[3.10] bpo-46032: Check types in singledispatch's register() at declaration time (GH-30050) (GH-30254)
The registry() method of functools.singledispatch() functions checks now
the first argument or the first parameter annotation and raises a TypeError if it is
not supported. Previously unsupported "types" were ignored (e.g. typing.List[int])
or caused an error at calling time (e.g. list[int]).
(cherry picked from commit 078abb676cf759b1e960f78390b6e80f256f0255)
diff --git a/Lib/functools.py b/Lib/functools.py
index 77ec852..305ceb4 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -740,6 +740,7 @@ def _compose_mro(cls, types):
# Remove entries which are already present in the __mro__ or unrelated.
def is_related(typ):
return (typ not in bases and hasattr(typ, '__mro__')
+ and not isinstance(typ, GenericAlias)
and issubclass(cls, typ))
types = [n for n in types if is_related(n)]
# Remove entries which are strict bases of other entries (they will end up
@@ -837,6 +838,9 @@ def dispatch(cls):
dispatch_cache[cls] = impl
return impl
+ def _is_valid_dispatch_type(cls):
+ return isinstance(cls, type) and not isinstance(cls, GenericAlias)
+
def register(cls, func=None):
"""generic_func.register(cls, func) -> func
@@ -844,9 +848,15 @@ def register(cls, func=None):
"""
nonlocal cache_token
- if func is None:
- if isinstance(cls, type):
+ if _is_valid_dispatch_type(cls):
+ if func is None:
return lambda f: register(cls, f)
+ else:
+ if func is not None:
+ raise TypeError(
+ f"Invalid first argument to `register()`. "
+ f"{cls!r} is not a class."
+ )
ann = getattr(cls, '__annotations__', {})
if not ann:
raise TypeError(
@@ -859,11 +869,12 @@ def register(cls, func=None):
# only import typing if annotation parsing is necessary
from typing import get_type_hints
argname, cls = next(iter(get_type_hints(func).items()))
- if not isinstance(cls, type):
+ if not _is_valid_dispatch_type(cls):
raise TypeError(
f"Invalid annotation for {argname!r}. "
f"{cls!r} is not a class."
)
+
registry[cls] = func
if cache_token is None and hasattr(cls, '__abstractmethods__'):
cache_token = get_cache_token()