fix: use a correct recursive definition for DumperKey

Already supported in current Mypy: python/mypy#731.

The definition of DumperKey was wrong anyway, in a way causing mypy to
crash: see python/mypy#14000.

psycopg/psycopg/abc.py

@@ -29,10 +29,7 @@
 Params: TypeAlias = Union[Sequence[Any], Mapping[str, Any]]
 ConnectionType = TypeVar("ConnectionType", bound="BaseConnection[Any]")
 PipelineCommand: TypeAlias = Callable[[], None]
-
-# TODO: make it recursive when mypy will support it
-# DumperKey: TypeAlias = Union[type, Tuple[Union[type, "DumperKey"]]]
-DumperKey: TypeAlias = Union[type, Tuple[type, ...]]
+DumperKey: TypeAlias = Union[type, Tuple["DumperKey", ...]]
 
 # Waiting protocol types
 

psycopg/psycopg/adapt.py

@@ -5,7 +5,7 @@
 # Copyright (C) 2020 The Psycopg Team
 
 from abc import ABC, abstractmethod
-from typing import Any, Optional, Type, Tuple, Union, TYPE_CHECKING
+from typing import Any, Optional, Type, TYPE_CHECKING
 
 from . import pq, abc
 from . import _adapters_map
@@ -91,7 +91,7 @@ def quote(self, obj: Any) -> Buffer:
             rv = rv.replace(b"\\", b"\\\\")
         return rv
 
-    def get_key(self, obj: Any, format: PyFormat) -> Union[type, Tuple[type, ...]]:
+    def get_key(self, obj: Any, format: PyFormat) -> abc.DumperKey:
         """
         Implementation of the `~psycopg.abc.Dumper.get_key()` member of the
         `~psycopg.abc.Dumper` protocol. Look at its definition for details.

psycopg/psycopg/types/array.py

@@ -121,7 +121,7 @@ def get_key(self, obj: List[Any], format: PyFormat) -> DumperKey:
             return self.cls
 
         sd = self._tx.get_dumper(item, format)
-        return (self.cls, sd.get_key(item, format))  # type: ignore
+        return (self.cls, sd.get_key(item, format))
 
     def upgrade(self, obj: List[Any], format: PyFormat) -> "BaseListDumper":
         # If we have an oid we don't need to upgrade
@@ -223,7 +223,7 @@ def get_key(self, obj: List[Any], format: PyFormat) -> DumperKey:
             return (self.cls,)
 
         sd = self._tx.get_dumper(item, format)
-        return (self.cls, sd.get_key(item, format))  # type: ignore
+        return (self.cls, sd.get_key(item, format))
 
     def upgrade(self, obj: List[Any], format: PyFormat) -> "BaseListDumper":
         # If we have an oid we don't need to upgrade

psycopg/psycopg/types/multirange.py

@@ -154,7 +154,7 @@ def get_key(self, obj: Multirange[Any], format: PyFormat) -> DumperKey:
         item = self._get_item(obj)
         if item is not None:
             sd = self._tx.get_dumper(item, self._adapt_format)
-            return (self.cls, sd.get_key(item, format))  # type: ignore
+            return (self.cls, sd.get_key(item, format))
         else:
             return (self.cls,)
 

psycopg/psycopg/types/range.py

@@ -259,7 +259,7 @@ def get_key(self, obj: Range[Any], format: PyFormat) -> DumperKey:
         item = self._get_item(obj)
         if item is not None:
             sd = self._tx.get_dumper(item, self._adapt_format)
-            return (self.cls, sd.get_key(item, format))  # type: ignore
+            return (self.cls, sd.get_key(item, format))
         else:
             return (self.cls,)
 

pyproject.toml

@@ -35,6 +35,7 @@ files = [
 warn_unused_ignores = true
 show_error_codes = true
 strict = true
+enable_recursive_aliases = true
 
 [[tool.mypy.overrides]]
 module = [

tests/adapters_example.py

@@ -1,4 +1,4 @@
-from typing import Optional, Tuple, Union
+from typing import Optional
 
 from psycopg import pq
 from psycopg.abc import Dumper, Loader, AdaptContext, PyFormat, Buffer
@@ -43,9 +43,3 @@ def __init__(self, oid: int, context: Optional[AdaptContext] = None):
 
     def load(self, data: Buffer) -> str:
         return (bytes(data) * 2).decode()
-
-
-# This should be the definition of psycopg.adapt.DumperKey, but mypy doesn't
-# support recursive types. When it will, this statement will give an error
-# (unused type: ignore) so we can fix our definition.
-_DumperKey = Union[type, Tuple[Union[type, "_DumperKey"]]]  # type: ignore