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Auto merge of #100726 - jswrenn:transmute, r=oli-obk

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safe transmute: use `Assume` struct to provide analysis options

This task was left as a TODO in #92268; resolving it brings [`BikeshedIntrinsicFrom`](https://doc.rust-lang.org/nightly/core/mem/trait.BikeshedIntrinsicFrom.html) more in line with the API defined in [MCP411](https://github.com/rust-lang/compiler-team/issues/411).

**Before:**
```rust
pub unsafe trait BikeshedIntrinsicFrom<
    Src,
    Context,
    const ASSUME_ALIGNMENT: bool,
    const ASSUME_LIFETIMES: bool,
    const ASSUME_VALIDITY: bool,
    const ASSUME_VISIBILITY: bool,
> where
    Src: ?Sized,
{}
```
**After:**
```rust
pub unsafe trait BikeshedIntrinsicFrom<Src, Context, const ASSUME: Assume = { Assume::NOTHING }>
where
    Src: ?Sized,
{}
```

`Assume::visibility` has also been renamed to `Assume::safety`, as library safety invariants are what's actually being assumed; visibility is just the mechanism by which it is currently checked (and that may change).

r? `@oli-obk`

---

Related:
- https://github.com/rust-lang/compiler-team/issues/411
- https://github.com/rust-lang/rust/issues/99571
This commit is contained in:
bors 2022-09-04 07:55:44 +00:00
commit 8521a8c92d
79 changed files with 1320 additions and 735 deletions
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20
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View file

@ -279,29 +279,17 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let predicate = obligation.predicate;
let type_at = |i| predicate.map_bound(|p| p.trait_ref.substs.type_at(i));
let bool_at = |i| {
predicate
.skip_binder()
.trait_ref
.substs
.const_at(i)
.try_eval_bool(self.tcx(), obligation.param_env)
.unwrap_or(true)
};
let const_at = |i| predicate.skip_binder().trait_ref.substs.const_at(i);
let src_and_dst = predicate.map_bound(|p| rustc_transmute::Types {
src: p.trait_ref.substs.type_at(1),
dst: p.trait_ref.substs.type_at(0),
src: p.trait_ref.substs.type_at(1),
});
let scope = type_at(2).skip_binder();
let assume = rustc_transmute::Assume {
alignment: bool_at(3),
lifetimes: bool_at(4),
validity: bool_at(5),
visibility: bool_at(6),
};
let assume =
rustc_transmute::Assume::from_const(self.infcx.tcx, obligation.param_env, const_at(3));
let cause = obligation.cause.clone();