downcast_rs/lib.rs
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#![deny(unsafe_code,rustdoc::bare_urls)]
#![cfg_attr(not(feature = "std"), no_std)]
//! [](https://github.com/marcianx/downcast-rs/actions)
//! [](https://crates.io/crates/downcast-rs)
//! [](https://docs.rs/downcast-rs)
//!
//! Rust enums are great for types where all variations are known beforehand. But a
//! container of user-defined types requires an open-ended type like a **trait
//! object**. Some applications may want to cast these trait objects back to the
//! original concrete types to access additional functionality and performant
//! inlined implementations.
//!
//! `downcast-rs` adds this downcasting support to trait objects using only safe
//! Rust. It supports **type parameters**, **associated types**, and **constraints**.
//!
//! # Usage
//!
//! Add the following to your `Cargo.toml`:
//!
//! ```toml
//! [dependencies]
//! downcast-rs = "1.2.1"
//! ```
//!
//! This crate is `no_std` compatible. To use it without `std`:
//!
//! ```toml
//! [dependencies]
//! downcast-rs = { version = "1.2.0", default-features = false }
//! ```
//!
//! To make a trait downcastable, make it extend either `downcast::Downcast` or
//! `downcast::DowncastSync` and invoke `impl_downcast!` on it as in the examples
//! below.
//!
//! Since 1.2.0, the minimum supported Rust version is 1.36 due to needing stable access to alloc.
//!
//! ```
//! # #[macro_use]
//! # extern crate downcast_rs;
//! # use downcast_rs::{Downcast, DowncastSync};
//! trait Trait: Downcast {}
//! impl_downcast!(Trait);
//!
//! // Also supports downcasting `Arc`-ed trait objects by extending `DowncastSync`
//! // and starting `impl_downcast!` with `sync`.
//! trait TraitSync: DowncastSync {}
//! impl_downcast!(sync TraitSync);
//!
//! // With type parameters.
//! trait TraitGeneric1<T>: Downcast {}
//! impl_downcast!(TraitGeneric1<T>);
//!
//! // With associated types.
//! trait TraitGeneric2: Downcast { type G; type H; }
//! impl_downcast!(TraitGeneric2 assoc G, H);
//!
//! // With constraints on types.
//! trait TraitGeneric3<T: Copy>: Downcast {
//! type H: Clone;
//! }
//! impl_downcast!(TraitGeneric3<T> assoc H where T: Copy, H: Clone);
//!
//! // With concrete types.
//! trait TraitConcrete1<T: Copy>: Downcast {}
//! impl_downcast!(concrete TraitConcrete1<u32>);
//!
//! trait TraitConcrete2<T: Copy>: Downcast { type H; }
//! impl_downcast!(concrete TraitConcrete2<u32> assoc H=f64);
//! # fn main() {}
//! ```
//!
//! # Example without generics
//!
//! ```
//! # use std::rc::Rc;
//! # use std::sync::Arc;
//! // Import macro via `macro_use` pre-1.30.
//! #[macro_use]
//! extern crate downcast_rs;
//! use downcast_rs::DowncastSync;
//!
//! // To create a trait with downcasting methods, extend `Downcast` or `DowncastSync`
//! // and run `impl_downcast!()` on the trait.
//! trait Base: DowncastSync {}
//! impl_downcast!(sync Base); // `sync` => also produce `Arc` downcasts.
//!
//! // Concrete types implementing Base.
//! #[derive(Debug)]
//! struct Foo(u32);
//! impl Base for Foo {}
//! #[derive(Debug)]
//! struct Bar(f64);
//! impl Base for Bar {}
//!
//! fn main() {
//! // Create a trait object.
//! let mut base: Box<Base> = Box::new(Foo(42));
//!
//! // Try sequential downcasts.
//! if let Some(foo) = base.downcast_ref::<Foo>() {
//! assert_eq!(foo.0, 42);
//! } else if let Some(bar) = base.downcast_ref::<Bar>() {
//! assert_eq!(bar.0, 42.0);
//! }
//!
//! assert!(base.is::<Foo>());
//!
//! // Fail to convert `Box<Base>` into `Box<Bar>`.
//! let res = base.downcast::<Bar>();
//! assert!(res.is_err());
//! let base = res.unwrap_err();
//! // Convert `Box<Base>` into `Box<Foo>`.
//! assert_eq!(42, base.downcast::<Foo>().map_err(|_| "Shouldn't happen.").unwrap().0);
//!
//! // Also works with `Rc`.
//! let mut rc: Rc<Base> = Rc::new(Foo(42));
//! assert_eq!(42, rc.downcast_rc::<Foo>().map_err(|_| "Shouldn't happen.").unwrap().0);
//!
//! // Since this trait is `Sync`, it also supports `Arc` downcasts.
//! let mut arc: Arc<Base> = Arc::new(Foo(42));
//! assert_eq!(42, arc.downcast_arc::<Foo>().map_err(|_| "Shouldn't happen.").unwrap().0);
//! }
//! ```
//!
//! # Example with a generic trait with associated types and constraints
//!
//! ```
//! // Can call macro via namespace since rust 1.30.
//! extern crate downcast_rs;
//! use downcast_rs::Downcast;
//!
//! // To create a trait with downcasting methods, extend `Downcast` or `DowncastSync`
//! // and run `impl_downcast!()` on the trait.
//! trait Base<T: Clone>: Downcast { type H: Copy; }
//! downcast_rs::impl_downcast!(Base<T> assoc H where T: Clone, H: Copy);
//! // or: impl_downcast!(concrete Base<u32> assoc H=f32)
//!
//! // Concrete types implementing Base.
//! struct Foo(u32);
//! impl Base<u32> for Foo { type H = f32; }
//! struct Bar(f64);
//! impl Base<u32> for Bar { type H = f32; }
//!
//! fn main() {
//! // Create a trait object.
//! let mut base: Box<Base<u32, H=f32>> = Box::new(Bar(42.0));
//!
//! // Try sequential downcasts.
//! if let Some(foo) = base.downcast_ref::<Foo>() {
//! assert_eq!(foo.0, 42);
//! } else if let Some(bar) = base.downcast_ref::<Bar>() {
//! assert_eq!(bar.0, 42.0);
//! }
//!
//! assert!(base.is::<Bar>());
//! }
//! ```
// for compatibility with no std and macros
#[doc(hidden)]
#[cfg(not(feature = "std"))]
pub extern crate core as __std;
#[doc(hidden)]
#[cfg(feature = "std")]
pub extern crate std as __std;
#[doc(hidden)]
pub extern crate alloc as __alloc;
use __std::any::Any;
use __alloc::{boxed::Box, rc::Rc, sync::Arc};
/// Supports conversion to `Any`. Traits to be extended by `impl_downcast!` must extend `Downcast`.
pub trait Downcast: Any {
/// Convert `Box<dyn Trait>` (where `Trait: Downcast`) to `Box<dyn Any>`. `Box<dyn Any>` can
/// then be further `downcast` into `Box<ConcreteType>` where `ConcreteType` implements `Trait`.
fn into_any(self: Box<Self>) -> Box<dyn Any>;
/// Convert `Rc<Trait>` (where `Trait: Downcast`) to `Rc<Any>`. `Rc<Any>` can then be
/// further `downcast` into `Rc<ConcreteType>` where `ConcreteType` implements `Trait`.
fn into_any_rc(self: Rc<Self>) -> Rc<dyn Any>;
/// Convert `&Trait` (where `Trait: Downcast`) to `&Any`. This is needed since Rust cannot
/// generate `&Any`'s vtable from `&Trait`'s.
fn as_any(&self) -> &dyn Any;
/// Convert `&mut Trait` (where `Trait: Downcast`) to `&Any`. This is needed since Rust cannot
/// generate `&mut Any`'s vtable from `&mut Trait`'s.
fn as_any_mut(&mut self) -> &mut dyn Any;
}
impl<T: Any> Downcast for T {
fn into_any(self: Box<Self>) -> Box<dyn Any> { self }
fn into_any_rc(self: Rc<Self>) -> Rc<dyn Any> { self }
fn as_any(&self) -> &dyn Any { self }
fn as_any_mut(&mut self) -> &mut dyn Any { self }
}
/// Extends `Downcast` to support `Sync` traits that thus support `Arc` downcasting as well.
pub trait DowncastSync: Downcast + Send + Sync {
/// Convert `Arc<Trait>` (where `Trait: Downcast`) to `Arc<Any>`. `Arc<Any>` can then be
/// further `downcast` into `Arc<ConcreteType>` where `ConcreteType` implements `Trait`.
fn into_any_arc(self: Arc<Self>) -> Arc<dyn Any + Send + Sync>;
}
impl<T: Any + Send + Sync> DowncastSync for T {
fn into_any_arc(self: Arc<Self>) -> Arc<dyn Any + Send + Sync> { self }
}
/// Adds downcasting support to traits that extend `downcast::Downcast` by defining forwarding
/// methods to the corresponding implementations on `std::any::Any` in the standard library.
///
/// See <https://users.rust-lang.org/t/how-to-create-a-macro-to-impl-a-provided-type-parametrized-trait/5289>
/// for why this is implemented this way to support templatized traits.
#[macro_export(local_inner_macros)]
macro_rules! impl_downcast {
(@impl_full
$trait_:ident [$($param_types:tt)*]
for [$($forall_types:ident),*]
where [$($preds:tt)*]
) => {
impl_downcast! {
@inject_where
[impl<$($forall_types),*> dyn $trait_<$($param_types)*>]
types [$($forall_types),*]
where [$($preds)*]
[{
impl_downcast! { @impl_body $trait_ [$($param_types)*] }
}]
}
};
(@impl_full_sync
$trait_:ident [$($param_types:tt)*]
for [$($forall_types:ident),*]
where [$($preds:tt)*]
) => {
impl_downcast! {
@inject_where
[impl<$($forall_types),*> dyn $trait_<$($param_types)*>]
types [$($forall_types),*]
where [$($preds)*]
[{
impl_downcast! { @impl_body $trait_ [$($param_types)*] }
impl_downcast! { @impl_body_sync $trait_ [$($param_types)*] }
}]
}
};
(@impl_body $trait_:ident [$($types:tt)*]) => {
/// Returns true if the trait object wraps an object of type `__T`.
#[inline]
pub fn is<__T: $trait_<$($types)*>>(&self) -> bool {
$crate::Downcast::as_any(self).is::<__T>()
}
/// Returns a boxed object from a boxed trait object if the underlying object is of type
/// `__T`. Returns the original boxed trait if it isn't.
#[inline]
pub fn downcast<__T: $trait_<$($types)*>>(
self: $crate::__alloc::boxed::Box<Self>
) -> $crate::__std::result::Result<$crate::__alloc::boxed::Box<__T>, $crate::__alloc::boxed::Box<Self>> {
if self.is::<__T>() {
Ok($crate::Downcast::into_any(self).downcast::<__T>().unwrap())
} else {
Err(self)
}
}
/// Returns an `Rc`-ed object from an `Rc`-ed trait object if the underlying object is of
/// type `__T`. Returns the original `Rc`-ed trait if it isn't.
#[inline]
pub fn downcast_rc<__T: $trait_<$($types)*>>(
self: $crate::__alloc::rc::Rc<Self>
) -> $crate::__std::result::Result<$crate::__alloc::rc::Rc<__T>, $crate::__alloc::rc::Rc<Self>> {
if self.is::<__T>() {
Ok($crate::Downcast::into_any_rc(self).downcast::<__T>().unwrap())
} else {
Err(self)
}
}
/// Returns a reference to the object within the trait object if it is of type `__T`, or
/// `None` if it isn't.
#[inline]
pub fn downcast_ref<__T: $trait_<$($types)*>>(&self) -> $crate::__std::option::Option<&__T> {
$crate::Downcast::as_any(self).downcast_ref::<__T>()
}
/// Returns a mutable reference to the object within the trait object if it is of type
/// `__T`, or `None` if it isn't.
#[inline]
pub fn downcast_mut<__T: $trait_<$($types)*>>(&mut self) -> $crate::__std::option::Option<&mut __T> {
$crate::Downcast::as_any_mut(self).downcast_mut::<__T>()
}
};
(@impl_body_sync $trait_:ident [$($types:tt)*]) => {
/// Returns an `Arc`-ed object from an `Arc`-ed trait object if the underlying object is of
/// type `__T`. Returns the original `Arc`-ed trait if it isn't.
#[inline]
pub fn downcast_arc<__T: $trait_<$($types)*> + $crate::__std::any::Any + $crate::__std::marker::Send + $crate::__std::marker::Sync>(
self: $crate::__alloc::sync::Arc<Self>,
) -> $crate::__std::result::Result<$crate::__alloc::sync::Arc<__T>, $crate::__alloc::sync::Arc<Self>>
{
if self.is::<__T>() {
Ok($crate::DowncastSync::into_any_arc(self).downcast::<__T>().unwrap())
} else {
Err(self)
}
}
};
(@inject_where [$($before:tt)*] types [] where [] [$($after:tt)*]) => {
impl_downcast! { @as_item $($before)* $($after)* }
};
(@inject_where [$($before:tt)*] types [$($types:ident),*] where [] [$($after:tt)*]) => {
impl_downcast! {
@as_item
$($before)*
where $( $types: $crate::__std::any::Any + 'static ),*
$($after)*
}
};
(@inject_where [$($before:tt)*] types [$($types:ident),*] where [$($preds:tt)+] [$($after:tt)*]) => {
impl_downcast! {
@as_item
$($before)*
where
$( $types: $crate::__std::any::Any + 'static, )*
$($preds)*
$($after)*
}
};
(@as_item $i:item) => { $i };
// No type parameters.
($trait_:ident ) => { impl_downcast! { @impl_full $trait_ [] for [] where [] } };
($trait_:ident <>) => { impl_downcast! { @impl_full $trait_ [] for [] where [] } };
(sync $trait_:ident ) => { impl_downcast! { @impl_full_sync $trait_ [] for [] where [] } };
(sync $trait_:ident <>) => { impl_downcast! { @impl_full_sync $trait_ [] for [] where [] } };
// Type parameters.
($trait_:ident < $($types:ident),* >) => {
impl_downcast! { @impl_full $trait_ [$($types),*] for [$($types),*] where [] }
};
(sync $trait_:ident < $($types:ident),* >) => {
impl_downcast! { @impl_full_sync $trait_ [$($types),*] for [$($types),*] where [] }
};
// Type parameters and where clauses.
($trait_:ident < $($types:ident),* > where $($preds:tt)+) => {
impl_downcast! { @impl_full $trait_ [$($types),*] for [$($types),*] where [$($preds)*] }
};
(sync $trait_:ident < $($types:ident),* > where $($preds:tt)+) => {
impl_downcast! { @impl_full_sync $trait_ [$($types),*] for [$($types),*] where [$($preds)*] }
};
// Associated types.
($trait_:ident assoc $($atypes:ident),*) => {
impl_downcast! { @impl_full $trait_ [$($atypes = $atypes),*] for [$($atypes),*] where [] }
};
(sync $trait_:ident assoc $($atypes:ident),*) => {
impl_downcast! { @impl_full_sync $trait_ [$($atypes = $atypes),*] for [$($atypes),*] where [] }
};
// Associated types and where clauses.
($trait_:ident assoc $($atypes:ident),* where $($preds:tt)+) => {
impl_downcast! { @impl_full $trait_ [$($atypes = $atypes),*] for [$($atypes),*] where [$($preds)*] }
};
(sync $trait_:ident assoc $($atypes:ident),* where $($preds:tt)+) => {
impl_downcast! { @impl_full_sync $trait_ [$($atypes = $atypes),*] for [$($atypes),*] where [$($preds)*] }
};
// Type parameters and associated types.
($trait_:ident < $($types:ident),* > assoc $($atypes:ident),*) => {
impl_downcast! {
@impl_full
$trait_ [$($types),*, $($atypes = $atypes),*]
for [$($types),*, $($atypes),*]
where []
}
};
(sync $trait_:ident < $($types:ident),* > assoc $($atypes:ident),*) => {
impl_downcast! {
@impl_full_sync
$trait_ [$($types),*, $($atypes = $atypes),*]
for [$($types),*, $($atypes),*]
where []
}
};
// Type parameters, associated types, and where clauses.
($trait_:ident < $($types:ident),* > assoc $($atypes:ident),* where $($preds:tt)+) => {
impl_downcast! {
@impl_full
$trait_ [$($types),*, $($atypes = $atypes),*]
for [$($types),*, $($atypes),*]
where [$($preds)*]
}
};
(sync $trait_:ident < $($types:ident),* > assoc $($atypes:ident),* where $($preds:tt)+) => {
impl_downcast! {
@impl_full_sync
$trait_ [$($types),*, $($atypes = $atypes),*]
for [$($types),*, $($atypes),*]
where [$($preds)*]
}
};
// Concretely-parametrized types.
(concrete $trait_:ident < $($types:ident),* >) => {
impl_downcast! { @impl_full $trait_ [$($types),*] for [] where [] }
};
(sync concrete $trait_:ident < $($types:ident),* >) => {
impl_downcast! { @impl_full_sync $trait_ [$($types),*] for [] where [] }
};
// Concretely-associated types types.
(concrete $trait_:ident assoc $($atypes:ident = $aty:ty),*) => {
impl_downcast! { @impl_full $trait_ [$($atypes = $aty),*] for [] where [] }
};
(sync concrete $trait_:ident assoc $($atypes:ident = $aty:ty),*) => {
impl_downcast! { @impl_full_sync $trait_ [$($atypes = $aty),*] for [] where [] }
};
// Concretely-parametrized types with concrete associated types.
(concrete $trait_:ident < $($types:ident),* > assoc $($atypes:ident = $aty:ty),*) => {
impl_downcast! { @impl_full $trait_ [$($types),*, $($atypes = $aty),*] for [] where [] }
};
(sync concrete $trait_:ident < $($types:ident),* > assoc $($atypes:ident = $aty:ty),*) => {
impl_downcast! { @impl_full_sync $trait_ [$($types),*, $($atypes = $aty),*] for [] where [] }
};
}
#[cfg(test)]
mod test {
macro_rules! test_mod {
(
$test_mod_name:ident,
trait $base_trait:path { $($base_impl:tt)* },
non_sync: { $($non_sync_def:tt)+ },
sync: { $($sync_def:tt)+ }
) => {
test_mod! {
$test_mod_name,
trait $base_trait { $($base_impl:tt)* },
type dyn $base_trait,
non_sync: { $($non_sync_def)* },
sync: { $($sync_def)* }
}
};
(
$test_mod_name:ident,
trait $base_trait:path { $($base_impl:tt)* },
type $base_type:ty,
non_sync: { $($non_sync_def:tt)+ },
sync: { $($sync_def:tt)+ }
) => {
mod $test_mod_name {
test_mod!(
@test
$test_mod_name,
test_name: test_non_sync,
trait $base_trait { $($base_impl)* },
type $base_type,
{ $($non_sync_def)+ },
[]);
test_mod!(
@test
$test_mod_name,
test_name: test_sync,
trait $base_trait { $($base_impl)* },
type $base_type,
{ $($sync_def)+ },
[{
// Fail to convert Arc<Base> into Arc<Bar>.
let arc: $crate::__alloc::sync::Arc<$base_type> = $crate::__alloc::sync::Arc::new(Foo(42));
let res = arc.downcast_arc::<Bar>();
assert!(res.is_err());
let arc = res.unwrap_err();
// Convert Arc<Base> into Arc<Foo>.
assert_eq!(
42, arc.downcast_arc::<Foo>().map_err(|_| "Shouldn't happen.").unwrap().0);
}]);
}
};
(
@test
$test_mod_name:ident,
test_name: $test_name:ident,
trait $base_trait:path { $($base_impl:tt)* },
type $base_type:ty,
{ $($def:tt)+ },
[ $($more_tests:block)* ]
) => {
#[test]
fn $test_name() {
#[allow(unused_imports)]
use super::super::{Downcast, DowncastSync};
// Should work even if standard objects (especially those in the prelude) are
// aliased to something else.
#[allow(dead_code)] struct Any;
#[allow(dead_code)] struct Arc;
#[allow(dead_code)] struct Box;
#[allow(dead_code)] struct Option;
#[allow(dead_code)] struct Result;
#[allow(dead_code)] struct Rc;
#[allow(dead_code)] struct Send;
#[allow(dead_code)] struct Sync;
// A trait that can be downcast.
$($def)*
// Concrete type implementing Base.
#[derive(Debug)]
struct Foo(u32);
impl $base_trait for Foo { $($base_impl)* }
#[derive(Debug)]
struct Bar(f64);
impl $base_trait for Bar { $($base_impl)* }
// Functions that can work on references to Base trait objects.
fn get_val(base: &$crate::__alloc::boxed::Box<$base_type>) -> u32 {
match base.downcast_ref::<Foo>() {
Some(val) => val.0,
None => 0
}
}
fn set_val(base: &mut $crate::__alloc::boxed::Box<$base_type>, val: u32) {
if let Some(foo) = base.downcast_mut::<Foo>() {
foo.0 = val;
}
}
let mut base: $crate::__alloc::boxed::Box<$base_type> = $crate::__alloc::boxed::Box::new(Foo(42));
assert_eq!(get_val(&base), 42);
// Try sequential downcasts.
if let Some(foo) = base.downcast_ref::<Foo>() {
assert_eq!(foo.0, 42);
} else if let Some(bar) = base.downcast_ref::<Bar>() {
assert_eq!(bar.0, 42.0);
}
set_val(&mut base, 6*9);
assert_eq!(get_val(&base), 6*9);
assert!(base.is::<Foo>());
// Fail to convert Box<Base> into Box<Bar>.
let res = base.downcast::<Bar>();
assert!(res.is_err());
let base = res.unwrap_err();
// Convert Box<Base> into Box<Foo>.
assert_eq!(
6*9, base.downcast::<Foo>().map_err(|_| "Shouldn't happen.").unwrap().0);
// Fail to convert Rc<Base> into Rc<Bar>.
let rc: $crate::__alloc::rc::Rc<$base_type> = $crate::__alloc::rc::Rc::new(Foo(42));
let res = rc.downcast_rc::<Bar>();
assert!(res.is_err());
let rc = res.unwrap_err();
// Convert Rc<Base> into Rc<Foo>.
assert_eq!(
42, rc.downcast_rc::<Foo>().map_err(|_| "Shouldn't happen.").unwrap().0);
$($more_tests)*
}
};
(
$test_mod_name:ident,
trait $base_trait:path { $($base_impl:tt)* },
non_sync: { $($non_sync_def:tt)+ },
sync: { $($sync_def:tt)+ }
) => {
test_mod! {
$test_mod_name,
trait $base_trait { $($base_impl:tt)* },
type $base_trait,
non_sync: { $($non_sync_def)* },
sync: { $($sync_def)* }
}
};
}
test_mod!(non_generic, trait Base {},
non_sync: {
trait Base: Downcast {}
impl_downcast!(Base);
},
sync: {
trait Base: DowncastSync {}
impl_downcast!(sync Base);
});
test_mod!(generic, trait Base<u32> {},
non_sync: {
trait Base<T>: Downcast {}
impl_downcast!(Base<T>);
},
sync: {
trait Base<T>: DowncastSync {}
impl_downcast!(sync Base<T>);
});
test_mod!(constrained_generic, trait Base<u32> {},
non_sync: {
trait Base<T: Copy>: Downcast {}
impl_downcast!(Base<T> where T: Copy);
},
sync: {
trait Base<T: Copy>: DowncastSync {}
impl_downcast!(sync Base<T> where T: Copy);
});
test_mod!(associated,
trait Base { type H = f32; },
type dyn Base<H=f32>,
non_sync: {
trait Base: Downcast { type H; }
impl_downcast!(Base assoc H);
},
sync: {
trait Base: DowncastSync { type H; }
impl_downcast!(sync Base assoc H);
});
test_mod!(constrained_associated,
trait Base { type H = f32; },
type dyn Base<H=f32>,
non_sync: {
trait Base: Downcast { type H: Copy; }
impl_downcast!(Base assoc H where H: Copy);
},
sync: {
trait Base: DowncastSync { type H: Copy; }
impl_downcast!(sync Base assoc H where H: Copy);
});
test_mod!(param_and_associated,
trait Base<u32> { type H = f32; },
type dyn Base<u32, H=f32>,
non_sync: {
trait Base<T>: Downcast { type H; }
impl_downcast!(Base<T> assoc H);
},
sync: {
trait Base<T>: DowncastSync { type H; }
impl_downcast!(sync Base<T> assoc H);
});
test_mod!(constrained_param_and_associated,
trait Base<u32> { type H = f32; },
type dyn Base<u32, H=f32>,
non_sync: {
trait Base<T: Clone>: Downcast { type H: Copy; }
impl_downcast!(Base<T> assoc H where T: Clone, H: Copy);
},
sync: {
trait Base<T: Clone>: DowncastSync { type H: Copy; }
impl_downcast!(sync Base<T> assoc H where T: Clone, H: Copy);
});
test_mod!(concrete_parametrized, trait Base<u32> {},
non_sync: {
trait Base<T>: Downcast {}
impl_downcast!(concrete Base<u32>);
},
sync: {
trait Base<T>: DowncastSync {}
impl_downcast!(sync concrete Base<u32>);
});
test_mod!(concrete_associated,
trait Base { type H = u32; },
type dyn Base<H=u32>,
non_sync: {
trait Base: Downcast { type H; }
impl_downcast!(concrete Base assoc H=u32);
},
sync: {
trait Base: DowncastSync { type H; }
impl_downcast!(sync concrete Base assoc H=u32);
});
test_mod!(concrete_parametrized_associated,
trait Base<u32> { type H = f32; },
type dyn Base<u32, H=f32>,
non_sync: {
trait Base<T>: Downcast { type H; }
impl_downcast!(concrete Base<u32> assoc H=f32);
},
sync: {
trait Base<T>: DowncastSync { type H; }
impl_downcast!(sync concrete Base<u32> assoc H=f32);
});
}