yeah, that's actually why i think i wanted the ability to set it on a per-target basis, to accomodate switching over e.g. source. i think there should be some way to make the gradual switchover to

'warn'

easier, but i'm not sure what the interface should be

The two ways I've seen this work before are: 1. Have a default in pants.ini. Have a function you can call to override the default for a file. Add the override to 'ignore' to every BUILD file, set the default to warn/error, start removing the override calls incrementally. 2. Have a pants.ini config list of prefix -> config value, carve out prefixes as needed