mirror of https://github.com/rust-lang/rust
43 lines
1.3 KiB
Rust
43 lines
1.3 KiB
Rust
// Check that an 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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#![feature(rustc_private)]
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extern crate rustc_arena;
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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>(_arena: &'a TypedArena<C<'a>>) {}
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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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} //~^ ERROR `arena` does not live long enough
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