Macro dyn_maybe_sync

macro_rules! dyn_maybe_sync {
    ($($traits:tt)+) => { ... };
}

Expands to dyn $traits with Sync marker trait added when “sync” feature is enabled.

Expands to dyn $traits without Sync marker trait added “sync” feature is not enabled.

Example

fn foo<T: MaybeSync + ?Sized>(_: &T) {}
// `x` will implement `MaybeSync` whether "sync" feature is enabled or not.
let x: &dyn_maybe_sync!(AsRef<str>) = &"qwerty";
foo(x);