bjoernager/rust
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Auto merge of #127388 - compiler-errors:elaboration-tweaks, r=lcnr

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Elaboration tweaks

Removes `Filter::OnlySelfThatDefines` and reimplements `transitive_bounds_that_define_assoc_item` as a separate function, since I don't want to have to uplift that mode since it's both an implementation detail (only exists to avoid cycles in astconv) and requires exposing `Ident` as an associated type on `Interner`.

r? lcnr
This commit is contained in:
bors 2024-07-06 15:56:16 +00:00
commit 8a8ad3433e
1 changed files with 29 additions and 18 deletions
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47
compiler/rustc_infer/src/traits/util.rs
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@ -3,6 +3,7 @@ use smallvec::smallvec;
use crate::infer::outlives::components::{push_outlives_components, Component};
use crate::traits::{self, Obligation, ObligationCauseCode, PredicateObligation};
use rustc_data_structures::fx::FxHashSet;
use rustc_middle::ty::ToPolyTraitRef;
use rustc_middle::ty::{self, Ty, TyCtxt, Upcast};
use rustc_span::symbol::Ident;
use rustc_span::Span;
@ -82,7 +83,6 @@ pub struct Elaborator<'tcx, O> {
enum Filter {
All,
OnlySelf,
OnlySelfThatDefines(Ident),
}
/// Describes how to elaborate an obligation into a sub-obligation.
@ -252,12 +252,6 @@ impl<'tcx, O: Elaboratable<'tcx>> Elaborator<'tcx, O> {
self
}
/// Filter to only the supertraits of trait predicates that define the assoc_ty.
pub fn filter_only_self_that_defines(mut self, assoc_ty: Ident) -> Self {
self.mode = Filter::OnlySelfThatDefines(assoc_ty);
self
}
fn elaborate(&mut self, elaboratable: &O) {
let tcx = self.visited.tcx;
@ -277,9 +271,6 @@ impl<'tcx, O: Elaboratable<'tcx>> Elaborator<'tcx, O> {
let predicates = match self.mode {
Filter::All => tcx.explicit_implied_predicates_of(data.def_id()),
Filter::OnlySelf => tcx.explicit_super_predicates_of(data.def_id()),
Filter::OnlySelfThatDefines(ident) => {
tcx.explicit_supertraits_containing_assoc_item((data.def_id(), ident))
}
};
let obligations =
@ -405,14 +396,14 @@ impl<'tcx, O: Elaboratable<'tcx>> Iterator for Elaborator<'tcx, O> {
pub fn supertraits<'tcx>(
tcx: TyCtxt<'tcx>,
trait_ref: ty::PolyTraitRef<'tcx>,
) -> FilterToTraits<Elaborator<'tcx, ty::Predicate<'tcx>>> {
) -> FilterToTraits<Elaborator<'tcx, ty::Clause<'tcx>>> {
elaborate(tcx, [trait_ref.upcast(tcx)]).filter_only_self().filter_to_traits()
}
pub fn transitive_bounds<'tcx>(
tcx: TyCtxt<'tcx>,
trait_refs: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
) -> FilterToTraits<Elaborator<'tcx, ty::Predicate<'tcx>>> {
) -> FilterToTraits<Elaborator<'tcx, ty::Clause<'tcx>>> {
elaborate(tcx, trait_refs.map(|trait_ref| trait_ref.upcast(tcx)))
.filter_only_self()
.filter_to_traits()
@ -427,17 +418,37 @@ pub fn transitive_bounds_that_define_assoc_item<'tcx>(
tcx: TyCtxt<'tcx>,
trait_refs: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
assoc_name: Ident,
) -> FilterToTraits<Elaborator<'tcx, ty::Predicate<'tcx>>> {
elaborate(tcx, trait_refs.map(|trait_ref| trait_ref.upcast(tcx)))
.filter_only_self_that_defines(assoc_name)
.filter_to_traits()
) -> impl Iterator<Item = ty::PolyTraitRef<'tcx>> {
let mut seen = FxHashSet::default();
let mut stack: Vec<_> = trait_refs.collect();
std::iter::from_fn(move || {
while let Some(trait_ref) = stack.pop() {
if !seen.insert(tcx.anonymize_bound_vars(trait_ref)) {
continue;
}
stack.extend(
tcx.explicit_supertraits_containing_assoc_item((trait_ref.def_id(), assoc_name))
.instantiate_own_identity()
.map(|(clause, _)| clause.instantiate_supertrait(tcx, trait_ref))
.filter_map(|clause| clause.as_trait_clause())
// FIXME: Negative supertraits are elaborated here lol
.map(|trait_pred| trait_pred.to_poly_trait_ref()),
);
return Some(trait_ref);
}
None
})
}
///////////////////////////////////////////////////////////////////////////
// Other
///////////////////////////////////////////////////////////////////////////
impl<'tcx> Elaborator<'tcx, ty::Predicate<'tcx>> {
impl<'tcx> Elaborator<'tcx, ty::Clause<'tcx>> {
fn filter_to_traits(self) -> FilterToTraits<Self> {
FilterToTraits { base_iterator: self }
}
@ -449,7 +460,7 @@ pub struct FilterToTraits<I> {
base_iterator: I,
}
impl<'tcx, I: Iterator<Item = ty::Predicate<'tcx>>> Iterator for FilterToTraits<I> {
impl<'tcx, I: Iterator<Item = ty::Clause<'tcx>>> Iterator for FilterToTraits<I> {
type Item = ty::PolyTraitRef<'tcx>;
fn next(&mut self) -> Option<ty::PolyTraitRef<'tcx>> {