Fix regression

.github/workflows/main.yml

@@ -5,7 +5,6 @@ on:
   push:
     branches: ["main"]
   pull_request:
-    branches: ["main"]
   workflow_dispatch:
 
 jobs:
@@ -47,7 +46,7 @@ jobs:
 
     steps:
       - uses: "actions/checkout@v3"
-      
+
       - uses: "actions/setup-python@v4"
         with:
           cache: "pip"
@@ -76,7 +75,7 @@ jobs:
         with:
           name: "html-report"
           path: "htmlcov"
-      
+
       - name: "Make badge"
         if: github.ref == 'refs/heads/main'
         uses: "schneegans/dynamic-badges-action@v1.4.0"

HISTORY.md

@@ -1,5 +1,10 @@
 # History
 
+## 23.2.2 (UNRELEASED)
+
+- Fix a regression when unstructuring `Any | None`.
+  ([#453](https://github.com/python-attrs/cattrs/issues/453))
+
 ## 23.2.1 (2023-11-18)
 
 - Fix unnecessary `typing_extensions` import on Python 3.11.

src/cattrs/converters.py

@@ -954,7 +954,12 @@ def gen_unstructure_optional(self, cl: Type[T]) -> Callable[[T], Any]:
         """Generate an unstructuring hook for optional types."""
         union_params = cl.__args__
         other = union_params[0] if union_params[1] is NoneType else union_params[1]
-        handler = self._unstructure_func.dispatch(other)
+
+        # TODO: Remove this special case when we make unstructuring Any consistent.
+        if other is Any:
+            handler = self.unstructure
+        else:
+            handler = self._unstructure_func.dispatch(other)
 
         def unstructure_optional(val, _handler=handler):
             return None if val is None else _handler(val)

tests/test_optionals.py

@@ -1,8 +1,10 @@
-from typing import NewType, Optional
+from typing import Any, NewType, Optional
 
 import pytest
 from attrs import define
 
+from cattrs import Converter
+
 from ._compat import is_py310_plus
 
 
@@ -39,3 +41,13 @@ class ModelWithFoo:
         "total_foo": "bar",
         "maybe_foo": "is it a bar?",
     }
+
+
+def test_optional_any(converter: Converter):
+    """Unstructuring Any|None is equivalent to unstructuring as v.__class__."""
+
+    @define
+    class A:
+        pass
+
+    assert converter.unstructure(A(), Optional[Any]) == {}