Fix annotation evaluation on inherited dataclasses

The `_get_fields()` function evaluated annotations in the context of
the given dataclass, but each annotation should be evaluated in the
context of its surrounding class.

src/dataclass_binder/_impl.py

@@ -164,11 +164,11 @@ def _get_fields(cls: type) -> Iterator[tuple[str, type]]:
 
     fields_by_name = {field.name: field for field in fields(cls)}
 
-    # Note: getmodule() can return None, but the end result is still fine.
-    cls_globals = getattr(getmodule(cls), "__dict__", {})
-    cls_locals = vars(cls)
-
     for field_container in reversed(cls.__mro__):
+        # Note: getmodule() can return None, but the end result is still fine.
+        cls_globals = getattr(getmodule(field_container), "__dict__", {})
+        cls_locals = vars(field_container)
+
         for name, annotation in get_annotations(field_container).items():
             field = fields_by_name[name]
             if not field.init:

tests/example.py

@@ -1,13 +1,16 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from typing import TypeAlias
+
+URL: TypeAlias = str
 
 
 @dataclass(frozen=True)
 class Config:
     """Configuration for an example service."""
 
-    database_url: str
+    database_url: URL
     """The URL of the database to connect to."""
 
     port: int = 12345

tests/test_parsing.py

@@ -133,21 +133,21 @@ def test_bind_inheritance() -> None:
     """A dataclass inheriting from another dataclass accepts fields from both the base and the subclass."""
 
     @dataclass(frozen=True)
-    class ExtendedConfig(Config):
+    class ExtendedConfig(example.Config):
+        """Inheriting from a class in another module complicates the annotation evaluation."""
+
         dry_run: bool = False
 
     with stream_text(
         """
-        rest-api-port = 6000
-        feed-job-prefixes = ["MIX1:", "MIX2:", "MIX3:"]
+        database-url = "postgresql://smaug:gold@mountain/hoard"
         dry-run = true
         """
     ) as stream:
         config = Binder(ExtendedConfig).parse_toml(stream)
 
-    assert config.rest_api_port == 6000
-    assert config.feed_job_prefixes == ("MIX1:", "MIX2:", "MIX3:")
-    assert config.import_max_nr_hours == 24
+    assert config.database_url == "postgresql://smaug:gold@mountain/hoard"
+    assert config.port == 12345
     assert config.dry_run is True