Nilstrieb d679764fb6 Make #[debug_format] an attribute in newtype_index
This removes the `custom` format functionality as its only user was
trivially migrated to using a normal format.

If a new use case for a custom formatting impl pops up, you can add it
back.
2022-12-18 21:37:38 +01:00
..
2022-09-29 16:49:04 +09:00