Fixed #35560 -- Made Model.full_clean() ignore GeneratedFields for constraints.

Accessing generated field values on unsaved models caused a crash when
validating CheckConstraints and UniqueConstraints with expressions.

tests/model_fields/models.py

@@ -609,3 +609,79 @@ class GeneratedModelNullVirtual(models.Model):
 
     class Meta:
         required_db_features = {"supports_virtual_generated_columns"}
+
+
+class GeneratedModelBase(models.Model):
+    a = models.IntegerField()
+    a_squared = models.GeneratedField(
+        expression=F("a") * F("a"),
+        output_field=models.IntegerField(),
+        db_persist=True,
+    )
+
+    class Meta:
+        abstract = True
+
+
+class GeneratedModelVirtualBase(models.Model):
+    a = models.IntegerField()
+    a_squared = models.GeneratedField(
+        expression=F("a") * F("a"),
+        output_field=models.IntegerField(),
+        db_persist=False,
+    )
+
+    class Meta:
+        abstract = True
+
+
+class GeneratedModelCheckConstraint(GeneratedModelBase):
+    class Meta:
+        required_db_features = {
+            "supports_stored_generated_columns",
+            "supports_table_check_constraints",
+        }
+        constraints = [
+            models.CheckConstraint(
+                condition=models.Q(a__gt=0),
+                name="Generated model check constraint a > 0",
+            )
+        ]
+
+
+class GeneratedModelCheckConstraintVirtual(GeneratedModelVirtualBase):
+    class Meta:
+        required_db_features = {
+            "supports_virtual_generated_columns",
+            "supports_table_check_constraints",
+        }
+        constraints = [
+            models.CheckConstraint(
+                condition=models.Q(a__gt=0),
+                name="Generated model check constraint virtual a > 0",
+            )
+        ]
+
+
+class GeneratedModelUniqueConstraint(GeneratedModelBase):
+    class Meta:
+        required_db_features = {
+            "supports_stored_generated_columns",
+            "supports_table_check_constraints",
+        }
+        constraints = [
+            models.UniqueConstraint(F("a"), name="Generated model unique constraint a"),
+        ]
+
+
+class GeneratedModelUniqueConstraintVirtual(GeneratedModelVirtualBase):
+    class Meta:
+        required_db_features = {
+            "supports_virtual_generated_columns",
+            "supports_expression_indexes",
+        }
+        constraints = [
+            models.UniqueConstraint(
+                F("a"), name="Generated model unique constraint virtual a"
+            ),
+        ]