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