pythongh-109543: Remove unnecessary hasattr check (python#109544)

Also added a new test case covering the scenario I thought this
might be about.

Author: JelleZijlstra

Lib/test/test_typing.py

@@ -7586,6 +7586,17 @@ def test_total(self):
         self.assertEqual(Options.__required_keys__, frozenset())
         self.assertEqual(Options.__optional_keys__, {'log_level', 'log_path'})
 
+    def test_total_inherits_non_total(self):
+        class TD1(TypedDict, total=False):
+            a: int
+
+        self.assertIs(TD1.__total__, False)
+
+        class TD2(TD1):
+            b: str
+
+        self.assertIs(TD2.__total__, True)
+
     def test_optional_keys(self):
         class Point2Dor3D(Point2D, total=False):
             z: int

Lib/typing.py

@@ -2886,8 +2886,7 @@ def __new__(cls, name, bases, ns, total=True):
         tp_dict.__annotations__ = annotations
         tp_dict.__required_keys__ = frozenset(required_keys)
         tp_dict.__optional_keys__ = frozenset(optional_keys)
-        if not hasattr(tp_dict, '__total__'):
-            tp_dict.__total__ = total
+        tp_dict.__total__ = total
         return tp_dict
 
     __call__ = dict  # static method

Misc/NEWS.d/next/Library/2023-09-18-07-43-22.gh-issue-109543.1tOGoV.rst

@@ -0,0 +1,2 @@
+Remove unnecessary :func:`hasattr` check during :data:`typing.TypedDict`
+creation.