Raise an Error When Computed Field Overrides Field (#7346)

Co-authored-by: Adrian Garcia Badaracco <1755071+adriangb@users.noreply.github.com>

pydantic/_internal/_fields.py

@@ -19,6 +19,7 @@
     from ..fields import FieldInfo
     from ..main import BaseModel
     from ._dataclasses import StandardDataclass
+    from ._decorators import DecoratorInfos
 
 
 def get_type_hints_infer_globalns(
@@ -196,6 +197,11 @@ def collect_model_fields(  # noqa: C901
             except AttributeError:
                 pass  # indicates the attribute was on a parent class
 
+        # Use cls.__dict__['__pydantic_decorators__'] instead of cls.__pydantic_decorators__
+        # to make sure the decorators have already been built for this exact class
+        decorators: DecoratorInfos = cls.__dict__['__pydantic_decorators__']
+        if ann_name in decorators.computed_fields:
+            raise ValueError("you can't override a field with a computed field")
         fields[ann_name] = field_info
 
     if typevars_map:

tests/test_computed_fields.py

@@ -741,3 +741,16 @@ def double_x(self) -> T:
 
     with pytest.warns(UserWarning, match='Expected `int` but got `str` - serialized value may not be as expected'):
         B[int]().model_dump()
+
+
+def test_computed_field_override_raises():
+    class Model(BaseModel):
+        name: str = 'foo'
+
+    with pytest.raises(ValueError, match="you can't override a field with a computed field"):
+
+        class SubModel(Model):
+            @computed_field
+            @property
+            def name(self) -> str:
+                return 'bar'