is_named_instance should be a TypeGuard (#13543)

python · Aug 28, 2022 · 1a3d601 · 1a3d601
1 parent 6250063
commit 1a3d601
Show file tree

Hide file tree

Showing 2 changed files with 3 additions and 3 deletions.
diff --git a/mypy/checker.py b/mypy/checker.py
@@ -4246,7 +4246,7 @@ def get_types_from_except_handler(self, typ: Type, n: Expression) -> list[Type]:
  for item in typ.relevant_items()
  for union_typ in self.get_types_from_except_handler(item, n)
  ]
- elif isinstance(typ, Instance) and is_named_instance(typ, "builtins.tuple"):
+ elif is_named_instance(typ, "builtins.tuple"):
  # variadic tuple
  return [typ.args[0]]
  else:

diff --git a/mypy/types.py b/mypy/types.py
@@ -17,7 +17,7 @@
  Union,
  cast,
 )
-from typing_extensions import Final, TypeAlias as _TypeAlias, overload
+from typing_extensions import Final, TypeAlias as _TypeAlias, TypeGuard, overload
 
 import mypy.nodes
 from mypy.bogus_type import Bogus
@@ -3172,7 +3172,7 @@ def strip_type(typ: Type) -> Type:
  return orig_typ
 
 
-def is_named_instance(t: Type, fullnames: str | tuple[str, ...]) -> bool:
+def is_named_instance(t: Type, fullnames: str | tuple[str, ...]) -> TypeGuard[Instance]:
  if not isinstance(fullnames, tuple):
  fullnames = (fullnames,)