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.).
84 lines
2.2 KiB
Rust
84 lines
2.2 KiB
Rust
//@ check-pass
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//! A struct must have a well-defined layout to participate in a transmutation.
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#![crate_type = "lib"]
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#![feature(transmutability)]
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#![allow(dead_code, incomplete_features, non_camel_case_types)]
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mod assert {
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use std::mem::{Assume, BikeshedIntrinsicFrom};
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pub fn is_maybe_transmutable<Src, Dst>()
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where
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Dst: BikeshedIntrinsicFrom<Src, {
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Assume {
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alignment: true,
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lifetimes: true,
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safety: true,
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validity: true,
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}
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}>
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{}
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}
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fn should_accept_repr_rust()
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{
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fn unit() {
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struct repr_rust;
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assert::is_maybe_transmutable::<repr_rust, ()>();
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assert::is_maybe_transmutable::<u128, repr_rust>();
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}
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fn tuple() {
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struct repr_rust();
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assert::is_maybe_transmutable::<repr_rust, ()>();
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assert::is_maybe_transmutable::<u128, repr_rust>();
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}
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fn braces() {
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struct repr_rust{}
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assert::is_maybe_transmutable::<repr_rust, ()>();
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assert::is_maybe_transmutable::<u128, repr_rust>();
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}
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fn aligned() {
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#[repr(align(1))] struct repr_rust{}
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assert::is_maybe_transmutable::<repr_rust, ()>();
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assert::is_maybe_transmutable::<u128, repr_rust>();
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}
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fn packed() {
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#[repr(packed)] struct repr_rust{}
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assert::is_maybe_transmutable::<repr_rust, ()>();
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assert::is_maybe_transmutable::<u128, repr_rust>();
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}
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fn nested() {
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struct repr_rust;
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#[repr(C)] struct repr_c(repr_rust);
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assert::is_maybe_transmutable::<repr_c, ()>();
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assert::is_maybe_transmutable::<u128, repr_c>();
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}
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}
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fn should_accept_repr_c()
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{
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fn unit() {
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#[repr(C)] struct repr_c;
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assert::is_maybe_transmutable::<repr_c, ()>();
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assert::is_maybe_transmutable::<i128, repr_c>();
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}
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fn tuple() {
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#[repr(C)] struct repr_c();
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assert::is_maybe_transmutable::<repr_c, ()>();
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assert::is_maybe_transmutable::<i128, repr_c>();
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}
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fn braces() {
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#[repr(C)] struct repr_c{}
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assert::is_maybe_transmutable::<repr_c, ()>();
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assert::is_maybe_transmutable::<i128, repr_c>();
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}
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}
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