src/test/ui/generic-associated-types/issue-76535.stderr

   1 error[E0107]: missing generics for associated type `SuperTrait::SubType`
   2   --> $DIR/issue-76535.rs:36:33
   3    |
   4 LL |     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
   5    |                                 ^^^^^^^ expected 1 lifetime argument
   6    |
   7 note: associated type defined here, with 1 lifetime parameter: `'a`
   8   --> $DIR/issue-76535.rs:6:10
   9    |
  10 LL |     type SubType<'a>: SubTrait where Self: 'a;
  11    |          ^^^^^^^ --
  12 help: add missing lifetime argument
  13    |
  14 LL |     let sub: Box<dyn SuperTrait<SubType<'a> = SubStruct>> = Box::new(SuperStruct::new(0));
  15    |                                 ~~~~~~~~~~~
  16
  17 error[E0038]: the trait `SuperTrait` cannot be made into an object
  18   --> $DIR/issue-76535.rs:36:14
  19    |
  20 LL |     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
  21    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SuperTrait` cannot be made into an object
  22    |
  23 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>
  24   --> $DIR/issue-76535.rs:6:10
  25    |
  26 LL | pub trait SuperTrait {
  27    |           ---------- this trait cannot be made into an object...
  28 LL |     type SubType<'a>: SubTrait where Self: 'a;
  29    |          ^^^^^^^ ...because it contains the generic associated type `SubType`
  30    = help: consider moving `SubType` to another trait
  31
  32 error[E0038]: the trait `SuperTrait` cannot be made into an object
  33   --> $DIR/issue-76535.rs:36:57
  34    |
  35 LL |     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
  36    |                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SuperTrait` cannot be made into an object
  37    |
  38 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>
  39   --> $DIR/issue-76535.rs:6:10
  40    |
  41 LL | pub trait SuperTrait {
  42    |           ---------- this trait cannot be made into an object...
  43 LL |     type SubType<'a>: SubTrait where Self: 'a;
  44    |          ^^^^^^^ ...because it contains the generic associated type `SubType`
  45    = help: consider moving `SubType` to another trait
  46    = note: required because of the requirements on the impl of `CoerceUnsized<Box<dyn SuperTrait<SubType = SubStruct<'_>>>>` for `Box<SuperStruct>`
  47    = note: required by cast to type `Box<dyn SuperTrait<SubType = SubStruct<'_>>>`
  48
  49 error: aborting due to 3 previous errors
  50
  51 Some errors have detailed explanations: E0038, E0107.
  52 For more information about an error, try `rustc --explain E0038`.