Add is_unreachable to Block.__init__

Author: brianschubert

mypy/nodes.py

@@ -1263,15 +1263,15 @@ class Block(Statement):
 
     __match_args__ = ("body", "is_unreachable")
 
-    def __init__(self, body: list[Statement]) -> None:
+    def __init__(self, body: list[Statement], *, is_unreachable: bool = False) -> None:
         super().__init__()
         self.body = body
         # True if we can determine that this block is not executed during semantic
         # analysis. For example, this applies to blocks that are protected by
         # something like "if PY3:" when using Python 2. However, some code is
         # only considered unreachable during type checking and this is not true
         # in those cases.
-        self.is_unreachable = False
+        self.is_unreachable = is_unreachable
 
     def accept(self, visitor: StatementVisitor[T]) -> T:
         return visitor.visit_block(self)

mypy/treetransform.py

@@ -276,9 +276,7 @@ def visit_nonlocal_decl(self, node: NonlocalDecl) -> NonlocalDecl:
         return NonlocalDecl(node.names.copy())
 
     def visit_block(self, node: Block) -> Block:
-        new = Block(self.statements(node.body))
-        new.is_unreachable = node.is_unreachable
-        return new
+        return Block(self.statements(node.body), is_unreachable=node.is_unreachable)
 
     def visit_decorator(self, node: Decorator) -> Decorator:
         # Note that a Decorator must be transformed to a Decorator.