mirror of
https://github.com/rust-lang/rust.git
synced 2025-10-04 19:28:29 +00:00
3ef9d4d0ed
By default, `newtype_index!` types get a default `Encodable`/`Decodable` impl. You can opt out of this with `custom_encodable`. Opting out is the opposite to how Rust normally works with autogenerated (derived) impls. This commit inverts the behaviour, replacing `custom_encodable` with `encodable` which opts into the default `Encodable`/`Decodable` impl. Only 23 of the 59 `newtype_index!` occurrences need `encodable`. Even better, there were eight crates with a dependency on `rustc_serialize` just from unused default `Encodable`/`Decodable` impls. This commit removes that dependency from those eight crates.
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.