54 lines
1.9 KiB
Rust
54 lines
1.9 KiB
Rust
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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// Test that duplicate auto trait bounds in trait objects don't create new types.
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#[allow(unused_assignments)]
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use std::marker::Send as SendAlias;
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// A dummy trait for the non-auto trait.
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trait Trait {}
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// A dummy struct to implement Trait, Send, and .
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struct Struct;
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impl Trait for Struct {}
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// These three functions should be equivalent.
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fn takes_dyn_trait_send(_: Box<dyn Trait + Send>) {}
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fn takes_dyn_trait_send_send(_: Box<dyn Trait + Send + Send>) {}
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fn takes_dyn_trait_send_sendalias(_: Box<dyn Trait + Send + SendAlias>) {}
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impl dyn Trait + Send + Send {
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fn do_nothing(&self) {}
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}
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fn main() {
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// 1. Moving into a variable with more Sends and back.
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let mut dyn_trait_send = Box::new(Struct) as Box<dyn Trait + Send>;
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let dyn_trait_send_send: Box<dyn Trait + Send + Send> = dyn_trait_send;
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dyn_trait_send = dyn_trait_send_send;
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// 2. Calling methods with different number of Sends.
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let dyn_trait_send = Box::new(Struct) as Box<dyn Trait + Send>;
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takes_dyn_trait_send_send(dyn_trait_send);
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let dyn_trait_send_send = Box::new(Struct) as Box<dyn Trait + Send + Send>;
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takes_dyn_trait_send(dyn_trait_send_send);
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// 3. Aliases to the trait are transparent.
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let dyn_trait_send = Box::new(Struct) as Box<dyn Trait + Send>;
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takes_dyn_trait_send_sendalias(dyn_trait_send);
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// 4. Calling an impl that duplicates an auto trait.
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let dyn_trait_send = Box::new(Struct) as Box<dyn Trait + Send>;
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dyn_trait_send.do_nothing();
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}
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