error[E0038]: the trait `FromResidual` cannot be made into an object --> $DIR/canonicalize-fresh-infer-vars-issue-103626.rs:10:17 | LL | let b: &dyn FromResidual = &(); | ^^^^^^^^^^^^ | = note: it cannot use `Self` as a type parameter in a supertrait or `where`-clause error[E0038]: the trait `FromResidual` cannot be made into an object --> $DIR/canonicalize-fresh-infer-vars-issue-103626.rs:10:12 | LL | let b: &dyn FromResidual = &(); | ^^^^^^^^^^^^^^^^^ `FromResidual` cannot be made into an object | 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 --> $DIR/canonicalize-fresh-infer-vars-issue-103626.rs:2:8 | LL | trait FromResidual::Residual> { | ------------ this trait cannot be made into an object... LL | fn from_residual(residual: R) -> Self; | ^^^^^^^^^^^^^ ...because associated function `from_residual` has no `self` parameter help: consider turning `from_residual` into a method by giving it a `&self` argument | LL | fn from_residual(&self, residual: R) -> Self; | ++++++ help: alternatively, consider constraining `from_residual` so it does not apply to trait objects | LL | fn from_residual(residual: R) -> Self where Self: Sized; | +++++++++++++++++ error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0038`.