How to fix the «Command line user may not have proper read+execute permissions for directories under "var/generation/"» issue?

[dmitry_fedyuk (Dmitrii Fediuk)]

Part 1

The var/generation directory shoud:

• be present (the requirement is a bug, because the var/generation directory is autogenerated)
• be readable
• be executable

Part 2

If you are on Windows, you need an additional patch.

[dmitry_fedyuk (Dmitrii Fediuk)]

See also:

• Bug: the console commands fail with the message «Command line user may not have proper read+execute permissions for directories under “var/generation/”» when the «var/generation» directory is absent
• Bug: \Magento\Framework\Setup\FilePermissions::checkDirectoryPermissionForCLIUser() fails on Windows (wrongly detects whether a directory is executable)
• How to fix the «Command line user does not have read and write permissions on var/generation directory» issue?