Add the abortIf check when generating a migration.

[VincentLanglet]

Feature Request

Q	A
New Feature	not really
BC Break	don't know

Summary

When doing doctrine:migration:diff I get something like this:

    /**
     * @param Schema $schema
     *
     * @throws MigrationException|DBALException
     */
    public function up(Schema $schema): void
    {
        $this->abortIf($this->connection->getDatabasePlatform()->getName() !== 'mysql', 'Migration can only be executed safely on \'mysql\'.');

        $this->addSql('ALTER TABLE asv_contract_operation CHANGE eligible_for_voucher eligible_for_bonus TINYINT(1) DEFAULT \'0\' NOT NULL');
    }

But when doing doctrine:migration:generate I get:

    /**
     * @param Schema $schema
     *
     * @throws MigrationException|DBALException
     */
    public function up(Schema $schema): void
    {
    }

I would expect to get:

    /**
     * @param Schema $schema
     *
     * @throws MigrationException|DBALException
     */
    public function up(Schema $schema): void
    {
$this->abortIf($this->connection->getDatabasePlatform()->getName() !== 'mysql', 'Migration can only be executed safely on \'mysql\'.');

    }

[goetas]

Duplicate of doctrine/DoctrineMigrationsBundle#270, will be solved with the v3.0

[alcaeus]

In addition to the above, the reason the abortIf call is there because the auto-generated migration (which is done using diff) can only support the current platform. When calling the generate command, all you get is an empty migration with no database-specific code in it. If you add code that only works on a specific platform, it's your responsibility to do so.

This doesn't mean we won't add the call ever, I'm just explaining why it isn't added at the moment.