3aa14e3b2e
In its first step of computing transmutability, `rustc_transmutability` constructs a byte-level representation of type layout (`Tree`). Previously, this representation was computed for ADTs by inspecting the ADT definition and performing our own layout computations. This process was error-prone, verbose, and limited our ability to analyze many types (particularly default-repr types). In this PR, we instead construct `Tree`s from `rustc_target::abi::Layout`s. This helps ensure that layout optimizations are reflected our analyses, and increases the kinds of types we can now analyze, including: - default repr ADTs - transparent unions - `UnsafeCell`-containing types Overall, this PR expands the expressvity of `rustc_transmutability` to be much closer to the transmutability analysis performed by miri. Future PRs will work to close the remaining gaps (e.g., support for `Box`, raw pointers, `NonZero*`, coroutines, etc.).
56 lines
1.1 KiB
Rust
56 lines
1.1 KiB
Rust
//@ check-pass
|
|
|
|
#![crate_type = "lib"]
|
|
#![feature(transmutability, transparent_unions)]
|
|
#![allow(dead_code, incomplete_features, non_camel_case_types)]
|
|
|
|
mod assert {
|
|
use std::mem::{Assume, BikeshedIntrinsicFrom};
|
|
|
|
pub fn is_maybe_transmutable<Src, Dst>()
|
|
where
|
|
Dst: BikeshedIntrinsicFrom<Src, {
|
|
Assume {
|
|
alignment: true,
|
|
lifetimes: true,
|
|
safety: true,
|
|
validity: true,
|
|
}
|
|
}>
|
|
{}
|
|
}
|
|
|
|
fn should_accept_repr_rust()
|
|
{
|
|
union repr_rust {
|
|
a: u8
|
|
}
|
|
|
|
assert::is_maybe_transmutable::<repr_rust, ()>();
|
|
assert::is_maybe_transmutable::<u128, repr_rust>();
|
|
}
|
|
|
|
fn should_accept_repr_c()
|
|
{
|
|
#[repr(C)]
|
|
union repr_c {
|
|
a: u8
|
|
}
|
|
|
|
struct repr_rust;
|
|
assert::is_maybe_transmutable::<repr_c, ()>();
|
|
assert::is_maybe_transmutable::<u128, repr_c>();
|
|
}
|
|
|
|
|
|
fn should_accept_transparent()
|
|
{
|
|
#[repr(transparent)]
|
|
union repr_transparent {
|
|
a: u8
|
|
}
|
|
|
|
assert::is_maybe_transmutable::<repr_transparent, ()>();
|
|
assert::is_maybe_transmutable::<u128, repr_transparent>();
|
|
}
|