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Auto merge of #128746 - compiler-errors:cache-super-outlives, r=lcnr

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Cache supertrait outlives of impl header for soundness check

This caches the results of computing the transitive supertraits of an impl and filtering it to its outlives obligations. This is purely an optimization to improve https://github.com/rust-lang/rust/pull/124336.
This commit is contained in:
bors 2024-08-10 10:22:06 +00:00
commit 48090b11b5
4 changed files with 42 additions and 26 deletions
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42
compiler/rustc_trait_selection/src/traits/select/mod.rs
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@ -17,7 +17,6 @@ use rustc_hir::LangItem;
use rustc_infer::infer::relate::TypeRelation;
use rustc_infer::infer::BoundRegionConversionTime::{self, HigherRankedType};
use rustc_infer::infer::DefineOpaqueTypes;
use rustc_infer::traits::util::elaborate;
use rustc_infer::traits::TraitObligation;
use rustc_middle::bug;
use rustc_middle::dep_graph::{dep_kinds, DepNodeIndex};
@ -2801,31 +2800,22 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
}
// Register any outlives obligations from the trait here, cc #124336.
if matches!(self.tcx().def_kind(def_id), DefKind::Impl { of_trait: true })
&& let Some(header) = self.tcx().impl_trait_header(def_id)
{
let trait_clause: ty::Clause<'tcx> =
header.trait_ref.instantiate(self.tcx(), args).upcast(self.tcx());
for clause in elaborate(self.tcx(), [trait_clause]) {
if matches!(
clause.kind().skip_binder(),
ty::ClauseKind::TypeOutlives(..) | ty::ClauseKind::RegionOutlives(..)
) {
let clause = normalize_with_depth_to(
self,
param_env,
cause.clone(),
recursion_depth,
clause,
&mut obligations,
);
obligations.push(Obligation {
cause: cause.clone(),
recursion_depth,
param_env,
predicate: clause.as_predicate(),
});
}
if matches!(tcx.def_kind(def_id), DefKind::Impl { of_trait: true }) {
for clause in tcx.impl_super_outlives(def_id).iter_instantiated(tcx, args) {
let clause = normalize_with_depth_to(
self,
param_env,
cause.clone(),
recursion_depth,
clause,
&mut obligations,
);
obligations.push(Obligation {
cause: cause.clone(),
recursion_depth,
param_env,
predicate: clause.as_predicate(),
});
}
}