Improve django.forms (#221)

A collection of small improvements to the `django.forms.forms` and `django.forms.boundfield` modules. The most impactful change is declaring `BaseForm.cleaned_data` to be a `dict`.

The other changes are described in the commit messages.

django-stubs/forms/boundfield.pyi

@@ -1,3 +1,4 @@
+from collections.abc import Iterable
 from typing import Any
 
 from django.forms.fields import Field
@@ -18,9 +19,10 @@ class BoundField:
     label: str = ...
     help_text: str = ...
     def __init__(self, form: BaseForm, field: Field, name: str) -> None: ...
+    @property
     def subwidgets(self) -> list[BoundWidget]: ...
     def __bool__(self) -> bool: ...
-    def __iter__(self) -> Any: ...
+    def __iter__(self) -> Iterable[BoundWidget]: ...
     def __len__(self) -> int: ...
     def __getitem__(
         self, idx: int | slice | str

django-stubs/forms/forms.pyi

@@ -1,4 +1,4 @@
-from collections.abc import Iterator, Mapping, Sequence
+from collections.abc import Iterator, Mapping
 from typing import Any
 
 from django.core.exceptions import ValidationError as ValidationError
@@ -15,11 +15,9 @@ from django.utils.safestring import SafeText
 class DeclarativeFieldsMetaclass(MediaDefiningClass): ...
 
 class BaseForm:
-    class Meta:
-        fields: Sequence[str] = ...
     _meta: Options[Any]
-    default_renderer: Any = ...
-    field_order: Any = ...
+    default_renderer: type[BaseRenderer] = ...
+    field_order: list[str] | None = ...
     use_required_attribute: bool = ...
     is_bound: bool = ...
     data: dict[str, Any] = ...
@@ -32,7 +30,7 @@ class BaseForm:
     empty_permitted: bool = ...
     fields: dict[str, Any] = ...
     renderer: BaseRenderer = ...
-    cleaned_data: Any = ...
+    cleaned_data: dict[str, Any] = ...
     def __init__(
         self,
         data: Mapping[str, Any] | None = ...,
@@ -43,9 +41,9 @@ class BaseForm:
         error_class: type[ErrorList] = ...,
         label_suffix: str | None = ...,
         empty_permitted: bool = ...,
-        field_order: Any | None = ...,
+        field_order: list[str] | None = ...,
         use_required_attribute: bool | None = ...,
-        renderer: Any = ...,
+        renderer: type[BaseRenderer] | None = ...,
     ) -> None: ...
     def order_fields(self, field_order: list[str] | None) -> None: ...
     def __iter__(self) -> Iterator[BoundField]: ...
@@ -60,17 +58,17 @@ class BaseForm:
     def as_p(self) -> SafeText: ...
     def non_field_errors(self) -> ErrorList: ...
     def add_error(self, field: str | None, error: ValidationError | str) -> None: ...
-    def has_error(self, field: Any, code: Any | None = ...) -> Any: ...
+    def has_error(self, field: str, code: str | None = ...) -> bool: ...
     def full_clean(self) -> None: ...
     def clean(self) -> dict[str, Any]: ...
     def has_changed(self) -> bool: ...
     @property
     def changed_data(self) -> list[str]: ...
     @property
     def media(self) -> Media: ...
-    def is_multipart(self) -> Any: ...
-    def hidden_fields(self) -> Any: ...
-    def visible_fields(self) -> Any: ...
+    def is_multipart(self) -> bool: ...
+    def hidden_fields(self) -> list[BoundField]: ...
+    def visible_fields(self) -> list[BoundField]: ...
     def get_initial_for_field(self, field: Field, field_name: str) -> Any: ...
     def _html_output(
         self,

django-stubs/forms/models.pyi

@@ -280,7 +280,6 @@ class ModelChoiceField(ChoiceField):
 
 class ModelMultipleChoiceField(ModelChoiceField):
     disabled: bool
-    empty_label: None
     help_text: str
     required: bool
     show_hidden_initial: bool