7a4743fab0
(It is not *exactly* the text from the RFC, but the only thing it adds is a call to a no-op function that is just an attempt to make it clear where the potential for impl specialization comes from.)
49 lines
1.6 KiB
Rust
49 lines
1.6 KiB
Rust
// Copyright 2015 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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// Example taken from RFC 1238 text
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// https://github.com/rust-lang/rfcs/blob/master/text/1238-nonparametric-dropck.md
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// #examples-of-code-that-will-start-to-be-rejected
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// Compare against test/run-pass/issue28498-must-work-ex2.rs
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use std::cell::Cell;
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struct Concrete<'a>(u32, Cell<Option<&'a Concrete<'a>>>);
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struct Foo<T> { data: Vec<T> }
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fn potentially_specialized_wrt_t<T>(t: &T) {
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// Hypothetical code that does one thing for generic T and then is
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// specialized for T == Concrete (and the specialized form can
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// then access a reference held in concrete tuple).
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//
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// (We don't have specialization yet, but we want to allow for it
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// in the future.)
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}
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impl<T> Drop for Foo<T> {
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fn drop(&mut self) {
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potentially_specialized_wrt_t(&self.data[0])
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}
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}
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fn main() {
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let mut foo = Foo { data: Vec::new() };
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foo.data.push(Concrete(0, Cell::new(None)));
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foo.data.push(Concrete(0, Cell::new(None)));
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foo.data[0].1.set(Some(&foo.data[1]));
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//~^ ERROR `foo.data` does not live long enough
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foo.data[1].1.set(Some(&foo.data[0]));
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//~^ ERROR `foo.data` does not live long enough
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}
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