Unexpected migration loop: persistent schema diff for DOUBLE PRECISION column with default value

[axzx]

Bug Report

Q	A
Version	4.0.0

• PHP 8.5.2 (cli) (built: Feb 3 2026 02:28:01) (ZTS)
• mysql Ver 8.0.32 for Linux on x86_64 (MySQL Community Server - GPL)
• Symfony 8.0
• DoctrineMigrationsBundle 4.0.0
• doctrine/dbal 4.4.1
• doctrine/doctrine-bundle 3.2.2

Summary

I am experiencing an issue where doctrine:migrations:diff constantly generates the same migration for a DOUBLE PRECISION column, even after the migration has been executed. It seems like Doctrine detects a difference between the database state and the mapping, but they are actually in sync.

Entity Mapping

#[ORM\Column(options: ['default' => 0])]
private float $amountDone = 0;

Generated Migration

Each time I run bin/console doctrine:migrations:diff, the following SQL is generated:

public function up(Schema $schema): void
{
    $this->addSql('ALTER TABLE contract__element CHANGE amount_done amount_done DOUBLE PRECISION DEFAULT 0 NOT NULL');
}

public function down(Schema $schema): void
{
    $this->addSql('ALTER TABLE contract__element CHANGE amount_done amount_done DOUBLE PRECISION DEFAULT \'0\' NOT NULL');
}

[greg0ire]

What is your version of doctrine/dbal?

[axzx]

What is your version of doctrine/dbal?

doctrine/dbal 4.4.1
doctrine/doctrine-bundle 3.2.2

[greg0ire]

OK, because I tried reproducing this bug with the DBAL API but couldn't. I guess you will have to debug from this point: https://github.com/doctrine/migrations/blob/ffd8355cdd8505fc650d9604f058bf62aedd80a1/src/Generator/DiffGenerator.php#L97

The first thing to understand would be whether $fromSchema or $toSchema is wrong.

[axzx]

$fromSchema:

"amount_done" => Doctrine\DBAL\Schema\Column^ {#841
          #_name: "amount_done"
          #isNameInitialized: true
          #_namespace: null
          #_quoted: false
          -identifiers: array:1 [ …1]
          -validateFuture: true
          #name: Doctrine\DBAL\Schema\Name\UnqualifiedName^ {#843 …1}
          #_type: Doctrine\DBAL\Types\FloatType^ {#427}
          #_length: null
          #_precision: 22
          #_scale: 0
          #_unsigned: false
          #_fixed: false
          #_notnull: true
          #_default: "0"
          #_autoincrement: false
          #_values: []
          #_platformOptions: array:2 [ …2]
          #_columnDefinition: null
          #_comment: ""
        }

$toSchema:

"amount_done" => Doctrine\DBAL\Schema\Column^ {#1993
          #_name: "amount_done"
          #isNameInitialized: true
          #_namespace: null
          #_quoted: false
          -identifiers: array:1 [ …1]
          -validateFuture: true
          #name: Doctrine\DBAL\Schema\Name\UnqualifiedName^ {#1995 …1}
          #_type: Doctrine\DBAL\Types\FloatType^ {#427}
          #_length: null
          #_precision: null
          #_scale: 0
          #_unsigned: false
          #_fixed: false
          #_notnull: true
          #_default: 0
          #_autoincrement: false
          #_values: []
          #_platformOptions: []
          #_columnDefinition: null
          #_comment: ""
        }

[greg0ire]

OK, so the from schema a.k.a the introspected schema is wrong? It's built like this: https://github.com/doctrine/migrations/blob/ffd8355cdd8505fc650d9604f058bf62aedd80a1/src/Generator/DiffGenerator.php#L133-L136

Maybe that can be reproduced in a test.

[axzx]

OK, so the from schema a.k.a the introspected schema is wrong? It's built like this: https://github.com/doctrine/migrations/blob/ffd8355cdd8505fc650d9604f058bf62aedd80a1/src/Generator/DiffGenerator.php#L133-L136

Maybe that can be reproduced in a test.

I think my report here can be closed because the error is in doctrine/dbal.
Support for specific types is missing.

Probably here:

dbal/src/Schema/MySQLSchemaManager.php

Line 198 in 8381210

$columnDefault = $this->parseMySQLColumnDefault($dbType, $tableColumn['default']);

[greg0ire]

I transferred the issue.