8f1cec8d84
This patch enables support for references in Safe Transmute, by generating nested obligations during trait selection. Specifically, when we call `confirm_transmutability_candidate(...)`, we now recursively traverse the `rustc_transmute::Answer` tree and create obligations for all the `Answer` variants, some of which include multiple nested `Answer`s. Also, to handle recursive types, enable support for coinduction for the Safe Transmute trait (`BikeshedIntrinsicFrom`) by adding the `#[rustc_coinduction]` annotation. Also fix some small logic issues when reducing the `or` and `and` combinations in `rustc_transmute`, so that we don't end up with additional redundant `Answer`s in the tree. Co-authored-by: Jack Wrenn <jack@wrenn.fyi>
25 lines
536 B
Rust
25 lines
536 B
Rust
// check-pass
|
|
#![feature(transmutability)]
|
|
|
|
mod assert {
|
|
use std::mem::{Assume, BikeshedIntrinsicFrom};
|
|
pub struct Context;
|
|
|
|
pub fn is_maybe_transmutable<Src, Dst>()
|
|
where
|
|
Dst: BikeshedIntrinsicFrom<Src, Context, {
|
|
Assume {
|
|
alignment: true,
|
|
lifetimes: false,
|
|
safety: true,
|
|
validity: false,
|
|
}
|
|
}>
|
|
{}
|
|
}
|
|
|
|
fn main() {
|
|
#[repr(C)] struct Unit;
|
|
assert::is_maybe_transmutable::<&'static Unit, &'static Unit>();
|
|
}
|