If you load the dest schema into mysql, the upgrade SQL presented does not work. If task_role does not exist first, the problem goes away. Tested on MySQL Ver 5.0.51a-24+lenny5

enum-to-foreign-key-bug.pl

#! /usr/bin/perl
use strict;
use warnings;
use SQL::Translator;
use SQL::Translator::Diff;
use Data::Dumper;
$Data::Dumper::Indent = 1;


my $dest_schema = get_schema(q{
DROP TABLE IF EXISTS `task`;
CREATE TABLE `task` (
  `id` int(11) NOT NULL auto_increment,
  `type` varchar(255) NOT NULL,
  `role` enum('primary','secondary','tertiary') NOT NULL default 'primary',
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `task_role`;
CREATE TABLE `task_role` (
  `id` int(11) NOT NULL auto_increment,
  `name` varchar(255) character set latin1 NOT NULL,
  PRIMARY KEY  (`id`),
  UNIQUE KEY `name` (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
});

my $source_schema = get_schema(q{
CREATE TABLE `task` (
  `id` integer NOT NULL auto_increment,
  `role` varchar(255) NOT NULL,
  INDEX `task_idx_role` (`role`),
  PRIMARY KEY (`id`),
  CONSTRAINT `task_fk_role` FOREIGN KEY (`role`) REFERENCES `task_role` (`name`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARACTER SET utf8;

CREATE TABLE `task_role` (
  `id` integer NOT NULL auto_increment,
  `name` varchar(255) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE `name` (`name`)
) ENGINE=InnoDB DEFAULT CHARACTER SET utf8;
});

my $diff = SQL::Translator::Diff::schema_diff(
    $dest_schema, 'MySQL', $source_schema, 'MySQL');

print $diff;

sub get_schema {
    my $data = shift;

    my $t = SQL::Translator->new();
    $t->parser('MySQL');

    my $out = $t->translate(\$data)
      or die $t->error;
    return $t->schema();
}