When using a service alias, a parameter in case of the alias name can NOT be used. Exceptions: 'InvalidArgumentException: Unable to replace alias "%my_alias%" with "bar".' 'InvalidArgumentException: The service definition "%my_alias%" does not exist.'

services.yml

parameters:
   my_alias: foo

services:
   foo:
     class: Example\Foo
   bar:
     alias: %my_alias%

#--------------------------------------------

# For clarification, a real life example:
# fos_user.repository.user would be a service from a different bundle.
# Via parameter the used service should be abled to change.

parameters:
   my_bundle.repository.user.alias: fos_user.repository.user

services:
   my_bundle.repository.user:
      alias: %my_bundle.repository.user.alias%