Fixed #36086 -- Fixed crash when using GeneratedField with non-AutoField pk.

The previous logic was systematically attempting to retrieve last_insert_id
even for models without an AutoField primary key when they had a GeneratedField
on backends that can't return columns from INSERT.

The issue affected MySQL, SQLite < 3.35, and Oracle when the use_returning_into
option was disabled and could result in either crashes when the non-auto
primary key wasn't an IntegerField subclass or silent misassignment of bogus
insert ids (0 or the previous auto primary key insert value) to the first
defined generated field value.

1 files changed, 10 insertions, 4 deletions

diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index 0d5cd764da..6f90f11f1b 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -8,7 +8,7 @@ from django.core.exceptions import EmptyResultSet, FieldError, FullResultSet
 from django.db import DatabaseError, NotSupportedError
 from django.db.models.constants import LOOKUP_SEP
 from django.db.models.expressions import ColPairs, F, OrderBy, RawSQL, Ref, Value
-from django.db.models.fields import composite
+from django.db.models.fields import AutoField, composite
 from django.db.models.functions import Cast, Random
 from django.db.models.lookups import Lookup
 from django.db.models.query_utils import select_related_descend
@@ -1910,17 +1910,23 @@ class SQLInsertCompiler(SQLCompiler):
                     )
                 ]
                 cols = [field.get_col(opts.db_table) for field in self.returning_fields]
-            else:
-                cols = [opts.pk.get_col(opts.db_table)]
+            elif returning_fields and isinstance(
+                returning_field := returning_fields[0], AutoField
+            ):
+                cols = [returning_field.get_col(opts.db_table)]
                 rows = [
                     (
                         self.connection.ops.last_insert_id(
                             cursor,
                             opts.db_table,
-                            opts.pk.column,
+                            returning_field.column,
                         ),
                     )
                 ]
+            else:
+                # Backend doesn't support returning fields and no auto-field
+                # that can be retrieved from `last_insert_id` was specified.
+                return []
         converters = self.get_converters(cols)
         if converters:
             rows = self.apply_converters(rows, converters)