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// aux-build:dropck_eyepatch_extern_crate.rs
// The point of this test is to illustrate that the `#[may_dangle]`
// attribute specifically allows, in the context of a type
// implementing `Drop`, a generic parameter to be instantiated with a
// lifetime that does not strictly outlive the owning type itself,
// and that this attribute's effects are preserved when importing
// the type from another crate.
//
// See also dropck-eyepatch.rs for more information about the general
// structure of the test.
extern crate dropck_eyepatch_extern_crate as other;
use other::{Dt,Dr,Pt,Pr,St,Sr};
fn main() {
use std::cell::Cell;
// We use separate blocks with separate variable to prevent the error
// messages from being deduplicated.
{
let c_long;
let (mut dt, mut dr): (Dt<_>, Dr<_>);
c_long = Cell::new(1);
// No error: sufficiently long-lived state can be referenced in dtors
dt = Dt("dt", &c_long);
dr = Dr("dr", &c_long);
}
{
let (c, mut dt, mut dr): (Cell<_>, Dt<_>, Dr<_>);
c = Cell::new(1);
// No Error: destructor order precisely modelled
dt = Dt("dt", &c);
dr = Dr("dr", &c);
}
{
let (mut dt, mut dr, c_shortest): (Dt<_>, Dr<_>, Cell<_>);
c_shortest = Cell::new(1);
// Error: `c_shortest` dies too soon for the references in dtors to be valid.
dt = Dt("dt", &c_shortest);
//~^ ERROR `c_shortest` does not live long enough
dr = Dr("dr", &c_shortest);
}
{
let c_long;
let (mut pt, mut pr, c_shortest): (Pt<_, _>, Pr<_>, Cell<_>);
c_long = Cell::new(1);
c_shortest = Cell::new(1);
// No error: Drop impl asserts .1 (A and &'a _) are not accessed
pt = Pt("pt", &c_shortest, &c_long);
pr = Pr("pr", &c_shortest, &c_long);
}
{
let c_long;
let (mut pt, mut pr, c_shortest): (Pt<_, _>, Pr<_>, Cell<_>);
c_long = Cell::new(1);
c_shortest = Cell::new(1);
// Error: Drop impl's assertion does not apply to `B` nor `&'b _`
pt = Pt("pt", &c_long, &c_shortest);
//~^ ERROR `c_shortest` does not live long enough
pr = Pr("pr", &c_long, &c_shortest);
}
{
let (st, sr, c_shortest): (St<_>, Sr<_>, Cell<_>);
c_shortest = Cell::new(1);
// No error: St and Sr have no destructor.
st = St("st", &c_shortest);
sr = Sr("sr", &c_shortest);
}
}
fn use_imm<T>(_: &T) { }
|
