src/test/ui/traits/object/safety.stderr

   1 error[E0038]: the trait `Tr` cannot be made into an object
   2   --> $DIR/safety.rs:15:22
   3    |
   4 LL |     let _: &dyn Tr = &St;
   5    |                      ^^^ `Tr` cannot be made into an object
   6    |
   7 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>
   8   --> $DIR/safety.rs:4:8
   9    |
  10 LL | trait Tr {
  11    |       -- this trait cannot be made into an object...
  12 LL |     fn foo();
  13    |        ^^^ ...because associated function `foo` has no `self` parameter
  14    = note: required for `&St` to implement `CoerceUnsized<&dyn Tr>`
  15    = note: required by cast to type `&dyn Tr`
  16 help: consider turning `foo` into a method by giving it a `&self` argument
  17    |
  18 LL |     fn foo(&self);
  19    |            +++++
  20 help: alternatively, consider constraining `foo` so it does not apply to trait objects
  21    |
  22 LL |     fn foo() where Self: Sized;
  23    |              +++++++++++++++++
  24
  25 error[E0038]: the trait `Tr` cannot be made into an object
  26   --> $DIR/safety.rs:15:12
  27    |
  28 LL |     let _: &dyn Tr = &St;
  29    |            ^^^^^^^ `Tr` cannot be made into an object
  30    |
  31 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>
  32   --> $DIR/safety.rs:4:8
  33    |
  34 LL | trait Tr {
  35    |       -- this trait cannot be made into an object...
  36 LL |     fn foo();
  37    |        ^^^ ...because associated function `foo` has no `self` parameter
  38 help: consider turning `foo` into a method by giving it a `&self` argument
  39    |
  40 LL |     fn foo(&self);
  41    |            +++++
  42 help: alternatively, consider constraining `foo` so it does not apply to trait objects
  43    |
  44 LL |     fn foo() where Self: Sized;
  45    |              +++++++++++++++++
  46
  47 error: aborting due to 2 previous errors
  48
  49 For more information about this error, try `rustc --explain E0038`.