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ty: handle UnsafeBinder in pointer_kind, metadata, and projections #565

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ty: handle UnsafeBinder in pointer_kind, metadata, and projections #565

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7 changes: 6 additions & 1 deletion compiler/rustc_hir_typeck/src/cast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -118,7 +118,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
Some(&f) => self.pointer_kind(f, span)?,
},

ty::UnsafeBinder(_) => todo!("FIXME(unsafe_binder)"),
// Pointer kind follows the inner type once binder regions are erased,
// matching `discriminant_ty` / other ty queries on unsafe binders.
ty::UnsafeBinder(bound_ty) => {
let inner = self.tcx.instantiate_bound_regions_with_erased((*bound_ty).into());
self.pointer_kind(inner, span)?
}

// Pointers to foreign types are thin, despite being unsized
ty::Foreign(..) => Some(PointerKind::Thin),
Expand Down
7 changes: 6 additions & 1 deletion compiler/rustc_middle/src/ty/sty.rs
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Expand Up @@ -1790,7 +1790,12 @@ impl<'tcx> Ty<'tcx> {
// metadata of `tail`.
ty::Param(_) | ty::Alias(..) => Err(tail),

ty::UnsafeBinder(_) => todo!("FIXME(unsafe_binder)"),
// Metadata of an unsafe binder is the metadata of its inner type
// (regions erased), same as other queries on `UnsafeBinder`.
ty::UnsafeBinder(bound_ty) => {
tcx.instantiate_bound_regions_with_erased((*bound_ty).into())
.ptr_metadata_ty_or_tail(tcx, normalize)
}

ty::Infer(ty::TyVar(_))
| ty::Pat(..)
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_middle/src/ty/util.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1268,8 +1268,8 @@ impl<'tcx> Ty<'tcx> {
| ty::FnDef(..)
| ty::Error(_)
| ty::FnPtr(..) => true,
// FIXME(unsafe_binders):
ty::UnsafeBinder(_) => todo!(),
// Without `TyCtxt` we cannot erase binder regions; be conservative.
ty::UnsafeBinder(_) => false,
ty::Tuple(fields) => fields.iter().all(Self::is_trivially_not_async_drop),
ty::Pat(elem_ty, _) | ty::Slice(elem_ty) | ty::Array(elem_ty, _) => {
elem_ty.is_trivially_not_async_drop()
Expand Down
77 changes: 75 additions & 2 deletions compiler/rustc_trait_selection/src/traits/project.rs
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Expand Up @@ -1084,7 +1084,40 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
// Integers and floats always have `u8` as their discriminant.
| ty::Infer(ty::InferTy::IntVar(_) | ty::InferTy::FloatVar(..)) => true,

ty::UnsafeBinder(_) => todo!("FIXME(unsafe_binder)"),
// DiscriminantKind on unsafe binders follows the inner type (see `discriminant_ty`).
ty::UnsafeBinder(bound_ty) => {
let inner = selcx
.tcx()
.instantiate_bound_regions_with_erased((*bound_ty).into());
match inner.kind() {
ty::Bool
| ty::Char
| ty::Int(_)
| ty::Uint(_)
| ty::Float(_)
| ty::Adt(..)
| ty::Foreign(_)
| ty::Str
| ty::Array(..)
| ty::Pat(..)
| ty::Slice(_)
| ty::RawPtr(..)
| ty::Ref(..)
| ty::FnDef(..)
| ty::FnPtr(..)
| ty::Dynamic(..)
| ty::Closure(..)
| ty::CoroutineClosure(..)
| ty::Coroutine(..)
| ty::CoroutineWitness(..)
| ty::Never
| ty::Tuple(..)
| ty::Infer(
ty::InferTy::IntVar(_) | ty::InferTy::FloatVar(..),
) => true,
_ => false,
}
}

// type parameters, opaques, and unnormalized projections don't have
// a known discriminant and may need to be normalized further or rely
Expand Down Expand Up @@ -1169,7 +1202,47 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
true
}

ty::UnsafeBinder(_) => todo!("FIXME(unsafe_binder)"),
// Pointee/metadata of an unsafe binder is that of the inner type.
ty::UnsafeBinder(bound_ty) => {
let inner = selcx
.tcx()
.instantiate_bound_regions_with_erased((*bound_ty).into());
match *inner.kind() {
ty::Bool
| ty::Char
| ty::Int(_)
| ty::Uint(_)
| ty::Float(_)
| ty::Str
| ty::Array(..)
| ty::Pat(..)
| ty::Slice(_)
| ty::RawPtr(..)
| ty::Ref(..)
| ty::FnDef(..)
| ty::FnPtr(..)
| ty::Dynamic(..)
| ty::Closure(..)
| ty::CoroutineClosure(..)
| ty::Coroutine(..)
| ty::CoroutineWitness(..)
| ty::Never
| ty::Foreign(_)
| ty::Adt(..)
| ty::Tuple(..)
| ty::Infer(
ty::InferTy::IntVar(_) | ty::InferTy::FloatVar(..),
)
| ty::Error(..) => true,
ty::Param(_) | ty::Alias(..) if self_ty != tail => true,
_ => {
if tail.has_infer_types() {
candidate_set.mark_ambiguous();
}
false
}
}
}

// FIXME(compiler-errors): are Bound and Placeholder types ever known sized?
ty::Param(_)
Expand Down