[pull] main from django:main

.github/pull_request_template.md

@@ -1,6 +1,6 @@
 #### Trac ticket number
 <!-- Replace XXXXX with the corresponding Trac ticket number. -->
-<!-- Or delete the line and write "N/A" if this is a trivial PR. -->
+<!-- Or delete the line and write "N/A - typo" for typo fixes. -->
 
 ticket-XXXXX
 

AUTHORS

@@ -35,6 +35,7 @@ answer newbie questions, and generally made Django that much better:
     Ahmad Al-Ibrahim
     Ahmed Eltawela <https://github.com/ahmedabt>
     Ahmed Nassar <https://ahmednassar7.github.io/>
+    Aina Anjary Fenomamy R. <anja1catus@gmail.com>
     ajs <adi@sieker.info>
     Akash Agrawal <akashrocksha@gmail.com>
     Akash Kumar Sen <akashkumarsen4@gmail.com>

django/forms/fields.py

@@ -965,7 +965,8 @@ def validate(self, value):
         if self.required and not value:
             raise ValidationError(self.error_messages["required"], code="required")
         # Validate that each value in the value list is in self.choices.
-        for val in value:
+        # Use set() to avoid redundant validation.
+        for val in set(value):
             if not self.valid_value(val):
                 raise ValidationError(
                     self.error_messages["invalid_choice"],

tests/forms_tests/field_tests/test_multiplechoicefield.py

@@ -76,3 +76,20 @@ def test_multiplechoicefield_changed(self):
     def test_disabled_has_changed(self):
         f = MultipleChoiceField(choices=[("1", "One"), ("2", "Two")], disabled=True)
         self.assertIs(f.has_changed("x", "y"), False)
+
+    def test_validate_duplicated_values(self):
+        f = MultipleChoiceField(
+            choices=[
+                ("1", "One"),
+                ("2", "Two"),
+                ("3", "Three"),
+                ("4", "Four"),
+                ("5", "Five"),
+            ]
+        )
+        self.assertIsNone(f.validate(["4", "4", "5", "5"]))
+
+    def test_validate_duplicated_invalid_values(self):
+        f = MultipleChoiceField(choices=[("1", "one"), ("2", "Two")])
+        with self.assertRaises(ValidationError):
+            f.validate(["1", "1", "invalid", "invalid"])