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Auto merge of rust-lang#133393 - compiler-errors:dyn-tweaks, r=lcnr,s…
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…pastorino

Some minor dyn-related tweaks

Each commit should be self-explanatory, but I'm happy to explain what's going on if not. These are tweaks I pulled out of rust-lang#133388, but they can be reviewed sooner than that.

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bors committed Nov 27, 2024
2 parents 39cb338 + bcfc8ab commit c322cd5
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Showing 4 changed files with 11 additions and 74 deletions.
3 changes: 1 addition & 2 deletions compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -136,7 +136,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {

for (base_trait_ref, original_span) in regular_traits_refs_spans {
let base_pred: ty::Predicate<'tcx> = base_trait_ref.upcast(tcx);
for ClauseWithSupertraitSpan { pred, original_span, supertrait_span } in
for ClauseWithSupertraitSpan { pred, supertrait_span } in
traits::elaborate(tcx, [ClauseWithSupertraitSpan::new(base_pred, original_span)])
.filter_only_self()
{
Expand Down Expand Up @@ -204,7 +204,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
for def_ids in associated_types.values_mut() {
for (projection_bound, span) in &projection_bounds {
let def_id = projection_bound.projection_def_id();
// FIXME(#120456) - is `swap_remove` correct?
def_ids.swap_remove(&def_id);
if tcx.generics_require_sized_self(def_id) {
tcx.emit_node_span_lint(
Expand Down
35 changes: 1 addition & 34 deletions compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -727,7 +727,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
let tcx = self.tcx();
// FIXME: Marked `mut` so that we can replace the spans further below with a more
// appropriate one, but this should be handled earlier in the span assignment.
let mut associated_types: FxIndexMap<Span, Vec<_>> = associated_types
let associated_types: FxIndexMap<Span, Vec<_>> = associated_types
.into_iter()
.map(|(span, def_ids)| {
(span, def_ids.into_iter().map(|did| tcx.associated_item(did)).collect())
Expand Down Expand Up @@ -769,39 +769,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
hir::Node::Expr(_) | hir::Node::Pat(_) => true,
_ => false,
};
match bound.trait_ref.path.segments {
// FIXME: `trait_ref.path.span` can point to a full path with multiple
// segments, even though `trait_ref.path.segments` is of length `1`. Work
// around that bug here, even though it should be fixed elsewhere.
// This would otherwise cause an invalid suggestion. For an example, look at
// `tests/ui/issues/issue-28344.rs` where instead of the following:
//
// error[E0191]: the value of the associated type `Output`
// (from trait `std::ops::BitXor`) must be specified
// --> $DIR/issue-28344.rs:4:17
// |
// LL | let x: u8 = BitXor::bitor(0 as u8, 0 as u8);
// | ^^^^^^ help: specify the associated type:
// | `BitXor<Output = Type>`
//
// we would output:
//
// error[E0191]: the value of the associated type `Output`
// (from trait `std::ops::BitXor`) must be specified
// --> $DIR/issue-28344.rs:4:17
// |
// LL | let x: u8 = BitXor::bitor(0 as u8, 0 as u8);
// | ^^^^^^^^^^^^^ help: specify the associated type:
// | `BitXor::bitor<Output = Type>`
[segment] if segment.args.is_none() => {
trait_bound_spans = vec![segment.ident.span];
associated_types = associated_types
.into_values()
.map(|items| (segment.ident.span, items))
.collect();
}
_ => {}
}
}

// We get all the associated items that _are_ set,
Expand Down
36 changes: 7 additions & 29 deletions compiler/rustc_trait_selection/src/traits/wf.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -963,30 +963,7 @@ impl<'a, 'tcx> TypeVisitor<TyCtxt<'tcx>> for WfPredicates<'a, 'tcx> {
/// bounds that must hold on the elided self type. These are derived
/// from the declarations of `SomeTrait`, `Send`, and friends -- if
/// they declare `trait SomeTrait : 'static`, for example, then
/// `'static` would appear in the list. The hard work is done by
/// `infer::required_region_bounds`, see that for more information.
pub fn object_region_bounds<'tcx>(
tcx: TyCtxt<'tcx>,
existential_predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
) -> Vec<ty::Region<'tcx>> {
let predicates = existential_predicates.iter().filter_map(|predicate| {
if let ty::ExistentialPredicate::Projection(_) = predicate.skip_binder() {
None
} else {
Some(predicate.with_self_ty(tcx, tcx.types.trait_object_dummy_self))
}
});

required_region_bounds(tcx, tcx.types.trait_object_dummy_self, predicates)
}

/// Given a set of predicates that apply to an object type, returns
/// the region bounds that the (erased) `Self` type must
/// outlive. Precisely *because* the `Self` type is erased, the
/// parameter `erased_self_ty` must be supplied to indicate what type
/// has been used to represent `Self` in the predicates
/// themselves. This should really be a unique type; `FreshTy(0)` is a
/// popular choice.
/// `'static` would appear in the list.
///
/// N.B., in some cases, particularly around higher-ranked bounds,
/// this function returns a kind of conservative approximation.
Expand All @@ -996,13 +973,14 @@ pub fn object_region_bounds<'tcx>(
///
/// Requires that trait definitions have been processed so that we can
/// elaborate predicates and walk supertraits.
#[instrument(skip(tcx, predicates), level = "debug", ret)]
pub(crate) fn required_region_bounds<'tcx>(
pub fn object_region_bounds<'tcx>(
tcx: TyCtxt<'tcx>,
erased_self_ty: Ty<'tcx>,
predicates: impl Iterator<Item = ty::Clause<'tcx>>,
existential_predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
) -> Vec<ty::Region<'tcx>> {
assert!(!erased_self_ty.has_escaping_bound_vars());
let erased_self_ty = tcx.types.trait_object_dummy_self;

let predicates =
existential_predicates.iter().map(|predicate| predicate.with_self_ty(tcx, erased_self_ty));

traits::elaborate(tcx, predicates)
.filter_map(|pred| {
Expand Down
11 changes: 2 additions & 9 deletions compiler/rustc_type_ir/src/elaborate.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -45,14 +45,12 @@ pub trait Elaboratable<I: Interner> {

pub struct ClauseWithSupertraitSpan<I: Interner> {
pub pred: I::Predicate,
// Span of the original elaborated predicate.
pub original_span: I::Span,
// Span of the supertrait predicatae that lead to this clause.
pub supertrait_span: I::Span,
}
impl<I: Interner> ClauseWithSupertraitSpan<I> {
pub fn new(pred: I::Predicate, span: I::Span) -> Self {
ClauseWithSupertraitSpan { pred, original_span: span, supertrait_span: span }
ClauseWithSupertraitSpan { pred, supertrait_span: span }
}
}
impl<I: Interner> Elaboratable<I> for ClauseWithSupertraitSpan<I> {
Expand All @@ -63,7 +61,6 @@ impl<I: Interner> Elaboratable<I> for ClauseWithSupertraitSpan<I> {
fn child(&self, clause: <I as Interner>::Clause) -> Self {
ClauseWithSupertraitSpan {
pred: clause.as_predicate(),
original_span: self.original_span,
supertrait_span: self.supertrait_span,
}
}
Expand All @@ -75,11 +72,7 @@ impl<I: Interner> Elaboratable<I> for ClauseWithSupertraitSpan<I> {
_parent_trait_pred: crate::Binder<I, crate::TraitPredicate<I>>,
_index: usize,
) -> Self {
ClauseWithSupertraitSpan {
pred: clause.as_predicate(),
original_span: self.original_span,
supertrait_span: supertrait_span,
}
ClauseWithSupertraitSpan { pred: clause.as_predicate(), supertrait_span: supertrait_span }
}
}

Expand Down

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