mirror of https://github.com/rust-lang/rust
49 lines
1.4 KiB
Rust
49 lines
1.4 KiB
Rust
//@ run-pass
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#![allow(unknown_lints)]
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// Check that an arena (TypedArena) can carry elements whose drop
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// methods might access borrowed data, as long as the borrowed data
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// has lifetime that strictly outlives the arena itself.
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//
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// Compare against ui-fulldeps/dropck-tarena-unsound-drop.rs, which
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// shows a similar setup, but restricts `f` so that the struct `C<'a>`
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// is force-fed a lifetime equal to that of the borrowed arena.
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#![allow(unstable)]
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#![feature(rustc_private)]
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extern crate rustc_arena;
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// Necessary to pull in object code as the rest of the rustc crates are shipped only as rmeta
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// files.
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#[allow(unused_extern_crates)]
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extern crate rustc_driver;
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use rustc_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 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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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, 'b>(_arena: &'a TypedArena<C<'b>>) {}
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fn main() {
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let arena: TypedArena<C> = TypedArena::default();
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f(&arena);
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}
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