Bump version to 0.7.4 (#14358)

Fix: #13934 

## Summary

Current implementation has a bug when the current annotation contains a
string with single and double quotes.

TL;DR: I think these cases happen less than other use cases of Literal.
So instead of fixing them we skip the fix in those cases.

One of the problematic cases:

```
from typing import Literal
from third_party import Type

def error(self, type1: Type[Literal["'"]]):
    pass
```

The outcome is:

```
- def error(self, type1: Type[Literal["'"]]):
+ def error(self, type1: "Type[Literal[''']]"):
```

While it should be:

```
"Type[Literal['\'']"
```

The solution in this case is that we check if there’s any quotes same as
the quote style we want to use for this Literal parameter then escape
that same quote used in the string.

Also this case is not uncommon to have:
<https://grep.app/search?current=2&q=Literal["'>

But this can get more complicated for example in case of:

```
- def error(self, type1: Type[Literal["\'"]]):
+ def error(self, type1: "Type[Literal[''']]"):
```

Here we escaped the inner quote but in the generated annotation it gets
removed. Then we flip the quote style of the Literal paramter and the
formatting is wrong.

In this case the solution is more complicated.
1. When generating the string of the source code preserve the backslash.
2. After we have the annotation check if there isn’t any escaped quote
of the same type we want to use for the Literal parameter. In this case
check if we have any `’` without `\` before them. This can get more
complicated since there can be multiple backslashes so checking for only
`\’` won’t be enough.

Another problem is when the string contains `\n`. In case of
`Type[Literal["\n"]]` we generate `'Type[Literal["\n"]]'` and both
pyright and mypy reject this annotation.

https://pyright-play.net/?code=GYJw9gtgBALgngBwJYDsDmUkQWEMoAySMApiAIYA2AUAMaXkDOjUAKoiQNqsC6AXFAB0w6tQAmJYLBKMYAfQCOAVzCk5tMChjlUjOQCNytANaMGjABYAKRiUrAANLA4BGAQHJ2CLkVIVKnABEADoogTw87gCUfNRQ8VAITIyiElKksooqahpaOih6hiZmTNa29k7w3m5sHJy%2BZFRBoeE8MXEJScxAA

## Test Plan

I added test cases for the original code in the reported issue and two
more cases for backslash and new line.

---------

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

.github/workflows/ci.yaml

@@ -16,7 +16,7 @@ env:
   CARGO_TERM_COLOR: always
   RUSTUP_MAX_RETRIES: 10
   PACKAGE_NAME: ruff
-  PYTHON_VERSION: "3.11"
+  PYTHON_VERSION: "3.12"
 
 jobs:
   determine_changes:

.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@v3.11.0
+        uses: cloudflare/wrangler-action@v3.12.1
         with:
           apiToken: ${{ secrets.CF_API_TOKEN }}
           accountId: ${{ secrets.CF_ACCOUNT_ID }}

.pre-commit-config.yaml

@@ -51,11 +51,15 @@ repos:
       - id: blacken-docs
         args: ["--pyi", "--line-length", "130"]
         files: '^crates/.*/resources/mdtest/.*\.md'
+        exclude: |
+          (?x)^(
+            .*?invalid(_.+)*_syntax\.md
+          )$
         additional_dependencies:
           - black==24.10.0
 
   - repo: https://github.com/crate-ci/typos
-    rev: v1.27.0
+    rev: v1.27.3
     hooks:
       - id: typos
 
@@ -69,7 +73,7 @@ repos:
         pass_filenames: false # This makes it a lot faster
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.7.2
+    rev: v0.7.3
     hooks:
       - id: ruff-format
       - id: ruff

CHANGELOG.md

@@ -1,5 +1,91 @@
 # 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

@@ -2,12 +2,6 @@
 # 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"
@@ -123,9 +117,9 @@ dependencies = [
 
 [[package]]
 name = "anyhow"
-version = "1.0.92"
+version = "1.0.93"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "74f37166d7d48a0284b99dd824694c26119c700b53bf0d1540cdb147dbdaaf13"
+checksum = "4c95c10ba0b00a02636238b814946408b1322d5ac4760326e6fb8ec956d85775"
 
 [[package]]
 name = "append-only-vec"
@@ -424,7 +418,7 @@ checksum = "2f8c93eb5f77c9050c7750e14f13ef1033a40a0aac70c6371535b6763a01438c"
 dependencies = [
  "nix 0.28.0",
  "terminfo",
- "thiserror",
+ "thiserror 1.0.67",
  "which",
  "winapi",
 ]
@@ -812,6 +806,17 @@ 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"
@@ -1045,9 +1050,9 @@ dependencies = [
 
 [[package]]
 name = "hashbrown"
-version = "0.15.0"
+version = "0.15.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e087f84d4f86bf4b218b927129862374b72199ae7d8657835f1e89000eea4fb"
+checksum = "3a9bfc1af68b1726ea47d3d5109de126281def866b33970e10fbab11b5dafab3"
 
 [[package]]
 name = "hashlink"
@@ -1108,6 +1113,124 @@ 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"
@@ -1116,12 +1239,23 @@ checksum = "b9e0384b61958566e926dc50660321d12159025e767c18e043daf26b70104c39"
 
 [[package]]
 name = "idna"
-version = "0.5.0"
+version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "634d9b1461af396cad843f47fdba5597a4f9e6ddd4bfb6ff5d85028c25cb12f6"
+checksum = "686f825264d630750a544639377bae737628043f20d38bbc029e8f29ea968a7e"
 dependencies = [
- "unicode-bidi",
- "unicode-normalization",
+ "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",
 ]
 
 [[package]]
@@ -1167,7 +1301,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "707907fe3c25f5424cce2cb7e1cbcafee6bdbe735ca90ef77c29e84591e5b9da"
 dependencies = [
  "equivalent",
- "hashbrown 0.15.0",
+ "hashbrown 0.15.1",
  "serde",
 ]
 
@@ -1260,11 +1394,11 @@ dependencies = [
 
 [[package]]
 name = "is-macro"
-version = "0.3.6"
+version = "0.3.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2069faacbe981460232f880d26bf3c7634e322d49053aa48c27e3ae642f728f1"
+checksum = "1d57a3e447e24c22647738e4607f1df1e0ec6f72e16182c4cd199f647cdfb0e4"
 dependencies = [
- "Inflector",
+ "heck",
  "proc-macro2",
  "quote",
  "syn 2.0.87",
@@ -1367,9 +1501,9 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
 [[package]]
 name = "libc"
-version = "0.2.161"
+version = "0.2.162"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8e9489c2807c139ffd9c1794f4af0ebe86a828db53ecdc7fea2111d0fed085d1"
+checksum = "18d287de67fe55fd7e1581fe933d965a5a9477b38e949cfa9f8574ef01506398"
 
 [[package]]
 name = "libcst"
@@ -1383,7 +1517,7 @@ dependencies = [
  "paste",
  "peg",
  "regex",
- "thiserror",
+ "thiserror 1.0.67",
 ]
 
 [[package]]
@@ -1429,6 +1563,12 @@ 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"
@@ -1486,9 +1626,9 @@ checksum = "2532096657941c2fea9c289d370a250971c689d4f143798ff67113ec042024a5"
 
 [[package]]
 name = "matchit"
-version = "0.8.4"
+version = "0.8.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "47e1ffaa40ddd1f3ed91f717a33c8c0ee23fff369e3aa8772b9605cc1d22f4c3"
+checksum = "bd0aa4b8ca861b08d68afc8702af3250776898c1508b278e1da9d01e01d4b45c"
 
 [[package]]
 name = "memchr"
@@ -1815,7 +1955,7 @@ dependencies = [
  "pep440_rs 0.4.0",
  "regex",
  "serde",
- "thiserror",
+ "thiserror 1.0.67",
  "tracing",
  "unicode-width 0.1.13",
  "url",
@@ -1834,7 +1974,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cd53dff83f26735fdc1ca837098ccf133605d794cdae66acfc2bfac3ec809d95"
 dependencies = [
  "memchr",
- "thiserror",
+ "thiserror 1.0.67",
  "ucd-trie",
 ]
 
@@ -2004,7 +2144,7 @@ dependencies = [
  "newtype-uuid",
  "quick-xml",
  "strip-ansi-escapes",
- "thiserror",
+ "thiserror 1.0.67",
  "uuid",
 ]
 
@@ -2111,7 +2251,7 @@ dependencies = [
  "compact_str",
  "countme",
  "dir-test",
- "hashbrown 0.15.0",
+ "hashbrown 0.15.1",
  "indexmap",
  "insta",
  "itertools 0.13.0",
@@ -2133,7 +2273,7 @@ dependencies = [
  "static_assertions",
  "tempfile",
  "test-case",
- "thiserror",
+ "thiserror 2.0.3",
  "tracing",
 ]
 
@@ -2253,7 +2393,7 @@ checksum = "bd283d9651eeda4b2a83a43c1c91b266c40fd76ecd39a50a8c630ae69dc72891"
 dependencies = [
  "getrandom",
  "libredox",
- "thiserror",
+ "thiserror 1.0.67",
 ]
 
 [[package]]
@@ -2317,7 +2457,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.7.2"
+version = "0.7.4"
 dependencies = [
  "anyhow",
  "argfile",
@@ -2364,7 +2504,7 @@ dependencies = [
  "strum",
  "tempfile",
  "test-case",
- "thiserror",
+ "thiserror 2.0.3",
  "tikv-jemallocator",
  "toml",
  "tracing",
@@ -2432,7 +2572,7 @@ dependencies = [
  "salsa",
  "serde",
  "tempfile",
- "thiserror",
+ "thiserror 2.0.3",
  "tracing",
  "tracing-subscriber",
  "tracing-tree",
@@ -2534,7 +2674,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_linter"
-version = "0.7.2"
+version = "0.7.4"
 dependencies = [
  "aho-corasick",
  "annotate-snippets 0.9.2",
@@ -2584,7 +2724,7 @@ dependencies = [
  "strum",
  "strum_macros",
  "test-case",
- "thiserror",
+ "thiserror 2.0.3",
  "toml",
  "typed-arena",
  "unicode-normalization",
@@ -2618,7 +2758,7 @@ dependencies = [
  "serde_json",
  "serde_with",
  "test-case",
- "thiserror",
+ "thiserror 2.0.3",
  "uuid",
 ]
 
@@ -2691,7 +2831,7 @@ dependencies = [
  "similar",
  "smallvec",
  "static_assertions",
- "thiserror",
+ "thiserror 2.0.3",
  "tracing",
 ]
 
@@ -2771,6 +2911,7 @@ dependencies = [
 name = "ruff_python_stdlib"
 version = "0.0.0"
 dependencies = [
+ "bitflags 2.6.0",
  "unicode-ident",
 ]
 
@@ -2823,7 +2964,7 @@ dependencies = [
  "serde",
  "serde_json",
  "shellexpand",
- "thiserror",
+ "thiserror 2.0.3",
  "tracing",
  "tracing-subscriber",
 ]
@@ -2849,7 +2990,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_wasm"
-version = "0.7.2"
+version = "0.7.4"
 dependencies = [
  "console_error_panic_hook",
  "console_log",
@@ -2932,9 +3073,9 @@ checksum = "583034fd73374156e66797ed8e5b0d5690409c9226b22d87cb7f19821c05d152"
 
 [[package]]
 name = "rustix"
-version = "0.38.37"
+version = "0.38.40"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8acb788b847c24f28525660c4d7758620a7210875711f79e7f663cc152726811"
+checksum = "99e4ea3e1cdc4b559b8e5650f9c8e5998e3e5c1343b4eaf034565f32318d63c0"
 dependencies = [
  "bitflags 2.6.0",
  "errno",
@@ -3234,6 +3375,12 @@ 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"
@@ -3324,9 +3471,9 @@ dependencies = [
 
 [[package]]
 name = "tempfile"
-version = "3.13.0"
+version = "3.14.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f0f2c9fc62d0beef6951ccffd757e241266a2c833136efbe35af6cd2567dca5b"
+checksum = "28cce251fcbc87fac86a866eeb0d6c2d536fc16d06f184bb61aeae11aa4cee0c"
 dependencies = [
  "cfg-if",
  "fastrand",
@@ -3403,7 +3550,16 @@ version = "1.0.67"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3b3c6efbfc763e64eb85c11c25320f0737cb7364c4b6336db90aa9ebe27a0bbd"
 dependencies = [
- "thiserror-impl",
+ "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",
 ]
 
 [[package]]
@@ -3417,6 +3573,17 @@ 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"
@@ -3447,6 +3614,16 @@ 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"
@@ -3663,12 +3840,6 @@ 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"
@@ -3748,9 +3919,9 @@ dependencies = [
 
 [[package]]
 name = "url"
-version = "2.5.2"
+version = "2.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "22784dbdf76fdde8af1aeda5622b546b422b6fc585325248a2bf9f5e41e94d6c"
+checksum = "8d157f1b96d14500ffdc1f10ba712e780825526c03d9a49b4d0324b0d9113ada"
 dependencies = [
  "form_urlencoded",
  "idna",
@@ -3758,6 +3929,18 @@ 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"
@@ -4194,6 +4377,18 @@ 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"
@@ -4209,6 +4404,30 @@ 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"
@@ -4229,12 +4448,55 @@ 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

@@ -136,7 +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 = "1.0.58" }
+thiserror = { version = "2.0.0" }
 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/0.7.2/install.sh | sh
-powershell -c "irm https://astral.sh/ruff/0.7.2/install.ps1 | iex"
+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"
 ```
 
 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: v0.7.2
+  rev: v0.7.4
   hooks:
     # Run the linter.
     - id: ruff

crates/red_knot/src/main.rs

@@ -5,8 +5,6 @@ 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;
@@ -14,7 +12,9 @@ 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};
@@ -318,8 +318,9 @@ impl MainLoop {
                 } => {
                     let has_diagnostics = !result.is_empty();
                     if check_revision == revision {
+                        #[allow(clippy::print_stdout)]
                         for diagnostic in result {
-                            tracing::error!("{}", diagnostic);
+                            println!("{}", diagnostic.display(db));
                         }
                     } else {
                         tracing::debug!(
@@ -378,7 +379,10 @@ impl MainLoopCancellationToken {
 #[derive(Debug)]
 enum MainLoopMessage {
     CheckWorkspace,
-    CheckCompleted { result: Vec<String>, revision: u64 },
+    CheckCompleted {
+        result: Vec<Box<dyn Diagnostic>>,
+        revision: u64,
+    },
     ApplyChanges(Vec<watch::ChangeEvent>),
     Exit,
 }

crates/red_knot_python_semantic/Cargo.toml

@@ -14,6 +14,7 @@ license = { workspace = true }
 ruff_db = { workspace = true }
 ruff_index = { workspace = true }
 ruff_python_ast = { workspace = true, features = ["salsa"] }
+ruff_python_parser = { workspace = true }
 ruff_python_stdlib = { workspace = true }
 ruff_source_file = { workspace = true }
 ruff_text_size = { workspace = true }

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

@@ -0,0 +1,191 @@
+# 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

@@ -1,9 +0,0 @@
-# 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

@@ -110,3 +110,29 @@ 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

@@ -35,6 +35,7 @@ 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

@@ -9,14 +9,21 @@ def bool_instance() -> bool:
 flag = bool_instance()
 
 if flag:
-    class C:
+    class C1:
         x = 1
 
 else:
-    class C:
+    class C1:
         x = 2
 
-reveal_type(C.x)  # revealed: Literal[1, 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]
 ```
 
 ## Inherited attributes
@@ -53,3 +60,77 @@ 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

@@ -18,3 +18,58 @@ 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

@@ -19,6 +19,15 @@ 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
@@ -44,3 +53,16 @@ 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

@@ -0,0 +1,155 @@
+# 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

@@ -41,11 +41,10 @@ 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]],  # error: [call-possibly-unbound-method]
-    z: tuple[type[BaseException], ...],  # error: [call-possibly-unbound-method]
+    y: tuple[type[OSError], type[RuntimeError]],
+    z: tuple[type[BaseException], ...],
 ):
     try:
         help()

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

@@ -0,0 +1,13 @@
+# Exception Handling
+
+## Invalid syntax
+
+```py
+from typing_extensions import reveal_type
+
+try:
+    print
+except as e:  # error: [invalid-syntax]
+    reveal_type(e)  # revealed: Unknown
+
+```

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

@@ -0,0 +1,28 @@
+# 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

@@ -6,13 +6,9 @@ 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
 
@@ -31,17 +27,12 @@ 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 or the use of type param
-# error: [unresolved-reference] "Name `T` used when not defined"
+# TODO not error on the subscripting
 # error: [non-subscriptable]
 class MySecureBox[T](MyBox[T]): ...
 
@@ -66,3 +57,55 @@ 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

@@ -21,6 +21,7 @@ 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]
@@ -50,6 +51,7 @@ 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/loops/for.md

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

crates/red_knot_python_semantic/resources/mdtest/metaclass.md

@@ -0,0 +1,196 @@
+## Default
+
+```py
+class M(type): ...
+
+reveal_type(M.__class__)  # revealed: Literal[type]
+```
+
+## `object`
+
+```py
+reveal_type(object.__class__)  # revealed: Literal[type]
+```
+
+## `type`
+
+```py
+reveal_type(type.__class__)  # revealed: Literal[type]
+```
+
+## Basic
+
+```py
+class M(type): ...
+class B(metaclass=M): ...
+
+reveal_type(B.__class__)  # revealed: Literal[M]
+```
+
+## Invalid metaclass
+
+A class which doesn't inherit `type` (and/or doesn't implement a custom `__new__` accepting the same
+arguments as `type.__new__`) isn't a valid metaclass.
+
+```py
+class M: ...
+class A(metaclass=M): ...
+
+# TODO: emit a diagnostic for the invalid metaclass
+reveal_type(A.__class__)  # revealed: Literal[M]
+```
+
+## Linear inheritance
+
+If a class is a subclass of a class with a custom metaclass, then the subclass will also have that
+metaclass.
+
+```py
+class M(type): ...
+class A(metaclass=M): ...
+class B(A): ...
+
+reveal_type(B.__class__)  # revealed: Literal[M]
+```
+
+## Conflict (1)
+
+The metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its
+bases. ("Strict subclass" is a synonym for "proper subclass"; a non-strict subclass can be a
+subclass or the class itself.)
+
+```py
+class M1(type): ...
+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"
+class C(A, B): ...
+
+reveal_type(C.__class__)  # revealed: Unknown
+```
+
+## Conflict (2)
+
+The metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its
+bases. ("Strict subclass" is a synonym for "proper subclass"; a non-strict subclass can be a
+subclass or the class itself.)
+
+```py
+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"
+class B(A, metaclass=M2): ...
+
+reveal_type(B.__class__)  # revealed: Unknown
+```
+
+## Common metaclass
+
+A class has two explicit bases, both of which have the same metaclass.
+
+```py
+class M(type): ...
+class A(metaclass=M): ...
+class B(metaclass=M): ...
+class C(A, B): ...
+
+reveal_type(C.__class__)  # revealed: Literal[M]
+```
+
+## Metaclass metaclass
+
+A class has an explicit base with a custom metaclass. That metaclass itself has a custom metaclass.
+
+```py
+class M1(type): ...
+class M2(type, metaclass=M1): ...
+class M3(M2): ...
+class A(metaclass=M3): ...
+class B(A): ...
+
+reveal_type(A.__class__)  # revealed: Literal[M3]
+```
+
+## Diamond inheritance
+
+```py
+class M(type): ...
+class M1(M): ...
+class M2(M): ...
+class M12(M1, M2): ...
+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"
+class D(A, B, C): ...
+
+reveal_type(D.__class__)  # revealed: Unknown
+```
+
+## Unknown
+
+```py
+from nonexistent_module import UnknownClass  # error: [unresolved-import]
+
+class C(UnknownClass): ...
+
+# TODO: should be `type[type] & Unknown`
+reveal_type(C.__class__)  # revealed: Literal[type]
+
+class M(type): ...
+class A(metaclass=M): ...
+class B(A, UnknownClass): ...
+
+# TODO: should be `type[M] & Unknown`
+reveal_type(B.__class__)  # revealed: Literal[M]
+```
+
+## Duplicate
+
+```py
+class M(type): ...
+class A(metaclass=M): ...
+class B(A, A): ...  # error: [duplicate-base] "Duplicate base class `A`"
+
+reveal_type(B.__class__)  # revealed: Literal[M]
+```
+
+## Non-class
+
+When a class has an explicit `metaclass` that is not a class, but is a callable that accepts
+`type.__new__` arguments, we should return the meta type of its return type.
+
+```py
+def f(*args, **kwargs) -> int: ...
+
+class A(metaclass=f): ...
+
+# TODO should be `type[int]`
+reveal_type(A.__class__)  # revealed: @Todo
+```
+
+## Cyclic
+
+Retrieving the metaclass of a cyclically defined class should not cause an infinite loop.
+
+```py path=a.pyi
+class A(B): ...  # error: [cyclic-class-def]
+class B(C): ...  # error: [cyclic-class-def]
+class C(A): ...  # error: [cyclic-class-def]
+
+reveal_type(A.__class__)  # revealed: Unknown
+```
+
+## PEP 695 generic
+
+```py
+class M(type): ...
+class A[T: str](metaclass=M): ...
+
+reveal_type(A.__class__)  # revealed: Literal[M]
+```

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

@@ -0,0 +1,247 @@
+# 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/regression/14334_diagnostics_in_wrong_file.md

@@ -0,0 +1,13 @@
+# 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

@@ -60,8 +60,7 @@ reveal_type(typing.__init__)  # revealed: Literal[__init__]
 # These come from `builtins.object`, not `types.ModuleType`:
 reveal_type(typing.__eq__)  # revealed: Literal[__eq__]
 
-# TODO: understand properties
-reveal_type(typing.__class__)  # revealed: Literal[__class__]
+reveal_type(typing.__class__)  # revealed: Literal[type]
 
 # TODO: needs support for attribute access on instances, properties and generics;
 # should be `dict[str, Any]`
@@ -75,6 +74,7 @@ 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

@@ -0,0 +1,139 @@
+# `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, 8))  # revealed: Literal[True]
+reveal_type((3, 8) <= sys.version_info)  # revealed: Literal[True]
+
+reveal_type(sys.version_info > (3, 8))  # revealed: Literal[True]
+reveal_type((3, 8) < sys.version_info)  # revealed: Literal[True]
+
+reveal_type(sys.version_info < (3, 8))  # revealed: Literal[False]
+reveal_type((3, 8) > sys.version_info)  # revealed: Literal[False]
+
+reveal_type(sys.version_info <= (3, 8))  # revealed: Literal[False]
+reveal_type((3, 8) >= sys.version_info)  # revealed: Literal[False]
+
+reveal_type(sys.version_info == (3, 8))  # revealed: Literal[False]
+reveal_type((3, 8) == sys.version_info)  # revealed: Literal[False]
+
+reveal_type(sys.version_info != (3, 8))  # revealed: Literal[True]
+reveal_type((3, 8) != 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, 8, 1))  # revealed: bool
+reveal_type(sys.version_info >= (3, 8, 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, 8, 1, "final", 0, 5))  # revealed: bool
+
+# TODO: this should be `Literal[False]`; see #14279
+reveal_type(sys.version_info == (3, 8, 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, 8))  # revealed: Literal[True]
+reveal_type(foo >= (3, 8))  # revealed: Literal[True]
+
+bar = version_info
+reveal_type(bar >= (3, 8))  # 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, 8))  # 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 >= 8)  # revealed: Literal[True]
+reveal_type(sys.version_info.minor >= 9)  # 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] > 8)  # revealed: Literal[False]
+
+# revealed: tuple[Literal[3], Literal[8], int, Literal["alpha", "beta", "candidate", "final"], int]
+reveal_type(sys.version_info[:5])
+
+reveal_type(sys.version_info[:2] >= (3, 8))  # revealed: Literal[True]
+reveal_type(sys.version_info[0:2] >= (3, 9))  # revealed: Literal[False]
+reveal_type(sys.version_info[:3] >= (3, 9, 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/invert_add_usub.md

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

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

@@ -10,8 +10,6 @@ reveal_type(not not None)  # revealed: Literal[False]
 ## Function
 
 ```py
-from typing import reveal_type
-
 def f():
     return 1
 
@@ -115,3 +113,101 @@ 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/resources/mdtest/unpacking.md

@@ -145,13 +145,8 @@ reveal_type(f)  # revealed: Unknown
 
 ### Non-iterable unpacking
 
-TODO: Remove duplicate diagnostics. This is happening because for a sequence-like assignment target,
-multiple definitions are created and the inference engine runs on each of them which results in
-duplicate diagnostics.
-
 ```py
 # error: "Object of type `Literal[1]` is not iterable"
-# error: "Object of type `Literal[1]` is not iterable"
 a, b = 1
 reveal_type(a)  # revealed: Unknown
 reveal_type(b)  # revealed: Unknown

crates/red_knot_python_semantic/src/node_key.rs

@@ -1,14 +1,14 @@
-use ruff_python_ast::{AnyNodeRef, NodeKind};
-use ruff_text_size::{Ranged, TextRange};
+use ruff_python_ast::AnyNodeRef;
 
 /// Compact key for a node for use in a hash map.
 ///
-/// Compares two nodes by their kind and text range.
+/// 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`.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
-pub(super) struct NodeKey {
-    kind: NodeKind,
-    range: TextRange,
-}
+pub(super) struct NodeKey(usize);
 
 impl NodeKey {
     pub(super) fn from_node<'a, N>(node: N) -> Self
@@ -16,9 +16,6 @@ impl NodeKey {
         N: Into<AnyNodeRef<'a>>,
     {
         let node = node.into();
-        NodeKey {
-            kind: node.kind(),
-            range: node.range(),
-        }
+        NodeKey(node.as_ptr().as_ptr() as usize)
     }
 }

crates/red_knot_python_semantic/src/semantic_index/builder.rs

@@ -281,8 +281,12 @@ impl<'db> SemanticIndexBuilder<'db> {
         debug_assert!(popped_assignment.is_some());
     }
 
-    fn current_assignment(&self) -> Option<&CurrentAssignment<'db>> {
-        self.current_assignments.last()
+    fn current_assignment(&self) -> Option<CurrentAssignment<'db>> {
+        self.current_assignments.last().copied()
+    }
+
+    fn current_assignment_mut(&mut self) -> Option<&mut CurrentAssignment<'db>> {
+        self.current_assignments.last_mut()
     }
 
     fn add_pattern_constraint(
@@ -369,6 +373,11 @@ 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),
+                };
             }
         }
 
@@ -627,6 +636,7 @@ where
                         ast::Expr::List(_) | ast::Expr::Tuple(_) => {
                             Some(CurrentAssignment::Assign {
                                 node,
+                                first: true,
                                 unpack: Some(Unpack::new(
                                     self.db,
                                     self.file,
@@ -640,9 +650,11 @@ where
                                 )),
                             })
                         }
-                        ast::Expr::Name(_) => {
-                            Some(CurrentAssignment::Assign { node, unpack: None })
-                        }
+                        ast::Expr::Name(_) => Some(CurrentAssignment::Assign {
+                            node,
+                            unpack: None,
+                            first: false,
+                        }),
                         _ => None,
                     };
 
@@ -664,9 +676,18 @@ where
                 if let Some(value) = &node.value {
                     self.visit_expr(value);
                 }
-                self.push_assignment(node.into());
-                self.visit_expr(&node.target);
-                self.pop_assignment();
+
+                // 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);
+                }
             }
             ast::Stmt::AugAssign(
                 aug_assign @ ast::StmtAugAssign {
@@ -678,9 +699,18 @@ where
             ) => {
                 debug_assert_eq!(&self.current_assignments, &[]);
                 self.visit_expr(value);
-                self.push_assignment(aug_assign.into());
-                self.visit_expr(target);
-                self.pop_assignment();
+
+                // 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);
+                }
             }
             ast::Stmt::If(node) => {
                 self.visit_expr(&node.test);
@@ -987,14 +1017,19 @@ where
                 }
 
                 if is_definition {
-                    match self.current_assignment().copied() {
-                        Some(CurrentAssignment::Assign { node, unpack }) => {
+                    match self.current_assignment() {
+                        Some(CurrentAssignment::Assign {
+                            node,
+                            first,
+                            unpack,
+                        }) => {
                             self.add_definition(
                                 symbol,
                                 AssignmentDefinitionNodeRef {
                                     unpack,
                                     value: &node.value,
                                     name: name_node,
+                                    first,
                                 },
                             );
                         }
@@ -1045,14 +1080,25 @@ where
                     }
                 }
 
+                if let Some(CurrentAssignment::Assign { first, .. }) = self.current_assignment_mut()
+                {
+                    *first = false;
+                }
+
                 walk_expr(self, expr);
             }
             ast::Expr::Named(node) => {
                 // TODO walrus in comprehensions is implicitly nonlocal
                 self.visit_expr(&node.value);
-                self.push_assignment(node.into());
-                self.visit_expr(&node.target);
-                self.pop_assignment();
+
+                // 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);
+                }
             }
             ast::Expr::Lambda(lambda) => {
                 if let Some(parameters) = &lambda.parameters {
@@ -1245,6 +1291,7 @@ where
 enum CurrentAssignment<'a> {
     Assign {
         node: &'a ast::StmtAssign,
+        first: bool,
         unpack: Option<Unpack<'a>>,
     },
     AnnAssign(&'a ast::StmtAnnAssign),

crates/red_knot_python_semantic/src/semantic_index/definition.rs

@@ -92,6 +92,9 @@ 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> {
@@ -130,6 +133,24 @@ 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)
@@ -183,6 +204,7 @@ pub(crate) struct AssignmentDefinitionNodeRef<'a> {
     pub(crate) unpack: Option<Unpack<'a>>,
     pub(crate) value: &'a ast::Expr,
     pub(crate) name: &'a ast::ExprName,
+    pub(crate) first: bool,
 }
 
 #[derive(Copy, Clone, Debug)]
@@ -250,10 +272,12 @@ impl<'db> DefinitionNodeRef<'db> {
                 unpack,
                 value,
                 name,
+                first,
             }) => DefinitionKind::Assignment(AssignmentDefinitionKind {
                 target: TargetKind::from(unpack),
                 value: AstNodeRef::new(parsed.clone(), value),
                 name: AstNodeRef::new(parsed, name),
+                first,
             }),
             DefinitionNodeRef::AnnotatedAssignment(assign) => {
                 DefinitionKind::AnnotatedAssignment(AstNodeRef::new(parsed, assign))
@@ -314,6 +338,15 @@ 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))
+            }
         }
     }
 
@@ -330,6 +363,7 @@ impl<'db> DefinitionNodeRef<'db> {
                 value: _,
                 unpack: _,
                 name,
+                first: _,
             }) => name.into(),
             Self::AnnotatedAssignment(node) => node.into(),
             Self::AugmentedAssignment(node) => node.into(),
@@ -352,6 +386,9 @@ 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(),
         }
     }
 }
@@ -408,6 +445,9 @@ pub enum DefinitionKind<'db> {
     WithItem(WithItemDefinitionKind),
     MatchPattern(MatchPatternDefinitionKind),
     ExceptHandler(ExceptHandlerDefinitionKind),
+    TypeVar(AstNodeRef<ast::TypeParamTypeVar>),
+    ParamSpec(AstNodeRef<ast::TypeParamParamSpec>),
+    TypeVarTuple(AstNodeRef<ast::TypeParamTypeVarTuple>),
 }
 
 impl DefinitionKind<'_> {
@@ -417,7 +457,10 @@ impl DefinitionKind<'_> {
             DefinitionKind::Function(_)
             | DefinitionKind::Class(_)
             | DefinitionKind::Import(_)
-            | DefinitionKind::ImportFrom(_) => DefinitionCategory::DeclarationAndBinding,
+            | DefinitionKind::ImportFrom(_)
+            | DefinitionKind::TypeVar(_)
+            | DefinitionKind::ParamSpec(_)
+            | DefinitionKind::TypeVarTuple(_) => DefinitionCategory::DeclarationAndBinding,
             // a parameter always binds a value, but is only a declaration if annotated
             DefinitionKind::Parameter(parameter) => {
                 if parameter.annotation.is_some() {
@@ -535,10 +578,11 @@ pub struct AssignmentDefinitionKind<'db> {
     target: TargetKind<'db>,
     value: AstNodeRef<ast::Expr>,
     name: AstNodeRef<ast::ExprName>,
+    first: bool,
 }
 
-impl AssignmentDefinitionKind<'_> {
-    pub(crate) fn target(&self) -> TargetKind {
+impl<'db> AssignmentDefinitionKind<'db> {
+    pub(crate) fn target(&self) -> TargetKind<'db> {
         self.target
     }
 
@@ -549,6 +593,10 @@ impl AssignmentDefinitionKind<'_> {
     pub(crate) fn name(&self) -> &ast::ExprName {
         self.name.node()
     }
+
+    pub(crate) fn is_first(&self) -> bool {
+        self.first
+    }
 }
 
 #[derive(Clone, Debug)]
@@ -687,3 +735,21 @@ 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/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::MayBeUnbound
+            Boundness::PossiblyUnbound
         } 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::MayBeUnbound
+            Boundness::PossiblyUnbound
         } else {
             Boundness::Bound
         }

crates/red_knot_python_semantic/src/stdlib.rs

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

@@ -3,10 +3,19 @@ use crate::{
     Db,
 };
 
-#[derive(Debug, Clone, Copy, PartialEq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub(crate) enum Boundness {
     Bound,
-    MayBeUnbound,
+    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,
+        }
+    }
 }
 
 /// The result of a symbol lookup, which can either be a (possibly unbound) type
@@ -17,14 +26,14 @@ pub(crate) enum Boundness {
 /// bound = 1
 ///
 /// if flag:
-///     maybe_unbound = 2
+///     possibly_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),
-/// maybe_unbound:  Symbol::Type(Type::IntLiteral(2), Boundness::MayBeUnbound),
-/// non_existent:   Symbol::Unbound,
+/// bound:             Symbol::Type(Type::IntLiteral(1), Boundness::Bound),
+/// possibly_unbound:  Symbol::Type(Type::IntLiteral(2), Boundness::PossiblyUnbound),
+/// non_existent:      Symbol::Unbound,
 /// ```
 #[derive(Debug, Clone, PartialEq)]
 pub(crate) enum Symbol<'db> {
@@ -37,25 +46,18 @@ impl<'db> Symbol<'db> {
         matches!(self, Symbol::Unbound)
     }
 
-    pub(crate) fn may_be_unbound(&self) -> bool {
+    pub(crate) fn possibly_unbound(&self) -> bool {
         match self {
-            Symbol::Type(_, Boundness::MayBeUnbound) | Symbol::Unbound => true,
+            Symbol::Type(_, Boundness::PossiblyUnbound) | Symbol::Unbound => true,
             Symbol::Type(_, Boundness::Bound) => false,
         }
     }
 
-    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>> {
+    /// 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>> {
         match self {
             Symbol::Type(ty, _) => Some(*ty),
             Symbol::Unbound => None,
@@ -65,28 +67,80 @@ impl<'db> Symbol<'db> {
     #[cfg(test)]
     #[track_caller]
     pub(crate) fn expect_type(self) -> Type<'db> {
-        self.as_type()
+        self.ignore_possibly_unbound()
             .expect("Expected a (possibly unbound) type, not an unbound symbol")
     }
 
     #[must_use]
-    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,
-            ),
+    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(),
+            },
             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

@@ -246,7 +246,7 @@ 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
@@ -317,7 +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.positive.insert(ty);
+                self.add_positive(db, ty);
             }
             // ~Literal[True] & bool = Literal[False]
             Type::BooleanLiteral(bool)
@@ -383,7 +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, StringLiteralType, UnionBuilder};
+    use crate::types::{global_symbol, KnownClass, UnionBuilder};
     use crate::ProgramSettings;
     use ruff_db::files::system_path_to_file;
     use ruff_db::system::{DbWithTestSystem, SystemPathBuf};
@@ -592,6 +592,22 @@ 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();
@@ -759,7 +775,7 @@ mod tests {
             .build();
         assert_eq!(ty, s);
 
-        let literal = Type::StringLiteral(StringLiteralType::new(&db, "a"));
+        let literal = Type::string_literal(&db, "a");
         let expected = IntersectionBuilder::new(&db)
             .add_positive(s)
             .add_negative(literal)
@@ -862,7 +878,7 @@ mod tests {
 
         let ty = IntersectionBuilder::new(&db)
             .add_positive(s)
-            .add_negative(Type::StringLiteral(StringLiteralType::new(&db, "a")))
+            .add_negative(Type::string_literal(&db, "a"))
             .add_negative(t)
             .build();
         assert_eq!(ty, Type::Never);
@@ -896,7 +912,7 @@ mod tests {
         let db = setup_db();
 
         let t_p = KnownClass::Int.to_instance(&db);
-        let t_n = Type::StringLiteral(StringLiteralType::new(&db, "t_n"));
+        let t_n = Type::string_literal(&db, "t_n");
 
         let ty = IntersectionBuilder::new(&db)
             .add_positive(t_p)

crates/red_knot_python_semantic/src/types/diagnostic.rs

@@ -1,14 +1,15 @@
+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)]
+#[derive(Debug, Eq, PartialEq, Clone)]
 pub struct TypeCheckDiagnostic {
     // TODO: Don't use string keys for rules
     pub(super) rule: String,
@@ -31,6 +32,28 @@ 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
@@ -141,6 +164,23 @@ 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

@@ -1,12 +1,15 @@
 //! Display implementations for types.
 
-use std::fmt::{self, Display, Formatter};
+use std::fmt::{self, Display, Formatter, Write};
 
 use ruff_db::display::FormatterJoinExtension;
 use ruff_python_ast::str::Quote;
 use ruff_python_literal::escape::AsciiEscape;
 
-use crate::types::{ClassLiteralType, InstanceType, IntersectionType, KnownClass, Type, UnionType};
+use crate::types::{
+    ClassLiteralType, InstanceType, IntersectionType, KnownClass, StringLiteralType,
+    SubclassOfType, Type, UnionType,
+};
 use crate::Db;
 use rustc_hash::FxHashMap;
 
@@ -64,10 +67,13 @@ 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, .. })
-                if class.is_known(self.db, KnownClass::NoneType) =>
-            {
-                f.write_str("None")
+            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::Todo]`'s display should be explicit that is not a valid display of
             // any other type
@@ -77,18 +83,16 @@ 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::Instance(InstanceType { class, known }) => f.write_str(match known {
-                Some(super::KnownInstance::Literal) => "Literal",
-                _ => 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::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) => {
-                write!(f, r#""{}""#, string.value(self.db).replace('"', r#"\""#))
-            }
+            Type::StringLiteral(string) => string.display(self.db).fmt(f),
             Type::LiteralString => f.write_str("LiteralString"),
             Type::BytesLiteral(bytes) => {
                 let escape =
@@ -323,15 +327,40 @@ 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, BytesLiteralType, SliceLiteralType, StringLiteralType, Type, UnionType,
-    };
+    use crate::types::{global_symbol, SliceLiteralType, StringLiteralType, Type, UnionType};
     use crate::{Program, ProgramSettings, PythonVersion, SearchPathSettings};
 
     fn setup_db() -> TestDb {
@@ -377,12 +406,12 @@ mod tests {
             Type::Unknown,
             Type::IntLiteral(-1),
             global_symbol(&db, mod_file, "A").expect_type(),
-            Type::StringLiteral(StringLiteralType::new(&db, "A")),
-            Type::BytesLiteral(BytesLiteralType::new(&db, [0u8].as_slice())),
-            Type::BytesLiteral(BytesLiteralType::new(&db, [7u8].as_slice())),
+            Type::string_literal(&db, "A"),
+            Type::bytes_literal(&db, &[0u8]),
+            Type::bytes_literal(&db, &[7u8]),
             Type::IntLiteral(0),
             Type::IntLiteral(1),
-            Type::StringLiteral(StringLiteralType::new(&db, "B")),
+            Type::string_literal(&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(),
@@ -448,4 +477,28 @@ 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

@@ -1,11 +1,10 @@
 use std::collections::VecDeque;
 use std::ops::Deref;
 
-use indexmap::IndexSet;
 use itertools::Either;
 use rustc_hash::FxHashSet;
 
-use super::{Class, ClassLiteralType, KnownClass, Type};
+use super::{Class, ClassLiteralType, KnownClass, KnownInstanceType, Type};
 use crate::Db;
 
 /// The inferred method resolution order of a given class.
@@ -26,22 +25,30 @@ 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| {
-            let fallback_mro = Self::from([
-                ClassBase::Class(class),
-                ClassBase::Unknown,
-                ClassBase::object(db),
-            ]);
-            MroError {
-                kind: error_kind,
-                fallback_mro,
-            }
+        Self::of_class_impl(db, class).map_err(|error_kind| MroError {
+            kind: error_kind,
+            fallback_mro: Self::from_error(db, class),
         })
     }
 
+    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
@@ -77,11 +84,6 @@ 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();
@@ -96,10 +98,6 @@ 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![];
 
@@ -282,13 +280,6 @@ 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
@@ -349,7 +340,7 @@ impl<'db> ClassBase<'db> {
     /// Return a `ClassBase` representing the class `builtins.object`
     fn object(db: &'db dyn Db) -> Self {
         KnownClass::Object
-            .to_class(db)
+            .to_class_literal(db)
             .into_class_literal()
             .map_or(Self::Unknown, |ClassLiteralType { class }| {
                 Self::Class(class)
@@ -377,7 +368,12 @@ impl<'db> ClassBase<'db> {
             | Type::LiteralString
             | Type::Tuple(_)
             | Type::SliceLiteral(_)
-            | Type::ModuleLiteral(_) => None,
+            | Type::ModuleLiteral(_)
+            | Type::SubclassOf(_) => None,
+            Type::KnownInstance(known_instance) => match known_instance {
+                KnownInstanceType::Literal => None,
+                KnownInstanceType::TypeVar(_) => None,
+            },
         }
     }
 
@@ -410,7 +406,7 @@ impl<'db> From<ClassBase<'db>> for Type<'db> {
             ClassBase::Any => Type::Any,
             ClassBase::Todo => Type::Todo,
             ClassBase::Unknown => Type::Unknown,
-            ClassBase::Class(class) => Type::ClassLiteral(ClassLiteralType { class }),
+            ClassBase::Class(class) => Type::class_literal(class),
         }
     }
 }
@@ -456,46 +452,3 @@ 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

@@ -5,8 +5,8 @@ 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, KnownFunction,
-    Truthiness, Type, UnionBuilder,
+    infer_expression_types, ClassLiteralType, IntersectionBuilder, KnownClass,
+    KnownConstraintFunction, KnownFunction, Truthiness, Type, UnionBuilder,
 };
 use crate::Db;
 use itertools::Itertools;
@@ -78,24 +78,27 @@ fn all_negative_narrowing_constraints_for_expression<'db>(
     NarrowingConstraintsBuilder::new(db, ConstraintNode::Expression(expression), false).finish()
 }
 
-/// Generate a constraint from the *type* of the second argument of an `isinstance` call.
+/// Generate a constraint from the type of a `classinfo` argument to `isinstance` or `issubclass`.
 ///
-/// 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>(
+/// 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>(
     db: &'db dyn Db,
     classinfo: &Type<'db>,
-) -> Option<Type<'db>> {
+    to_constraint: F,
+) -> Option<Type<'db>>
+where
+    F: Fn(ClassLiteralType<'db>) -> Type<'db> + Copy,
+{
     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_isinstance_constraint(db, element)?);
+                builder = builder.add(generate_classinfo_constraint(db, element, to_constraint)?);
             }
             Some(builder.build())
         }
+        Type::ClassLiteral(class_literal_type) => Some(to_constraint(*class_literal_type)),
         _ => None,
     }
 }
@@ -330,34 +333,49 @@ impl<'db> NarrowingConstraintsBuilder<'db> {
         let scope = self.scope();
         let inference = infer_expression_types(self.db, expression);
 
-        if let Some(func_type) = inference
+        // 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_ast_id(self.db, scope))
             .into_function_literal()
+            .and_then(|f| f.known(self.db))
+            .and_then(KnownFunction::constraint_function)
         {
-            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
+            Some(function) if expr_call.arguments.keywords.is_empty() => {
+                if let [ast::Expr::Name(ast::ExprName { id, .. }), class_info] =
+                    &*expr_call.arguments.args
                 {
                     let symbol = self.symbols().symbol_id_by_name(id).unwrap();
 
-                    let rhs_type = inference.expression_ty(rhs.scoped_ast_id(self.db, scope));
+                    let class_info_ty =
+                        inference.expression_ty(class_info.scoped_ast_id(self.db, scope));
 
-                    // 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);
+                    let to_constraint = match function {
+                        KnownConstraintFunction::IsInstance => {
+                            |class_literal: ClassLiteralType<'db>| {
+                                Type::instance(class_literal.class)
+                            }
                         }
-                        let mut constraints = NarrowingConstraints::default();
-                        constraints.insert(symbol, constraint);
-                        return Some(constraints);
-                    }
+                        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
                 }
             }
+            _ => None,
         }
-        None
     }
 
     fn evaluate_match_pattern_singleton(

crates/red_knot_python_semantic/src/types/signatures.rs

@@ -0,0 +1,480 @@
+#![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

@@ -0,0 +1,77 @@
+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

@@ -6,7 +6,7 @@ use rustc_hash::FxHashMap;
 
 use crate::semantic_index::ast_ids::{HasScopedAstId, ScopedExpressionId};
 use crate::semantic_index::symbol::ScopeId;
-use crate::types::{TupleType, Type, TypeCheckDiagnostics, TypeCheckDiagnosticsBuilder};
+use crate::types::{Type, TypeCheckDiagnostics, TypeCheckDiagnosticsBuilder};
 use crate::Db;
 
 /// Unpacks the value expression type to their respective targets.
@@ -93,11 +93,10 @@ 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(TupleType::new(
+                    let value_ty = Type::tuple(
                         self.db,
-                        vec![Type::LiteralString; string_literal_ty.len(self.db)]
-                            .into_boxed_slice(),
-                    ));
+                        &vec![Type::LiteralString; string_literal_ty.len(self.db)],
+                    );
                     self.unpack(target, value_ty, scope);
                 }
                 _ => {

crates/red_knot_python_semantic/tests/mdtest.rs

@@ -1,7 +1,8 @@
-use dir_test::{dir_test, Fixture};
-use red_knot_test::run;
+use std::ffi::OsStr;
 use std::path::Path;
 
+use dir_test::{dir_test, Fixture};
+
 /// See `crates/red_knot_test/README.md` for documentation on these tests.
 #[dir_test(
     dir: "$CARGO_MANIFEST_DIR/resources/mdtest",
@@ -9,16 +10,16 @@ use std::path::Path;
 )]
 #[allow(clippy::needless_pass_by_value)]
 fn mdtest(fixture: Fixture<&str>) {
-    let path = fixture.path();
+    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 crate_dir = Path::new(env!("CARGO_MANIFEST_DIR"))
-        .join("resources/mdtest")
-        .canonicalize()
+    let long_title = fixture_path
+        .strip_prefix(workspace_root)
+        .unwrap()
+        .to_str()
         .unwrap();
+    let short_title = fixture_path.file_name().and_then(OsStr::to_str).unwrap();
 
-    let relative_path = path
-        .strip_prefix(crate_dir.to_str().unwrap())
-        .unwrap_or(path);
-
-    run(Path::new(path), relative_path);
+    red_knot_test::run(fixture_path, long_title, short_title);
 }

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;
+pub(crate) use range::{RangeExt, ToRangeExt};
 pub(crate) use text_document::DocumentVersion;
 pub use text_document::TextDocument;
 

crates/red_knot_server/src/edit/range.rs

@@ -1,13 +1,32 @@
+use super::notebook;
 use super::PositionEncoding;
-use ruff_source_file::LineIndex;
+use lsp_types as types;
+use ruff_notebook::NotebookIndex;
 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")
 }
@@ -75,6 +94,61 @@ 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);
@@ -96,3 +170,46 @@ 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

@@ -3,15 +3,17 @@ use std::borrow::Cow;
 use lsp_types::request::DocumentDiagnosticRequest;
 use lsp_types::{
     Diagnostic, DiagnosticSeverity, DocumentDiagnosticParams, DocumentDiagnosticReport,
-    DocumentDiagnosticReportResult, FullDocumentDiagnosticReport, Position, Range,
+    DocumentDiagnosticReportResult, FullDocumentDiagnosticReport, NumberOrString, Range,
     RelatedFullDocumentDiagnosticReport, Url,
 };
 
-use red_knot_workspace::db::RootDatabase;
-
+use crate::edit::ToRangeExt;
 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;
 
@@ -64,36 +66,37 @@ fn compute_diagnostics(snapshot: &DocumentSnapshot, db: &RootDatabase) -> Vec<Di
     diagnostics
         .as_slice()
         .iter()
-        .map(|message| to_lsp_diagnostic(message))
+        .map(|message| to_lsp_diagnostic(db, message, snapshot.encoding()))
         .collect()
 }
 
-fn to_lsp_diagnostic(message: &str) -> Diagnostic {
-    let words = message.split(':').collect::<Vec<_>>();
+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());
 
-    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),
+        range.to_range(&source, &index, encoding)
+    } else {
+        Range::default()
+    };
+
+    let severity = match diagnostic.severity() {
+        Severity::Info => DiagnosticSeverity::INFORMATION,
+        Severity::Error => DiagnosticSeverity::ERROR,
     };
 
     Diagnostic {
         range,
-        severity: Some(DiagnosticSeverity::ERROR),
+        severity: Some(severity),
         tags: None,
-        code: None,
+        code: Some(NumberOrString::String(diagnostic.rule().to_string())),
         code_description: None,
         source: Some("red-knot".into()),
-        message: message.to_string(),
+        message: diagnostic.message().into_owned(),
         related_information: None,
         data: None,
     }

crates/red_knot_test/src/diagnostic.rs

@@ -2,8 +2,8 @@
 //!
 //! We don't assume that we will get the diagnostics in source order.
 
+use ruff_db::diagnostic::Diagnostic;
 use ruff_source_file::{LineIndex, OneIndexed};
-use ruff_text_size::Ranged;
 use std::ops::{Deref, Range};
 
 /// All diagnostics for one embedded Python file, sorted and grouped by start line number.
@@ -19,13 +19,17 @@ pub(crate) struct SortedDiagnostics<T> {
 
 impl<T> SortedDiagnostics<T>
 where
-    T: Ranged + Clone,
+    T: Diagnostic,
 {
     pub(crate) fn new(diagnostics: impl IntoIterator<Item = T>, line_index: &LineIndex) -> Self {
         let mut diagnostics: Vec<_> = diagnostics
             .into_iter()
             .map(|diagnostic| DiagnosticWithLine {
-                line_number: line_index.line_index(diagnostic.start()),
+                line_number: diagnostic
+                    .range()
+                    .map_or(OneIndexed::from_zero_indexed(0), |range| {
+                        line_index.line_index(range.start())
+                    }),
                 diagnostic,
             })
             .collect();
@@ -94,7 +98,7 @@ pub(crate) struct LineDiagnosticsIterator<'a, T> {
 
 impl<'a, T> Iterator for LineDiagnosticsIterator<'a, T>
 where
-    T: Ranged + Clone,
+    T: Diagnostic,
 {
     type Item = LineDiagnostics<'a, T>;
 
@@ -110,7 +114,7 @@ where
     }
 }
 
-impl<T> std::iter::FusedIterator for LineDiagnosticsIterator<'_, T> where T: Clone + Ranged {}
+impl<T> std::iter::FusedIterator for LineDiagnosticsIterator<'_, T> where T: Diagnostic {}
 
 /// All diagnostics that start on a single line of source code in one embedded Python file.
 #[derive(Debug)]
@@ -139,11 +143,14 @@ struct DiagnosticWithLine<T> {
 #[cfg(test)]
 mod tests {
     use crate::db::Db;
-    use ruff_db::files::system_path_to_file;
+    use crate::diagnostic::Diagnostic;
+    use ruff_db::diagnostic::Severity;
+    use ruff_db::files::{system_path_to_file, File};
     use ruff_db::source::line_index;
     use ruff_db::system::{DbWithTestSystem, SystemPathBuf};
     use ruff_source_file::OneIndexed;
     use ruff_text_size::{TextRange, TextSize};
+    use std::borrow::Cow;
 
     #[test]
     fn sort_and_group() {
@@ -152,13 +159,18 @@ mod tests {
         let file = system_path_to_file(&db, "/src/test.py").unwrap();
         let lines = line_index(&db, file);
 
-        let ranges = vec![
+        let ranges = [
             TextRange::new(TextSize::new(0), TextSize::new(1)),
             TextRange::new(TextSize::new(5), TextSize::new(10)),
             TextRange::new(TextSize::new(1), TextSize::new(7)),
         ];
 
-        let sorted = super::SortedDiagnostics::new(&ranges, &lines);
+        let diagnostics: Vec<_> = ranges
+            .into_iter()
+            .map(|range| DummyDiagnostic { range, file })
+            .collect();
+
+        let sorted = super::SortedDiagnostics::new(diagnostics, &lines);
         let grouped = sorted.iter_lines().collect::<Vec<_>>();
 
         let [line1, line2] = &grouped[..] else {
@@ -170,4 +182,32 @@ mod tests {
         assert_eq!(line2.line_number, OneIndexed::from_zero_indexed(1));
         assert_eq!(line2.diagnostics.len(), 1);
     }
+
+    #[derive(Debug)]
+    struct DummyDiagnostic {
+        range: TextRange,
+        file: File,
+    }
+
+    impl Diagnostic for DummyDiagnostic {
+        fn rule(&self) -> &str {
+            "dummy"
+        }
+
+        fn message(&self) -> Cow<str> {
+            "dummy".into()
+        }
+
+        fn file(&self) -> File {
+            self.file
+        }
+
+        fn range(&self) -> Option<TextRange> {
+            Some(self.range)
+        }
+
+        fn severity(&self) -> Severity {
+            Severity::Error
+        }
+    }
 }

crates/red_knot_test/src/lib.rs

@@ -1,6 +1,7 @@
 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};
@@ -18,9 +19,9 @@ mod parser;
 ///
 /// Panic on test failure, and print failure details.
 #[allow(clippy::print_stdout)]
-pub fn run(path: &Path, title: &str) {
+pub fn run(path: &Path, long_title: &str, short_title: &str) {
     let source = std::fs::read_to_string(path).unwrap();
-    let suite = match test_parser::parse(title, &source) {
+    let suite = match test_parser::parse(short_title, &source) {
         Ok(suite) => suite,
         Err(err) => {
             panic!("Error parsing `{}`: {err}", path.to_str().unwrap())
@@ -48,8 +49,8 @@ pub fn run(path: &Path, title: &str) {
                     for failure in failures {
                         let absolute_line_number =
                             backtick_line.checked_add(relative_line_number).unwrap();
-                        let line_info = format!("{title}:{absolute_line_number}").cyan();
-                        println!("    {line_info} {failure}");
+                        let line_info = format!("{long_title}:{absolute_line_number}").cyan();
+                        println!("  {line_info} {failure}");
                     }
                 }
             }
@@ -87,16 +88,24 @@ fn run_test(db: &mut db::Db, test: &parser::MarkdownTest) -> Result<(), Failures
         .filter_map(|test_file| {
             let parsed = parsed_module(db, test_file.file);
 
-            // TODO allow testing against code with syntax errors
-            assert!(
-                parsed.errors().is_empty(),
-                "Python syntax errors in {}, {}: {:?}",
-                test.name(),
-                test_file.file.path(db),
-                parsed.errors()
-            );
+            let mut diagnostics: Vec<Box<_>> = parsed
+                .errors()
+                .iter()
+                .cloned()
+                .map(|error| {
+                    let diagnostic: Box<dyn Diagnostic> =
+                        Box::new(ParseDiagnostic::new(test_file.file, error));
+                    diagnostic
+                })
+                .collect();
 
-            match matcher::match_file(db, test_file.file, check_types(db, test_file.file)) {
+            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());
+                diagnostic
+            }));
+
+            match matcher::match_file(db, test_file.file, diagnostics) {
                 Ok(()) => None,
                 Err(line_failures) => Some(FileFailures {
                     backtick_offset: test_file.backtick_offset,

crates/red_knot_test/src/matcher.rs

@@ -1,17 +1,15 @@
-//! Match [`TypeCheckDiagnostic`]s against [`Assertion`]s and produce test failure messages for any
+//! Match [`Diagnostic`]s against [`Assertion`]s and produce test failure messages for any
 //! mismatches.
 use crate::assertion::{Assertion, ErrorAssertion, InlineFileAssertions};
 use crate::db::Db;
 use crate::diagnostic::SortedDiagnostics;
 use colored::Colorize;
-use red_knot_python_semantic::types::TypeCheckDiagnostic;
+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};
-use ruff_text_size::Ranged;
 use std::cmp::Ordering;
 use std::ops::Range;
-use std::sync::Arc;
 
 #[derive(Debug, Default)]
 pub(super) struct FailuresByLine {
@@ -55,7 +53,7 @@ pub(super) fn match_file<T>(
     diagnostics: impl IntoIterator<Item = T>,
 ) -> Result<(), FailuresByLine>
 where
-    T: Diagnostic + Clone,
+    T: Diagnostic,
 {
     // Parse assertions from comments in the file, and get diagnostics from the file; both
     // ordered by line number.
@@ -126,22 +124,6 @@ where
     }
 }
 
-pub(super) trait Diagnostic: Ranged {
-    fn rule(&self) -> &str;
-
-    fn message(&self) -> &str;
-}
-
-impl Diagnostic for Arc<TypeCheckDiagnostic> {
-    fn rule(&self) -> &str {
-        self.as_ref().rule()
-    }
-
-    fn message(&self) -> &str {
-        self.as_ref().message()
-    }
-}
-
 trait Unmatched {
     fn unmatched(&self) -> String;
 }
@@ -253,10 +235,15 @@ impl Matcher {
         }
     }
 
-    fn column<T: Ranged>(&self, ranged: &T) -> OneIndexed {
-        self.line_index
-            .source_location(ranged.start(), &self.source)
-            .column
+    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))
     }
 
     /// Check if `assertion` matches any [`Diagnostic`]s in `unmatched`.
@@ -323,20 +310,21 @@ impl Matcher {
 #[cfg(test)]
 mod tests {
     use super::FailuresByLine;
-    use ruff_db::files::system_path_to_file;
+    use ruff_db::diagnostic::{Diagnostic, Severity};
+    use ruff_db::files::{system_path_to_file, File};
     use ruff_db::system::{DbWithTestSystem, SystemPathBuf};
     use ruff_python_trivia::textwrap::dedent;
     use ruff_source_file::OneIndexed;
-    use ruff_text_size::{Ranged, TextRange};
+    use ruff_text_size::TextRange;
+    use std::borrow::Cow;
 
-    #[derive(Clone, Debug)]
-    struct TestDiagnostic {
+    struct ExpectedDiagnostic {
         rule: &'static str,
         message: &'static str,
         range: TextRange,
     }
 
-    impl TestDiagnostic {
+    impl ExpectedDiagnostic {
         fn new(rule: &'static str, message: &'static str, offset: usize) -> Self {
             let offset: u32 = offset.try_into().unwrap();
             Self {
@@ -345,32 +333,64 @@ 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,
+            }
+        }
     }
 
-    impl super::Diagnostic for TestDiagnostic {
+    #[derive(Debug)]
+    struct TestDiagnostic {
+        rule: &'static str,
+        message: &'static str,
+        range: TextRange,
+        file: File,
+    }
+
+    impl Diagnostic for TestDiagnostic {
         fn rule(&self) -> &str {
             self.rule
         }
 
-        fn message(&self) -> &str {
-            self.message
+        fn message(&self) -> Cow<str> {
+            self.message.into()
+        }
+
+        fn file(&self) -> File {
+            self.file
+        }
+
+        fn range(&self) -> Option<TextRange> {
+            Some(self.range)
+        }
+
+        fn severity(&self) -> Severity {
+            Severity::Error
         }
     }
 
-    impl Ranged for TestDiagnostic {
-        fn range(&self) -> ruff_text_size::TextRange {
-            self.range
-        }
-    }
-
-    fn get_result(source: &str, diagnostics: Vec<TestDiagnostic>) -> Result<(), FailuresByLine> {
+    fn get_result(
+        source: &str,
+        diagnostics: Vec<ExpectedDiagnostic>,
+    ) -> 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)
+        super::match_file(
+            &db,
+            file,
+            diagnostics
+                .into_iter()
+                .map(|diagnostic| diagnostic.into_diagnostic(file)),
+        )
     }
 
     fn assert_fail(result: Result<(), FailuresByLine>, messages: &[(usize, &[&str])]) {
@@ -403,7 +423,7 @@ mod tests {
     fn revealed_match() {
         let result = get_result(
             "x # revealed: Foo",
-            vec![TestDiagnostic::new(
+            vec![ExpectedDiagnostic::new(
                 "revealed-type",
                 "Revealed type is `Foo`",
                 0,
@@ -417,7 +437,7 @@ mod tests {
     fn revealed_wrong_rule() {
         let result = get_result(
             "x # revealed: Foo",
-            vec![TestDiagnostic::new(
+            vec![ExpectedDiagnostic::new(
                 "not-revealed-type",
                 "Revealed type is `Foo`",
                 0,
@@ -440,7 +460,11 @@ mod tests {
     fn revealed_wrong_message() {
         let result = get_result(
             "x # revealed: Foo",
-            vec![TestDiagnostic::new("revealed-type", "Something else", 0)],
+            vec![ExpectedDiagnostic::new(
+                "revealed-type",
+                "Something else",
+                0,
+            )],
         );
 
         assert_fail(
@@ -467,8 +491,8 @@ mod tests {
         let result = get_result(
             "x # revealed: Foo",
             vec![
-                TestDiagnostic::new("revealed-type", "Revealed type is `Foo`", 0),
-                TestDiagnostic::new("undefined-reveal", "Doesn't matter", 0),
+                ExpectedDiagnostic::new("revealed-type", "Revealed type is `Foo`", 0),
+                ExpectedDiagnostic::new("undefined-reveal", "Doesn't matter", 0),
             ],
         );
 
@@ -479,7 +503,11 @@ mod tests {
     fn revealed_match_with_only_undefined() {
         let result = get_result(
             "x # revealed: Foo",
-            vec![TestDiagnostic::new("undefined-reveal", "Doesn't matter", 0)],
+            vec![ExpectedDiagnostic::new(
+                "undefined-reveal",
+                "Doesn't matter",
+                0,
+            )],
         );
 
         assert_fail(result, &[(0, &["unmatched assertion: revealed: Foo"])]);
@@ -490,8 +518,8 @@ mod tests {
         let result = get_result(
             "x # revealed: Foo",
             vec![
-                TestDiagnostic::new("revealed-type", "Revealed type is `Bar`", 0),
-                TestDiagnostic::new("undefined-reveal", "Doesn't matter", 0),
+                ExpectedDiagnostic::new("revealed-type", "Revealed type is `Bar`", 0),
+                ExpectedDiagnostic::new("undefined-reveal", "Doesn't matter", 0),
             ],
         );
 
@@ -512,8 +540,8 @@ mod tests {
         let result = get_result(
             "reveal_type(1)",
             vec![
-                TestDiagnostic::new("undefined-reveal", "undefined reveal message", 0),
-                TestDiagnostic::new("revealed-type", "Revealed type is `Literal[1]`", 12),
+                ExpectedDiagnostic::new("undefined-reveal", "undefined reveal message", 0),
+                ExpectedDiagnostic::new("revealed-type", "Revealed type is `Literal[1]`", 12),
             ],
         );
 
@@ -535,8 +563,8 @@ mod tests {
         let result = get_result(
             "reveal_type(1) # error: [something-else]",
             vec![
-                TestDiagnostic::new("undefined-reveal", "undefined reveal message", 0),
-                TestDiagnostic::new("revealed-type", "Revealed type is `Literal[1]`", 12),
+                ExpectedDiagnostic::new("undefined-reveal", "undefined reveal message", 0),
+                ExpectedDiagnostic::new("revealed-type", "Revealed type is `Literal[1]`", 12),
             ],
         );
 
@@ -565,7 +593,7 @@ mod tests {
     fn error_match_rule() {
         let result = get_result(
             "x # error: [some-rule]",
-            vec![TestDiagnostic::new("some-rule", "Any message", 0)],
+            vec![ExpectedDiagnostic::new("some-rule", "Any message", 0)],
         );
 
         assert_ok(&result);
@@ -575,7 +603,7 @@ mod tests {
     fn error_wrong_rule() {
         let result = get_result(
             "x # error: [some-rule]",
-            vec![TestDiagnostic::new("anything", "Any message", 0)],
+            vec![ExpectedDiagnostic::new("anything", "Any message", 0)],
         );
 
         assert_fail(
@@ -594,7 +622,11 @@ mod tests {
     fn error_match_message() {
         let result = get_result(
             r#"x # error: "contains this""#,
-            vec![TestDiagnostic::new("anything", "message contains this", 0)],
+            vec![ExpectedDiagnostic::new(
+                "anything",
+                "message contains this",
+                0,
+            )],
         );
 
         assert_ok(&result);
@@ -604,7 +636,7 @@ mod tests {
     fn error_wrong_message() {
         let result = get_result(
             r#"x # error: "contains this""#,
-            vec![TestDiagnostic::new("anything", "Any message", 0)],
+            vec![ExpectedDiagnostic::new("anything", "Any message", 0)],
         );
 
         assert_fail(
@@ -623,7 +655,7 @@ mod tests {
     fn error_match_column_and_rule() {
         let result = get_result(
             "x # error: 1 [some-rule]",
-            vec![TestDiagnostic::new("some-rule", "Any message", 0)],
+            vec![ExpectedDiagnostic::new("some-rule", "Any message", 0)],
         );
 
         assert_ok(&result);
@@ -633,7 +665,7 @@ mod tests {
     fn error_wrong_column() {
         let result = get_result(
             "x # error: 2 [rule]",
-            vec![TestDiagnostic::new("rule", "Any message", 0)],
+            vec![ExpectedDiagnostic::new("rule", "Any message", 0)],
         );
 
         assert_fail(
@@ -652,7 +684,11 @@ mod tests {
     fn error_match_column_and_message() {
         let result = get_result(
             r#"x # error: 1 "contains this""#,
-            vec![TestDiagnostic::new("anything", "message contains this", 0)],
+            vec![ExpectedDiagnostic::new(
+                "anything",
+                "message contains this",
+                0,
+            )],
         );
 
         assert_ok(&result);
@@ -662,7 +698,11 @@ mod tests {
     fn error_match_rule_and_message() {
         let result = get_result(
             r#"x # error: [a-rule] "contains this""#,
-            vec![TestDiagnostic::new("a-rule", "message contains this", 0)],
+            vec![ExpectedDiagnostic::new(
+                "a-rule",
+                "message contains this",
+                0,
+            )],
         );
 
         assert_ok(&result);
@@ -672,7 +712,11 @@ mod tests {
     fn error_match_all() {
         let result = get_result(
             r#"x # error: 1 [a-rule] "contains this""#,
-            vec![TestDiagnostic::new("a-rule", "message contains this", 0)],
+            vec![ExpectedDiagnostic::new(
+                "a-rule",
+                "message contains this",
+                0,
+            )],
         );
 
         assert_ok(&result);
@@ -682,7 +726,11 @@ mod tests {
     fn error_match_all_wrong_column() {
         let result = get_result(
             r#"x # error: 2 [some-rule] "contains this""#,
-            vec![TestDiagnostic::new("some-rule", "message contains this", 0)],
+            vec![ExpectedDiagnostic::new(
+                "some-rule",
+                "message contains this",
+                0,
+            )],
         );
 
         assert_fail(
@@ -701,7 +749,7 @@ mod tests {
     fn error_match_all_wrong_rule() {
         let result = get_result(
             r#"x # error: 1 [some-rule] "contains this""#,
-            vec![TestDiagnostic::new(
+            vec![ExpectedDiagnostic::new(
                 "other-rule",
                 "message contains this",
                 0,
@@ -724,7 +772,7 @@ mod tests {
     fn error_match_all_wrong_message() {
         let result = get_result(
             r#"x # error: 1 [some-rule] "contains this""#,
-            vec![TestDiagnostic::new("some-rule", "Any message", 0)],
+            vec![ExpectedDiagnostic::new("some-rule", "Any message", 0)],
         );
 
         assert_fail(
@@ -757,9 +805,9 @@ mod tests {
         let result = get_result(
             &source,
             vec![
-                TestDiagnostic::new("line-two", "msg", two),
-                TestDiagnostic::new("line-three", "msg", three),
-                TestDiagnostic::new("line-five", "msg", five),
+                ExpectedDiagnostic::new("line-two", "msg", two),
+                ExpectedDiagnostic::new("line-three", "msg", three),
+                ExpectedDiagnostic::new("line-five", "msg", five),
             ],
         );
 
@@ -788,8 +836,8 @@ mod tests {
         let result = get_result(
             &source,
             vec![
-                TestDiagnostic::new("line-one", "msg", one),
-                TestDiagnostic::new("line-two", "msg", two),
+                ExpectedDiagnostic::new("line-one", "msg", one),
+                ExpectedDiagnostic::new("line-two", "msg", two),
             ],
         );
 
@@ -809,8 +857,8 @@ mod tests {
         let result = get_result(
             &source,
             vec![
-                TestDiagnostic::new("one-rule", "msg", x),
-                TestDiagnostic::new("other-rule", "msg", x),
+                ExpectedDiagnostic::new("one-rule", "msg", x),
+                ExpectedDiagnostic::new("other-rule", "msg", x),
             ],
         );
 
@@ -830,8 +878,8 @@ mod tests {
         let result = get_result(
             &source,
             vec![
-                TestDiagnostic::new("one-rule", "msg", x),
-                TestDiagnostic::new("one-rule", "msg", x),
+                ExpectedDiagnostic::new("one-rule", "msg", x),
+                ExpectedDiagnostic::new("one-rule", "msg", x),
             ],
         );
 
@@ -851,9 +899,9 @@ mod tests {
         let result = get_result(
             &source,
             vec![
-                TestDiagnostic::new("one-rule", "msg", x),
-                TestDiagnostic::new("other-rule", "msg", x),
-                TestDiagnostic::new("third-rule", "msg", x),
+                ExpectedDiagnostic::new("one-rule", "msg", x),
+                ExpectedDiagnostic::new("other-rule", "msg", x),
+                ExpectedDiagnostic::new("third-rule", "msg", x),
             ],
         );
 
@@ -877,8 +925,8 @@ mod tests {
         let result = get_result(
             &source,
             vec![
-                TestDiagnostic::new("undefined-reveal", "msg", reveal),
-                TestDiagnostic::new("revealed-type", "Revealed type is `Literal[5]`", reveal),
+                ExpectedDiagnostic::new("undefined-reveal", "msg", reveal),
+                ExpectedDiagnostic::new("revealed-type", "Revealed type is `Literal[5]`", reveal),
             ],
         );
 
@@ -891,7 +939,7 @@ mod tests {
         let x = source.find('x').unwrap();
         let result = get_result(
             source,
-            vec![TestDiagnostic::new("some-rule", "some message", x)],
+            vec![ExpectedDiagnostic::new("some-rule", "some message", x)],
         );
 
         assert_fail(
@@ -912,7 +960,7 @@ mod tests {
         let x = source.find('x').unwrap();
         let result = get_result(
             source,
-            vec![TestDiagnostic::new("some-rule", "some message", x)],
+            vec![ExpectedDiagnostic::new("some-rule", "some message", x)],
         );
 
         assert_fail(

crates/red_knot_vendored/vendor/typeshed/source_commit.txt

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

crates/red_knot_vendored/vendor/typeshed/stdlib/VERSIONS

@@ -24,18 +24,22 @@ _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-
@@ -45,6 +49,7 @@ _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-
@@ -52,12 +57,14 @@ _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

@@ -0,0 +1,18 @@
+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

@@ -0,0 +1,61 @@
+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

@@ -0,0 +1,43 @@
+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, module: types.ModuleType) -> importlib.readers.FileReader: ...
+        def get_resource_reader(self, name: str | None = None) -> importlib.readers.FileReader: ...
     else:
-        def get_resource_reader(self, module: types.ModuleType) -> Self | None: ...
+        def get_resource_reader(self, name: str | None = None) -> 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

@@ -0,0 +1,47 @@
+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 = ..., /) -> int: ...
+    def seek(self, offset: int, whence: int = 0, /) -> int: ...
     def seekable(self) -> bool: ...
     def tell(self) -> int: ...
-    def truncate(self, size: int | None = ..., /) -> int: ...
+    def truncate(self, size: int | None = 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 = ..., /) -> bytes: ...
-    def read1(self, size: int = ..., /) -> bytes: ...
+    def read(self, size: int | None = -1, /) -> bytes: ...
+    def read1(self, size: int = -1, /) -> bytes: ...
 
 class FileIO(RawIOBase, _RawIOBase, BinaryIO):  # type: ignore[misc]  # incompatible definitions of writelines in the base classes
     mode: str
@@ -69,13 +69,15 @@ 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 = ..., closefd: bool = ..., opener: _Opener | None = ...
+        self, file: FileDescriptorOrPath, mode: str = "r", closefd: bool = True, opener: _Opener | None = 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 = ...) -> None: ...
+    def __init__(self, initial_bytes: ReadableBuffer = b"") -> 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[].
@@ -83,16 +85,22 @@ 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
@@ -101,10 +109,11 @@ 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 = ..., /) -> bytes: ...
+    def peek(self, size: int = 0, /) -> bytes: ...
 
 class _TextIOBase(_IOBase):
     encoding: str
@@ -115,9 +124,9 @@ 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 = ..., /) -> str: ...  # type: ignore[override]
+    def readline(self, size: int = -1, /) -> str: ...  # type: ignore[override]
     def readlines(self, hint: int = -1, /) -> list[str]: ...  # type: ignore[override]
-    def read(self, size: int | None = ..., /) -> str: ...
+    def read(self, size: int | None = -1, /) -> str: ...
 
 @type_check_only
 class _WrappedBuffer(Protocol):
@@ -177,9 +186,10 @@ 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 = ...) -> None: ...
+    def __init__(self, initial_value: str | None = "", newline: str | None = "\n") -> 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[].
@@ -187,9 +197,11 @@ 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 = ...) -> None: ...
+    def __init__(self, decoder: codecs.IncrementalDecoder | None, translate: bool, errors: str = "strict") -> 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

@@ -0,0 +1,60 @@
+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

@@ -0,0 +1,20 @@
+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

@@ -0,0 +1,22 @@
+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 TypeAlias
+from typing_extensions import Self, TypeAlias
 from weakref import ReferenceType
 
 __all__ = ["local"]
@@ -12,6 +12,7 @@ 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

@@ -1284,9 +1284,7 @@ class property:
 
 @final
 class _NotImplementedType(Any):
-    # 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]
+    __call__: None
 
 NotImplemented: _NotImplementedType
 
@@ -1917,7 +1915,7 @@ class StopIteration(Exception):
 
 class OSError(Exception):
     errno: int | None
-    strerror: str
+    strerror: str | None
     # filename, filename2 are actually str | bytes | None
     filename: Any
     filename2: Any

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

@@ -1,9 +1,10 @@
 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, final, overload
+from typing import IO, Any, Literal, Protocol, SupportsIndex, TextIO, overload
 from typing_extensions import Self, TypeAlias
 
 __all__ = ["BZ2File", "BZ2Compressor", "BZ2Decompressor", "open", "compress", "decompress"]
@@ -128,19 +129,3 @@ 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

@@ -1,63 +1,3 @@
-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
+from _contextvars import Context as Context, ContextVar as ContextVar, Token as Token, copy_context as copy_context
 
 __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

@@ -1,47 +1 @@
-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: ...
+from _gdbm import *

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

@@ -1,43 +1 @@
-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: ...
+from _dbm import *

crates/red_knot_vendored/vendor/typeshed/stdlib/distutils/ccompiler.pyi

@@ -1,5 +1,5 @@
 from _typeshed import BytesPath, StrPath, Unused
-from collections.abc import Callable, Iterable
+from collections.abc import Callable, Iterable, Sequence
 from distutils.file_util import _BytesPathT, _StrPathT
 from typing import Literal, overload
 from typing_extensions import TypeAlias, TypeVarTuple, Unpack
@@ -63,7 +63,7 @@ class CCompiler:
     def set_executables(self, **args: str) -> None: ...
     def compile(
         self,
-        sources: list[str],
+        sources: Sequence[StrPath],
         output_dir: str | None = None,
         macros: list[_Macro] | None = None,
         include_dirs: list[str] | None = None,

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

@@ -2,7 +2,7 @@ import sys
 from collections.abc import Callable
 from decimal import Decimal
 from numbers import Integral, Rational, Real
-from typing import Any, Literal, SupportsIndex, overload
+from typing import Any, Literal, Protocol, SupportsIndex, overload
 from typing_extensions import Self, TypeAlias
 
 _ComparableNum: TypeAlias = int | float | Decimal | Real
@@ -20,11 +20,19 @@ else:
     @overload
     def gcd(a: Integral, b: Integral) -> Integral: ...
 
+class _ConvertibleToIntegerRatio(Protocol):
+    def as_integer_ratio(self) -> tuple[int | Rational, int | Rational]: ...
+
 class Fraction(Rational):
     @overload
     def __new__(cls, numerator: int | Rational = 0, denominator: int | Rational | None = None) -> Self: ...
     @overload
     def __new__(cls, value: float | Decimal | str, /) -> Self: ...
+
+    if sys.version_info >= (3, 14):
+        @overload
+        def __new__(cls, value: _ConvertibleToIntegerRatio) -> Self: ...
+
     @classmethod
     def from_float(cls, f: float) -> Self: ...
     @classmethod

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

@@ -1,7 +1,11 @@
+from collections.abc import Iterable
+
 __all__ = ["GetoptError", "error", "getopt", "gnu_getopt"]
 
-def getopt(args: list[str], shortopts: str, longopts: list[str] = []) -> tuple[list[tuple[str, str]], list[str]]: ...
-def gnu_getopt(args: list[str], shortopts: str, longopts: list[str] = []) -> tuple[list[tuple[str, str]], list[str]]: ...
+def getopt(args: list[str], shortopts: str, longopts: Iterable[str] | str = []) -> tuple[list[tuple[str, str]], list[str]]: ...
+def gnu_getopt(
+    args: list[str], shortopts: str, longopts: Iterable[str] | str = []
+) -> tuple[list[tuple[str, str]], list[str]]: ...
 
 class GetoptError(Exception):
     msg: str

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

@@ -128,19 +128,6 @@ class _BaseNetwork(_IPAddressBase, Generic[_A]):
     @property
     def hostmask(self) -> _A: ...
 
-class _BaseInterface(_BaseAddress, Generic[_A, _N]):
-    hostmask: _A
-    netmask: _A
-    network: _N
-    @property
-    def ip(self) -> _A: ...
-    @property
-    def with_hostmask(self) -> str: ...
-    @property
-    def with_netmask(self) -> str: ...
-    @property
-    def with_prefixlen(self) -> str: ...
-
 class _BaseV4:
     @property
     def version(self) -> Literal[4]: ...
@@ -154,9 +141,21 @@ class IPv4Address(_BaseV4, _BaseAddress):
 
 class IPv4Network(_BaseV4, _BaseNetwork[IPv4Address]): ...
 
-class IPv4Interface(IPv4Address, _BaseInterface[IPv4Address, IPv4Network]):
+class IPv4Interface(IPv4Address):
+    netmask: IPv4Address
+    network: IPv4Network
     def __eq__(self, other: object) -> bool: ...
     def __hash__(self) -> int: ...
+    @property
+    def hostmask(self) -> IPv4Address: ...
+    @property
+    def ip(self) -> IPv4Address: ...
+    @property
+    def with_hostmask(self) -> str: ...
+    @property
+    def with_netmask(self) -> str: ...
+    @property
+    def with_prefixlen(self) -> str: ...
 
 class _BaseV6:
     @property
@@ -184,9 +183,21 @@ class IPv6Network(_BaseV6, _BaseNetwork[IPv6Address]):
     @property
     def is_site_local(self) -> bool: ...
 
-class IPv6Interface(IPv6Address, _BaseInterface[IPv6Address, IPv6Network]):
+class IPv6Interface(IPv6Address):
+    netmask: IPv6Address
+    network: IPv6Network
     def __eq__(self, other: object) -> bool: ...
     def __hash__(self) -> int: ...
+    @property
+    def hostmask(self) -> IPv6Address: ...
+    @property
+    def ip(self) -> IPv6Address: ...
+    @property
+    def with_hostmask(self) -> str: ...
+    @property
+    def with_netmask(self) -> str: ...
+    @property
+    def with_prefixlen(self) -> str: ...
 
 def v4_int_to_packed(address: int) -> bytes: ...
 def v6_int_to_packed(address: int) -> bytes: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/logging/config.pyi

@@ -1,6 +1,6 @@
 import sys
 from _typeshed import StrOrBytesPath
-from collections.abc import Callable, Hashable, Iterable, Sequence
+from collections.abc import Callable, Hashable, Iterable, Mapping, Sequence
 from configparser import RawConfigParser
 from re import Pattern
 from threading import Thread
@@ -63,7 +63,7 @@ def dictConfig(config: _DictConfigArgs | dict[str, Any]) -> None: ...
 if sys.version_info >= (3, 10):
     def fileConfig(
         fname: StrOrBytesPath | IO[str] | RawConfigParser,
-        defaults: dict[str, str] | None = None,
+        defaults: Mapping[str, str] | None = None,
         disable_existing_loggers: bool = True,
         encoding: str | None = None,
     ) -> None: ...
@@ -71,7 +71,7 @@ if sys.version_info >= (3, 10):
 else:
     def fileConfig(
         fname: StrOrBytesPath | IO[str] | RawConfigParser,
-        defaults: dict[str, str] | None = None,
+        defaults: Mapping[str, str] | None = None,
         disable_existing_loggers: bool = True,
     ) -> None: ...
 

crates/red_knot_vendored/vendor/typeshed/stdlib/logging/handlers.pyi

@@ -260,6 +260,8 @@ class QueueHandler(Handler):
     def __init__(self, queue: _QueueLike[Any]) -> None: ...
     def prepare(self, record: LogRecord) -> Any: ...
     def enqueue(self, record: LogRecord) -> None: ...
+    if sys.version_info >= (3, 12):
+        listener: QueueListener | None
 
 class QueueListener:
     handlers: tuple[Handler, ...]  # undocumented

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

@@ -1,7 +1,41 @@
 from _compression import BaseStream
+from _lzma import (
+    CHECK_CRC32 as CHECK_CRC32,
+    CHECK_CRC64 as CHECK_CRC64,
+    CHECK_ID_MAX as CHECK_ID_MAX,
+    CHECK_NONE as CHECK_NONE,
+    CHECK_SHA256 as CHECK_SHA256,
+    CHECK_UNKNOWN as CHECK_UNKNOWN,
+    FILTER_ARM as FILTER_ARM,
+    FILTER_ARMTHUMB as FILTER_ARMTHUMB,
+    FILTER_DELTA as FILTER_DELTA,
+    FILTER_IA64 as FILTER_IA64,
+    FILTER_LZMA1 as FILTER_LZMA1,
+    FILTER_LZMA2 as FILTER_LZMA2,
+    FILTER_POWERPC as FILTER_POWERPC,
+    FILTER_SPARC as FILTER_SPARC,
+    FILTER_X86 as FILTER_X86,
+    FORMAT_ALONE as FORMAT_ALONE,
+    FORMAT_AUTO as FORMAT_AUTO,
+    FORMAT_RAW as FORMAT_RAW,
+    FORMAT_XZ as FORMAT_XZ,
+    MF_BT2 as MF_BT2,
+    MF_BT3 as MF_BT3,
+    MF_BT4 as MF_BT4,
+    MF_HC3 as MF_HC3,
+    MF_HC4 as MF_HC4,
+    MODE_FAST as MODE_FAST,
+    MODE_NORMAL as MODE_NORMAL,
+    PRESET_DEFAULT as PRESET_DEFAULT,
+    PRESET_EXTREME as PRESET_EXTREME,
+    LZMACompressor as LZMACompressor,
+    LZMADecompressor as LZMADecompressor,
+    LZMAError as LZMAError,
+    _FilterChain,
+    is_check_supported as is_check_supported,
+)
 from _typeshed import ReadableBuffer, StrOrBytesPath
-from collections.abc import Mapping, Sequence
-from typing import IO, Any, Final, Literal, TextIO, final, overload
+from typing import IO, Literal, TextIO, overload
 from typing_extensions import Self, TypeAlias
 
 __all__ = [
@@ -48,62 +82,6 @@ _OpenTextWritingMode: TypeAlias = Literal["wt", "xt", "at"]
 
 _PathOrFile: TypeAlias = StrOrBytesPath | IO[bytes]
 
-_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
-
-# from _lzma.c
-@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: ...
-
-# from _lzma.c
-@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): ...
-
 class LZMAFile(BaseStream, IO[bytes]):  # type: ignore[misc]  # incompatible definitions of writelines in the base classes
     def __init__(
         self,
@@ -194,4 +172,3 @@ def compress(
 def decompress(
     data: ReadableBuffer, format: int = 0, memlimit: int | None = None, filters: _FilterChain | None = None
 ) -> bytes: ...
-def is_check_supported(check_id: int, /) -> bool: ...

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

@@ -34,9 +34,22 @@ class mmap:
     if sys.platform == "win32":
         def __init__(self, fileno: int, length: int, tagname: str | None = ..., access: int = ..., offset: int = ...) -> None: ...
     else:
-        def __init__(
-            self, fileno: int, length: int, flags: int = ..., prot: int = ..., access: int = ..., offset: int = ...
-        ) -> None: ...
+        if sys.version_info >= (3, 13):
+            def __init__(
+                self,
+                fileno: int,
+                length: int,
+                flags: int = ...,
+                prot: int = ...,
+                access: int = ...,
+                offset: int = ...,
+                *,
+                trackfd: bool = True,
+            ) -> None: ...
+        else:
+            def __init__(
+                self, fileno: int, length: int, flags: int = ..., prot: int = ..., access: int = ..., offset: int = ...
+            ) -> None: ...
 
     def close(self) -> None: ...
     def flush(self, offset: int = ..., size: int = ...) -> None: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/multiprocessing/managers.pyi

@@ -10,6 +10,7 @@ from typing_extensions import Self, TypeAlias
 from .connection import Connection
 from .context import BaseContext
 from .shared_memory import _SLT, ShareableList as _ShareableList, SharedMemory as _SharedMemory
+from .util import Finalize as _Finalize
 
 __all__ = ["BaseManager", "SyncManager", "BaseProxy", "Token", "SharedMemoryManager"]
 
@@ -60,31 +61,58 @@ class ValueProxy(BaseProxy, Generic[_T]):
     if sys.version_info >= (3, 9):
         def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
 
-class DictProxy(BaseProxy, MutableMapping[_KT, _VT]):
-    __builtins__: ClassVar[dict[str, Any]]
-    def __len__(self) -> int: ...
-    def __getitem__(self, key: _KT, /) -> _VT: ...
-    def __setitem__(self, key: _KT, value: _VT, /) -> None: ...
-    def __delitem__(self, key: _KT, /) -> None: ...
-    def __iter__(self) -> Iterator[_KT]: ...
-    def copy(self) -> dict[_KT, _VT]: ...
-    @overload  # type: ignore[override]
-    def get(self, key: _KT, /) -> _VT | None: ...
-    @overload
-    def get(self, key: _KT, default: _VT, /) -> _VT: ...
-    @overload
-    def get(self, key: _KT, default: _T, /) -> _VT | _T: ...
-    @overload
-    def pop(self, key: _KT, /) -> _VT: ...
-    @overload
-    def pop(self, key: _KT, default: _VT, /) -> _VT: ...
-    @overload
-    def pop(self, key: _KT, default: _T, /) -> _VT | _T: ...
-    def keys(self) -> list[_KT]: ...  # type: ignore[override]
-    def items(self) -> list[tuple[_KT, _VT]]: ...  # type: ignore[override]
-    def values(self) -> list[_VT]: ...  # type: ignore[override]
-    if sys.version_info >= (3, 13):
-        def __class_getitem__(cls, args: Any, /) -> Any: ...
+if sys.version_info >= (3, 13):
+    class _BaseDictProxy(BaseProxy, MutableMapping[_KT, _VT]):
+        __builtins__: ClassVar[dict[str, Any]]
+        def __len__(self) -> int: ...
+        def __getitem__(self, key: _KT, /) -> _VT: ...
+        def __setitem__(self, key: _KT, value: _VT, /) -> None: ...
+        def __delitem__(self, key: _KT, /) -> None: ...
+        def __iter__(self) -> Iterator[_KT]: ...
+        def copy(self) -> dict[_KT, _VT]: ...
+        @overload  # type: ignore[override]
+        def get(self, key: _KT, /) -> _VT | None: ...
+        @overload
+        def get(self, key: _KT, default: _VT, /) -> _VT: ...
+        @overload
+        def get(self, key: _KT, default: _T, /) -> _VT | _T: ...
+        @overload
+        def pop(self, key: _KT, /) -> _VT: ...
+        @overload
+        def pop(self, key: _KT, default: _VT, /) -> _VT: ...
+        @overload
+        def pop(self, key: _KT, default: _T, /) -> _VT | _T: ...
+        def keys(self) -> list[_KT]: ...  # type: ignore[override]
+        def items(self) -> list[tuple[_KT, _VT]]: ...  # type: ignore[override]
+        def values(self) -> list[_VT]: ...  # type: ignore[override]
+
+    class DictProxy(_BaseDictProxy[_KT, _VT]):
+        def __class_getitem__(cls, args: Any, /) -> GenericAlias: ...
+
+else:
+    class DictProxy(BaseProxy, MutableMapping[_KT, _VT]):
+        __builtins__: ClassVar[dict[str, Any]]
+        def __len__(self) -> int: ...
+        def __getitem__(self, key: _KT, /) -> _VT: ...
+        def __setitem__(self, key: _KT, value: _VT, /) -> None: ...
+        def __delitem__(self, key: _KT, /) -> None: ...
+        def __iter__(self) -> Iterator[_KT]: ...
+        def copy(self) -> dict[_KT, _VT]: ...
+        @overload  # type: ignore[override]
+        def get(self, key: _KT, /) -> _VT | None: ...
+        @overload
+        def get(self, key: _KT, default: _VT, /) -> _VT: ...
+        @overload
+        def get(self, key: _KT, default: _T, /) -> _VT | _T: ...
+        @overload
+        def pop(self, key: _KT, /) -> _VT: ...
+        @overload
+        def pop(self, key: _KT, default: _VT, /) -> _VT: ...
+        @overload
+        def pop(self, key: _KT, default: _T, /) -> _VT | _T: ...
+        def keys(self) -> list[_KT]: ...  # type: ignore[override]
+        def items(self) -> list[tuple[_KT, _VT]]: ...  # type: ignore[override]
+        def values(self) -> list[_VT]: ...  # type: ignore[override]
 
 class BaseListProxy(BaseProxy, MutableSequence[_T]):
     __builtins__: ClassVar[dict[str, Any]]
@@ -156,7 +184,7 @@ class BaseManager:
     def get_server(self) -> Server: ...
     def connect(self) -> None: ...
     def start(self, initializer: Callable[..., object] | None = None, initargs: Iterable[Any] = ()) -> None: ...
-    def shutdown(self) -> None: ...  # only available after start() was called
+    shutdown: _Finalize  # only available after start() was called
     def join(self, timeout: float | None = None) -> None: ...  # undocumented
     @property
     def address(self) -> Any: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/multiprocessing/spawn.pyi

@@ -23,7 +23,7 @@ def get_command_line(**kwds: Any) -> list[str]: ...
 def spawn_main(pipe_handle: int, parent_pid: int | None = None, tracker_fd: int | None = None) -> None: ...
 
 # undocumented
-def _main(fd: int) -> Any: ...
+def _main(fd: int, parent_sentinel: int) -> int: ...
 def get_preparation_data(name: str) -> dict[str, Any]: ...
 
 old_main_modules: list[ModuleType]

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

@@ -1,4 +1,5 @@
 import sys
+from _queue import Empty as Empty, SimpleQueue as SimpleQueue
 from threading import Condition, Lock
 from typing import Any, Generic, TypeVar
 
@@ -11,7 +12,6 @@ if sys.version_info >= (3, 13):
 
 _T = TypeVar("_T")
 
-class Empty(Exception): ...
 class Full(Exception): ...
 
 if sys.version_info >= (3, 13):
@@ -55,14 +55,3 @@ class PriorityQueue(Queue[_T]):
 
 class LifoQueue(Queue[_T]):
     queue: list[_T]
-
-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

@@ -1,26 +1,5 @@
-from _typeshed import ReadableBuffer, WriteableBuffer
-from collections.abc import Iterator
-from typing import Any
+from _struct import *
 
 __all__ = ["calcsize", "pack", "pack_into", "unpack", "unpack_from", "iter_unpack", "Struct", "error"]
 
 class error(Exception): ...
-
-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/tarfile.pyi

@@ -1,7 +1,7 @@
 import bz2
 import io
 import sys
-from _typeshed import StrOrBytesPath, StrPath
+from _typeshed import StrOrBytesPath, StrPath, SupportsRead
 from builtins import list as _list  # aliases to avoid name clashes with fields named "type" or "list"
 from collections.abc import Callable, Iterable, Iterator, Mapping
 from gzip import _ReadableFileobj as _GzipReadableFileobj, _WritableFileobj as _GzipWritableFileobj
@@ -481,7 +481,7 @@ class TarFile:
         *,
         filter: Callable[[TarInfo], TarInfo | None] | None = None,
     ) -> None: ...
-    def addfile(self, tarinfo: TarInfo, fileobj: IO[bytes] | None = None) -> None: ...
+    def addfile(self, tarinfo: TarInfo, fileobj: SupportsRead[bytes] | None = None) -> None: ...
     def gettarinfo(
         self, name: StrOrBytesPath | None = None, arcname: str | None = None, fileobj: IO[bytes] | None = None
     ) -> TarInfo: ...

crates/red_knot_wasm/src/lib.rs

@@ -6,6 +6,7 @@ use wasm_bindgen::prelude::*;
 use red_knot_workspace::db::RootDatabase;
 use red_knot_workspace::workspace::settings::Configuration;
 use red_knot_workspace::workspace::WorkspaceMetadata;
+use ruff_db::diagnostic::Diagnostic;
 use ruff_db::files::{system_path_to_file, File};
 use ruff_db::system::walk_directory::WalkDirectoryBuilder;
 use ruff_db::system::{
@@ -110,14 +111,20 @@ impl Workspace {
     pub fn check_file(&self, file_id: &FileHandle) -> Result<Vec<String>, Error> {
         let result = self.db.check_file(file_id.file).map_err(into_error)?;
 
-        Ok(result)
+        Ok(result
+            .into_iter()
+            .map(|diagnostic| diagnostic.display(&self.db).to_string())
+            .collect())
     }
 
     /// Checks all open files
     pub fn check(&self) -> Result<Vec<String>, Error> {
         let result = self.db.check().map_err(into_error)?;
 
-        Ok(result)
+        Ok(result
+            .into_iter()
+            .map(|diagnostic| diagnostic.display(&self.db).to_string())
+            .collect())
     }
 
     /// Returns the parsed AST for `path`

crates/red_knot_wasm/tests/api.rs

@@ -19,6 +19,6 @@ fn check() {
 
     assert_eq!(
         result,
-        vec!["/test.py:1:8: Cannot resolve import `random22`"]
+        vec!["error[unresolved-import] /test.py:1:8 Cannot resolve import `random22`"]
     );
 }

crates/red_knot_workspace/resources/test/corpus/04_assign_invalid_target.py

@@ -0,0 +1 @@
+../../../../ruff_python_parser/resources/invalid/statements/invalid_assignment_targets.py