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.

Structs

• EraseEscapingBoundRegions 🔒
• IllegalSelfTypeVisitor 🔒

Enums

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

Functions

• bounds_reference_self 🔒
• check_receiver_correct
  This code checks that receiver_is_dispatchable is correctly implemented.
• contains_illegal_impl_trait_in_trait
• contains_illegal_self_type_reference 🔒
  This is somewhat subtle. In general, we want to forbid references to Self in the argument and return types, since the value of Self is erased. However, there is one exception: it is ok to reference Self in order to access an associated type of the current trait, since we retain the value of those associated types in the object type itself.
• generics_require_sized_self 🔒
• get_sized_bounds 🔒
• hir_ty_lowering_object_safety_violations
  Returns the object safety violations that affect HIR ty lowering.
• is_object_safe 🔒
• 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.
• 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.