ices/76535.rs: fixed with errors

[github-actions]

Issue: rust-lang/rust#76535

#![feature(generic_associated_types)]

pub trait SubTrait {}

pub trait SuperTrait {
    type SubType<'a>: SubTrait;

    fn get_sub<'a>(&'a mut self) -> Self::SubType<'a>;
}

pub struct SubStruct<'a> {
    sup: &'a mut SuperStruct,
}

impl<'a> SubTrait for SubStruct<'a> {}

pub struct SuperStruct {
    value: u8,
}

impl SuperStruct {
    pub fn new(value: u8) -> SuperStruct {
        SuperStruct { value }
    }
}

impl SuperTrait for SuperStruct {
    type SubType<'a> = SubStruct<'a>;

    fn get_sub<'a>(&'a mut self) -> Self::SubType<'a> {
        SubStruct { sup: self }
    }
}

fn main() {
    let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
}

=== stdout ===
=== stderr ===
warning: the feature `generic_associated_types` is incomplete and may not be safe to use and/or cause compiler crashes
 --> /home/runner/work/glacier/glacier/ices/76535.rs:1:12
  |
1 | #![feature(generic_associated_types)]
  |            ^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(incomplete_features)]` on by default
  = note: see issue #44265 <https://github.com/rust-lang/rust/issues/44265> for more information

error[E0107]: missing generics for associated type `SuperTrait::SubType`
 --> /home/runner/work/glacier/glacier/ices/76535.rs:6:10
  |
6 |     type SubType<'a>: SubTrait;
  |          ^^^^^^^ expected 1 lifetime argument
  |
note: associated type defined here, with 1 lifetime parameter: `'a`
 --> /home/runner/work/glacier/glacier/ices/76535.rs:6:10
  |
6 |     type SubType<'a>: SubTrait;
  |          ^^^^^^^ --
help: use angle brackets to add missing lifetime argument
  |
6 |     type SubType<'a><'a>: SubTrait;
  |                 ^^^^

error[E0038]: the trait `SuperTrait` cannot be made into an object
  --> /home/runner/work/glacier/glacier/ices/76535.rs:36:14
   |
36 |     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SuperTrait` cannot be made into an object
   |
   = help: consider moving `get_sub` to another trait
note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
  --> /home/runner/work/glacier/glacier/ices/76535.rs:8:37
   |
5  | pub trait SuperTrait {
   |           ---------- this trait cannot be made into an object...
...
8  |     fn get_sub<'a>(&'a mut self) -> Self::SubType<'a>;
   |                                     ^^^^^^^^^^^^^^^^^ ...because method `get_sub` references the `Self` type in its return type

error[E0038]: the trait `SuperTrait` cannot be made into an object
  --> /home/runner/work/glacier/glacier/ices/76535.rs:36:57
   |
36 |     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
   |                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SuperTrait` cannot be made into an object
   |
   = help: consider moving `get_sub` to another trait
note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
  --> /home/runner/work/glacier/glacier/ices/76535.rs:8:37
   |
5  | pub trait SuperTrait {
   |           ---------- this trait cannot be made into an object...
...
8  |     fn get_sub<'a>(&'a mut self) -> Self::SubType<'a>;
   |                                     ^^^^^^^^^^^^^^^^^ ...because method `get_sub` references the `Self` type in its return type
   = note: required because of the requirements on the impl of `CoerceUnsized<Box<dyn SuperTrait<SubType = SubStruct<'_>>>>` for `Box<SuperStruct>`
   = note: required by cast to type `Box<dyn SuperTrait<SubType = SubStruct<'_>>>`

error: aborting due to 3 previous errors; 1 warning emitted

Some errors have detailed explanations: E0038, E0107.
For more information about an error, try `rustc --explain E0038`.
==============