Required drush version limited to 8

Same here.

Added patch which reverts eb81dde707ed84a0b20487caa1d5239ec02721e4.

Seems like drush 9 is not supported ATM: https://www.drupal.org/project/gdpr/issues/2931820#comment-12457275 > 4.

@mhavelant, drush 9 is default in new D8 projects nowadays and gdpr 8.x-1.0-alpha8 worked well in drush 9 environment. Could we cut the drush gdpr-sql-dump part into separate module and remove "drush/drush": "~8" dependency from 8.x-1.x-dev?

A ‘softer’ option might be to remove the dependency, but add a check to hook_requirements in the dump module that flags up a conflict with drush 9?

None of the project actually depends on drush, the gdpr_dump module is just a bit toothless without it. So it doesn’t necessarily need to be a true ‘requirement’.

Another option could be to change the drush 8 requirement into a composer ‘conflicts’ statement for drush 9. So it still wouldn’t allow installing them together, but also allows people to install the GDPR project without needing drush (eg for those using it without the dump submodule).

The ideal would be to sort out the drush 8 requirement though so that it could actually work with drush 9 :-) I think there was mention of how commands can be made to work for both, on the original drush ticket for this project?

Discussion of supporting drush 9 as well as drush 8 was in #2940033: Simplify D8 development by keeping single version branch. A way forward is needed somehow - personally, I think even if it means some duplicate code. The two commands both just call through to services, so I don't think much/any duplicate code is needed anyway, we can just do it exactly like config_split (http://nuvole.org/blog/2017/oct/13/how-maintain-drush-commands-drush-8-a...) does.

Removed the drush 8 restriction from composer, added a hook_requirement info entry to notify about dump needing Drush 8.

As per the "Support both Drush 8 and 9 at the same time" debate, I tried to make it work but due to the module extending the Drush Sql classes (that needed the least amount of custom code) it would lead to a pretty complex codebase, which would not be great. That's the reason 8.x-2.x has been created so we have a separate place for Drush 9 support, but since most of the D8 sites probably are still using v8, it has been sidelined.

Note: I synced the 8.x-2.x with 1.x, they should be completely identical except for the GDPR Dump module.
If anyone wants to port the module from 1.x, feel free to do it, 2.x already has some skeleton classes.