error[E0277]: the trait bound `No: CanSplitInto<Mut, No>` is not satisfied
  --> $DIR/autobad-split-no-mut-no.rs:16:41
   |
16 |               &mut partial!(X ! a)) = i.into();
   |                                         ^^^^ the trait `CanSplitInto<Mut, No>` is not implemented for `No`
   |
   = help: the trait `CanSplitInto<No, No>` is implemented for `No`
note: required because of the requirements on the impl of `From<&mut X__Partial<No>>` for `(&mut X__Partial<Mut>, &mut X__Partial<No>)`
  --> $DIR/autobad-split-no-mut-no.rs:9:10
   |
9  | #[derive(PartialBorrow,Default)]
   |          ^^^^^^^^^^^^^
   = note: required because of the requirements on the impl of `Into<(&mut X__Partial<Mut>, &mut X__Partial<No>)>` for `&mut X__Partial<No>`
   = note: this error originates in the derive macro `PartialBorrow` (in Nightly builds, run with -Z macro-backtrace for more info)