Fix the worst issues

src/black/linegen.py

@@ -280,7 +280,7 @@ def visit_match_case(self, node: Node) -> Iterator[Line]:
 
     def visit_suite(self, node: Node) -> Iterator[Line]:
         """Visit a suite."""
-        if is_stub_suite(node, self.mode):
+        if is_stub_suite(node):
             yield from self.visit(node.children[2])
         else:
             yield from self.visit_default(node)
@@ -303,7 +303,7 @@ def visit_simple_stmt(self, node: Node) -> Iterator[Line]:
                 yield from self.line(-1)
 
         else:
-            if not node.parent or not is_stub_suite(node.parent, self.mode):
+            if not node.parent or not is_stub_suite(node.parent):
                 yield from self.line()
             yield from self.visit_default(node)
 

src/black/lines.py

@@ -828,16 +828,14 @@ def is_line_short_enough(  # noqa: C901
     if not line_str:
         line_str = line_to_string(line)
 
-    width = str_width if Preview.respect_east_asian_width in mode else len
-
     if line.contains_standalone_comments():
         return False
     if "\n" not in line_str:
         # No multiline strings (MLS) present
-        return width(line_str) <= mode.line_length
+        return str_width(line_str) <= mode.line_length
 
     first, *_, last = line_str.split("\n")
-    if width(first) > mode.line_length or width(last) > mode.line_length:
+    if str_width(first) > mode.line_length or str_width(last) > mode.line_length:
         return False
 
     # Traverse the AST to examine the context of the multiline string (MLS),

src/black/nodes.py

@@ -735,10 +735,10 @@ def is_funcdef(node: Node) -> bool:
     return node.type == syms.funcdef
 
 
-def is_stub_suite(node: Node, mode: Mode) -> bool:
+def is_stub_suite(node: Node) -> bool:
     """Return True if `node` is a suite with a stub body."""
     if node.parent is not None:
-        if Preview.dummy_implementations in mode and node.parent.type not in (
+        if node.parent.type not in (
             syms.funcdef,
             syms.async_funcdef,
             syms.classdef,