The clean provider of the thrift namespace: deletes every generator-owned file (.erl/.hrl carrying the Autogenerated by Thrift Generator banner) from the configured out dir.

Not meant for the command line: a default-namespace provider wins rebar3's resolution, so rebar3 thrift clean is answered by the main thrift provider. This one exists to be hooked into the project clean — the consumer's rebar.config:

{provider_hooks, [{post, [{clean, {thrift, clean}}]}]}