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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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2
compiler/rustc_transmute/src/maybe_transmutable/mod.rs
View file

@ -105,7 +105,7 @@ where
#[inline(always)]
#[instrument(level = "debug", skip(self), fields(src = ?self.src, dst = ?self.dst))]
pub(crate) fn answer(self) -> Answer<<C as QueryContext>::Ref> {
let assume_visibility = self.assume.visibility;
let assume_visibility = self.assume.safety;
let query_or_answer = self.map_layouts(|src, dst, scope, context| {
// Remove all `Def` nodes from `src`, without checking their visibility.
let src = src.prune(&|def| true);

4
compiler/rustc_transmute/src/maybe_transmutable/tests.rs
View file

@ -13,7 +13,7 @@ mod bool {
layout::Tree::<Def, !>::bool(),
layout::Tree::<Def, !>::bool(),
(),
crate::Assume { alignment: false, lifetimes: false, validity: true, visibility: false },
crate::Assume { alignment: false, lifetimes: false, validity: true, safety: false },
UltraMinimal,
)
.answer();
@ -26,7 +26,7 @@ mod bool {
layout::Dfa::<!>::bool(),
layout::Dfa::<!>::bool(),
(),
crate::Assume { alignment: false, lifetimes: false, validity: true, visibility: false },
crate::Assume { alignment: false, lifetimes: false, validity: true, safety: false },
UltraMinimal,
)
.answer();