id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
34128	django re-using the name of a squashed migration leads to CircularDependencyError	Johannes 'fish' Ziemke	nobody	"Hi,

I've squashed two migrations,  creating this file:
{{{
# Generated by Django 3.2 on 2022-10-30 14:15

from django.db import migrations, models


class Migration(migrations.Migration):

    replaces = [('api', '0005_achievement_difficulty'), ('api', '0006_alter_achievement_difficulty')]

    dependencies = [
        ('api', '0004_achievement_squashed_0005_alter_achievement_submission'),
    ]

    operations = [
        migrations.AddField(
            model_name='achievement',
            name='difficulty',
            field=models.SmallIntegerField(default=0),
        ),
    ]
}}}

After rolling out the change, I've deleted 0005_achievement_difficulty and 0006_alter_achievement_difficulty.

Now I've did some more changes to the model, causing django to create the following 0006_alter_achievement_difficulty:
{{{
# Generated by Django 3.2 on 2022-10-31 12:59

from django.db import migrations, models


class Migration(migrations.Migration):

    dependencies = [
        ('api', '0005_achievement_difficulty_squashed_0006_alter_achievement_difficulty'),
    ]

    operations = [
        migrations.AlterField(
            model_name='achievement',
            name='difficulty',
            field=models.SmallIntegerField(),
        ),
    ]
}}}

Which leads to the following error:
{{{
  File ""/usr/local/lib/python3.10/site-packages/django/db/migrations/graph.py"", line 274, in ensure_not_cyclic
    raise CircularDependencyError("", "".join(""%s.%s"" % n for n in cycle))
django.db.migrations.exceptions.CircularDependencyError: api.0005_achievement_difficulty_squashed_0006_alter_achievement_difficulty
}}}

Renaming the migration file to 0006_alter_achievement_difficulty_new.py fixed it.

While I wouldn't rule out a mistake on my side, it seems the way django creates the migration name can lead to new migrations being named like squashed and removed ones, causing the dependency check to wrongfully assume the squashed migration would depend on it."	Uncategorized	closed	Database layer (models, ORM)	3.2	Normal	invalid			Unreviewed	0	0	0	0	0	0