50 lines
1.7 KiB
Rust
50 lines
1.7 KiB
Rust
// Copyright 2012-2014 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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// Various tests related to testing how region inference works
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// with respect to the object receivers.
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trait Foo {
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fn borrowed<'a>(&'a self) -> &'a ();
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}
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// Here the receiver and return value all have the same lifetime,
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// so no error results.
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fn borrowed_receiver_same_lifetime<'a>(x: &'a Foo) -> &'a () {
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x.borrowed()
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}
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// Borrowed receiver but two distinct lifetimes, we get an error.
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fn borrowed_receiver_different_lifetimes<'a,'b>(x: &'a Foo) -> &'b () {
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x.borrowed() //~ ERROR cannot infer
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}
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// Borrowed receiver with two distinct lifetimes, but we know that
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// 'b:'a, hence &'a () is permitted.
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fn borrowed_receiver_related_lifetimes<'a,'b>(x: &'a (Foo+'b)) -> &'a () {
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x.borrowed()
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}
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// Here we have two distinct lifetimes, but we try to return a pointer
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// with the longer lifetime when (from the signature) we only know
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// that it lives as long as the shorter lifetime. Therefore, error.
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fn borrowed_receiver_related_lifetimes2<'a,'b>(x: &'a (Foo+'b)) -> &'b () {
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x.borrowed() //~ ERROR cannot infer
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}
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// Here, the object is bounded by an anonymous lifetime and returned
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// as `&'static`, so you get an error.
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fn owned_receiver(x: Box<Foo>) -> &'static () {
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x.borrowed() //~ ERROR cannot infer
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}
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fn main() {}
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