Exception thrown when creating migration

[lecneri]

Bug Report

Q	A
Version	3.8.4

Summary

Exception occurs at Doctrine\DBAL\Schema\Index::__addColumn while I try to make a migration with a table that has a function as index instead of column.
I believe this exception happens because I'm using a function inside the index in MySQL (8.0.35)

Current behaviour

I try to make a a migration and I an error is thrown. Here I paste the log
[2024-05-08T15:30:30.136808+00:00] console.CRITICAL: Error thrown while running command "make:migration -vvv". Message: "Doctrine\DBAL\Schema\Index::_addColumn(): Argument #1 ($column) must be of type string, null given, called in /home/len/projetos/dbal-bug-reproduce/vendor/doctrine/dbal/src/Schema/Index.php on line 72" {"exception":"[object] (TypeError(code: 0): Doctrine\\DBAL\\Schema\\Index::_addColumn(): Argument #1 ($column) must be of type string, null given, called in /home/len/projetos/dbal-bug-reproduce/vendor/doctrine/dbal/src/Schema/Index.php on line 72 at /home/len/projetos/dbal-bug-reproduce/vendor/doctrine/dbal/src/Schema/Index.php:81)","command":"make:migration -vvv","message":"Doctrine\\DBAL\\Schema\\Index::_addColumn(): Argument #1 ($column) must be of type string, null given, called in /home/len/projetos/dbal-bug-reproduce/vendor/doctrine/dbal/src/Schema/Index.php on line 72"} []

How to reproduce

1 - I started with composer create-project symfony/skeleton <project_name>
2 - composer req orm
3 - composer req --dev migrations maker debug log (last 2 is to make life easier)
4 - connect to MySQL and create database and table

CREATE TABLE foo (id int not null auto_increment, bugged_column datetime, primary key(id));

5 - create the index on bugged_column as follow

CREATE INDEX idx_bugged_column ON foo ((date(bugged_column)));

this will create an date based index, removing the time from column
6 - php bin/console make:migration
7 - Watch the crash

As far as I noticed, the error happens at Doctrine\DBAL\Schema\Index line 72, because the index created is not associated to any column directly, making the query return columns key with 1 line, but with a null value

this happens around line 1472 of Doctrine\DBAL\Schema\AbstractSchemaManager::_getPortableTableIndexesList
$result[$keyName]['columns'][] = $tableIndex['column_name']; // column name is null as returned from query in mysql
When I replaced with
$result[$keyName]['columns'][] = $tableIndex['column_name'] ?? ''; migration succeded, but I don't know what will happen leaving this way.
If you try to check before hand if the value is null it'll throw an error requiring columns

if ( $tableIndex['column_name'] !== null ) 
   $result[$keyName]['columns'][]            = $tableIndex['column_name'];

Expected behaviour

The expected behaviour is to execute the migration command correctly, creating a new migration.

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I have a table with few hundred millions rows and I have a column datetime and few systems in php, power bi, excel querying this table making this date(column) instead of between yyyy-mm-dd 00:00:00 and yyyy-mm-dd 23:59:59, which was triggering a full table scan and this index improved performance a lot