c1cda0793e
Some compile-fail tests illustrated cases to be rejected by dropck, including ones that check cyclic data cases designed to exposed bugs if they are actually tricked into running by an unsound analysis. E.g. these exposed bugs in earlier broken ways of handling `Vec<T>`. (Note that all the uses of `unsafe_destructor` are just placating the simple analysis used for that feature, which will eventually go away once we have put the dropck through its paces.)
55 lines
1.8 KiB
Rust
55 lines
1.8 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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// Check that a arena (TypedArena) cannot carry elements whose drop
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// methods might access borrowed data of lifetime that does not
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// strictly outlive the arena itself.
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//
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// Compare against run-pass/dropck_tarena_sound_drop.rs, which shows a
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// similar setup, but loosens `f` so that the struct `C<'a>` can be
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// fed a lifetime longer than that of the arena.
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//
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// (Also compare against dropck_tarena_cycle_checked.rs, from which
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// this was reduced to better understand its error message.)
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#![allow(unstable)]
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#![feature(unsafe_destructor)]
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extern crate arena;
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use arena::TypedArena;
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trait HasId { fn count(&self) -> usize; }
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struct CheckId<T:HasId> { v: T }
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// In the code below, the impl of HasId for `&'a usize` does not
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// actually access the borrowed data, but the point is that the
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// interface to CheckId does not (and cannot) know that, and therefore
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// when encountering the a value V of type CheckId<S>, we must
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// conservatively force the type S to strictly outlive V.
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#[unsafe_destructor]
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impl<T:HasId> Drop for CheckId<T> {
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fn drop(&mut self) {
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assert!(self.v.count() > 0);
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}
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}
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struct C<'a> { v: CheckId<&'a usize>, }
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impl<'a> HasId for &'a usize { fn count(&self) -> usize { 1 } }
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fn f<'a>(_arena: &'a TypedArena<C<'a>>) {}
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fn main() {
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let arena: TypedArena<C> = TypedArena::new();
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f(&arena); //~ ERROR `arena` does not live long enough
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}
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