Switched from mypy to Zuban for static type checking

.github/workflows/test.yml

@@ -51,15 +51,39 @@ jobs:
       uses: actions/setup-python@v6
       with:
         python-version: 3.x
+        cache: pip
+        cache-dependency-path: pyproject.toml
     - uses: actions/cache@v6
       with:
         path: ~/.cache/pip
         key: pip-pyright
     - name: Install dependencies
-      run: pip install -e . pyright
+      run: pip install --group pyright -e .
     - name: Run pyright
       run: pyright --ignoreexternal --verifytypes anyio
 
+  zuban:
+    runs-on: ubuntu-latest
+    needs: changed-files
+    if: |
+      ${{
+        (needs.changed-files.outputs.workflow-changed == 'true')
+        || (needs.changed-files.outputs.src-changed == 'true')
+        || (needs.changed-files.outputs.tests-changed == 'true')
+      }}
+    steps:
+    - uses: actions/checkout@v7
+    - name: Set up Python
+      uses: actions/setup-python@v6
+      with:
+        python-version: 3.x
+        cache: pip
+        cache-dependency-path: pyproject.toml
+    - name: Install dependencies
+      run: pip install --group zuban -e .
+    - name: Run zuban
+      run: zuban check
+
   test:
     strategy:
       fail-fast: false

.pre-commit-config.yaml

@@ -35,15 +35,6 @@ repos:
         args: [--fix, --show-fixes]
       - id: ruff-format
 
-  - repo: https://github.com/pre-commit/mirrors-mypy
-    rev: v2.3.0
-    hooks:
-      - id: mypy
-        pass_filenames: false
-        additional_dependencies:
-          - pytest
-          - trio >= 0.26
-
   - repo: https://github.com/pre-commit/pygrep-hooks
     rev: v1.10.0
     hooks:

pyproject.toml

@@ -74,6 +74,12 @@ doc = [
     "sphinx-autodoc-typehints >= 1.2.0",
     "sphinx-tabs >= 3.3.1",
 ]
+pyright = [
+    "pyright >= 1.1.411",
+]
+zuban = [
+    "zuban >= 0.9.1",
+]
 
 [tool.setuptools_scm]
 version_scheme = "post-release"
@@ -114,12 +120,13 @@ ignore = [
 "tests/test_tempfile.py" = ["ASYNC230"]
 "tests/*.py" = ["ASYNC240"]
 
-[tool.mypy]
+[tool.zuban]
 python_version = "3.14"
 strict = true
+warn_unreachable = false
 disallow_any_generics = false
 warn_return_any = false
-files = ["src", "tests"]
+files = ["src"]
 
 [tool.pytest]
 addopts = [
@@ -187,8 +194,14 @@ depends = []
 allowlist_externals = ["pre-commit"]
 package = "skip"
 
+[tool.tox.env.zuban]
+commands = [["zuban", "check"]]
+dependency_groups = ["zuban"]
+allowlist_externals = ["zuban"]
+package = "skip"
+
 [tool.tox.env.pyright]
-deps = ["pyright"]
+dependency_groups = ["pyright"]
 commands = [["pyright", "--ignoreexternal", "--verifytypes", "anyio"]]
 
 [tool.tox.env.docs]

src/anyio/_backends/_asyncio.py

@@ -1423,6 +1423,7 @@ def callback(f: object) -> None:
             del self._receive_future
             loop.remove_reader(self.__raw_socket)
 
+        f: asyncio.Future[None]
         f = self._receive_future = asyncio.Future()
         loop.add_reader(self.__raw_socket, f.set_result, None)
         f.add_done_callback(callback)
@@ -1433,6 +1434,7 @@ def callback(f: object) -> None:
             del self._send_future
             loop.remove_writer(self.__raw_socket)
 
+        f: asyncio.Future[None]
         f = self._send_future = asyncio.Future()
         loop.add_writer(self.__raw_socket, f.set_result, None)
         f.add_done_callback(callback)
@@ -2583,7 +2585,7 @@ def create_capacity_limiter(cls, total_tokens: float) -> abc.CapacityLimiter:
         return CapacityLimiter(total_tokens)
 
     @classmethod
-    async def run_sync_in_worker_thread(  # type: ignore[return]
+    async def run_sync_in_worker_thread(  # type: ignore[return-value]
         cls,
         func: Callable[[Unpack[PosArgsT]], T_Retval],
         args: tuple[Unpack[PosArgsT]],
@@ -2779,11 +2781,8 @@ def setup_process_pool_exit_at_shutdown(cls, workers: set[abc.Process]) -> None:
     async def connect_tcp(
         cls, host: str, port: int, local_address: IPSockAddrType | None = None
     ) -> abc.SocketStream:
-        transport, protocol = cast(
-            tuple[asyncio.Transport, StreamProtocol],
-            await get_running_loop().create_connection(
-                StreamProtocol, host, port, local_addr=local_address
-            ),
+        transport, protocol = await get_running_loop().create_connection(
+            StreamProtocol, host, port, local_addr=local_address
         )
         transport.pause_reading()
         return SocketStream(transport, protocol)

src/anyio/itertools.py

@@ -141,7 +141,7 @@ async def __anext__(self) -> T:
 
 
 async def _operator_add(x: T, y: T) -> T:
-    return operator.add(x, y)
+    return operator.add(x, y)  # type: ignore[call-overload]
 
 
 async def accumulate(

src/anyio/pytest_plugin.py

@@ -202,12 +202,12 @@ def pytest_collection_finish(session: pytest.Session) -> None:
                         marks=[],
                     )
                 else:  # pytest 7.x
-                    callspec = CallSpec2(  # type: ignore[call-arg]
-                        funcargs={},
+                    callspec = CallSpec2(
+                        funcargs={},  # type: ignore[call-arg]
                         params={"anyio_backend": backend},
                         indices={"anyio_backend": param_index},
-                        arg2scope={"anyio_backend": Scope.Module},
-                        idlist=[backend],
+                        arg2scope={"anyio_backend": Scope.Module},  # type: ignore[call-arg]
+                        idlist=[backend],  # type: ignore[call-arg]
                         marks=[],
                     )
 

src/anyio/to_process.py

@@ -42,7 +42,7 @@
 _default_process_limiter: RunVar[CapacityLimiter] = RunVar("_default_process_limiter")
 
 
-async def run_sync(  # type: ignore[return]
+async def run_sync(  # type: ignore[return-value]
     func: Callable[[Unpack[PosArgsT]], T_Retval],
     *args: Unpack[PosArgsT],
     cancellable: bool = False,