Enum Witness 

pub enum Witness {
    Default,
    Function(*const c_void),
    Metadata(*const c_void),
}

What to put in one slot of a witness table.

Variants

Default

Use the default implementation the protocol descriptor records.

Panics

At build time, if the requirement has no default.

Function(*const c_void)

A function implementing the requirement.

Metadata(*const c_void)

Metadata for an associated type, stored directly.

This is the form to use. SwiftUI’s own tables instead hold a pointer to a mangled name with bit 0 set — the runtime accepts either — but a name written here fails to demangle, because the blob the runtime expects is not a plain string: it carries symbolic references, which are relative pointers into the emitting image. Metadata needs no such context.

Trait Implementations

impl Clone for Witness

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Witness