Fix hard dependency on anyio

Author: smurfix

pyproject.toml

@@ -15,9 +15,8 @@ classifiers = [
 requires-python = ">=3.10"
 dependencies = [
     "colorama; platform_system == 'Windows'",
-    "anyio ~= 4.0",
 ]
-version = "8.3.0.1"
+version = "8.3.0.2"
 
 [project.urls]
 Donate = "https://palletsprojects.com/donate"
@@ -50,13 +49,21 @@ pre-commit = [
     "pre-commit-uv",
 ]
 tests = [
+    "anyio",
     "pytest",
 ]
 typing = [
+    "anyio",
     "mypy",
     "pyright",
     "pytest",
 ]
+anyio = [
+    "anyio ~= 4.0",
+]
+trio = [
+    "trio ~= 0.22",
+]
 
 [build-system]
 requires = ["flit_core<4"]

src/asyncclick/core.py

@@ -20,8 +20,6 @@
 from itertools import repeat
 from types import TracebackType
 
-import anyio
-
 from . import types
 from ._utils import FLAG_NEEDS_VALUE
 from ._utils import UNSET
@@ -1540,16 +1538,31 @@ def __call__(
         """
         main = self.main
         opts: dict[str, t.Any] = {}
-        if _anyio_backend:
-            opts["backend"] = _anyio_backend
-        if _anyio_backend_options:
-            opts["backend_options"] = _anyio_backend_options
-        return anyio.run(self.main, main, args, kwargs, **opts)  # type:ignore
+        try:
+            import anyio
+        except ImportError:
+            pass
+        else:
+            if _anyio_backend:
+                opts["backend"] = _anyio_backend
+            if _anyio_backend_options:
+                opts["backend_options"] = _anyio_backend_options
+            return anyio.run(self.main, main, args, kwargs, **opts)  # type:ignore
+
+        if _anyio_backend == "trio":
+            import trio
+
+            return trio.run(self._main, main, args, kwargs)
+        if _anyio_backend == "asyncio":
+            import asyncio
+
+            return asyncio.run(self._main(main, args, kwargs))
+        raise RuntimeError(f"Backend {_anyio_backend!r} unknown")
 
     async def _main(
         self,
         main: t.Callable[..., t.Awaitable[t.Any]],
-        args: list[t.Any],
+        args: t.Sequence[t.Any],
         kwargs: dict[str, t.Any],
     ) -> t.Any:
         return await main(*args, **kwargs)