diff --git a/src/black/linegen.py b/src/black/linegen.py
index 2a224b1..29bd57e 100644
--- a/src/black/linegen.py
+++ b/src/black/linegen.py
@@ -200,30 +200,27 @@ def visit_dictsetmaker(self, node: Node) -> Iterator[Line]:
 
     def visit_funcdef(self, node: Node) -> Iterator[Line]:
         """Visit function definition."""
-        if Preview.annotation_parens not in self.mode:
-            yield from self.visit_stmt(node, keywords={"def"}, parens=set())
-        else:
-            yield from self.line()
+        yield from self.line()
 
-            # Remove redundant brackets around return type annotation.
-            is_return_annotation = False
-            for child in node.children:
-                if child.type == token.RARROW:
-                    is_return_annotation = True
-                elif is_return_annotation:
-                    if child.type == syms.atom and child.children[0].type == token.LPAR:
-                        if maybe_make_parens_invisible_in_atom(
-                            child,
-                            parent=node,
-                            remove_brackets_around_comma=False,
-                        ):
-                            wrap_in_parentheses(node, child, visible=False)
-                    else:
+        # Remove redundant brackets around return type annotation.
+        is_return_annotation = False
+        for child in node.children:
+            if child.type == token.RARROW:
+                is_return_annotation = True
+            elif is_return_annotation:
+                if child.type == syms.atom and child.children[0].type == token.LPAR:
+                    if maybe_make_parens_invisible_in_atom(
+                        child,
+                        parent=node,
+                        remove_brackets_around_comma=False,
+                    ):
                         wrap_in_parentheses(node, child, visible=False)
-                    is_return_annotation = False
+                else:
+                    wrap_in_parentheses(node, child, visible=False)
+                is_return_annotation = False
 
-            for child in node.children:
-                yield from self.visit(child)
+        for child in node.children:
+            yield from self.visit(child)
 
     def visit_match_case(self, node: Node) -> Iterator[Line]:
         """Visit either a match or case statement."""
diff --git a/src/black/mode.py b/src/black/mode.py
index 125970e..afa403e 100644
--- a/src/black/mode.py
+++ b/src/black/mode.py
@@ -149,7 +149,6 @@ def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> b
 class Preview(Enum):
     """Individual preview style features."""
 
-    annotation_parens = auto()
     prefer_splitting_right_hand_side_of_assignments = auto()
     # NOTE: string_processing requires wrap_long_dict_values_in_parens
     # for https://github.com/psf/black/issues/3117 to be fixed.