Module rustc_trait_selection::traits::object_safety

“Object safety” refers to the ability for a trait to be converted to an object. In general, traits may only be converted to an object if all of their methods meet certain criteria. In particular, they must:

• have a suitable receiver from which we can extract a vtable and coerce to a “thin” version that doesn’t contain the vtable;
• not reference the erased type Self except for in this receiver;
• not have generic type parameters.

Enums

• MethodViolationCode
  Reasons a method might not be object-safe.
• ObjectSafetyViolation

Functions

• astconv_object_safety_violations
  Returns the object safety violations that affect astconv – currently, Self in supertraits. This is needed because object_safety_violations can’t be used during type collection.
• bounds_reference_self 🔒
• check_is_object_safe 🔒
• contains_illegal_impl_trait_in_trait
• contains_illegal_self_type_reference 🔒
• generics_require_sized_self 🔒
• get_sized_bounds 🔒
• is_vtable_safe_method
  We say a method is vtable safe if it can be invoked on a trait object. Note that object-safe traits can have some non-vtable-safe methods, so long as they require Self: Sized or otherwise ensure that they cannot be used when Self = Trait.
• lint_object_unsafe_trait 🔒
  Lint object-unsafe trait.
• object_safety_violations 🔒
• object_safety_violations_for_assoc_item
  Returns Some(_) if this item makes the containing trait not object safe.
• object_safety_violations_for_trait 🔒
• object_ty_for_trait 🔒
  Creates the object type for the current trait. For example, if the current trait is Deref, then this will be dyn Deref<Target = Self::Target> + 'static.
• predicate_references_self 🔒
• predicates_reference_self 🔒
• provide
• receiver_for_self_ty 🔒
  Performs a type instantiation to produce the version of receiver_ty when Self = self_ty. For example, for receiver_ty = Rc<Self> and self_ty = Foo, returns Rc<Foo>.
• receiver_is_dispatchable 🔒
  Checks the method’s receiver (the self argument) can be dispatched on when Self is a trait object. We require that DispatchableFromDyn be implemented for the receiver type in the following way:
• sized_trait_bound_spans 🔒
• super_predicates_have_non_lifetime_binders 🔒
• trait_has_sized_self 🔒
• virtual_call_violations_for_method 🔒
  Returns Some(_) if this method cannot be called on a trait object; this does not necessarily imply that the enclosing trait is not object safe, because the method might have a where clause Self:Sized.