Self::from([
+                ClassBase::Class(class),
+                ClassBase::Unknown,
+                ClassBase::object(db),
+            ]);
+            MroError {
+                kind: error_kind,
+                fallback_mro,
+            }
         })
     }
 
-    pub(super) fn from_error(db: &'db dyn Db, class: Class<'db>) -> Self {
-        Self::from([
-            ClassBase::Class(class),
-            ClassBase::Unknown,
-            ClassBase::object(db),
-        ])
-    }
-
     fn of_class_impl(db: &'db dyn Db, class: Class<'db>) -> Result<Self, MroErrorKind<'db>> {
         let class_bases = class.explicit_bases(db);
 
-        if !class_bases.is_empty() && class.is_cyclically_defined(db) {
-            // We emit errors for cyclically defined classes elsewhere.
-            // It's important that we don't even try to infer the MRO for a cyclically defined class,
-            // or we'll end up in an infinite loop.
-            return Ok(Mro::from_error(db, class));
-        }
-
         match class_bases {
             // `builtins.object` is the special case:
             // the only class in Python that has an MRO with length <2
@@ -84,6 +77,11 @@ impl<'db> Mro<'db> {
                         Err(MroErrorKind::InvalidBases(bases_info))
                     },
                     |single_base| {
+                        if let ClassBase::Class(class_base) = single_base {
+                            if class_is_cyclically_defined(db, class_base) {
+                                return Err(MroErrorKind::CyclicClassDefinition);
+                            }
+                        }
                         let mro = std::iter::once(ClassBase::Class(class))
                             .chain(single_base.mro(db))
                             .collect();
@@ -98,6 +96,10 @@ impl<'db> Mro<'db> {
             // what MRO Python will give this class at runtime
             // (if an MRO is indeed resolvable at all!)
             multiple_bases => {
+                if class_is_cyclically_defined(db, class) {
+                    return Err(MroErrorKind::CyclicClassDefinition);
+                }
+
                 let mut valid_bases = vec![];
                 let mut invalid_bases = vec![];
 
@@ -280,6 +282,13 @@ pub(super) enum MroErrorKind<'db> {
     /// Each index is the index of a node representing an invalid base.
     InvalidBases(Box<[(usize, Type<'db>)]>),
 
+    /// The class inherits from itself!
+    ///
+    /// This is very unlikely to happen in working real-world code,
+    /// but it's important to explicitly account for it.
+    /// If we don't, there's a possibility of an infinite loop and a panic.
+    CyclicClassDefinition,
+
     /// The class has one or more duplicate bases.
     ///
     /// This variant records the indices and [`Class`]es
@@ -340,7 +349,7 @@ impl<'db> ClassBase<'db> {
     /// Return a `ClassBase` representing the class `builtins.object`
     fn object(db: &'db dyn Db) -> Self {
         KnownClass::Object
-            .to_class_literal(db)
+            .to_class(db)
             .into_class_literal()
             .map_or(Self::Unknown, |ClassLiteralType { class }| {
                 Self::Class(class)
@@ -368,13 +377,7 @@ impl<'db> ClassBase<'db> {
             | Type::LiteralString
             | Type::Tuple(_)
             | Type::SliceLiteral(_)
-            | Type::ModuleLiteral(_)
-            | Type::SubclassOf(_) => None,
-            Type::KnownInstance(known_instance) => match known_instance {
-                KnownInstanceType::TypeVar(_)
-                | KnownInstanceType::Literal
-                | KnownInstanceType::Optional => None,
-            },
+            | Type::ModuleLiteral(_) => None,
         }
     }
 
@@ -407,7 +410,7 @@ impl<'db> From<ClassBase<'db>> for Type<'db> {
             ClassBase::Any => Type::Any,
             ClassBase::Todo => Type::Todo,
             ClassBase::Unknown => Type::Unknown,
-            ClassBase::Class(class) => Type::class_literal(class),
+            ClassBase::Class(class) => Type::ClassLiteral(ClassLiteralType { class }),
         }
     }
 }
@@ -453,3 +456,46 @@ fn c3_merge(mut sequences: Vec<VecDeque<ClassBase>>) -> Option<Mro> {
         }
     }
 }
+
+/// Return `true` if this class appears to be a cyclic definition,
+/// i.e., it inherits either directly or indirectly from itself.
+///
+/// A class definition like this will fail at runtime,
+/// but we must be resilient to it or we could panic.
+fn class_is_cyclically_defined(db: &dyn Db, class: Class) -> bool {
+    fn is_cyclically_defined_recursive<'db>(
+        db: &'db dyn Db,
+        class: Class<'db>,
+        classes_to_watch: &mut IndexSet<Class<'db>>,
+    ) -> bool {
+        if !classes_to_watch.insert(class) {
+            return true;
+        }
+        for explicit_base_class in class
+            .explicit_bases(db)
+            .iter()
+            .copied()
+            .filter_map(Type::into_class_literal)
+            .map(|ClassLiteralType { class }| class)
+        {
+            // Each base must be considered in isolation.
+            // This is due to the fact that if a class uses multiple inheritance,
+            // there could easily be a situation where two bases have the same class in their MROs;
+            // that isn't enough to constitute the class being cyclically defined.
+            let classes_to_watch_len = classes_to_watch.len();
+            if is_cyclically_defined_recursive(db, explicit_base_class, classes_to_watch) {
+                return true;
+            }
+            classes_to_watch.truncate(classes_to_watch_len);
+        }
+        false
+    }
+
+    class
+        .explicit_bases(db)
+        .iter()
+        .copied()
+        .filter_map(Type::into_class_literal)
+        .map(|ClassLiteralType { class }| class)
+        .any(|base_class| is_cyclically_defined_recursive(db, base_class, &mut IndexSet::default()))
+}

crates/red_knot_python_semantic/src/types/narrow.rs

@@ -1,12 +1,12 @@
-use crate::semantic_index::ast_ids::HasScopedExpressionId;
+use crate::semantic_index::ast_ids::HasScopedAstId;
 use crate::semantic_index::constraint::{Constraint, ConstraintNode, PatternConstraint};
 use crate::semantic_index::definition::Definition;
 use crate::semantic_index::expression::Expression;
 use crate::semantic_index::symbol::{ScopeId, ScopedSymbolId, SymbolTable};
 use crate::semantic_index::symbol_table;
 use crate::types::{
-    infer_expression_types, ClassLiteralType, IntersectionBuilder, KnownClass,
-    KnownConstraintFunction, KnownFunction, Truthiness, Type, UnionBuilder,
+    infer_expression_types, ClassLiteralType, IntersectionBuilder, KnownClass, KnownFunction,
+    Truthiness, Type, UnionBuilder,
 };
 use crate::Db;
 use itertools::Itertools;
@@ -78,27 +78,24 @@ fn all_negative_narrowing_constraints_for_expression<'db>(
     NarrowingConstraintsBuilder::new(db, ConstraintNode::Expression(expression), false).finish()
 }
 
-/// Generate a constraint from the type of a `classinfo` argument to `isinstance` or `issubclass`.
+/// Generate a constraint from the *type* of the second argument of an `isinstance` call.
 ///
-/// The `classinfo` argument can be a class literal, a tuple of (tuples of) class literals. PEP 604
-/// union types are not yet supported. Returns `None` if the `classinfo` argument has a wrong type.
-fn generate_classinfo_constraint<'db, F>(
+/// Example: for `isinstance(…, str)`, we would infer `Type::ClassLiteral(str)` from the
+/// second argument, but we need to generate a `Type::Instance(str)` constraint that can
+/// be used to narrow down the type of the first argument.
+fn generate_isinstance_constraint<'db>(
     db: &'db dyn Db,
     classinfo: &Type<'db>,
-    to_constraint: F,
-) -> Option<Type<'db>>
-where
-    F: Fn(ClassLiteralType<'db>) -> Type<'db> + Copy,
-{
+) -> Option<Type<'db>> {
     match classinfo {
+        Type::ClassLiteral(ClassLiteralType { class }) => Some(Type::anonymous_instance(*class)),
         Type::Tuple(tuple) => {
             let mut builder = UnionBuilder::new(db);
             for element in tuple.elements(db) {
-                builder = builder.add(generate_classinfo_constraint(db, element, to_constraint)?);
+                builder = builder.add(generate_isinstance_constraint(db, element)?);
             }
             Some(builder.build())
         }
-        Type::ClassLiteral(class_literal_type) => Some(to_constraint(*class_literal_type)),
         _ => None,
     }
 }
@@ -257,26 +254,17 @@ impl<'db> NarrowingConstraintsBuilder<'db> {
         expression: Expression<'db>,
         is_positive: bool,
     ) -> Option<NarrowingConstraints<'db>> {
-        fn is_narrowing_target_candidate(expr: &ast::Expr) -> bool {
-            matches!(expr, ast::Expr::Name(_) | ast::Expr::Call(_))
-        }
-
         let ast::ExprCompare {
             range: _,
             left,
             ops,
             comparators,
         } = expr_compare;
-
-        // Performance optimization: early return if there are no potential narrowing targets.
-        if !is_narrowing_target_candidate(left)
-            && comparators
-                .iter()
-                .all(|c| !is_narrowing_target_candidate(c))
-        {
+        if !left.is_name_expr() && comparators.iter().all(|c| !c.is_name_expr()) {
+            // If none of the comparators are name expressions,
+            // we have no symbol to narrow down the type of.
             return None;
         }
-
         if !is_positive && comparators.len() > 1 {
             // We can't negate a constraint made by a multi-comparator expression, since we can't
             // know which comparison part is the one being negated.
@@ -292,85 +280,42 @@ impl<'db> NarrowingConstraintsBuilder<'db> {
             .tuple_windows::<(&ruff_python_ast::Expr, &ruff_python_ast::Expr)>();
         let mut constraints = NarrowingConstraints::default();
         for (op, (left, right)) in std::iter::zip(&**ops, comparator_tuples) {
-            let rhs_ty = inference.expression_ty(right.scoped_expression_id(self.db, scope));
+            if let ast::Expr::Name(ast::ExprName {
+                range: _,
+                id,
+                ctx: _,
+            }) = left
+            {
+                // SAFETY: we should always have a symbol for every Name node.
+                let symbol = self.symbols().symbol_id_by_name(id).unwrap();
+                let rhs_ty = inference.expression_ty(right.scoped_ast_id(self.db, scope));
 
-            match left {
-                ast::Expr::Name(ast::ExprName {
-                    range: _,
-                    id,
-                    ctx: _,
-                }) => {
-                    let symbol = self
-                        .symbols()
-                        .symbol_id_by_name(id)
-                        .expect("Should always have a symbol for every Name node");
-
-                    match if is_positive { *op } else { op.negate() } {
-                        ast::CmpOp::IsNot => {
-                            if rhs_ty.is_singleton(self.db) {
-                                let ty = IntersectionBuilder::new(self.db)
-                                    .add_negative(rhs_ty)
-                                    .build();
-                                constraints.insert(symbol, ty);
-                            } else {
-                                // Non-singletons cannot be safely narrowed using `is not`
-                            }
+                match if is_positive { *op } else { op.negate() } {
+                    ast::CmpOp::IsNot => {
+                        if rhs_ty.is_singleton(self.db) {
+                            let ty = IntersectionBuilder::new(self.db)
+                                .add_negative(rhs_ty)
+                                .build();
+                            constraints.insert(symbol, ty);
+                        } else {
+                            // Non-singletons cannot be safely narrowed using `is not`
                         }
-                        ast::CmpOp::Is => {
-                            constraints.insert(symbol, rhs_ty);
-                        }
-                        ast::CmpOp::NotEq => {
-                            if rhs_ty.is_single_valued(self.db) {
-                                let ty = IntersectionBuilder::new(self.db)
-                                    .add_negative(rhs_ty)
-                                    .build();
-                                constraints.insert(symbol, ty);
-                            }
-                        }
-                        _ => {
-                            // TODO other comparison types
+                    }
+                    ast::CmpOp::Is => {
+                        constraints.insert(symbol, rhs_ty);
+                    }
+                    ast::CmpOp::NotEq => {
+                        if rhs_ty.is_single_valued(self.db) {
+                            let ty = IntersectionBuilder::new(self.db)
+                                .add_negative(rhs_ty)
+                                .build();
+                            constraints.insert(symbol, ty);
                         }
                     }
+                    _ => {
+                        // TODO other comparison types
+                    }
                 }
-                ast::Expr::Call(ast::ExprCall {
-                    range: _,
-                    func: callable,
-                    arguments:
-                        ast::Arguments {
-                            args,
-                            keywords,
-                            range: _,
-                        },
-                }) if rhs_ty.is_class_literal() && keywords.is_empty() => {
-                    let [ast::Expr::Name(ast::ExprName { id, .. })] = &**args else {
-                        continue;
-                    };
-
-                    let is_valid_constraint = if is_positive {
-                        op == &ast::CmpOp::Is
-                    } else {
-                        op == &ast::CmpOp::IsNot
-                    };
-
-                    if !is_valid_constraint {
-                        continue;
-                    }
-
-                    let callable_ty =
-                        inference.expression_ty(callable.scoped_expression_id(self.db, scope));
-
-                    if callable_ty
-                        .into_class_literal()
-                        .is_some_and(|c| c.class.is_known(self.db, KnownClass::Type))
-                    {
-                        let symbol = self
-                            .symbols()
-                            .symbol_id_by_name(id)
-                            .expect("Should always have a symbol for every Name node");
-                        constraints.insert(symbol, rhs_ty.to_instance(self.db));
-                    }
-                }
-                _ => {}
             }
         }
         Some(constraints)
@@ -385,49 +330,34 @@ impl<'db> NarrowingConstraintsBuilder<'db> {
         let scope = self.scope();
         let inference = infer_expression_types(self.db, expression);
 
-        // TODO: add support for PEP 604 union types on the right hand side of `isinstance`
-        // and `issubclass`, for example `isinstance(x, str | (int | float))`.
-        match inference
-            .expression_ty(expr_call.func.scoped_expression_id(self.db, scope))
+        if let Some(func_type) = inference
+            .expression_ty(expr_call.func.scoped_ast_id(self.db, scope))
             .into_function_literal()
-            .and_then(|f| f.known(self.db))
-            .and_then(KnownFunction::constraint_function)
         {
-            Some(function) if expr_call.arguments.keywords.is_empty() => {
-                if let [ast::Expr::Name(ast::ExprName { id, .. }), class_info] =
-                    &*expr_call.arguments.args
+            if func_type.is_known(self.db, KnownFunction::IsInstance)
+                && expr_call.arguments.keywords.is_empty()
+            {
+                if let [ast::Expr::Name(ast::ExprName { id, .. }), rhs] = &*expr_call.arguments.args
                 {
                     let symbol = self.symbols().symbol_id_by_name(id).unwrap();
 
-                    let class_info_ty =
-                        inference.expression_ty(class_info.scoped_expression_id(self.db, scope));
+                    let rhs_type = inference.expression_ty(rhs.scoped_ast_id(self.db, scope));
 
-                    let to_constraint = match function {
-                        KnownConstraintFunction::IsInstance => {
-                            |class_literal: ClassLiteralType<'db>| {
-                                Type::instance(class_literal.class)
-                            }
+                    // TODO: add support for PEP 604 union types on the right hand side:
+                    // isinstance(x, str | (int | float))
+                    if let Some(mut constraint) = generate_isinstance_constraint(self.db, &rhs_type)
+                    {
+                        if !is_positive {
+                            constraint = constraint.negate(self.db);
                         }
-                        KnownConstraintFunction::IsSubclass => {
-                            |class_literal: ClassLiteralType<'db>| {
-                                Type::subclass_of(class_literal.class)
-                            }
-                        }
-                    };
-
-                    generate_classinfo_constraint(self.db, &class_info_ty, to_constraint).map(
-                        |constraint| {
-                            let mut constraints = NarrowingConstraints::default();
-                            constraints.insert(symbol, constraint.negate_if(self.db, !is_positive));
-                            constraints
-                        },
-                    )
-                } else {
-                    None
+                        let mut constraints = NarrowingConstraints::default();
+                        constraints.insert(symbol, constraint);
+                        return Some(constraints);
+                    }
                 }
             }
-            _ => None,
         }
+        None
     }
 
     fn evaluate_match_pattern_singleton(
@@ -466,7 +396,7 @@ impl<'db> NarrowingConstraintsBuilder<'db> {
             // filter our arms with statically known truthiness
             .filter(|expr| {
                 inference
-                    .expression_ty(expr.scoped_expression_id(self.db, scope))
+                    .expression_ty(expr.scoped_ast_id(self.db, scope))
                     .bool(self.db)
                     != match expr_bool_op.op {
                         BoolOp::And => Truthiness::AlwaysTrue,

crates/red_knot_python_semantic/src/types/signatures.rs

@@ -1,480 +0,0 @@
-#![allow(dead_code)]
-use super::{definition_expression_ty, Type};
-use crate::semantic_index::definition::Definition;
-use crate::Db;
-use ruff_python_ast::{self as ast, name::Name};
-
-/// A typed callable signature.
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub(crate) struct Signature<'db> {
-    parameters: Parameters<'db>,
-
-    /// Annotated return type (Unknown if no annotation.)
-    pub(crate) return_ty: Type<'db>,
-}
-
-impl<'db> Signature<'db> {
-    /// Return a todo signature: (*args: Todo, **kwargs: Todo) -> Todo
-    pub(crate) fn todo() -> Self {
-        Self {
-            parameters: Parameters::todo(),
-            return_ty: Type::Todo,
-        }
-    }
-
-    /// Return a typed signature from a function definition.
-    pub(super) fn from_function(
-        db: &'db dyn Db,
-        definition: Definition<'db>,
-        function_node: &'db ast::StmtFunctionDef,
-    ) -> Self {
-        let return_ty = function_node
-            .returns
-            .as_ref()
-            .map(|returns| {
-                if function_node.is_async {
-                    // TODO: generic `types.CoroutineType`!
-                    Type::Todo
-                } else {
-                    definition_expression_ty(db, definition, returns.as_ref())
-                }
-            })
-            .unwrap_or(Type::Unknown);
-
-        Self {
-            parameters: Parameters::from_parameters(
-                db,
-                definition,
-                function_node.parameters.as_ref(),
-            ),
-            return_ty,
-        }
-    }
-}
-
-/// The parameters portion of a typed signature.
-///
-/// The ordering of parameters is always as given in this struct: first positional-only parameters,
-/// then positional-or-keyword, then optionally the variadic parameter, then keyword-only
-/// parameters, and last, optionally the variadic keywords parameter.
-#[derive(Clone, Debug, Default, PartialEq, Eq)]
-pub(super) struct Parameters<'db> {
-    /// Parameters which may only be filled by positional arguments.
-    positional_only: Box<[ParameterWithDefault<'db>]>,
-
-    /// Parameters which may be filled by positional or keyword arguments.
-    positional_or_keyword: Box<[ParameterWithDefault<'db>]>,
-
-    /// The `*args` variadic parameter, if any.
-    variadic: Option<Parameter<'db>>,
-
-    /// Parameters which may only be filled by keyword arguments.
-    keyword_only: Box<[ParameterWithDefault<'db>]>,
-
-    /// The `**kwargs` variadic keywords parameter, if any.
-    keywords: Option<Parameter<'db>>,
-}
-
-impl<'db> Parameters<'db> {
-    /// Return todo parameters: (*args: Todo, **kwargs: Todo)
-    fn todo() -> Self {
-        Self {
-            variadic: Some(Parameter {
-                name: Some(Name::new_static("args")),
-                annotated_ty: Type::Todo,
-            }),
-            keywords: Some(Parameter {
-                name: Some(Name::new_static("kwargs")),
-                annotated_ty: Type::Todo,
-            }),
-            ..Default::default()
-        }
-    }
-
-    fn from_parameters(
-        db: &'db dyn Db,
-        definition: Definition<'db>,
-        parameters: &'db ast::Parameters,
-    ) -> Self {
-        let ast::Parameters {
-            posonlyargs,
-            args,
-            vararg,
-            kwonlyargs,
-            kwarg,
-            range: _,
-        } = parameters;
-        let positional_only = posonlyargs
-            .iter()
-            .map(|arg| ParameterWithDefault::from_node(db, definition, arg))
-            .collect();
-        let positional_or_keyword = args
-            .iter()
-            .map(|arg| ParameterWithDefault::from_node(db, definition, arg))
-            .collect();
-        let variadic = vararg
-            .as_ref()
-            .map(|arg| Parameter::from_node(db, definition, arg));
-        let keyword_only = kwonlyargs
-            .iter()
-            .map(|arg| ParameterWithDefault::from_node(db, definition, arg))
-            .collect();
-        let keywords = kwarg
-            .as_ref()
-            .map(|arg| Parameter::from_node(db, definition, arg));
-        Self {
-            positional_only,
-            positional_or_keyword,
-            variadic,
-            keyword_only,
-            keywords,
-        }
-    }
-}
-
-/// A single parameter of a typed signature, with optional default value.
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub(super) struct ParameterWithDefault<'db> {
-    parameter: Parameter<'db>,
-
-    /// Type of the default value, if any.
-    default_ty: Option<Type<'db>>,
-}
-
-impl<'db> ParameterWithDefault<'db> {
-    fn from_node(
-        db: &'db dyn Db,
-        definition: Definition<'db>,
-        parameter_with_default: &'db ast::ParameterWithDefault,
-    ) -> Self {
-        Self {
-            default_ty: parameter_with_default
-                .default
-                .as_deref()
-                .map(|default| definition_expression_ty(db, definition, default)),
-            parameter: Parameter::from_node(db, definition, &parameter_with_default.parameter),
-        }
-    }
-}
-
-/// A single parameter of a typed signature.
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub(super) struct Parameter<'db> {
-    /// Parameter name.
-    ///
-    /// It is possible for signatures to be defined in ways that leave positional-only parameters
-    /// nameless (e.g. via `Callable` annotations).
-    name: Option<Name>,
-
-    /// Annotated type of the parameter (Unknown if no annotation.)
-    annotated_ty: Type<'db>,
-}
-
-impl<'db> Parameter<'db> {
-    fn from_node(
-        db: &'db dyn Db,
-        definition: Definition<'db>,
-        parameter: &'db ast::Parameter,
-    ) -> Self {
-        Parameter {
-            name: Some(parameter.name.id.clone()),
-            annotated_ty: parameter
-                .annotation
-                .as_deref()
-                .map(|annotation| definition_expression_ty(db, definition, annotation))
-                .unwrap_or(Type::Unknown),
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::db::tests::TestDb;
-    use crate::program::{Program, SearchPathSettings};
-    use crate::python_version::PythonVersion;
-    use crate::types::{global_symbol, FunctionType};
-    use crate::ProgramSettings;
-    use ruff_db::system::{DbWithTestSystem, SystemPathBuf};
-
-    pub(crate) fn setup_db() -> TestDb {
-        let db = TestDb::new();
-
-        let src_root = SystemPathBuf::from("/src");
-        db.memory_file_system()
-            .create_directory_all(&src_root)
-            .unwrap();
-
-        Program::from_settings(
-            &db,
-            &ProgramSettings {
-                target_version: PythonVersion::default(),
-                search_paths: SearchPathSettings::new(src_root),
-            },
-        )
-        .expect("Valid search path settings");
-
-        db
-    }
-
-    #[track_caller]
-    fn get_function_f<'db>(db: &'db TestDb, file: &'static str) -> FunctionType<'db> {
-        let module = ruff_db::files::system_path_to_file(db, file).unwrap();
-        global_symbol(db, module, "f")
-            .expect_type()
-            .expect_function_literal()
-    }
-
-    #[track_caller]
-    fn assert_param_with_default<'db>(
-        db: &'db TestDb,
-        param_with_default: &ParameterWithDefault<'db>,
-        expected_name: &'static str,
-        expected_annotation_ty_display: &'static str,
-        expected_default_ty_display: Option<&'static str>,
-    ) {
-        assert_eq!(
-            param_with_default
-                .default_ty
-                .map(|ty| ty.display(db).to_string()),
-            expected_default_ty_display.map(ToString::to_string)
-        );
-        assert_param(
-            db,
-            &param_with_default.parameter,
-            expected_name,
-            expected_annotation_ty_display,
-        );
-    }
-
-    #[track_caller]
-    fn assert_param<'db>(
-        db: &'db TestDb,
-        param: &Parameter<'db>,
-        expected_name: &'static str,
-        expected_annotation_ty_display: &'static str,
-    ) {
-        assert_eq!(param.name.as_ref().unwrap(), expected_name);
-        assert_eq!(
-            param.annotated_ty.display(db).to_string(),
-            expected_annotation_ty_display
-        );
-    }
-
-    #[test]
-    fn empty() {
-        let mut db = setup_db();
-        db.write_dedented("/src/a.py", "def f(): ...").unwrap();
-        let func = get_function_f(&db, "/src/a.py");
-
-        let sig = func.internal_signature(&db);
-
-        assert_eq!(sig.return_ty.display(&db).to_string(), "Unknown");
-        let params = sig.parameters;
-        assert!(params.positional_only.is_empty());
-        assert!(params.positional_or_keyword.is_empty());
-        assert!(params.variadic.is_none());
-        assert!(params.keyword_only.is_empty());
-        assert!(params.keywords.is_none());
-    }
-
-    #[test]
-    #[allow(clippy::many_single_char_names)]
-    fn full() {
-        let mut db = setup_db();
-        db.write_dedented(
-            "/src/a.py",
-            "
-            def f(a, b: int, c = 1, d: int = 2, /,
-                  e = 3, f: Literal[4] = 4, *args: object,
-                  g = 5, h: Literal[6] = 6, **kwargs: str) -> bytes: ...
-            ",
-        )
-        .unwrap();
-        let func = get_function_f(&db, "/src/a.py");
-
-        let sig = func.internal_signature(&db);
-
-        assert_eq!(sig.return_ty.display(&db).to_string(), "bytes");
-        let params = sig.parameters;
-        let [a, b, c, d] = &params.positional_only[..] else {
-            panic!("expected four positional-only parameters");
-        };
-        let [e, f] = &params.positional_or_keyword[..] else {
-            panic!("expected two positional-or-keyword parameters");
-        };
-        let Some(args) = params.variadic else {
-            panic!("expected a variadic parameter");
-        };
-        let [g, h] = &params.keyword_only[..] else {
-            panic!("expected two keyword-only parameters");
-        };
-        let Some(kwargs) = params.keywords else {
-            panic!("expected a kwargs parameter");
-        };
-
-        assert_param_with_default(&db, a, "a", "Unknown", None);
-        assert_param_with_default(&db, b, "b", "int", None);
-        assert_param_with_default(&db, c, "c", "Unknown", Some("Literal[1]"));
-        assert_param_with_default(&db, d, "d", "int", Some("Literal[2]"));
-        assert_param_with_default(&db, e, "e", "Unknown", Some("Literal[3]"));
-        assert_param_with_default(&db, f, "f", "Literal[4]", Some("Literal[4]"));
-        assert_param_with_default(&db, g, "g", "Unknown", Some("Literal[5]"));
-        assert_param_with_default(&db, h, "h", "Literal[6]", Some("Literal[6]"));
-        assert_param(&db, &args, "args", "object");
-        assert_param(&db, &kwargs, "kwargs", "str");
-    }
-
-    #[test]
-    fn not_deferred() {
-        let mut db = setup_db();
-        db.write_dedented(
-            "/src/a.py",
-            "
-            class A: ...
-            class B: ...
-
-            alias = A
-
-            def f(a: alias): ...
-
-            alias = B
-            ",
-        )
-        .unwrap();
-        let func = get_function_f(&db, "/src/a.py");
-
-        let sig = func.internal_signature(&db);
-
-        let [a] = &sig.parameters.positional_or_keyword[..] else {
-            panic!("expected one positional-or-keyword parameter");
-        };
-        // Parameter resolution not deferred; we should see A not B
-        assert_param_with_default(&db, a, "a", "A", None);
-    }
-
-    #[test]
-    fn deferred_in_stub() {
-        let mut db = setup_db();
-        db.write_dedented(
-            "/src/a.pyi",
-            "
-            class A: ...
-            class B: ...
-
-            alias = A
-
-            def f(a: alias): ...
-
-            alias = B
-            ",
-        )
-        .unwrap();
-        let func = get_function_f(&db, "/src/a.pyi");
-
-        let sig = func.internal_signature(&db);
-
-        let [a] = &sig.parameters.positional_or_keyword[..] else {
-            panic!("expected one positional-or-keyword parameter");
-        };
-        // Parameter resolution deferred; we should see B
-        assert_param_with_default(&db, a, "a", "B", None);
-    }
-
-    #[test]
-    fn generic_not_deferred() {
-        let mut db = setup_db();
-        db.write_dedented(
-            "/src/a.py",
-            "
-            class A: ...
-            class B: ...
-
-            alias = A
-
-            def f[T](a: alias, b: T) -> T: ...
-
-            alias = B
-            ",
-        )
-        .unwrap();
-        let func = get_function_f(&db, "/src/a.py");
-
-        let sig = func.internal_signature(&db);
-
-        let [a, b] = &sig.parameters.positional_or_keyword[..] else {
-            panic!("expected two positional-or-keyword parameters");
-        };
-        // TODO resolution should not be deferred; we should see A not B
-        assert_param_with_default(&db, a, "a", "B", None);
-        assert_param_with_default(&db, b, "b", "T", None);
-    }
-
-    #[test]
-    fn generic_deferred_in_stub() {
-        let mut db = setup_db();
-        db.write_dedented(
-            "/src/a.pyi",
-            "
-            class A: ...
-            class B: ...
-
-            alias = A
-
-            def f[T](a: alias, b: T) -> T: ...
-
-            alias = B
-            ",
-        )
-        .unwrap();
-        let func = get_function_f(&db, "/src/a.pyi");
-
-        let sig = func.internal_signature(&db);
-
-        let [a, b] = &sig.parameters.positional_or_keyword[..] else {
-            panic!("expected two positional-or-keyword parameters");
-        };
-        // Parameter resolution deferred; we should see B
-        assert_param_with_default(&db, a, "a", "B", None);
-        assert_param_with_default(&db, b, "b", "T", None);
-    }
-
-    #[test]
-    fn external_signature_no_decorator() {
-        let mut db = setup_db();
-        db.write_dedented(
-            "/src/a.py",
-            "
-            def f(a: int) -> int: ...
-            ",
-        )
-        .unwrap();
-        let func = get_function_f(&db, "/src/a.py");
-
-        let expected_sig = func.internal_signature(&db);
-
-        // With no decorators, internal and external signature are the same
-        assert_eq!(func.signature(&db), &expected_sig);
-    }
-
-    #[test]
-    fn external_signature_decorated() {
-        let mut db = setup_db();
-        db.write_dedented(
-            "/src/a.py",
-            "
-            def deco(func): ...
-
-            @deco
-            def f(a: int) -> int: ...
-            ",
-        )
-        .unwrap();
-        let func = get_function_f(&db, "/src/a.py");
-
-        let expected_sig = Signature::todo();
-
-        // With no decorators, internal and external signature are the same
-        assert_eq!(func.signature(&db), &expected_sig);
-    }
-}

crates/red_knot_python_semantic/src/types/string_annotation.rs

@@ -1,77 +0,0 @@
-use ruff_db::files::File;
-use ruff_db::source::source_text;
-use ruff_python_ast::str::raw_contents;
-use ruff_python_ast::{self as ast, ModExpression, StringFlags};
-use ruff_python_parser::{parse_expression_range, Parsed};
-use ruff_text_size::Ranged;
-
-use crate::types::diagnostic::{TypeCheckDiagnostics, TypeCheckDiagnosticsBuilder};
-use crate::Db;
-
-type AnnotationParseResult = Result<Parsed<ModExpression>, TypeCheckDiagnostics>;
-
-/// Parses the given expression as a string annotation.
-pub(crate) fn parse_string_annotation(
-    db: &dyn Db,
-    file: File,
-    string_expr: &ast::ExprStringLiteral,
-) -> AnnotationParseResult {
-    let _span = tracing::trace_span!("parse_string_annotation", string=?string_expr.range(), file=%file.path(db)).entered();
-
-    let source = source_text(db.upcast(), file);
-    let node_text = &source[string_expr.range()];
-    let mut diagnostics = TypeCheckDiagnosticsBuilder::new(db, file);
-
-    if let [string_literal] = string_expr.value.as_slice() {
-        let prefix = string_literal.flags.prefix();
-        if prefix.is_raw() {
-            diagnostics.add(
-                string_literal.into(),
-                "annotation-raw-string",
-                format_args!("Type expressions cannot use raw string literal"),
-            );
-        // Compare the raw contents (without quotes) of the expression with the parsed contents
-        // contained in the string literal.
-        } else if raw_contents(node_text)
-            .is_some_and(|raw_contents| raw_contents == string_literal.as_str())
-        {
-            let range_excluding_quotes = string_literal
-                .range()
-                .add_start(string_literal.flags.opener_len())
-                .sub_end(string_literal.flags.closer_len());
-
-            // TODO: Support multiline strings like:
-            // ```py
-            // x: """
-            //     int
-            //     | float
-            // """ = 1
-            // ```
-            match parse_expression_range(source.as_str(), range_excluding_quotes) {
-                Ok(parsed) => return Ok(parsed),
-                Err(parse_error) => diagnostics.add(
-                    string_literal.into(),
-                    "forward-annotation-syntax-error",
-                    format_args!("Syntax error in forward annotation: {}", parse_error.error),
-                ),
-            }
-        } else {
-            // The raw contents of the string doesn't match the parsed content. This could be the
-            // case for annotations that contain escape sequences.
-            diagnostics.add(
-                string_expr.into(),
-                "annotation-escape-character",
-                format_args!("Type expressions cannot contain escape characters"),
-            );
-        }
-    } else {
-        // String is implicitly concatenated.
-        diagnostics.add(
-            string_expr.into(),
-            "annotation-implicit-concat",
-            format_args!("Type expressions cannot span multiple string literals"),
-        );
-    }
-
-    Err(diagnostics.finish())
-}

crates/red_knot_python_semantic/src/types/unpacker.rs

@@ -4,9 +4,9 @@ use ruff_db::files::File;
 use ruff_python_ast::{self as ast, AnyNodeRef};
 use rustc_hash::FxHashMap;
 
-use crate::semantic_index::ast_ids::{HasScopedExpressionId, ScopedExpressionId};
+use crate::semantic_index::ast_ids::{HasScopedAstId, ScopedExpressionId};
 use crate::semantic_index::symbol::ScopeId;
-use crate::types::{Type, TypeCheckDiagnostics, TypeCheckDiagnosticsBuilder};
+use crate::types::{TupleType, Type, TypeCheckDiagnostics, TypeCheckDiagnosticsBuilder};
 use crate::Db;
 
 /// Unpacks the value expression type to their respective targets.
@@ -29,7 +29,7 @@ impl<'db> Unpacker<'db> {
         match target {
             ast::Expr::Name(target_name) => {
                 self.targets
-                    .insert(target_name.scoped_expression_id(self.db, scope), value_ty);
+                    .insert(target_name.scoped_ast_id(self.db, scope), value_ty);
             }
             ast::Expr::Starred(ast::ExprStarred { value, .. }) => {
                 self.unpack(value, value_ty, scope);
@@ -93,10 +93,11 @@ impl<'db> Unpacker<'db> {
                     // further and deconstruct to an array of `StringLiteral` with each
                     // individual character, instead of just an array of `LiteralString`, but
                     // there would be a cost and it's not clear that it's worth it.
-                    let value_ty = Type::tuple(
+                    let value_ty = Type::Tuple(TupleType::new(
                         self.db,
-                        &vec![Type::LiteralString; string_literal_ty.len(self.db)],
-                    );
+                        vec![Type::LiteralString; string_literal_ty.len(self.db)]
+                            .into_boxed_slice(),
+                    ));
                     self.unpack(target, value_ty, scope);
                 }
                 _ => {

crates/red_knot_python_semantic/tests/mdtest.rs

@@ -1,7 +1,6 @@
-use std::ffi::OsStr;
-use std::path::Path;
-
 use dir_test::{dir_test, Fixture};
+use red_knot_test::run;
+use std::path::Path;
 
 /// See `crates/red_knot_test/README.md` for documentation on these tests.
 #[dir_test(
@@ -10,16 +9,16 @@ use dir_test::{dir_test, Fixture};
 )]
 #[allow(clippy::needless_pass_by_value)]
 fn mdtest(fixture: Fixture<&str>) {
-    let fixture_path = Path::new(fixture.path());
-    let crate_dir = Path::new(env!("CARGO_MANIFEST_DIR"));
-    let workspace_root = crate_dir.parent().and_then(Path::parent).unwrap();
+    let path = fixture.path();
 
-    let long_title = fixture_path
-        .strip_prefix(workspace_root)
-        .unwrap()
-        .to_str()
+    let crate_dir = Path::new(env!("CARGO_MANIFEST_DIR"))
+        .join("resources/mdtest")
+        .canonicalize()
         .unwrap();
-    let short_title = fixture_path.file_name().and_then(OsStr::to_str).unwrap();
 
-    red_knot_test::run(fixture_path, long_title, short_title);
+    let relative_path = path
+        .strip_prefix(crate_dir.to_str().unwrap())
+        .unwrap_or(path);
+
+    run(Path::new(path), relative_path);
 }

crates/red_knot_server/src/edit.rs

@@ -6,7 +6,7 @@ mod text_document;
 
 use lsp_types::{PositionEncodingKind, Url};
 pub use notebook::NotebookDocument;
-pub(crate) use range::{RangeExt, ToRangeExt};
+pub(crate) use range::RangeExt;
 pub(crate) use text_document::DocumentVersion;
 pub use text_document::TextDocument;
 

crates/red_knot_server/src/edit/range.rs

@@ -1,32 +1,13 @@
-use super::notebook;
 use super::PositionEncoding;
-use lsp_types as types;
-use ruff_notebook::NotebookIndex;
+use ruff_source_file::LineIndex;
 use ruff_source_file::OneIndexed;
-use ruff_source_file::{LineIndex, SourceLocation};
 use ruff_text_size::{TextRange, TextSize};
 
-pub(crate) struct NotebookRange {
-    pub(crate) cell: notebook::CellId,
-    pub(crate) range: types::Range,
-}
-
 pub(crate) trait RangeExt {
     fn to_text_range(&self, text: &str, index: &LineIndex, encoding: PositionEncoding)
         -> TextRange;
 }
 
-pub(crate) trait ToRangeExt {
-    fn to_range(&self, text: &str, index: &LineIndex, encoding: PositionEncoding) -> types::Range;
-    fn to_notebook_range(
-        &self,
-        text: &str,
-        source_index: &LineIndex,
-        notebook_index: &NotebookIndex,
-        encoding: PositionEncoding,
-    ) -> NotebookRange;
-}
-
 fn u32_index_to_usize(index: u32) -> usize {
     usize::try_from(index).expect("u32 fits in usize")
 }
@@ -94,61 +75,6 @@ impl RangeExt for lsp_types::Range {
     }
 }
 
-impl ToRangeExt for TextRange {
-    fn to_range(&self, text: &str, index: &LineIndex, encoding: PositionEncoding) -> types::Range {
-        types::Range {
-            start: source_location_to_position(&offset_to_source_location(
-                self.start(),
-                text,
-                index,
-                encoding,
-            )),
-            end: source_location_to_position(&offset_to_source_location(
-                self.end(),
-                text,
-                index,
-                encoding,
-            )),
-        }
-    }
-
-    fn to_notebook_range(
-        &self,
-        text: &str,
-        source_index: &LineIndex,
-        notebook_index: &NotebookIndex,
-        encoding: PositionEncoding,
-    ) -> NotebookRange {
-        let start = offset_to_source_location(self.start(), text, source_index, encoding);
-        let mut end = offset_to_source_location(self.end(), text, source_index, encoding);
-        let starting_cell = notebook_index.cell(start.row);
-
-        // weird edge case here - if the end of the range is where the newline after the cell got added (making it 'out of bounds')
-        // we need to move it one character back (which should place it at the end of the last line).
-        // we test this by checking if the ending offset is in a different (or nonexistent) cell compared to the cell of the starting offset.
-        if notebook_index.cell(end.row) != starting_cell {
-            end.row = end.row.saturating_sub(1);
-            end.column = offset_to_source_location(
-                self.end().checked_sub(1.into()).unwrap_or_default(),
-                text,
-                source_index,
-                encoding,
-            )
-            .column;
-        }
-
-        let start = source_location_to_position(&notebook_index.translate_location(&start));
-        let end = source_location_to_position(&notebook_index.translate_location(&end));
-
-        NotebookRange {
-            cell: starting_cell
-                .map(OneIndexed::to_zero_indexed)
-                .unwrap_or_default(),
-            range: types::Range { start, end },
-        }
-    }
-}
-
 /// Converts a UTF-16 code unit offset for a given line into a UTF-8 column number.
 fn utf8_column_offset(utf16_code_unit_offset: u32, line: &str) -> TextSize {
     let mut utf8_code_unit_offset = TextSize::new(0);
@@ -170,46 +96,3 @@ fn utf8_column_offset(utf16_code_unit_offset: u32, line: &str) -> TextSize {
 
     utf8_code_unit_offset
 }
-
-fn offset_to_source_location(
-    offset: TextSize,
-    text: &str,
-    index: &LineIndex,
-    encoding: PositionEncoding,
-) -> SourceLocation {
-    match encoding {
-        PositionEncoding::UTF8 => {
-            let row = index.line_index(offset);
-            let column = offset - index.line_start(row, text);
-
-            SourceLocation {
-                column: OneIndexed::from_zero_indexed(column.to_usize()),
-                row,
-            }
-        }
-        PositionEncoding::UTF16 => {
-            let row = index.line_index(offset);
-
-            let column = if index.is_ascii() {
-                (offset - index.line_start(row, text)).to_usize()
-            } else {
-                let up_to_line = &text[TextRange::new(index.line_start(row, text), offset)];
-                up_to_line.encode_utf16().count()
-            };
-
-            SourceLocation {
-                column: OneIndexed::from_zero_indexed(column),
-                row,
-            }
-        }
-        PositionEncoding::UTF32 => index.source_location(offset, text),
-    }
-}
-
-fn source_location_to_position(location: &SourceLocation) -> types::Position {
-    types::Position {
-        line: u32::try_from(location.row.to_zero_indexed()).expect("row usize fits in u32"),
-        character: u32::try_from(location.column.to_zero_indexed())
-            .expect("character usize fits in u32"),
-    }
-}

crates/red_knot_server/src/server/api/requests/diagnostic.rs

@@ -3,17 +3,15 @@ use std::borrow::Cow;
 use lsp_types::request::DocumentDiagnosticRequest;
 use lsp_types::{
     Diagnostic, DiagnosticSeverity, DocumentDiagnosticParams, DocumentDiagnosticReport,
-    DocumentDiagnosticReportResult, FullDocumentDiagnosticReport, NumberOrString, Range,
+    DocumentDiagnosticReportResult, FullDocumentDiagnosticReport, Position, Range,
     RelatedFullDocumentDiagnosticReport, Url,
 };
 
-use crate::edit::ToRangeExt;
+use red_knot_workspace::db::RootDatabase;
+
 use crate::server::api::traits::{BackgroundDocumentRequestHandler, RequestHandler};
 use crate::server::{client::Notifier, Result};
 use crate::session::DocumentSnapshot;
-use red_knot_workspace::db::{Db, RootDatabase};
-use ruff_db::diagnostic::Severity;
-use ruff_db::source::{line_index, source_text};
 
 pub(crate) struct DocumentDiagnosticRequestHandler;
 
@@ -66,37 +64,36 @@ fn compute_diagnostics(snapshot: &DocumentSnapshot, db: &RootDatabase) -> Vec<Di
     diagnostics
         .as_slice()
         .iter()
-        .map(|message| to_lsp_diagnostic(db, message, snapshot.encoding()))
+        .map(|message| to_lsp_diagnostic(message))
         .collect()
 }
 
-fn to_lsp_diagnostic(
-    db: &dyn Db,
-    diagnostic: &dyn ruff_db::diagnostic::Diagnostic,
-    encoding: crate::PositionEncoding,
-) -> Diagnostic {
-    let range = if let Some(range) = diagnostic.range() {
-        let index = line_index(db.upcast(), diagnostic.file());
-        let source = source_text(db.upcast(), diagnostic.file());
+fn to_lsp_diagnostic(message: &str) -> Diagnostic {
+    let words = message.split(':').collect::<Vec<_>>();
 
-        range.to_range(&source, &index, encoding)
-    } else {
-        Range::default()
-    };
-
-    let severity = match diagnostic.severity() {
-        Severity::Info => DiagnosticSeverity::INFORMATION,
-        Severity::Error => DiagnosticSeverity::ERROR,
+    let (range, message) = match words.as_slice() {
+        [_, _, line, column, message] | [_, line, column, message] => {
+            let line = line.parse::<u32>().unwrap_or_default().saturating_sub(1);
+            let column = column.parse::<u32>().unwrap_or_default();
+            (
+                Range::new(
+                    Position::new(line, column.saturating_sub(1)),
+                    Position::new(line, column),
+                ),
+                message.trim(),
+            )
+        }
+        _ => (Range::default(), message),
     };
 
     Diagnostic {
         range,
-        severity: Some(severity),
+        severity: Some(DiagnosticSeverity::ERROR),
         tags: None,
-        code: Some(NumberOrString::String(diagnostic.rule().to_string())),
+        code: None,
         code_description: None,
         source: Some("red-knot".into()),
-        message: diagnostic.message().into_owned(),
+        message: message.to_string(),
         related_information: None,
         data: None,
     }

crates/red_knot_server/src/session.rs

@@ -68,7 +68,7 @@ impl Session {
             let system = LSPSystem::new(index.clone());
 
             // TODO(dhruvmanila): Get the values from the client settings
-            let metadata = WorkspaceMetadata::discover(system_path, &system, None)?;
+            let metadata = WorkspaceMetadata::from_path(system_path, &system, None)?;
             // TODO(micha): Handle the case where the program settings are incorrect more gracefully.
             workspaces.insert(path, RootDatabase::new(metadata, system)?);
         }

crates/red_knot_server/src/system.rs

@@ -7,8 +7,8 @@ use lsp_types::Url;
 use ruff_db::file_revision::FileRevision;
 use ruff_db::system::walk_directory::WalkDirectoryBuilder;
 use ruff_db::system::{
-    DirectoryEntry, FileType, GlobError, Metadata, OsSystem, PatternError, Result, System,
-    SystemPath, SystemPathBuf, SystemVirtualPath, SystemVirtualPathBuf,
+    DirectoryEntry, FileType, Metadata, OsSystem, Result, System, SystemPath, SystemPathBuf,
+    SystemVirtualPath, SystemVirtualPathBuf,
 };
 use ruff_notebook::{Notebook, NotebookError};
 
@@ -198,16 +198,6 @@ impl System for LSPSystem {
         self.os_system.walk_directory(path)
     }
 
-    fn glob(
-        &self,
-        pattern: &str,
-    ) -> std::result::Result<
-        Box<dyn Iterator<Item = std::result::Result<SystemPathBuf, GlobError>>>,
-        PatternError,
-    > {
-        self.os_system.glob(pattern)
-    }
-
     fn as_any(&self) -> &dyn Any {
         self
     }

crates/red_knot_test/Cargo.toml

@@ -15,6 +15,7 @@ red_knot_python_semantic = { workspace = true }
 red_knot_vendored = { workspace = true }
 ruff_db = { workspace = true }
 ruff_index = { workspace = true }
+ruff_python_parser = { workspace = true }
 ruff_python_trivia = { workspace = true }
 ruff_source_file = { workspace = true }
 ruff_text_size = { workspace = true }

crates/red_knot_test/src/diagnostic.rs

@@ -2,10 +2,63 @@
 //!
 //! We don't assume that we will get the diagnostics in source order.
 
-use ruff_db::diagnostic::Diagnostic;
+use red_knot_python_semantic::types::TypeCheckDiagnostic;
+use ruff_python_parser::ParseError;
 use ruff_source_file::{LineIndex, OneIndexed};
+use ruff_text_size::{Ranged, TextRange};
+use std::borrow::Cow;
 use std::ops::{Deref, Range};
 
+pub(super) trait Diagnostic: std::fmt::Debug {
+    fn rule(&self) -> &str;
+
+    fn message(&self) -> Cow<str>;
+
+    fn range(&self) -> TextRange;
+}
+
+impl Diagnostic for TypeCheckDiagnostic {
+    fn rule(&self) -> &str {
+        TypeCheckDiagnostic::rule(self)
+    }
+
+    fn message(&self) -> Cow<str> {
+        TypeCheckDiagnostic::message(self).into()
+    }
+
+    fn range(&self) -> TextRange {
+        Ranged::range(self)
+    }
+}
+
+impl Diagnostic for ParseError {
+    fn rule(&self) -> &str {
+        "invalid-syntax"
+    }
+
+    fn message(&self) -> Cow<str> {
+        self.error.to_string().into()
+    }
+
+    fn range(&self) -> TextRange {
+        self.location
+    }
+}
+
+impl Diagnostic for Box<dyn Diagnostic> {
+    fn rule(&self) -> &str {
+        (**self).rule()
+    }
+
+    fn message(&self) -> Cow<str> {
+        (**self).message()
+    }
+
+    fn range(&self) -> TextRange {
+        (**self).range()
+    }
+}
+
 /// All diagnostics for one embedded Python file, sorted and grouped by start line number.
 ///
 /// The diagnostics are kept in a flat vector, sorted by line number. A separate vector of
@@ -25,11 +78,7 @@ where
         let mut diagnostics: Vec<_> = diagnostics
             .into_iter()
             .map(|diagnostic| DiagnosticWithLine {
-                line_number: diagnostic
-                    .range()
-                    .map_or(OneIndexed::from_zero_indexed(0), |range| {
-                        line_index.line_index(range.start())
-                    }),
+                line_number: line_index.line_index(diagnostic.range().start()),
                 diagnostic,
             })
             .collect();
@@ -144,8 +193,7 @@ struct DiagnosticWithLine<T> {
 mod tests {
     use crate::db::Db;
     use crate::diagnostic::Diagnostic;
-    use ruff_db::diagnostic::Severity;
-    use ruff_db::files::{system_path_to_file, File};
+    use ruff_db::files::system_path_to_file;
     use ruff_db::source::line_index;
     use ruff_db::system::{DbWithTestSystem, SystemPathBuf};
     use ruff_source_file::OneIndexed;
@@ -167,7 +215,7 @@ mod tests {
 
         let diagnostics: Vec<_> = ranges
             .into_iter()
-            .map(|range| DummyDiagnostic { range, file })
+            .map(|range| DummyDiagnostic { range })
             .collect();
 
         let sorted = super::SortedDiagnostics::new(diagnostics, &lines);
@@ -186,7 +234,6 @@ mod tests {
     #[derive(Debug)]
     struct DummyDiagnostic {
         range: TextRange,
-        file: File,
     }
 
     impl Diagnostic for DummyDiagnostic {
@@ -198,16 +245,8 @@ mod tests {
             "dummy".into()
         }
 
-        fn file(&self) -> File {
-            self.file
-        }
-
-        fn range(&self) -> Option<TextRange> {
-            Some(self.range)
-        }
-
-        fn severity(&self) -> Severity {
-            Severity::Error
+        fn range(&self) -> TextRange {
+            self.range
         }
     }
 }

crates/red_knot_test/src/lib.rs

@@ -1,13 +1,14 @@
+use crate::diagnostic::Diagnostic;
 use colored::Colorize;
 use parser as test_parser;
 use red_knot_python_semantic::types::check_types;
-use ruff_db::diagnostic::{Diagnostic, ParseDiagnostic};
 use ruff_db::files::{system_path_to_file, File, Files};
 use ruff_db::parsed::parsed_module;
 use ruff_db::system::{DbWithTestSystem, SystemPathBuf};
 use ruff_source_file::LineIndex;
 use ruff_text_size::TextSize;
 use std::path::Path;
+use std::sync::Arc;
 
 mod assertion;
 mod db;
@@ -19,9 +20,9 @@ mod parser;
 ///
 /// Panic on test failure, and print failure details.
 #[allow(clippy::print_stdout)]
-pub fn run(path: &Path, long_title: &str, short_title: &str) {
+pub fn run(path: &Path, title: &str) {
     let source = std::fs::read_to_string(path).unwrap();
-    let suite = match test_parser::parse(short_title, &source) {
+    let suite = match test_parser::parse(title, &source) {
         Ok(suite) => suite,
         Err(err) => {
             panic!("Error parsing `{}`: {err}", path.to_str().unwrap())
@@ -49,8 +50,8 @@ pub fn run(path: &Path, long_title: &str, short_title: &str) {
                     for failure in failures {
                         let absolute_line_number =
                             backtick_line.checked_add(relative_line_number).unwrap();
-                        let line_info = format!("{long_title}:{absolute_line_number}").cyan();
-                        println!("  {line_info} {failure}");
+                        let line_info = format!("{title}:{absolute_line_number}").cyan();
+                        println!("    {line_info} {failure}");
                     }
                 }
             }
@@ -93,15 +94,14 @@ fn run_test(db: &mut db::Db, test: &parser::MarkdownTest) -> Result<(), Failures
                 .iter()
                 .cloned()
                 .map(|error| {
-                    let diagnostic: Box<dyn Diagnostic> =
-                        Box::new(ParseDiagnostic::new(test_file.file, error));
+                    let diagnostic: Box<dyn Diagnostic> = Box::new(error);
                     diagnostic
                 })
                 .collect();
 
             let type_diagnostics = check_types(db, test_file.file);
             diagnostics.extend(type_diagnostics.into_iter().map(|diagnostic| {
-                let diagnostic: Box<dyn Diagnostic> = Box::new((*diagnostic).clone());
+                let diagnostic: Box<dyn Diagnostic> = Box::new(Arc::unwrap_or_clone(diagnostic));
                 diagnostic
             }));
 

crates/red_knot_test/src/matcher.rs

@@ -2,9 +2,8 @@
 //! mismatches.
 use crate::assertion::{Assertion, ErrorAssertion, InlineFileAssertions};
 use crate::db::Db;
-use crate::diagnostic::SortedDiagnostics;
+use crate::diagnostic::{Diagnostic, SortedDiagnostics};
 use colored::Colorize;
-use ruff_db::diagnostic::Diagnostic;
 use ruff_db::files::File;
 use ruff_db::source::{line_index, source_text, SourceText};
 use ruff_source_file::{LineIndex, OneIndexed};
@@ -236,14 +235,9 @@ impl Matcher {
     }
 
     fn column<T: Diagnostic>(&self, diagnostic: &T) -> OneIndexed {
-        diagnostic
-            .range()
-            .map(|range| {
-                self.line_index
-                    .source_location(range.start(), &self.source)
-                    .column
-            })
-            .unwrap_or(OneIndexed::from_zero_indexed(0))
+        self.line_index
+            .source_location(diagnostic.range().start(), &self.source)
+            .column
     }
 
     /// Check if `assertion` matches any [`Diagnostic`]s in `unmatched`.
@@ -310,21 +304,22 @@ impl Matcher {
 #[cfg(test)]
 mod tests {
     use super::FailuresByLine;
-    use ruff_db::diagnostic::{Diagnostic, Severity};
-    use ruff_db::files::{system_path_to_file, File};
+    use crate::diagnostic::Diagnostic;
+    use ruff_db::files::system_path_to_file;
     use ruff_db::system::{DbWithTestSystem, SystemPathBuf};
     use ruff_python_trivia::textwrap::dedent;
     use ruff_source_file::OneIndexed;
     use ruff_text_size::TextRange;
     use std::borrow::Cow;
 
-    struct ExpectedDiagnostic {
+    #[derive(Clone, Debug)]
+    struct TestDiagnostic {
         rule: &'static str,
         message: &'static str,
         range: TextRange,
     }
 
-    impl ExpectedDiagnostic {
+    impl TestDiagnostic {
         fn new(rule: &'static str, message: &'static str, offset: usize) -> Self {
             let offset: u32 = offset.try_into().unwrap();
             Self {
@@ -333,23 +328,6 @@ mod tests {
                 range: TextRange::new(offset.into(), (offset + 1).into()),
             }
         }
-
-        fn into_diagnostic(self, file: File) -> TestDiagnostic {
-            TestDiagnostic {
-                rule: self.rule,
-                message: self.message,
-                range: self.range,
-                file,
-            }
-        }
-    }
-
-    #[derive(Debug)]
-    struct TestDiagnostic {
-        rule: &'static str,
-        message: &'static str,
-        range: TextRange,
-        file: File,
     }
 
     impl Diagnostic for TestDiagnostic {
@@ -361,36 +339,19 @@ mod tests {
             self.message.into()
         }
 
-        fn file(&self) -> File {
-            self.file
-        }
-
-        fn range(&self) -> Option<TextRange> {
-            Some(self.range)
-        }
-
-        fn severity(&self) -> Severity {
-            Severity::Error
+        fn range(&self) -> TextRange {
+            self.range
         }
     }
 
-    fn get_result(
-        source: &str,
-        diagnostics: Vec<ExpectedDiagnostic>,
-    ) -> Result<(), FailuresByLine> {
+    fn get_result(source: &str, diagnostics: Vec<TestDiagnostic>) -> Result<(), FailuresByLine> {
         colored::control::set_override(false);
 
         let mut db = crate::db::Db::setup(SystemPathBuf::from("/src"));
         db.write_file("/src/test.py", source).unwrap();
         let file = system_path_to_file(&db, "/src/test.py").unwrap();
 
-        super::match_file(
-            &db,
-            file,
-            diagnostics
-                .into_iter()
-                .map(|diagnostic| diagnostic.into_diagnostic(file)),
-        )
+        super::match_file(&db, file, diagnostics)
     }
 
     fn assert_fail(result: Result<(), FailuresByLine>, messages: &[(usize, &[&str])]) {
@@ -423,7 +384,7 @@ mod tests {
     fn revealed_match() {
         let result = get_result(
             "x # revealed: Foo",
-            vec![ExpectedDiagnostic::new(
+            vec![TestDiagnostic::new(
                 "revealed-type",
                 "Revealed type is `Foo`",
                 0,
@@ -437,7 +398,7 @@ mod tests {
     fn revealed_wrong_rule() {
         let result = get_result(
             "x # revealed: Foo",
-            vec![ExpectedDiagnostic::new(
+            vec![TestDiagnostic::new(
                 "not-revealed-type",
                 "Revealed type is `Foo`",
                 0,
@@ -460,11 +421,7 @@ mod tests {
     fn revealed_wrong_message() {
         let result = get_result(
             "x # revealed: Foo",
-            vec![ExpectedDiagnostic::new(
-                "revealed-type",
-                "Something else",
-                0,
-            )],
+            vec![TestDiagnostic::new("revealed-type", "Something else", 0)],
         );
 
         assert_fail(
@@ -491,8 +448,8 @@ mod tests {
         let result = get_result(
             "x # revealed: Foo",
             vec![
-                ExpectedDiagnostic::new("revealed-type", "Revealed type is `Foo`", 0),
-                ExpectedDiagnostic::new("undefined-reveal", "Doesn't matter", 0),
+                TestDiagnostic::new("revealed-type", "Revealed type is `Foo`", 0),
+                TestDiagnostic::new("undefined-reveal", "Doesn't matter", 0),
             ],
         );
 
@@ -503,11 +460,7 @@ mod tests {
     fn revealed_match_with_only_undefined() {
         let result = get_result(
             "x # revealed: Foo",
-            vec![ExpectedDiagnostic::new(
-                "undefined-reveal",
-                "Doesn't matter",
-                0,
-            )],
+            vec![TestDiagnostic::new("undefined-reveal", "Doesn't matter", 0)],
         );
 
         assert_fail(result, &[(0, &["unmatched assertion: revealed: Foo"])]);
@@ -518,8 +471,8 @@ mod tests {
         let result = get_result(
             "x # revealed: Foo",
             vec![
-                ExpectedDiagnostic::new("revealed-type", "Revealed type is `Bar`", 0),
-                ExpectedDiagnostic::new("undefined-reveal", "Doesn't matter", 0),
+                TestDiagnostic::new("revealed-type", "Revealed type is `Bar`", 0),
+                TestDiagnostic::new("undefined-reveal", "Doesn't matter", 0),
             ],
         );
 
@@ -540,8 +493,8 @@ mod tests {
         let result = get_result(
             "reveal_type(1)",
             vec![
-                ExpectedDiagnostic::new("undefined-reveal", "undefined reveal message", 0),
-                ExpectedDiagnostic::new("revealed-type", "Revealed type is `Literal[1]`", 12),
+                TestDiagnostic::new("undefined-reveal", "undefined reveal message", 0),
+                TestDiagnostic::new("revealed-type", "Revealed type is `Literal[1]`", 12),
             ],
         );
 
@@ -563,8 +516,8 @@ mod tests {
         let result = get_result(
             "reveal_type(1) # error: [something-else]",
             vec![
-                ExpectedDiagnostic::new("undefined-reveal", "undefined reveal message", 0),
-                ExpectedDiagnostic::new("revealed-type", "Revealed type is `Literal[1]`", 12),
+                TestDiagnostic::new("undefined-reveal", "undefined reveal message", 0),
+                TestDiagnostic::new("revealed-type", "Revealed type is `Literal[1]`", 12),
             ],
         );
 
@@ -593,7 +546,7 @@ mod tests {
     fn error_match_rule() {
         let result = get_result(
             "x # error: [some-rule]",
-            vec![ExpectedDiagnostic::new("some-rule", "Any message", 0)],
+            vec![TestDiagnostic::new("some-rule", "Any message", 0)],
         );
 
         assert_ok(&result);
@@ -603,7 +556,7 @@ mod tests {
     fn error_wrong_rule() {
         let result = get_result(
             "x # error: [some-rule]",
-            vec![ExpectedDiagnostic::new("anything", "Any message", 0)],
+            vec![TestDiagnostic::new("anything", "Any message", 0)],
         );
 
         assert_fail(
@@ -622,11 +575,7 @@ mod tests {
     fn error_match_message() {
         let result = get_result(
             r#"x # error: "contains this""#,
-            vec![ExpectedDiagnostic::new(
-                "anything",
-                "message contains this",
-                0,
-            )],
+            vec![TestDiagnostic::new("anything", "message contains this", 0)],
         );
 
         assert_ok(&result);
@@ -636,7 +585,7 @@ mod tests {
     fn error_wrong_message() {
         let result = get_result(
             r#"x # error: "contains this""#,
-            vec![ExpectedDiagnostic::new("anything", "Any message", 0)],
+            vec![TestDiagnostic::new("anything", "Any message", 0)],
         );
 
         assert_fail(
@@ -655,7 +604,7 @@ mod tests {
     fn error_match_column_and_rule() {
         let result = get_result(
             "x # error: 1 [some-rule]",
-            vec![ExpectedDiagnostic::new("some-rule", "Any message", 0)],
+            vec![TestDiagnostic::new("some-rule", "Any message", 0)],
         );
 
         assert_ok(&result);
@@ -665,7 +614,7 @@ mod tests {
     fn error_wrong_column() {
         let result = get_result(
             "x # error: 2 [rule]",
-            vec![ExpectedDiagnostic::new("rule", "Any message", 0)],
+            vec![TestDiagnostic::new("rule", "Any message", 0)],
         );
 
         assert_fail(
@@ -684,11 +633,7 @@ mod tests {
     fn error_match_column_and_message() {
         let result = get_result(
             r#"x # error: 1 "contains this""#,
-            vec![ExpectedDiagnostic::new(
-                "anything",
-                "message contains this",
-                0,
-            )],
+            vec![TestDiagnostic::new("anything", "message contains this", 0)],
         );
 
         assert_ok(&result);
@@ -698,11 +643,7 @@ mod tests {
     fn error_match_rule_and_message() {
         let result = get_result(
             r#"x # error: [a-rule] "contains this""#,
-            vec![ExpectedDiagnostic::new(
-                "a-rule",
-                "message contains this",
-                0,
-            )],
+            vec![TestDiagnostic::new("a-rule", "message contains this", 0)],
         );
 
         assert_ok(&result);
@@ -712,11 +653,7 @@ mod tests {
     fn error_match_all() {
         let result = get_result(
             r#"x # error: 1 [a-rule] "contains this""#,
-            vec![ExpectedDiagnostic::new(
-                "a-rule",
-                "message contains this",
-                0,
-            )],
+            vec![TestDiagnostic::new("a-rule", "message contains this", 0)],
         );
 
         assert_ok(&result);
@@ -726,11 +663,7 @@ mod tests {
     fn error_match_all_wrong_column() {
         let result = get_result(
             r#"x # error: 2 [some-rule] "contains this""#,
-            vec![ExpectedDiagnostic::new(
-                "some-rule",
-                "message contains this",
-                0,
-            )],
+            vec![TestDiagnostic::new("some-rule", "message contains this", 0)],
         );
 
         assert_fail(
@@ -749,7 +682,7 @@ mod tests {
     fn error_match_all_wrong_rule() {
         let result = get_result(
             r#"x # error: 1 [some-rule] "contains this""#,
-            vec![ExpectedDiagnostic::new(
+            vec![TestDiagnostic::new(
                 "other-rule",
                 "message contains this",
                 0,
@@ -772,7 +705,7 @@ mod tests {
     fn error_match_all_wrong_message() {
         let result = get_result(
             r#"x # error: 1 [some-rule] "contains this""#,
-            vec![ExpectedDiagnostic::new("some-rule", "Any message", 0)],
+            vec![TestDiagnostic::new("some-rule", "Any message", 0)],
         );
 
         assert_fail(
@@ -805,9 +738,9 @@ mod tests {
         let result = get_result(
             &source,
             vec![
-                ExpectedDiagnostic::new("line-two", "msg", two),
-                ExpectedDiagnostic::new("line-three", "msg", three),
-                ExpectedDiagnostic::new("line-five", "msg", five),
+                TestDiagnostic::new("line-two", "msg", two),
+                TestDiagnostic::new("line-three", "msg", three),
+                TestDiagnostic::new("line-five", "msg", five),
             ],
         );
 
@@ -836,8 +769,8 @@ mod tests {
         let result = get_result(
             &source,
             vec![
-                ExpectedDiagnostic::new("line-one", "msg", one),
-                ExpectedDiagnostic::new("line-two", "msg", two),
+                TestDiagnostic::new("line-one", "msg", one),
+                TestDiagnostic::new("line-two", "msg", two),
             ],
         );
 
@@ -857,8 +790,8 @@ mod tests {
         let result = get_result(
             &source,
             vec![
-                ExpectedDiagnostic::new("one-rule", "msg", x),
-                ExpectedDiagnostic::new("other-rule", "msg", x),
+                TestDiagnostic::new("one-rule", "msg", x),
+                TestDiagnostic::new("other-rule", "msg", x),
             ],
         );
 
@@ -878,8 +811,8 @@ mod tests {
         let result = get_result(
             &source,
             vec![
-                ExpectedDiagnostic::new("one-rule", "msg", x),
-                ExpectedDiagnostic::new("one-rule", "msg", x),
+                TestDiagnostic::new("one-rule", "msg", x),
+                TestDiagnostic::new("one-rule", "msg", x),
             ],
         );
 
@@ -899,9 +832,9 @@ mod tests {
         let result = get_result(
             &source,
             vec![
-                ExpectedDiagnostic::new("one-rule", "msg", x),
-                ExpectedDiagnostic::new("other-rule", "msg", x),
-                ExpectedDiagnostic::new("third-rule", "msg", x),
+                TestDiagnostic::new("one-rule", "msg", x),
+                TestDiagnostic::new("other-rule", "msg", x),
+                TestDiagnostic::new("third-rule", "msg", x),
             ],
         );
 
@@ -925,8 +858,8 @@ mod tests {
         let result = get_result(
             &source,
             vec![
-                ExpectedDiagnostic::new("undefined-reveal", "msg", reveal),
-                ExpectedDiagnostic::new("revealed-type", "Revealed type is `Literal[5]`", reveal),
+                TestDiagnostic::new("undefined-reveal", "msg", reveal),
+                TestDiagnostic::new("revealed-type", "Revealed type is `Literal[5]`", reveal),
             ],
         );
 
@@ -939,7 +872,7 @@ mod tests {
         let x = source.find('x').unwrap();
         let result = get_result(
             source,
-            vec![ExpectedDiagnostic::new("some-rule", "some message", x)],
+            vec![TestDiagnostic::new("some-rule", "some message", x)],
         );
 
         assert_fail(
@@ -960,7 +893,7 @@ mod tests {
         let x = source.find('x').unwrap();
         let result = get_result(
             source,
-            vec![ExpectedDiagnostic::new("some-rule", "some message", x)],
+            vec![TestDiagnostic::new("some-rule", "some message", x)],
         );
 
         assert_fail(

crates/red_knot_vendored/vendor/typeshed/source_commit.txt

@@ -1 +1 @@
-5052fa2f18db4493892e0f2775030683c9d06531
+d262beb07502cda412db2179fb406d45d1a9486f

crates/red_knot_vendored/vendor/typeshed/stdlib/VERSIONS

@@ -24,22 +24,18 @@ _asyncio: 3.0-
 _bisect: 3.0-
 _blake2: 3.6-
 _bootlocale: 3.4-3.9
-_bz2: 3.3-
 _codecs: 3.0-
 _collections_abc: 3.3-
 _compat_pickle: 3.1-
 _compression: 3.5-
-_contextvars: 3.7-
 _csv: 3.0-
 _ctypes: 3.0-
 _curses: 3.0-
-_dbm: 3.0-
 _decimal: 3.3-
 _dummy_thread: 3.0-3.8
 _dummy_threading: 3.0-3.8
 _frozen_importlib: 3.0-
 _frozen_importlib_external: 3.5-
-_gdbm: 3.0-
 _heapq: 3.0-
 _imp: 3.0-
 _interpchannels: 3.13-
@@ -49,7 +45,6 @@ _io: 3.0-
 _json: 3.0-
 _locale: 3.0-
 _lsprof: 3.0-
-_lzma: 3.3-
 _markupbase: 3.0-
 _msi: 3.0-3.12
 _operator: 3.4-
@@ -57,14 +52,12 @@ _osx_support: 3.0-
 _posixsubprocess: 3.2-
 _py_abc: 3.7-
 _pydecimal: 3.5-
-_queue: 3.7-
 _random: 3.0-
 _sitebuiltins: 3.4-
 _socket: 3.0-  # present in 3.0 at runtime, but not in typeshed
 _sqlite3: 3.0-
 _ssl: 3.0-
 _stat: 3.4-
-_struct: 3.0-
 _thread: 3.0-
 _threading_local: 3.0-
 _tkinter: 3.0-

crates/red_knot_vendored/vendor/typeshed/stdlib/_bz2.pyi

@@ -1,18 +0,0 @@
-from _typeshed import ReadableBuffer
-from typing import final
-
-@final
-class BZ2Compressor:
-    def __init__(self, compresslevel: int = 9) -> None: ...
-    def compress(self, data: ReadableBuffer, /) -> bytes: ...
-    def flush(self) -> bytes: ...
-
-@final
-class BZ2Decompressor:
-    def decompress(self, data: ReadableBuffer, max_length: int = -1) -> bytes: ...
-    @property
-    def eof(self) -> bool: ...
-    @property
-    def needs_input(self) -> bool: ...
-    @property
-    def unused_data(self) -> bytes: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/_contextvars.pyi

@@ -1,61 +0,0 @@
-import sys
-from collections.abc import Callable, Iterator, Mapping
-from typing import Any, ClassVar, Generic, TypeVar, final, overload
-from typing_extensions import ParamSpec
-
-if sys.version_info >= (3, 9):
-    from types import GenericAlias
-
-_T = TypeVar("_T")
-_D = TypeVar("_D")
-_P = ParamSpec("_P")
-
-@final
-class ContextVar(Generic[_T]):
-    @overload
-    def __init__(self, name: str) -> None: ...
-    @overload
-    def __init__(self, name: str, *, default: _T) -> None: ...
-    def __hash__(self) -> int: ...
-    @property
-    def name(self) -> str: ...
-    @overload
-    def get(self) -> _T: ...
-    @overload
-    def get(self, default: _T, /) -> _T: ...
-    @overload
-    def get(self, default: _D, /) -> _D | _T: ...
-    def set(self, value: _T, /) -> Token[_T]: ...
-    def reset(self, token: Token[_T], /) -> None: ...
-    if sys.version_info >= (3, 9):
-        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
-
-@final
-class Token(Generic[_T]):
-    @property
-    def var(self) -> ContextVar[_T]: ...
-    @property
-    def old_value(self) -> Any: ...  # returns either _T or MISSING, but that's hard to express
-    MISSING: ClassVar[object]
-    if sys.version_info >= (3, 9):
-        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
-
-def copy_context() -> Context: ...
-
-# It doesn't make sense to make this generic, because for most Contexts each ContextVar will have
-# a different value.
-@final
-class Context(Mapping[ContextVar[Any], Any]):
-    def __init__(self) -> None: ...
-    @overload
-    def get(self, key: ContextVar[_T], default: None = None, /) -> _T | None: ...
-    @overload
-    def get(self, key: ContextVar[_T], default: _T, /) -> _T: ...
-    @overload
-    def get(self, key: ContextVar[_T], default: _D, /) -> _T | _D: ...
-    def run(self, callable: Callable[_P, _T], *args: _P.args, **kwargs: _P.kwargs) -> _T: ...
-    def copy(self) -> Context: ...
-    def __getitem__(self, key: ContextVar[_T], /) -> _T: ...
-    def __iter__(self) -> Iterator[ContextVar[Any]]: ...
-    def __len__(self) -> int: ...
-    def __eq__(self, value: object, /) -> bool: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/_dbm.pyi

@@ -1,43 +0,0 @@
-import sys
-from _typeshed import ReadOnlyBuffer, StrOrBytesPath
-from types import TracebackType
-from typing import TypeVar, overload
-from typing_extensions import Self, TypeAlias
-
-if sys.platform != "win32":
-    _T = TypeVar("_T")
-    _KeyType: TypeAlias = str | ReadOnlyBuffer
-    _ValueType: TypeAlias = str | ReadOnlyBuffer
-
-    class error(OSError): ...
-    library: str
-
-    # Actual typename dbm, not exposed by the implementation
-    class _dbm:
-        def close(self) -> None: ...
-        if sys.version_info >= (3, 13):
-            def clear(self) -> None: ...
-
-        def __getitem__(self, item: _KeyType) -> bytes: ...
-        def __setitem__(self, key: _KeyType, value: _ValueType) -> None: ...
-        def __delitem__(self, key: _KeyType) -> None: ...
-        def __len__(self) -> int: ...
-        def __del__(self) -> None: ...
-        def __enter__(self) -> Self: ...
-        def __exit__(
-            self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
-        ) -> None: ...
-        @overload
-        def get(self, k: _KeyType) -> bytes | None: ...
-        @overload
-        def get(self, k: _KeyType, default: _T) -> bytes | _T: ...
-        def keys(self) -> list[bytes]: ...
-        def setdefault(self, k: _KeyType, default: _ValueType = ...) -> bytes: ...
-        # Don't exist at runtime
-        __new__: None  # type: ignore[assignment]
-        __init__: None  # type: ignore[assignment]
-
-    if sys.version_info >= (3, 11):
-        def open(filename: StrOrBytesPath, flags: str = "r", mode: int = 0o666, /) -> _dbm: ...
-    else:
-        def open(filename: str, flags: str = "r", mode: int = 0o666, /) -> _dbm: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/_frozen_importlib_external.pyi

@@ -107,9 +107,9 @@ class FileLoader:
     def get_filename(self, name: str | None = None) -> str: ...
     def load_module(self, name: str | None = None) -> types.ModuleType: ...
     if sys.version_info >= (3, 10):
-        def get_resource_reader(self, name: str | None = None) -> importlib.readers.FileReader: ...
+        def get_resource_reader(self, module: types.ModuleType) -> importlib.readers.FileReader: ...
     else:
-        def get_resource_reader(self, name: str | None = None) -> Self | None: ...
+        def get_resource_reader(self, module: types.ModuleType) -> Self | None: ...
         def open_resource(self, resource: str) -> _io.FileIO: ...
         def resource_path(self, resource: str) -> str: ...
         def is_resource(self, name: str) -> bool: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/_gdbm.pyi

@@ -1,47 +0,0 @@
-import sys
-from _typeshed import ReadOnlyBuffer, StrOrBytesPath
-from types import TracebackType
-from typing import TypeVar, overload
-from typing_extensions import Self, TypeAlias
-
-if sys.platform != "win32":
-    _T = TypeVar("_T")
-    _KeyType: TypeAlias = str | ReadOnlyBuffer
-    _ValueType: TypeAlias = str | ReadOnlyBuffer
-
-    open_flags: str
-
-    class error(OSError): ...
-    # Actual typename gdbm, not exposed by the implementation
-    class _gdbm:
-        def firstkey(self) -> bytes | None: ...
-        def nextkey(self, key: _KeyType) -> bytes | None: ...
-        def reorganize(self) -> None: ...
-        def sync(self) -> None: ...
-        def close(self) -> None: ...
-        if sys.version_info >= (3, 13):
-            def clear(self) -> None: ...
-
-        def __getitem__(self, item: _KeyType) -> bytes: ...
-        def __setitem__(self, key: _KeyType, value: _ValueType) -> None: ...
-        def __delitem__(self, key: _KeyType) -> None: ...
-        def __contains__(self, key: _KeyType) -> bool: ...
-        def __len__(self) -> int: ...
-        def __enter__(self) -> Self: ...
-        def __exit__(
-            self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
-        ) -> None: ...
-        @overload
-        def get(self, k: _KeyType) -> bytes | None: ...
-        @overload
-        def get(self, k: _KeyType, default: _T) -> bytes | _T: ...
-        def keys(self) -> list[bytes]: ...
-        def setdefault(self, k: _KeyType, default: _ValueType = ...) -> bytes: ...
-        # Don't exist at runtime
-        __new__: None  # type: ignore[assignment]
-        __init__: None  # type: ignore[assignment]
-
-    if sys.version_info >= (3, 11):
-        def open(filename: StrOrBytesPath, flags: str = "r", mode: int = 0o666, /) -> _gdbm: ...
-    else:
-        def open(filename: str, flags: str = "r", mode: int = 0o666, /) -> _gdbm: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/_io.pyi

@@ -33,10 +33,10 @@ class _IOBase:
     def readable(self) -> bool: ...
     read: Callable[..., Any]
     def readlines(self, hint: int = -1, /) -> list[bytes]: ...
-    def seek(self, offset: int, whence: int = 0, /) -> int: ...
+    def seek(self, offset: int, whence: int = ..., /) -> int: ...
     def seekable(self) -> bool: ...
     def tell(self) -> int: ...
-    def truncate(self, size: int | None = None, /) -> int: ...
+    def truncate(self, size: int | None = ..., /) -> int: ...
     def writable(self) -> bool: ...
     write: Callable[..., Any]
     def writelines(self, lines: Iterable[ReadableBuffer], /) -> None: ...
@@ -59,8 +59,8 @@ class _BufferedIOBase(_IOBase):
     def readinto(self, buffer: WriteableBuffer, /) -> int: ...
     def write(self, buffer: ReadableBuffer, /) -> int: ...
     def readinto1(self, buffer: WriteableBuffer, /) -> int: ...
-    def read(self, size: int | None = -1, /) -> bytes: ...
-    def read1(self, size: int = -1, /) -> bytes: ...
+    def read(self, size: int | None = ..., /) -> bytes: ...
+    def read1(self, size: int = ..., /) -> bytes: ...
 
 class FileIO(RawIOBase, _RawIOBase, BinaryIO):  # type: ignore[misc]  # incompatible definitions of writelines in the base classes
     mode: str
@@ -69,15 +69,13 @@ class FileIO(RawIOBase, _RawIOBase, BinaryIO):  # type: ignore[misc]  # incompat
     # "name" is a str. In the future, making FileIO generic might help.
     name: Any
     def __init__(
-        self, file: FileDescriptorOrPath, mode: str = "r", closefd: bool = True, opener: _Opener | None = None
+        self, file: FileDescriptorOrPath, mode: str = ..., closefd: bool = ..., opener: _Opener | None = ...
     ) -> None: ...
     @property
     def closefd(self) -> bool: ...
-    def seek(self, pos: int, whence: int = 0, /) -> int: ...
-    def read(self, size: int | None = -1, /) -> bytes | MaybeNone: ...
 
 class BytesIO(BufferedIOBase, _BufferedIOBase, BinaryIO):  # type: ignore[misc]  # incompatible definitions of methods in the base classes
-    def __init__(self, initial_bytes: ReadableBuffer = b"") -> None: ...
+    def __init__(self, initial_bytes: ReadableBuffer = ...) -> None: ...
     # BytesIO does not contain a "name" field. This workaround is necessary
     # to allow BytesIO sub-classes to add this field, as it is defined
     # as a read-only property on IO[].
@@ -85,22 +83,16 @@ class BytesIO(BufferedIOBase, _BufferedIOBase, BinaryIO):  # type: ignore[misc]
     def getvalue(self) -> bytes: ...
     def getbuffer(self) -> memoryview: ...
     def read1(self, size: int | None = -1, /) -> bytes: ...
-    def readlines(self, size: int | None = None, /) -> list[bytes]: ...
-    def seek(self, pos: int, whence: int = 0, /) -> int: ...
 
 class BufferedReader(BufferedIOBase, _BufferedIOBase, BinaryIO):  # type: ignore[misc]  # incompatible definitions of methods in the base classes
     raw: RawIOBase
     def __init__(self, raw: RawIOBase, buffer_size: int = 8192) -> None: ...
     def peek(self, size: int = 0, /) -> bytes: ...
-    def seek(self, target: int, whence: int = 0, /) -> int: ...
-    def truncate(self, pos: int | None = None, /) -> int: ...
 
 class BufferedWriter(BufferedIOBase, _BufferedIOBase, BinaryIO):  # type: ignore[misc]  # incompatible definitions of writelines in the base classes
     raw: RawIOBase
     def __init__(self, raw: RawIOBase, buffer_size: int = 8192) -> None: ...
     def write(self, buffer: ReadableBuffer, /) -> int: ...
-    def seek(self, target: int, whence: int = 0, /) -> int: ...
-    def truncate(self, pos: int | None = None, /) -> int: ...
 
 class BufferedRandom(BufferedIOBase, _BufferedIOBase, BinaryIO):  # type: ignore[misc]  # incompatible definitions of methods in the base classes
     mode: str
@@ -109,11 +101,10 @@ class BufferedRandom(BufferedIOBase, _BufferedIOBase, BinaryIO):  # type: ignore
     def __init__(self, raw: RawIOBase, buffer_size: int = 8192) -> None: ...
     def seek(self, target: int, whence: int = 0, /) -> int: ...  # stubtest needs this
     def peek(self, size: int = 0, /) -> bytes: ...
-    def truncate(self, pos: int | None = None, /) -> int: ...
 
 class BufferedRWPair(BufferedIOBase, _BufferedIOBase):
     def __init__(self, reader: RawIOBase, writer: RawIOBase, buffer_size: int = 8192) -> None: ...
-    def peek(self, size: int = 0, /) -> bytes: ...
+    def peek(self, size: int = ..., /) -> bytes: ...
 
 class _TextIOBase(_IOBase):
     encoding: str
@@ -124,9 +115,9 @@ class _TextIOBase(_IOBase):
     def detach(self) -> BinaryIO: ...
     def write(self, s: str, /) -> int: ...
     def writelines(self, lines: Iterable[str], /) -> None: ...  # type: ignore[override]
-    def readline(self, size: int = -1, /) -> str: ...  # type: ignore[override]
+    def readline(self, size: int = ..., /) -> str: ...  # type: ignore[override]
     def readlines(self, hint: int = -1, /) -> list[str]: ...  # type: ignore[override]
-    def read(self, size: int | None = -1, /) -> str: ...
+    def read(self, size: int | None = ..., /) -> str: ...
 
 @type_check_only
 class _WrappedBuffer(Protocol):
@@ -186,10 +177,9 @@ class TextIOWrapper(TextIOBase, _TextIOBase, TextIO, Generic[_BufferT_co]):  # t
     # TextIOWrapper's version of seek only supports a limited subset of
     # operations.
     def seek(self, cookie: int, whence: int = 0, /) -> int: ...
-    def truncate(self, pos: int | None = None, /) -> int: ...
 
 class StringIO(TextIOBase, _TextIOBase, TextIO):  # type: ignore[misc]  # incompatible definitions of write in the base classes
-    def __init__(self, initial_value: str | None = "", newline: str | None = "\n") -> None: ...
+    def __init__(self, initial_value: str | None = ..., newline: str | None = ...) -> None: ...
     # StringIO does not contain a "name" field. This workaround is necessary
     # to allow StringIO sub-classes to add this field, as it is defined
     # as a read-only property on IO[].
@@ -197,11 +187,9 @@ class StringIO(TextIOBase, _TextIOBase, TextIO):  # type: ignore[misc]  # incomp
     def getvalue(self) -> str: ...
     @property
     def line_buffering(self) -> bool: ...
-    def seek(self, pos: int, whence: int = 0, /) -> int: ...
-    def truncate(self, pos: int | None = None, /) -> int: ...
 
 class IncrementalNewlineDecoder:
-    def __init__(self, decoder: codecs.IncrementalDecoder | None, translate: bool, errors: str = "strict") -> None: ...
+    def __init__(self, decoder: codecs.IncrementalDecoder | None, translate: bool, errors: str = ...) -> None: ...
     def decode(self, input: ReadableBuffer | str, final: bool = False) -> str: ...
     @property
     def newlines(self) -> str | tuple[str, ...] | None: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/_lzma.pyi

@@ -1,60 +0,0 @@
-from _typeshed import ReadableBuffer
-from collections.abc import Mapping, Sequence
-from typing import Any, Final, final
-from typing_extensions import TypeAlias
-
-_FilterChain: TypeAlias = Sequence[Mapping[str, Any]]
-
-FORMAT_AUTO: Final = 0
-FORMAT_XZ: Final = 1
-FORMAT_ALONE: Final = 2
-FORMAT_RAW: Final = 3
-CHECK_NONE: Final = 0
-CHECK_CRC32: Final = 1
-CHECK_CRC64: Final = 4
-CHECK_SHA256: Final = 10
-CHECK_ID_MAX: Final = 15
-CHECK_UNKNOWN: Final = 16
-FILTER_LZMA1: int  # v big number
-FILTER_LZMA2: Final = 33
-FILTER_DELTA: Final = 3
-FILTER_X86: Final = 4
-FILTER_IA64: Final = 6
-FILTER_ARM: Final = 7
-FILTER_ARMTHUMB: Final = 8
-FILTER_SPARC: Final = 9
-FILTER_POWERPC: Final = 5
-MF_HC3: Final = 3
-MF_HC4: Final = 4
-MF_BT2: Final = 18
-MF_BT3: Final = 19
-MF_BT4: Final = 20
-MODE_FAST: Final = 1
-MODE_NORMAL: Final = 2
-PRESET_DEFAULT: Final = 6
-PRESET_EXTREME: int  # v big number
-
-@final
-class LZMADecompressor:
-    def __init__(self, format: int | None = ..., memlimit: int | None = ..., filters: _FilterChain | None = ...) -> None: ...
-    def decompress(self, data: ReadableBuffer, max_length: int = -1) -> bytes: ...
-    @property
-    def check(self) -> int: ...
-    @property
-    def eof(self) -> bool: ...
-    @property
-    def unused_data(self) -> bytes: ...
-    @property
-    def needs_input(self) -> bool: ...
-
-@final
-class LZMACompressor:
-    def __init__(
-        self, format: int | None = ..., check: int = ..., preset: int | None = ..., filters: _FilterChain | None = ...
-    ) -> None: ...
-    def compress(self, data: ReadableBuffer, /) -> bytes: ...
-    def flush(self) -> bytes: ...
-
-class LZMAError(Exception): ...
-
-def is_check_supported(check_id: int, /) -> bool: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/_queue.pyi

@@ -1,20 +0,0 @@
-import sys
-from typing import Any, Generic, TypeVar
-
-if sys.version_info >= (3, 9):
-    from types import GenericAlias
-
-_T = TypeVar("_T")
-
-class Empty(Exception): ...
-
-class SimpleQueue(Generic[_T]):
-    def __init__(self) -> None: ...
-    def empty(self) -> bool: ...
-    def get(self, block: bool = True, timeout: float | None = None) -> _T: ...
-    def get_nowait(self) -> _T: ...
-    def put(self, item: _T, block: bool = True, timeout: float | None = None) -> None: ...
-    def put_nowait(self, item: _T) -> None: ...
-    def qsize(self) -> int: ...
-    if sys.version_info >= (3, 9):
-        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/_struct.pyi

@@ -1,22 +0,0 @@
-from _typeshed import ReadableBuffer, WriteableBuffer
-from collections.abc import Iterator
-from typing import Any
-
-def pack(fmt: str | bytes, /, *v: Any) -> bytes: ...
-def pack_into(fmt: str | bytes, buffer: WriteableBuffer, offset: int, /, *v: Any) -> None: ...
-def unpack(format: str | bytes, buffer: ReadableBuffer, /) -> tuple[Any, ...]: ...
-def unpack_from(format: str | bytes, /, buffer: ReadableBuffer, offset: int = 0) -> tuple[Any, ...]: ...
-def iter_unpack(format: str | bytes, buffer: ReadableBuffer, /) -> Iterator[tuple[Any, ...]]: ...
-def calcsize(format: str | bytes, /) -> int: ...
-
-class Struct:
-    @property
-    def format(self) -> str: ...
-    @property
-    def size(self) -> int: ...
-    def __init__(self, format: str | bytes) -> None: ...
-    def pack(self, *v: Any) -> bytes: ...
-    def pack_into(self, buffer: WriteableBuffer, offset: int, *v: Any) -> None: ...
-    def unpack(self, buffer: ReadableBuffer, /) -> tuple[Any, ...]: ...
-    def unpack_from(self, buffer: ReadableBuffer, offset: int = 0) -> tuple[Any, ...]: ...
-    def iter_unpack(self, buffer: ReadableBuffer, /) -> Iterator[tuple[Any, ...]]: ...

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

@@ -1,5 +1,5 @@
 from typing import Any
-from typing_extensions import Self, TypeAlias
+from typing_extensions import TypeAlias
 from weakref import ReferenceType
 
 __all__ = ["local"]
@@ -12,7 +12,6 @@ class _localimpl:
     def create_dict(self) -> _LocalDict: ...
 
 class local:
-    def __new__(cls, /, *args: Any, **kw: Any) -> Self: ...
     def __getattribute__(self, name: str) -> Any: ...
     def __setattr__(self, name: str, value: Any) -> None: ...
     def __delattr__(self, name: str) -> None: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/builtins.pyi

@@ -1284,7 +1284,9 @@ class property:
 
 @final
 class _NotImplementedType(Any):
-    __call__: None
+    # A little weird, but typing the __call__ as NotImplemented makes the error message
+    # for NotImplemented() much better
+    __call__: NotImplemented  # type: ignore[valid-type]  # pyright: ignore[reportInvalidTypeForm]
 
 NotImplemented: _NotImplementedType
 
@@ -1915,7 +1917,7 @@ class StopIteration(Exception):
 
 class OSError(Exception):
     errno: int | None
-    strerror: str | None
+    strerror: str
     # filename, filename2 are actually str | bytes | None
     filename: Any
     filename2: Any

crates/red_knot_vendored/vendor/typeshed/stdlib/bz2.pyi

@@ -1,10 +1,9 @@
 import _compression
 import sys
-from _bz2 import BZ2Compressor as BZ2Compressor, BZ2Decompressor as BZ2Decompressor
 from _compression import BaseStream
 from _typeshed import ReadableBuffer, StrOrBytesPath, WriteableBuffer
 from collections.abc import Iterable
-from typing import IO, Any, Literal, Protocol, SupportsIndex, TextIO, overload
+from typing import IO, Any, Literal, Protocol, SupportsIndex, TextIO, final, overload
 from typing_extensions import Self, TypeAlias
 
 __all__ = ["BZ2File", "BZ2Compressor", "BZ2Decompressor", "open", "compress", "decompress"]
@@ -129,3 +128,19 @@ class BZ2File(BaseStream, IO[bytes]):
     def seek(self, offset: int, whence: int = 0) -> int: ...
     def write(self, data: ReadableBuffer) -> int: ...
     def writelines(self, seq: Iterable[ReadableBuffer]) -> None: ...
+
+@final
+class BZ2Compressor:
+    def __init__(self, compresslevel: int = 9) -> None: ...
+    def compress(self, data: ReadableBuffer, /) -> bytes: ...
+    def flush(self) -> bytes: ...
+
+@final
+class BZ2Decompressor:
+    def decompress(self, data: ReadableBuffer, max_length: int = -1) -> bytes: ...
+    @property
+    def eof(self) -> bool: ...
+    @property
+    def needs_input(self) -> bool: ...
+    @property
+    def unused_data(self) -> bytes: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/contextvars.pyi

@@ -1,3 +1,63 @@
-from _contextvars import Context as Context, ContextVar as ContextVar, Token as Token, copy_context as copy_context
+import sys
+from collections.abc import Callable, Iterator, Mapping
+from typing import Any, ClassVar, Generic, TypeVar, final, overload
+from typing_extensions import ParamSpec
+
+if sys.version_info >= (3, 9):
+    from types import GenericAlias
 
 __all__ = ("Context", "ContextVar", "Token", "copy_context")
+
+_T = TypeVar("_T")
+_D = TypeVar("_D")
+_P = ParamSpec("_P")
+
+@final
+class ContextVar(Generic[_T]):
+    @overload
+    def __init__(self, name: str) -> None: ...
+    @overload
+    def __init__(self, name: str, *, default: _T) -> None: ...
+    def __hash__(self) -> int: ...
+    @property
+    def name(self) -> str: ...
+    @overload
+    def get(self) -> _T: ...
+    @overload
+    def get(self, default: _T, /) -> _T: ...
+    @overload
+    def get(self, default: _D, /) -> _D | _T: ...
+    def set(self, value: _T, /) -> Token[_T]: ...
+    def reset(self, token: Token[_T], /) -> None: ...
+    if sys.version_info >= (3, 9):
+        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
+
+@final
+class Token(Generic[_T]):
+    @property
+    def var(self) -> ContextVar[_T]: ...
+    @property
+    def old_value(self) -> Any: ...  # returns either _T or MISSING, but that's hard to express
+    MISSING: ClassVar[object]
+    if sys.version_info >= (3, 9):
+        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
+
+def copy_context() -> Context: ...
+
+# It doesn't make sense to make this generic, because for most Contexts each ContextVar will have
+# a different value.
+@final
+class Context(Mapping[ContextVar[Any], Any]):
+    def __init__(self) -> None: ...
+    @overload
+    def get(self, key: ContextVar[_T], default: None = None, /) -> _T | None: ...
+    @overload
+    def get(self, key: ContextVar[_T], default: _T, /) -> _T: ...
+    @overload
+    def get(self, key: ContextVar[_T], default: _D, /) -> _T | _D: ...
+    def run(self, callable: Callable[_P, _T], *args: _P.args, **kwargs: _P.kwargs) -> _T: ...
+    def copy(self) -> Context: ...
+    def __getitem__(self, key: ContextVar[_T], /) -> _T: ...
+    def __iter__(self) -> Iterator[ContextVar[Any]]: ...
+    def __len__(self) -> int: ...
+    def __eq__(self, value: object, /) -> bool: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/dbm/gnu.pyi

@@ -1 +1,47 @@
-from _gdbm import *
+import sys
+from _typeshed import ReadOnlyBuffer, StrOrBytesPath
+from types import TracebackType
+from typing import TypeVar, overload
+from typing_extensions import Self, TypeAlias
+
+if sys.platform != "win32":
+    _T = TypeVar("_T")
+    _KeyType: TypeAlias = str | ReadOnlyBuffer
+    _ValueType: TypeAlias = str | ReadOnlyBuffer
+
+    open_flags: str
+
+    class error(OSError): ...
+    # Actual typename gdbm, not exposed by the implementation
+    class _gdbm:
+        def firstkey(self) -> bytes | None: ...
+        def nextkey(self, key: _KeyType) -> bytes | None: ...
+        def reorganize(self) -> None: ...
+        def sync(self) -> None: ...
+        def close(self) -> None: ...
+        if sys.version_info >= (3, 13):
+            def clear(self) -> None: ...
+
+        def __getitem__(self, item: _KeyType) -> bytes: ...
+        def __setitem__(self, key: _KeyType, value: _ValueType) -> None: ...
+        def __delitem__(self, key: _KeyType) -> None: ...
+        def __contains__(self, key: _KeyType) -> bool: ...
+        def __len__(self) -> int: ...
+        def __enter__(self) -> Self: ...
+        def __exit__(
+            self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
+        ) -> None: ...
+        @overload
+        def get(self, k: _KeyType) -> bytes | None: ...
+        @overload
+        def get(self, k: _KeyType, default: _T) -> bytes | _T: ...
+        def keys(self) -> list[bytes]: ...
+        def setdefault(self, k: _KeyType, default: _ValueType = ...) -> bytes: ...
+        # Don't exist at runtime
+        __new__: None  # type: ignore[assignment]
+        __init__: None  # type: ignore[assignment]
+
+    if sys.version_info >= (3, 11):
+        def open(filename: StrOrBytesPath, flags: str = "r", mode: int = 0o666, /) -> _gdbm: ...
+    else:
+        def open(filename: str, flags: str = "r", mode: int = 0o666, /) -> _gdbm: ...