Fix type resolution

HISTORY.md

@@ -19,6 +19,8 @@ Our backwards-compatibility policy can be found [here](https://github.com/python
   and {func}`cattrs.gen.typeddicts.make_dict_structure_fn` will use the value for the `use_alias` parameter from the given converter by default now.
   If you're using these functions directly, the old behavior can be restored by passing in the desired value directly.
   ([#596](https://github.com/python-attrs/cattrs/issues/596) [#660](https://github.com/python-attrs/cattrs/pull/660))
+- Fix unstructuring of generic classes with stringified annotations.
+  ([#661](https://github.com/python-attrs/cattrs/issues/661) [#662](https://github.com/python-attrs/cattrs/issues/662))
 
 ## 25.1.1 (2025-06-04)
 

src/cattrs/converters.py

@@ -1252,7 +1252,7 @@ def gen_unstructure_attrs_fromdict(
         attribs = fields(origin or cl)
         if attrs_has(cl) and any(isinstance(a.type, str) for a in attribs):
             # PEP 563 annotations - need to be resolved.
-            resolve_types(cl)
+            resolve_types(origin or cl)
         attrib_overrides = {
             a.name: self.type_overrides[a.type]
             for a in attribs

tests/test_generics_649.py

@@ -0,0 +1,25 @@
+"""Tests for PEP 649 (Deferred Evaluation Of Annotations Using Descriptors)."""
+
+from __future__ import annotations
+
+from typing import Generic, TypeVar
+
+from attrs import define
+
+from cattrs import Converter
+
+T = TypeVar("T")
+
+
+@define
+class GenericClass(Generic[T]):
+    t: T
+
+
+def test_generics_with_stringified_annotations():
+    """Type resolution works with stringified annotations."""
+    converter = Converter()
+    inst = GenericClass(42)
+    dct = converter.unstructure(inst, unstructure_as=GenericClass[int])
+    assert dct == {"t": 42}
+    assert converter.structure(dct, GenericClass[int])