File: ptr-to-trait-obj-drop-principal.rs

package info (click to toggle)
rustc 1.87.0%2Bdfsg1-1
  • links: PTS, VCS
  • area: main
  • in suites: forky, sid
  • size: 925,564 kB
  • sloc: xml: 158,127; python: 36,039; javascript: 19,761; sh: 19,737; cpp: 18,981; ansic: 13,133; asm: 4,376; makefile: 710; perl: 29; lisp: 28; ruby: 19; sql: 11
file content (21 lines) | stat: -rw-r--r-- 595 bytes parent folder | download | duplicates (15)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
//! Test that non-coercion casts aren't allowed to drop the principal,
//! because they cannot modify the pointer metadata.
//!
//! We test this in a const context to guard against UB if this is allowed
//! in the future.

trait Trait {}
impl Trait for () {}

struct Wrapper<T: ?Sized>(T);

const OBJECT: *const (dyn Trait + Send) = &();

// coercions are allowed
const _: *const dyn Send = OBJECT as _;

// casts are **not** allowed
const _: *const Wrapper<dyn Send> = OBJECT as _;
//~^ ERROR casting `*const (dyn Trait + Send + 'static)` as `*const Wrapper<dyn Send>` is invalid

fn main() {}